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Goal: grow different mold species on different kind of substrates to find out if the same bread mold species will grow on all of them. Do all mold species have the same taste and preferences?!
Hypothesis: Snails will move slower on the dry and rough surface and faster on the smooth or wet surface. Even if the surfaces has the same roughness snail will travel faster on wet surface.
A few transparent plastic containers.
Different kind of food - fruits, bakery, vegetables, chips will work well. Do not try to grow mold on meat. Mold is mostly vegetarian.
In our test case we used orange, kiwi fruit, cabbage leaf, bread and biscuits. Bread is well known favorite mold food, everyone know that. We wanted to check if the bread mold will like biscuits - they made from the similar products they also have sugar which should be great food for the mold. Our other substrates are fruits and vegetables. Fruits have a lot of moisture and sugar which should be good for the mold, cabbage has moist leaves.
We did't use any meat because it contains a lot of protein. Bacteria will grow fast on protein causing extremely bad smell of decomposing meat.
Put your samples in the containers and cower with lids. Leave in the dark warm place. Check every day for the mold growth. Write down any changes that you notice during your observations. Try to count mold colonies, describe their shape and color, what happens to them as they grow.
We put our substrate samples in 4 plastic containers and sprinkled it with water.
Air always contains microscopic dust particles. Some of this particles are mold spores, some are soil particles that also can contain mold spores. Air current moves the particles from place to place and this is how mold spread. When such particles land on our wet substrate they will stick to it and (hopefully) contaminate it with spores.
We have left our samples open for 30 minutes. Some mold spores already existed on the fruits but we needed to let some spores land on the fresh cut of bread and fruits. Biscuits also needed some exposure to the open air.
After half of hour of exposure we closed containers with lids and put it in a warm dark place.
If you repeating this experiment, make sure that container lid closed tightly. If you want to open it to check the mold do it EXTREMELY carefully. Mold spores lift off with the smallest breath and heavily contaminate your environment. You don't want to get sick or get an allergy! After inspection close container tightly. When experiment finished, Put containers in the plastic bag and dispose it. Do not open the lids. Do not try to wash the containers.
Next few days we were checking them for the signs of mold.
After one week of incubation we've got plenty of it!
Look at the following pictures. Bread produced the biggest amount of mold colonies of the different species (Fig. 1). Some of the colonies belong to the same species. We can not tell scientific names because with mold you need microscopic study to do that accurately, but we can tell that we have at least 5 species in multiple colonies (Fig. 2).
Fig. 1: Bread mold experiment results
We outlined the biggest colonies for each species. White fluffy cotton-like bread mold grows faster then others and very aggressive. It can consume other colonies but it does not seem to produce a lot of spores. The other main 2 mold species are green and yellow-gray. There are also few small colonies of bright yellow color. This type of colony grew only on the bread sample.
Many colonies joined, some colonies are consumed by other and it's hard to count their exact number and accurately calculate how many spores contaminated the bread. However there are more then 30 colonies growing on this sample.
Fig. 2: Bread mold colonies outline.
The kiwi fruit shows very different growth pattern. On the cut surface we can see 2 dominating colonies - green and yellow and few other smaller colonies. The surface of the skin is pretty tough and almost not affected by mold. The most successful species that grew on kiwi fruit was "green mold". The cabbage resists to the mold grows very well - no sign of mold so far.
Fig. 3: Mold colonies on Kiwi fruit
Unlike Kiwi fruit, orange skin shows heavy mold grows and the cut is less affected. It looks like mold does not like orange juice!
Fig. 4: Mold on the orange.
Biscuits did not show any mold grows at all even in 3 week time!
Observing mold growth we can tell that different kinds of mold grow better on different substrates. The speed of the grows depends on the moisture, amount of nutrients and resistance of the substrate. Biscuits - the most dry substrate which also contain anti-mold preservatives did not show any growth. Cabbage leaf show the best resistance to the mold growth among the other tested substrates.
2. Mold in Your Room.
Do you have mold in your room? No?
Let's find out.
Goal: prepare sterile substrate for the mold growth. Try to find out how many mold spores per hour lands on 1 square meter of the surface in your room.
For this project you'll need to learn how to prepare "medium" - sterile nutrient substrate made specifically to grow microorganisms such as mold or bacteria.
You can make it yourself or buy reedy-to-go sterile petri dishes.
Home-made media could be prepared from different components. Different type of microorganisms prefer different media. Mold media can be prepared from potato, banana, starch, oatmeal and cornmeal and even such exotic thing as rabbit dung.
Starch/gelatin or starch/agar medium is the simplest that you can do at home. Plastic containers similar to what we used in the mold garden project will serve as a big petri dish.
Prepare sterile medium and pour it into 4 containers.
Close containers and wait until medium is set.
Open container lids and close them one at a time each 5 minutes so that you have container that was open 5min another one 10 min, etc.
Wait a few days and calculate mold colonies on the medium.
3. Mold Wars
Goal: isolate individual mold species from environment (air, soil, water) and grow a clean strains of mold. Inoculate medium in petri dish with different mold species and find which species will win the fight for resources.
When you have multiple colonies that grew from the spores on sterile substrate you can try to grow a clean line - individual species of mold and compare some of their qualities - such as growth rate, "aggressiveness", tolerance to the different substances, light, etc.
To do this project you 'll need to learn how to do sterile transfer of the mold spores, and experiment with different cultures.
4. Water Purification Experiment.
Depending on what you need there are many ways to clean the water. The simplest way is filtration with some kind of porous material (cloth or cotton in the very simple case). This kind of purification provide basic purification filtering out dust, dirt, sand and other macroscopic particles you may find in the water. It will also filter out small round worms and perhaps large single cell organisms. You would be surprised to see how many of them can be in single drop of some pond water!
However this kind of purification would not clean water from bacteria, viruses and dissolved minerals.
In this 5th grade science project we will study which purification method can better purify salted water.
At home you can use 2 methods to do that - distillation and crystallization.
Salt and/or soda.
Glass and small bowl.
You'll need to create water distiller and water crystallizor.
Here you'll find pretty cool video that explains in details how to make a simple sun powered water distiller.
For crystallizer you'll just use a plastic bowl. Fill it with salty water and put it in the freezer. Check it from time to time. When you see that ice filled half of the bowl in the bowl, collect it and put in the clean glass. Don't wait until all the water in the bowl get frozen.
When enough water is distilled and crystallized, compare the results. You can taste the water, you can also put equal amount of water on the clean surfaces (plates, glass, polished table will work even though using polished table for experiments is not a good idea). Wait until water dries. All salts remaining in the water will stay on the surface and you can judge which water sample was cleaner. | <urn:uuid:56e98dfd-f1c0-4837-9cf3-d40154601fe6> | 3.703125 | 1,784 | Tutorial | Science & Tech. | 62.869176 |
Stereographic projections are created by projecting from a point at one
end of the diameter in a circle to a projection plane which sit tangential
to the other end of the diameter. This situation is clearly depicted in
Figure A where the light source comes from point A with white rays radiating
out of it. Geometrically, the light source sits on the bottom end of diameter
AB. In terms of geography, the light source sits on the south pole of
the earth with the projection plane CI on the north pole, thus making
the projections on this plane a polar projection. Visually, one can think
of the stereographic projection as being created by the shadows casted
upon the projection plane CI by the parallels and meridians.
With the yellow lines representing parallels and the angle the blue lines
makes withe the equator representing angular distance away from the equator
EF, shadows of parallels are located at the intersection of the light
rays with the plane of projection such as C, B, D, E, F, G, H, and I.
As noted in the picture, these rays all goes through the same intersection
point made by the parallel with the circle. When looking upon this plane,
latitudes will appear as circles whose radius is equal to the distance
the polar axis AB is away from such intersections as C, B, D, E, F, G,
H, and I as illustrated in Figure B. Mathematically, this distance can
be calculated using circle geometry. Referring to Figure A, if an arbitrary
latitude JK is chosen, its angular distance is <EOJ. Because the polar
axis and the equator are perpendicular to each other, <EOJ and <BOJ
are complementary angles. As such <BOJ is also known as a co-latitude.
In other words, <BOJ = 90° - <EOJ. A similar situation occurs
on the supplementary side of the latitude. Thus, <FOK=angular distance
of latitude and <KOB = co-latitude. Therefore, <KOB=<BOJ and
<EOJ=<FOK. Utilizing a fact from circle geometry, there is a central
angle <JOK subtended by the arc JK. Since <JAK is also subtended
by the same arc JK, but touching the side of the circle, the relationship
between <JOK and <JAK is as follows: <JAK= 1/2 <JOK. Because
JK is perpendicular to the polar axis BA which goes through the center
of the circle, BA bisects JK and similarly <JOK and <JAK. This is
because <JAK and <JOK are opposite angles to the bisected latitude.
The relationship <JAK = 1/2 <JOK becomes <JAB+<KAB=1/2 (<JOB+<KOB).
Since <KAB = <JAB and <JOB = <KOB, 2 <JAB = 1/2 (2 <JOB)
therefore <JAB=1/2<JOB. With AB equivalent to the diameter of the
earth or 2 radius and the plane CI tangential to the circle, therefore,
<CBO is a right angle. Thus the following relationship can be formed:
tan (<JAB) = JB (radius of the latitude) / circle's diameter. In other
words, radius of the latitude = 2 circle's radius * tan(1/2<JOB). In
conclusion, radius of latitude = radii * tan(co-latitude). Since tangent
reaches infinity at 90°, the polar stereographic projection cannot
reveal an entire hemisphere. Another interesting fact about the stereographic
polar projection is that smaller latitudes are farther away from the center
point of the projection (which represents the north pole) at the point
where the polar axis intersects the projection plane.
By visually imagining the meridians from a birds eye view, one can imagine
that the meridians, which is the semi circle following the shape of the
earth from the poles, will be projected as the straight radius of the
outer most latitude as seen in Figure C. These equally spaced radius are
rotated around the center with the desired angular interval. Therefore,
the number of meridians with angular distance n° apart from each other
would have 360°/n° number of meridians. | <urn:uuid:971b1405-9798-4dd0-8c6d-361ccbe6e516> | 4.5625 | 949 | Academic Writing | Science & Tech. | 48.899724 |
A SUPERNOVA seen in 2005 may be a new type of cosmic explosion. What's more, similar explosions may have scattered antimatter throughout our galaxy.
"SN 2005E" exploded in a galaxy 100 million light years away. A team led by Hagai Perets at the Weizmann Institute of Science in Rehovot, Israel, has concluded that it does not look like either of the well-known kinds of supernova.
The most frequently observed form is a core-collapse supernova, which happens after a massive young star has formed a large core of iron that collapses under its own gravity, releasing radiation that blows the outer layers of the star apart. They almost always occur in regions where massive new stars are forming. By contrast, SN 2005E was in the dark outskirts of its galaxy, where few new stars are forming. Core-collapse supernovae also spit out much more debris than SN 2005E did. ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:4d9a137c-fca4-4730-b251-507f4c92d80e> | 3.546875 | 219 | Truncated | Science & Tech. | 55.452267 |
William R. Sharp, a research professor at the Colorado School of Mines in Golden, is often asked to identify rock specimens. Here is his advice.
The quick answer is that your rock is most likely not a meteorite at all. This is based upon our experience with material brought to us for identification, assumed by the owner to be a meteorite.
Image: Views of the Solar System
Meteorites are in fact very rare occurrences. The total mass of meteorites in museums or in collectors' hands is estimated to be far less than the total yearly world production of gold (2,000 or so tons). Experts estimate between 20,000 to 100,000 tons of material from space collides with the Earth each year; however, most of it burns up in the atmosphere, becomes atmospheric dust, lands in the ocean, or is simply never found.
One opportunity for finding a meteorite is to observe a fireball and recover the resulting impact debris, which survives the explosive encounter with the Earth's atmosphere. Fireballs are rather common occurrences. However, recovering space rocks resulting from a fireball is a much rarer event, but it does occur and there are recorded incidents where homes, cars, and mailboxes have received direct hits.
A larger number of meteorites are "finds" not directly related to an observed fall. The best areas for collecting meteorites are where they "stand out" against their natural background such as in deserts or in Antarctic glacial snows. Antarctica, for example, is a particularly rich source of meteorites because they are pushed up onto the surface of the ice. The famous Allan Hills meteorite that some believe contains evidence of life on Mars was found there.
In general, the appearance and feel of a "strange looking rock" is the best indicator that it might indeed be a meteorite. Consider the following questions:
Does the rock have a black or brown sooty-looking exterior? Does the rock have a density greater than normal? Is the sample metallic or does it contain pieces of metal? Is the material different from other rocks in the area? Does the rock have a strange "fish-eye" looking texture?
An answer of yes to any of the above questions is an indication that you may be in possession of a very unique and rare rock. Further investigation may be warranted.
A recent fall will have a textured exterior resembling a charred orange skin, referred to as a "fusion crust," which results from oxidization of the object as it passes through the atmosphere. When a meteorite lies around on the Earth's surface for an extended period, the fusion crust and interior minerals will become weathered, complicating the identification process.
Most meteorites that actually crash into the Earth's surface contain metallic iron, which can be visually recognized and easily detected with the assistance of a pocket magnet. Nickel also is normally always present in iron meteorites. To identify nickel in a specimen, however, will require laboratory testing.
Meteorites contain no hazardous materials, which may be harmful to humans. This is, of course, unless, one becomes a direct target of an incoming meteorite. Because there are no recorded incidents of humans being killed by falling space rocks, we can be reassured meteorite falls are indeed rare.
Chemically and physically meteorites differ from most ordinary Earth rocks. However, no new elements or life forms have so far been detected in meteorites. Organic compounds, including the amino acids necessary for life, have been identified in some very special types of space rocks. Some researchers claim the Martian meteorite contains fossilized bacteria, but the scientific community has not yet unanimously endorsed the claim. | <urn:uuid:02fdc5a7-1ff2-4382-862e-3e74619b7977> | 3.671875 | 745 | Knowledge Article | Science & Tech. | 36.587623 |
Sunset on an Alien World
This artist's animation illustrates what the night sky might look like from a hypothetical alien planet in a star system with an asteroid belt 25 times as massive as the one in our own solar system.
NASA's Spitzer Space Telescope found evidence for such a belt around the nearby star called HD 69830, when its infrared eyes spotted dust, presumably from asteroids banging together. The telescope did not find any evidence for a planet in the system, but astronomers speculate one or more may be present.
The movie begins at dusk on the imaginary world, when HD 69830, like our Sun, has begun to set over the horizon. Time is sped up to show the onset of night and the appearance of a brilliant band of light. This light comes from dust in a massive asteroid belt, which scatters sunlight.
In our solar system, anybody observing the skies on a moonless night far from city lights can see this light. Called zodiacal light and sometimes the "false dawn," it appears as a faint band stretching up from the horizon when the Sun is about to rise or set.
The zodiacal light in the HD 69830 system would be 1,000 times brighter than our own, outshining even the disk of our Milky Way galaxy (shown perpendicular to the asteroid-belt light).
Browse Videos in Science Animations
This artist's animation illustrates how silicate crystals like those found in comets can be created by an outburst fr... | <urn:uuid:df29a25b-6de3-4301-a62e-fb192ed8fbb8> | 3.34375 | 301 | Truncated | Science & Tech. | 54.689962 |
Regarding the property of the "strong force", here's some mainstream spiel from our good ol' friend Wikipedia:-
The contemporary strong force is described by quantum chromodynamics (QCD), a part of the standard model of particle physics. Mathematically, QCD is a non-Abelian gauge theory based on a local (gauge) symmetry group called SU(3).
Quarks and gluons are the only fundamental particles which carry non-vanishing colour charge, and hence participate in strong interactions. The strong force itself acts directly only upon elementary quark and gluon particles.
All quarks and gluons in QCD interact with each other through the strong force. The strength of interaction is parametrized by the strong coupling constant. This strength is modified by the gauge color charge of the particle, a group theoretical property.
The strong force acts between quarks.
The residual effect of the strong force is called the nuclear force. The nuclear force acts between hadrons, such as mesons or the nucleons in atomic nuclei. This "residual strong force", acting indirectly, transmits gluons that form part of the virtual pi and rho mesons, which, in turn, transmit the nuclear force between nucleons.
The residual strong force is thus a minor residuum of the strong force which binds quarks together into protons and neutrons. This same force is much weaker between neutrons and protons, because it is mostly neutralized within them, in the same way that electromagnetic forces between neutral atoms (van der Waals forces) are much weaker than the electromagnetic forces that hold the atoms internally together.
With regard to "forces" which attract and repel; it seems that ultimately there may only be one force in space that governs the behaviour of matter. How matter is arranged and configured in spatial dimensions - certainly seems to govern the strength of whatever repulsive or attractive "forces" are present. Some may call it "electricity" or "gravity" or "weak force" or whatever - depending on the context. But I personally feel that there is probably only one force out there. I may be wrong, of course. I don't pretend to know how this beautiful universe works. | <urn:uuid:872cd7a2-50ab-44af-aacb-c18b9bf6ccc9> | 2.96875 | 461 | Comment Section | Science & Tech. | 43.716554 |
Atmospheric Science Literacy - Essential Principle 2
Energy from the Sun drives atmospheric processes.
Fundamental Concept 2.1
Earth receives energy in the form of electromagnetic radiation from the Sun. Some of this solar energy is absorbed by the atmosphere, some is scattered back to space, and some is transmitted through the atmosphere to be absorbed or reflected by Earth's surface. The solar energy reflected by Earth's surface is absorbed, scattered, or transmitted by the atmosphere.
Fundamental Concept 2.2
Energy from the Sun is transformed into other forms of energy in the Earth System. In the atmosphere these other forms include thermal energy of gas molecules, the kinetic energy of wind, and the latent heat of evaporation stored in water vapor.
Fundamental Concept 2.3
On human time scales, the energy emitted by the Sun is nearly constant, varying only very slightly due to solar activity. The amount of solar energy received at a point on Earth's surface varies due to Earth's spherical shape, its daily rotation about its tilted axis, its annual revolution around the Sun, and the slight elliptical shape of Earth's orbit, leading to important cycles such as day and night, and the seasons. In addition, cloud cover and aerosols can reduce the amount of solar energy that reaches Earth's surface.
Fundamental Concept 2.4
Solar energy drives many chemical, biological, and physical processes that affect Earth's atmosphere. These include processes such as photosynthesis, evaporation of liquid water to produce water vapor, formation of smog, and the formation and destruction of ozone.
Fundamental Concept 2.5
Earth also emits energy in the form of electromagnetic radiation. Almost all of the energy emitted comes from the solar energy absorbed by Earth's surface. This terrestrial energy is absorbed by atmospheric trace gases, such as water vapor, carbon dioxide, and other gases in Earth's atmosphere. It may be reemitted from the atmosphere, either to space, where it is lost to the Earth System, or back to Earth, where it is again absorbed, producing a "Greenhouse Effect". This natural Greenhouse Effect is necessary for life to exist on Earth. | <urn:uuid:ae73a57e-8581-4207-954c-e15073cbc5f5> | 3.453125 | 438 | Knowledge Article | Science & Tech. | 36.968235 |
What are nuclear wastes and how are they managed?
The most significant high-level waste from a nuclear reactor is the used nuclear fuel left after it has spent three years in the reactor generating heat for electricity. Low-level waste is made up of lightly-contaminated items like tools and work clothing from power plant operation and makes up the bulk of radioactive wastes. Items disposed of as intermediate-level wastes might include used filters, steel components from within the reactor and some effluents from reprocessing.
By Radioactive Content
High Level Waste
Intermediate Level Waste
Low Level Waste
Generating enough electricity for one person produces just 30 grams of used fuel each year.
High level wastes make just 3% of the total volume of waste arising from nuclear generation, but they contain 95% of the radioactive content. Low level wastes represent 90% of the total volume of radioactive wastes, but contain only 1% of the radioactivity.
Managing used fuel
Used nuclear fuel is very hot and radioactive. Handling and storing
it safely can be done as long as it is cooled and plant workers are
shielded from the radiation it produces by a dense material like
concrete or steel.
Water can conveniently provide both cooling and shielding, so a
typical reactor will have its fuel removed underwater and
transferred to a storage pool. After about five years it can be
transferred into dry ventilated concrete containers, but otherwise
it can safely remain in the pool for up to 50 years.
But this used fuel is also a valuable resource, and 96% of it
can be recycled. Currently, but means that the sustainability of nuclear power is
enhanced. In this case about 1% of the fuel is recycled
promptly into mixed oxide fuel (MOX), the rest is usually stored
for the future while about 3% of the original mass remains as waste
to be disposed of.
The high-level wastes (whether as used fuel after 50 years cooling, or the separated 3% of such fuel) will be disposed of deep underground in geological repositories.
Intermediate and low-level wastes
low-level wastes are disposed of closer to the surface, in many
established repositories. Low-level waste disposal sites are
purpose built, but are not much different from normal municipal
Nuclear power is not the only industry that creates radioactive wastes. Other industries include medicine, particle and space research, oil and gas, and mining - to name just a few. Some of these materials are not produced inside a reactor, but rather are concentrated forms of naturally occurring radioactive material.
Civil nuclear wastes from nuclear power plants have never caused any harm, nor posed an environmental hazard, in over 50 years of the nuclear power industry. Their management and eventual disposal is straightforward.
One characteristic of all radioactive wastes which distinguishes
them from the very much larger amount of other toxic industrial
wastes is that their radioactivity progressively decays and
diminishes. For instance, after 40 years, the used fuel removed
from a reactor has only one thousandth of its initial radioactivity
remaining, making it very much easier to handle and dispose of.
The categorization - high,
intermediate, low - helps determine how
wastes are treated and where they end up. All radioactive waste facilities are designed
with numerous layers of protection to make sure that the environment remains
protected for as long as it takes for radioactivity to reduce to background
levels. Low-level and intermediate
wastes are buried close to the surface. For low-level wastes disposal is not
much different from a normal municipal landfill. High-level wastes can remain
highly radioactive for thousands of years. They need to be disposed of hundreds
of metres underground in heavily engineered facilities built in stable
geological formations. While no such facilities currently exist, there
feasibility has been demonstrated and there are several countries now in the
process of designing and constructing them. | <urn:uuid:ad7085de-5d65-41b4-8460-750ea1e3f029> | 4.125 | 817 | Knowledge Article | Science & Tech. | 30.072111 |
Finding secret messages in DNA microdots
Jarvis, S.A., Mirsky, J.S., Peden, J.F. and Saunders, N.J. (2001) Finding secret messages in DNA microdots. Technical Report. Department of Computer Science, Coventry, UK.
- Published Version
A DNA microdot offers a novel way in which to communicate secret information. It is an extension of the more traditional microdot, a greatly reduced photograph of a secret document which replaced a full stop somewhere in an innocent-looking letter. The DNA microdot appears to be the secure modern alternative, exploiting the complexity of DNA in which a coded secret message is hidden. An enemy can only unlock the secret information by first knowing that an intercepted letter is impregnated with microdot DNA, and secondly by finding the message amongst a huge amount of background DNA used to mask the secret information. Using software developed to identify horizontally acquired DNA, we show that this apparently insurmountable task is in fact possible. With the increased speed of DNA sequencing, the information contained in the DNA microdot is far from secure.
|Item Type:||Monograph (Technical Report)|
|Subjects:||Q Science > QA Mathematics > QA75 Electronic computers. Computer science|
|Divisions:||Faculty of Science > Computer Science|
|Depositing User:||Mr Ebrahim Ardeshir|
|Date Deposited:||14 Dec 2011 14:57|
|Last Modified:||01 Nov 2012 18:06|
Actions (login required) | <urn:uuid:b24b3330-89ff-4f6f-b1ba-37e432d68c5f> | 2.796875 | 326 | Academic Writing | Science & Tech. | 39.192683 |
The 10 members of the GammeV experiment formed their collaboration in April, 2007, to investigate a claim that an Italian experiment called PVLAS had discovered an axion-like particle. The axion is a hypothetical particle that could cause light to behave strangely in a magnetic field, causing its polarization to rotate. It is one of the primary candidates for dark matter.
In the first phase of the experiment, physicists shot a laser through a magnet onto a mirror. The mirror was mounted on a welded cap that blocked all light. They wanted to know whether a particle of light, or photon, could be converted into an axion particle that could pass through the mirror and light-tight cap and become a photon again on the other side.
They fired the laser 6 million times in search of the new particle, which statistically should have appeared hundreds of times as regenerated photons. But they found no evidence that the light passed through the cap. This refuted the claims of the PVLAS experiment.
In its second run, the GammeV experiment searched for chameleon particles, hypothetical particles the properties of which are determined by their environment. Physicists theorize these particles may be responsible for dark energy. The experiment searched for chameleon particles by looking for a glow they should emit when they become trapped in a region with a high magnetic field and slowly decay into detectable photons. The collaboration did not observe a glow in this run of the experiment.
Members of the collaboration would like to upgrade their original axion study for the detector's third run. | <urn:uuid:68501015-dc36-449d-bed5-6b9ccf4b5f18> | 3.59375 | 316 | Knowledge Article | Science & Tech. | 40.295113 |
Its easy to get current directory in Java by using built-in system property provided by Java environment. Current directory represent here the directory from where "java" command has launched. you can use "user.dir" system property to find current working directory in Java. This article is in continuation of my earlier post on Java e.g. How to load properties file in Java on XML format or How to parse XML files in Java using DOM parser and Why Java doesn’t support multiple inheritance . If you haven’t read them already, You may find them useful and worth reading. By the way here is a quick example of finding current directory in Java:
How to get current directory in Java with Example
If you run above program from C:\Test it will print C:\Test as current working directory
If you run it from C:\ then it will print C:\ as current working directory as shown in below example
That's all on how to get current directory in Java. Its easy just remember name of system property "user.dir" which gives directory from where java command has been executed.
Some other Java tips you may like | <urn:uuid:b901bb96-7876-4c7d-a988-41f8152d86a5> | 3.21875 | 232 | Tutorial | Software Dev. | 52.432526 |
See also the
Dr. Math FAQ:
0.9999 = 1
0 to 0 power
n to 0 power
0! = 1
dividing by 0
Browse High School Number Theory
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Infinite number of primes?
Testing for primality.
What is 'mod'?
- Divisibility Proof [03/09/1998]
Divisibility of any given positive integer by another built from only 1's
- Divisibility Proof [10/26/1999]
How can I prove that (n^5-n) is divisible by 30, and (n^7-n) is divisible
by 42, without using induction?
- Divisibility Proof by Euclidean Algorithm [02/20/2003]
Let a and b be integers. Suppose that (a,b) = 1 (assuming the gcd
exists). Prove that there exist integers x and y such that ax + ay =
- Divisibility Proof for Odd Integers [02/13/2002]
Prove that for all odd integers N, N^3 - N is divisible by 8.
- Divisibility Rule for All Divisors [11/07/1999]
Is there a theorem for figuring out divisibility rules for all natural
- Divisibility Tests to Find the Smallest Prime Factor of a Number [02/02/2006]
How can I quickly find the smallest positive prime divisor of 1633
without having to do lots of divisions to check the possibilities?
- Division by Zero: Indeterminate or Undefined? [02/23/2002]
I'm having some trouble understanding division by zero.
- Division of Large Numbers [04/28/1998]
What is the remainder when 7^100 is divided by 13? Give a general
strategy and an explanation.
- Does Infinity Exist? [11/15/2001]
What proof do we have that infinity actually exists?
- Do Rational and Irrational Numbers Alternate? [10/13/2000]
If any two non-equal real numbers "contain" an irrational, and any two
non-equal real numbers "contain" a rational, do rational and irrational
- Double Factorial [02/22/2002]
Can you tell me what two ! marks mean in factorial questions?
- Dragon's Tail [04/01/2003]
An n-dragon is a set of n consecutive positive integers. The first
two-thirds of them is called the tail, the remaining one-third the
head, and the sum off the numbers in the tail is equal to the sum of
the numbers in the head. Find the sum of the tail of a 99,999-dragon.
- Duotrigesimal (Base 32) Numbers [06/11/1999]
A unique and interesting use for base 32 or "duotrigesimal" numbers.
- Egyptian Fractions [06/11/2001]
The Egyptians wrote all their fractions as a sum of different fractions
with a numerator of 1. I need to find a way to work out what fractions
should be added together...
- e^pi vs. pi^e [03/20/2002]
Which is greater, e^pi or pi^e? I would like to have a simple proof.
- Equality Properties and What They Really Mean [07/30/2008]
In class we are shown how to square both sides of an equation or take
the square root of both sides, but is there a rule like the addition
property of equality that formally says those are valid steps?
- Equations with a Common Root [08/22/2001]
Find all real numbers a such that the equations x^9+ax^7-(a-3)x^6-1/
2x^2+1=0 and 2x^5+2ax^3-(2a-6)x^2+1=0 have a common root.
- Equations with Rational Expressions in Two Variables [12/07/2002]
Determine all positive integers a and b that satisfy the equation: 1/a
+ a/b + 1/ab = 1.
- Equation without a Solution [11/14/2001]
What is the solution to the equation sqrt(x) = -2 ?
- Equation with Two Exponential Terms [06/27/2009]
Find all ordered pairs (a,b) for which 3^a + 7^b is a perfect square.
- Equivalent Sums of Squares [07/20/2002]
Is a^2 + b^2 = c^2 + d^2 possible where a, b, c, d are positive real
integers and where the pairs of squares are not identical?
- Error: Division by Zero [02/12/2001]
How can I explain to my third grader that a number divided by zero is
undefined? The school calculator gives the answer 0/E, and the Windows
calculator gives positive infinity.
- Euclidean Algorithm [10/13/1997]
Can you tell me what Euclid's theorem is in layman's terms?
- Euclidean Algorithm [01/25/2003]
Given two nonzero positive integers a and b, each at most 100 digits
long, use the Euclidean algorithm process to find an example of (a,b)
such that they produce the longest possible chain.
- Euclidean Algorithm and Linear Equations [11/03/2003]
Could you please explain step by step how to use the Euclidean
Algorithm to solve a linear equation and find x and y integers?
- Euclidean Algorithms [3/13/1996]
What is the Euclidean algorithm? What is a "constructible" number? What
can you tell me about Diophantine equations?
- Euclid's Extended Algorithm [09/16/2001]
Can you please state for me the steps of Euclid's extended algorithm in
- Euclid's Proof on the Infinitude of Primes [10/31/1995]
Which Greek mathematician proved that there is no greatest prime number?
- Euler Phi Function [02/24/2002]
If p and q are prime, investigate: phi(p^n * q^m).
- Euler's theorem [7/2/1996]
How do I find the inverse of a modulo m using Euler's theorem?
- Even and Odd Numbers in Base 5 [02/02/2002]
How can you tell if a number in base 5 is even or odd?
- Even-Digit Palindromes Divisible by 11 [12/08/1997]
Can it be proved that every even-digit palindromic number is divisible by
- Even - Odd Handshake Problem [05/11/2000]
How can I prove that the number of persons who have shaken an odd number
of hands is even?
- Even or Odd in Base 5? [09/23/1999]
Is there a way to find whether a number written in base 5 is even or odd
without first converting it to base ten?
- Explaining the Euclidean Algorithm [10/27/1998]
In the Euclidean Algorithm (or the Division Algorithm), why is the last
divisor the greatest common factor?
- Exponential Diophantine Equation [06/24/2005]
Find three integers a,b,c > 1 such that a^a * b^b = c^c.
- Exponential Proof [03/06/2003]
Let a, b, c be positive integers such that a divides b^2, b divides
c^2, and c divides a^2. Prove that abc divides (a + b + c)^7.
- Exponential Series Proof [05/05/2001]
Given e^x greater than or equal to 1 + x for all real values of x,and
that (1+1)(1+(1/2))(1+(1/3))...(1+(1/n)) = n+1, prove that e^(1+(1/2)+
(1/3)+...+(1/n)) is greater than n. Also, find a value of n for which
1=(1/2)+(1/3)+...+(1/n) is greater than 100.
- Factorial Base and Base 10 [11/02/2001]
Let n be a number written in base 10, which also has an interpretation in
factorial base. Let m be the value of its interpretation in factorial
base. What is the greatest n for which m is equal to or less than n?
- Factorials Can't Be Squares [02/11/2000]
Can you prove that the factorial of a number (greater than 1) can never
be a perfect square? | <urn:uuid:594e42f3-a263-48ed-9bcb-5f31deb10b6c> | 3.171875 | 1,954 | Q&A Forum | Science & Tech. | 78.784412 |
Find the number of integers from 1 to 10,000 which are divisible by either 13 or 51
Welcome to Math Help Forum!
In the same way, you can find the number of integers that are divisible by .
Add this number to . Then you will need to subtract the number of integers that are divisible by , because they will have been counted twice. (Note that , so and have no common factors.)
Can you complete this now? | <urn:uuid:83225f3e-369d-4875-b6d5-8e0783c0f5da> | 3.203125 | 94 | Q&A Forum | Science & Tech. | 71.530965 |
|Publisher version (open access)||977 KB||Adobe Acrobat PDF||View/Open
Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/34114
- The geomorphology and hydrology of Saline Lakes of the Middle Paroo, Arid-zone Australia
Timms, Brian V.
- Sixteen subsaline (0.5 – 3 gL⁻¹) and saline lakes (> 3 gL⁻¹) of the Paroo have been studied for periods of up to 18 years. Many were formed by drainage routes being blocked by dunes, some lie in dune swales, some lie at the edge of the Paroo floodplain where alluvial sediments are thinner, and Lake Wyara lies in a depression on a fault line. All developed further by deflation and owe their form to wind-induced currents and wave action shaping shorelines. Most saline lakes have lunette dunes on the eastern shore, and many larger ones have migrated westwards. Lakes of low salinity have sandy beaches and no, or poorly developed, lunettes. Lakes with N-S axes have the southeastern corner cut off by spits generated by currents induced by northwesterley winds. A few lakes are filling with sediment derived from the overgrazing of catchments associated with European settlement. Larger lakes with inflowing streams fill in El Niño years, then dry over the next few years. Smaller lakes without surface inflows may fill a few times in wet years but dry quickly. Most lakes remain dry in La Nina years. Salinity regimes fluctuate widely and, while instantaneous faunal lists may be depauperate, cumulative species lists can be long. However, lakes which normally are fresh, but become saline in their final stage of drying, develop only a limited saline lake fauna.
- Proceedings of the Linnean Society of New South Wales Vol. 127, p. 157-174
- Linnean Society of New South Wales
- Resource Type
- journal article
- Full Text | <urn:uuid:42ff5d14-8187-4da4-aded-4ce784b8cd00> | 2.9375 | 435 | Academic Writing | Science & Tech. | 49.502237 |
This image highlights major upwelling areas along the world's coasts in red. Upwelling occurs when winds blowing across the ocean surface push water away from an area and subsurface water rises up from beneath the surface to replace the diverging surface water. These subsurface waters are typically colder, rich in nutrients, and biologically productive. Therefore, good fishing grounds typically are found where upwelling is common. For example, the rich fishing grounds along the west coasts of Africa and South America are supported by year-round coastal upwelling. | <urn:uuid:0a5e11bf-f1bc-4a16-b295-ccc34a24f9ab> | 3.734375 | 111 | Knowledge Article | Science & Tech. | 29.384636 |
The high-temperature oxidation of silicon carbide and chemically vapor-deposited silicon carbide coated graphite
One of the major challenges in the development of protective SiC coatings for graphite is preventing oxidation of the graphite substrate when cracks have formed in the SiC coating. There is evidence that the addition of boron results in the formation of a low melting oxide which either flows and covers the exposed carbon substrate or reacts with the silica scale to form a liquid borosilicate.^ The effect of boron additions on the oxidation of SiC has been investigated by comparing the oxidation behavior of sintered $\alpha$-SiC, which contains 0.5 wt% boron, with that of high purity CVD SiC. The boron in sintered $\alpha$-SiC does not significantly affect the growth rate of either amorphous silica or cristobalite between 1400$\sp\circ$C and 1600$\sp\circ$C, but does result in the formation of bubbles in the silica scale formed between 1230$\sp\circ$C and 1550$\sp\circ$C.^ The effect of boron on the oxidation of graphite through cracks in SiC coatings has been investigated by comparing the oxidation behavior of graphite coated with SiC, with boron-containing coatings and with double layer coatings consisting of a SiC outer layer and a boron-containing interlayer. Above 900$\sp\circ$C, the oxidation of cracked SiC coated graphite is limited by diffusion through the cracks, but below 900$\sp\circ$C, the oxidation rate is influenced by the chemical reaction. Boron-containing coatings alone decrease the oxidation rate of graphite. However, SiC coatings with a boron-containing interlayer can provide oxidation protection of graphite for up to 9 days at 1500$\sp\circ$C by forming a liquid borosilicate which covers the graphite substrate. ^
Engineering, Materials Science
Jeffrey Wayne Fergus,
"The high-temperature oxidation of silicon carbide and chemically vapor-deposited silicon carbide coated graphite"
(January 1, 1990).
Dissertations available from ProQuest. | <urn:uuid:3ba2ecd0-a171-4926-a831-5b5fd8d29371> | 2.75 | 483 | Academic Writing | Science & Tech. | 26.727604 |
In 2001 Ignacio Chapela, an ecologist from the University of California, Berkeley, and co-author David Quist published a highly controversial paper in Nature that appeared to show that genetically engineered genes used in genetically modified (GM) corn (maize) was spreading from GM cornfields in Mexico into traditional corn crops. This set off a firestorm where proponents of GM agriculture declared the paper fatally flawed, pointing out some apparent errors. Accusations of agribusiness conflicts of interest were traded with those of political agendas. Nature subsequently published an “editor’s note” stating the journal felt the paper’s data were insufficient to support its conclusions. The journal has been careful to say that the editor’s note was not the same as a retraction, although advocates of GM crops have claimed it was. A subsequent paper in Proceedings of the National Academy of Sciences (PNAS) by Ohio State plant ecologist Allison Snow failed to find transgenes in maize in the same areas sampled by Chapela and Quist, although questions about that paper were raised on the grounds of statistical power. Now the latest chapter, a forthcoming paper in the journal Molecular Ecology by yet another researcher, Elena Álvarez-Buylla of the National Autonomous University of Mexico (UNAM) in Mexico City:
Transgenes from genetically modified (GM) maize (corn) crops have been found in traditional ‘landrace’ maize in the Mexican heartland, a study says. The work largely confirms a similar, controversial result published in Nature in 2001 and may reignite the debate in Mexico over GM crops.
The paper reports finding transgenes in three of the 23 locations that were sampled in 2001, and again in two of those locations using samples taken in 2004.
In 1998, the Mexican government outlawed the planting of GM maize to protect its approximately 60 domesticated landraces and their wild relatives. But newspaper reports suggest that farmers have planted at least 70 hectares of GM maize crops in the northern state of Chihuahua, and it is unclear what repercussions this may have.
Only about 25% of the maize planted in Mexico comes from commercially sold seed; the majority is saved from harvest to harvest. That’s why, says Álvarez-Buylla, researchers need to pin down whether transgenes really have made it into local crops. “It is urgent to establish rigorous molecular and sampling criteria for biomonitoring at centres of crop origination and diversification,” the team writes. (Rex Dalton, Nature News)
The new paper examined thousands of seed and leaf samples, looking for the presence of two genes introduced into GM crops, a gene promoter from the 35S cauliflower mosaic virus, and the nopaline synthase terminator, NOSt. They found them in about 1 in 100 fields. These included fields sampled by Chapela and Quist in the 2001 paper. Snow, the author of the PNAS paper that didn’t confirm the Chapela findings, said she believes the new Nature paper is well done and significant for showing how easily the transgene have spread.
The controversy is far from over. The paper was submitted to PNAS but rejected as of insufficient interest, noting in addition the opinion of a reviewer that it could, according to the story in Nature, “gain undue exposure in the press due to a political or other environmental agenda.” That was a reviewer’s comment, not the editor’s view, but one wonders what role that notion played in the decision of PNAS not to publish this paper. It is interesting to observe that PNAS published the Snow paper with negative results, declined to publish the Álvarez-Buylla paper with positive results, while Nature published the Chapela paper in 2001, appeared to have gotten its fingers singed in the ensuing brouhaha, and is now running a news piece about a yet to be published paper in another journal that seems to confirm their earlier publication.
No pride or politics involved, though. That’s for sure. | <urn:uuid:8376e7e2-2163-4d61-bec6-e548358e58f0> | 3.46875 | 840 | Personal Blog | Science & Tech. | 30.392639 |
Hi, I have a question about genetics and evolution that I have been struggling to figure out i recent years.
All species adapt to survive, and they to that through mutation and evolution (very roughly) but my question is, what mechanism in the genes or body decides what mutation takes place on the body of the individual animal?
Recently I watched a documentary on Animal Planet about South America and the evolution of the animals there. Now take the giant ant eater. It has extra joints between it's vertebra to reinforce it's back when it's eating termites. Now how did the body figure out that extra joints in the back were the best solution to that problem? Also, the ant eaters jaws are "sealed" by the skin so it can't open it's mouth apart from the front where it's tounge gathers termites. Again, what mechanism decides what mutation is best for the animal, and how does the body itself figure out exactly what mutation is the best for it's survival?
Is it a question of trial and error? Of course I understand that almost every animal is constantly evolving to suit the enviroment it lives in, but I think it's an interesting question.
I hope my question makes sense.
Christopher Hower - Denmark. | <urn:uuid:7beb6b8c-8f08-48ff-9413-6aa56a6f7034> | 3.0625 | 259 | Q&A Forum | Science & Tech. | 52.866667 |
Thread subject: Diptera.info :: Pinning flies and wasps and some curious questions.
Posted by diphascon on 25-04-2007 20:51
another curious question... Why can't bacterias "eat" wasps' (flies') exoskeleton??
in fact, there are "chitinovorous bacteria" as well as chitin degrading fungi. So why do fungi bother the collecting entomologist more than bacteria? A few speculations:
First of all, I think there isn't only chitin but also a lot of all the rest available on a dead dried insect (protein, fat etc.). OK, that's not an answer ...
Second, as far as I know, some fungi are much better than bacteria when it comes to extracting water (which all living beings need) from almost dry substrates (see e.g. the mould on your jam. Many bacteria would like the sugar as well but cannot get water out of the highly osmotic stuff).
Third, if there would be a tiny little bit of bacterial growth on your pinned flies (maybe there actually is, and more is not to be expected) it would probably be hard to detect that at all for the non-microbiologist. Fungi grow in conspicious filaments that are easily seen but bacteria form plaques on dry surfaces that are usually tiny and invisible under "natural" conditions.
cheers - martin | <urn:uuid:179c3fff-c328-4153-ae91-25ef1c5ef742> | 2.703125 | 298 | Comment Section | Science & Tech. | 64.160461 |
FORGET little green men, SETI - the search for extraterrestrial intelligence - should seek signals from sentient machines, says Seth Shostak of the SETI Institute in Mountain View, California.
He argues that intelligent aliens would probably develop artificial intelligence (AI). These sentient machines will be more prolific and longer-lived than their biological creators and so easier to detect. "The aliens - at least, any we hear - will be machines," he writes in Acta Astronautica (DOI: 10.1016/j.actaastro.2010.06.028).
Instead of focusing on habitable worlds, SETI should look for places that artificial intelligences are likely to haunt, Shostak adds.
"Provided they don't destroy themselves and don't hide, and communicate with long-range, comprehensible signals, they are the likely ones we will observe," agrees AI researcher Marcus Hutter of the Australian National University in Canberra.
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:9811d792-ed9a-48b1-aaae-4c673cf5156c> | 2.953125 | 221 | Truncated | Science & Tech. | 39.387114 |
|Apr13-08, 03:19 PM||#1|
could someone please explain in simple terms what ampere-turns and ampere turns per meter means?
|Apr14-08, 08:42 AM||#2|
It has been found that an electric current sets up a magnetic field
similar to that produced by a permanent magnet. This action is known as
Electromagnetism and is very important in many devices. A desirable
feature of electromagnetism is that it is possible to control the strength
and polarity of the magnetic field. When current exists in a coil, the coil
has all the magnetic qualities of a permanent magnet and is called an
Electromagnet. If this electromagnet is brought near a permanent
magnet or another electromagnet, the like and unlike poles react exactly
as explained for the permanent magnets. Moreover, an increase of current
in the coil increases the strength of the magnetic field, and a decrease
of current weakens the field.
When the number of loops or turns of the coil is increased and the
current remains the same, the strength of the magnetic field increases.
Each loop or turn of the coil sets up it's own magnetic field, which unites
with the fields of the other loops to produce the field around the entire
coil. The more loops, the more magnetic fields unite and reinforce each other
and, as a result, the total magnetic field becomes stronger.
To compare the magnetic strength of different coils, and to obtain
a basis for measuring the magnetomotive force of an electromagnet, the number
of turns of wire is multiplied by the number of amperes of current carried
by the wire and the result is called Ampere-Turns (NI). The ampere-turn
is the unit for measuring the magnetomotive force of a current-carrying
coil. In a formula, the magnetomotive force in ampere-turns can be expressed
F = NI
F = magnetomotive force in ampere-turns
N = number of turns
I = current in amperes
A coil with 10 turns and a current of 10 amperes has an F of 100
The above excerpted from: http://ourworld.compuserve.com/homepages/boyce_smith/magnets.htm
Ampere-turns per meter is just as it reads, the number of ampere turns per length of the electromagnetic coil.
|Apr15-08, 12:30 AM||#3|
thanks chris, that explained it very clearly
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Stoichiometry: Real World Reactions
Summary (or Welcome to the Real World)
We don't live in an ideal world. Humans aren't able to measure exact quantities of substances; not even specially designed machines are completely reliable. In any reaction, there will always be one reactant that you should have added more of. However, even if you were a superhuman and could measure perfectly, you still would be unsure of the results of your reaction.
Chemical reactions never completely consume reactants. You will always only get a percentage of the product you think you will. Chemical reactions are not just equations that you write down on paper; they are living works of nature that produce heat and energy. | <urn:uuid:26d777a0-b457-4f2e-ac45-ac7e82418b35> | 3.375 | 143 | Knowledge Article | Science & Tech. | 42.750424 |
Well, since we did medicine last week I thought we’d move to a subject that’s near and dear to my heart: space research. One of the things I love about my field is that it literally changes every day. What we believe today may definitely NOT be what we believe next week. And one of the biggest fields that’s changing every day is planetary science. That’s because we still have several intrepid robot explorers that are giving us daily reports about the conditions on Mars and Saturn.
The robot Cassini is in orbit around Saturn and we’ve learned more about Saturn and its many moons in the last four years than we learned in the previous 400. We’ve found new moons, seen a half-black, half-white moon (Iapetus) up close and learned that it has a 12-mile high mountain ridge around its equator. But one of the major objectives of the Cassini spacecraft was to explore Titan, the second largest moon in the solar system (after Jupiter’s Ganymede) and the only moon to have a substantial atmosphere.
NOT LIKE EARTH!
Cassini landed a probe on the surface of Titan. The surface had always been a mystery until Cassini because the atmosphere is opaque and we can’t see the surface from Earth.
The probe took many pictures in its spiral down to the surface and saw a landscape that was surprisingly Earth-like. There were mountains, cliffs and what appeared to be rivers flowing to large flat areas that looked suspiciously like large lakes or seas. But even though the surface looks like Earth, we knew it couldn’t be, because the average temperature on Titan is -290 degrees!
Interestingly enough, at those temperatures, water ice, as we know it, doesn’t exist. The only reason we have life here on Earth is that, unlike virtually any other compound, our kind of water ice floats on liquid water. If that weren’t true, the oceans would have frozen solid from the bottom up and we wouldn’t be here.
But at -290 degrees frozen water isn’t ice as we know it. Ice at the temperatures on Titan is water rocks; just like the familiar rocks here on Earth, but made of water. These water rocks would NOT float on liquid water (if there were any on Titan) they would sink like, well, a rock.
We are still studying the surface of Titan with radar and we’re discovering that the surface changes. Although scientists are still debating this, it appears there are volcanoes on Titan. They’re called cryovolcanos, which basically means ‘volcanoes’ much colder than you ever dreamed possible. And if the rocks that make them are made of water what are these volcanoes erupting? That’s right! Molten water!! Lava that is, in fact, water. They are probably also erupting liquid methane and ammonia. Certainly NOT Earth-like at all.
Is there life on Titan? We still don’t know, but we need to give up on the idea that life must be as we know it. The aliens will NOT be humans wearing monster costumes or sporting strange hairstyles.
A moon that erupts molten water. Strange indeed!
And now we’ll take a little trip from Saturn to Jupiter to have a look at the second biggest storm in the solar system and find out why it’s blushing.
A recent study has given new insights into why Oval BA, a giant anticyclone on Jupiter also known as Little Red, suddenly turned from white to red in a period of just a few months.
We all know about Jupiter’s Great Red Spot, a huge spinning storm that can be three times larger than Earth and has been on Jupiter’s surface for over 300 years.
A couple of years ago, I reported that a huge white spot had formed on Jupiter from a chain of white spot collisions that started way back in 1998. The large white spot that resulted was called Oval BA. Amateur astronomers reported a couple of years ago that Oval BA was beginning to turn red, but it wasn’t until April of last year that professional astronomers were able to image the impressive alteration of the second largest storm in the Solar System after the Great Red Spot (GRS).
The scientists that studied Little Red made an in-depth analysis of all the aspects regarding its history and evolution. The reddest color was concentrated in a ring around the spot’s center. But when the researchers calibrated images taken with the Hubble Space Telescope, they found out that Little Red didn’t actually change in red or infrared wavelengths. Instead, it became darker in blue and ultraviolet wavelengths, which made it look redder.
And the researchers didn’t limit themselves to data from Hubble. They also used images taken by the Cassini spacecraft on its way to Saturn as well as pictures taken by the New Horizons mission and computer models. They searched for possible causes for the color change, including alterations to dynamic, photochemical and diffusion processes.
Their conclusions? The most likely cause appears to be an upward and inward diffusion of either a colored compound or a coating vapor that may interact later with high energy solar photons at the upper levels of Little Red.
When they compared Little Red to The Great Red Spot, they found that the GRS is still redder than Little Red, most likely because it’s higher in Jupiter’s atmosphere, thicker and contains a higher concentration of the mysterious unknown chemical agents that give Jupiter its brownish-red color.
The scientists were able to rule out that the reddening was caused by any dynamic processes. They found no change to the strength of the “hurricane” and, although some changes in the circulation around the spot had taken place, the maximum wind speeds (which may range up to 250 mph or more!) were consistent with measurements previous to 2000 of Little Red or its white predecessors.
Their models also showed that the color change wasn’t caused by interactions of Little Red with the GRS, even though they were relatively close at the time. The flow around both vortices is so strong that it keeps the storms separate. They also ruled out the height of Little Red since it didn’t change; but there were large changes in the temperature gradient of the storm.
Bottom line? We STILL don’t know what causes the color, but we’ve ruled out several things that don’t. And that’s how science progress, you know. Ruling out one thing at a time that doesn’t fit what we actually observe. A slow process sometimes, but it works.
NOT ALWAYS ON THE LEVEL
One of the abiding ‘facts’ about our solar system is that virtually everything spins around the Sun on the same ‘table’. That ‘table’ is called the plane of the ecliptic and one of the things that made Pluto so unplanet-like is that its orbit is significantly inclined to the ecliptic plane. It doesn’t roll around on the same table as the planets.
Virtually the only things that humans routinely observe that don’t follow the ecliptic are the comets and an international team of scientists has found an unusual object whose backward and tilted orbit around the Sun may clarify the origins of certain comets.
In the first discovery of its kind, researchers from Canada, France and the United States have discovered an object that orbits around the Sun backwards, and tilted at an angle of 104 degrees – almost perpendicular to the orbits of the planets. This goes far toward proving that the comets exist in a large spherical cloud far beyond Neptune called the Oort Cloud.
The object is called 2008 KV42 and is made of icy rock. It’s also called a "trans-Neptunian" object since its orbital path is larger than that of Neptune. The object is roughly 30 miles across and about 3.5 billion miles from Earth.
We don’t normally look up or down in our solar system examination but the international research team has been carrying out a targeted search for objects with highly tilted orbits. Their discovery was made using the Canada-France-Hawaii Telescope in Hawaii, with fol
low-up observations provided by the MMT telescope in Arizona, the Cerro Tololo Inter-American Observatory (CTIO) four-metre telescope in Chile, and the Gemini South telescope, also in Chile.
The researchers had to use telescopes in both the northern and the southern hemispheres because 2008 KV42 would have been lost to view without the rapid tracking from the large telescopes in both hemispheres.
The discovery team is currently performing follow-up observations of 2008 KV42 to pin down its orbit with greater precision. They will then begin unraveling the archaeological information trapped in the orbit of this highly exceptional member of the trans-Neptunian population.
A near edge-on view of the solar ecliptic plane viewed from about 10 billion miles. This figure shows the orbits of Neptune (diameter 3 billion miles), Pluto, 2008 KV42 and 4 other ‘classical’ KBOs. Demonstrates the inclined nature of 2008 KV42’s orbit, when compared to other objects in the outer solar system. (Credit: Canada-France Ecliptic Plane Survey)
Volcanoes that erupt molten water, big red spots and strange visitors on a different plane. The solar system is full of wonder.
Cruise on over to the Deep Website at www.thedeepradioshow.com to learn more about space and many other topics. Enjoy! | <urn:uuid:22f8c15c-6179-4b15-8de5-804839fd8d42> | 3.140625 | 2,026 | Personal Blog | Science & Tech. | 53.198085 |
Laser beams can be made to form bright and dark intensity helices of light. Such helices have a pitch length on the order of a wavelength and may have applications in lithography and the manipulation of particles through optical forces. The formation of bright helices is more strongly constrained by optical resolution limits than that of dark helices, corresponding scaling laws are derived and ...
Laser beams can be made to form dark as well as bright intensity helices, or corkscrews of light. In a paper shortly to appear in Optics Express, Dr Ole Steuernagel, at the University of Hertfordshire's Science and Technology Research Institute, has now shown that forming dark helices can have considerable advantages over employing their commonly considered bright cousins.
Dark helices are shaped like their bright helix counterparts but they are helically-shaped threads of darkness embedded in a background of bright light. And unlike bright helices, dark helices are not resolution limited and provide a better intensity contrast than bright ones. In addition, they can be generated one-by-one but, more importantly, they can also be arranged in a massively parallel fashion on a tight grid.
The dark helices could be most beneficial in a quantum-transport setting because their waveguides interact less with trapped particles than their bright counterparts. Because of this, dark helices are more suitable for sensitive quantum systems because they do less damage.
all matter within the double layer is basically the same, just some with a slightly higher charge than others.
errr, i thought that a double layer was defined by areas of different charges.....If we knew what "charge" was, it would be easier to understand.
Your suggestion that positive and negative are the same, but of different intensities would be somewhat valid if we defined these by comparison, but we do not. Each is an arbitrary designation and is defined by comparison to as neutral an environment as we can generate. They are not compared to one another. Detectors will react
the opposite to negative as they will to positive.
Michael V wrote:Plasmatic,
Don't understand what you're getting at with "deformable balls" (ooh, er, missus).
Regarding "nothingness", there may be some curious and esoteric philosophies that propose a reality where motion exists only as an illusion. However, I am unwilling to accept such fictitious oddities as real and instead I insist upon motion as real, whether you choose it to be absolute or relative.
"From acceptance of motion as real, there is no logical escape from that which must follow. To allow motion we must also embrace the concept of separation. These ideas are mutually proved and undeniable. With spatial separation comes two further concepts that are equally proved and equally undeniable: empty space and discrete “particles” of material substance. In short we have two classes of volume occupying entity. One is inert, that is empty space, the other is interactive, that is particles of material substance. The interactive material substance may be further split into two broad categories: one is the ponderable matter that are electrons and protons and that which their interaction form; the other is aethereal particles that are responsible for producing and mediating the interactions between electrons and protons. With motion included, all theories and models must comply with the concept of particles separated by completely empty space. There is no philosophical or logical avoidance to this regime, as without the reality of motion, all other considerations become meaningless and invalid."
Whether from this we can say that "nothingness" is an "existent" or whether it might be more accurate to say that it is "a lack of existent", is basically only a semantic argument. However, what is absolutely CERTAIN is that most of the universe is absolutely completely unoccupied empty space devoid of any matter or aethereal substance whatsoever.
If are able to define a worthwhile counter-argument I would be very pleased to read it.
most of the universe is absolutely completely unoccupied empty space devoid of any matter or aethereal substance whatsoever.
Plasmatic wrote:.....a fluid sea of permeable existents.....
Plasmatic wrote:Nothing is the concept that refers to the absence of an entity in a given context where necessarily other entities are present.
If anything, "Nothing is the concept" that defines Something. As for other entities being "necessarily" present, there is no necessity in any way. The simple acceptance of multiple entities and boundaries, is in itself further demonstration of the "necessity" of separation.
This is exactly defined as particles separated by empty space. I understand the appeal of visualising a continuous aethereal fluid, but it is a vital necessity of a fluid of any description that it be particles separated by empty space. An atomic fluid is 99.9999....% empty space, an aethereal fluid will be no different.
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An adult reed warbler feeds a common cuckoo chick,
not recognizing the baby bird as a parasite
In the world of birds, cuckoos are pretty unpopular. Maybe it’s something about how they lay their eggs in others’ nests so that their chicks will steal food and attention from the natural-born chicks. This can kick off an evolutionary arms race that researchers are already familiar with: the cuckoo eggs evolve to look more and more like the host eggs, and the hosts evolve to get better and better at recognizing the foreign eggs.
Now researchers have discovered another cuckoo-versus-host evolutionary race running in parallel—and it has led to the evolution of two different forms of the same species of female cuckoo. | <urn:uuid:999b5fae-5f4d-4838-99df-996fba84f931> | 2.9375 | 157 | Truncated | Science & Tech. | 35.69545 |
December 15, 2008
These whispering bats never really whispered. Their echolocations were thought to be about 70 decibels, about the level of sound coming from regular speaking. But when two scientists measured the calls from a couple of species—the Jamaican fruit bat (Artibeus jamaicensis) and the long-legged bat (Macrophyllum macrophyllym)—in Panama, they were a bit surprised to find out how inappropriate the name really was.
They report in the Journal of Experimental Biology that the long-legged bat reached a top volume of 105 decibels (louder than the subway in New York) and the Jamaican fruit bat topped out at 110 decibels (front row of a rock concert). Because the decibel scale is logarithmic, that means the fruit bat was about twice as loud is its long-legged cousin.
The scientists attribute the difference in noise level to the difference in lifestyle. The Jamaican fruit bat has to search over a large area to find fruiting trees. Loud, long-carrying shrieks would help the bat orient itself in its forest home. (Bats use echolocation for finding their way and finding their prey.) The long-legged bat, though, scoops up insects from the water with its tail, and may not require such a wide-ranging call.
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Question on Photochemical Chlorination
A saturated hydrocarbon (A) burns in oxygen to give carbon dioxide and water. Approximately twice as much CO2 as H2O (by weight) is produced by this combustion, the actual factor being 2.03. Photochemical chlorination of the (A) by 2.0 equivalents of chlorine gives a mixture of mono-, di- and trichloro compounds, along with small amounts of higher chlorination products. Only one monochloro isomer is formed, but there are two dichloro isomers and three trichloro isomers produced in the reaction. What is the name of (A)? | <urn:uuid:04dca4bd-dbc9-4df6-b687-e5546a23fefb> | 3.203125 | 135 | Q&A Forum | Science & Tech. | 37.455385 |
exlegelibertas asked: I read another article this morning about hive disruption syndrome and about bee-dieoffs in general. The article framed the issue in a wider context of a 'sixth extinction.' As a layman I'm generally sold on these theories, despite their grim outlook. Assuming (as I do) that they're probably the result of anthropogenic climate change, what do you think the proper adaptation methods will be, considering the necessity of honeybees in pollinating most crops around the world?
Great question and I did a little research for you (learned a lot, so thanks!).
The so-called “sixth extinction” theory has been around for a while. I’d avoid reading about it, since it’s all doom. Still, adaptation strategies for bees and other pollinators are only now being taken seriously.
Keep in mind that environmentalism is ‘stewardship’ - it requires long-term thinking, far beyond your life-time. Solutions take time and decades of research and testing. So, managing impacts are part of a long transition…
Most adaptation strategies and responses are part of bigger plans that deal with ecosystems and agriculture, so they’re more likely to be a chapter in larger documents. Here a few resources:
NASA (yes, NASA) has HoneyBeeNet, a project on climate change impacts on honeybees and ag. Excellent overview of the issue, but short on strategies. Well worth a skim (and fun to see the connection between NASA science, climate, and bees!).
This list of 30 issues that the independent Govt Accountability Office (GAO) analyzed is mind-boggling. The U.S. Federal Government, says the GAO, is embarrassingly underprepared to deal with the volume and increasing frequency of climate related disasters, such as Hurricane Sandy, droughts in the southwest, super tornadoes in Oklahoma, etc. They conclude(!) that funding for disaster response and post-disaster planning is completely inadequate and in need of an overhaul.
(The satellite) systems are critical to weather forecasters, climatologists, and the military to map and monitor changes in weather, climate, the oceans, and the environment.
Federal agencies are currently planning and executing major satellite acquisition programs to replace existing polar and geostationary satellite systems that are nearing the end of their expected life spans. However, these programs have troubled legacies of cost increases, missed milestones, technical problems, and management challenges that have resulted in reduced functionality and slips to planned launch dates. As a result, the continuity of satellite data is at risk.
The GAO’s High Risk Report is absolutely worth clicking through. Each of the 30 items are categorized and easy to read. The two above on climate and satellites also include video summaries.
If you are wandering around Greenland’s ice sheet and you run into this crazy thing, it is NASA’s GROVER (government acronym for something Goddard Remotely Operated Vehicle for Exploration and Research). It is solar powered and it crawls around Greenland on its own and uses ground-penetrating radar to look at ice. And it’s cool.
NASA robot explores ice in Greenland. Video. Will explore for months at a time via remote. Possibly prototype to explore other planets.
The fire maps show the locations of actively burning fires around the world on a monthly basis, based on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. The colors are based on a count of the number (not size) of fires observed within a 1,000-square-kilometer area. White pixels show the high end of the count —as many as 100 fires in a 1,000-square-kilometer area per day. Yellow pixels show as many as 10 fires, orange shows as many as 5 fires, and red areas as few as 1 fire per day. Via EO NASA
Cruise over glaciers in Greenland. Researchers use aerial footage for data collection and monitoring.
Few of us ever get to see Greenland’s glaciers from 500 meters above the ice. But in this video — recorded on April 9,2013 in southeast Greenland using a cockpit camera installed and operated by the National Suborbital Education and Research Center, or NSERC — we see what Operation IceBridge’s pilots see as they fly NASA’s P-3B airborne laboratory low over the Arctic.
Following a glacier’s sometimes winding flow line gives IceBridge researchers a perspective on the ice not possible from satellites which pass in straight lines overhead. By gathering such data, IceBridge is helping to build a continuous record of change in the polar regions.
temperature and vegetation growth at northern latitudes now resemble those found 4 degrees to 6 degrees of latitude farther south as recently as 1982.
“Higher northern latitudes are getting warmer, Arctic sea ice and the duration of snow cover are diminishing, the growing season is getting longer and plants are growing more,” said Ranga Myneni of Boston University’s Department of Earth and Environment. “In the north’s Arctic and boreal areas, the characteristics of the seasons are changing, leading to great disruptions for plants and related ecosystems.”
Image: Of the 10 million square miles (26 million square kilometers) of northern vegetated lands, 34 to 41 percent showed increases in plant growth (green and blue), 3 to 5 percent showed decreases in plant growth (orange and red), and 51 to 62 percent showed no changes (yellow) over the past 30 years. Satellite data in this visualization are from the AVHRR and MODIS instruments, which contribute to a vegetation index that allows researchers to track changes in plant growth over large areas.
Soon, governments and citizens alike will be able to spot illegal loggers from space. A new tool called Global Forest Watch 2.0 will give anyone with a computer or smartphone the ability to zoom in on forests around the world and spy on illegal cutting operations in near-real time.
“Global Forest Watch 2.0 aims to transform access to information about what’s happening to forests everywhere around the globe,” says Nigel Sizer, the director of the World Resources Institute’s Global Forest Initiative in Washington, D.C. “The platform allows people to see those numbers—how much clearing is done year by year in oil concessions in Indonesia, for example, or by a cattle ranch in the Brazilian Amazon—without involving training in technology or science.”
The open-access online monitoring platform, which will include two major data sets when it launches in the first half of 2013, combines satellite technology, data sharing and social networks to combat deforestation.
The first dataset, provided by the NASA MODIS system, is updated every 16 days. Over that same period, algorithms compute the likelihood that any given 250-square-meter patch of forest has been cleared based upon the remote-sensing imagery. Higher spatial resolution data, provided by the University of Maryland, will be added annually. The platform relies upon cloud computing for storing the massive datasets involved in visualizing and processing the maps.
NASA and the Department of the Interior’s U.S. Geological Survey (USGS) have released the first images from the Landsat Data Continuity Mission (LDCM) satellite, which was launched Feb. 11.
The natural-color images show the intersection of the United States Great Plains and the Front Range of the Rocky Mountains in Wyoming and Colorado. In the images, green coniferous forests in the mountains stretch down to the brown plains with Denver and other cities strung south to north.
LDCM acquired the images at about 1:40 p.m. EDT March 18. The satellite’s Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments observed the scene simultaneously. The USGS Earth Resources Observation and Science Center in Sioux Falls, S.D., processed the data.
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Date: October 11, 2001
Creator: Schmidt, Laurie J.
Description: This feature article provides a summary of study about the role of clouds in the balance. Until recently, scientists were uncertain whether clouds had an overall net cooling or heating effect on the Earth's climate. But recent studies show that, in the tropics, a "near cancellation" between shortwave cooling and longwave warming exists, which indicates that the amount of incoming radiant energy is roughly equal to the amount of outgoing radiation. However, small changes in tropical cloudiness can disrupt this precarious balance.
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OBSERVATORY . Up to a comparatively
See also:recent date an " observatory " was a place exclusively devoted to the taking of astronomical observations, although frequently a rough account of the
See also:weather was kept . When the progress of terrestrial magnetism and meteorology began to make
See also:regular observations necessary, the
See also:duty of taking these was often thrown on astronomical observatories, although in some cases
See also:separate institutions were created for the purpose . In this article the astronomical observatories will be chiefly considered . Up to about 300 B.C. it can scarcely be said that an observatory existed anywhere, as the crude observations of the heavens then taken were only made by individuals and at intervals, employing the simplest possible apparatus . Thus, according to
See also:Strabo .
See also:Eudoxus had an observatory at
See also:Cnidus . But, when philo-. ophical
See also:speculation had exhausted its resources, and an accumulation of facts was found to be necessary before the knowledge of the construction of the universe could advance farther, the first observatory was founded at Alexandria, and continued in activity for about four
See also:hundred years, or until the
See also:middle or end of the and century of the Christian era .
See also:Hipparchus of Rhodes, the founder of
See also:modern astronomy, by repeating observations made at Alexandria, discovered the precession of the equinoxes, and investigated with considerable success the motions of the
See also:moon and
See also:planets . His
See also:work was continued by more or less distinguished astronomers, until
See also:Ptolemy (in the and century A.D.) gave the astronomy of Alexandria its final development . When science again began to be cultivated after the dark ages which followed, we find several observatories founded by Arabian princes; first one at
See also:Damascus, next one at
See also:Bagdad built by the
See also:caliph Al-
See also:Mamun early in the 9th century, then one on the Mokattam near Cairo, built for
See also:Ibn Yunis by the caliph Iiakim (about
See also:I000 A.D.), where the IJakimite tables of the sun, moon and planets were constructed . The Mongol khans followed the example; thus arose the splendid observatory at
See also:Maragha in the
See also:north-west of
See also:Persia, founded about A.D .
1260 by HulaguKhan, where Nasir Uddin constructed the Ilohkhanic tables; and in the 15th century the observatory at
See also:Samarkand was founded by Ulugh Beg, and served not only in the construction of new planetary tables but also in the formation of a new
See also:catalogue of stars . With the commencement of scientific studies in
See also:Europe in the 15th century the
See also:necessity of astronomical observations became at once
See also:felt, as they afforded the only hope of improving the theory of the motions of the
See also:celestial bodies . Although astronomy was taught in all
See also:universities, the taking of observations was for two hundred years
See also:left to private individuals . The first observatory in Europe was erected at
See also:Nuremberg in 1472 by a wealthy
See also:citizen, Bernhard
See also:Walther, who for some years enjoyed the co-operation of the celebrated astronomer
See also:Regiomontanus . At this observatory, where the work was continued till the founder's
See also:death in 1504, many new methods of observing were invented, so that the revival of
See also:practical astronomy may be dated from its foundation . The two celebrated observatories of the 16th century, Tycho Brahe's on the Danish
See also:island of Hven (in activity from 1576 to 1597) and that of Landgrave
See also:William IV. at Cassel (1561-1597), made a
See also:complete revolution in the
See also:art of observing . Tycho Brahe may claim the
See also:honour of having been the first to see the necessity of carrying on for a number of years an extensive and carefully-planned series of observations with various
See also:instruments, worked by himself and a
See also:staff of assistants . In this respect his observatory (Uraniburgum) resembles our modern larger institutions
See also:mare closely than do many observatories of much more recent date . The mighty impulse which Tycho Brahe gave to practical astronomy at last installed this science at the universities, among which those of
See also:Leiden and
See also:Copenhagen were the first to found observatories . We still find a large private observatory in the middle of the 17th century, that of Johannes Hevehus at
See also:Danzig, but the foundation of the royal observatories at
See also:Paris and
See also:Greenwich and of numerous university observatories shows how rapidly the importance of observations had become recognized by governments and public bodies, and it is not until within the last hundred and
See also:thirty years that the development of various new branches of astronomy has enabled private observers to compete with public institutions . The instruments employed in observatories have of course changed considerably during the last two hundred years . When the first royal observatories were founded, the
See also:principal instruments were the mural quadrant for measuring meridian
See also:zenith distances of stars, and the
See also:sextant for measuring distances of stars inter se, with a view of determining their difference of right ascension by a
See also:simple calculation .
These instruments were introduced by Tycho Brahe, but were subsequently much improved by the addition of telescopes and micrometers . When the
See also:law of gravitation was discovered it became necessary totest the correctness of the theoretical conclusions
See also:drawn from it as to the motions within the solar
See also:system, and this necessarily added to the importance of observations . By degrees, as theory progressed, it made greater demands for the accuracy of observations, and accordingly the instruments had to be improved . The transit instrument superseded the sextant and offered the
See also:advantage of furnishing the difference of right ascension directly; the clocks and chronometers were greatly improved; and lastly astronomers began early in the loth century to treat their instruments, not as faultless apparatuses but as imperfect ones, whose errors of construction had to be detected, studied and taken into account before the results of observations could be used to test the theory . That century also witnessed the combination of the transit instrument and the mural quadrant or circle in one instrument—the transit or meridian circle . While the necessity of following the sun, moon and planets as regularly as possible increased the daily work of observatories, other branches of astronomy were opened and demanded other observations . Hitherto observations of the " fixed stars " had been supposed to be of little importance beyond fixing points of comparison for observations of the movable bodies . But when many of the fixed stars were found to be endowed with " proper motion," it became necessary to include them among the
See also:objects of
See also:attention, and in their turn the hitherto totally neglected telescopic stars had to be observed with precision, when they were required as comparison stars for comets or minor planets . Thus the
See also:field of work for meridian instruments became very considerably enlarged . In addition to this, the increase of
See also:optical power of telescopes revealed hitherto unknown objects—double stars and nebulae—and brought the study of the
See also:physical constitution of the heavenly bodies within the range of observatory work . Researches connected with these matters were, however, for a number of years chiefly left to
See also:amateur observers, and it is only since about 183o that many public observatories have taken up this kind of work . The application of spectrum analysis, photometry, &c., in astronomy has still more increased the number and variety of observations to be made, while the use of photography in work of precision has completely revolutionized many branches of practical astronomy .
It has now become necessary for most observatories to devote themselves to one or two
See also:fields of work . It would be difficult to arrange the existing observatories into classes either according to the work pursued in them or their organization, as the work in many cases at different times has been directed to different objects, while the organization depends mostly on
See also:national and
See also:local circumstances . As already alluded to above, one of the principal characteristics of the larger observatories of the
See also:day is the distribution of the work among a number of assistants under the general superintendence of a director . This applies principally to the
See also:great observatories, where the sun, moon, planets and a limited number of fixed stars are without interruption being observed, but even among these institutions hardly two are conducted on the same principles . Thus in Greenwich the instruments and observations are all treated according to strict rules laid down by the astronomer-royal, while in
See also:Washington or Pulkowa each astronomer has to a certain extent his choice as to the treatment of the instrument and arrangement of the observations . The same is the case with the smaller institutions, in most of which these arrangements vary very much with
See also:change of personnel . The way in which the results of observations are published depends principally on the
See also:size of the institutions . The larger observatories issue their "
See also:annals " or " observations " as separate periodically-published volumes, while the smaller ones chiefly depend on scientific
See also:journals to
See also:lay their results before the public, naturally less fully as to details . Subjoined is a catalogue of public and private observatories still in activity in 1910 or in existence within the past hundred years . (4f°= 1° of long.) (Abbreviations: ap., aperture; equat.,
See also:equatorial; obs., observatory or observations; o.g.,
See also:glass; phot., photographic; refl., reflector; refr., refractor; s.g., silvered glass; vis., visual; univ., university .
OBSEQUIES (Med. Lat. obsequiae, formed after class....
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Thursday, June 25, 2009 - 15:56 in Earth & Climate
Carbon dioxide being absorbed by the oceans is having a puzzling effect on fish — their ears get bigger. Scientists say the phenomenon could create unexpected effects as seas become more acidic.
- Cranking up the volumeMon, 29 Sep 2008, 15:14:52 EDT
- Ocean growing more acidic faster than once thoughtMon, 24 Nov 2008, 14:08:06 EST
- Broadcast study of ocean acidification to date helps scientists evaluate effects on marine lifeMon, 23 Jan 2012, 21:33:04 EST
- Oceans absorbing carbon dioxide more slowly, Yale scientist findsTue, 24 Nov 2009, 13:56:45 EST
- Carbon emissions threaten fish populationsWed, 7 Jul 2010, 9:37:02 EDT | <urn:uuid:4be17ae7-f3dd-4fdd-bd51-f00cde0c459b> | 2.71875 | 164 | Content Listing | Science & Tech. | 28.561196 |
The ocean is so big … how could this be happening? Why didn’t the gigantic Pacific Ocean better dilute Fukushima radiation?
A 1955 U.S. government report concluded that the ocean may not adequately dilute radiation from nuclear accidents.
MIT says that seawater which is itself radioactive may begin hitting the West Coast within 5 years.
In 10 years, peak radioactive cesium levels off of the West Coast of North America could be 10 times higher than at the coast of Japan.
As we’ve previously noted, Reuters reports that Alaskan seals are suffering mysterious lesions and hair loss:
Scientists in Alaska are investigating whether local seals are being sickened by radiation from Japan’s crippled Fukushima nuclear plant.
Scores of ring seals have washed up on Alaska’s Arctic coastline since July, suffering or killed by a mysterious disease marked by bleeding lesions on the hind flippers, irritated skin around the nose and eyes and patchy hair loss on the animals’ fur coats.
“We recently received samples of seal tissue from diseased animals captured near St. Lawrence Island with a request to examine the material for radioactivity,” said John Kelley, Professor Emeritus at the Institute of Marine Science at the University of Alaska Fairbanks.
“There is concern expressed by some members of the local communities that there may be some relationship to the Fukushima nuclear reactor’s damage,” he said.
We reported yesterday that a new scientific paper shows that the Fukushima radioactive plume contaminated the entire Northern hemisphere during a relatively short period of time, and Ene News today reports on a potential correlation:
Continue reading at Fukushima Radiation: Japan Irradiates the West Coast of North America
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Deep Impact was the first mission to eject material from a comet's surface.
It is a coincidence that Deep Impact shares its name with a 1998 science fiction disaster film about a comet.
Author Arthur C. Clarke suggested the idea of impacting a comet in his novel 2001: A Space Odyssey
Deep Impact's small probe was the first manmade object to collide with a comet (right).
EPOXI has double meaning. EPO stands for EPOCh the Extrasolar Planet Observation and Characterization phase of mission. XI is short for the spacecraft's extended investigation of comets.
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Thursday, February 09, 2012
How the Zebra got his stripes
How the Zebra came to have stripes has eluded scientists for all time, up until now apparently. It seems that the African blood-sucking flies that carry blood-borne illnesses among other things, are attracted to reflected sun light that is polarized in a plane that is parallel to the ground. It turns out that most warm-blooded animals have coats that reflect light this way. The Zebra's vertical stripes, however, reflect sun light polarized in a vertical plane and the flies don't like it.
In conversations with my son about why living things are the way they are, I've always told him to apply the caveman/saber-toothed tiger example to the question....or in this case the zebra/blood-sucking fly example. That is, if a genetic mutation helps the caveman not get eaten by the tiger, then it will remain in the genes of that civilization until everybody benefits from it.
Every physical characteristic every living thing has can be explained by thinking about how it makes life easier on a dangerous planet, with predators, temperature and light fluctuations, and gravity. | <urn:uuid:fc478539-a391-42ff-84fe-7648acb6499a> | 3.28125 | 240 | Personal Blog | Science & Tech. | 49.947628 |
Learning from hot Jupiters
December 15, 2010By studying how massive planets may have formed, MIT astrophysicist sets the stage for studying smaller, more Earthlike planets.
Building a list of Earth candidates
December 14, 2010MIT researchers increase their odds of detecting an Earthlike planet by working on a combination of satellite missions.
Explained: the Doppler effect
August 3, 2010The same phenomenon behind changes in the pitch of a moving ambulance’s siren is helping astronomers locate and study distant planets.
In the search for Earthlike exoplanets, GJ 436b has much to tell us
April 22, 2010First detailed analysis of the atmosphere of a Neptune-sized planet reveals surprisingly low methane levels, presents "new territory" for researching planets outside our solar system
Oddball stars explained
September 17, 2009New observations solve longstanding mystery of tipped rotation. In addition to shedding light on how binary stars form, the explanation knocks down a possible challenge to Einstein's theory of relativity.
The hunt for dark matter
September 17, 2009MIT physicists are working on new detectors that may, at last, help them find the elusive particles thought to constitute up to a quarter of the universe. | <urn:uuid:189ce36e-6b5f-43d4-9559-e5ca8433c8a1> | 3.1875 | 250 | Content Listing | Science & Tech. | 22.858596 |
Beth Kaplin, PhD
Department of Environmental Studies
I investigated the role of white-faced capuchin monkeys (Cebus capucinus) in processes of seed dispersal within a tropica premontane wet forest and its surrounding matrix in Monteverde, Costa Rica. No study prior to this had examined capuchins in a tropical premontane wet forest. In this study C. capucinus ate a diverse variety of fruit (45 species) and passed intact seeds of 33 species, some of which were viable. Psidium guajava, and introduced species, was a significant component of the capuchin’s diet during this study. The consumption of this fruit species resulted in a significant decline in overall seed species diversity and abundance in C. capunchin defecations and may be negatively affecting the dispersal of native forest species. An assessment of post dispersal seed fate is needed to determine the overall seed dispersal effectiveness of these primates in Monteverde. To explore how my research fits in with the literature on primate seed dispersal I conducted a literature review on the similarities of seed dispersal ecology of this New World primate species and a frugivorous Old World monkey, the red-tail monkey (Cercopithecus ascanius). I compared fruit handling behaviors, foraging patterns, food processing, gut retention time, and defecation patterns of the two species. Both species are described as effective seed dispersers based on the diverse variety of fruits they consume and the fact that they disperse viable seeds. | <urn:uuid:88ed33e7-6d6b-4334-9137-69f60cf6806b> | 3.28125 | 316 | Academic Writing | Science & Tech. | 22.790909 |
barani at mace.cc.purdue.edu
Thu Jun 29 15:33:03 EST 1995
>Article: 1782 of bionet.xtallography
>From: bmbtdf at leeds.ac.uk (T.D. Flint)
>Subject: Fourier Transforms
>Date: Thu, 29 Jun 1995 13:32:32 +0100 (BST)
>I just can not understand exactly what is going on in a Fourier transform. I
>know that amplitude and phase values are calculated etc and that you end up
>with the power spec. but i have asked SO MANY people what is going on and
>either they don't understand it themselves, or they do and can not explain it
>in such a way for me to understand. Can any body explain it or give me a
>reference that is understandable. I have read many but never quite seem to
Fourier Transform simply gives you the frequencies of various
harmonic waves that combine together and form the particular
signal. In Fourier Series this is the same as representing a
complicated function in terms of a sum of many simple sinusoidal
functions (each with different wavelength).
The best way to understand Fourier Transform is through
numerical methods that is well illustrated in a book
by M.M.Woolfson "An Introduction to X-ray Crystallography".
OR get hold of some book by R.N.Bracewell for signal processing
and Fourier transforms.
More information about the Xtal-log | <urn:uuid:fd35a9d5-9435-4320-9cf1-be1a31626fb4> | 3.09375 | 336 | Comment Section | Science & Tech. | 71.46019 |
They have four membranous wings, with few reticulations, and usually with a thickened, dark spot on the front edge of the anterior wings. In most of the species, the tongue, or lingua, is converted into an organ for sucking honey, or other liquid food, and the mandibles are adapted for biting or cutting. In one large division (Aculeata), including the bees, wasps, and ants, the females and workers usually have a sting, which is only a modified ovipositor.
Results from our forum
... and faded manifestation of "creative intelligence." This is the same social insects, provided such relics of two integers: public-Hymenoptera (wasps, bees, ants), which became public, according to various sources, from some point between 50 and 100 million years ago (an ancestor ...
See entire post | <urn:uuid:6920742b-7f5d-4411-8628-247ddc339e53> | 3.09375 | 179 | Truncated | Science & Tech. | 47.393319 |
Looking for Cramster? Cramster is now Chegg Homework Help. Learn More
electric field ?, last chance for glory!!
Two charges are placed on the x-axis. One
charge(q1 = +8.5 µC) is
atx1 = +3.0 cm and the
other(q2 = -11µC) is at x2
= +9.0 cm. At what spotalong the x-axis is the net
electric field zero?
Answered by Anonymous13 minutes later
with this problem you had to make sure that the force felt on
theequilibrium point which is in betwen the two charges from the
-11ucwas in a the negative direction. working everything out,
igot 0.026cm. try that answer
Answered by Anonymous16 hours later
The answer is as follows....since E 1 +
E2 = 0.......E 1 = -E
2 which must occur to left of q 1. | <urn:uuid:22ca7216-2883-4b50-a5bd-d9ba63079b47> | 2.796875 | 213 | Q&A Forum | Science & Tech. | 91.78 |
Color-Changing Process in Deciduos Leaves
As summer changes into autumn in the temperate zones, the long hot days change into shorter cooler days. During autumn, the decreasing amount of sunlight causes changes in deciduous plants, most noticeably in the color of their leaves. Most leaves are green because of the presence of chlorophyll, which is a green pigment (chemical that gives a substance color) needed for the food-making process called photosynthesis. Chlorophyll is produced in response to sunlight and warm temperatures. During the growing seasons of spring and summer, chlorophyll is continually being produced and broken down, and leaves appear green. In autumn, with less sunlight and cooler temperatures, chlorophyll production slows down and eventually stops. In time all the chlorophyll is destroyed.
As old chlorophyll breaks down, other pigments, which have always been present in the leaf but have been masked or hidden by the more abundant green chlorophyll, can now be seen. These pigments include xanthophyll, which produces yellow colors, and carotene, which produces yellow-orange colors. Xanthophyll and carotene do not break down as fast as chlorophyll does, so as the amount of chlorophyll decreases or disappears, these previously masked pigments are visible for a while. But eventually all of the pigments break down, and the leaves turn brown from the presence of tannin, a brown pigment. Most red pigment in autumn leaves is due to anthocyanin, a red plant pigment formed as a result of cool nighttime temperatures and bright sunny days.
As the daylight decreases, most deciduous plants start growing a layer of cells across the stem beneath the petiole of each leaf. This layer is called the abscission layer, and the leaves are actually "cut" from the stem by this layer of cells.
To determine the effect of sunlight on the color of leaves.
- deciduous tree or bush with large, dark
- green leaves
- 3-by-5-inch (7.5-by-12.5-cm) index card
- paper hole punch
- 4 paper clips
- transparent tape
- With adult approval, select 4 or more leaves of equal size on the plant that will be used in this experiment. The leaves should all receive equal amounts of sunlight and remain on the plant during the experiment.
- Fold the index card in half two times, placing the long sides together for each fold.
- Unfold the card and cut along each of the three folds, forming four strips.
- Fold one of the strips in half, placing the short ends together.
- Using the paper hole punch, punch two holes in the folded strip, cutting through both layers. Then slip this strip around one of the selected leaves. Secure the ends of the strip with a paper clip.
- Cover the holes in the paper strip on the top and underside of the leaf with transparent tape.
- Repeat steps 4 through 6, using the three remaining paper strips.
- Remove the paper strips after 7 or more days and observe the color of the leaves
In areas covered by the paper strip, the leaves change from dark green to pale green to yellow. The areas not covered by the strip, as well as those beneath the holes cut in the card, do not noticeably change color. | <urn:uuid:c0ac851c-9f66-4dcd-9337-2801e94add86> | 4 | 696 | Tutorial | Science & Tech. | 56.597636 |
When building packages there are several assumptions made within the instructions:
Several of the packages are patched before compilation, but only when the patch is needed to circumvent a problem. A patch is often needed in both this and the next chapter, but sometimes in only one or the other. Therefore, do not be concerned if instructions for a downloaded patch seem to be missing. Warning messages about offset or fuzz may also be encountered when applying a patch. Do not worry about these warnings, as the patch was still successfully applied.
During the compilation of most packages, there will be several warnings that scroll by on the screen. These are normal and can safely be ignored. These warnings are as they appear—warnings about deprecated, but not invalid, use of the C or C++ syntax. C standards change fairly often, and some packages still use the older standard. This is not a problem, but does prompt the warning.
Check one last time that the
environment variable is set up properly:
Make sure the output shows the path to the LFS partition's
mount point, which is
using our example.
Finally, two last important items must be emphasized:
The build instructions assume that the bash shell is in use.
To re-emphasize the build process:
Place all the sources and patches in a directory that
will be accessible from the chroot environment such as
not put sources
Change to the sources directory.
Using the tar program, extract the package to be built. In Chapter 5, ensure you are the lfs user when extracting the package.
Change to the directory created when the package was extracted.
Follow the book's instructions for building the package.
Change back to the sources directory.
Delete the extracted source directory and any
directories that were created in the build
process unless instructed otherwise. | <urn:uuid:34ccd428-12f4-4ecc-adda-99312be517a1> | 2.90625 | 375 | Tutorial | Software Dev. | 48.923524 |
• In the 12 August issue we stated that crinoids, or sea lilies, appeared 300 million years ago and pre-dated fish (p 49). Both have actually been around for a lot longer than that, coexisting in the Ordovician period between 490 and 443 million years ago, with the first fish possibly coming earlier than crinoids. Also, the subclass of crinoids with the ability to move appeared 200 million years ago, not a mere 200,000 years ago.
• Hone Harawira is a member of the New Zealand parliament for the Maori Party, not a "Maori minister" as we described him (19 August, p 12).
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:93c63c8d-13e9-4ecc-b645-6c05e44c4573> | 2.953125 | 166 | Truncated | Science & Tech. | 58.783598 |
(Lansing State Journal, Aug. 19, 1992)
Quantum physics deals with the smallest objects known. It is a set of theories that describe the interactions between objects such as electrons and protons, what makes up these objects and how they influence each other. It describes such things as how the atom works, how light is created and why some materials are superconducting and others are not. Two of its main principles:
For instance, there is a restrictions on the energy that a particle can have. An atom might have an energy of 1 unit or 2 units, it cannot have an energy of 2.5 units or anything else between 1 and 2. This is the origin of the word "quantum."
Beginning only 85 years ago, the study and development of quantum physics has led to many discoveries, among them are: | <urn:uuid:b1efaa7a-bc13-4f83-95df-f1026f5ac6f8> | 3.171875 | 171 | Knowledge Article | Science & Tech. | 59.151071 |
s people within the reach of El Niño know, the exchange of energy between the ocean and atmosphere can have effects that ripple across oceans and continents over periods of months and years. But sometimes the interplay of sea and sky gives birth to more violent, short-lived phenomena that play out over minutes to hours.
Warm water, combined with just the right conditions aloft in the atmosphere, can give rise to a spinning column of air -- a vortex. Tornadoes bloom on the plains of North America in the infamous "Tornado Alley" stretching from the Midwest to Texas. But the seas have their own tornado alleys.
Tornadoes born on the water are called waterspouts. Like land-based tornadoes, they feed on warm, moist, unstable air. Where winds shear past each other, a vortex may develop. A waterspout can form when air rising from the warm ocean surface gets tangled up with the vortex, stretching it thousands of feet to the base of a cloud. This causes the air to rotate faster and faster, like a spinning figure skater as she pulls her arms in toward her body.
Typically, waterspouts live from 2 to 20 minutes and can produce brief bursts of wind up to hurricane force. Though their winds are not usually as powerful and deadly as those of their land-lubber cousins, waterspouts can still destroy: In 1980, a waterspout over San Antonio Bay in Texas chewed up a shrimp boat and then flipped it over and sank it.
Atlantic hurricanes, the ones that plague the Caribbean and Eastern United States every year from June to November, are born as clusters of thunderstorms in the tropical seas west of Africa. Blown by the trade winds, these hurricane "seedlings" scud across the ocean, drawing energy from the warm water. Cyclones can form when storms reach waters where the temperature of the sea surface rises to 80 degrees Fahrenheit.
As the temperature in the center of the storm rises, more water evaporates and the atmospheric pressure at the storm's center drops. The higher pressure air at the edges of the storm rushes in toward the center, like water spiraling down a bathtub drain. In the Northern Hemisphere, forces generated by Earth's rotation deflect the air into a counterclockwise direction. When the winds reach 38 mph, the disturbance is called a tropical storm. At 74 mph and greater, it is a full-fledged hurricane.
In an average year, about ten tropical storms will form in the Atlantic, but only six of those will graduate to becoming a hurricane. What happens aloft is just as important to the formation of cyclones as the warm water that they feed on. In El Niño years, for instance, unusually strong winds at high altitude literally decapitate the tops of developing hurricanes, which can tower 8 to 10 miles into the sky.
Each year, a team of researchers at Colorado State University led by meteorologist William Gray offer a prediction for the coming Atlantic hurricane season. They use a statistical technique based on the number of storms seen in the past given certain conditions. Gray's "hurricane predictors" include the presence of El Niño. From 1991 to 1994, repeated El Niños fostered wind conditions that helped to suppress hurricane formation. Other predictors include the amount of warm-water fuel available in the Caribbean and the climate of West Africa, where hurricane seedlings first sprout.
The forecast for 1999 calls for a relatively active Atlantic hurricane season, with 14 named storms, 9 hurricanes, and 4 intense hurricanes -- approximately as intense as the 1998 season. Gray has been relatively successful over the years. In 1998, he predicted 14 named storms and 9 hurricanes; the season saw 14 storms and 10 hurricanes.
-- By Daniel Pendick | <urn:uuid:839e2917-8b73-47b0-b528-8bc9001c74be> | 3.75 | 765 | Knowledge Article | Science & Tech. | 46.250304 |
Web edition: February 21, 2013
About 100 years ago, researchers discovered a large numbers of very small particles slamming into Earth’s upper atmosphere at high speeds. The mystery particles arrived from all directions. They came from an unknown source apparently outside our solar system. Scientists called them “cosmic rays.”
Now, a century later, a team of scientists has found the origins of most cosmic rays. They are born from clouds of gas surrounding the ancient and massive explosions of distant stars. | <urn:uuid:3e118302-e277-40c3-a9fe-b28fa3c68dbb> | 3.71875 | 102 | Truncated | Science & Tech. | 51.619431 |
Inspired by the internet comic “The Up-Goer Five”, which used only the 1,000 most commonly used words to describe the Saturn V Rocket, scientists across the internet are attempting to describe their work using the just this small set of words. And it’s tough! But one of Brookhaven’s atmospheric scientists was up to the challenge. Alistair Rogers, who works in our Environmental Sciences Department, gives it a go:
Understanding change at the top of the world so we’ll know what is going to happen later
When we drive cars and warm our homes we give out bad stuff that ends up in the air. The bad stuff in the air makes our world warmer, which is not good. Every year there is more bad stuff in the air, and our world gets a little bit warmer. Some people pretend this is not happening, they are wrong.
The green things that live outside suck up the bad stuff in the air that we give out when we drive our cars and use it to grow bigger. This is good because the green things are slowing down the warming of our world. When the green things die, tiny life forms in the ground eat them and return the bad stuff back to the air, this is normal.
Up near the top of the world it is really cold and lots of old dead green things have been stuck in ice in the ground for a very long time. When the dead green things are stuck in ice the tiny life forms can’t eat them and the bad stuff is stuck where it can’t make the world hotter. When ice gets warmed up it starts to go away and when it does the tiny life forms in the ground can eat the old dead green things and give out the bad stuff that makes our world warmer. When the world gets warmer more ice goes away, more dead green stuff gets eaten and more bad stuff ends up in the air which makes the world get warmer, and so on. This could make the world get hotter very quickly, and we need to know more about it.
To help work out what might happen at the top of the world years from now we are trying to understand as much as we can about the way the ice goes away, the green things that grow outside and the tiny life forms that eat them. When we know some more about this stuff we can put what we have learnt in a big thinking box (a bit like the one you are using to read this) and use it to tell us what will happen years from now. | <urn:uuid:df24036f-866b-4911-af3b-d2202f1b983e> | 2.953125 | 520 | Personal Blog | Science & Tech. | 70.303213 |
Long-finned pilot whale
The long-finned pilot whale (Globicephala melas) is one of the two species of cetacean in the genus Globicephala. It belongs to the oceanic dolphin family (Delphinidae), though its behavior is closer to that of the larger whales.
Like the orca, the long-finned pilot whale is really a dolphin. It has a bulbous forehead and is jet black or dark grey with grey or white markings on throat and belly and sometimes behind dorsal fin and eye. The dorsal fin is sickle shaped. The long flippers are about 15 to 20 percent of total body length. It is sometimes known as the pothead whale because the shape of its head reminded early whalers of black cooking pots. Females reach sexual maturity at about 3.7 meters and 6 to 7 years of age. Males need about twice as long to reach sexual maturity at about 4.6 meters and 12 years of age. An adult whale weighs 1.8 to 3.5 tonnes.
They are very social, family animals and may travel in groups of up to a hundred. A dominant female is mostly acting as a leader. These groups socialize with common bottlenose dolphins, Atlantic white-sided dolphins and Risso's dolphins. An adult whale needs about 50 kilograms (110 pounds) of food a day, which consists mostly of cephalopods and to a lesser amount of fish. Pilot whales generally take several breaths before diving for a few minutes. Feeding dives may last over ten minutes. They are capable of diving to depths of 600 meters, but most dives are to a depth of 30-60 meters.
Gestation lasts approximately 12 to 15 months and calving occurs once every 3 to 5 years. Calves are generally 1.8 meters (6 feet) at birth, and weigh about 102 kilograms (225 pounds). The calf nurses for up to 27 months, with some evidence for longer lactation and extensive mother calf bonds. Most calves are born in the summer, though some calving occurs throughout the year. The males may compete for mates with fights involving butting, biting, and ramming. Mating also involves these activities, and some females carry scars from bites inflicted by males during the breeding season. Females have been observed to have calves as late as 55 years old, and lactate as late as 61. This evidence indicates that females may nurse their last calf until puberty (up to 10 years in males).
Communication and echolocation consist of a wide sound range from three to 18 kHz. These sounds are produced 14 to 40 times a minute.
Long-finned pilot whales are very active and can often be seen lobtailing and spyhopping. The younger ones also breach, but this is rare in adults. long-finned pilot whales often strand themselves on beaches - because they have strong family bonds, when one animal strands, the rest of the pod tends to follow.
- ^ Mead, James G.; Brownell, Robert L., Jr. (16 November 2005). "Order Cetacea (pp. 723-743)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14300052.
- ^ Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. (2008). Globicephala melas. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 26 February 2009.
No one has provided updates yet. | <urn:uuid:b9b4ba9a-9189-4862-a08f-ddc17780159c> | 3.515625 | 843 | Knowledge Article | Science & Tech. | 72.750745 |
Decadal Climate and Global Change Research
The Climate Diagnostics Center contributes to understanding the variations in Earth's climate system on decadal to centennial time scales. Research includes process and model simulation studies to elucidate the relation between changes in the atmosphere and those in the ocean. CDC scientists seek to provide physical and dynamical understanding of observed long term climate variations and change through analysis of hierarchies of designed GCM experiments. These include atmospheric models forced by SSTs, ocean models forced by wind stress, and coupled ocean-atmosphere GCMs, including runs forced by greenhouse gases.
Our investigations have focused on determining fundamental processes responsible for decadal climate variability and change, and assessing whether the latter are due to human influences or natural variability. According to the Third Assessment Report of the IPCC, it is now very likely that global temperatures during the 1990s were the highest since 1861. The same appears to be true for tropical sea surface temperatures, and the areal coverage of the so-called oceanic warm pool (SSTs > 28.5C) (Fig. 5.1, top). CDC scientists are diagnosing relationships between this tropical ocean warming, the global atmospheric circulation and recent climate change.
CDC is engaged in understanding how slow changes in climate affect interannual variability. One key question is determining whether the warm pool change over the equatorial west Pacific impacts the statistics of El Niño/Southern Oscillation (ENSO) in the eastern Pacific. It is evident that the strongest El Niño events in the instrumental record have occurred in recent decades (Fig. 5.1, middle); we are assessing if this is a signature of climate change or merely random fluctuations. The global impacts of ENSO have also changed in recent decades. A fundamental question being pursued at CDC is whether the ENSO teleconnections diagnosed from historical data of the 19th and 20th centuries will be accurate depictions of ENSO impacts in this new, unique century of human induced climate change.
CDC scientists are also studying the origin and climatic impact of midlatitude ocean changes. Most dramatic among these is the multi-decadal variability in SSTs over the Pacific poleward of 30N (Fig. 5.1, bottom), an index of which has been termed the Pacific-Decadal Oscillation (PDO). The apparent long time scale of this oceanic behavior is quite different from that of the ENSO time series. Nonetheless, our analysis shows a strong relation between the two on interannual time scales, and an intriguing question is the extent of their coupling on multi-decadal scales. Likewise, the low frequency variations of North Pacific SSTs since 1950 have atmospheric counterparts, including changes in the oceanic storm track and the strength of the upper tropospheric westerly jet. CDC scientists are studying the nature of air-sea interaction over the North Pacific, and assessing to what extent the diagnostic relations mentioned above entail predictability. | <urn:uuid:fb259d0a-3e4a-4975-8e81-06ce6592a41b> | 2.96875 | 601 | Academic Writing | Science & Tech. | 28.590263 |
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Four radiative transfer equations for Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) bands 11, 12, 13, and 14 are built involving six unknowns (average atmospheric temperature, land surface temperature, and four band emissivities), which is a typical ill-posed problem. The extra equations can be built by using linear or nonlinear relationship between neighbor band emissivities because the emissivity of every land surface type is almost constant for bands 11, 12, 13, and 14. The neural network (NN) can make full use of potential information between band emissivities through training data because the NN simultaneously owns function approximation, classification, optimization computation, and self-study ability. The training database can be built through simulation by MODTRAN4 or can be obtained from the reliable measured data. The average accuracy of the land surface temperature is about 0.24 K, and the average accuracy of emissivity in bands 11, 12, 13, and 14 is under 0.005 for test data. The retrieval result by the NN is, on average, higher by about 0.7 K than the ASTER standard product (AST08), and the application and comparison indicated that the retrieval result is better than the ASTER standard data product. To further evaluate self-study of the NN, the ASTER standard products are assumed as measured data. After using AST09, AST08, and AST05 (ASTER Standard Data Product) as the compensating training data, the average relative error of the land surface temperature is under 0.1 K relative to the AST08 product, and the average relative error of the emissivity in bands 11, 12, 13, and 14 is under 0.001 relative to AST05, which indicates that the NN owns a powerful self-study ability and is capable of suiting more conditions if more reliable and high-accuracy ASTER standard products can be compensated.
Geoscience and Remote Sensing, IEEE Transactions on (Volume:46 , Issue: 1 )
Date of Publication: Jan. 2008 | <urn:uuid:e60e78a5-a383-4f4d-9fff-62319ec9259f> | 2.78125 | 430 | Academic Writing | Science & Tech. | 32.94125 |
The recent discovery of HD85512b only 36 light years from Earth has promising attributes to harbor life. Assuming we want to travel there, we cannot instantaneously jump to light speed, (StarTrek euphemisms aside), we'll have to accelerate the conventional way by building momentum.
Now, how long would it take to first reach the speed of light at a rate of acceleration that wouldn't kill the occupants of the spacecraft ? (We can't continuously accelerate at 4g's for prolonged periods because it would eventually kill you from physical stress.) Secondly, then given the time to accelerate to the speed of light, how long would it then take to travel the remaining distance and reach our new utopia ? | <urn:uuid:18bbcab9-f68d-4070-871d-6b9365f2ccd6> | 3.078125 | 142 | Q&A Forum | Science & Tech. | 46.180521 |
Mission Type: Orbiter
Launch Vehicle: Delta II Heavy 2925H-9.5 including Star 48 upper stage
Launch Site: Cape Canaveral Air Force Station, Fla., Pad 17B, USA
NASA Center: Jet Propulsion Laboratory
Spacecraft Mass: 1,217.7 kilograms (2,684.6 pounds) at launch, consisting of 747.1-kg (1,647.1-pound) spacecraft, 425 kg (937 pounds) xenon propellant and 45.6 kg (100.5 pounds) hydrazine propellant
1) Framing Camera
2) Gamma Ray and Neutron Detector
3) Visible and Infrared Mapping Spectrometer
Spacecraft Dimensions: 1.64 meters (5.4 feet) long, 1.27 meters (4.2 feet) wide and 1.77 meters (5.8 feet) high. When deployed, solar array is 20 meters (65 feet) long tip to tip.
Antenna Diameter: 1.52 meters (5 feet) in diameter.
Total Cost: $357.5 million total (not including launch vehicle), consisting of $281.7 million spacecraft
development and $75.8 million mission operations
-Dawn Launch Press Kit, September 2007
The Dawn spacecraft combines innovative state-of-the-art technologies pioneered by other recent missions with off-the-shelf components and, in some cases, spare parts and instrumentation left over from previous missions.
Most systems on the spacecraft are redundant, meaning that there is a backup available if the main system encounters a problem. Automated onboard fault protection software will sense any unusual conditions and attempt to switch to backups.
With its solar array in the retracted position (for launch), the Dawn spacecraft is 2.36 meters (7 feet, 9 inches) long -- about as long as a large motorcycle. With its wide solar arrays extended, Dawn is about as long as a tractor-trailer at 19.7 meters (65 feet).
During its nearly decade-long mission, the Dawn mission will study the asteroid Vesta and dwarf planet Ceres, celestial bodies believed to have accreted early in the history of the solar system. The mission will characterize the early solar system and the processes that dominated its formation.
During the earliest epochs of our solar system, the materials in the solar nebula varied with their distance from the sun. As this distance increased, the temperature dropped, with terrestrial bodies forming closer to the sun, and icy bodies forming farther away.
The asteroid Vesta and the recently categorized dwarf planet Ceres have been selected because, while both speak to conditions and processes early in the formation of the solar system, they developed into two different kinds of bodies. Vesta is a dry, differentiated object with a surface that shows signs of resurfacing. It resembles the rocky bodies of the inner solar system, including Earth.
Ceres, by contrast, has a primitive surface containing water-bearing minerals, and may possess a weak atmosphere. It appears to have many similarities to the large icy moons of the outer solar system.
By studying both these two distinct bodies with the same complement of instruments on the same spacecraft, the Dawn mission hopes to compare the different evolutionary path each took as well as create a picture of the early solar system overall. Data returned from the Dawn spacecraft could provide opportunities for significant breakthroughs in our knowledge of how the solar system formed.
To carry out its scientific mission, the Dawn spacecraft will carry three science instruments whose data will be used in combination to characterize these bodies. These instruments consist of a visible camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer. In addition to these instruments, radiometric and optical navigation data will provide data relating to the gravity field and thus bulk properties and internal structure of the two bodies.
During its orbital studies, Dawn will investigate Vesta's and Ceres' internal structure, density and homogeneity by measuring their mass, shape, volume and spin state with radiometric tracking and imagery, and determine elemental and mineral composition. From this information scientists can determine the relationship between meteorites and their parent bodies, and the thermal histories of the bodies. From images of the surface, knowledge of their bombardment, tectonic and possibly volcanic history will be revealed.
In particular, the mission's scientific objectives are to:
- Investigate the internal structure, density and homogeneity of two complementary protoplanets, 1 Ceres and 4 Vesta, one wet and one dry.
- Determine surface morphology and cratering via near-global surface imagery in three colors at Vesta and in three at Ceres.
- Perform radio tracking to determine mass, gravity field, principal axes, rotational axis and moments of inertia of both Vesta and Ceres.
- Determine shape, size, composition and mass of both Vesta and Ceres.
- Determine thermal history and size of each body's core.
- Determine the spin axis of both Vesta and Ceres.
- Understand the role of water in controlling asteroid evolution.
- Test the prevailing scientific theory that Vesta is the parent body for a class of stony meteorites known as howardite, eucrite and diogenite, or "HED," meteorites; determine which, if any, meteorites come from Vesta.
- Provide a geologic context for HED meteorites.
- Obtain surface coverage with the mapping spectrometer from 0.25- to 5.0-micron wavelengths.
- Obtain neutron and gamma ray spectra to produce maps of the surface elemental composition of each object, including the abundance of major rock-forming elements (oxygen, magnesium, aluminum, silicon, calcium, titanium and iron), trace elements (gadolinium and samarium), and long-lived radioactive elements (potassium, thorium and uranium). | <urn:uuid:5fb6f5e2-5c9c-4e6a-9213-2945cc1fac71> | 2.890625 | 1,213 | Knowledge Article | Science & Tech. | 40.520392 |
Light from fireflies and other living things is called bioluminescence. There are many bioluminescent things in nature — plants, animals, and bacteria.
The glowing plants include only a few kinds, such as certain toadstools and molds. But animals that light up are more numerous; they range from tiny one-celled sea creatures to sponges, clams, worms, and insects. The most numerous glowing forms of life are found in the salt water of oceans. The most familiar forms are found on land — fireflies, glowworms, and fox fire fungus.
Bioluminescence is called "cold" light to distinguish it from incandescence, or heat-giving light. (For example, electric light bulbs, oil lamps, and candles give off "hot" light.) Living plants and animals could not produce incandescent light without being burned up. Their light is caused by chemicals combining in such a way that little or no measurable heat is given off.
The substance that gives off the light in living things is called luciferin. This "glowing" chemical was named in 1887 by one of the earliest scientists to study living light, Raphaël Dubois, of France. Dubois named this chemical substance "luciferin," meaning "light bearer." Through his experiments using the glowing fluid taken from a clam, Dubois found that the light was caused by a team of chemicals working together. Luciferin would not light up except in the presence of a second chemical, which Dubois called "luciferase."
Scientists have since learned that living light is produced when luciferin and oxygen combine in the presence of luciferase. Other substances are also needed to produce light in some living things, such as adenosine triphosphate (ATP) in fireflies. It is the additional substances that give the light a range of color from yellow to blue, green, and red.
In some cases, the function of the light seems obvious. Marine fireworms use glowing light as mating signals. During the mating season, the female fireworms come up from deep waters to the surface of the sea and glow. Seeing the light, the males join the females. A mating dance follows and then both sexes release their reproductive cells into the water.
Bulblike organs, called photophores, on the bodies of many deep-sea fish attract mates or prey and illuminate the search for them in the darkness of the ocean depths. Some luminescent fish zigzag through the water with lights flashing to confuse predators and escape being eaten. In other cases, such as the many blind light-emitting deep-sea species, the light seems to have no function.
Much remains to be learned about the chemistry of bioluminescence. Perhaps some day enough will be known to produce this cold light for everyday use instead of the energy-wasting electric light we use now.
(Photo credit: OAR/National Undersea Research Program (NURP); Harbor Branch Oceanographic Institution) | <urn:uuid:472b2145-102c-465a-ac81-a8de94361c16> | 3.9375 | 631 | Knowledge Article | Science & Tech. | 46.614965 |
A related class is the ChoiceFormat (§) class described in the Formatting Messages chapter. It maps ranges of numeric values to strings.
NumberFormat is the abstract base class for all number formats. It provides an interface for formatting and parsing numbers. It also provides methods to determine which locales have number formats, and what their names are. NumberFormat helps format and parse numbers for any locale. Your program can be written to be completely independent of the locale conventions for decimal points or thousands-separators. It can also be written to be independent of the particular decimal digits used or whether the number format is a decimal. A normal decimal number can also be displayed as a currency or as a percentage.
format a number for the current Locale, use one of the static factory
methods to create a format, then call a format method to format it. To
format a number for a different Locale, specify the Locale in the call
to createInstance(). You can control the numbering system to be used for number formatting by creating a Locale that uses the @numbers keyword defined. For example, by default, the Thai locale "th" uses the western digits 0-9. To create a number format that uses the native Thai digits instead, first create a locale with "@numbers=thai" defined. See the description on Locales for details.
The following methods are used for instantiating NumberFormat objects:
To create a format for spelled-out numbers, use a constructor on RuleBasedNumberFormat (§).
Currency formatting, i.e., the formatting of monetary values, combines a number with a suitable display symbol or name for a currency. By default, the currency is set from the locale data from when the currency format instance is created, based on the country code in the locale ID. However, for all but trivial uses, this is fragile because countries change currencies over time, and the locale data for a particular country may not be available.
For proper currency formatting, both the number and the currency must be specified. Aside from achieving reliably correct results, this also allows to format monetary values in any currency with the format of any locale, like in exchange rate lists. If the locale data does not contain display symbols or names for a currency, then the 3-letter ISO code itself is displayed.
The locale ID and the currency code are effectively independent: The locale ID defines the general format for the numbers, and whether the currency symbol or name is displayed before or after the number, while the currency code selects the actual currency with its symbol, name, number of digits, and rounding mode.
In ICU and Java, the currency is specified in the form of a 3-letter ISO 4217 code. For example, the code "USD" represents the US Dollar and "EUR" represents the Euro currency.
In terms of APIs, the currency code is set as an attribute on a number format object (on a currency instance), while the number value is passed into each format() call or returned from parse() as usual.
The functionality of Currency and setCurrency() is more advanced in ICU than in the base JDK. When using ICU, setting the currency automatically adjusts the number format object appropriately, i.e., it sets not only the currency symbol and display name, but also the correct number of fraction digits and the correct rounding mode. This is not the case with the base JDK. See the API references for more details.
There is ICU4C sample code at icu/source/samples/numfmt/main.cpp which illustrates the use of NumberFormat.setCurrency().
You can also control the display of numbers with methods such as getMinimumFractionDigits. If you want even more control over the format or parsing, or want to give your users more control, cast the NumberFormat returned from the factory methods to a DecimalNumberFormat. This works for the vast majority of countries.
You can also use forms of the parse and format methods with ParsePosition and UFieldPosition to enable you to:
For example, you can align numbers in two ways:
NumberFormat can produce many of the same formats as printf.
DecimalFormat is a NumberFormat that converts numbers into strings using the decimal numbering system. This is the formatter that provides standard number formatting and parsing services for most usage scenarios in most locales. In order to access features of DecimalFormat not exposed in the NumberFormat API, you may need to cast your NumberFormat object to a DecimalFormat. You may also construct a DecimalFormat directly, but this is not recommended because it can hinder proper localization.
For a complete description of DecimalFormat, including the pattern syntax, formatting and parsing behavior, and available API, see the ICU4J DecimalFormat API or ICU4C DecimalFormat API documentation.
DecimalFormatSymbols specifies the exact characters a DecimalFormat uses for various parts of a number (such as the characters to use for the digits, the character to use as the decimal point, or the character to use as the minus sign).
This class represents the set of symbols needed by DecimalFormat to format numbers. DecimalFormat creates its own instance of DecimalFormatSymbols from its locale data. The DecimalFormatSymbols can be adopted by a DecimalFormat instance, or it can be specified when a DecimalFormat is created. If you need to change any of these symbols, can get the DecimalFormatSymbols object from your DecimalFormat and then modify it.
RuleBasedNumberFormat can format and parse numbers in spelled-out format, e.g. "one hundred and thirty-four". For example:
RuleBasedNumberFormat is based on rules describing how to format a number. The rule syntax is designed primarily for formatting and parsing numbers as spelled-out text, though other kinds of formatting are possible. As a convenience, custom API is provided to allow selection from three predefined rule definitions, when available: SPELLOUT, ORDINAL, and DURATION. Users can request formatters either by providing a locale and one of these predefined rule selectors, or by specifying the rule definitions directly.
Unlike the other standard number formats, there is no corresponding factory method on NumberFormat. Instead, RuleBasedNumberFormat objects are instantiated via constructors. Constructors come in two flavors, ones that take rule text, and ones that take one of the predefined selectors. Constructors that do not take a Locale parameter use the current default locale.
The following constructors are available:
RuleBasedNumberFormat can be used like other NumberFormats. For example, in Java:
Rule descriptions can provide multiple named rule sets, for example, the rules for en_US spellout provides a '%simplified' rule set that displays text without commas or the word 'and'. Rule sets can be queried and set on a RuleBasedNumberFormat. This lets you customize a RuleBasedNumberFormat for use through its inherited NumberFormat API. For example, in Java:
You can also format a number specifying the ruleset directly, using an additional overload of format provided by RuleBasedNumberFormat. For example, in Java:
The following example provides a quick look at the RuleBasedNumberFormat rule syntax.
These rules format a number using standard decimal place-value notation, but using words instead of digits, e.g. 123.4 formats as 'one two three point four':
Rulesets are invoked by first applying negative and fractional rules, and then using a recursive process. It starts by finding the rule whose range includes the current value and applying that rule. If the rule so directs, it emits text, including text obtained by recursing on new values as directed by the rule. As you can see, the rules are designed to accomodate recursive processing of numbers, and so are best suited for formatting numbers in ways that are inherently recursive.
C/C++: See icu/source/samples/numfmt/ in the ICU source distribution for code samples showing the use of ICU number formatting. | <urn:uuid:edb84fe4-0a0e-476e-be4e-8896449e2c7d> | 4.0625 | 1,693 | Documentation | Software Dev. | 32.238857 |
Science Fair Project Encyclopedia
RNA world hypothesis
The RNA world hypothesis proposes that RNA was actually the first life-form on earth, later developing a cell membrane around it and becoming the first prokaryotic cell. This hypothesis is supported by the RNA's ability to store, transmit, and duplicate genetic information, just like DNA does. RNA can also act as a ribozyme (an enzyme made of ribonucleic acid). Because it can reproduce on its own, performing the tasks of both DNA and proteins (enzymes), RNA is believed to have once been capable of independent life.
The phrase "RNA World" was first used by Walter Gilbert in 1986. However, the theory of independent RNA life is much older and can be found in Carl Woese's book The Genetic Code (New York: Harper and Row, 1967).
The base pair
RNA and DNA are made of long stretches of specific nucleotides, often referred to as "bases", attached to a sugar-phosphate backbone. The RNA world hypothesis holds that in the primordial soup / primordial sandwich there existed free-floating nucleotides. These nucleotides would regularly form bonds with one another, but the chains would often break apart because the change in energy was so low. However, certain sequences of base pairs have catalytic properties that actually lower the energy of their chain being created, causing them to stay together for longer periods of time. As each chain grew longer it attracted more matching nucleotides faster, causing chains to now form faster than they were breaking down.
These chains are proposed as the first, primitive forms of life. In an RNA world, different forms of RNA compete with each other for free nucleotides and are subject to natural selection. The most efficient molecules of RNA, the ones able to efficiently catalyze their own reproduction, survived and evolved, forming modern RNA.
Competition between RNA may have favored the emergence of cooperation between different RNA chains, opening the way for the formation of the first proto-cell. Eventually, RNA chains randomly developed with catalytic properties that help amino acids bind together (peptide-bonding). These amino acids could then assist with RNA synthesis, giving those RNA chains that could serve as ribozymes the selective advantage. Eventually DNA, lipids, carbohydrates, and all sorts of other chemicals were recruited into life. This led to the first prokaryotic cells, and eventually to life as we know it.
Nucleic acid fragility
At first glance, the RNA world hypothesis seems implausible because, in today's world, large RNA molecules are inherently fragile and can easily be broken down into their constituent nucleotides with hydrolysis. Even without hydrolysis RNA will eventually break down from background radiation. (Pääbo 1993, Lindahl 1993).
A proposed alternative to RNA in an "RNA World" is the peptide nucleic acid, PNA. PNA is more stable than RNA and appears to be more readily synthesised in prebiotic conditions, especially where the synthesis of ribose and adding phosphate groups are problematic.
Additionally, in the past a given RNA molecule might have "lived" longer then than it can today. Ultraviolet light can cause RNA to polymerize while at the same time breaking down other types of organic molecules that could have the potential of catalyzing the break down of RNA (RNAses ), suggesting that RNA may have been a relatively common substance on early earth. This aspect of the theory is still untested and is based on a constant concentration of sugar-phosphate molecules.
The RNA world hypothesis, if true, has important implications for the very definition of life. Life so far has been largely defined in terms of DNA and proteins; in today's world, DNA and proteins seem to be the dominant macromolecules in the living cell, with RNA serving only to aid in creating proteins from the DNA blueprint. But the RNA world hypothesis places RNA at center-stage when life originated, therefore requiring that we define life primarily in terms of RNA and the set of strategies that RNA has used to perpetuate itself.
In 2001, the RNA world hypothesis was given a major boost with the deciphering of the 3-dimensional structure of the ribosome, which revealed the key catalytic sites of ribosomes to be composed of RNA, with proteins playing only a structural role in holding the ribosomal RNA together. Specifically, the formation of the peptide bond, the reaction that binds amino acids together into proteins, is now known to be catalyzed by RNA. This finding suggests that RNA molecules were most likely capable of generating the first proteins.
The base cytosine does not have a plausible prebiotic simulation method because it is so easily undergoes hydrolysis.
Prebiotic simulations making nucleotides have conditions incompatible with those for making sugars (lots of formaldehyde). So they must somehow be synthesized, then brought together. However, they don't react in water. Anhydrous reactions will bind with purines, but only 8% of them are joined with the correct carbon atom on the sugar joined to the correct nitrogen atom on the base. Pyrimidines, however, will not react with ribose, even anhydrously.
Then phosphate must be introduced, but in nature phosphate in solution is extremely rare because it is so readily precipitated. After being introduced, the phosphate must combine with the nucleoside and the correct hydroxyl must be phosphorylated.
For the nucleotides to form RNA, they must be activated themselves. Activated purine nucleotides will form small chains on a pre-existing template of all-pyrimidine RNA. However, this does not happen in reverse because the pyrimidine nucleotides do not stack well.
A.G. Cairns-Smith criticized writers for exaggerating the implications of the Miller-Urey experiment. He argued that the experiment showed, not the possibility that nucleic acids preceded life, but its implausibility. According to Cairns-Smith, the process of constructing nucleic acids would require eighteen distinct conditions and events that would have to occur continually over millions of years in order to build up the required quantities.
One of the leading researchers into RNA world models, Gerald Joyce , wrote:
- The most reasonable assumption is that life did not start with RNA .... The transition to an RNA world, like the origins of life in general, is fraught with uncertainty and is plagued by a lack of experimental data.
- Cairns-Smith, A. G. Genetic Takeover: And the Mineral Origins of Life. ISBN 0-52123-312-7
- Lindahl, T., 1993. Instability and decay of the primary structure of DNA, Nature 362(6422):709–715.
- Pääbo, S. 1993. Ancient DNA, Scientific American 269(5):60–66.
- "SELF-REPLICATION: Even peptides do it" by Stuart A. Kauffman
- Nobel prize website on the RNA world
- American Scientist Online article from 1995 discussing origin of life and RNA world
- The RNA World: A Critique (Origins & Design 17(1):9–16, 1996) (Intelligent Design publication, co-authored by Dean Kenyon, former leader in chemical evolution)
- Origin of Life: Instability of Building Blocks(Vol. 13, No. 2 of the Creation Ex Nihilo Technical Journal) by Young Earth Creationist Jonathan Sarfati.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details | <urn:uuid:8538309a-94d7-497e-afa3-fcb1b9f39ccb> | 4.25 | 1,586 | Knowledge Article | Science & Tech. | 38.627713 |
Basic Physics behind Viscometry
This video shows Anton Paar eLearning course: basics of viscometry. This course gives a solid introduction to the basic physics behind viscometry, the practice of measuring certain materials’ viscosity. According to Joe Flow, viscosity is actually a part of viral science, which is called rheology.
Run Time - 1:44min | <urn:uuid:be4cfba2-a41f-481c-97c7-67167d50ec7b> | 2.984375 | 81 | Truncated | Science & Tech. | 26.088239 |
Dawn is a NASA mission managed by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. The University of California, Los Angeles, is responsible for overall Dawn mission science.
The space probe’s two destinations are the protoplanet Vesta and the dwarf planet Ceres that circle the Sun within the so-called aseroid belt between the orbits of Mars and Jupiter. The Max Planck Institute for Solar System Research has contributed the mission’s on borard camera system. The two identical cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research with significant contributions by the Institute for Planetary Research of the German Aerospace Center (DLR) and in coordination with the Institute of Computer and Communication Network Engineering of the Technical University Braunschweig.
But the Dawn mission, that was launched in September 2007 is far more than a journey to two distant bodies. It is a journey back in time to the beginnings of our solar system more than 4,5 billion years ago. Vesta and Ceres are among the largest survivors from this early phase of planet formation. All other larger bodies either merged to form planets or broke apart due to heavy collisions. The internal structure and the surfaces of Vesta and Ceres, however, have remained mostly unchanged. They therefore offer scientists the opportunity to take look back into time.
On 27. September 2007 the space probe started on its long journey.
It arrived at its first scientific destination, the protoplanet Vesta, on 16. July 2011. In the following 13 months, Dawn entered into orbits that were closer and closer to Vesta’s surface. Between December 2011 and May 2012, only 210 kilometers separated both.
Dawn will arrive at Ceres in early 2015. A beneficial constellation of both bodies allows for this relatively short travelling time. During the following months, Dawn will approach Ceres’ surface up to a distance of approximately 700 kilometers.
In order to save fuel on its way to the asteroid belt, Dawn flew closely by Mars in February 2009. Such a maneuver allows the spacecraft to pick up momentum. In addition, the swing-by was a welcome opportunity to test the scientific instruments on a relatively close target. The cameras onboard obtained detailed images of Mars’ surface during fly-by.
27. September 2007: launch
18. February 2009: Mars Flyby
16. July 2011: arrival at Vesta
5. September 2012: departure from Vesta
February 2015: arrival at Ceres
July 2015: departure from Ceres
Dawn carries three scientific instruments on board: The Camera system FC, the detector for gamma-radiation and neutrons GRaND, and the spectrograph VIR.
GRaND was built by the Los Alamos National Laboratory in New Mexico (USA) and is operated by the Planetary Science Institute, Tucscon, Arizona.
The VIR spectrograph studies the visible and infrared solar radiation that the asteroids reflect into space. This data contains information about the mineralogical composition. VIR was provided by the Italian space agency ASI and developed and built by Galileo Avionica.
In addition, Vesta’s gravity field will be determined using high-accuracy navigation to reveal the structure of Vesta’s interior.
The targets of the Dawn mission could not be more different: While Vesta once had a hot, molten interior that produced lava flows, Ceres has always been a cold body, under whose surface possibly frozen water can be found. In addition, both bodies allow for a look back into an early phase of our solar system. Both asteroids are among the largest survivors from this early phase of planet formation. more...
Dawn is a NASA mission managed by the Jet Propulaion Laboratory (JPL) that will reach the asteroids Vesta and Ceres within the next years. The space probe will encounter its first destination, the asteroid Vesta, in the summer of 2011. Presumably at the end of July, Dawn will start orbiting Vesta and deliver its first high-resolution images of the surface. more...
The mission's success crucially depends on the two cameras, Dawn's eyes. The cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research with significant contributions by the Institute for Planetary Research of the German Aerospace Center (DLR) and in coordination with the Institute of Computer and Communication Network Engineering of the Technical University Braunschweig. more... | <urn:uuid:182b2412-5153-4abd-a6e9-e51db1352769> | 3.734375 | 927 | Knowledge Article | Science & Tech. | 40.56218 |
Reader comments are listed below. Comments are currently closed and new comments are no longer being accepted.
It does seem that you ought to be able to reference change in thermodynamic temperature of a specific element to define moles. If you have two different amounts of a specified element at known thermodynamic temperatures, the difference in the temperature change caused by the transfer of all of the heat from amount x to amount y will be proportional to the difference in the number of moles.
I don't like to think of Kelvins being unrelated to the other guys in the family.
This diagram is helpful. http://en.wikipedia.org/wiki/File:SI_base_unit.svg
You got it. And elaborating a little, we don't need to measure the number of atoms exactly to get rid of the artifact. While we cannot determine the precise 23+-digit number, we can estimate it so exactly that the imprecision wouldn't be enough for us to notice given our current ability to measure mass. Then we keep our estimated count as the "true" kg. It's our unit, after all, and we can define it any way we like as long as we don't mess up existing scales. In the future we refine our measuring tools using the atom count, retiring the platinum/iridium chunk to a museum.
I think I am following... but I am not sure. Can I repeat what you said in my own way of thinking about it and you tell me if I have got it right....
So we need both the big and the small, because either one alone doesn't do all the jobs.
The small (Example is the atomic mass unit, which is 1/12 of the mass of a carbon 12 atom at rest, which is also what Commenter Morani ya Simba said) has the virtue of being a precise "invariant", and the convenience of not having to refer to a block of metal in a lab which requires cleaning ever so often.
The big has the virtue of giving us a "rough start" for measuring bigger things. In this case the example of a "big" is that metal block in the French lab. There are two things to be noted about this metal block: (a) Although it is theoretically possible to count the number of atomic units in it, that number is so huge it is kind of silly to do it, especially the job is already done by the "Small Methoid" using invariant atomic units in Example given; (b) Although the periodic cleaning is necessary to keep the block mass as close to "invariant" as possible (only it will never be because we don't know the number of atom units in it because we haven't counted), it has the virtue of being a measurement of weight, not mass, AND beginning from there , we can make weight measuring scales to weigh all things big and small, from an anchovy to a whale.
Something like that. Did I get it right?
BTW, thank you for the continued lesson. Appreciate it very much indeed.
This must be a modesty contest we are doing! (Referring to your referring to yourself as a "lesser educated person".)
I actually wanted to understand the first reference point for the measurement of anything. For some reason, it seems such a fascinating subject to me. I can't explain further why I find it fascinating except to point out it is so basic to everything else we do. :)
Scientifically this is an entirely unsatisfactory way to define a unit of mass. It should be defined as an energy equivalence at rest.
You're right, but the point is to use physical material units of mass that are invariant, not some sphere that needs cleaning. The atomic mass unit, which is 1/12 of the mass of a carbon 12 atom at rest is a good example. This is invariant, and the reference atom won't gather a film and need cleaning. But, it's also really small. We need a human-sized unit. That would involve defining, say, the KG as so many atomic units, and there is such a definition, based on that Parisian sphere, but it's not very precise, since we can't count all the atoms in it. The goal, then, is to determine, very exactly, how many atomic units (reliable, consistent, but small) are in the reference KG (big, useful, but unreliable).
What will philosophers do when such nice putative examples of a priori contingency are relegated to the annals of history?
In reply to Ashbird ( Jan11th )from a lesser educated person
I think you are correct.
Isn't exacly that what the 'fore fathers/mothers ' of measuremebt have done ?
Created a standard physical matter, to which others relate to ?
Yes! @VariableZ, it helps! You answered my original question! Mainly I needed to find out how to correctly think about the problem, not that the answer might be something I can comprehend.
Now I have another question. Answer if you have time. Ignore if you don't. I feel very obliged already.
So if there is the "count out atoms" way to measure mass and the "watt balance" way to measure force, why do we need the thing kept in the French lab? I mean for that kind of precision, those two alternatives would suffice, wouldn't it?
very interesting comment. I am refering to an explanation given by Bertrand Russell, in his book ABC of Relativity, an explanationto Ienstein's theory
What confuses me in your reasoning, is that compression of time and space is only apparent to the observer,on the platform, of an approaching train travelling at 60 percent of the speed of light (BR )and not to the passengers on the train, observing the passengers on the platform.
I must add that I am still trying to ncome to terms with the great man's theory and Russell;s explanation.
Nevertheless, this article is very interesting
This may be a very foolish question, but since e=mc^2, and both energy and the speed of light can be defined in "objective" terms (that is, not tied to some man-made object), could one not define a kilogramme as being enough of some form of stuff to produce y joules of energy (or, since the numbers are big, x times the amount of stuff neded to produce y joules of energy)? Then, every time you really need to work out mass with great precision, you'd just need to count the number of atoms of the relevant stuff, and multiply it by x.
Is there some bit of basic physics I'm missing? Can you count atoms like this, and if not, would using molecules work?
That is true to an extent, but your argument depends on the definition of time and distance. A measurement of distance, of course, is not the same as a measurement of displacement. The article is right, however, that humans have defined the meter (as the distance travelled by light in 1/299,792,458 ths of a second), while the second is defined as being the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyper-fine levels of the caesium-133 atom in ground state. Einstein suggested and it was later proved that time and space dilate, but not that the second and the meter change. These are constants defined as units by humans, and as such they will remain, whatever the velocity of the observer.
"Scientists like the metric system partly for its simplicity—everything is based on powers of ten, which makes calculation easy"
So why are there 0.2388459 calories to a Joule and 2.777778e-007 kilowatt hours?
Système international d'unités. (Not "internationale")
A Watt is a perfectly designed instrument or object. Its construction and mode of operation does not need additional energy for all of its functions. Its parts are shaped to be perfectly energetic and operate without energy loss at any given start motion. A Watt continues until perfection is achieved.
The official kilograms remind me of visiting the county museum in tiny Hillsborough, North Carolina, which has a complete set of weights and measures, circa 1760, that had been shipped from England and hauled far inland to the frontier. I'm sure the official kilogram replicas are better-made than these weights, but the concept hasn't changed.
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Alternate name: Spotted Frog
Family: Ranidae, True Frogs view all from this family
Description Short back legs, narrow snout and upturned eyes. Webbed feet. Brown/tan-gray. Dark spots. Dorsolateral ridges. Light stripe on upper jaw. Lower abdomen pale yellow-red.
Dimensions 5.1-10.2 cm. (2-4")
Voice Rapid croaks.
Breeding March-June. Up to 1300 eggs. Egg masses put in water, absorb water and swell up to the size of a softball.
Similar Species Oregon Spotted Frog - Brown/reddish brown/orange. British Columbia through to Washington & Oregon.
Habitat Permanent bodies of water, which can include lakes, ponds, slow-moving streams, and marshes.
Range Alaska and parts of British Columbia to Washington, Idaho, and parts of Wyoming, Nevada, and Utah.
Discussion Dirunal. Likes cooler waters. Needs a source of low-growing vegetation. Grasshoppers, ants, wasps, beetles, and moths included in their diet. | <urn:uuid:fee36fe2-d73a-4d01-81f5-e50af0649fdb> | 3.125 | 231 | Knowledge Article | Science & Tech. | 62.128864 |
Northern Prairie Wildlife Research Center
Reptiles and Amphibians of North Dakota
Gray Tree Frog (Hyla versicolor)
Gray tree frogs have the remarkable capacity to change their color from gray
to brown or green within just a few minutes. They are medium-sized frogs that
can grow to approximately two inches in length. Their toes are tipped with adhesive
discs which enable them to climb and cling to smooth branches and leaves.
They are often seen on roadways hunting for insects on warm, humid, summer
nights. During the day they prefer the shade and protection of trees and shrubs
near water. Their diet consists mainly of insects.
They are found throughout the aspen woodlands of northeastern North Dakota.
Previous Section-- Woodhouse's Toad
Return to Contents
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CREATE AGGREGATE name ( input_data_type [ , ... ] ) ( SFUNC = sfunc, STYPE = state_data_type [ , FINALFUNC = ffunc ] [ , INITCOND = initial_condition ] [ , SORTOP = sort_operator ] ) or the old syntax CREATE AGGREGATE name ( BASETYPE = base_type, SFUNC = sfunc, STYPE = state_data_type [ , FINALFUNC = ffunc ] [ , INITCOND = initial_condition ] [ , SORTOP = sort_operator ] )
CREATE AGGREGATE defines a new aggregate function. Some basic and commonly-used aggregate functions are included with the distribution; they are documented in Section 9.20. If one defines new types or needs an aggregate function not already provided, then CREATE AGGREGATE can be used to provide the desired features.
If a schema name is given (for example, CREATE AGGREGATE myschema.myagg ...) then the aggregate function is created in the specified schema. Otherwise it is created in the current schema.
An aggregate function is identified by its name and input data type(s). Two aggregates in the same schema can have the same name if they operate on different input types. The name and input data type(s) of an aggregate must also be distinct from the name and input data type(s) of every ordinary function in the same schema.
An aggregate function is made from one or two ordinary functions: a state transition function sfunc, and an optional final calculation function ffunc. These are used as follows:
sfunc( internal-state, next-data-values ) ---> next-internal-state ffunc( internal-state ) ---> aggregate-value
PostgreSQL creates a temporary variable of data type stype to hold the current internal state of the aggregate. At each input row, the aggregate argument value(s) are calculated and the state transition function is invoked with the current state value and the new argument value(s) to calculate a new internal state value. After all the rows have been processed, the final function is invoked once to calculate the aggregate's return value. If there is no final function then the ending state value is returned as-is.
An aggregate function can provide an initial condition, that is, an initial value for the internal state value. This is specified and stored in the database as a value of type text, but it must be a valid external representation of a constant of the state value data type. If it is not supplied then the state value starts out null.
If the state transition function is declared "strict", then it cannot be called with null
inputs. With such a transition function, aggregate execution
behaves as follows. Rows with any null input values are ignored
(the function is not called and the previous state value is
retained). If the initial state value is null, then at the first
row with all-nonnull input values, the first argument value
replaces the state value, and the transition function is invoked
at subsequent rows with all-nonnull input values. This is handy
for implementing aggregates like
max. Note that this behavior is only available
when state_data_type is the same
as the first input_data_type.
When these types are different, you must supply a nonnull initial
condition or use a nonstrict transition function.
If the state transition function is not strict, then it will be called unconditionally at each input row, and must deal with null inputs and null transition values for itself. This allows the aggregate author to have full control over the aggregate's handling of null values.
If the final function is declared "strict", then it will not be called when the
ending state value is null; instead a null result will be
returned automatically. (Of course this is just the normal
behavior of strict functions.) In any case the final function has
the option of returning a null value. For example, the final
avg returns null when
it sees there were zero input rows.
Aggregates that behave like
MAX can sometimes be optimized
by looking into an index instead of scanning every input row. If
this aggregate can be so optimized, indicate it by specifying a
sort operator. The basic requirement is
that the aggregate must yield the first element in the sort
ordering induced by the operator; in other words:
SELECT agg(col) FROM tab;
must be equivalent to:
SELECT col FROM tab ORDER BY col USING sortop LIMIT 1;
Further assumptions are that the aggregate ignores null
inputs, and that it delivers a null result if and only if there
were no non-null inputs. Ordinarily, a data type's < operator is the proper sort operator for
MIN, and > is the proper sort operator for
MAX. Note that the optimization will never
actually take effect unless the specified operator is the
"less than" or "greater than" strategy member of a B-tree index
To be able to create an aggregate function, you must have USAGE privilege on the argument types, the state type, and the return type, as well as EXECUTE privilege on the transition and final functions.
The name (optionally schema-qualified) of the aggregate function to create.
An input data type on which this aggregate function
operates. To create a zero-argument aggregate function,
write * in place of the list of
input data types. (An example of such an aggregate is
In the old syntax for CREATE AGGREGATE, the input data type is specified by a basetype parameter rather than being written next to the aggregate name. Note that this syntax allows only one input parameter. To define a zero-argument aggregate function, specify the basetype as "ANY" (not *).
The name of the state transition function to be called for each input row. For an N-argument aggregate function, the sfunc must take N+1 arguments, the first being of type state_data_type and the rest matching the declared input data type(s) of the aggregate. The function must return a value of type state_data_type. This function takes the current state value and the current input data value(s), and returns the next state value.
The data type for the aggregate's state value.
The name of the final function called to compute the aggregate's result after all input rows have been traversed. The function must take a single argument of type state_data_type. The return data type of the aggregate is defined as the return type of this function. If ffunc is not specified, then the ending state value is used as the aggregate's result, and the return type is state_data_type.
The initial setting for the state value. This must be a string constant in the form accepted for the data type state_data_type. If not specified, the state value starts out null.
The associated sort operator for a
MAX-like aggregate. This is just an
operator name (possibly schema-qualified). The operator is
assumed to have the same input data types as the aggregate
(which must be a single-argument aggregate).
The parameters of CREATE AGGREGATE can be written in any order, not just the order illustrated above.
See Section 35.10.
CREATE AGGREGATE is a PostgreSQL language extension. The SQL standard does not provide for user-defined aggregate functions.
Please use this form to add your own comments regarding your experience with particular features of PostgreSQL, clarifications of the documentation, or hints for other users. Please note, this is not a support forum, and your IP address will be logged. If you have a question or need help, please see the faq, try a mailing list, or join us on IRC. Note that submissions containing URLs or other keywords commonly found in 'spam' comments may be silently discarded. Please contact the webmaster if you think this is happening to you in error.
Proceed to the comment form. | <urn:uuid:d15abe31-e644-4864-95eb-a9f84a19c98b> | 2.921875 | 1,711 | Documentation | Software Dev. | 38.916283 |
The outermost electrons of an atom that can be gained or lost in a chemical reaction. Valence electrons are very important in determining how an element reacts chemically with other elements.
Very weak forces that exist between molecules. The smaller the molecules, the weaker the Van der Waals forces. These forces were named after Johannes van der Waals (1837-1923), a carpenter’s son from Dutch who was trained as a physics teacher and later returned to the university to study the physical properties of the gases. Van der Waals’ research showed the existence of very weak forces between molecules, an interaction too feeble to be classified as “bonds”. Johannes van der Waals was awarded the 1910 Nobel Prize for physics. The first isolation of Van Der Waals molecules took place in the 1980s.
An oscillatory motion —a movement first in one direction and then back in the opposite direction. According to the famous physicist R.P. Feynmann “everything that living things do can be understood in terms of the jigglings and wigglings of atoms…”
Visible light coming from the sun is made up of seven different colours, which correspond to different electromagnetic waves. These colours are: red, orange, yellow, green, blue, indigo and violet. A rainbow is an arch of light comprised of all the colours of the visible spectrum in their order. We can also see the different colours of the visible light by using a prism (light analysis).
Chemical compounds that are light and can be readily vaporised but not easily dissolved in water. Many of them are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals and refrigerants inducing short or long-term adverse health effects
Εlectrical potential energy per unit charge. | <urn:uuid:1dbd75c9-0a4f-49bf-bb70-3f483606c7bc> | 3.71875 | 372 | Structured Data | Science & Tech. | 42.936877 |
> Kevin: Fox used the following characteristics to define life: cellularity,
> metabolism, reproduction, and response to external stimuli.
> Not bad. But in order to settle the issue, others will have to agree with
> you and Fox. They can also move their goalposts. Personally I believe that
> Fox's protocells are certainly make good candidates.
I cannot speak for our creationist "friends", but this is the definition you
will find in the dictionary and most biology textbooks. Even Fox's
scientific critics agree that these are basic characteristics of life; they
simply want to add other characteristics that are based on features that even
they admit did not appear until later in the history of the origin of life on
earth. In other words, they would agree that Fox's protocells are at least
partially alive (they have "protolife") compaired to modern cells. Fox is
simply arguing that his four characteristics are the most basic, fundamental
features that any protocell must have to even be proto-alive, and that the
other features some critics prefer are merely more advanced examples of the
simpler systems and structures his protocells already possess.
Kevin L. O'Brien | <urn:uuid:21d75dff-89c3-49cd-aa0f-686826421f44> | 2.6875 | 255 | Comment Section | Science & Tech. | 35.772 |
For a school project I need to find the number of chromosomes of an organism (specifically the adelie penguin, Pygoscelis adeliae). After several internet searches and a look through the encyclopedia at school, I am unable to find a definite answer to this question. Sources on the internet claim anything from 38 to 96 for diploid cells (with none of them citing a trustable study).
Is there any database that records the chromosome number for organisms?
Also, if this information is unavailable, what is the best way to estimate this value? On the Wikipedia article for number of chromosomes for various organisms, it listed the value for some birds, most of them in the 70-80 range. Is it safe then to assume that the number for penguins in general would be somewhere in this range? | <urn:uuid:f29e44d7-604a-43a1-b970-38393454094f> | 2.84375 | 168 | Q&A Forum | Science & Tech. | 44.041471 |
|- Apache Point|
|- 2.5-m Telescope|
|Details of the Data|
Before astronomers can make a map of the sky, they need a telescope. Past surveys,
such as the Palomar Sky Survey, were done with Schmidt telescopes with correcting
lenses 48 inches (1.5 m) across. To map more distant, fainter objects, Sloan
astronomers decided to build a brand new telescope with lenses 2.5 meters (100 inches)
Apache Point Observatory
The SDSS telescopes are located at
Apache Point Observatory (APO)
in Sunspot, New Mexico. The observatory is surrounded by the Lincoln National
Forest in the Sacramento Mountains, and sits on a mountain 9,200 feet above sea level,
where the atmosphere contains little water vapor and few pollutants. Because the site
is so high and so far from major cities, the night sky seen from APO is among the
darkest in the United States.
In addition to the SDSS telescopes, the APO also houses a 3.5-meter telescope and
New Mexico State University's 1.0-meter telescope.
The Main 2.5-meter Telescope
Because the SDSS telescope will make
a map of the whole sky, it must produce in-focus images over a large field of view.
Most modern telescopes, like the huge 10-meter
Keck telescopes in
Hawaii, are used to observe small patches of sky at a time. To see a large area of sky
at once, the SDSS telescope required a different and complex design.
The inside of the telescope is
dominated by two reflecting mirrors. Light reflects from the mirrors into a focusing
system that includes two corrective lenses, which minimize distortion. The diagram
at right shows how that incoming starlight strikes the 2.5-meter primary mirror,
bounces back and strikes the smaller (1.08-meter) secondary mirror, then is
reflected back through a hole in the primary mirror. The light passes through
the first correcting lens and then through the second lens on top of the camera.
The telescope can take sharply focused images from an area of three degrees,
equal to the diameter of about 30 full moons.
Although this design looks like a typical Cassegrain telescope, the mirror
surfaces are of a different shape, and the focusing system uses an additional
corrective element. The telescope's housing is also unique. Most telescopes
are kept inside domes, with only a small slit in the dome for observing.
However, this arrangement often causes heat become trapped inside the dome during
the day. When the heat is released at night, the escaping heat causes air turbulence
that blurs the telescope's images. To avoid this problem, the SDSS telescope is
completely removed from its enclosure, and carries its own wind baffle
(the metallic box around the telescope tube).
The Photometric Telescope
In addition to the main telescope, the SDSS uses this 0.5-meter Photometric Telescope to monitor subtle changes in the atmospheric temperature and pressure during the course of the survey. This information allows astronomers to calibrate an object's brightness as measured with the main telescope. | <urn:uuid:848c8ab3-c2c4-4354-89ee-8cc83038f16d> | 3.96875 | 674 | Knowledge Article | Science & Tech. | 45.391412 |
1: Earth's Climate System
How does the Earth's climate work? Topics include: the greenhouse
effect; ocean circulation; El Niño; climate and weather; climate
change; and the history of climatology.
2: Past and Future
What was the Earth's past climate like? How will it change in the new century?
Topics include: ice ages; climate cycles; the politics of climate change;
and the future of fossil
INTRO TO ASTRONOMY
How did the Universe come to be? How do astronomers know the distances to
the stars? What are comets
made of? This is a survey of the field of astronomy with a focus on applications
to geology and biology. Topics include: the Big
Bang; the solar system; observational astronomy; and extrasolar planets.
Are we humans alone in the universe?
Is there life on other planets? Explore the history of life on our own planet
and the possibility for life elsewhere. Topics include: the ingredients
of life; the origin of life on Earth; exobiology:
the science of life
beyond Earth; and the search for intelligent life in the universe.
Students can register online when they visit
the Extensions website at www.extension.ucsd.edu. Students will need
to pull down the scroll bar to select education courses. They can also call
to register at (858) 534-3400. | <urn:uuid:88db469f-b9ca-4843-b397-4f57d0e2d840> | 3.484375 | 301 | Content Listing | Science & Tech. | 49.596053 |
||It has been suggested that this article be merged with Graphene. (Discuss) Proposed since March 2012.|
Graphyne is an allotrope of carbon. Its structure is one-atom-thick planar sheets of sp and sp2-bonded carbon atoms arranged in crystal lattice. It can be seen as a lattice of benzene rings connected by acetylene bonds. Depending on the content of acetylene groups, graphyne can be considered a mixed hybridization, spn, where 1 < n < 2, and thus differs from the hybridization of graphene (considered pure sp2) and diamond (pure sp3).
The existence of graphyne has been conjectured more than 50 years ago but it has attracted attention after the discovery of fullerenes. Although not synthesized yet, periodic graphyne structures and their boron nitride analogues were shown to be stable on the basis of first-principles calculations using phonon dispersion curves and ab-initio finite temperature, quantum mechanical molecular dynamics simulations.
Graphdiyne (graphyne with diacetylene groups) has successfully been synthesized on copper substrates. Recently it has been advertised as a concurrent for graphene, due to the potential of direction-dependent Dirac cones.
Graphyne has yet to be synthesized in significant quantities for study but through the use of computer models scientists have been able to predict several properties of the substance on assumed geometries of the lattice. The proposed structures of graphyne are derived from inserting acetylene bonds in place of Carbon-Carbon single bonds in a graphene lattice. Graphyne is theorized to exist in several different geometries. This variety is due to the multiple arrangements of sp and sp2 hybridized carbon. The proposed geometries include a hexagonal lattice structure and a rectangular lattice structure. Out of the theorized structures the rectangular lattice of 6,6,12-graphyne hold the most potential for future applications.
The models for graphyne show that it has the potential for Dirac cones on its double and triple bonded carbon atoms. Due to the Dirac cones, there is a single point in the Fermi level where the conduction and valence bands meet in a linear fashion. The advantage of this scheme is that electrons behave as if they have no mass, resulting in energies that are proportional to the momentum of the electrons. Like in graphene, hexagonal graphyne has electric properties that are direction independent. However, due to the symmetry of the proposed rectangular 6,6,12-graphyne the electric properties would change along different directions in the plane of the material. This unique feature of its symmetry allows graphyne to self-dope meaning that it has two different Dirac cones lying slightly above and below the Fermi level. Graphyne samples synthesized to date have shown a melting point of 250-300°C, low reactivity in decomposition reactions with oxygen heat and light.
Future Applications
The directional dependency of 6,6,12-graphyne could allow for electrical grating on the nanoscale. This could lead to the development of faster transistors and nanoscale electronic devices.
- Heimann, R.B.; Evsvukov, S.E.; Koga, Y. (1997). "Carbon allotropes: a suggested classification scheme based on valence orbital hybridization". Carbon 35 (10–11): 1654–1658.
- Enyashin, Andrey N.; Ivanovskii, Alexander L. (2011). "Graphene Allotropes". Physica Status Solidi B 248 (8): 1879–1883. doi:10.1002/pssb.201046583.
- Balaban, AT; Rentia, CC; Ciupitu, E. (1968). Rev. Roum. Chim. 13: 231.
- Özçelik, V. Ongun; S. Ciraci (January 10, 2013). "Size Dependence in the Stabilities and Electronic Properties of α-Graphyne and Its Boron Nitride Analogue". The Journal of Physical Chemistry C. doi:10.1021/jp3111869.
- Guoxing Li; Yuliang Li; Huibiao Liu; Yanbing Guo; Yongjun Li; Daoben Zhu (2010). "Architecture of graphdiyne nanoscale films". Chemical Communications 46 (19): 3256–3258. doi:10.1039/B922733D.
- Malko, Daniel; Neiss, Christian; Viñes, Francesc; Görling, Andreas (24 February 2012). "Competition for Graphene: Graphynes with Direction-Dependent Dirac Cones". Phys. Rev. Lett. 108 (8): 086804. doi:10.1103/PhysRevLett.108.086804.
- Schirber, Michael (24 February 2012). "Focus: Graphyne May Be Better than Graphene". Physics 5 (24). doi:10.1103/Physics.5.24.
- Kim, Bog G.; Choi, Hyoung Joon (2012). "Graphyne: Hexagonal network of carbon with versatile Dirac cones". Physical Review B 86 (11): 115435. arXiv:1112.2932. doi:10.1103/PhysRevB.86.115435.
- Dumé, Belle (1 March 2012). "Could graphynes be better than graphene?". Physics World (Institute of Physics).
- Bardhan, Debjyoti (2 March 2012). "Novel new material graphyne can be a serious competitor to graphene".
- Cartwright, J. (1 March 2012). "Graphyne could be better than graphene". | <urn:uuid:90dc091a-0a09-41cd-976b-518a37f0ea09> | 2.859375 | 1,223 | Knowledge Article | Science & Tech. | 52.990443 |
Under the electron microscope, the scales of most species appear as flat plates. The base of the plate may be unornamented, or ornamented with thickened strips (cross-striate) or thin spots (punctate). In species with nearly linear scales, the scales may be solid or nearly-solid rods. In most species, scales are constant in shape and size, but in a few, variations are encountered even in the scales from a single cell. Each scale is produced separately in a specialized membrane sac, the "silica deposition vesicle" (SDV). The numerous SDVs lie just beneath the cell membrane, and are scattered around the periphery of the cell.
The centroplast consists of a trilaminate disc sandwiched between two electron-dense caps. Surrounding the centroplast is an extensive exclusion zone from which most cell organelles are absent. The axopodial axonemes (groups of microtubules that form the structural core of the axopodia) emanate from electron-dense material immediately surrounding the centroplast. It is presumed that the centroplast is the organizing center for these microtubules.
The axopodial axonemes consist of an array of numerous (ca. 20-100) cross-linked microtubules, arranged in an intricate repeating pattern of triangles and hexagons.
Return to summary information | <urn:uuid:8fb8f5b2-6681-46cb-9c16-f79302d32d17> | 3.5 | 296 | Knowledge Article | Science & Tech. | 29.005682 |
Tomorrow morning the asteroid Asteroid 2012 DA14 will pass by the earth. At its nearest approach Friday (Feb. 15, Morning of February 16 NZ time), the 150-foot-wide (45 meters) asteroid 2012 DA14 will be just 17,200 miles (27,000 kilometers) from Earth (within the orbits of geosynchronous communications, weather and navigation satellites) — the closest encounter with such a large space rock that researchers have ever known about in advance.
This brief video provides some information.
Thanks to: Science Today – Asteroid 2012 DA14
NASA TV will also run a live commentary of the flyby February 15 11 a.m. PST (2 p.m. EST) US time – 8 am NZ time.
Should we worry?
Nothing to worry about they tell us!
But here’s what worries me.
This asteroid was only discovered a short time ago (within the last year). The fact that it will pass so close indicates a reasonable chance we could actually be hit by an asteroid that size any time. One capable of destroying a major city.
There are larger asteroids out there. Some large enough to cause world-wide damage – even extinction of life.
Shouldn’t we be doing something about this possibility?
Yes, I know we are busy finding and mapping orbits of near earth objects. But what would we do if we actually found one that was on target for a direct hit? With notice of only a few month?
We should be working hard to develop the spacecraft and techniques capable of diverting such objects. And have them ready, able to do the diversion with very little notice.
I suspect we already have the technology and ideas to produce such craft.
Several years ago I was shocked at the reaction of some US space enthusiasts when the Russians announced they were putting effort into systems for diverting asteroids. They seemed to think the idea was fanciful.
Fortunately, since then the US has announced plans of their own to at least develop the ability to make manned visits to asteroids.
Surely space-faring nations should be working together to urgently develop the ability to divert near earth object? The future of our species may depend on it. | <urn:uuid:21623bc5-9f04-4062-8a9e-9387c3215647> | 2.984375 | 454 | Personal Blog | Science & Tech. | 59.395342 |
Diffusion is the chemical process when molecules from a material move from an area of high concentration (where there are lots of molecules) to an area of low concentration (where there are fewer molecules). This happens through otherwise random movement. Diffusion usually happens in a gas although it can happen in a liquid. It is possible to see diffusion happening when two liquids are mixed in a transparent container. It describes the constant movement of particles in all liquids and gases.These particles move in all directions bumping into each other. Diffusion can only work with gases and liquids. Here are some examples of diffusion:
- A sugar cube is left in a beaker of water for a while.
- The smell of ammonia spread from the front of the classroom to the back of the room.
- Fumes of perfume rises from the bottle when the top is removed.
- Food coloring dropped on the beaker causing to spread out.
One of the most important things about diffusion is that molecules tend to move from places of high concentration to places of low concentration, just by moving randomly. For example, there is more oxygen in a lung than there is oxygen in the blood so oxygen molecules will tend to move into the blood. Similarly, there is more carbon dioxide molecules in the blood than in the lung so carbon dioxide molecules will tend to move into the lung.
Diffusion can be considered to arise from probability alone - areas of high density are, due to the random movement of fluid molecules, likely to spread out within their boundary until they can do so no longer. Diffusion is also connected to Entropy. | <urn:uuid:ac1e8462-e532-4a98-b4c5-979d6d404a3b> | 4.28125 | 324 | Knowledge Article | Science & Tech. | 42.823116 |
Will NASA land a man on Mars by 2030? That is the question being raised by scientists around the nation following an announcement by the U.S. space agency that it will return to Mars in 2020 in preparation for a manned mission by 2030. In a statement released late Tuesday of last week, NASA officials announced their latest plans for the Red Planet, saying they plan to use a pair of upcoming Mars missions to further expand their knowledge in preparation for a 2030 manned mission... To continue reading, subscribe to The Space Reporter today.
|Subscribe to The Space Reporter and gain access to one of the web's largest collection of space news and analysis.|
|Already have an account? Sign in and begin reading The Space Reporter today.| | <urn:uuid:86fb47f8-6191-4bb9-8d3c-5cc716f808b2> | 2.703125 | 148 | Truncated | Science & Tech. | 62.733392 |
Conservation of Charge
When we worked out Ampères law in the case of magnetostatics, we used a certain identity:
which we often write as
That is, the rate at which the charge at a point is increasing is the negative of the divergence of the current at that point, which measures how much current is “flowing out” from that point. This may be clearer if we integrate this equation over some macroscopic region :
The rate of change of the total amount of the charge within is equal to the amount of current flowing inwards across the boundary of , so this flow of current is the only way that the charge in a region can change. This is another physical law, borne out by experiment, and we take it as another axiom.
But we might note something interesting if we couple this with Gauss’ law:
Or, to put it slightly differently:
Recall that in deriving Ampère’s law we had to assume that was divergence-free; when things are not static, the above equation shows that the composite quantity
is always divergence-free. The derivative term isn’t associated with any electric charge moving around, and yet it still behaves like a current for all intents and purposes. We call it the “displacement current”, and we add it into Ampère’s law to see how things work without the magnetostatic assumption:
This additional term is known as Maxwell’s correction to Ampère’s law. | <urn:uuid:b7e255dd-a36b-4761-b925-01254f89c905> | 3.625 | 317 | Academic Writing | Science & Tech. | 30.29787 |
The Tissint meteorite, a 58 gram sample of which is shown here, landed near Tata, Morocco in July of last year and was confirmed as martian in January. A new study shows that it and several other martian meteorites contain organic carbon of non- biological origin.
By Tyler Irving
Posted July 2012
Curiosity, NASA’s latest Mars rover, will begin its search for chemical evidence of past life on the red planet in early August. But according to a new paper in Science, the surface of Mars contains organic carbon generated by non-biological sources, which could make that search even harder.
Very rarely, material ejected from the surface of Mars by cosmic impacts can make its way to Earth in the form of meteorites. Only about 60 martian meteorites are known, eleven of which were part of the study conducted by an international team of experts, including Chris Herd of the Department of Earth and Atmospheric Sciences at the University of Alberta. Inside the martian minerals, the team found particles of carbon. “What's interesting about this stuff is that it’s not just graphite, it's organic macromolecular carbon,” says Herd. Organic carbon is present in the dust from which the solar system formed, as evidenced by primitive meteorites which can contain anything from polycyclic aromatic hydrocarbons to amino acids. Similar material would have been incorporated into Mars as it formed, stored in its interior, and could later have reached the surface by means of lava flows.
To test this theory, lead author Andrew Steele of the Carnegie Institution of Washington used confocal Raman spectroscopy, which allows for accurate determination of both the form and location of the carbon within a given meteorite’s crystal structure. In every case, the organic carbon particles were found in inclusions within igneous minerals. “The only way it could get there is if it was present in the original magma,” says Herd. “If it had been formed by some kind of biological process, you'd expect to find it associated with rust or material that formed through alteration by water, not with the igneous minerals.” Although the finding doesn’t completely rule out the possibility that Mars once harboured life, it serves as a reminder of just how hard Curiosity will have to work to prove otherwise.
Photo credit: Department of Earth and Atmospheric Sciences, University of Alberta
Write to the editor at email@example.com | <urn:uuid:c0e6b469-634c-43e7-8e10-1487cf7c4f73> | 3.71875 | 510 | Truncated | Science & Tech. | 32.318626 |
|Thick-Headed Fly - Physocephala tibialis|
Diptera Family Conopidae
Live adult flies photographed in the wild at Allegheny National Forest, Pennsylvania. Size = 10-15mm
Insects & Spiders | Flies Index | Tachinidae | Dung Flies | Bee Flies | Robber Flies
Conopids are most frequently found at flowers, feeding on nectar with their long proboscis. Conopidae is distributed in all the zoogeographic regions except for the poles and many of the Pacific islands. About 800 species are described worldwide, approximately 67 of which are found in North America.
If you've ever seen one of these flies, you'll know how the word ethereal applies to its habit. The above specimen is only about 10mm - much smaller than the individual pictured below, which is about 15mm.
|The majority of conopids are black and yellow, or black and white, and often strikingly resemble wasps, bees, or flies of the family Syrphidae, themselves notable bee mimics. The larvae of all conopids are internal parasites, most of aculeate (stinging) Hymenoptera. Adults are said to alight and deposit eggs on their flying hosts.|
Some conopids mimic vespid wasps
Potter Wasp Eumenes sp.
Flies of North America - Order Diptera. Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies can be distinguished from all other insects in that they only have one pair of normal wings. The other pair has evolved into small ball-like structures called halteres, thought to be used as stabilizing organs during flight. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
Insects & Spiders | Flies Index | Syrphidae | Bombyliidae | Robber Flies | <urn:uuid:b63399b5-b18f-42a2-97e6-186d8f7e174c> | 3.578125 | 413 | Knowledge Article | Science & Tech. | 39.782393 |
Unix I/O is performed by assigning file descriptors to files or devices, and then
using those descriptors for reading and writing. Descriptors 0, 1, and 2 are always
used for stdin, stdout and stderr respectively. Stdin defaults to the keyboard,
while stdout and stderr both default to the current terminal window.
Redirecting for the whole script
Redirecting stdout, stderr and other file descriptors for the whole script
can be done with the
> outfile < infile
- with no command, the
exec just reassigns the I/O of the current shell.
- The form n<, n> opens file descriptor n instead of the default stdin/stdout.
This can then be used with
read -u or
Explicitly opening or duplicating file descriptors
One reason to do this is to save the current
state of stdin/stdout, temporarily reassign them, then restore them.
Example Sending messages to stderr (2) instead of stdout (1)
- standard output is moved to whatever file descriptor n is currently pointing to
- standard input is moved to whatever file descriptor n is currently pointing to
- file descriptor n is opened for writing on the named file.
- file descriptor n is set to whatever file descriptor 1 is currently pointing to.
echo "Error: program failed" >&2
Echo always writes to stdout, but stdout can be temporarily reassigned to duplicate stderr (or other file
Conventionally Unix programs send error messages to stderr to keep them separated from stdout.
Input and output to open file descriptors (ksh)
Printing to file descriptors (usually more efficient than open/append/close):
-u n args
- print to file descriptor n.
- write to the pipe to a coprocess (opened by |&)
Reading from file descriptors other than stdin:
-u n var1 var2 rest
- read a line from file descriptor n, parsing by $IFS, and placing the words into
the named variables. Any left over words all go into the last variable.
- read from the pipe to a coprocess (opened by |&)
Closing file handles
For example, to indicate to another program downstream in a pipeline that no more
data will be coming. All file descriptors are closed when a script exits.
- standard input is explicitly closed
- standard output is explicitly closed
I/O redirection operators are evaluated left-to-right. This makes a difference in a
>filename 2>&1". (Many books with example scripts get this wrong)
Example: ex5 display, text
- redirect input to the temporary file formed by everything up the matching string
at the start of a line. Allows for placing file content inline in a script.
Example: duplex display, text | <urn:uuid:5c9f0593-78ea-4afd-a695-8ce65007a263> | 3.59375 | 624 | Documentation | Software Dev. | 43.308557 |
1. The angles of quadrilateral are in the ratio 3 : 5 : 9 : 13. Find all the angles of the quadrilateral.
Answer: As you know angle sum of a quadrilateral = 360°
Hence, angles are: 36°, 60°, 108°, 156°
2. If the diagonals of a parallelogram are equal, then show that it is a rectangle.
Answer: In the following parallelogram both diagonals are equal:
As all are right angles so the parallelogram is a rectangle.
3. Show that if the diagonals of a quadrilateral bisect each other at right angles, then it is a rhombus.
Answer: In the given quadrilateral ABCD diagonals AC and BD bisect each other at right angle. We have to prove that AB=BC=CD=AD
Similarly AB=BC=CD=AD can be proved which means that ABCD is a rhombus.
4. Show that the diagonals of a square are equal and bisect each other at right angles.
Answer: In the figure given above let us assume that
DO=AO (Sides opposite equal angles are equal)
Similarly AO=OB=OC can be proved
This gives the proof of diagonals of square being equal.
5. Show that if the diagonals of a quadrilateral are equal and bisect each other at right angles, then it is a square.
Answer: Using the same figure,
(Angles opposite to equal sides are equal)
So, all angles of the quadrilateral are right angles making it a square.
6. Diagonal AC of a parallelogram ABCD bisects angle A . Show that
(i) it bisects angle C also,
(ii) ABCD is a rhombus.
Answer: ABCD is a parallelogram where diagonal AC bisects angle DAB
As diagonals are intersecting at right angles so it is a rhombus
7. In parallelogram ABCD, two points P and Q are taken on diagonal BD such that DP = BQ. Show that:
With equal opposite angles and equal opposite sides it is proved that APCQ is a parallelogram
8. ABCD is a parallelogram and AP and CQ are perpendiculars from vertices A and C on diagonal BD. Show that
9. In ∆ ABC and ∆ DEF, AB = DE, AB || DE, BC = EF and BC || EF. Vertices A, B and C are joined to vertices D, E and F respectively. Show that
(i) quadrilateral ABED is a parallelogram
(ii) quadrilateral BEFC is a parallelogram
(iii) AD || CF and AD = CF
(iv) quadrilateral ACFD is a parallelogram
(v) AC = DF
In quadrilateral ABED
So, ABED is a parallelogram (opposite sides are equal and parallel)
So, BE||AD ------------ (1)
Similarly quadrilateral ACFD can be proven to be a parallelogram
So, BE||CF ------------ (2)
From equations (1) & (2)
It is proved that
Similarly AC=DF and AC||DF can be proved
10. ABCD is a trapezium in which AB || CD and AD = BC. Show that
Key Points About Quadrilaterals
1. Sum of the angles of a quadrilateral is 360°.
2. A diagonal of a parallelogram divides it into two congruent triangles.
3. In a parallelogram,
(i) opposite sides are equal
(ii) opposite angles are equal
(iii) diagonals bisect each other
4. A quadrilateral is a parallelogram, if
(i) opposite sides are equal or
(ii) opposite angles are equal or
(iii) diagonals bisect each other or
(iv) a pair of opposite sides is equal and parallel
5. Diagonals of a rectangle bisect each other and are equal and vice-versa.
6. Diagonals of a rhombus bisect each other at right angles and vice-versa.
7. Diagonals of a square bisect each other at right angles and are equal, and vice-versa.
8. The line-segment joining the mid-points of any two sides of a triangle is parallel to the third side and is half of it.
9. A line through the mid-point of a side of a triangle parallel to another side bisects the third side.
10. The quadrilateral formed by joining the mid-points of the sides of a quadrilateral, in order, is a parallelogram. | <urn:uuid:6ae4c02f-0126-4560-b095-ce8d4ffd1748> | 3.5 | 1,037 | Tutorial | Science & Tech. | 61.328406 |
beryl (bĕrˈĭl) [key], mineral, a silicate of beryllium and aluminum, Be3Al2Si6O18, extremely hard, occurring in hexagonal crystals that may be of enormous size and are usually white, yellow, green, blue, or colorless. Beryl is commonly used as a gemstone. The refractive index is low, and the stones have little or no fire. The most valued variety of beryl is emerald. An aquamarine is a blue to sea-green beryl; morganites are rose-red beryls. It is the principal raw material for the element beryllium and its compounds.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
More on beryl from Fact Monster:
See more Encyclopedia articles on: Mineralogy and Crystallography | <urn:uuid:ba896b61-cec8-4c36-9886-d32a96214110> | 3.421875 | 189 | Knowledge Article | Science & Tech. | 30.550773 |
Challenging Perimeter Problem Perimeter of rectangle covered by 9 non-overlapping squares. From 200) American Invitational Math Exam
Challenging Perimeter Problem
⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles.
- Here's an interesting problem involving perimeter from the 2000 American Invitational Mathematics Exam.
- It says, "The diagram shows a rectangle that has been dissected into 9 overlapping squares." One, two, three, four, five, six, seven, eight, nine overlapping squares.
- "Given that the width and the height of the rectangle are positive integers with greatest common divisor one...".
- So, they're talking about the width and the height of the rectangle
- The reason why they're saying "...the greatest common divisor one..." is...
- ... they're saying that they don't have a common divisor that you can divide them both by to get a more simplified ratio.
- And to think about that is we might be faced with two choices. One where maybe this side over here is... let me draw it like this...
- ... 5 and 15, but over here our greatest common divisor isn't 1. They're both divisible by 5 over here.
- So, what you'd want do is say... no, instead of 5 and 15, they need to be 1 and 3.
- Now you have the same ratio of sides, but now the greatest common divisor is 1.
- You have it in a simplified form, or the most simplified form if you divide both this height and this width by 5.
- So, that's why they're saying "...the greatest common divisor of one..."
- And then they say, "Find the perimeter of the rectangle." So, let's see what we can do here.
- I encourage you to pause this and try to do it on your own before I bumble my way through this problem.
- So, let's start at the beginning. Let's start with this square right over here, this center square. They did tell us that they're all squares.
- So let's say that the square right over here has a length (X) and a height (X). It's an (X by X) square. Let me write it so this is an (X) and that is an (X).
- So, this is an (X by X) square right over there. And then you have this square right over here. And we don't know its measurements.
- So let's say that this square right over here is (Y by Y). So it has (Y) width and it also has (Y) height.
- Now, what is this square over here? Well, this is an (X +Y) by (X + Y) square because the width of these two squares combined made the width of this larger square.
- So I'm going to... actually, this might be an easier way to write it... since they're all squares, I'm going to write the dimension of that square inside the square.
- So this is going to be an (X by X) square, kind of a non-conventional notation, but it will help us keep things a little bit neat.
- This is going to be a (Y by Y) square, so I'm not saying the area is (Y), I'm saying it's (Y by Y).
- This over here... (X + Y) is going to be each of its dimensions. It's going to be (X + Y) height and (X + Y) width.
- Then this one over here... well, if this dimension is (X + Y) and this dimension right over here is (X)...
- ... , then this whole side... or any of the sides of this square... is going to be the sum of that.
- So, (X) + (X + Y) is (2X + Y). You can imagine that I'm just labeling the left side of each of these squares.
- The left side of this square has length (Y), the left side of this one is (X), this one is (X + Y), this one is (2X + Y).
- Then we can go to this one up here. Well, if this distance right over here is (2X + Y) and this distance right over here is (X + Y)...
- ... you add them together to get the entire dimension of one side of this square.
- So it's going to be (3X + 2Y). I just added the (2X) plus the (X) and the (Y) plus the (Y) to get (3X + 2Y)...
- ... is the length of one dimension or one side of this square, and they're all the same.
- Now let's go to this next square. Well, this length is (3X + 2Y) and this length is (2X + Y), then this entire length right over here is going to be (5X + 3Y).
- (5X + 3Y) is going to be that entire length right over there.
- We can also go to this side right over here where we have this length... I'll use the same color... this length is (3X + 2Y), this is (X + Y), and this is (Y).
- So if you add (3X + 2Y) plus (X + Y) plus (Y), you get (4X + 4Y). And we can express this character's dimensions in terms of X and Y.
- This is going to be (5X + 3Y)... and then you're going to have (2X + Y)... and then you're going to have (X).
- So, you add the X's together. 5X + 2X is 7X... plus X is 8X.
- And then you add the Y's together. 3Y + Y... and you don't have a Y there... so that's going to be + 4Y. That's the dimensions of this square.
- And finally we have this square right over here. It's dimensions are going to be Y + 4X + 4Y, so that's 4X + 5Y.
- And then if we think about the dimensions of this actual rectangle over here... if we think about its height right over there,..
- ... that's going to be 5X + 3Y + 8X + 4Y. So, 5X + 8X is 13X plus 3Y + 4Y is 7Y.
- So, that's its height. We can also think about its height by going on the other side of it. Maybe this will give us some useful constraints.
- This is going to have to be the same length as this over here. And so if we add 4X + 4X we get 8X. And then if we add 4Y + 5Y we get 9Y.
- So these are going to have to be equal to each other, so that's an interesting constraint.
- So we have 13X + 7Y is going to have to equal 8X + 9Y.
- We can simplify this if you subtract 8X from both sides, you get 5X.
- And if you subtract 7Y from both sides you get 5X = 2Y. Or you could say X = 2/5Y.
- In order for these to show up as integers, we have to pick integers here, but let's see if we have any other interesting constraints...
- ... if we look at the bottom and the top of this... if this gives us any more information.
- So, if we add 5X + 3Y + 3X + 2 Y + 4X + 4Y... this top dimension... 5X + 3X is 8X + 4X is 12X.
- And then you get 3Y + 2Y + 4Y is 9Y. That's this top dimension.
- And if you go down here, you have 8X + 4X is 12X... let me do that in the same color...
- ... and then you have 4Y + 5Y is 9Y.
- So, these actually ended up to be the same in terms of X and Y, so they're not giving us any more information... no more constraints.
- Obviously, 12X + 9Y is going to be equal to 12X + 9Y.
- So, our only constraint on this problem is what we got by setting this left hand side equal to this right hand side... X needs to be equal to 2/5Y.
- So, let's just pick some numbers so we get nice integers for X and Y, and then we can figure out the perimeter.
- We want to make sure that the dimensions don't have any common divisors.
- So if we pick Y to be equal to 5, then looking at this constraint, what is X? Well then, X is 2. It's going to be 2/5 times 5. So then X is equal to 2.
- So, let's see what we get for the dimensions of this rectangle then. So, the height of this rectangle is going to be, let's see, (13 times 2) is 26 plus (7 times 5) is 35.
- So, 26 + 35 gets us... what... gets us to 61? This is equal to 61. Did I do that right? Let's see... 55 + 6 is 61.
- And when you look at its width, you have 12X which is 24. Plus 9Y... Y is 5... so, plus 45. 24 + 45 is... what... that is 69.
- And 61 and 69 do not share any common divisors other than 1. So it looks like we're done... or, we're almost done.
- We know the dimensions of the rectangle. It is a 61 by 69 rectangle. And if you want its actual perimeter, you just add them all up.
- So the perimeter here is going to be... we can have a drum roll now!... the perimeter is going to be 61 + 69 + 61 + 69....
- ... which is equal to... well, 61 + 69 is 130. That's another 130 right there. 130 + 130 is 260.
- So it actually wasn't too bad of a problem if we just started in the middle and just built up from there...
- ... and built up the dimensions in terms of the dimensions of these 2 smallest squares and then we were able to find the perimeter.
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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about the site | <urn:uuid:4ae55160-1471-49f5-afd6-16646119416f> | 3.71875 | 2,506 | Truncated | Science & Tech. | 94.605348 |
Because current is inversly proportional to power.It's basic Ohm's law.
Let me see if this will work.
I * E
P,being power is over E(voltage) and I(current).In this formula,the current and voltage are proportional,but both are inversly proportional to power.
You can use this formula to find Power by multiplying I * E.You can also use it to find the current(I) if you know the Power and (E)Voltage by dividing the E(Voltage) into the Power(watts).
Or,if you know the power and the current(I),you can find the voltage by dividing the current(I) into the Power.Hopefully the formula above helps. | <urn:uuid:38839ed5-b49d-414b-9d6a-e7850a6734e3> | 3.390625 | 160 | Q&A Forum | Science & Tech. | 63.655121 |
[The following is an exact transcript of this podcast.]
Imagine tweezers so fine that you could reach right into a cell and manipulate individual molecules. M.I.T. researchers have created such a tweezer, using beams of light. The tweezer is so precise it’s been used to determine how strong the chemical bonds are between two protein molecules in a cell. The research was published in the June 30th edition of the Proceedings of the National Academy of Sciences. It builds on work published last fall, when the same scientists demonstrated that so-called optical tweezers could pick up and move cells on a microchip. Scientists wanted to investigate protein bonds to get a better understanding of the forces that give cells structure and the ability to move around.
They used the light-beam tweezer to pin one type of protein in place. Another beam tugged at a second protein, which eventually broke completely away from the first. By knowing the energy necessary to break the bond, the scientists were in fact measuring the strength of that bond. Researchers say the tweezers can be applied to hundreds of other protein interactions that make up the cell’s architectural skeleton—potentially teasing out secrets of how cells work. | <urn:uuid:30476bf0-20b0-4759-9b40-0896e91f9ce4> | 3.78125 | 252 | Truncated | Science & Tech. | 51.839615 |
May 20, 2012,
an annular solar eclipse sweeps across east Asia, over the northern
Pacific Ocean, and then into the
southwestern United States. This is
eclipse is the first of three remarkable astronomical events of
2012, followed by the transit of Venus on June 5-6, 2012, and a total
solar eclipse (TSE) on November 13, 2012. The Annular Eclipse is
commonly known as the Ring of Fire.
An annular eclipse occurs when the moon passes directly in front of
the sun, but does not completely obscure it, leaving a ring or
"annulus" of sunlight flaring around the lunar disk. It is the first
annular eclipse to be seen from the United States in 18 years.
The moon can be seen directly in front of the sun first from the
southeast edge of China, then Japan, at its greatest at the
International Date Line in the Pacific Ocean just south of the
island chain stretching from Alaska, across the southwest corner of
Oregon, northern California, the middle half of Nevada, southwest
Utah, northern Arizona, northwest to southeast New Mexico, and right
at sunset, the southern part of the Texas panhandle.
For example, from Austin, Texas, you can observe the partial eclipse
from 7:34 pm until sunset at 8:21 pm. The point of greatest eclipse
occurs south of Kiska and Buldir in Alaska at 23:52:46 UT. It is
visible for 5 minutes and 46 seconds in this area. Be sure to not
look directly into the sun without proper protective glasses or sun | <urn:uuid:5e862871-7ce6-4f6b-95e5-a0e926c6c757> | 3.421875 | 339 | Knowledge Article | Science & Tech. | 48.750608 |
Distributive, Identity and Inverse Axioms
An Axiom is a mathematical statement that is assumed to be true.
- The Distributive Axioms are that x(y + z) = xy + xz and (y + z)x = yx + zx.
These equations are true for all numbers x, y and z.
- The Additive Identity Axiom states that a number plus zero equals that number.
x + 0 = x or 0 + x = x
- The Multiplicative Identity Axiom states that a number multiplied by 1 is that number.
x*1 = x or 1*x = x
- The Additive Inverse Axiom states that the sum of a number and the Additive Inverse of that number is zero.
Every real number has a unique additive inverse. Zero is its own additive inverse.
x + (-x) = 0
- The Multiplicative Inverse Axiom states that the product of a real number and its multiplicative inverse is 1.
Every real number has a unique multiplicative inverse. The reciprocal of a nonzero
number is the multiplicative inverse of that number. Reciprocal of x is 1/x.
x * 1/x = 1 | <urn:uuid:6b64cb7c-8fec-4003-b28b-cc32a45bed7c> | 4.09375 | 263 | Knowledge Article | Science & Tech. | 57.308092 |
Vassar college Professor John H. Long is a marine biologist, by training, and, now, a roboticist by trade. Essentially, he builds robot populations closely modeled on extinct (and living) fish, and then subjects them to simulated evolutionary pressure—to hype it up a bit, he “pits them against each other”—to learn things about why historical animals evolved as they did.
I was skeptical, at first. Seems like a cool idea, but can you really build a robot that’s enough like a real fish to draw reliable conclusions? Then I listened to this video interview, embedded above, from Vassar’s newspaper The Miscellany News.
And I’m still skeptical. But less so. John is a passionate and engaging talker, and has had a bunch of papers in Zoology and other prestigious journals with titles like “The Importance of Body Stiffness in Undulatory Propulsion,” “Swimming fundamentals: turning performance of leopard sharks (Triakis semifasciata) is predicted by body shape and postural reconfiguration,” and “Fish out of water: terrestrial jumping by fully aquatic fishes.”
As these titles hint, Dr. Long’s focus is really on biomechanics, e.g. how one body shape might confer behavioral advantages over another. Which makes it easier for me, at least, to understand how his approach could actually work:
We were interested in the evolution of structures like the backbone, for example, but we weren’t interested in the evolution of the brain. So we didn’t touch the brain. So all we did was evolve the body. So here’s a big surprise: You evolve the body, and you get smarter robots. You don’t need to touch the brain to become smarter. You can just have a “smarter body,” if you will. And the reason that’s a surprise is because, as humans, we’re so focused on our heads, and the giant size of our brain—right?—that we think this is the ultimate answer to any question about animal intelligence or human intelligence. Sure: Brains are important. But they’re not all that’s important.
Dr. Long has a book out, and will be speaking at World Maker Faire New York this Saturday at 4:30PM. Still skeptical? Come on out and hear what he has to say.
Maker Faire Project Profile
I'm a biologist and cognitive scientist at Vassar College who designs and builds simple biomimetic biorobots as models of living and extinct organisms. I then build populations of biorobots and subject those populations to evolutionary pressures to test our ideas of how animals might have evolved. I'll highlight the design process, the experiments, and what we've learned. I'm the author of "Darwin's Devices: What Evolving Robots Can Teach Us About the History of Life and the Future of Technology." (Basic Books, 2012) | <urn:uuid:c4f57cc3-30aa-42d9-ab09-17fac861d6de> | 3 | 638 | Personal Blog | Science & Tech. | 53.421464 |
A phase diagram is common way to represent the various phases of a substance and the conditions under which each phase exists. A phase diagram is a plot of pressure (P or ln P) vs temperature (T). Lines on the diagram represent conditions (T,P) under which a phase change is at equilibrium. That is, at a point on a line, it is possible for two (or three) phases to coexist at equilibrium. In other regions of the plot, only one phase exists at equilibrium.
The phase diagram for a substance is shown below. This particular substance exists in a single form as a solid. A purple dot on the phase diagram marks the current state (temperature and pressure).
The cylinder at the lower right has a movable barrier and contains a pure sample of the substance. The color of the substance indicates its phase: green for the solid phase, blue for the liquid phase, and red for the gas phase. For the liquid and gas phases, the shade of the color is related to its density.
The controls allow the user to heat or cool the sample (thereby changing the temperature) and compress or expand the sample (thereby changing the pressure). A single click on a button produces a very small change in conditions. Holding down the mouse button allows the rate of change to accelerate. | <urn:uuid:749eb92e-d280-4960-b05c-818e4c9ba7c0> | 4.09375 | 269 | Documentation | Science & Tech. | 55.092037 |
Hydrogen Sulfide (H2S) dissociation into hydrogen and sulfur has been studied in a pulsed corona discharge reactor (PCDR). Due to the high dielectric strength of pure H2S (~2.9 times higher than air), a non-thermal plasma could not be sustained in pure H2S at discharge voltages up to 30kV with our reactor geometry. Therefore, H2S was diluted with another gas with lower dielectric strength to reduce the breakdown voltage. Breakdown voltages of H2S in four balance gases (Ar, He, N2 and H2) have been measured at different H2S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H2S and the balance gas. With increasing H2S concentrations, H2S conversion initially increases, reaches a maximum and then decreases. H2S conversion and the reaction energy efficiency depend on the balance gas and the H2S inlet concentrations. H2S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gasses, such as N2 and H2. These observations can be explained by proposed reaction mechanisms of H2S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H2S into hydrogen and sulfur. | <urn:uuid:7f0f07cb-7e2e-4eab-8b62-37771225bcab> | 2.703125 | 281 | Academic Writing | Science & Tech. | 44.373514 |
|This article does not cite any references or sources. (November 2010)|
In zoology, sessility is a characteristic of some animals, such that they are not able to move about. Sessile animals are usually permanently attached to a solid substrate of some kind, such as a part of a plant, a dead tree trunk, or a rock. For example, barnacles attach themselves to the hull of a ship, but corals lay down their own substrate.
Sessile animals typically have a motile phase in their development. Sponges have a motile larval stage, which becomes sessile at maturity. In contrast, many jellyfish develop as sessile polyps early in their life cycle. In the case of the cochineal, it is in the nymph stage (also called the crawler stage) that the cochineal disperses. The juveniles move to a feeding spot and produce long wax filaments. Later they move to the edge of the cactus pad where the wind catches the wax filaments and carries the cochineals to a new host.
Clumping is a behavior in an animal, usually sessile, in which individuals of a particular species group close to one another for beneficial purposes, and can be seen in coral reefs and cochineal populations.
See also
|This biology article is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:6a7c57fa-c459-4619-95b4-e1ae3e9376e6> | 3.71875 | 295 | Knowledge Article | Science & Tech. | 41.309857 |
Brief SummaryRead full entry
M. hjorti was originally described from five badly damaged specimens from the North Atlantic, then redescribed by Rancurel (1973) from three squid from the Gulf of Guinea. The species is distinctive and widely distributed but uncertainty exists on the taxonomic status of populations in other oceans.
A Mastigoteuthis ...
- with two photophores on each eyeball.
- with very large fins (length ca 90% of ML). | <urn:uuid:9ab6b727-a43b-4458-9d9a-7d2a2c682f03> | 2.796875 | 102 | Knowledge Article | Science & Tech. | 46.811987 |
Is Space Digital? asks the cover story of this past February's Scientific American (by Michael Moyer). The subject of that article, the Fermilab's Holometer experiment (officially called Experiment E990), is a remarkable project. It is designed not to study some exotic particle or the properties of matter or energy, but to examine the fabric of space itself. The device at the heart of it is called an "interferometer". It is a 40-meter-long device that projects lasers down its length and then reflects them back. The goal is to be able to detect and analyze tiny fluctuations in the light beams as they travel along the devices arms and interfere with themselves.
The project's director is Professor Craig Hogan
of the University of Chicago's Department of Astronomy and Astrophysics. Hogan has long been involved in studying a theory of reality called "the Holographic Principle
". Simply put, the Holographic Principle describes th... okay
, there's nothing really "simple" about this.
Allow me to start again.
The Holographic Principle describes the Universe as a finite set of data stored on the two-dimensional edge of the cosmos. From that data, all the information that describes everything in existence is "projected", in the same way a three-dimensional hologram is projected from a two-dimensional surface.
That projection is us and everything around us
Don't get the wrong idea. When people hear hologram or projection, they think "illusion". As the Fermilab's FAQ
page puts it succinctly, all three spatial dimensions and everything in them are real, it's just that the Universe only needs two dimensions to store the data required to describe it all. The spatial dimensions with which we are familiar, are considered "emergent". It emerges from the two-dimensional information.
Professor Hogan and his team are looking for something called "holographic noise
". They are trying to determine if, at the finest level--"the Plank length
"--the Universe is composed of discreet, individual values, like the 1's and 0's in the binary system of a computer code.
In this interview, he explains why this is critical to testing the Holographic Principle.
The first interferometer was built over a hundred years ago. How does this experiment--and the device itself-- differ from previous ones?
Modern interferometers are much more precise because they use laser light and electronic detectors. Michelson's interferometers
used a very simple detector-- his eyes!
Our machine differs from other modern ones mainly in two respects--- it gathers data very quickly, so we can track variations on light travel time, and it correlates the outputs of two nearly-coincident but separate interferometers.
If I understand correctly, a Planck length is a trillion-trillion times smaller than a hydrogen atom. How is it possible to study anything at that scale?
We cannot see it directly, but detect its indirect effects. If a system moves randomly by a Planck length every Planck time
, then in the course of a microsecond it will move more than an attometer
, a detectable amount.
Is each Planck length just a unit of measure, like an inch, or are they actual discreet things, like a page in a book?
Prof. Hogan: A Planck length is a unit of measure. We don't yet know the detailed physics that goes with that.
The article in Scientific America is entitled "Is Space Digital?" How is that question related to the Holographic Principle?
Prof. Hogan: The holographic principle refers to a finite amount of information, which is to say, the state of things can be described by a finite string of zeros and ones.
So does that mean that if the results of the experiment have the potential to rule out an infinite Universe?
Prof. Hogan: They have the potential to rule out an infinite density of information in space. The universe itself could still go on forever, but would be a countable infinity of information.
What do we know already about how the universe uses information?
Prof. Hogan: I would say, that's physics. It's pretty rich.
Are you saying that information is "the stuff" of physics? Or "the stuff" of the Universe itself?
Prof. Hogan: It's kind of hard to tell the difference. Physics describes transformations, relationships and behaviors of the world; if you like, you can call those things transformations in the form or representation of information.
If the holometer indicates that space is digital, how might that change the way we see the world at large?
Prof. Hogan: It would be a clue that would help lead us to the underlying theory, but by no means the final answer. A lot of ideas could be ruled out if they could not account for the effect. The alternative is to say that it really is continuous, or has much more information than the holographic principle allows.
When should we expect the results and what should we look for in them?
Prof. Hogan: In a year or two, we hope to have the machine working at Planckian sensitivity. We will either detect the Planckian noise or get an upper limit that will eliminate a class of ideas for unifying space-time with the quantum. | <urn:uuid:e5b70090-fc2e-4337-9e44-24cbfd00d7cd> | 3.390625 | 1,101 | Audio Transcript | Science & Tech. | 49.576362 |
The Biodiveristy Delimma
You can start thinking about preserving biodiversity right now by exploring the biodiversity of a Florida ecosystem, the Florida sand pine scrub. The sand pine scrub ecosystem is one of Florida's most endangered ecosystems. Of course, all the native plants and animals that are adapted to and depend on the scrub are threatened too. Find out more about this special place and one particular special bird, the Florida scrub jay. It only lives in Florida's scrub ecosystem.
- Select the Florida Environments Online database. [http://purl.fcla.edu/fcla/feolc]
- Search on the term "scrub jay" in the keyword field.
- Scroll down until you see an article titled "The Florida Scrub Jay," by Raymond Fernald.
- Click on that title.
- Next to where it says "Electronic Access," click on the code that has the letters "jpg" at the end. This will open the article's table of contents.
- Click on "Title" This will open the document so that you can read it. (This may take a couple of minutes to download, just be patient.)
- When you finish reading that page, scroll down to the bottom of the page and click "next."
- Keep reading and clicking "next" until you have read the entire article.
- Take notes on the scrub jay and its ecosystem as you read the articles.
- On a separate piece of paper, write a field guide entry for the scrub jay. Look at field guide entries for otherbirds at http://www.enature.com for examples. (Don't copy the scrub jay entry; everyone will know you did!) In your field guide entry, you need to include the following things:
- description of the habitat it lives in
- what it eats
- what eats it
- its range
- what it looks like
- how it nests
- what kind of family group it has
- what kind of legal protection it has
- how big of an area a family of scrub jays needs. | <urn:uuid:63662f3c-030c-44c6-ad66-93c4e4fdc898> | 3.03125 | 439 | Tutorial | Science & Tech. | 63.757917 |
|A Sei Whale feeding near the surface.|
|Size comparison against an average human|
|Sei Whale range|
The Sei whale (Balaenoptera borealis) is a dark-gray, stream-lined baleen whale that is found worldwide except in polar waters. It swims in small pods of 3-5 whales but larger groups may form at rich feeding grounds. It has very fine grey-black baleen that traps very small particles of food. It is a rorqual whale (a large baleen whale) that is similar to Bryde's whale.
The Sei whale is also called the Sardine whale, the Pollack whale, the Coalfish whale, the Japan Finner, and Rudolphi's Rorqual. Large numbers of these whales were hunted until recently for their oil and meat. It is the fastest of the great whales and can swim at about 23 mph (20 knots) in short bursts. | <urn:uuid:91b0c07e-72e1-412e-9a92-bc45eb9d75ef> | 3.078125 | 201 | Knowledge Article | Science & Tech. | 63.545625 |
The discovery of the potential of the rocket as a weapon by the Germans during the Second World War led, -after the war ended in Europe- to establishing a programme to develop such technology in the United States. As part of this research was created in July 1945 the White Sands Proving Ground, a test site located in a remote area of southern New Mexico. As soon as September was carried out the first launch of one of the V2 rockets captured to the Nazi regime.
Later renamed White Sands Missile Range (WSMR) it has become a multi-purpose test site whose main function is to provide support to missile development programs of the United States armed forces, NASA, government agencies and the private sector.
The site has an area of 3,200 square miles, making it the largest military installation in the entire US. For much of the postwar and Cold War WSMR served as a test site for the full spectrum of missile technology: the already mentioned V2, and early models of Nike, Viking, and Lance Corporal rockets.
Another notable point located within the boundaries of the complex is the so called "Trinity Site", the place where was detonated the first atomic bomb within the ultra-secret project "Manhattan". From the standpoint of biodiversity and landscape it has a remarkable point too, because within its boundaries lies the White Sands National Monument and the San Andreas wildlife refuge. Finally, it is worth to mention that WSMR is one of the alternative landing sites for NASA's Shuttle fleet.
In the context of its primary function, WSMR has often been used to launch stratospheric balloons or as a landing site for scientific loads, carried by balloons launched from the neighborg Holloman Air Force base or other sites nearby. Being a vast and desolate spot, since the dawn of the space programe it has been chosen to carry out various tests which involved the launch of all kinds of artifacts: space probes models, anthropomorphic dummies, etc. Even some test involved the use of special balloons -coated with a metal layer that gave them more radar reflectivity- as moving targets to test new systems for monitoring and controlling missiles.
The latest references to activities with balloons there dating from 1974 with the launch of a balloon during a launch campaign for the LACATE experiment a multiple atmospheric observing study carried out by NASA and other agencies.
Balloon launched list
|Date||Hour||Flight Duration||Experiment||Payload landing place or cause of the failure|
|2/27/1957||---||---No Data---||--- No Data ---|
|3/1/1957||---||---No Data---||--- No Data ---|
|4/18/1957||---||---No Data---||--- No Data ---|
|4/20/1957||---||---No Data---||--- No Data ---|
|9/27/1957||---||ANTHROPOMORPHIC DUMMY||In Orogrande - New Mexico|
|10/8/1957||---||ANTHROPOMORPHIC DUMMY||10 miles E of Picacho, New Mexico, US, US|
|5/20/1959||1:30 local||5 h||SKY CAR (Fulgham - Kaufman - Kittinger)||NW of El Paso, Texas|
|8/21/1961||23:07 MST||6 h||INFRARED SPECTROMETER||S of Lordsburg, New Mexico, US|
|12/17/1963||2 h||DYNAMIC TEST OF BALLOON ASCENT||--- No Data ---|
|9/3/1964||2 h||CROSS CHECK OF ON-BOARD ACCELEROMETER, WSMR OPTICS & DIGITAL RADAR||--- No Data ---|
|2/13/1965||30 m||TEST FLIGHT OF VITRO CORP. BALLOON RECOVERY SYSTEM||--- No Data ---|
|2/16/1965||30 m||TEST FLIGHT OF VITRO CORP. BALLOON RECOVERY SYSTEM||--- No Data ---|
|2/18/1965||20 m||TEST FLIGHT OF VITRO CORP. BALLOON RECOVERY SYSTEM||--- No Data ---|
|3/5/1965||30 m||TEST FLIGHT OF VITRO CORP. BALLOON RECOVERY SYSTEM||--- No Data ---|
|3/9/1965||20 m||BALLOON TEST 'C' LAUNCH SYSTEM||--- No Data ---|
|9/??/1968||---||-- No Data --||--- No Data ---|
|9/11/1968||---||STRATCOM - I (Stratospheric Composition)||California, US|
|9/??/1969||N||---||-- No Data --||--- No Data ---|
|11/3/1970||11:55 mst||4 h 22 m||PROJECT ATOM||Near the New Mexico-Texas border, US|
|5/5/1974||01:00 local||~ 10 h||LACATE (Lower Atmospheric Composition and Temperature Experiment)||36 kms from the launch site.|
|10/6/1983||9 h 15 m||---No Data---||--- No Data ---|
|9/15/1988||---||ABLE III (Atmospheric Balloon Lidar Experiment)||Over White Sands Missile Range, New Mexico, US, USA| | <urn:uuid:440f0539-447d-44db-851b-0a7f1e928d93> | 3.671875 | 1,174 | Knowledge Article | Science & Tech. | 50.034684 |
Science Fair Project Encyclopedia
This article is about the type of molten rock. For other meanings of magma, see Magma (disambiguation).
Magma is molten rock often located inside a magma chamber beneath the surface of the Earth. Magma is a complex high-temperature silicate solution that is ancestral to all igneous rocks, both intrusive and extrusive. Magma exists between 650 and 1200 degrees C. Magma is under high pressure and sometimes emerges through volcanic vents in the form of flowing lava and pyroclastic ejecta. These products of a volcanic eruption usually contain dissolved gases which have never before reached the planet's surface. Magma collects in many separate magma chambers within the Earth's crust, and will have slightly different compositions in different places.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details | <urn:uuid:902fb34b-b0d1-499a-bb77-93ed7f811cf7> | 4.15625 | 190 | Knowledge Article | Science & Tech. | 36.587911 |
Graphene teeth tattoos could detect bacteria,
help save lives
You want to get a tattoo where? On your
Yes, it’s true, but not quite the
tattoo you were thinking of!
Tiny teeth tattoos are being fashioned to detect
harmful bacteria in the human body and diagnose illnesses.
Researchers at Princeton University, led by
Michael McAlpine, have been developing this high-tech medical
Here’s how it works. The sensing
device is composed of graphene and silk. These two components
possess key qualities that are vital to the device’s
performance. Aside from their strength and flexibility, silk has
been known for its mechanical properties and graphene for its
ability to conduct electricity.
This silk and graphene amalgamation then comes
in contact with interdigitated electrodes and is finalized with a
coil antenna. When applied to a tooth, the silk will dissolve,
leaving just the sensing device.
The device, which has already been tested on
cows’ teeth, is composed of antimicrobial peptides and
resonant coils that eliminate the need for a power supply. When
bacteria attaches to the peptides, the graphene receives a small
electric current as a result of the electrical charges in bacterial
The gadget contains a parallel resonant circuit
that has an inductor and capacitor. These two components switch the
store of energy back and forth between them which allows for
During their testing, the team kept in mind S.
aureus, or staph infection, the common, and potentially fatal,
bacteria that plagues hospitals. In order to show how the sensor
could be used to detect antibiotic-resistant bacteria,
McAlpine’s team lined an intravenous bag with the
nanosensors and exposed it to bacterial cells. They noted the
change in resistance of the sensor as the cells built up over 30
These teeth tattoos open the door to quicker
response time of infection detection, hospital sanitation
monitoring, and food safety analysis. ■ | <urn:uuid:53488a06-8214-44df-9dc3-b23a761e6320> | 3.515625 | 431 | Truncated | Science & Tech. | 35.774923 |
A distinction can be made between multicell clusters and multicell lines or squall-lines. The latter form when convection is triggered by upward motions along some type of boundary: for example, a cold front or a convergence line. The storms that form along a boundary will likely become organized along the boundary as well. Storms often become linearly organized when their outflows merge and a large, deep cold pool forms. In that case one single boundary can form, along which new convective cells are triggered.
The greatest threat of well-organized squall-lines is posed by straight-line winds. Research has shown that the most severe winds are produced by systems that occur in environments of either
strong vertical wind shear (more than 10 m/s in the 0-2 km layer or 20 m/s or more in the 0-6 layer), or
somewhat weaker shear, but very high CAPE (more than 2500 J/kg MUCAPE)
Note that environments of very low CAPE (a few 100's of J/kg) and very strong low-level shear occasionally produce those systems as well. Their characteristics are not yet well-understood. The other extreme, CAPE > 2500 J/kg, is quite rare in Europe. If there is no pre-existing boundary or front, a high coverage of convection is necessary to create a strong cold pool, the leading edge of which can function as the boundary that triggers new cells.
Squall-lines that produce strong winds usually consist of one or more bow-echoes (figs. 1.9 and 1.10). Bow echoes are typically 20-120 km long bow-shaped of convective systems that can produce long swaths of damaging winds. As bow-echoes mature, they typically develop two vortices at the northern and southernmost edges.
A long squall line can include several bow echoes (bowing segments). In that case, the system may be called a line echo wave pattern. In environments of high wind shear, the leading edge of squall-lines may be formed by many (very) small bows as in fig. 1.11. Intense windstorms caused by convective storms (usually bow-echo storms) that affect an area of more than 400 km in length are called derechos. These are essentially families of downburst clusters. They have been documented to occur in the U.S., Canada, Germany and Finland and other countries (Johns and Hirt,1987; Gatzen, 2004; Punkka and Teittinen, 2004).
A cross-section of a typical squall-line is drawn in fig. 1.12. Characteristic of such a system are two distinct system-relative flows: a flow entering the system from ahead that rises to the back (the front-to-rear flow) and a so-called rear inflow jet that enters the system from behind at mid-levels. In the most intense systems, the rear inflow jet remains at mid-levels until just behind the leading convective line of the system, where it descends to the surface and can cause damaging winds.
Horizontal radar images of linear MCS's, such as those depicted in fig. 1.10., often show a leading line of vertical convection followed by an area of somewhat lighter rain and then a large zone of moderate or heavy rain. This stratiform precipitation zone typically develops as the squall line matures and old convective cells are left behind the growing cells along the gust front. | <urn:uuid:6fb018d6-206e-4fac-b294-01001294ec49> | 4.15625 | 732 | Knowledge Article | Science & Tech. | 60.163751 |
March 20, 2012
Since the explosion on the BP Deepwater Horizon drilling rig in the Gulf of Mexico on April 20, 2010, scientists have been working to understand the impact that this disaster has had on the environment. For months, crude oil gushed into the water at a rate of approximately 53,000 barrels per day before the well was capped on July 15, 2010. A new study confirms that oil from the Macondo well made it into the ocean’s food chain through the tiniest of organisms, zooplankton.
Tiny drifting animals in the ocean, zooplankton are useful to track oil-derived pollution. They serve as food for baby fish and shrimp and act as conduits for the movement of oil contamination and pollutants into the food chain. The study confirms that not only did oil affect the ecosystem in the Gulf during the blowout, but it was still entering the food web after the well was capped.
Oil, which is a complex mixture of hydrocarbons and other chemicals, contains polycyclic aromatic hydrocarbons (PAHs), which can be used to fingerprint oil and determine its provenance. The researchers were able to identify the signature unique to the Deep Water Horizon well in the Gulf of Mexico.
This article was posted: Tuesday, March 20, 2012 at 1:40 pm | <urn:uuid:fc2aabac-4173-4a8e-ab59-dc9b4dd62008> | 3.78125 | 274 | Truncated | Science & Tech. | 47.139991 |
Actually, along with gravitational time dilation, there is also gravitational length contraction. According to the 'further from sun' observer, the closer observer's rulers are slightly short, rather than long.
Be that as it may, there is straightforward way the two can observers agree on their speed relative to the milky way center. Suppose each adopts as their distance standard (converting other ways of measuring distance to far away object to match this standard) c times light round trip time to object as they measure it. Then the closer to sun observer thinks the MW center is closer (less time for the round trip). They then figure a smaller circumference for the orbit. They divide the smaller circumference by the shorter time, and come up with the same speed as the 'further from sun' observer. | <urn:uuid:04ed5fa4-491c-4c94-8490-ff9bb6bfdf76> | 3.015625 | 162 | Q&A Forum | Science & Tech. | 48.14 |
Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs).
Tools And Utilities
This message was edited by jason at 2004-12-5 1:47:33
Can someone explain a small point for me please. In the old days we were taught to place class declarations in the .h file and the class...
"Special Edition Using Visual C++.NET" is the best;
: I am attempting to learn how to write windows applications using Visual C++.net standard, does anyone know of any books that explain how to do...
I am attempting to learn how to write windows applications using Visual C++.net standard, does anyone know of any books that explain how to do this clearly?
Look on the compiler's CD and see if there is a samples directory. There should be several example programs that show how to write a windows program. cout does not work with windows. You have to...
Get Visual C++.NET standard its $100 just as much as visual C++ 6.0 and it has an updated version of MFC for creating windows apps, and who knows? Maybe one day you will want to start messing around... | <urn:uuid:d26ccdb5-c322-4710-bab6-10ed717610fd> | 3.078125 | 260 | Comment Section | Software Dev. | 78.510819 |
by Staff Writers
Zurich, Switzerland (SPX) Apr 26, 2012
Ammonites changed their reproductive strategy from initially few and large offspring to numerous and small hatchlings. Thanks to their many offspring, they survived three mass extinctions, a research team headed by paleontologists from the University of Zurich has discovered.
For 300 million years, they were the ultimate survivors. They successfully negotiated three mass extinctions, only to die out eventually at the end of the Cretaceous along with the dinosaurs: Ammonoids, or ammonites as they are also known, were marine cephalopods believed to be related to today's squid and nautiloids.
Ammonoids changed their reproductive strategy early on in the course of evolution. However, what was once a successful initial strategy may well have proved to be a fatal boomerang at the end of the Cretaceous, as an international team of researchers headed by paleontologists from the University of Zurich demonstrate in a study recently published in the science journal "Evolution".
Embryos already had coiled shells
The selection pressure in favor of more tightly coiled shells is believed to have sprung from the ammonoids' natural predators. As the scientists have now discovered, the shell change also affected the ammonoid embryos.
In the oldest ammonoids, the embryonic shells were considerably bigger and coiled less tightly than in later forms," explains Kenneth De Baets, a paleontologist at the University of Zurich, summing up the latest findings.
Smaller hatchlings, more offspring
In parallel, the shell size of fully grown animals increased and, on the whole, the animals became increasingly bigger. Based on this, the researchers deduced that the number of offspring in ammonoids rocketed during the Devonian Period.
his is confirmed by discoveries of substantial clusters of fossilized embryonic shells at the end of the Devonian Period and more recent deposits.
"The large number of offspring could have been the key to the rapid proliferation of the ammonoids in the aftermath of each mass extinction," De Baets suspects. His hypothesis is supported by the fact that precisely the groups with smaller, loosely coiled embryonic shells and proportionately fewer offspring died out in certain Devonian extinction events.
Nevertheless, the once successful reproductive strategy of many offspring appears to have turned against them at the end of the Cretaceous Period: The ammonoids died out. Only nautiloids have survived until today: They are characterized by large young and a small number of offspring. Exactly how this circumstance had a positive impact upon the survival of the nautiloids is unknown.
All that is clear, according to De Baets, is that nautiloids are extremely vulnerable with their reproductive strategy nowadays in view of overfishing.
Literature: Kenneth De Baets, Christian Klug, Dieter Korn, Neil H. Landmann. Early evolutionary trends in ammonoid embryonic development. Evolution, International Journal of Organic Evolution. 14 February, 2012. doi: 10.1111/j.1558-5646.2011.01567.x
University of Zurich
Life Beyond Earth
Lands Beyond Beyond - extra solar planets - news and science
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Finding ET may require giant robotic leap
University Park PA (SPX) Apr 20, 2012
Autonomous, self-replicating robots - exobots - are the way to explore the universe, find and identify extraterrestrial life and perhaps clean up space debris in the process, according to a Penn State engineer, who notes that the search for extraterrestrial intelligence - SETI - is in its 50th year. "The basic premise is that human space exploration must be highly efficient, cost effective ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement| | <urn:uuid:fe8189e1-42b0-4951-b668-e28fbfdb1a1a> | 3.546875 | 899 | Truncated | Science & Tech. | 31.857927 |
Narrator: This is Science Today. Oceanographers at the University of California's Scripps Institution of Oceanography have developed a new way to measure large-scale ocean temperatures. Peter Worcester says they're using sound transmissions to measure temperature changes over a 3,000 mile span.
Worcester: It takes about an hour for the sound to go that distance. So on this one measurement you get an average temperature and you can do it again a few minutes later, a day later, so you can get these rapid and repeated measurements of average temperature over very large areas.
Narrator: These acoustic measurements compliment current satellite techniques and may someday help scientists generate climate maps of the ocean, similar to those of the atmosphere.
Worcester: I think when we can do that, it's likely to really revolutionize our ability to understand how the atmosphere in the ocean interact to determine the long term changes from season to season, longer term climate changes. To really see how these two complicated systems work together to determine our weather and climate.
Narrator: For Science Today, I'm Larissa Branin. | <urn:uuid:d4070cda-f157-47e4-b725-a184eaa3bb30> | 3.6875 | 225 | Audio Transcript | Science & Tech. | 24.545165 |
This artist's illustration shows an enormous halo of hot gas (in blue) around the Milky Way galaxy. Also shown, to the lower left of the Milky Way, are the Small and Large Magellanic Clouds, two small neighboring galaxies (roll your mouse over the image for labels). The halo of gas is shown with a radius of about 300,000 light years, although it may extend significantly further.
Data from NASA's Chandra X-ray Observatory was used to estimate that the mass of the halo is comparable to the mass of all the stars in the Milky Way galaxy. If the size and mass of this gas halo is confirmed, it could be the solution to the "missing-baryon" problem for the Galaxy.
In a recent study, a team of five astronomers used data from Chandra, ESA's XMM-Newton, and Japan's Suzaku satellite to set limits on the temperature, extent and mass of the hot gas halo. Chandra observed eight bright X-ray sources located far beyond the Galaxy at distances of hundreds of millions of light years. The data revealed that X-rays from these distant sources are selectively absorbed by oxygen ions in the vicinity of the Galaxy. The nature of the absorption allowed the scientists to determine that the temperature of the absorbing halo is between 1 million and 2.5 million Kelvins.
Other studies have shown that the Milky Way and other galaxies are embedded in warm gas, with temperatures between 100,000 and one million degrees, and there have been indications that a hotter component with a temperature greater than a million degrees is also present. This new research provides evidence that the mass in the hot gas halo enveloping the Milky Way is much greater than that of the warm gas. | <urn:uuid:3153011a-6a6d-4ca5-a71e-02a33c21721a> | 3.828125 | 355 | Knowledge Article | Science & Tech. | 47.228 |
Delcourt, R., de Azevedo, S. A. K., Grillo, O. N., and F. O. Deantoni. 2012. Biomechanical comments about Triassic dinosaurs from Brazil. Papáis Avulsos de Zoologia 52:341-347.
Abstract - Triassic dinosaurs of Brazil are found in Santa Maria and Caturrita formations, Rio Grande do Sul state, Brazil. There are three species known from the Santa Maria Formation (Staurikosaurus pricei, Saturnalia tupiniquim and Pampadromaeus barberenai), and two from Caturrita Formation (Guaibasaurus candelariensis and Unaysaurus tolentinoi). These dinosaur materials are, for the most part, well preserved and allow for descriptions of musculature and biomechanical studies. The lateral rotation of the Saturnalia femur is corroborated through calculations of muscle moment arms. The enhanced supracetabular crest of Saturnalia, Guaibasaurus, Staurikosaurus, Herrerasaurus ischigualastensis, Efraasia minor and Chormogisaurus [sic] novasi suggests that basal dinosaurs may have maintained an inclination of the trunk at least 20° on the horizontal axis. The pectoral girdle articulation of basal sauropodomorphs (Saturnalia and Unaysaurus) was established using a new method, the Clavicular Ring, and the scapular blade remains near 60° on the horizontal axis. This is a plesiomorphic condition among sauropodomorphs and is also seen in the articulated plateosauridae Seitaad ruessi. The Brazilian basal dinosaurs were lightweight with a body mass estimated around 18.5 kg for Staurikosaurus, 6.5 kg for Saturnalia, and 17 kg for Guaibasaurus. Pampadromaeus probably weighed 2.5 kg, but measures of its femur are necessary to confirm this hypothesis. The Triassic dinosaurs from Brazil were diversified but shared some functional aspects that were important in an evolutionary context.
Oversharing and zero point energy wands: pseudoscience in the NY Times
42 minutes ago in The Culture of Chemistry | <urn:uuid:f4c0aa72-a274-4bae-b0ad-0ade837651c7> | 2.984375 | 470 | Academic Writing | Science & Tech. | 25.62153 |