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science 11

New translation, the Magna Carta

article archives at abelard's news and comment zonescience archives
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III-2004: 02 02-2 03 09 18 22 28
science and technology 11 

where on earth is mars? three GoldenYak (tm) award

“It is the only place on Earth that is, as far as anyone has been able to tell, devoid of life. The most inhospitable environments - boiling undersea thermal vents, acidic hot springs, superbriny seas, even pools of nuclear waste - all, amazingly, harbor some living thing. But not here. No one knows why. That's why McKay's team has come: This killing turf, this parched soil, is Earth's best proxy for Mars.”

badge for nasa atacama mission

Life in the Atacama 2003

“Robotic field investigation will bring new scientific understanding of the Atacama as a habitat for life with distinct analogies to Mars. Our goal is to make genuine discoveries about the limits of life on Earth and to generate knowledge about life in extreme environments that can be applied to future planetary missions. To conduct this investigation we will develop Robotic Astrobiology.

“Field investigation over three years will use a rover to make transects of the Atacama with instruments to detect microorganisms and chlorophyll-based life forms and to characterize habitats. The rover will integrate panoramic imagers, microscopic imagers, spectrometers, as well as mechanisms for shallow subsurface access.”

This second link also lists and describes field experiments, and provides links to field reports.

related material
atacama like mars

the web address for this article is


related material
atacama like mars




what is dark energy? what is dark matter?

“Gravity is losing some unknown battle, cosmologists admit. They theorize that about 70 percent of the universe is made up of dark energy, while most of the rest is another mysterious thing called dark matter and only a small fraction is real matter like stars, planets and living entities.”

“ There are two initial questions scientists are trying to answer: What is the strength of dark energy today, and does it grow or decay with time?

“The new data show that if the repulsive force is changing, "it is not changing very rapidly," Riess said.

“There is a lot of work ahead.

“ "Determining these two properties still leaves us very, very far from understanding what dark energy is," said Mario Livio, a theorist who heads the science division at the STScI. But until these first two parameters are determined, a fundamental understanding of the cosmos will remain elusive. It remains possible, for example, that our understanding of gravity "is completely lacking," Livio said.”

The issue of keeping the Hubble space telescope in action —a quick, shallow summary.

the web address for this article is


einstein helps find far-off galaxy—13 billion light years distant

image credit: Jon Lomberg/W. M. Keck Observatory

image credit: Jon Lomberg/W. M. Keck Observatory

“Even using the clarity and resolving power of the Hubble Space Telescope to first detect the galaxy, then the light-gathering power of the 10-meter Keck telescopes atop Hawaii's Mauna Kea to study it in more detail, neither could have done the job without help from Abell 2218. This is the designation given to a cluster of galaxies whose combined gravity acted as a lens to magnify the young galaxy's image and brighten it some 25 times.”

This galaxy is, as yet, the most distant ever detected.

Note: Einstein predicted gravitational lensing in his Genaral Theory of Relativity, saying that massive objects would deflect rays of light passing close to them. This effect works with objects such as our sun and with distant galaxies, where a foreground galaxy distorts the light of another, more distant, galaxy in appropriate alignment.

This site gives an understandable explication.

Here is a picture of galaxy cluster Abell 2218.

the web address for this article is


planning ahead—by woodpeckers

“A new study in the journal Condor by the New York-based Wildlife Conservation Society (WCS) and Arkansas State University suggests that a woodpecker’s beak is a virtual petri dish of fungal spores that play a key role in the decay of dead trees, or snags.“

the standing part of a dead tree

the web address for this article is


matroshka (russian doll) to work in space

“Those who spend long periods in space may risk health problems such as cancer through exposure to [cosmic ray] radiation. During a spacewalk, an astronaut is hit by about 27 times as many cosmic particles than a person on Earth.”

“Matroshka, which arrived safely at the space station last week, is expected to spend a year strapped to the outside of the station's Russian Zvezda module starting on 15 March. During that time, Matroshka will receive three times more radiation than a professional radiation worker's annual dose.”

“The doll is coated with a carbon-fibre covering that blocks ultraviolet radiation and deflects space debris, much as a space suit protects a live astronaut. And it has strategically placed radiation sensors to measure cosmic-ray doses to the stomach, lungs, kidneys, colon and eyes. It's because of all these layers that the mannequin is named after the famous hollow Russian dolls that open up to reveal ever-smaller versions of themselves inside.”

the web address for this article is


on the second law of thermodynamics

This is a nice item on the second law of thermodynamics, well worth a read.

Note: the word order/disorder is not well defined in the article. The concept is difficult. For instance, in information theory, the most dispersed situations contain the least order, and therefore require the most information to describe them. Whereas what is being referred to in the article as the most ordered systems are those that require the least information for description.

Thus information (requirement) increases with entropy.

the web address for this article is


more mars

first Mars image from Opportunity

mars postcard to send to friends?
First Mars pictures from the NASA rover, Opportunity.

rover footprints on Mars ringed in yellow
(cropped from ‘small’ image)

‘medium’ image, big enough for scrolling, with clear definition of the prints.

And what of the first recent NASA rover, Spirit?

“NASA says that rover [Spirit] is on the mend after a serious software problem cut off what had been a steady flow of pictures and data. Spirit could resume normal operations in two to three weeks.”

And of Beagle 2?

“Beagle failed to send back its planned “all's well” greeting — a few notes composed by the rock band Blur — on Christmas day, and has not been heard from since.”

water and CO2 found

“Mars Express, [who transported Beagle 2 to Mars] which reaches its final orbit this week, used a combination of camera images and data from an infrared spectrometer to reveal both frozen water and frozen carbon dioxide at the southern pole.

“More analysis using a high-resolution instrument, a planetary fourier spectrometer, confirmed these findings.”

Summary page of current Mars missions, together with small images and write-ups.

related material
human exploration of the universe grows ever more serious
mars exploration rover mission with chart of landing sites and Mars data
Mars Express

the web address for this article is


related material

human exploration of the universe grows ever more serious

mars exploration rover mission with chart of landing sites and Mars data

Mars Express


“trichromatic vision evolved twice, and linked to reduced sense of smell”

“....Thus, full trichromatic vision evolved twice in primates—once in the common ancestor of apes and Old World monkeys, about 23 million years ago, and once in the howler monkey lineage, about 7 - 16 million years ago. The evolution of color vision, the authors propose, coincided with a growing complement of OR pseudogenes and a deterioration of the sense of smell. Gilad et al. suggest that investigating the types of visual cues required for finding food may shed light on the nature of this connection.”

the web address for this article is


opals and beetles

“The study of a weevil with an opal-like shell from the dimly-lit tropical forests of northeastern Queensland, Australia, may enable humans to more easily manufacture synthetic versions of the gem.”

“ The inner structure is made up of closely packed, tiny, hexagonal spheres.”

“ ... several other species of beetles with the opal structure, ranging from bright red to violet...”

the web address for this article is


atacama like mars

“The Atacama is the only place on Earth (from which) I've taken soil samples to grow microorganisms back at the lab and nothing whatsoever grew," said Fred A. Rainey, an associate professor in biological sciences at LSU, who is a co-author of the study and an expert on microorganisms in extreme environments. "Normally, when you take a soil sample from any environment and you plate it on nutrient media, you see many different
bacterial colonies growing there after a few days. But, in the case of the soils collected in some areas of the core region of the Atacama Desert, no or very few bacterial colonies appear, even after 20 days of incubation.”

Recommended scan.

the web address for this article is


hogs and humans confused....

“Pigs grown from fetuses into which human stem cells were injected have surprised scientists by having cells in which the DNA from the two species is mixed at the most intimate level.”

“ Previous laboratory work has shown that while PERVs in pig cells cannot infect human cells, those in hybrid cells can. The discovery therefore suggests a serious potential problem for xenotransplantation.

“Perhaps HIV managed to jump from primates to humans through infected blood from a bite, which allowed the stem cells from the two species to fuse," Platt told New Scientist. "When the genes recombined, perhaps the virus was reawakened.”

the web address for this article is


where we are—in the universe

image credit:

“We have produced a new conformal map of the universe illustrating recent discoveries, ranging from Kuiper belt objects in the Solar system, to the galaxies and quasars from the Sloan Digital Sky Survey. This map projection, based on the logarithm map of the complex plane, preserves shapes locally, and yet is able to display the entire range of astronomical scales from the Earth's neighborhood to the cosmic microwave background. The conformal nature of the projection, preserving shapes locally, may be of particular use for analyzing large scale structure. Prominent in the map is a Sloan Great Wall of galaxies 1.37 billion light years long, 80% longer than the Great Wall discovered by Geller and Huchra and therefore the largest observed structure in the universe.”

The complete map, and various sheets focussing on regions such as our solar system, are available from here.

A general background article is available from the NYT (nominal login may be required).

the web address for this article is


how to skip a stone on water—38 skips to top

“To achieve the maximum number of rebounds, the angle between a spinning stone and the water should be about 20 degrees, advises Clanet: "This is the magic angle."

“Spin, speed and shape are also important. A stone is more likely to rebound if it is rotating, they found. This is because spin stabilises the object and prevents it from falling into the water.

“Speedy stones are more likely to bounce than sluggish ones.....”

the web address for this article is


human exploration of the universe grows ever more serious

marker at news

Cassini-Huygens [due at Saturn in July 2004]
should provide an unprecedented close-up of the ringed planet, which is made mostly of gas and has an average density less than that of water. Saturns' rings are made up of lumps of ice and rock - some as small as dust and some huge boulders - the debris from shattered comets, planetary satellites and asteroids.”

The Cassini-Huygens probe was launched on 16 October 1997. For more information, visit the Cassini-Huygens mission home page at NASA.


marker at news

comet updated
“Having weathered its out-of-this-world sandblasting by cometary particles hurtling toward it at about six times the speed of a rifle bullet, NASA's Stardust spacecraft begins its two-year, 1.14 billion kilometer (708 million mile) trek back to its planet of origin.”

Running the gauntlet of a comet’s coma [tail], snatching samples from the tail of one of the universe’s ‘free spirits. Travelling about 15 times the distance from the Earth to the sun by the end of its return trip, this is the first time one of our messengers has been sent on such an amazing adventure. We trust it will continue to fair well and come home.

“ Stardust scooped up these cometary particles, impacting at 6.1 kilometers per second (3.8 miles per second), for almost instantaneous analysis from onboard instruments and stored other particles for later, in-depth analysis, here on Earth. Along with this cosmic taste testing, the spacecraft also took some remarkable images of comet Wild 2's five-kilometer wide (3.1- mile wide) nucleus.”

marker at news

Team Stardust, NASA's first dedicated sample return mission to a comet, passed a huge milestone today by successfully navigating through the particle and gas-laden coma around comet Wild 2 (pronounced "Vilt-2"). During the hazardous traverse, the spacecraft flew within 240 kilometers (149 miles) of the comet, catching samples of comet particles and scoring detailed pictures of Wild 2's pockmarked surface. ”

Stardust has traveled about 3.22 billion kilometers (2 billion miles) since its launch on February 7, 1999.”


marker at news

mars rovers
After Mars Express and its ill-fated lander Beagle2,
Spirit, the first of two Mars Rovers,
is landing on Mars today, 3 January at about 13.30 UT.

The second Mars Rover, Opportunity, will be landing on 24 January 2004.

The Mars Rover Mission homepage is here, while a detailed information source on these two missions, including background is in the Landing Press Pack (46-page PDF).


marker at news

potential for life
potential for life in the home galaxy

“Dr Lineweaver estimated that 10 per cent of the Milky Way's stars were in the habitable zone, suggesting about 30 billion could support complex life.

“Their finding that the Sun is younger than 75 per cent of stars in the zone may help answer one question: Are we the smartest or stupidest things in the universe?

“ "We may be young," Dr Lineweaver said. "Seventy-five per cent of the complex life in the galaxy have been around longer than we have." ”

Picture of galaxy at item.

related material
mars exploration rover mission with chart of landing sites and Mars data
Mars Express

the web address for this article is


related material

mars exploration rover mission with chart of landing sites and Mars data

Mars Express

earth on time—again

“Timekeepers at the National Institute of Standards and Technology (NIST) note that they have not had to insert an extra second (called a leap second) into their time scale for five years. Why? Because the rate of the Earth’s rotation has sped up since 1999.”

“Tom O’Brian, a physicist and chief of NIST’s Time and Frequency Division in Boulder, Colo., suggests changes in motion of the Earth’s core, the effect of ocean tides and weather, and changes in the shape of the Earth may all be affecting the spin of Mother Earth. In general, he notes, the long-term trend has been for the Earth’s rotation to slow down, but not in the last five years.”

marker at news and comment

A leap second is a second added to Coordinated Universal Time (UTC) to make it agree with astronomical time to within 0.9 second. UTC is an atomic time scale, based on the performance of atomic clocks. Astronomical time is based on the rate of rotation of the earth. Since atomic clocks are more stable than the rate at which the earth rotates, leap seconds are needed to keep the two time scales in agreement.

“The first leap second was added on June 30, 1972, and they occur at a rate of slightly less than one per year, on average. Although it is possible to have a negative leap second (a second removed from UTC), so far, all leap seconds have been positive (a second has been added to UTC). Based on what we know about the earth's rotation, it is unlikely that we will ever have a negative leap second.”

Leap seconds affect much in the global village, including communication, navigation and air traffic control systems and the computers linking global financial markets.

A table of the leap-second changes can be seen here.

the web address for this article is


rat detectives—faster than humans, but are they accurate enough?

“Giant rats in Sub-Saharan Africa are being trained to sniff out tuberculosis in humans. The rats have already been successfully used to detect land mines by their odour.

“Preliminary tests suggest the rats could test as many as 150 saliva samples for TB in just 30 minutes. By contrast, human technicians using a microscope can test only 20 samples a day. The World Bank has now provided $165,000 for a full study of the rats' diagnostic potential.”

related material
cause, chance and Bayesian statistics

the web address for this article is


related material
cause, chance and Bayesian statistics


shooting round corners—bendy gun

“The front section can be bent up to 60° to the left or the right, allowing a soldier to shoot around a wall or door without exposing any part of themselves to enemy fire.”

Picture at link.

the web address for this article is


uav advance—computer-piloted helicopter: non-gps inertial and visual con

“This is the first UAV to use computerised vision with all its equipment on board," he says. "It can maintain its position without using GPS, which hasn't been done before.”

“ Corke says that new sensing equipment developed for the Mantis opens up a large number of applications for rescue and surveillance work. This could include fleets of helicopters inspecting sites as part of bushfire-prevention strategies, or searching the ocean to speed up sea-rescue efforts.”

unmanned aerial vehicle (flying drones).

the web address for this article is


advance notice: streaming live mars images

“ESA PR 82-2003. Launched on 2 June 2003, after a six-month cruise at an average speed of about 10 kilometres per second and covering a distance of about 400 million kilometres, ESA's Mars Express will arrive at Mars on Christmas Day.

“After a very complicated and challenging series of operations during the night of 24/25 December 2003, the probe will be injected into an elliptical orbit near the poles of the Red Planet, while the Beagle 2 lander – released from the mother craft six days earlier – is expected to touchdown on the surface of Mars. ”

“The highlights of the night will also be webcast over the internet at”
[Note: this link is not yet operational.]

The purpose of this mission:

Mars Express promises to provide the most detailed view yet of the Red Planet. Its lander, called Beagle 2, was released on Friday and is scheduled to land on Mars on Christmas Eve (EST). It will scour the surface for water and life forms, and those images will be streamed to the ESA site ( ). The probe, built for the ESA by a consortium of European companies, is equipped with scientific instruments that will be used to perform remote-sensing experiments designed to shed new light on Mars' structure, geology, and atmosphere, as well as its potential for supporting life.”

the web address for this article is


new spitzer drinks in images from space (NASA press release)

“A new window to the universe has opened with today's release of the first dazzling images from NASA's newly named Spitzer Space Telescope, formerly known as the Space Infrared Telescope Facility.”

Link to gallery of images

Disc of planet-forming debris encircling Fomalhaut, a ‘nearby’ star.

Image: fomalhaut-150.jpg, courtesy of JET Propulsion Laboratory, California Institute of Technology

Spitzer will be the final mission in NASA's Great Observatories Program - a family of four orbiting observatories, each observing the Universe in a different kind of light (visible, gamma rays, X-rays, and infrared). Other missions in this program include the Hubble Space Telescope (HST), Compton Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory(CXO). Spitzer is also a part of NASA's Astronomical Search for Origins Program, designed to provide information which will help us understand our cosmic roots, and how galaxies, stars and planets develop and form.”

the web address for this article is


advanced technology lens for 260° view without moving

“Until now, taking a 360° panorama with a normal lens has required taking multiple shots while rotating the camera slowly and then combining (“stitching”) those shots together to form the panorama. In contrast, the 360° full-circle lens allows the full 360° surroundings of the camera to be imaged at the same time with a single lens.”

The lens resolution is only 380k pixel so far, so the resulting picture is highly pixelated

[lead from Limbic]

the web address for this article is


bacteria to clean galician national park
Reports sourced from El Correo Gallego and El Mundo [both reports in Spanish]

This week, work starts to clean 10,000 square metres of rocky zones polluted by the oil spilled from the Prestige tanker in November, 2002.

A product called S-200 Custom-Blend, made by the Spanish company IEP Europe SL, has been chosen by National Park authorities to enable bacteria to ‘biologically’ clean rocks, sand and water in the Atlantic Islands National Park (Pontevedra).

The director of IEP Europe, Santiago Ramas, explained that S-200 does not add new alien bacteria to the environment, but provides bacterial nutrients to species that already exist in the Galician coast, so that they increase their population by up to forty times. “In these circumstances, the bacteria break down the crude oil, converting it to carbon dioxide and water. When the oil has all been degraded, the bacteria population returns to its original numbers.” The bacteria are able to clean rock surfaces, oil spilt on earth, as well as fresh and salty water.

Because some of the polluting oil on the rocks is in thick deposits, up to three separate applications will be made at approximately one-month intervals, using industrial sprays to create a fine layer of S-200 that sticks to the pollutant. Contaminated waters can be cleaned by pouring in S-200, which adheres to the polluting oil until that is broken down. The application rate will be approximately 1 litre S-200 for every kilogram of oil pollution.

S-200 is a selective fertilizer, enriched with nitrogen, phosphorus and iron, that allows all-consuming hydrocarbon bacteria to attack the fuel. S-200 consists of a balanced nucleus of nutrients encapsulated by a oily membrane that adheres to hydrocarbon, and remains stuck to it until the bacteria are able “to eat” it all. The oily nature of the encapsulation also inhibits degradation of the S-200 by the weather. The bacteria already exist in the contaminated zone and when they have finished the work, they will “die of starvation”.

The technology of the S-200, based on oleic encapsulation, has been developed in the United States. It is approved by the United States Environmental Protection Agency and is a nontoxic product , “non-irritating, non-inflammable and totally ecological”, said Santiago Ramas.

Autonomous National Parks Organisation director, Basilio Rada, has personally verified that “the system works prefectly” and says that the Pontevedra “will be totally clean” by end of next April or the beginning of May, 2004. Rada describes this bio-cleaning system as superb, being able to clean zones in the rocky coastline inaccessible to mechanical cleaning systems.

There is an sister product, S-200 Bilge-Pro, which is designed to deal with the bilges of sports and industrial boats.


  • 1 litre S-200 to 1 kilogram oil pollution means that an awful lot of this product, a nitrogen-containing fertiliser, will be used.
  • Run-off from nitrogen-based fertilisers creates much pollution in both fresh and salt-water environments.

The claims for the benignity of S-200 appear excessive when these statements are taken into account.

related material
the politics of irresponsibility—the Prestige disaster

the web address for this article is


related material
the politics of irresponsibility
—the Prestige disaster


come into my parlour—inviting termites to try it on

“In the world’s largest experiment of its kind, scientists have set up 80 model homes on termite-infested land in the Northern Territory to test a range of novel anti-termite solutions.

“In a bid to curb the $780 million that termites cost Australians each year, The University of Melbourne, the Sunshine University, Queensland and the local Yolngu people have placed houses of either slab or raised floor construction with a variety of the latest defence systems against termites in Yolngu territory, Arnhem Land. The area harbours virtually every economically important species of termite known in Australia.”

the web address for this article is


flood modelling in real time, combining simulation with satellite imaging

“The US Geological Survey estimates that flooding is the world's most costly type of natural disaster, costing €170 billion ($200 billion) between 1991 and 1995. Last year's European floods alone are reported to have caused more than €7 billion of damage.

“Like everything linked to the weather, floods are difficult to predict - a few days of steady rainfall might be sufficient for a river to burst its banks.

“ What software-based flood simulation models can do is foretell how a river will behave if it does flood, and allow authorities to assess their best course of action.”

” The idea behind the FAME project was to use satellite data as an additional means of mapping flood extent in zones close to rivers as well as creating more accurate flood risk maps and carrying out post-flood damage assessment.”

With satellite and simulation illustrations.

the web address for this article is


group claims feedback system tends to produce fractal coastlines

“But there has never been an explanation for why coastlines are fractal, says Bernard Sapoval of the Ecole Polytechnique in Palaiseau, France.

“Until now, that is. "Fractal coastlines are best at damping waves," Sapoval explains. "As the coast damps down the waves, the erosion to which it is subjected is reduced.”

the web address for this article is


an approach to crippling computer virus attacks

“In nature, diseases are most devastating when an infection-causing organism encounters a "monoculture," a vast swath of genetically similar individuals, each susceptible to the organism's method of attack. In the same vein, computer viruses and worms exploit the same flaw on every computer running the same software.”

“ Our project seeks to reduce computer vulnerability by automatically changing certain aspects of a computer's software," said Dawn Song, an assistant professor of electrical and computer engineering and computer science at Carnegie Mellon. "Adapting this idea in biology to computers may not make an individual computer more resilient to attack, but it aims to make the whole population of computers more resilient in aggregate.”

the web address for this article is


droplet formation discovery—potential for making nano threads

“.....physicists at the University of Chicago has made a discovery about the formation of drops that could lead to new methods for making threads, wires and particles only a few nanometers wide.”

the web address for this article is


development of flywheels for power storage

“A flywheel made with the new technology set a speed record, spinning at 3,000 miles per hour, demonstrating the capability of storing 70 percent more energy than the same-sized flywheel made with current technology.”

“ High-speed flywheels offer several advantages over low-speed flywheels......High-speed flywheels store and release energy in a package that’s smaller and weighs less than other technologies...

“High-speed flywheels also last longer. Last year, researchers at The University of Texas at Austin charged and discharged a flywheel 110,000 times with no change in performance. In addition, a flywheel system can be operated so that it wastes less than 5-10 percent of the energy stored as it is charged and discharged. By comparison, chemical batteries can typically be charged and discharged a few tens of thousands of times at best and typically waste more than 20 percent of the energy on charging and discharging.

“NASA’s flywheel achievements, while directed toward space applications, are also expected to benefit companies using flywheels to improve power delivery for factories, businesses and hybrid vehicles.”

the web address for this article is


new states of matter research

“This is the first Bose-Einstein condensate made from molecules, rather than atoms. Gives a powerful new tool for investigating phenomena such as superconductivity.

“The molecular lithium condensate is also a step towards another physics grail: a hitherto unseen state of matter called the fermionic condensate.

“The first BEC was made in 1995 with rubidium atoms.”

In 1995, at Boulder Colorado, an entirely new state of matter was created as predicted decades previously by Albert Einstein and Indian physicist Satyendra Nath Bose.

Cooling rubidium atoms to less than 170 billionths of a degree above absolute zero caused the individual atoms to condense into a "superatom" behaving as a single entity...”

At this series of web-pages from Colorado University is a duffer’s guide to BECs, which may be created at very low temperatures. Various animated images explain and demonstrate concepts concerning BECs, including ‘making’ a BEC. Four GoldenYak (tm) Award

A start for the curious who wish to dig deeper, from enc brit.

subatomic particle with integral spin (i.e., angular momentum in quantum-mechanical units of 0, 1, etc.) that is governed by the Bose-Einstein statistics (q.v.). Bosons include mesons (e.g., pions and kaons), nuclei of even mass number (e.g., helium-4), and the particles required to embody the fields of quantum field theory (e.g., photons and gluons). Bosons differ significantly from a group of subatomic particles known as fermions in that there is no limit to the number that can occupy the same quantum state. This behaviour gives rise, for example, to the remarkable properties of helium-4 when it is cooled to become a superfluid.
any member of a group of subatomic particles having odd half-integral angular momentum (spin 1/2, 3/2), named for the Fermi-Dirac statistics that describe its behaviour. Fermions include particles in the class of leptons (e.g., electrons, muons), baryons (e.g., neutrons, protons, lambda particles), and nuclei of odd mass number (e.g., tritium, helium-3, uranium-233).

Fermions obey the Pauli exclusion principle, which forbids more than one particle of this type from occupying a single quantum state. This condition underlies, for example, the buildup of electrons within an atom in successive orbitals around the nucleus and thereby prevents matter from collapsing to an extremely dense state. Fermions are produced and undergo annihilation in particle-antiparticle pairs.
in particle physics, a [theory] symmetry between fermions (subatomic particles with half-integer values of intrinsic angular momentum, or spin) and bosons (particles with integer values of spin).

An entity is said to exhibit symmetry when it appears unchanged after undergoing a transformation operation. A square, for example, has a fourfold symmetry by which it appears the same when rotated about its centre through 90, 180, 270, and 360 degrees; four 90-degree rotations bring the square back to its original position.

the web address for this article is


real-world evolutionary biology text, 750,000 years old

“For at least a million years, owls throughout the West have been snapping up sagebrush voles and reducing them to gray pellets of fur, bones and teeth littering the foot of the roost.

“Thanks to pack rats, however, these voles have not been forgotten.

“In one Colorado cave, a pack rat collection of teeth and bones has yielded a layered slice of vole history between 600,000 and a million years ago, providing an unprecedented picture of how a species changes and evolves, and how its evolution is affected by climate change.

“Everything in the cave has been nicely preserved at a controlled temperature and humidity, like putting the stuff in a refrigerator for 750,000 years," said Tony Barnosky, a University of California, Berkeley, paleobiologist.”

“ It's likely that speciation takes place over a longer time interval than extinction," Barnosky said. "So, climate changes like the global warming we are seeing today are probably happening too fast to cause anything but extinction.”

the web address for this article is


manufacturing very nasty and dangerous bugs Two GoldenYak (tm) Award

“Since the anthrax attacks of 2001, the government has looked for ways to curb the dissemination of new and dangerous knowledge about disease-causing organisms. At the same time, experts have argued, the best way to prepare for a possible bioterrorism attack is to allow research to proceed as unimpeded as possible.”

This article is short clear and to the point.
(Ii have held back this news item until a suitable version appeared.)

the web address for this article is


lemmings—an answer

"....They found that the population of lemmings and their cousins, the
vole, can explode by 100 or even 1,000 times their original size.

That, in turn, boosts the predator numbers, which become so numerous and
gorge so much on the lemmings that the rodent numbers plummet
dramatically. The next phase is that the lack of lemming drives down the
predator numbers.

Predator-prey cycles such as this are familiar to biologists, but what is
interesting in this case is that, with the lemmings, the pattern is almost
like clockwork. It is a four-year "boom and bust" cycle whose key is the
stoat, a specialist predator whose only source of food is the lemming...."

related material
feedback and crowding

the web address for this article is


related material
feedback and


fully functioning computer the size of a pack of cards

“Geyer argues that even now the MCC is good value for money, as it can replace a desktop, laptop and PDA and requires only one software platform to be paid for and supported. He also highlights the time that could be saved by not having to transfer data between three devices.”

the web address for this article is


the smoothing effect of large numbers Three GoldenYak (tm) award

“The basic idea is simple: we replace the atoms of conventional statistical mechanics by people. Of course, while atoms interact via well defined forces of attraction and repulsion, people are seldom so straightforward. But in some situations human interactions do not amount to very much more than this basic concept. For example, by avoiding collisions and not encroaching on one another's "personal space", we act just as though there was a repulsive force between us.”

It is vital when reading this item to keep in mind the radical differences between statistical models and individual behaviour. See ‘intelligence’: misuse and abuse of statistics for more detail.

related material
section on modelling

the web address for this article is


related material
section on


new frog from a very old family

“A bright purple frog shaped like a donut with a pointy snout has been discovered in the mountains of southern India.

“The seven-centimeter long amphibian hopped around the feet of dinosaurs. Researchers say the small-headed critter belongs to a new family of frogs thought to have disappeared millions of years ago.”

With a small picture.

related material
human classification systems, using the example of classification of ‘living organisms’ (taxonomy)

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related material
human classification systems, using the example of classification of ‘living organisms’ (taxonomy)


gene expression in chimps and humans

“Using gene chips to compare samples of the cerebral cortex of humans, chimpanzees and rhesus monkeys, the research team at the Salk, the Yerkes Center and UCLA identified 91 genes that are expressed in different amounts in humans compared to the other primate species. Upon further study, the team observed 83 of these genes showed higher levels of activity in humans, and as a result, regulated neural activity.”

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