Esses are everywhere.

From economic trends, population growth, the spread of cancer, or the adoption of new technology, certain patterns inevitably seem to emerge. A new technology, for example, begins with slow acceptance, followed by explosive growth, only to level off before “hitting the wall.”

When plotted on graph, this pattern of growth takes the shape of an “S.”

While this S-curve has long been recognized by economists and scientists, a Duke University professor believes that a theory he developed explains the reason for the prevalence of this particular pattern, and thus provides a scientific basis for its appearance throughout nature and the man-made world.

“This phenomenon is so common that it has generated entire fields of research that seem unrelated – the spread of biological populations, chemical reactions, contaminants, languages, information and economic activity,” said Adrian Bejan, engineering professor at Duke’s Pratt School of Engineering. “We have shown that this pattern can be predicted entirely as a natural flow design.”

The concept of flow design, whether it be energy, rivers or human populations, is central to Bejan’s theory.

The results of this theory of the S-curve, conducted with collaborator Sylvie Lorente from the University Toulouse, France, were published online in the Journal of Applied Physics. The research was supported by the National Science Foundation, the U.S. Air Force Office of Scientific Research and the National Renewable Energy Laboratory.

Bejan’s theory, known as the constructal law, is based on the principle that flow systems evolve their designs over time to facilitate flow access, reducing and distributing friction or other forms of resistance. Bejan developed the principle 15 years ago, and has been using it to describe and predict a wide variety of man-made and natural phenomena.

The current analysis views this ubiquitous S-curve (also known as the sigmoid function) as a natural design of flow systems. In the example of a new technology, after a slow initial acceptance, the rise can be imagined moving fast through established, though narrow, channels into the market place. This is the steep upslope of the "S."

As this technology matures, and its penetration slows, any growth, or flow, moves outward from the initial penetration channels in a shorter and slower manner. Bejan likes to the use metaphor of fingers stretching out to represent the initial invasive growth, with the placement of a glove over those fingers as a representation of the lateral consolidation phase.

“It’s like there are two lives – the first is long and fast, while the second phase is short and slow,” Bejan said. “The trend begins with a quick ‘invasion,’ followed by a ‘slower’ consolidation. Then the trend hits a wall.”

This pattern matches that of the constructal theory, which uses a large river basin as a visual description of flow systems, growing fast and far, with smaller branches growing laterally from the main channels.

The prevalence of the S-curve phenomena in nature rivals that of the tree-shaped flows, which also unite the animate, inanimate and human realms,” Bejan said. “This theory shows that this is not a coincidence – both are manifestations of the natural constructal tendency of flow systems to generate evolving designs that allow them to flow, spread and collect more easily.”

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Scientists of the CDF collaboration at the Department of Energy’s Fermi National Accelerator Laboratory announced the observation of a new particle, the neutral Xi-sub-b (Ξ_b⁰). This particle contains three quarks: a strange quark, an up quark and a bottom quark (s-u-b). While its existence was predicted by the Standard Model, the observation of the neutral Xi-sub-b is significant because it strengthens our understanding of how quarks form matter. Fermilab physicist Pat Lukens, a member of the CDF collaboration, presented the discovery at Fermilab on Wednesday, July 20.

The neutral Xi-sub-b is the latest entry in the periodic table of baryons. Baryons are particles formed of three quarks, the most common examples being the proton (two up quarks and a down quark) and the neutron (two down quarks and an up quark). The neutral Xi-sub-b belongs to the family of bottom baryons, which are about six times heavier than the proton and neutron because they all contain a heavy bottom quark. The particles are produced only in high-energy collisions, and are rare and very difficult to observe.

Although Fermilab’s Tevatron particle collider is not a dedicated bottom quark factory, sophisticated particle detectors and trillions of proton-antiproton collisions have made it a haven for discovering and studying almost all of the known bottom baryons. Experiments at the Tevatron discovered the Sigma-sub-b baryons (Σ_b and Σ_b*) in 2006, observed the Xi-b-minus baryon (Ξ_b^-) in 2007, and found the Omega-sub-b (Ω_b^-) in 2009. The lightest bottom baryon, the Lambda-sub-b (Λ_b), was discovered at CERN. Measuring the properties of all these particles allows scientists to test and improve models of how quarks interact at close distances via the strong nuclear force, as explained by the theory of quantum chromodynamics (QCD). Scientists at Fermilab and other DOE national laboratories use powerful computers to simulate quark interactions and understand the properties of particles comprised of quarks.

Once produced, the neutral Xi-sub-b travels a fraction of a millimeter before it decays into lighter particles. These particles then decay again into even lighter particles. Physicists rely on the details of this series of decays to identify the initial particle. The complex decay pattern of the neutral Xi-sub-b has made the observation of this particle significantly more challenging than that of its charged sibling (Ξ_b^-). Combing through almost 500 trillion proton-antiproton collisions produced by Fermilab’s Tevatron particle collider, the CDF collaboration isolated 25 examples in which the particles emerging from a collision revealed the distinctive signature of the neutral Xi-sub-b. The analysis established the discovery at a level of 7 sigma. Scientists consider 5 sigma the threshold for discoveries.

CDF also re-observed the already known charged version of the neutral Xi-sub-b in a never before observed decay, which served as an independent cross-check of the analysis. The newly analyzed data samples offer possibilities for further discoveries.

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By Larry O’Hanlon, ISNS Contributor

(ISNS)—Scientists have discovered that male black widow spiders, famous for ending up as their mates’ post-coital supper, are not as clueless as you might think. In a series of careful experiments, a team of researchers from Arizona State University West in Glendale has teased out evidence that black widow males do their best to avoid getting eaten by choosing mates who have recently fed.

The work also details something else very rare in the animal kingdom: a sexual power struggle in which males have the upper hand.

"Most of the time people focus on females" when it comes to the power of selecting mates, said spider researcher Eileen Hebets at the University of Nebraska in Lincoln. That power is critical to adaptation and evolution, and ultimately shapes the species. "It’s much less common to think of males as a potential source of selection," she said.

It’s only in extreme situations—where mating brings the risk of death, for example—that male selection appears and can be studied.

In the case of the North American black widow, Latrodectus hesperus, the Arizona experiments reveal that male black widows can detect telltale chemical signals on the webs of females. They can smell which females are well-fed and which are hungry, which leads to a simple choice: Which one is less likely to eat them? This ability to sense well-fed females also has another advantage: by choosing plump females, males are also choosing mates that are likely to produce large numbers of eggs.

"It’s a double whammy," said Chad Johnson, the lead investigator on the study, which was published in the August issue of the journal Animal Behaviour .

In most animal species, females dictate the course of reproduction, said Johnson. They work hard to produce and safeguard a few eggs, while males generate lots of sperm at little personal cost. That difference in "investment" usually leads males to be promiscuous while females are choosy. But in species like the black widow, the danger of mating is so great for the males that they have to be the choosy ones.

To check this idea, the Arizona team put their laboratory-raised black widows through four experiments. First, they tested whether males were more likely to engage in courting behavior on the webs of well-fed females more than on the webs of hungry females—even in the absence of the females themselves. The lab spiders did exactly that.

In their second experiment, the researchers put the females back into the mix. Again, the males greatly preferred the plump females.

Next, the team pulled a confusing switcheroo on the males by putting well-fed females on the webs of starved females and starved females on the webs of well-fed females. For the most part, the males’ behavior reflected this confusion by showing no significant preference for the well-fed females that were placed on the wrong webs.

Finally, the researchers rolled up onto sticks webs from females that were either well-fed or starving and presented them to males to find out if it was a chemical or structural difference in the web that was cluing in the males. Once again, the males preferred the webs of well-fed females, supporting the idea that the clue is some unknown chemical in the webs that the males can smell.

"He’s not at all complicit in his own demise," said Johnson of the black widow males. "He’s making the best of a bad situation."

Despite their efforts, though, male black widows frequently don’t survive mating. Although the rates of survival were not the focus of this study, in some other widow species the risk of getting eaten is much greater.

"There is almost a continuum with spiders of varying degrees of risk," said Hebets. This is exactly what makes them so fascinating to study, she added.

There are even some species where males can get eaten before mating. "That’s obviously an even more extreme freak show," said Johnson.

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By Juli Berwald, ISNS Contributor

(ISNS)—You’re probably familiar with barcodes, those black and white stripes on most store items that bring about the familiar "beep" when scanned at checkout. They determine whether a scanned item is a gallon of milk or a can of tomato soup.

Eight years ago, biologists developed their own sort of barcode that’s also used for identification, but these barcodes aren’t printed on the outside of items. Instead, they are found inside the DNA of plants and animals studied by biologists.

Research presented this week during a meeting of the Ecological Society of America reveals that genetic barcodes have become a powerful tool in ecology, not just for identification, but also for understanding ecosystem interactions.

Genetic barcodes are a sequence of a particular segment of DNA that has just the right amount of variability to identify what species it came from. When an unknown creature—or part of a creature—is found, its tissue can be barcoded. If the sequence matches another barcode in one of several international databases, the creature’s identity is revealed.

Biologist Dan Janzen of the University of Pennsylvania has been studying insects and the plants they eat in the northwestern corner of Costa Rica since 1975. Janzen and collaborators collected nearly half a million caterpillars, reared about 5,000 different species of moths and butterflies to adulthood and inventoried 2,000 species of insect parasites—or so Janzen thought.

In 2003, Janzen’s group began barcoding their insect inventory. What they had assumed was a single butterfly species eating 10 different species of plants actually turned out to be 10 separate butterfly species each consuming a single plant; what looked like a single wasp species was really 36 distinct species; and what appeared to be 16 species of flies were in fact 73 unique species.

In one instance, Janzen had collected imperial moths living just one kilometer apart. The DNA barcodes from the two populations had an 8 percent difference, evidence of a single species splitting in two.

On the French Polynesian island of Moorea near Tahiti in the South Pacific, a massive barcoding effort has been in the works for four years. From the tops of its mountains to the depths of its ocean, an international team of scientists has been identifying and barcoding all organisms larger than about a millimeter.

To date, the scientists have inventoried more than two-thirds of the island’s inhabitants—about 6,500 species. Such comprehensive coverage is the first step for studying the ecosystem in places where there aren’t many recognizable features of a critter—say, the insides of a fish’s stomach.

Deciphering a fish’s diet from its stomach contents is like determining what clothes produced the lint in your clothes dryer, explains Chris Meyer of the Smithsonian Institution and director the Moorea Biocode Project. If you find a button, it’s easy to tell what pair of shorts it came from. But what if those bits of stringy fluff came from your blue towel or your blue jeans? That’s where barcoding offers a powerful solution.

Meyer and his colleagues, Matthieu Leray and J. T. Boehm, sequenced the fluffy stomach contents of three species of fishes, teasing out barcodes from the collective mush. An astonishing 69 prey species matched barcodes from their database—an assortment of creatures including worms, other fish, mollusks, and crustaceans. Surprisingly, only two prey species—a snapping shrimp and a squat lobster—were eaten by more than one type of predator. Meyer said that the predator’s choice of prey, at least for the species in this study, "are more highly partitioned than we expected."

Ecologists are starting to wire such detailed predator and prey linkages into ecosystem models to test how such resource partitioning might support the resilience of the reef, especially when faced with stressors such as climate change and recent increases of invasive species.

Barcoding projects are now underway throughout the globe. Near the Arctic Circle in Churchill, Canada, scientists have cataloged 6,000 species, including an unexpectedly large number of insects. In New Guinea, barcodes are used to understand the evolution of butterflies. And in Puerto Rico they’re used to decipher how forests are structured.

Ago 19, 2011
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El líder ecologista Juan López de Uralde, que aspira a presentarse a las elecciones generales del 20-N con el nuevo partido Equo, no tendrá que hacer campaña desde una cárcel danesa. Ayer, en la segunda vista del juicio que se celebra contra él y diez activistas de Greenpeace en Copenhague,el fiscal pidió 60 días de prisión suspendida para cada uno y una multa de 30.000 euros para la delegación danesa de la ONG. La petición de la Fiscalía, una pena simbólica, implica que los acusados no tendrán que pisar de nuevo la cárcel. La sentencia definitiva se conocerá el lunes.

Ago 20, 2011
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Gran parte del terror sobre la pasada pandemia de gripe residía en la posibilidad de que el nuevo virus H1N1 pudiera coincidir con el virus estacional en una misma célula. En su interior, ambos podrían intercambiar su material genético y generar una nueva variante que pudiera portar lo peor de cada casa: una alta capacidad de transmisión y una mayor mortalidad.

Algo así ha ocurrido en el microorganismo causante de la leishmaniasis, la segunda enfermedad parasitaria más importante después de la malaria. Transmitida por la picadura de un mosquito y afincada prácticamente en el Tercer Mundo, afecta a cerca de dos millones de personas en 88 países.

Analizando genéticamente distintas cepas de leishmania en el Instituto de Medicina Tropical de la Universidad de Amberes, se ha descubierto una cepa del parásito cuya composición genética sólo puede explicarse como resultado de una reproducción sexual entre especies.

La primera evidencia de que existiera este tipo de reproducción se publicó en Science en abril del 2009, por David L. Sacks, director del Laboratorio de Enfermedades Parasitarias de la Universidad de Washington. Su grupo descubrió que, en el laboratorio, distintas cepas de leishmania podían intercambiar ADN en el interior del mosquito.

Ago 19, 2011
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La oficina de patentes de EEUU concedió este martes la patente ocho millones. Este país, que tardó 75 años en registrar su primer millón y 25 años en lograr el segundo, ha hecho la última cifra en sólo cinco. La mayoría de esas patentes son tecnológicas (sólo IBM registra más del doble que la industria española), y entre los 20 mayores registradores sólo aparecen dos empresas no tecnológicas: Honda y General Electric. Pero ¿significa esto que la industria de la tecnología vive una brillante era de innovación? Los expertos tienen sus dudas.

Nokia llevó a los tribunales a Apple por la infracción de diez de sus patentes en 2009. La compañía de Steve Jobs, a su vez, demandó a la empresa finlandesa, que contraatacó añadiendo a sus quejas más registros. Samsung, que vio cómo un juez alemán bloqueaba la venta en Europa de su tableta Galaxy Tab 10.1 la semana pasada (orden ya levantada), también fue llevada a los tribunales por Apple. Pero esta compañía, por otro lado, ha sido demandada por el fabricante HTC. Por otro lado, Oracle quiere que Google le pague 6.000 millones porque, supuestamente, el sistema operativo Android (de Google) usa el software Java (de Oracle). Y Microsoft tiene pendientes casos contra Motorola y cobra hasta cinco euros por cada HTC que se vende. Ese es el alocado panorama de la industria tecnológica actual.

“En el sector del móvil hay una carrera armamentística en toda regla. Las patentes son almacenadas como un arsenal con el fin de obligar a los rivales a acuerdos de intercambio de licencias”, dice el experto en propiedad intelectual Florian Mueller. Para este veterano activista de la lucha contra las patentes de software, reconvertido en consultor, estamos ante una reedición del concepto de destrucción mutua de la Guerra Fría, en la que ninguno de los bandos atacaba al otro porque conllevaría su propia destrucción.

Pero esta guerra es más complicada. No es un conflicto bipolar. Entre los grandes contendientes están Microsoft, y su reciente aliado Nokia, Oracle, que va por su cuenta, o Apple, con diferencia la más combativa. Google y la constelación de fabricantes que usan Android en sus aparatos centran buena parte del conflicto. Las líneas maestras de la contienda son muy sencillas: las escaramuzas empiezan en los tribunales. Apple, por ejemplo, demandó a HTC por violar dos de sus patentes. La firma taiwanesa respondió comprando en julio una empresa llamada S3 Graphics que, casualmente, había conseguido que un juez condenara a Apple por vulnerar su propiedad intelectual. Con ese movimiento, HTC se armó para el fin habitual en estos casos: un intercambio de patentes o un acuerdo de licencias compartido.

Pero hay quienes no juegan con esa lógica. En EEUU han surgido bufetes expertos en litigar por la propiedad intelectual e industrial y, peor aún, lo que se conocen como los trolls

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