Vocab v22

craniotomy

cutting into the skull

asymptomatic

(of a condition or a person) producing or showing no symptoms.

for all intents and purposes

—used to say that one thing has the same effect or result as something else. Their decision to begin bombing was, for all intents and purposes, a declaration of war.

polycrystals

-Most engineering materials are polycrystals -properties may/may not vary with direction -if grains are randomly oriented: isotropic -if grains are textured: anisotropic Polycrystalline or multicrystalline materials, or polycrystals are solids that are composed of many crystallites of varying size and orientation. Most inorganic solids are polycrystalline, including all common metals, many ceramics, rocks, and ice.

"You are not entitled to your opinion. You are entitled to your informed opinion. No one is entitled to be ignorant."

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No technology does more to confirm the notion that man has tamed nature than the ability to split the atom.

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Real scientists are thinkers and philosophers who use the rules of science to try and falsify their own conclusions. Most academics don't work that way and can therefore be dismissed as teachers of known facts (which is admirable but doesn't make them scientists).

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How many moons are in our solar system?

214

how fast does the sun rotate mph

4,467 mph

Taser vs Stun gun

A "stun gun" is typically a hand-held device that only produces an electrical arc between the contacts at the end of the device. Pressing those contacts against a person will create the disruption of the neuromuscular system. The stun gun only affects a small area, although the pain can be very intense. A Taser is the brand name of a certain device which fires probes, connected by wire, from the device into a person up to about 25 feet away. If both probes connect, the neuromuscular disruption will affect any major muscle groups between the probes, such as core muscles and leg muscles if the probes contact the back and a thigh. The Taser is quite a different device. The Taser pulse is at the same frequency that your own nervous system uses to activate the voluntary muscles. So... When you get a solid "hit" with the Taser probes, the pulse produce severe, uncontrollable muscular contraction... Often through the whole body.

Radioisotope piezoelectric generator

A Radioisotope piezoelectric generator converts energy stored in the radioactive material directly into motion to generate electricity by the repeated deformation of a piezoelectric material. This approach creates a high-impedance source and, unlike chemical batteries, the devices will work in a very wide range of temperatures. A piezoelectric cantilever is mounted directly above a base of the radioactive isotope nickel-63. All of the radiation emitted as the millicurie-level nickel-63 thin film decays is in the form of beta radiation, which consists of electrons. As the cantilever accumulates the emitted electrons, it builds up a negative charge at the same time that the isotope film becomes positively charged. The beta particles essentially transfer electronic charge from the thin film to the cantilever. The opposite charges cause the cantilever to bend toward the isotope film. Just as the cantilever touches the thin-film isotope, the charge jumps the gap. That permits current to flow back onto the isotope, equalizing the charge and resetting the cantilever. As long as the isotope is decaying - a process that can last for decades - the tiny cantilever will continue its up-and-down motion. As the cantilever directly generates electricity when deformed, a charge pulse is released each time the cantilever cycles. Radioactive isotopes can continue to release energy over periods ranging from weeks to decades. The half-life of nickel-63, for example, is over 100 years. Thus, a battery using this isotope might continue to supply useful energy for at least half that time. Researchers have demonstrated devices with about 7% efficiency with high frequencies of 120 Hz to low-frequency (every three hours) self-reciprocating actuators.

St. Elmo's fire

A buildup of electrical charge on the airplane St. Elmo's fire is a weather phenomenon in which luminous plasma is created by a corona discharge from a sharp or pointed object in a strong electric field in the atmosphere. St. Elmo's fire is named after St. Erasmus of Formia, the patron saint of sailors When flying at high latitudes such as this, even at 34,000 feet we were well above the Troposphere and flying in the Stratosphere where the air tends to be very dry compared to in the Troposphere. The outside temperature was about -62 Celsius as I recall only because this is about 10 degrees colder than standard for this altitude and is a indicator of Stratospheric flight (anything less than -56C). As a result large build ups of static electricity can happen even though the aircraft has static wicks on the wings and tail surfaces to "wick off" static electricity.

cyclotron

A device used to accelerate charged particles to high energies for bombarding the nuclei of atoms. A positively charged particle can be made to accelerate to large energies/velocities by making it pass through a moderate value of electric field, a number of times. This can be done with the help of a strong perpendicular magnetic field. 1. A cyclotron cannot be used to accelerate electrons because electrons are of very small mass. Thus, the velocity will be increased to such a great extent that the electron will be thrown out of the step with the oscillating field. 2. A cyclotron cannot be used to accelerate neutral particles.

Genetically Engineered Tobacco Does Photosynthesis More Efficiently

A hack to the photosynthesis of tobacco increased its growth by 40 percent, researchers reported today in Science. The team now hopes to make similar changes to soybeans, potatoes, and other food crops.

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness. Melatonin is a hormone that regulates the sleep-wake cycle. It is primarily released by the pineal gland. As a supplement, it is often used for the short-term treatment of trouble sleeping such as from jet lag or shift work. Evidence of benefit, however, is unclear.

geological hotspot

A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth, called the crust, where magma is hotter than surrounding magma. The magma plume causes melting and thinning of the rocky crust and widespread volcanic activity.

Magnetic domain

A magnetic domain is a region within a magnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction.

vanity metric

A metric that is not actionable, and exists to make us feel better or show off. Vanity metrics are measurements and calculations that are designed to be impressive as opposed to actionable or relevant to core business goals such as revenue and operating margins. They tend to include things like page views of a website that produce big numbers that don't necessarily result in revenue. Being book-smart just for the sake of being book-smart is a vanity metric for your ego.

selenophile

A person who loves the moon

Photometer

A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, photodiode, or photomultiplier.

Photoresistor

A photoresistor (or light-dependent resistor, LDR, or photo-conductive cell) is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light-activated and dark-activated switching circuits. The main component for the construction of LDR is cadmium sulphide (CdS), which is used as the photoconductor and contains no or very few electrons when not illuminated. In the absence of light it is designed to have a high resistance inthe range of megaohms. As soon as light falls on the sensor, the electrons are liberated and the conductivity of the material increases. When the light intensity exceeds a certain frequency, the photons absorbed by the semiconductor give band electrons the energy required to jump into the conduction band. This causes the free electrons or holes to conduct electricity and thus dropping the resistance dramatically (< 1 Kiloohm).

transform boundary

A plate boundary where two plates move past each other in opposite directions A transform fault or transform boundary is a plate boundary where the motion is predominantly horizontal. It ends abruptly and is connected to another transform, a spreading ridge, or a subduction zone

Balmer series

A set of spectral lines that appear in the visible light region when a hydrogen atom undergoes a transition from energy levels n>2 to n=2. The Balmer series, or Balmer lines in atomic physics, is one of a set of six named series describing the spectral line emissions of the hydrogen atom. The Balmer series is calculated using the Balmer formula, an empirical equation discovered by Johann Balmer in 1885. The Balmer series is the portion of the emission spectrum of hydrogen that represents electron transitions from energy levels n > 2 to n = 2. These are four lines in the visible spectrum. They are also known as the Balmer lines. The four visible Balmer lines of hydrogen appear at 410 nm, 434 nm, 486 nm and 656 nm

Spectral line

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.

what causes super moon

A supermoon happens when the full moon coincides with the moon's closest approach to Earth in its orbit. Supermoons make the moon appear a little brighter and closer than normal, although the difference is hard to spot with the naked eye.

Thermoplastic

A thermoplastic, or thermosoftening plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

How many US dollars is 100 trillion Zimbabwe dollars?

A trillion, by the way, is a million million. There are 12 zeros in a trillion. Add another two to reach the total on the Zimbabwean 100 trillion dollar bill, the note with the most zeroes of any legal tender in all recorded history.May 14, 2016

Excimer

A type of lasing energy that is created when electrons are removed from the lasing medium. An excimer (originally short for excited dimer) is a short-lived dimeric or heterodimeric molecule formed from two species, at least one of which has completely filled valence shell by electrons (for example, noble gases). In this case, formation of molecules is possible only if such atom is in an electronic excited state. Heteronuclear molecules and molecules that have more than two species are also called exciplex molecules (originally short for excited complex). Excimers are often diatomic and are composed of two atoms or molecules that would not bond if both were in the ground state. The lifetime of an excimer is very short, on the order of nanoseconds. Binding of a larger number of excited atoms forms Rydberg matter clusters, the lifetime of which can exceed many seconds.

What are AGM batteries?

AGM (Absorbent glass mat) batteries differ from flooded lead acid types in that the electrolyte is held in mats, as opposed to freely flooding the plates. Glass fibers are woven into a mat to increase surface area enough to hold sufficient electrolyte on the cells for their lifetime.

Abell 1689

Abell 1689 is one of the biggest and most massive galaxy clusters known and acts as a gravitational lens, distorting the images of galaxies that lie behind it. It has the largest system of gravitational arcs ever found. Abell 1689 shows over 160,000 globular clusters, the largest population ever found.

Abell 2218

Abell 2218 is a cluster of galaxies about 2 billion light-years away in the constellation Draco. Acting as a powerful lens, it magnifies and distorts all galaxies lying behind the cluster core into long arcs. The lensed galaxies are all stretched along the cluster's center and some of them are multiply imaged. Number of galaxies: ~10,000

Underground lake

An underground lake or subterranean lake is a lake under the surface of the Earth. Such lakes may be associated with caves, aquifers, or springs. They are typically very low in salinity.

Anhedral wing

Anhedral angle, the downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft.

Loa loa

African eye worm Loa loa is the filarial nematode species that causes Loa loa filariasis. Loa loa actually means "worm worm", but is commonly known as the "eye worm", as it localizes to the conjunctiva of the eye. Loa loa is commonly found in Africa. It mainly inhabits rain forests in West Africa and has native origins in Ethiopia. Loiasis, called African eye worm by most people, is caused by the parasitic worm Loa loa. It is passed on to humans through the repeated bites of deer flies (also known as mango flies or mangrove flies) of the genus Chrysops. The flies that pass on the parasite breed in certain rain forests of West and Central Africa. Infection with the parasite can also cause repeated episodes of itchy swellings of the body known as Calabar swellings. Knowing whether someone has a Loa loa infection has become more important in Africa because the presence of people with Loa loa infection has limited programs to control or eliminate onchocerciasis (river blindness) and lymphatic filariasis (elephantiasis). There may be more than 29 million people who are at risk of getting loiasis in affected areas of Central and West Africa.

Market fundamentalism

An absolute faith in the market, reflected in the belief that the market mechanism offers solutions to all economic and social problems markets will take care of all our needs

Ammeter shunt

An ammeter shunt is a very low-resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current. Shunt voltage drop is used in conjunction with an ammeter to measure amperage of a circuit.

Atomic battery

An atomic battery, nuclear battery, tritium battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction. Compared to other batteries, they are very costly, but have an extremely long life and high energy density, and so they are mainly used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems and automated scientific stations in remote parts of the world. Batteries using the energy of radioisotope decay to provide long-lived power (10-20 years) are being developed internationally. Conversion techniques can be grouped into two types: thermal and non-thermal. The thermal converters (whose output power is a function of a temperature differential) include thermoelectric and thermionic generators. The non-thermal converters (whose output power is not a function of a temperature difference) extract a fraction of the incident energy as it is being degraded into heat rather than using thermal energy to run electrons in a cycle. Atomic batteries usually have an efficiency of 0.1-5%. High-efficiency betavoltaics have 6-8%.[4]

highest pressure reached in lab environment

An international team of scientists has created the highest static pressure ever achieved in a lab: Using a special high pressure device, the researchers investigated the behavior of the metal osmium at pressures of up to 770 Gigapascals -- more than twice the pressure in the inner core of the Earth 1 gigapascal = 145038 psi

Optoelectric nuclear battery

An opto-electric nuclear battery is a device that converts nuclear energy into light, which it then uses to generate electrical energy. A beta-emitter such as technetium-99 or strontium-90 is suspended in a gas or liquid containing luminescent gas molecules of the excimer type, constituting a "dust plasma." This permits a nearly lossless emission of beta electrons from the emitting dust particles. The electrons then excite the gases whose excimer line is selected for the conversion of the radioactivity into a surrounding photovoltaic layer such that a lightweight, low-pressure, high-efficiency battery can be realised. These nuclides are relatively low-cost radioactive waste from nuclear power reactors. The diameter of the dust particles is so small (a few micrometers) that the electrons from the beta decay leave the dust particles nearly without loss. The surrounding weakly ionized plasma consists of gases or gas mixtures (such as krypton, argon, and xenon) with excimer lines such that a considerable amount of the energy of the beta electrons is converted into this light. The surrounding walls contain photovoltaic layers with wide forbidden zones as e.g. diamond which convert the optical energy generated from the radiation into electrical energy. The battery would consist of an excimer of argon, xenon, or krypton (or a mixture of two or three of them) in a pressure vessel with an internal mirrored surface, finely-ground radioisotope, and an intermittent ultrasonic stirrer, illuminating a photocell with a bandgap tuned for the excimer.[1] When the beta active nuclides (e.g., krypton-85 or argon-39) emit beta particles, they excite their own electrons in the narrow excimer band at a minimum of thermal losses that this radiation is converted in a high band gap photovoltaic layer (e.g. in p-n diamond) very efficiently into electricity. The electric power per weight compared with existing radionuclide batteries can then be increased by a factor 10 to 50 and more. If the pressure-vessel is carbon fiber/epoxy the weight-to-power ratio is said to be comparable to an air-breathing engine with fuel tanks. The advantage of this design is that precision electrode assemblies are not needed, and most beta particles escape the finely-divided bulk material to contribute to the battery's net power.[2]

how to extract argon from air

Argon is isolated from air by fractionation, most commonly by cryogenic fractional distillation, a process that also produces purified nitrogen, oxygen, neon, krypton and xenon. Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fractionate. Generally the component parts have boiling points that differ by less than 25 °C (45 °F) from each other under a pressure of one atmosphere. If the difference in boiling points is greater than 25 °C, a simple distillation is typically used. Contents

Does every atom have half-life?

As far as we know, the atoms that constitute most elements are completely stable. If left to themselves they will never change. For a few elements, the atoms may spontaneously emit a particle from the nucleus and become a different element. This process is known as radioactive decay. If that new element is not stable the same thing will happen, but eventually the decay will result in a stable atom and the process will stop. The concept of half life only applies to radioactive elements so most elements do not have a half life. But technically they do, since proton decay will occur in 10^30 years...

How does an MRI work?

Atomic number is the number of protons in an atom. Mass number is the number of protons + the number of neutrons in an atom. Particles have an intrinsic property called spin. Given the right conditions, nuclei also have a net spin. You can use the following rules to find out yourself: If the number of protons is even and the number of neutrons is also even, then the nucleus has no spin. If the mass number is odd, then the nucleus has half-integer spin i.e 1/2, 3/2, 5/2 etc. If the number of protons is odd and the number of neutrons is also odd, then the nucleus has integer spin i.e 1, 2, 3 etc. It is a necessary condition for a nucleus to have spin, to be able to do NMR (which is the phenomenon that MRI is based on). Hydrogen atom has only 1 proton in the nucleus, so it's odd and therefore hydrogen nucleus has spin. A proton is also a fermion so it has a spin 1/2. In the absence of an external magnetic field, the total magnetization of a sample (tissue, muscles, organs and so on) is zero. This is because the total magnetization is the sum of all the individual magnetic moments and if not in the presence of a strong static magnetic field, these magnetic moments are randomly oriented and everything is cancelled out. Now, if we turn a magnetic field on, the magnetization of the sample "aligns" with the direction of the magnetic field and since the proton has spin 1/2, then by the usual quantum mechanical laws, the energy levels split into two states. One being slightly more overpopulated than the other. This means that the magnetization is now non-zero, since there is an asymmetry in the population of the states. The magnetic moments interact with the magnetic field through the Zeeman interaction and then the magnetic field exerts a mechanical torque on the nucleus making it precess in the direction of the magnetic field lines. When we send a radio-pulse to our sample, we excite and (eventually) saturate it. Then we wait a bit (a specific bit nonetheless) and repeat the same sequence of events, with a few parameters slightly changed from the previous ones. All of this information is stored in the computer, where it's being Fourier transformed and analog to digital converted which can then be formed into an image. Of course this would be the case if the patient was sitting still at all times, if the static magnetic field was completely homogeneous and if there were no other sources to distort the information obtained, which would in turn compromise the final image produced. There are some methods which account for these things and a few mechanical components of the MRI system that get turned on and off accordingly to account for inhomogeneities and so on. But in any case, this is the main process.

ayrton shunt

Ayrton shunt or universal shunt is a high-resistance shunt used in galvanometers to increase their range without changing the damping. The circuit is named after its inventor William E. Ayrton. Multi Range ammeters that use this technique are more accurate than those using a make-before-break switch.

Azurite

Azurite is a soft stone, named for its deep "azure blue" color. It is a copper carbonate mineral found in the upper oxidized portions of copper ore formed in masses, nodules, tabular or prismatic crystals, sometimes with a vitreous luster.

Why isn't honey safe for kids under two?

Because honey might contain clostridium spores. These spores can't be killed by normal heat treatment, and can cause infections in small infants (and generally aren't for older children). Now, of course, not all honey contains those spores, kids might eat honey and be fine. But the danger of it outweighs the benefits, so it's generally advised against. Interesting side note: apparently honey can be treated with gamma radiation, which sterilizes it of spores and leaves the honey safe to eat. But that's a pretty expensive treatment when the only benefit is giving your baby honey slightly sooner than you'd be able to otherwise.

How does LED work?

Before going into how LED works, let's first take a brief look at light self. Since ancient times man has obtained light from various sources like sun rays, candles and lamps. In 1879, Thomas Edison invented the incandescent light bulb. In the light bulb, an electric current is passed through a filament inside the bulb. When sufficient current is passed through the filament, it gets heated up and emits light. The light emitted by the filament is the result of electrical energy converted into heat energy which in turn changes into light energy. Unlike the light bulb in which electrical energy first converts into heat energy, the electrical energy can also be directly converted into light energy. In Light Emitting Diodes (LEDs), electrical energy flowing through it is directly converted into light energy. A light Emitting Diode (LED) is an optical semiconductor device that emits light when voltage is applied. In other words, LED is an optical semiconductor device that converts electrical energy into light energy. When Light Emitting Diode (LED) is forward biased, free electrons in the conduction band recombines with the holes in the valence band and releases energy in the form of light. The process of emitting light in response to the strong electric field or flow of electric current is called electroluminescence. A normal p-n junction diode allows electric current only in one direction. It allows electric current when forward biased and does not allow electric current when reverse biased. Thus, normal p-n junction diode operates only in forward bias condition. Like the normal p-n junction diodes, LEDs also operates only in forward bias condition. To create an LED, the n-type material should be connected to the negative terminal of the battery and p-type material should be connected to the positive terminal of the battery. In other words, the n-type material should be negatively charged and the p-type material should be positively charged. The construction of LED is similar to the normal p-n junction diode except that gallium, phosphorus and arsenic materials are used for construction instead of silicon or germanium materials. In normal p-n junction diodes, silicon is most widely used because it is less sensitive to the temperature. Also, it allows electric current efficiently without any damage. In some cases, germanium is used for constructing diodes. However, silicon or germanium diodes do not emit energy in the form of light. Instead, they emit energy in the form of heat. Thus, silicon or germanium is not used for constructing LEDs. A Light Emitting Diode (LED) consists of three layers: p-type semiconductor, n-type semiconductor and depletion layer. The p-type semiconductor and the n-type semiconductor are separated by a depletion region or depletion layer. P-type semiconductor When trivalent impurities are added to the intrinsic or pure semiconductor, a p-type semiconductor is formed. In p-type semiconductor, holes are the majority charge carriers and free electrons are the minority charge carriers. Thus, holes carry most of the electric current in p-type semiconductor. N-type semiconductor When pentavalent impurities are added to the intrinsic semiconductor, an n-type semiconductor is formed. In n-type semiconductor, free electrons are the majority charge carriers and holes are the minority charge carriers. Thus, free electrons carry most of the electric current in n-type semiconductor. Depletion layer or region Depletion region is a region present between the p-type and n-type semiconductor where no mobile charge carriers (free electrons and holes) are present. This region acts as barrier to the electric current. It opposes flow of electrons from n-type semiconductor and flow of holes from p-type semiconductor. To overcome the barrier of depletion layer, we need to apply voltage which is greater than the barrier potential of depletion layer. If the applied voltage is greater than the barrier potential of the depletion layer, the electric current starts flowing.

Betavoltaic device

Betavoltaic devices, also known as betavoltaic cells, are generators of electric current, in effect a form of battery, which use energy from a radioactive source emitting beta particles (electrons). A common source used is the hydrogen isotope tritium. Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then is used to generate electricity (thermoelectric and thermionic sources), betavoltaics use a non-thermal conversion process; converting the electron-hole pairs produced by the ionization trail of beta particles traversing a semiconductor.[1] The primary use for betavoltaics is for remote and long-term use, such as spacecraft requiring electrical power for a decade or two. Recent progress has prompted some to suggest using betavoltaics to trickle-charge conventional batteries in consumer devices, such as cell phones and laptop computers.[7] As early as 1973, betavoltaics were suggested for use in long-term medical devices such as pacemakers.[4] Although betavoltaics use a radioactive material as a power source, the beta particles used are low energy and easily stopped by a few millimetres of shielding. With proper device construction (that is, proper shielding and containment), a betavoltaic device would not emit dangerous radiation. Leakage of the enclosed material would engender health risks, just as leakage of the materials in other types of batteries (such as lithium, cadmium and lead) leads to significant health and environmental concerns.[8] As radioactive material emits, it slowly decreases in activity (refer to half-life). Thus, over time a betavoltaic device will provide less power. For practical devices, this decrease occurs over a period of many years. For tritium devices, the half-life is 12.32 years. In device design, one must account for what battery characteristics are required at end-of-life, and ensure that the beginning-of-life properties take into account the desired usable lifetime.

bipedal

Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped, meaning "two feet". Types of bipedal movement include walking, running, or hopping. using only two legs for walking.

Weather buoy

Can measure: - Currents - Water chemistry - Environmental factors - Pollution - Anemometer to measure wind speed - Weather vane to measure wind direction - Temperature of the air - Temperature of the air and water - Barometric pressure - Humidity - Wave action

Carbon-14 decay

Carbon-14 goes through radioactive beta decay: By emitting an electron and an electron antineutrino, one of the neutrons in the carbon-14 atom decays to a proton and the carbon-14 (half-life of 5,700 ± 40 years[6]) decays into the stable (non-radioactive) isotope nitrogen-14.

Blood Brain Barrier (BBB)

Cellular structure prevents bacteria and large molecules from entering brain. Water, Oxygen, CO2, Glucose, Alcohol and sometimes viruses get through. Well, scientifically, the BBB is something that separates the extracellular fluid of the brain from the blood circulating in the capillaries of the Central Nervous System. This separation is achieved by endothelial cells and their tight junctions which prevent particles that are larger than a specific threshold size from entering into the brain extracellular fluid. Our brain, being a complex and extremely vital organ, needs special protection against foreign particles that may be present in the circulating blood. Before we start to marvel at the beauty with which nature tries to protect our vital organs, it is worth mentioning that it comes with a price. The very barrier that prevents foreign particles from reaching the brain also stops therapeutic drugs from crossing over to treat brain disorders. Most therapeutic drugs are larger than the permissible size threshold of the BBB, and it becomes difficult to deliver these drugs for treating Alzheimer's, Parkinson's, and such brain-related disorders. A lot of work is being done to make the BBB transiently permeable by playing around with the tight junctions and other features of the barrier in order to improve drug delivery to various sites in the brain.

Chemoautotrophic bacteria

Chemoautotrophic bacteria get their energy from oxidizing inorganic compounds. In other words, instead of using the energy of photons from the sun, they break the chemical bonds of substances that don't contain carbon in order to get their energy.

Chemotroph

Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic or inorganic. The chemotroph designation is in contrast to phototrophs, which use solar energy. Chemotrophs can be either autotrophic or heterotrophic.

piloerection

Condition of the hair standing straight up; goosebumps

cyanosis

Cyanosis refers to a bluish cast to the skin and mucous membranes. Peripheral cyanosis is when there is a bluish discoloration to your hands or feet. It's usually caused by low oxygen levels in the red blood cells or problems getting oxygenated blood to your body.

diffraction

Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. Caused by photon superposition. Quantum mechanics is back at it again

dihedral wing

Dihedral angle is the upward angle from horizontal of the wings or tailplane of a fixed-wing aircraft.

Double star

Double Star, a pair of closely-spaced stars that to the unaided eye usually appear as a single star. The pair is called an optical double if the two stars seem to be close together only because of their alignment as seen from earth. A true double star is called a binary star, or binary system.

How an electric fence works?

Electric fences are designed to create an electrical circuit when touched by a person or animal. A component called a power energizer converts power into a brief high voltage pulse. One terminal of the power energizer releases an electrical pulse along a connected bare wire about once per second. Another terminal is connected to a metal rod implanted in the earth, called a ground or earth rod. A person or animal touching both the wire and the earth during a pulse will complete an electrical circuit and will conduct the pulse, causing an electric shock. The effects of the shock depend upon the voltage, the energy of the pulse, the degree of contact between the recipient and the fence and ground and the route of the current through the body; it can range from barely noticeable to uncomfortable, painful or even lethal. A person, animal, or object completes the fence circuit to ground rods that then feed back to a main module.

how do desiccants absorb water?

Essentially microscopic low pressure pockets absorb water out of the air due to pressure always going high to low. Silica Gel, SiO2, is essentially a synthetic, microporous form of sand. It's produced in small, irregular beads that contain thousands of microscopic cavities. These cavities create a low vapor pressure inside it, which makes the beads hygroscopic - i.e. they tend to adsorb water molecules from the humid air, which has a higher vapor pressure. In a closed, humid container, pressure will be exerted on the container by the water molecules - this is vapor pressure. The air in the container has lots of water molecules, ergo it has a high vapor pressure. Because of its huge surface area due to all the microscopic pores, the dry silica will have a low vapor pressure inside it because there is no water there yet. The water molecules in the air will eventually be adsorbed (stuck) into the pores of the gel, because in closed systems, pressure will always try distribute itself equally. The gel will stop adsorbing water when equilibrium is reached, and the water vapor pressure is equal in the gel and the air. Logically, the more humid the air is, the more water will also be absorbed before equilibrium is reached. The gel is capable of holding up to roughly 40% of its own weight in water. Silica is especially useful as a desiccant because it is cheap to produce, nontoxic and nonreactive, and can keep products dry during transport that would otherwise be harmed by moisture.

fluorescence

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. the visible or invisible radiation emitted by certain substances as a result of incident radiation of a shorter wavelength such as X-rays or ultraviolet light.

fractionation

Fractionation is a separation process in which a certain quantity of a mixture (gas, solid, liquid, enzymes, suspension, or isotope) is divided during a phase transition, into a number of smaller quantities (fractions) in which the composition varies according to a gradient.

Antonov An-225 Mriya

Generally acknowledged as the largest airplane in the world, the single Antonov An-225 is the world's heaviest aircraft ever (maximum takeoff weight greater than 640 tons) and the largest heavier-than-air aircraft (in length) ever entering operational service.

is glass a liquid

Glass, however, is actually neither a liquid—supercooled or otherwise—nor a solid. It is an amorphous solid—a state somewhere between those two states of matter. And yet glass's liquid like properties are not enough to explain the thicker-bottomed windows, because glass atoms move too slowly for changes to be visible

glycolate

Glycolic acid; chemical formula C₂H₄O₃, is the smallest α-hydroxy acid. This colorless, odorless, and hygroscopic crystalline solid is highly soluble in water. It is used in various skin-care products. Glycolic acid is found in some sugar-crops. A glycolate or glycollate is a salt or ester of glycolic acid.

isotropic

Having identical values of a property in all crystallographic directions. The same in all directions Isotropy is uniformity in all orientation. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix an, hence anisotropy.

Holevo's theorem

Holevo's theorem is an important limitative theorem in quantum computing, an interdisciplinary field of physics and computer science. It is sometimes called Holevo's bound, since it establishes an upper bound to the amount of information that can be known about a quantum state (accessible information). In essence, the Holevo bound proves that given n qubits, although they can "carry" a larger amount of (classical) information (thanks to quantum superposition), the amount of classical information that can be retrieved, i.e. accessed, can be only up to n classical (non-quantum encoded) bits. This is surprising, for two reasons: (1) quantum computing is so often more powerful than classical computing, that results which show it to be only as good or inferior to conventional techniques are unusual, and (2) because it takes 2^n complex numbers to encode [actually describe] the qubits that represent a mere n bits.

human eye hertz

Human's eye can see up to 1000 FPS and, perhaps, above. - 60Hz monitor will always show 60 FPS, no matter how much FPS your game is able to provide. - High refresh rates are noticeable only in dynamic scenes; in slow or static scenes you rarely will see any difference beyond 30 FPS

Are humans made of carbon 12?

Humans (and other life forms) are made up of chemicals, of which carbon is but one element. Carbon in humans is essentially Carbon-12 (6 electrons, 6 protons and 6 neutrons). However, a very small part (parts per million) of all the carbon present in humans is Carbon-13 (6 electrons, 6 protons and 7 neutrons). An even lesser part (parts per billion or less) of all the carbon present in humans is Carbon-14 (6 electrons, 6 protons and 8 neutrons). Carbon-14 has low levels of radioactivity. You may disbelieve me. However, you must have heard of radiocarbon dating of bones, in order to estimate the age of dinosaurs, or hominid skulls. This whole thing wouldn't work if life-forms were only composed of carbon-12, which is totally NON-radioactive. You could run MRI tests with specially tuned equipment, and identify Carbon-13 present in our body (NMR magnetic probe tuned to 13C). Normal MRI equipment is tuned to proton (magnetic probe tuned to 1H). So, our bodies comprise of chemical compounds that contain Carbon-12, Carbon-13 and Carbon-14, in roughly the same proportions as it existed in the period in which we were alive.

Calabi-Yau manifold

In algebraic geometry, a Calabi-Yau manifold, also known as a Calabi-Yau space, is a particular type of manifold which has properties, such as Ricci flatness, yielding applications in theoretical physics.

alcohol

In chemistry, alcohol is any organic compound in which a hydroxyl group (-OH) is bound to a carbon atom, which in turn is bound to other hydrogen and/or carbon atoms. In general usage, alcohol refers almost always to ethanol.

Amorphous solid

In condensed matter physics and materials science, an amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In some older books, the term has been used synonymously with glass Examples of polycrystals include most metals, rocks, ceramics, and ice. A third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass, wax, and many plastics.

do leds use AC or DC

In most applications LEDs are driven by a DC power supply. LEDs consume DC current to produce light; with AC current the LED will only be lit when current flow is in the proper direction. AC applied to an LED will cause it to blink on and off, and at high frequency the LED will appear to be lit continuously.

Lyman series

In physics and chemistry, the Lyman series is a hydrogen spectral series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1, the lowest energy level of the electron. ultraviolet

Madonna-w*hore complex

In psychoanalytic literature, a Madonna-w*hore complex is the inability to maintain sexual arousal within a committed, loving relationship

Rubber duck debugging

In software engineering, rubber duck debugging is a method of debugging code. The name is a reference to a story in the book The Pragmatic Programmer in which a programmer would carry around a rubber duck and debug their code by forcing themselves to explain it, line-by-line, to the duck.

isentropic pressure

In thermodynamics, an isentropic process is an idealized thermodynamic process that is both adiabatic and reversible. The work transfers of the system are frictionless, and there is no transfer of heat or matter. Such an idealized process is useful in engineering as a model of and basis of comparison for real processes.[7]

what elements are in vitamin d

It is evident that vitamin D intake can facilitate the absorption and assimilation of essential inorganic elements (such as calcium, magnesium, copper, zinc, iron, and selenium) but also the uptake of toxic elements (such as lead, arsenic, aluminum, cobalt, and strontium)

Why clouds are dark in colour?

It is the thickness, or height of clouds, that makes them look gray/black. Clouds are made of tiny droplets of water or ice. They are formed when water vapor condenses within pockets of rising air. Under the right conditions, the air continues to be uplifted, causing the cloud to build higher and higher. The tiny water droplets and ice crystals in clouds are just the right size to scatter all colors of light, compared with the smaller molecules of air that scatter blue light most effectively. When light contains all colors, we perceive it as white. When clouds are thin, they let a large portion of the light through and appear white. But like any objects that transmit light, the thicker they are, the less light makes it through. As their thickness increases, the bottoms of clouds look darker but still scatter all colors. We perceive this as gray. If you look carefully, you will notice that the relatively flat bottoms of clouds are always a little grayer than their sides. The taller the clouds become, the grayer their bottoms look.

Relativistic mechanics

It provides a non-quantum mechanical description of a system of particles, or of a fluid, in cases where the velocities of moving objects are comparable to the speed of light c.

why do objects entering the atmosphere catch fire

It's not about altitude. It's about velocity. Objects that enter Earth's atmosphere burn not because they are falling from great height, but because they are traveling through the atmosphere at great speed The reason for the heating effect is air friction, caused due to collisions between molecules of the atmosphere and the surface of the object. These collisions transfer energy to the object and thereby heat it up. The friction depends on the speed of the object with respect to the surrounding air and the density of the air. I hope these two facts are intuitively clear. If it moves faster, it'll collide harder with molecules. If the air is denser, there will be more collisions per unit time. Both lead to more heat being generated. Now, when bodies enter the atmosphere, the primary driving force is earth's gravity, which accelerates it, and so it's speed keeps increasing till it either hits the surface or burns up. Exiting objects, however have much lower velocities. In fact, you're probably thinking about why rockets don't burn up on the way out. Entering meteors have speeds in the range of 16 to 72 kilometers per second. On the other hand, the Saturn V, the biggest baddest rocket of 'em all, clocks in at a measly 2.7 kilometers per second.

How do LCD displays work?

LCDs displays does not radiate any illumination. It only reflects or transmits illumination. Liquid crystal is an organic fluid, sealed between two glass sheets having a transparent conducting surface. When a low frequency voltage is applied, the crystal molecules rearrange their orientation to produce the display. It's a field effect device and the key to its operation is the liquid crystal or organic fluid sandwiched between two glass plates. When an ac voltage is applied across the fluid from the top metallized segments to the metallized backplane. When affected by the magnetic field of ac voltage, the fluid transmits light differently and the energized element appears as black on a silvery background. It uses a polarizing filter on the top and bottom of the display resulting in a crystal-clear display.

Lake Vostok

Lake underneath Antarctic Ice the largest of Antarctica's almost 400 known subglacial lakes. The surface of this fresh water lake is approximately 4,000 m (13,100 ft) under the surface of the ice, which places it at approximately 500 m (1,600 ft) below sea level. The lake is divided into two deep basins by a ridge. The liquid water depth over the ridge is about 200 m (700 ft), compared to roughly 400 m (1,300 ft) deep in the northern basin and 800 m (2,600 ft) deep in the southern.

why does lithium react with water

Lithium metals reacts slowly with water to form a colourless solution of lithium hydroxide (LiOH) and hydrogen gas (H2). The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic, but the reaction is slower than that of sodium (immediately below lithium in the periodic table). Lithium's single valence electron allows it to be a good conductor of electricity. It is flammable and can even explode when exposed to air and water. However, it is less reactive and explosive than the other alkali metals. Because it is so reactive, lithium is not found in its pure form in nature.

Loiasis

Loiasis, called African eye worm by most people, is caused by the parasitic worm Loa loa. It is passed on to humans through the repeated bites of deer flies (also known as mango flies or mangrove flies) of the genus Chrysops. The flies that pass on the parasite breed in certain rain forests of West and Central Africa. Infection with the parasite can also cause repeated episodes of itchy swellings of the body known as Calabar swellings. Knowing whether someone has a Loa loa infection has become more important in Africa because the presence of people with Loa loa infection has limited programs to control or eliminate onchocerciasis (river blindness) and lymphatic filariasis (elephantiasis). There may be more than 29 million people who are at risk of getting loiasis in affected areas of Central and West Africa.

mass photometry

Mass photometry is a revolutionary new way to analyze molecules. It enables the accurate mass measurement of single molecules in solution, in their native state and without the need for labels. This approach opens up new possibilities for bioanalytics and research into the functions of biomolecules.

MOOC

Massive open online course. Internet-based course containing lectures and other course materials.

occupational medicine

Medical specialty focusing on detection and prevention of diseases that arise from the work environment the branch of medicine dealing with the prevention and treatment of job-related injuries and illnesses.

How do metals react with distilled water?

Metals in distilled water corrode, which is more complicated than one would expect. Corrosion usually happens in one of four ways, listed from most to least common. The metal corrodes until an equilibrium concentration of metal ions in the water is reached. The corrosion process puts metal ions into solution and creates hydrogen gas. 2H_2O + M → H_2 + M^2^+ + 2OH^- At equilibrium, metal atoms are corroding off the metal at the same rate as ions being deposited onto the metal. Once this point is reached, a human observer would see the metal neither shrinking nor growing. For some metals (like platinum) this requires a very, very small concentration of ions in solution, so the metal will not measurably corrode. For some metals (like zinc) the equilibrium concentration is impossibly high (aka the solution becomes more metal than water), so it will keep corroding forever. For alkali metals, this process is hot enough for the hydrogen gas to ignite when it comes into contact with air. These explosions can be seen with a quick youtube search of sodium or cesium in water. If the metal is constantly flushed with new distilled water, an equilibrium concentration will never be reached, and the metal will corrode completely. This process can occur across a massive spectrum of rates depending on the conditions. There is oxygen in the water. The metal will corrode faster and to a higher equilibrium concentration than without oxygen, but otherwise this is exactly the same as case 1. O_2 + 2H_20 + 2M → 2M^2^+ + 4OH^- An oxide forms (e.g. M_2O_3 or MO_2^2^-). Sometimes the oxide is an ion. These ions also have an equilibrium concentration, so a similar process to the previous cases occurs. Other times the oxide is solid (think rust). Solids don't really have a concentration, so the metal will "rust" itself into oblivion. A passive layer forms (eg stainless steel). These special solid oxides form in thin layers coating the metal and prevent any further corrosion. The passive layer is only a few atoms thick, so it is usually invisible and really hard to measure. Passive layers are very useful because they can protect metals with high equilibrium ion concentrations from corroding. However, they only form in a very limited set of circumstances and may not be practical. Distilled water is different tap water or natural bodies of water because it lacks chlorine ions. Tap water has only very small amounts of chlorine, but it is enough to have a measurable impact on metal corrosion. Chlorine ions catalyze all the above reactions. This means they make everything happen much, much faster, but have no effect on the end result. Chlorine can also destroy the protection given by passive films.

moon bouncing signals

Moon bounce, also known as Earth-Moon-Earth (EME) communication, is a technique that sends radio wave transmissions from Earth to the Moon. The transmission is then reflected, or bounced, off the surface of the Moon and captured by an Earth-based receiver.

What Gives the Morpho Butterfly Its Magnificent Blue?

Morpho butterflies live mostly in the tropics. When resting, they fold their wings up, showing their dark earth-toned undersides. The brown, yellow and black colors are generated by pigments. But the other side is all about structural color. It gives their wings a vibrant, iridescent blue hue. Each scale is like a pixel, a tiny tile in a larger mosaic in layers of overlapping rows. ...Ridges on the scales' surface are a key component that affect how the wing spreads or refracts light, similar to a prism. When light hits these ridges, a phenomena called constructive interference comes into play. The spacing within the ridges,which look like little Christmas trees, perfectly reinforces specific wavelengths while canceling out others. This is why your eyes perceive that shimmering blue.

NGC 6751

NGC 6751, also known as the Glowing Eye Nebula or Dandelion Puffball Nebula, is a planetary nebula in the constellation Aquila. The nebula is estimated to be around 0.8 light-years in diameter. The star at the centre of the nebula has a surface temperature of approximately 140,000 K. The New General Catalogue of Nebulae and Clusters of Stars (NGC)

Dead reckoning

Navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction and speed, groundspeed, and elapsed time. In navigation, dead reckoning is the process of calculating one's current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time and course

neutron degeneracy

No two neutrons can occupy identical states, even under the pressure of a collapsing star of several solar masses Neutrons are all identical fermions, which means that only one neutron can occupy a given quantum state, and the overall wavefunction of a collection of neutrons must be totally antisymmetric. Now, if you confine non-interacting neutrons, let's say, inside a sphere, then there will be a discrete set of kinetic energies allowed for the neutrons. Generally you can put two neutrons, one spin up and one spin down into each allowed kinetic energy state, but no more than that. This means that the lowest possible total energy of the assembly of neutrons grows rapidly as you add more and more neutrons, since the final neutrons must go into higher and higher energy states. At zero temperature, all the allowed energy states will be filled up, up to some level, called the Fermi level by convention. This arrangement is called a degenerate Fermi gas. It is the state of a gas of fermions that exists at zero temperature. Associated with such a gas is a pressure, called the degeneracy pressure. If you imagine compressing the sphere, what will result is that the allowed energies will get larger and larger, which will further increase the pressure with increasing density. So neutron degeneracy pressure is that quantum mechanical pressure that arises since neutrons are fermions.

Why the Mid Atlantic Ridge is on the surface on Iceland?

Not only is the mid-ocean ridge changing the geography of Iceland, it's also responsible for the volcanic activity which created the island. As the two tectonic plates shift, fissures periodically form in the crust that allow molten rock from underground to surface as lava, creating Iceland's many volcanoes At Thingvellir National Park in iceland you can see the mid atlantic ridge on the surface

process c and process s

One possible explanation of alterations in feelings of sleepiness is the so-called circadian rhythm (process C) that (together with a homeostatic process - process S) regulates our sleep. One might think intuitively that the longer one is awake the more sleepy one feels. However, since the circadian rhythm also regulates sleep, these feelings might fluctuate according to the fluctuations in this circadian rhythm. So... as the figure above depicts, homeostatic sleep pressure increases with increased wakefulness (process S), while the circadian rhythm (process C) fluctuates with a rhythm of about 24 hours. As the distance between these two processes increases (depicted by the vertical line), sleep propensity will increase. When a person stays awake for a prolonged time, the circadian rhythm will continue to fluctuate, and thus sleep propensity (and possibly associated feelings of sleepiness) will fluctuate accordingly. The rhythmicity in feelings of fatigue has also been tested empirically and is depicted in the following figure. (fatigue isn't the same as sleepiness, although for ease of illustration I will use the term interchangeably). The fluctuation you see in the graph corresponds to the fluctuations in the circadian rhythm. I must however admit that this is quite a simplistic presentation in a controlled laboratory setting. Feelings of sleepiness can depend on other factors as well, and thus fluctuations in sleepiness might as well be attributed to other things: food that targets the orexin system protein can increase orexin activity, while glucose has an inhibitory effect psychostimulants e.g. caffeine: at this point little is known about what happens to modest levels of daytime sleepiness that are suppressed by caffeine. As Horne (2011) asks "Does sleepiness reappear as enhanced sleepiness and more profound sleep at night, or is it simply eliminated?" motivational factors (if we are in an environment conducive to sleep, with little stimulation then we might be able to sleep with what may only be minimal feelings of sleepiness, while the opposite might be the case as well)

does alpha centauri have planets

Only one planet has been confirmed for the Alpha Centauri system: Proxima Centauri b. It is slightly larger than the Earth, and orbits around Proxima Centauri in its habitable zone.

photometry

Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power.

Pillars of Creation

Pillars of Creation is a photograph taken by the Hubble Space Telescope of elephant trunks of interstellar gas and dust in the Eagle Nebula, specifically the Serpens constellation, some 6,500-7,000 light years from Earth.

Polyvinylidene fluoride

Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. PVDF is a specialty plastic used in applications requiring the highest purity, as well as resistance to solvents, acids and hydrocarbons. Compared to other fluoropolymers, like polytetrafluoroethylene (Teflon), PVDF has a low density (1.78 g/cm3). It is available as piping products, sheet, tubing, films, plate and an insulator for premium wire. It can be injected, molded or welded and is commonly used in the chemical, semiconductor, medical and defense industries, as well as in lithium-ion batteries. It is also available as a crosslinked closed-cell foam, used increasingly in aviation and aerospace applications. It can also be used in repeated contact with food products, as it is FDA-compliant and absolutely non-toxic.[3]

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen Cellular Respiration, is the process in which cells produce the energy they need to survive. In cellular respiration, cells use oxygen to break down the sugar glucose and store its energy in molecules of adenosine triphosphate (ATP). Cellular respiration is critical for the survival of most organisms because the energy in glucose cannot be used by cells until it is stored in ATP. Cells use ATP to power virtually all of their activities to grow, divide, replace worn out cell parts, and execute many other tasks. Cellular respiration provides the energy required for an amoeba to glide toward food, the Venus fly trap to capture its prey, or the ballet dancer to execute stunning leaps. Cellular respiration occurs within a cell constantly, day and night, and if it ceases, the cell and ultimately the organism dies. Adenosine triphosphate transports energy in cells.

why salting roads prevents ice

Pure water freezes at 32 degrees Fahrenheit, while a salt solution may not freeze until it reaches minus 6 degrees Fahrenheit because salt disrupts the movement of molecules entering and leaving the solid. NaCl freezes at 6 degrees, but I couldn't find what KCl freezes at, which is the salt that's actually used on roads.

Radiocarbon dating

Radiocarbon dating is a radiometric dating method that uses (14C) to determine the age of carbonaceous materials up to about 60,000 years old. The technique was developed by Willard Libby and his colleagues in 1949[9] during his tenure as a professor at the University of Chicago. Libby estimated that the radioactivity of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram of pure carbon, and this is still used as the activity of the modern radiocarbon standard. In 1960, Libby was awarded the Nobel Prize in chemistry for this work. One of the frequent uses of the technique is to date organic remains from archaeological sites. Plants fix atmospheric carbon during photosynthesis, so the level of 14C in plants and animals when they die approximately equals the level of 14C in the atmosphere at that time. However, it decreases thereafter from radioactive decay, allowing the date of death or fixation to be estimated. The initial 14C level for the calculation can either be estimated, or else directly compared with known year-by-year data from tree-ring data (dendrochronology) up to 10,000 years ago (using overlapping data from live and dead trees in a given area), or else from cave deposits (speleothems), back to about 45,000 years before the present. A calculation or (more accurately) a direct comparison of carbon-14 levels in a sample, with tree ring or cave-deposit carbon-14 levels of a known age, then gives the wood or animal sample age-since-formation. Radiocarbon is also used to detect disturbance in natural ecosystems; for example, in peatland landscapes, radiocarbon can indicate that carbon which was previously stored in organic soils is being released due to land clearance or climate change.

Radioisotope heater unit

Radioisotope heater units (RHU) are small devices that provide heat through radioactive decay. They are similar to tiny radioisotope thermoelectric generators (RTG) and normally provide about one watt of heat each, derived from the decay of a few grams of plutonium-238—although other radioactive isotopes could be used. The heat produced by these RHUs is given off continuously for several decades and, theoretically, for up to a century or more. In spacecraft, RHUs are necessary to heat critical components and subsystems. RHUs also reduce spacecraft complexity by making heater subsystems unnecessary. By having as few heating subsystems as possible, the overall complexity of the spacecraft can be reduced. While both RHUs and RTGs use the decay heat of a radioactive isotope (usually Pu-238), RHUs are generally much smaller as a result of omitting the thermocouples and heat sinks/radiators required to generate electricity from heat. Both RHUs and RTGs feature rugged, heat-resistant casings to safely contain the radioisotope in the event of a launch or re-entry vehicle failure. The total mass of a single RHU (including shielding) is about 40 grams. Similar schemes, such as thermo-ionic generators, have also been used.

When did humans start seeing blue?

Scientists generally agree that humans began to see blue as a color when they started making blue pigments. Cave paintings from 20,000 years ago lack any blue color, since as previously mentioned, blue is rarely present in nature. About 6,000 years ago, humans began to develop blue colorants

protogalactic theory

So, physicists started looking for simple mathematical symmetries that could be plugged into a quantum field theory - symmetries would then explain this apparent quark/lepton symmetry. There was one very, very attractive candidate - the SU(5) symmetry group. Plugging that fundamental mathematical symmetry into a field theory became the Glashow-Georgi theory. When you do the math (and WOW is it a lot of math...) the theory predicts twelve X bosons. Those bosons could turn a quark into a lepton. This leads to a remarkable prediction - if a heavier quark could turn into a lighter lepton, then protons could decay. This would be a new fundamental force, which could cause one of the up or down quarks inside a proton to decay into leptons. Nobody has ever observed a proton to decay, but this was not a problem for the theory, at least not at first: The X-bosons would be extremely heavy particles, thus this new force would be extremely weak, and proton decay would thus be extremely rare. How rare? Stupid rare - Initial predictions gave a proton lifetime of about 10^31 years. So, there is essentially no hope of watching one proton until it decays to confirm the theory. However, you could watch a huge collection of well over 10^31 protons and have a good chance that a few would decay. Those experiments were built, and they are still running today. Quick Summary - The X-bosons would be the carriers of a new fundamental force, like the W and Z particles are carriers of the weak force and the photon is the carrier of the electromagnetic force. This force would be part a unification of the strong force with the elecro-weak force. That unification would link particles that feel the strong force with particles that do not feel the strong force, and thus explain the apparent six quark / six lepton symmetry. Higgs Boson - The Higgs is something different. We have found the right symmetry that links the weak force with electromagnetism. (It's Su(3).) But we also need something to split that symmetry into two parts - breaking it into the weak part and the electromagnetic part that we observe. The Higgs field (and the recently discovered boson associated with it) does that job.

staphylococcus

Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae in the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms (capable of growth both aerobically and anaerobically). An infection caused by bacteria commonly found on the skin or in the nose. staph infection: staphylococcus aureus

Stony-iron meteorites

Stony-iron meteorites or siderolites are meteorites that consist of nearly equal parts of meteoric iron and silicates. This distinguishes them from the stony meteorites, that are mostly silicates, and the iron meteorites, that are mostly meteoric iron.

Calabash Nebula

The Calabash Nebula, also known as the Rotten Egg Nebula or by its technical name OH 231.84 +4.22, is a protoplanetary nebula 1.4 light years long and located some 5,000 light years from Earth in the constellation Puppis

DEKA Arm

The Deka Arm System is a battery-powered device that blends multiple approaches. Some of the Deka's functions are controlled by myoelectricity, which means the device senses movement in various muscle groups via attached electrodes, then converts those muscle movements into motor control.

E-plane and H-plane

The E-plane and H-plane are reference planes for linearly polarized waveguides, antennas and other microwave devices. In waveguide systems, as in the electric circuits, it is often desirable to be able to split the circuit power into two or more fractions. In a waveguide system, an element called a junction is used for power division. In a low frequency electrical network, it is possible to combine circuit elements in series or in parallel, thereby dividing the source power among several circuit components. In microwave circuits, a waveguide with three independent ports is called a TEE junction. The output of E-Plane Tee is 180° out of phase where the output of H-plane Tee is in phase.[1]

uranium from supernovae

The Earth's uranium has been thought to be produced in one or more supernovae over 6 billion years ago. More recent research suggests some uranium is formed in the merger of neutron stars. Uranium later became enriched in the continental crust. Radioactive decay contributes about half of the Earth's heat flux.

Huygens-Fresnel principle

The Huygens-Fresnel principle is a method of analysis applied to problems of wave propagation both in the far-field limit and in near-field diffraction and also reflection.

Lagoon Nebula

The Lagoon Nebula is a giant interstellar cloud in the constellation Sagittarius. It is classified as an emission nebula and as an H II region. The Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star-forming nebulae faintly visible to the eye from mid-northern latitudes.

NGC astronomy definition

The New General Catalogue of Nebulae and Clusters of Stars (NGC) is an extensive catalogue of astronomical deep sky objects that was compiled by John Louis Emil Dreyer in 1888. ... In total he listed 7,840 objects that are referred to as NGC objects.

Orion Nebula

The Orion Nebula, also known as M42, is a diffuse nebula situated south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae, and is visible to the naked eye in the night sky.

Rural Electrification Act

The Rural Electrification Act of 1936, enacted on May 20, 1936, provided federal loans for the installation of electrical distribution systems to serve isolated rural areas of the United States. The funding was channeled through cooperative electric power companies, most of which still exist today.

Hammer and sickle on flag

The colour red honours the red flag of the Paris Commune of 1871 and the red star and hammer and sickle are symbols of communism and socialism. The hammer symbolises urban industrial workers while the sickle symbolises agricultural workers (peasants)—who together, as the Proletarian class, form the state.

Cryosphere

The cryosphere is an all-encompassing term for those portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground. Thus, there is a wide overlap with the hydrosphere. the frozen zone

Is SSD better than HDD?

The difference between hard drives and solid state drives is in the technology used to store and retrieve data. ... HDDs (hard disc drive) are cheaper and you can get more storage space. SSDs, however, are faster, lighter, more durable, and use less energy. Your needs will dictate which storage drive will work best for you.

Hydrogen spectral series

The emission spectrum of atomic hydrogen has been divided into a number of spectral series, with wavelengths given by the Rydberg formula. These observed spectral lines are due to the electron making transitions between two energy levels in an atom. The classification of the series by the Rydberg formula was important in the development of quantum mechanics. The spectral series are important in astronomical spectroscopy for detecting the presence of hydrogen and calculating red shifts.

why clouds appear white

The light we see WITH when it is reflected from something , is so called white light. It consists of all the colors of light we are able to see, blended together. You can separate white light into the various colors with a prism. Look it up if interested. Clouds consist of tiny droplets of water that being more or less round in shape reflect light in all directions, mixing it up thoroughly. If the temperature and concentration are favorable, you see the light reflected from the cloud as white light, because most of the light hitting the cloud is white light, and under the right conditions, a cloud reflects nearly all the light that hits it. Since it was white light to begin with, and nearly all of it is still there, after bouncing around in a cloud, and off the cloud, the cloud appears to be "white" , sometimes, depending on the exact conditions in effect. If conditions are such that the cloud is dense enough to absorb a lot of light, it appears progressively darker as it absorbs more and more light rather than reflecting it.

Rubisco

The most abundant protein on earth. Performs Carbon Fixation in the Calvin Cycle. an enzyme present in plant chloroplasts, involved in fixing atmospheric carbon dioxide during photosynthesis and in oxygenation of the resulting compound during photorespiration. The researchers from US Department of Agriculture and the University of Illinois at Urbana-Champaign introduced genetic constructs that tweaked a process called photorespiration in tobacco plants. Photorespiration occurs when an enzyme called Rubisco accidentally grabs an oxygen molecule instead of the carbon dioxide that plants need for growth. This snafu, which occurs roughly 20 percent of the time, results in a plant making a toxic chemical called glycolate.

Nitrogen cycle

The nitrogen cycle is the biogeochemical cycle whereby nitrogen is converted into various chemical forms Whilst ~78% of the atmosphere is composed of nitrogen (N2), this gas is inert and unable to be used by plants and animals Chemoautrophic bacteria can convert this nitrogen gas into compounds that can be assimilated by plants and animals • Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia • Rhizobium associates with roots in a mutualistic relationship Nitrogen Fixation: The first stage of the nitrogen cycle is the conversion of inert nitrogen gas (N2) into ammonia (NH3) This reaction is catalysed by the enzyme nitrogenase, which is produced by nitrogen-fixing bacteria in the soil Azotobacter is found living freely in the soil, while Rhizobium forms a mutualistic association with the roots of legumes Rhizobium forms nodules within the plant roots and supplies ammonia to the plant in exchange for carbohydrates Ammonia (NH3) becomes ammonium (NH4+) when mixed with water, and this can be used by plants Ammonification: Ammonia can also be produced from organic sources of nitrogen (e.g. amino acids) when broken down by decomposers As a plant or animal decays, saprotrophs will decompose organic materials to produce ammonia (and ammonium ions) This process is known as ammonification and releases ammonium ions into the soil which can be absorbed by plants Nitrification: Nitrification is the conversion of ammonium ions into nitrites and nitrates by nitrifying bacteria in the soil Nitrosomonas converts ammonium ions into nitrites, while Nitrobacter can convert the nitrites into nitrates These reactions require oxygen and hence soil must be well aerated to ensure a rich supply of nitrites and nitrates Nitrites and nitrates are easier for plants to assimilate and hence function as a predominant source of nitrogen for plants • In the absence of oxygen denitrifying bacteria reduce nitrate in the soil Denitrification: Denitrification is a chemical reduction process that converts nitrates (NO3-) into nitrogen gas (N2) It is carried out by denitrifying bacteria (e.g. Pseudomonas denitrificans) in the absence of oxygen (i.e. anoxic conditions) Nitrates can be used instead of oxygen as an electron acceptor during cellular respiration, producing nitrogen gas This will only occur in oxygen-poor conditions (such as waterlogged soils) and reduces the availability of nitrates to plants

what color are mirrors

The original colors of light that are present in the room. If you shine a pure green light on a red apple, the apple will look green. When people talk about an object's "true color", they mean the color that you see when white light hits the object, since white ambient light is what we are used to in everyday life (sunlight is white). Since a good mirror reflects all colors equally, you could say that the true color of a mirror is white. In other words, if you shine white light on the mirror and everything in the room is white, you will only see white in the mirror. Note that some mirrors are not equally reflective of all colors and sometimes have a green tint.

potato clock, how it works?

The potatoes don't provide any energy. That's a common misconception, the energy actually comes from the two electrodes. The potato just acts as a salt bridge and ion supply. You see, when the two different metals are stuck into the potato, one of them releases positive ions into the liquid in the potato more easily than the other. When that happens, a negative charge builds on that electrode, causing electrons to flow through the wire to the other electrode. The ions migrate through the potato, balancing the charge at the other electrode. The electrons flowing through the wire form a current which can be used to power a small light or clock. The truth is, you could use cardboard soaked in salt water as easily as a potato (and some early batteries were made this way.) The energy comes, not from the potato, but from the chemical energy as the electrode breaks down into ions. Over time, the zinc electrode will corrode entirely and need to be replaced, but the current is usually so small that this will take a long time.

Order of magnitude

The power of 10 nearest the quantity a class in a system of classification determined by size, each class being a number of times (usually ten) greater or smaller than the one before. For example, the order of magnitude of 1500 is 3, because 1500 = 1.5 × 10³.

A chip made with carbon nanotubes, not silicon, marks a computing milestone

The prototype, described in the Aug. 29 Nature, is not yet as speedy or as small as commercial silicon devices. But carbon nanotube computer chips may ultimately give rise to a new generation of faster, more energy-efficient electronics.

Miles per gallon gasoline equivalent (MPGe)

The ratings are based on EPA's formula, in which 33.7 kilowatt-hours (121 megajoules) of electricity is equivalent to one (US) gallon of gasoline. Tesla's website was updated three weeks ago, showing 250 miles, and with the results out today from the EPA, it looks like that was enough to push Tesla to an incredible 141 MPGe combined, or only 24kWh of battery to travel 100 miles. That not only beats this year's bigger IONIQ, it beats the all-time champ, the 2017-2019.

Why does lack of oxygen turn your lips blue?

The short answer is that tissue starts looking blue due to a lack of oxygen for the same reason that veins look blue. That answer is because when oxygen is reduced, the fraction of the deoxygenated form of hemoglobin (deoxyhemoglobin) in blood increases. But this answer doesn't really go that far since contrary to what many people believe, deoxyhemoglobin by no means looks blue. In fact, it actually looks like an even darker red than the oxygenated form of hemoglobin (oxyhemoglobin). To get the real answer you need to consider how light interacts with tissue to produce the color you see. As white light hits your skin and goes into your veins/arteries, some of it will be scattered and absorbed at various points along the way. It turns out that for skin red light can penetrate more deeply than blue light. As a result, more red light can reach the blood where it will be absorbed. This absorption removes a major component of the red part of the white light spectrum, so that the light that makes it back to your eyes can look more blue. Now whether tissue will look red or blue in the presence of blood vessels will depend on a number of factors, including the depth of the vessels and the level of oxygenation. If the vessels are deeper, then the effect due to scattering described above tends to increase the likelihood that the vessels will appear blue. By contrast more superficial blood vessels (e.g. in you lips) are more likely to appear red. However, if the fraction of deoxyhemoglobin increases, then this can amplify the effect of absorbing red light. That is the reason why veins at the same depth as arteries are more likely to look blue. It's also the reason why when blood is depleted of oxygen even tissue that normally looks red (e.g. your lips) can start to acquire a bluish tint.

Speed of sound

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. At 20 °C (68 °F), the speed of sound in air is about 343 metres per second (1,235 km/h; 1,125 ft/s; 767 mph; 667 kn), or a kilometre in 2.9 s or a mile in 4.7 s. It depends strongly on temperature, but also varies by several metres per second, depending on which gases exist in the medium through which a sound wave is propagating. The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In common everyday speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: sound travels most slowly in gases; it travels faster in liquids; and faster still in solids. Sound travels at 343 m/s in air; it travels at 1,481 m/s in water (almost 4.3 times as fast as in air); and at 5,120 m/s in iron (almost 15 times as fast as in air). In an exceptionally stiff material such as diamond, sound travels at 12,000 metres per second (39,000 ft/s)[1]—about 35 times as fast as in air—which is around the maximum speed that sound will travel under normal conditions. Sound waves in solids are composed of compression waves (just as in gases and liquids), and a different type of sound wave called a shear wave, which occurs only in solids. Shear waves in solids usually travel at different speeds, as exhibited in seismology. The speed of compression waves in solids is determined by the medium's compressibility, shear modulus and density. The speed of shear waves is determined only by the solid material's shear modulus and density. In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure for the speed of an object moving through the medium. The ratio of the speed of an object to the speed of sound in the fluid is called the object's Mach number. Objects moving at speeds greater than Mach1 are said to be traveling at supersonic speeds.

Phenomenology

The study of individuals' own unique, first-person, conscious experience. how things seem to the conscious person

aquiferous system

The system of connected water channels that is unique to sponges system of openings and channels which transports water through the sponge body. Responsible for gas exchange, nutrition, excretion, reproduction system of canals for pumping water for feeding, respiration, and excretion Main function is to bring water in the sponge and gives oxygen and food particles, consisting of the osculum, spongeocoel, and ostia

Range sensor

The transmission position sensor, also known as the transmission range sensor, is an electronic sensor that provides a position input to the Powertrain Control Module (PCM) so that the transmission can be properly controlled by the PCM according to the position commanded by the sensor

Thermophotovoltaic cells

Thermophotovoltaic cells work by the same principles as a photovoltaic cell, except that they convert infrared light emitted by a hot surface rather than visible light into electricity. Thermophotovoltaic cells have an efficiency slightly higher than thermoelectric modules (TEMs) and can be overlaid on top of themselves, potentially doubling efficiency. Systems with radioisotope generators simulated by electric heaters have demonstrated efficiencies of 20%,[26] but have not yet been tested with radioisotopes. Some theoretical thermophotovoltaic cell designs have efficiencies up to 30%, but these have yet to be built or confirmed. Thermophotovoltaic cells and silicon TEMs degrade faster than metal TEMs, especially in the presence of ionizing radiation.

male argonaut octopus mating habits

They just give the female their spermatophore-loaded mating arm, and swim away to safety. Male argonaut octopuses are smaller than the females, and the male's hectocotylus simply stays intact inside the female's mantle "until the female is ready to use the sperm for fertilization", Mather says

What formed the Mid Atlantic Ridge?

This submarine Mid-Atlantic Ridge owes its formation to the movement of the continental plates on either side of the ocean. As these plates slowly separate, they leave gaps in the earth's crust. This allows molten rock from beneath the earth's crust to reach the surface, forming a new part of the ocean floor. Divergent plate boundaries

p53 protein

This tumor suppressor gene causes cell cycle arrest in G1, providing time for DNA repair. If repair is successful, cells re-enter the cycle. If unsuccessful, apoptosis p53, also known as TP53 or tumor protein is a gene that codes for a protein that regulates the cell cycle and hence functions as a tumor suppression.

uncanny valley

Used in reference to the phenomenon whereby a computer-generated figure or humanoid robot bearing a near-identical resemblance to a human being arouses a sense of unease or revulsion in the person viewing it. almost human looking, but not quite

vitamin a purpose

Vitamin A helps form and maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin. It is also known as retinol because it produces the pigments in the retina of the eye. Vitamin A promotes good eyesight, especially in low light. Foods: Beef liver. Cod liver oil. Sweet potato. Carrots. Black-eyed peas. Spinach. Broccoli. Sweet red pepper.

What is an RGB D camera?

What is RGB-D Camera (Depth Sensor) 1. Are a specific type of depth sensing devices that work in association with a RGB camera, that are able to augment the conventional image with depth information (related with the distance to the sensor) in a per-pixel basis.

ottoman empire slaves

When did slavery end in the Ottoman Empire? Even after several measures to ban slavery in the late 19th century, the practice continued largely unabated into the early 20th century. As late as 1908, female slaves were still sold in the Ottoman Empire. Sexual slavery was a central part of the Ottoman slave system throughout the history of the institution. How did the Ottoman Empire fall? Dissolution of the Ottoman Empire. The dissolution of the Ottoman Empire (1908-1922) began with the Second Constitutional Era with the Young Turk Revolution. It restored the Ottoman constitution of 1876 and brought in multi-party politics with a two stage electoral system (electoral law) under the Ottoman parliament.

Telomere

a compound structure at the end of a chromosome. A telomere is a region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos "end" and merοs "part".

how do batteries die

When the active material in the plates can no longer sustain a discharge current, a battery "dies". Normally a car (or starting) battery "ages" as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. The answer is really long, and also depends on the chemistry. After so many cycles (charge/discharge), the plates on batteries experience irregular growth, crack from water loss in the chemical reaction, or shed into the electrolyte and cannot produce the necessary power. AGM batteries experience irreversible acid stratification which lowers power. In short, the batteries die from variables that happen with repeated use. Things that speed up the "death" of a battery are extreme temperatures, larger loads on the battery, and charging errors. Roughly 80% of battery damage occurs due to improper charger use or unregulated chargers.

why do ants hate baby powder

When you deposit chalk, cornstarch or powder across their trail, the pheromone path is broken. A thin line of talcum powder at and around the places where the ants come in. It's highly desiccating, which is why it's used as "baby powder" so babies who dampen their diapers can be dry and not get diaper rash. Ants do not like it, and they will not cross a line of it.

as we get older telomeres shorten

Yet, each time a cell divides, the telomeres get shorter. When they get too short, the cell can no longer divide; it becomes inactive or "senescent" or it dies. This shortening process is associated with aging, cancer, and a higher risk of death. So telomeres also have been compared with a bomb fuse. telomeres don't shrink in space a year in space changed Scott Kelly's body, but many of those changes were only temporary and vanished after time back on the ground. https://www.theverge.com/2019/4/11/18306525/scott-mark-kelly-twins-year-international-space-station-nasa-dna-genes-health

What is the cause of carpal tunnel syndrome?

You mean median nerve entrapment? Most often it is caused by your long flexor tendons becoming inflamed and pressing on the median nerve. Think of it like sitting between two fat people on an airplane. They are the first to raise the arm rests and their adipose tissue spills over into your space. So, tendons become inflamed and press on the median nerve. Simple. Tendons most often become inflamed because we misuse them. NOT OVER USE THEM. The biggest culprit of this inflammation is when we use two muscles at the same time to move one bone. The tendon gets caught in the middle of the bone and muscle. When two forces pull simultaneously in tug of war for control of a finger bone, something has to give. Tie a string to a doorknob and pull on it. Eventually something will break. Your hand? The doorknob? The string? Now, if you pull the string just enough to create tension, the string is tensed but, not torn. But, if the door opens out and someone opens it from the other side . . . . These are called vector forces but much more complicated in our arms because every muscle is interconnected. The cure is really simple: Learn to move properly. Or, get drugs, injections and surgery.

Dimer

a compound whose molecules are composed of two identical monomers an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. The term homodimer is used when the two molecules are identical (e.g. A-A) and heterodimer when they are not (e.g. A-B). The reverse of dimerisation is often called dissociation. When two oppositely charged ions associate into dimers, they are referred to as Bjerrum pairs.

Eddy current

a current loop in a conductor caused by motional emf Current generated in a piece of metal that is moving through a changing magnetic field, producing a magnetic field that opposes the motion that caused the current Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an AC electromagnet or transformer, for example, or by relative motion between a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material. When graphed, these circular currents within a piece of metal look vaguely like eddies or whirlpools in a liquid.

globular cluster

a large compact spherical star cluster, typically of old stars in the outer regions of a galaxy. A globular cluster is a spherical collection of stars that orbits a galactic core. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin, globulus—a small sphere. A globular cluster is sometimes known, more simply, as a globular.

carbon 14

a long-lived naturally occurring radioactive carbon isotope of mass 14, used in carbon dating and as a tracer in biochemistry. Carbon-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues to date archaeological, geological and hydrogeological samples. There are three naturally occurring isotopes of carbon on Earth: carbon-12, which makes up 99% of all carbon on Earth; carbon-13, which makes up 1%; and carbon-14, which occurs in trace amounts, making up about 1 or 1.5 atoms per 1012 atoms of carbon in the atmosphere. Carbon-12 and carbon-13 are both stable, while carbon-14 is unstable and has a half-life of 5,730 ± 40 years.[3] Carbon-14 decays into nitrogen-14 through beta decay.[4] A gram of carbon containing 1 atom of carbon-14 per 1012 atoms will emit ~0.2[5] beta particles per second. The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between 1955 and 1980 contributed to this pool.

robot

a machine capable of carrying out a complex series of actions automatically, especially one programmable by a computer.

Wheatstone bridge

a null measurement device for calculating resistance by balancing potential drops in a circuit A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements.

transvestite

a person, typically a man, who derives pleasure from dressing in clothes primarily associated with the opposite sex.

dust devil

a phenomenon similar to a tornado that starts on the ground and is not associated with a cloud A dust devil is a strong, well-formed, and relatively short-lived whirlwind, ranging from small to large. The primary vertical motion is upward. Dust devils are usually harmless, but can on rare occasions grow large enough to pose a threat to both people and property. can last for months on mars

biochrome

a pigment synthesized in the metabolic process of living organisms a coloring matter that can be extracted from a plant or animal : a natural pigment.

phosphene

a ring or spot of light produced by pressure on the eyeball or direct stimulation of the visual system other than by light.

phosphor

a solid material that can emit light by fluorescence A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness (> 1 ms), and fluorescent materials, where the emission decay takes place over tens of nanoseconds. Phosphorescent materials are known for their use in radar screens and glow-in-the-dark materials, whereas fluorescent materials are common in cathode ray tube (CRT) and plasma video display screens, fluorescent lights, sensors, and white LEDs. Phosphorus, the chemical element named for its light-emitting behavior, emits light due to chemiluminescence, not phosphorescence.

bimbo

an attractive but unintelligent or frivolous young woman. a young woman indulged by rich and powerful older men

fuel cells

an electrochemical cell that uses replenishable substances such as hydrogen or oxygen or water to produce electricity A fuel cell is an electrochemical cell that converts the chemical energy of a fuel and an oxidizing agent into electricity through a pair of redox reactions

infra-

below, beneath e.g. infrastructure, infrared

Radioisotope Thermoelectric Generator (RTG)

carried in satellites for power A radioisotope thermoelectric generator is an electrical generator that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This generator has no moving parts.

limbic system purpose

controls basic emotions (such as fear, pleasure, and anger) and emotional drives (such as hunger, caring, sex drive, and dominance) The limbic system is a set of structures in the brain that controls emotion, memories and arousal. It contains regions that detect fear, control bodily functions and perceive sensory information (among other things).

vitriol

cruel and bitter criticism Something highly caustic, such as criticism (literally, one of a number of chemicals including sulfuric acid) Sulfuric acid, also known as vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with molecular formula H₂ SO₄. It is a colorless, odorless, and syrupy liquid that is soluble in water and is synthesized in reactions that are highly exothermic.

anisotropic

exhibiting different mechanical properties in response to loads from different directions Anisotropy is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy

smoke and mirrors

false impressions, deceit, trickery the obscuring or embellishing of the truth of a situation with misleading or irrelevant information.

proto-

first; primary original or primitive.

Ad hoc

for a specific purpose or situation when necessary or needed. created or done for a particular purpose as necessary.

Moravec's paradox

high-level reasoning requires very little computation; low-level sensorimotor skills require enormous computation resources (The hard problems are easy, the easy problems are hard.) easy stuff is hard and hard stuff is easy

filariasis

infection of the blood and tissues of healthy individuals by worm embryos or filariae Filariasis is a parasitic disease caused by an infection with roundworms of the Filarioidea type. These are spread by blood-feeding diptera such as black flies and mosquitoes. This disease belongs to the group of diseases called helminthiases. Eight known filarial nematodes use humans as their definitive hosts.

paschen series

infrared The Paschen lines all lie in the infrared band.

arachnoid

like a spider or arachnid. a fine, delicate membrane, the middle one of the three membranes or meninges that surround the brain and spinal cord, situated between the dura mater and the pia mater.

full-fledged

meeting all the requirements to be something: having complete status; well developed completely developed or established; of full status.

meso-

middle, median

defector

one who joins the enemy a person who has abandoned their country or cause in favor of an opposing one. a person who abandons their duty deserter

Radio-frequency identification (RFID)

product tags with tiny chips containing information about the item's content, origin, and destination Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information. Passive tags collect energy from a nearby RFID reader's interrogating radio waves. Active tags have a local power source (such as a battery) and may operate hundreds of meters from the RFID reader. Unlike a barcode, the tags don't need to be within the line of sight of the reader, so it may be embedded in the tracked object. RFID is one method of automatic identification and data capture (AIDC). RFID tags are used in many industries. For example, an RFID tag attached to an automobile during production can be used to track its progress through the assembly line; RFID-tagged pharmaceuticals can be tracked through warehouses; and implanting RFID microchips in livestock and pets enables positive identification of animals.

What is ECG?

recording of the electrical changes that occur in the myocardium during a cardiac cycle electrocardiogram Usually when one visits a doctor for issue's of high blood pressure or symptoms of heart disease, such as chest pain, shortness of breath, an irregular heartbeat or heavy heartbeats our Doctor recommends us an ECG. An ECG test detects and records the heart's electrical activity. This tracing of the electrical signal is the electrocardiogram (ECG). It is possible to record the electrical activity of the heart, using surface electrodes on the body. An ECG records the strength and timing of electrical signals as they pass through the heart. Each electrical signal begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the right atrium, which is the upper right chamber of the heart. The data is recorded on a graph so your doctor can study your heart's electrical activity. Different parts of the graph show each step of the electrical signal's journey through the heart. So, basically an ECG is a simple test to check if your heart is pumping enough blood to run the body without any difficulty.

isometric

same length of or having equal dimensions.

shear waves

seismic waves in which particles of material move back and forth perpendicular to the direction in which the wave itself moves The S-wave is a transverse wave, meaning that, in the simplest situation, the oscillations of the particles of the medium are perpendicular to the direction of wave propagation, and the main restoring force comes from shear stress.

auto-

self, own e.g. automatic, autodidact

craton

the ancient core of a continent, which is tectonically stable a large, stable block of the earth's crust forming the nucleus of a continent. Slave craton is located in canada and was formed 2.5 billion years ago. Old rocks man.

law of reflection

the angle of incidence is equal to the angle of reflection

chemiluminescence

the emission of light from a chemical reaction the emission of light during a chemical reaction which does not produce significant quantities of heat. Phosphorus, the chemical element named for its light-emitting behavior, emits light due to chemiluminescence, not phosphorescence.

carbon 12

the most common natural carbon isotope, of mass 12. It is the basis for the accepted scale of atomic mass units. Carbon-12 is the more abundant of the two stable isotopes of carbon, amounting to 98.93% of the element carbon; its abundance is due to the triple-alpha process by which it is created in stars. There are three naturally occurring isotopes of carbon on Earth: carbon-12, which makes up 99% of all carbon on Earth; carbon-13, which makes up 1%; and carbon-14, which occurs in trace amounts, making up about 1 or 1.5 atoms per 1012 atoms of carbon in the atmosphere. Carbon-12 and carbon-13 are both stable, while carbon-14 is unstable and has a half-life of 5,730 ± 40 years.[3] Carbon-14 decays into nitrogen-14 through beta decay.[4] A gram of carbon containing 1 atom of carbon-14 per 1012 atoms will emit ~0.2[5] beta particles per second. The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between 1955 and 1980 contributed to this pool.

Chinese New Year

the most important Chinese holiday, lasts 15 days and is celebrated in January or February depending on the first full moon in the new year

Magnetopause

the outer boundary of the magnetosphere The magnetopause is the abrupt boundary between a magnetosphere and the surrounding plasma. For planetary science, the magnetopause is the boundary between the planet's magnetic field and the solar wind.

stratification

the process in which sedimentary rocks are arranged in layers the arrangement or classification of something into different groups. Stratigraphy is a branch of geology concerned with the study of rock layers and layering. It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has two related subfields: lithostratigraphy and biostratigraphy.

Electroluminescence

the process of transforming electrical energy directly into light energy luminescence produced electrically, especially in a phosphor by the application of a voltage. Electroluminescence is an optical phenomenon and electrical phenomenon in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emission resulting from heat, a chemical reaction, sound, or other mechanical action.

Mach number

the ratio of an object's speed to the speed of sound By definition, at Mach 1, the local flow velocity u is equal to the speed of sound. At Mach 0.65, u is 65% of the speed of sound (subsonic), and, at Mach 1.35, u is 35% faster than the speed of sound (supersonic).

Condensed matter physics

the study of the properties of matter in the solid and liquid states Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose-Einstein condensate found in ultracold atomic systems. The study of condensed matter physics involves measuring various material properties via experimental probes along with using methods of theoretical physics to develop mathematical models that help in understanding physical behavior.

mesopause

the transition between the mesosphere and the thermosphere the boundary in the earth's atmosphere between the mesosphere and the thermosphere, at which the temperature stops decreasing with increasing height and begins to increase.

Food irradiation

the treatment of foods with gamma rays, X-rays, or high-voltage electrons to kill potentially harmful pathogens and increase shelf life When you go outside for a while, you get a sunburn. That's the UV radiation from the sun damaging the outermost cells on your body. UV irradiation does the same thing to microbes. It mutates their DNA and, because they don't have trillions of spare cells like we do, they die. There is no lasting effect on the food except that there's no more microbial contamination. This type of irradiation can only work on the direct surface it contacts, so it's popular for sterilizing thin sheets of liquids such as juice. The juice is sterilized without any heat treatment.

Thermopause

the upper boundary of the thermosphere The thermopause is the atmospheric boundary of Earth's energy system, located at the top of the thermosphere.[1] The temperature of the thermopause could range from nearly absolute zero to 987.548 °C (1,810 °F).

tropo-

turn, change "turn," "reaction, response," "change," "troposphere,"

forceps

used to pick up or hold small items