Fermilab Physicists Discover "triple-scoop" Baryon

Physicists of the DZero experiment at the Department of Energy's Fermi National Accelerator Laboratory have discovered a new heavy particle, the Ξb (pronounced "zigh sub b") baryon, with a mass of 5.774±0.019 GeV/c2, approximately six times the proton mass. The newly discovered electrically charged Ξb baryon, also known as the "cascade b," is made of a down, a strange and a bottom quark. It is the first observed baryon formed of quarks from all three families of matter. Its discovery and the measurement of its mass provide new understanding of how the strong nuclear force acts upon the quarks, the basic building blocks of matter.

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The cascade b is produced in high-energy proton-antiproton collisions at Fermilab's Tevatron. A baryon is a particle of matter made of three fundamental building blocks called quarks. The most familiar baryons are the proton and neutron of the atomic nucleus, consisting of up and down quarks. Although protons and neutrons make up the majority of known matter today, baryons composed of heavier quarks, including the cascade b, were abundant soon after the Big Bang at the beginning of the universe.

Six quarks -- up, down, strange, charm, bottom and top -- are the building blocks of matter. Protons and neutrons are made of up and down quarks, held together by the strong nuclear force. The DZero experiment, in which six Louisiana Tech researchers participated, has discovered the cascade-b particle, which contains a down quark (d), strange quark (s) and bottom quark (b). It is the first particle ever observed with one quark from each generation of particles. (Graphic and information supplied by Fermilab.)

The Standard Model elegantly summarizes the basic building blocks of matter, which come in three distinct families of quarks and their sister particles, the leptons. The first family contains the up and down quarks. Heavier charm and strange quarks form the second family, while the top and bottom, the heaviest quarks, make the third. The strong force binds the quarks together into larger particles, including the cascade b baryon. The cascade b fills a missing slot in the Standard Model.

Once produced, the cascade b travels several millimeters at nearly the speed of light before the action of the weak nuclear force causes it to disintegrate into two well-known particles called J/Ψ ("jay-sigh") and Ξ- ("zigh minus"). The J/Ψ then promptly decays into a pair of muons, common particles that are cousins of electrons.

Direct observation of the strange b baryon Xi_b^{-}. 2007. Authors: D0 Collaboration, V. Abazov, et al., Physical Review Letters, preprint.

Designer Lizards

Researchers have found that female side-blotched lizards are able to induce different color patterns in their offspring in response to social cues, "dressing" their progeny in patterns they will wear for the rest of their lives. The mother's influence gives her progeny the patterns most likely to ensure success under the conditions they will encounter as adults.

Spider-Man & The Lizard © Marvel Comics

The lizards' main predator, the coachwhip snake, is a highly efficient hunter, and the lizards need just the right combination of traits to avoid being eaten. Sneaky yellow-throated males like to hide in the grass and need a barred pattern that breaks up the outline of their body so it blends in with the background. Aggressive orange males spend a lot of time in the open and need stripes to help them escape from predators (the optical effect of stripes on fast-moving prey makes them hard to catch).

The researchers reported that female side-blotched lizards give an extra dose of the hormone estradiol to their eggs in certain social circumstances. The extra hormone affects the back patterns of lizards that hatch from those eggs, creating either lengthwise stripes down their backs or bars stretching from side to side. Whether they get stripes or bars depends on the genes for other traits.

"This is the first example in which exposure to the mother's hormones changes such a fundamental aspect of appearance. Even more exciting is that the mother has different patterns at her disposal, so she can ensure a good match between back patterns and other traits that her offspring possess," said Lesley Lancaster. link

The Chance Chemistry of Life

A pair of UCSF scientists has developed a model explaining how simple chemical and physical processes may have laid the foundation for life.

The basic idea is that simple principles of chemical interactions allow for a kind of natural selection on a micro scale: enzymes can cooperate and compete with each other in simple ways, leading to arrangements that can become stable, or “locked in,” says Ken Dill.

The scientists compare this chemical process of “search, selection, and memory” to another well-studied process: different rates of neuron firing in the brain lead to new connections between neurons and ultimately to the mature wiring pattern of the brain. Similarly, social ants first search randomly, then discover food, and finally build a short-term memory for the entire colony using chemical trails.

They also compare the chemical steps to Darwin’s principles of evolution: random selection of traits in different organisms, selection of the most adaptive traits, and then the inheritance of the traits best suited to the environment (and presumably the disappearance of those with less adaptive traits).

Like these more obvious processes, the chemical interactions in the model involve competition, cooperation, innovation and a preference for consistency, they say.

In its simplest form, the model shows how two catalysts in a solution, A and B, each acting to catalyze a different reaction, could end up forming what the scientists call a complex, AB. The word “complex” is key because it shows how simple chemical interactions, with few players, and following basic chemical laws, can lead to a novel combination of molecules of greater complexity. The emergence of complexity – whether in neuronal systems, social systems, or the evolution of life, or of the entire universe -- has long been a major puzzle, particularly in efforts to determine how life emerged.

“A major question about life’s origins is how chemicals, which have no self-interest, became ‘biological’ -- driven to evolve by natural selection,” he says. “This simple model shows a plausible route to this type of complexity.” link

Stochastic innovation as a mechanism by which catalysts might self-assemble into chemical reaction networks. 2007. Justin A. Bradford and Ken A. Dill. PNAS

Cannibalistic Fish Keep Their Shape

Some fish of the same species display very different features (“resource polymorphism”) even though they live in the same lake because they eat different foods. A team of European researchers found that early cannibalism is found in all species displaying resource polymorphism.

The effect of early cannibalism is twofold. First, it stabilizes the variation in the number of individuals over time, which in turn increases the benefit of specializing on any resource since the risk of being dependent on a vanishing resource decreases. Second, an early disappearance of small newborn individuals increases the abundance of their prey due to decreased consumption from the small ones, hence increasing the benefit for larger individuals to specialize on this specific prey (typically zooplankton). link

Stabilization of population fluctuations due to cannibalism promotes resource polymorphism in fish. 2007. Jens Andersson, et al. American Naturalist 169:820–829.

Super Fungi Feed on Radiation

Art © Steve Ditko. Space Adventures © current copyright holder.

Scientists have long assumed that fungi exist mainly to decompose matter into chemicals that other organisms can then use. But researchers have found evidence that fungi possess a previously undiscovered talent with profound implications: the ability to use radioactivity as an energy source for making food and spurring their growth.

Those fungi able to "eat" radiation must possess melanin, the pigment found in many if not most fungal species. But up until now, melanin's biological role in fungi—if any--has been a mystery.

"Just as the pigment chlorophyll converts sunlight into chemical energy that allows green plants to live and grow, our research suggests that melanin can use a different portion of the electromagnetic spectrum—ionizing radiation—to benefit the fungi containing it," says Dr. Dadachova.

The research began five years ago when Dr. Casadevall read on the Web that a robot sent into the still-highly-radioactive damaged reactor at Chernobyl had returned with samples of black, melanin-rich fungi that were growing on the reactor's walls.

Fungi exposed to levels of ionizing radiation approximately 500 times higher than background levels grew significantly faster (as measured by the number of colony forming units and dry weight) than when exposed to standard background radiation. link

Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi. Ekaterina Dadachova, et al. PLoS ONE 2(5): e457.

Pat Boyette: Carrion of the Gods

An on-line article HERE wondered if Pat Boyette and Steve Ditko were the same person. A quick search of the web would show that Boyette produced a lot of great work, most of which was for the ‘smaller’ publishers (e.g. Charlton) and included a lot of nifty gothic horror and Sci-Fi material like this fondly remembered tale:

CLICK TO ENLARGE AND READ














From Tales of the Macabre #2. Story & Art © Estate of Pat Boyette.

Read a nice interview with Boyette.

A short bio of the man is HERE

Bigger Is Better (& Smarter)

When it comes to estimating the intelligence of various animal species, it may be as simple measuring overall brain size. In fact, making corrections for a species' body size may be a mistake.

"It's long been known that species with larger body sizes generally have larger brains," said Robert Deaner. "Scientists have generally assumed that this pattern occurs because larger animals require larger nervous systems to coordinate their larger bodies. But our results suggest a simpler reason: larger species are typically smarter."

Deaner said the findings imply that a re-evaluation may be in order for many previous studies that have compared brain size across different animal species, including ancestral hominids.

The new results showed that some primate species consistently outperform others across a broad range of cognitive tasks. It compared how well eight different brain size measures predicted the domain-general cognition variable generated in the earlier study. To the researchers' surprise, overall brain size and overall neocortex size proved to be good predictors, but the various measures that controlled for body size did not. The results did not change even when various statistical assumptions were altered.

Another unexpected finding was that the overall size of the whole brain proved to be just as good a predictor of intelligence as was the overall size of the neocortex. Scientists making cross-species comparisons have often assumed that the neocortex would be more closely linked to intelligence, since it is considered the "thinking part" of the brain. link

Overall Brain Size, and Not Encephalization Quotient, Best Predicts Cognitive Ability across Non-Human Primates. 2007. R. O. Deaner, et al. Brain, Behavior, and Evolution 70: 115-124.