A Blog Around The Clock

My picks for today:
Segregation of Odor Identity and Intensity during Odor Discrimination in Drosophila Mushroom Body:

Considerable progress has been made in understanding how olfaction works as the receptor proteins, sensory neurons, and brain circuitry responsible have become increasingly well-characterized. However, olfactory processing in higher brain centers, where neuronal activity is assembled into the perception of odor quality, is poorly understood. Here, we have addressed how the mushroom body (MB)–a secondary olfactory center–is involved in olfactory discrimination. We manipulated the MB by ablation, disruption of synaptic transmission, and interruption of key cellular signaling molecules in naïve flies and in flies trained to discriminate odors. We first show that although both odor identity and intensity are encoded in the MB, only the former requires Gαq-dependent signaling and is necessary for naïve flies to spontaneously discriminate different odors. We then show that training flies to alter their olfactory response requires Gαs-mediated signaling in MB for both odor intensity and odor identity. We have thus identified (i) segregation of odor identity and odor intensity at the MB level in naïve flies and (ii) different G-protein-dependent signaling pathways for spontaneous versus experience-dependent olfactory discrimination.

Viral Evolution in the Genomic Age:

Genome sequence data will undoubtedly deliver much to the study of viral pathogens and their diseases. A prominent example of this new genomic perspective is influenza A virus, for which a large-scale genome sequencing project begun in the year 2005 has, to date, generated around 2,500 complete viral genomes [1]. While this alone is newsworthy, the rise of rapid, high-throughput genome “pyrosequencing” promises to take the production of viral genomes to a level once unimaginable [2].

Saber-toothed Cat Was More Like A Pussycat Than A Tiger:

In public imagination, the sabre-toothed cat Smilodon ranks alongside Tyrannosaurus rex as the ultimate killing machine. Powerfully built, with upper canines like knives, Smilodon was a fearsome predator of Ice-Age America’s lost giants. For more than 150 years, scientists have debated how this iconic predator used its ferocious fangs to kill its prey. Now a new Australian study, published recently in the US Proceedings of the National Academy of Science, hopes to lay the arguments to rest. And the results will put in dent in Smilodon’s reputation.

Thriving Hybrid Salamanders Contradict Common Wisdom:

A new UC Davis study not only has important findings for the future of California tiger salamanders, but also contradicts prevailing scientific thought about what happens when animal species interbreed.

Three-way Mating Game Of North American Lizard Found In Distant European Relative:

An intricate three-way mating struggle first observed in a species of North American lizard has been discovered in a distant relative, the European common lizard. The two species are separated by 5,000 miles and 175 million years of evolution, yet they share behavioral and reproductive details right down to the gaudy colors of the males, according to new research published in the November issue of American Naturalist.

Saving Microscopic Threatened Species:

The Smithsonian’s National Zoo recently acquired 12,000 new animals–microscopic Elkhorn coral larvae harvested by National Zoo scientists in Puerto Rico–as part of an international collaborative program to raise the threatened species. National Zoo scientists hope to one day return the animals, once they are grown, to their wild ocean habitat.

Saltwater Crocodiles Can Find Their Way Home:

Three crocodiles relocated from their homes in Far North Queensland have been tracked swimming between 10 and 30 kilometres per day according to a collaborative research project by The University of Queensland, Australia Zoo and Queensland Parks and Wildlife Service.
————-
The results highlighted the success of satellite tracking for crocodiles allowing continuous tracking without human interference.
Professor Franklin said “Satellite technology is a great way of tracking these really cryptic animals which are difficult to follow.
“The success of the study was also recognition of the skills and knowledge that Steve Irwin brought to the project.”
He said Steve Irwin was a major driving force behind the study, and his intellectual and logistical support complimented the knowledge, experience and contributions made by the other team members.
“He also gave us the assistance of the croc team from Australia Zoo, who are highly skilled in the capture and care of crocodiles.”
All three monitored crocodiles were moved by helicopter between 52 and 130 kilometres away but still found their way back to their capture sites. One crocodile was flown across Cape York Peninsula from the west to east coast, and then circumnavigated the peninsula to return home.
He said crocodiles probably used many factors such as its position to the sun, magnetic fields, sight, and smell to navigate.

Sea Otter, Peregrine Falcon Back From The Brink Of Extinction But Other Species At Risk In Canada:

There’s good news and bad news in the report the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) just dropped on the Minister of the Environment’s desk.

Chesapeake Bay’s Habitats Threatened By Global Warming:

A new report on the impact of global warming on the Chesapeake Bay calls for a major shift in how land is managed in the bay to protect the nation’s most prized hunting and fishing grounds.

Surprise In The Organic Orchard — A Healthier Worm In The Apple:

Insects can catch more than a cold from certain viruses. Some viruses can be lethal to pest species – turning their insides to soup – without harming beneficial insects or other organisms. Hence they are used as an environmentally friendly means of biological crop protection worldwide. The proverbial worm in the apple, the codling moth caterpillar, has been controlled in European orchards for years with a baculovirus called codling moth granulovirus (CpGV). But in southwest Germany, some organic apple growers noticed that the virus was losing its effectiveness. Pest resistance to chemical insecticides is common in agriculture, but resistance to viruses had never been a problem in the past.

Going Fishing? Catch-and-release In Less Than Four Minutes, Please:

Recreational fishing that involves catch-and-release may seem like just good fun, and that released fish go on to live happily ever after, but a recent study at the University of Illinois shows that improper handling techniques by anglers can increase the likelihood of released fish being caught by predators.

Does The Victim Affect Snake Venom Composition?:

A snake’s intended prey might affect the type and evolution of toxins in their venom, research published in BMC Evolutionary Biology shows. In snakes, venom composition varies both between species and within a particular species. Land snakes feed on a range of animals and birds, so scientists think that these snakes need a diverse array of toxins in their venom. Sea snakes, on the other hand, tend to have a more restricted diet, feeding only on fish. The toxins in these snakes have now been shown to be less diverse than those in terrestrial snakes.

Tiny Animals Exposed To Outer Space:

“For the first time ever, animals are now being exposed to an unmitigated space environment, with both vacuum conditions and cosmic radiation,” says the ecologist Ingemar Jönsson, a researcher at Kristianstad University in Sweden. One of the aims of sending the tiny tardigrades into space is to find out whether they can cope with the rugged conditions in space, which has previously been predicted but never tested.

Antarctic Plants And Animal Life Survived Ice Ages:

Springtails, mites, worms and plant life could help solve the mystery of Antarctica’s glacial history according to new research published in the journal Science.

Fish Diet Linked To Evolution, Ten Million Year Old Chipped Teeth Show:

Chips from 10 million years ago have revealed new insights into fish diets and their influence on fish evolution, according to new research featured in this week’s issue of the journal Science. The chips were found, along with scratches, on the teeth of fossil stickleback fish and reveal for the first time how changes in the way an animal feeds control its evolution over thousands of years.

Does Your Mood Take A Nosedive Each November?:

If you notice that your mood, energy level and motivation take a nosedive each November only to return to normal in April, you may have Seasonal Affective Disorder (SAD), according to Loyola University Health System doctors.

Hormone-driven Effects On Eating, Stress Mediated By Same Brain Region:

A hormone system linked to reducing food consumption appears to do so by increasing stress-related behaviors, according to a new study. Mediated by a hormone receptor protein known as the corticotropin-releasing factor type 2 (CRF2) receptor, the system has attracted recent interest for its role in regulating food intake, say Vaishali Bakshi and Ned Kalin, professors in the Department of Psychiatry at the University of Wisconsin-Madison School of Medicine and Public Health.

Program Provides Blueprint For Recruiting Minorities To Science And Engineering:

The Model Institutions for Excellence Program (MIE) funded by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA) has developed a body of work over the past 11 years demonstrating successful strategies for recruiting underrepresented minority students to science and engineering fields and supporting their successful completion of science degrees.

Babies Raised In Bilingual Homes Learn New Words Differently Than Infants Learning One Language:

Research on the learning process for acquiring two languages from birth found differences in how bilingual babies learned words compared to monolingual babies. The research suggests that bilingual babies follow a slightly different pattern when using detailed sound information to learn differences between words.

Altruism Evolved From Maternal Behavior, Wasp Genetics Study Suggests:

Researchers at the University of Illinois have used an innovative approach to reveal the molecular basis of altruistic behavior in wasps. The research team focused on the expression of behavior-related genes in Polistes metricus paper wasps, a species for which little genetic data was available when the study was begun. Like honey bee workers, wasp workers give up their reproductive capabilities and focus entirely on nurturing their larval siblings, a practice that seems to defy the Darwinian prediction that a successful organism strives, above all else, to reproduce itself. Such behaviors are indicative of a eusocial society, in which some individuals lose, or sacrifice, their reproductive functions and instead work to benefit the larger group.

City Birds Better Than Rural Species In Coping With Human Disruption:

Birds that hang out in large urban areas seem to have a marked advantage over their rural cousins — they are adaptable enough to survive in a much larger range of conditions.

Crabs Prefer A Take-out Meal:

Shore crabs (Carcinus maenas) catch their food at food-rich spots and subsequently eat it elsewhere. With this take-out strategy the crabs maximise their food uptake and keep competing crabs at a distance, says Dutch researcher Isabel Smallegange.

Is There Any Validity To The So-called 5-second Rule?:

If a piece of toast fell on the floor, would you pick it up and eat it? You probably would if you believe in the 5-second rule, which suggests that your spilled breakfast stays germ-free as long as you snatch it up in five seconds.

Cockroaches Are Morons In The Morning, Geniuses In The Evening:

In its ability to learn, the cockroach is a moron in the morning and a genius in the evening. Dramatic daily variations in the cockroach’s learning ability were discovered by a new study performed by Vanderbilt University biologists and published online recently in the Proceedings of the National Academy of Sciences.

DNA Extracted From Woolly Mammoth Hair:

Stephan C. Schuster and Webb Miller of Penn State, working with Thomas Gilbert from Copenhagen and a large international consortium, discovered that hair shafts provide an ideal source of ancient DNA — a better source than bones and muscle for studying the genome sequences of extinct animals. Their research achievement, described in a paper to be published in the journal Science on Sept. 28, includes the sequencing of entire mitochondrial genomes from 10 individual woolly mammoths.

What Protects Us From Sunburn Also Protects Crayfish Against Bacteria:

The production of melanin in our skin helps protect us from the sun’s rays, but it also helps protect invertebrate animals — in their case, by encapsulating attacking fungi and parasites.

Second Extremely Resistant Bacteria Sequenced Is Surprisingly Different From First:

Researchers have completed the whole-genome sequence of Deinococcus geothermalis, which is only the second extremely radiation- and desiccation-resistant bacterium to be sequenced.

How The Zebrafish Gets His Stripe:

Scientists have discovered how the zebrafish (Danio rerio) develops one of its four stripes of pigment cells. Their findings add to the growing list of tasks carried out by an important molecule that is involved in the arrangement of everything from nerve cells to reproductive cells in the developing embryo.

Solving A Dragonfly Flight Mystery:

Dragonflies adjust their wing motion while hovering to conserve energy, according to a Cornell University study of the insect’s flight mechanics. The revelation contradicts previous speculation that the change in wing motion served to enhance vertical lift.

Mice Teeth Explain The Troubles With Human Wisdom Teeth:

During evolution, many of a species’ properties are shaped by ecological interactions. This is readily evident in mammalian teeth, whose many features closely reflect what each species eats. However, for a long time scientists have suspected that genetic and developmental interactions may also influence species-specific properties. Now, researchers at the University of Helsinki’s Institute of Biotechnology show how development affects the evolution of teeth, and have devised a simple developmental model to predict aspects of teeth across many species. The results were published in Nature.

Vitamin C Is Essential For Plant Growth:

Scientists from the University of Exeter and Shimane University in Japan have proved for the first time that vitamin C is essential for plant growth. This discovery could have implications for agriculture and for the production of vitamin C dietary supplements.

New Animal And Plant Species Found In Vietnam:

World Wildlife Fund scientists have just announced the discovery of 11 new animal and plant species in a remote area in central Vietnam. They say this underscores the importance of conservation efforts in the ancient tropical forests of the region.

Primate Sperm Competition: Speed Matters:

Researchers at UC San Diego and UC Irvine have found evidence that supports the theory that reproductive competition during the evolution of primate species has occurred at the level of sperm cell motility.

Clever Plants ‘Chat’ Over Their Own Network:

Recent research from Vidi researcher Josef Stuefer at the Radboud University Nijmegen reveals that plants have their own chat systems that they can use to warn each other.

You Can Teach An Old Dog New Tricks — With The Right Diet:

These supplements, acetyl-l-carnitine and alpha lipoic acid, are continuing to be studied in work with humans, and scientists believe they may provide a new approach to the neurodegeneration and cognitive decline common with aging.

Amazon Forest Shows Unexpected Resiliency During Drought:

Drought-stricken regions of the Amazon forest grew particularly vigorously during the 2005 drought, according to new research.

New Species Of Bacteria Feeds On Natural Gas:

A German-American research team of biologists and geochemists has discovered hitherto unknown anaerobic bacteria in marine sediments which need only propane or butane for growth, as recently reported by the scientific journal “Nature.”

Rare Albino Ratfish Has Eerie, Silvery Sheen:

A ghostly, mutant ratfish caught off Whidbey Island in Washington state is the only completely albino fish ever seen by both the curator of the University of Washington’s 7.2 million-specimen fish collection and a fish and wildlife biologist with more than 20 years of sampling fish in Puget Sound.

Could Iron Fertilization Of Oceans Combat Global Warming?:

Several times over the past century, scientists and environmental engineers have proposed spreading slurries of dissolved iron into the oceans in order to “fertilize” the waters and promote vast blooms of marine plants (phytoplankton). Phytoplankton consume carbon dioxide as they grow, and this growth can be stimulated in certain ocean basins by the addition of iron, a necessary micronutrient.

Steve Irwin’s last paper is not the only exciting article to appear on PLoS ONE today – there are 40 more, and here are a few I am excited about – a veritable embarassment of riches! When am I ever going to find time to read them all!
Oxytocin in the Circadian Timing of Birth (hey, it’s by Erik Herzog, so you know I’ll blog about this paper in a separate post later):

Very little is known about the molecular components that determine the timing for birth in mammals. This study compares the timing of births between mice with and without the chemical oxytocin (OT) when exposed to shifts in the light cycle. The results show that OT-deficient mice give birth at random times throughout the light cycle, while mice with OT maintain a normal clustered birth profile, thus suggesting that oxytocin is necessary in the timing of birth.

A Visual Pathway Links Brain Structures Active during Magnetic Compass Orientation in Migratory Birds:

The magnetic compass of migratory birds has been suggested to be light-dependent. Retinal cryptochrome-expressing neurons and a forebrain region, “Cluster N”, show high neuronal activity when night-migratory songbirds perform magnetic compass orientation. By combining neuronal tracing with behavioral experiments leading to sensory-driven gene expression of the neuronal activity marker ZENK during magnetic compass orientation, we demonstrate a functional neuronal connection between the retinal neurons and Cluster N via the visual thalamus. Thus, the two areas of the central nervous system being most active during magnetic compass orientation are part of an ascending visual processing stream, the thalamofugal pathway. Furthermore, Cluster N seems to be a specialized part of the visual wulst. These findings strongly support the hypothesis that migratory birds use their visual system to perceive the reference compass direction of the geomagnetic field and that migratory birds “see” the reference compass direction provided by the geomagnetic field.

Do Individual Females Differ Intrinsically in Their Propensity to Engage in Extra-Pair Copulations?:

While many studies have investigated the occurrence of extra-pair paternity in wild populations of birds, we still know surprisingly little about whether individual females differ intrinsically in their principal readiness to copulate, and to what extent this readiness is affected by male attractiveness.
To address this question I used captive zebra finches (Taeniopygia guttata) as a model system. I first measured female readiness to copulate when courted by a male for the first time in life. Second, I conducted choice-chamber experiments to assess the mating preferences of individual females prior to pair formation. I then paired females socially with a non-desired mate and once they had formed a stable pair bond, I observed the inclination of these females to engage in extra-pair copulations with various males. Females showing a high readiness to copulate when courted by a male for the first time in life were much more likely to engage in extra-pair copulations later in life than others. Male attractiveness, as measured in choice tests, was a useful predictor of whether females engaged in extra-pair copulations with these males, but, surprisingly, the attractiveness of a female’s social partner had no effect on her fidelity. However, it remained unclear what made some males more attractive than others. Contrary to a widespread but rarely tested hypothesis, females did not preferentially copulate with males having a redder beak or singing at a higher rate. Rather it seemed that song rate was a confounding factor in choice-chamber experiments: song attracted the female’s attention but did not increase the male’s attractiveness as a copulation partner.
Intrinsic variation in female readiness to copulate as well as variation in the attractiveness of the extra-pair male but not the social partner decided the outcome of extra-pair encounters.

Evolution of Female Preference for Younger Males:

Previous theoretical work has suggested that females should prefer to mate with older males, as older males should have higher fitness than the average fitness of the cohort into which they were born. However, studies in humans and model organisms have shown that as males age, they accumulate deleterious mutations in their germ-line at an ever-increasing rate, thereby reducing the quality of genes passed on to the next generation. Thus, older males may produce relatively poor-quality offspring. To better understand how male age influences female mate preference and offspring quality, we used a genetic algorithm model to study the effect of age-related increases in male genetic load on female mate preference. When we incorporate age-related increases in mutation load in males into our model, we find that females evolve a preference for younger males. Females in this model could determine a male’s age, but not his inherited genotype nor his mutation load. Nevertheless, females evolved age-preferences that led them to mate with males that had low mutation loads, but showed no preference for males with respect to their somatic quality. These results suggest that germ-line quality, rather than somatic quality, should be the focus of female preference in good genes models.

Causal Inference in Multisensory Perception:

Perceptual events derive their significance to an animal from their meaning about the world, that is from the information they carry about their causes. The brain should thus be able to efficiently infer the causes underlying our sensory events. Here we use multisensory cue combination to study causal inference in perception. We formulate an ideal-observer model that infers whether two sensory cues originate from the same location and that also estimates their location(s). This model accurately predicts the nonlinear integration of cues by human subjects in two auditory-visual localization tasks. The results show that indeed humans can efficiently infer the causal structure as well as the location of causes. By combining insights from the study of causal inference with the ideal-observer approach to sensory cue combination, we show that the capacity to infer causal structure is not limited to conscious, high-level cognition; it is also performed continually and effortlessly in perception.

Antagonistic Bacterial Interactions Help Shape Host-Symbiont Dynamics within the Fungus-Growing Ant-Microbe Mutualism:

Conflict within mutually beneficial associations is predicted to destabilize relationships, and theoretical and empirical work exploring this has provided significant insight into the dynamics of cooperative interactions. Within mutualistic associations, the expression and regulation of conflict is likely more complex than in intraspecific cooperative relationship, because of the potential presence of: i) multiple genotypes of microbial species associated with individual hosts, ii) multiple species of symbiotic lineages forming cooperative partner pairings, and iii) additional symbiont lineages. Here we explore complexity of conflict expression within the ancient and coevolved mutualistic association between attine ants, their fungal cultivar, and actinomycetous bacteria (Pseudonocardia). Specifically, we examine conflict between the ants and their Pseudonocardia symbionts maintained to derive antibiotics against parasitic microfungi (Escovopsis) infecting the ants’ fungus garden. Symbiont assays pairing isolates of Pseudonocardia spp. associated with fungus-growing ants spanning the phylogenetic diversity of the mutualism revealed that antagonism between strains is common. In contrast, antagonism was substantially less common between more closely related bacteria associated with Acromyrmex leaf-cutting ants. In both experiments, the observed variation in antagonism across pairings was primarily due to the inhibitory capabilities and susceptibility of individual strains, but also the phylogenetic relationships between the ant host of the symbionts, as well as the pair-wise genetic distances between strains. The presence of antagonism throughout the phylogenetic diversity of Pseudonocardia symbionts indicates that these reactions likely have shaped the symbiosis from its origin. Antagonism is expected to prevent novel strains from invading colonies, enforcing single-strain rearing within individual ant colonies. While this may align ant-actinomycete interests in the bipartite association, the presence of single strains of Pseudonocardia within colonies may not be in the best interest of the ants, because increasing the diversity of bacteria, and thereby antibiotic diversity, would help the ant-fungus mutualism deal with the specialized parasites.

Do Haematophagous Bugs Assess Skin Surface Temperature to Detect Blood Vessels?:

It is known that some blood-sucking insects have the ability to reach vessels under the host skin with their mouthparts to feed blood from inside them. However, the process by which they locate these vessels remains largely unknown. Less than 5% of the skin is occupied by blood vessels and thus, it is not likely that insects rely on a “random search strategy”, since it would increase the probability of being killed by their hosts. Indeed, heterogeneities along the skin surface might offer exploitable information for guiding insect’s bites.
We tested whether the bug Rhodnius prolixus can evaluate temperature discontinuities along the body surface in order to locate vessels before piercing the host skin. When placed over a rabbit ear, the bug’s first bites were mostly directed towards the main vessels. When insects were confronted to artificial linear heat sources presenting a temperature gradient against the background, most bites were directly addressed to the warmer linear source, notwithstanding the temperature of both, the source and the background. Finally, tests performed using uni- and bilaterally antennectomized insects revealed that the bilateral integration of thermal inputs from both antennae is necessary for precisely directing bites.
R. prolixus may be able to exploit the temperature differences observed over the skin surface to locate blood vessles. Bugs bite the warmest targets regardless of the target/background temperatures, suggesting that they do not bite choosing a preferred temperature, but select temperature discontinuities along the skin. This strategy seems to be an efficient one for finding blood vessels within a wide temperature range, allowing finding them on different hosts, as well as on different areas of the host body. Our study also adds new insight about the use of antennal thermal inputs by blood sucking bugs.

Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks:

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to resistance; and strengthen the case for a role in survival of systems involved in manganese and iron homeostasis.

Also:
Lactate, Fructose and Glucose Oxidation Profiles in Sports Drinks and the Effect on Exercise Performance
Cultural Diversity, Economic Development and Societal Instability
Stochastic Species Turnover and Stable Coexistence in a Species-Rich, Fire-Prone Plant Community
Global Patterns of City Size Distributions and Their Fundamental Drivers
Children’s Health Status: Examining the Associations among Income Poverty, Material Hardship, and Parental Factors
As always: read, rate, comment, annotate, use and reuse and, if you blog about the PLoS ONE papers, try to use the correct form of the URL in order to generate a trackback.

A bunch of new articles got published in PLoS Medicine and PLoS Biology yesterday. Here are my two picks, and you go and check the rest:
Brain Dynamics Underlying the Nonlinear Threshold for Access to Consciousness:

Understanding the neural mechanisms that distinguish between conscious and nonconscious processes is a crucial issue in cognitive neuroscience. In this study, we focused on the transition that causes a visual stimulus to cross the threshold to consciousness, i.e., visibility. We used a backward masking paradigm in which the visibility of a briefly presented stimulus (the “target”) is reduced by a second stimulus (the “mask”) presented shortly after this first stimulus. (Human participants report the visibility of the target.) When the delay between target and mask stimuli exceeds a threshold value, the masked stimulus becomes visible. Below this threshold, it remains nonvisible. During the task, we recorded electric brain activity from the scalp and reconstructed the cortical sources corresponding to this activity. Conscious perception of masked stimuli corresponded to activity in a broadly distributed fronto-parieto-temporal network, occurring from about 300 ms after stimulus presentation. We conclude that this late stage, which could be clearly separated from earlier neural events associated with subliminal processing and mask-target interactions, can be regarded as a marker of consciousness.

The Absolute Risk of Venous Thrombosis after Air Travel: A Cohort Study of 8,755 Employees of International Organisations:

Background.
Blood normally flows smoothly throughout the human body, supplying the brain and other vital organs with oxygen and nutrients. When an injury occurs, proteins called clotting factors make the blood gel or coagulate at the injury site. The resultant blood clot (thrombus) plugs the wound and prevents blood loss. Sometimes, however, a thrombus forms inside an uninjured blood vessel and partly or completely blocks the blood flow. A clot inside one of the veins (vessels that take blood to the heart) deep within the body is called a deep vein thrombosis (DVT). Symptoms of DVT (which usually occurs in the deep veins of the leg) include pain, swelling, and redness in one leg. DVT is usually treated with heparin and warfarin, two anticoagulant drugs that stop the blood clot growing. If left untreated, part of the clot (an embolus) can break off and travel to the lungs, where it can cause a life-threatening condition called pulmonary embolism (PE). Fortunately, DVT and PE are rare but having an inherited blood clotting disorder, taking an oral contraceptive, and some types of surgery are all risk factors for them. In addition, long-haul plane travel increases the risk of DVT and PE, known collectively as venous thrombosis (VT) 2- to 4-fold, in part because the enforced immobilization during flights slows down blood flow.
Why Was This Study Done?
Although the link between air travel and VT was first noticed in the 1950s, exactly how many people will develop DVT and PE (the absolute risk of developing VT) after a long flight remains unknown. This information is needed so that travelers can be given advice about their actual risk and can make informed decisions about trying to reduce that risk by, for example, taking small doses of anticoagulant medicine before a flight. In this study, the researchers have determined the absolute risk of VT during and after long-haul air travel in a large group of business travelers.
What Did the Researchers Do and Find?
The researchers enrolled almost 9,000 employees from several international companies and organizations and followed them for an average of 4.4 years. The details of flights taken by each employee were obtained from company records, and employees completed a Web-based questionnaire about whether they had developed VT and what risk factors they had for the condition. Out of 53 thrombi that occurred during the study, 22 occurred within eight weeks of a long-haul flight (a flight of more than four hours). From this and data on the total time employees spent on long-haul flights, the researchers calculated that these flights tripled the risk of developing VT, and that the absolute risk (the probability of something occurring in a certain time period) of a VT occurring shortly after such travel was one event per 4,656 flights. They also calculated that the risk of VT was increased by exposure to more flights during a short period and to longer flights and was greatest in the first two weeks after a flight. In addition, the risk of VT was particularly high in young employees, women taking oral contraceptives, and people who were short, tall or overweight.
What Do These Findings Mean?
The main finding of this study is that the absolute risk of VT after of a long-haul flight is low–only one passenger out of nearly 5,000 is likely to develop VT because of flying. However, the study included only healthy people without previous VT whose average age was 40 years, so the absolute risk of VT after long-haul flights might be higher in the general traveling population. Even so, this finding strongly suggests that prophylactic (preventative) use of anticoagulants by all long-haul travelers may not be justified because these drugs have potentially dangerous side effects (for example, they can cause uncontrolled bleeding). Subgroups of travelers with additional risk factors for VT might, however, benefit from the use of this and other prophylactic measures, but randomized trials are needed to find out who would benefit most from which prophylactic measure.

If You Want More Babies, Find A Man With A Deep Voice:

Men who have lower-pitched voices have more children than do men with high-pitched voices, researchers have found. And their study suggests that for reproductive-minded women, mate selection favours men with low-pitched voices.

Spaceflight Can Change Bacteria Into More Infectious Pathogens:

Space flight has been shown to have a profound impact on human physiology as the body adapts to zero gravity environments.

Making Bicycles That Balance Better:

For nearly 150 years, scientists have been puzzled by the bicycle. How on earth is it possible that a moving bicycle can, all by itself, be so stable? Researchers of the Delft University of Technology (TU Delft), working with colleagues from Cornell University and the University of Nottingham, UK, believe they have now found the ultimate model of the bicycle.

How Does The Brain Develop During Embryogenesis?:

One of the great questions of neurobiology, how the brain is built up during embryonic development, could be resolved by a young French scientist in an award winning project organised by the European Science Foundation (ESF) and the European Heads of Research Councils (EuroHORCS).

Controlling For Size May Also Prevent Cancer:

Scientists at Johns Hopkins recently discovered that a chemical chain reaction that controls organ size in animals ranging from insects to humans could mean the difference between normal growth and cancer.

New Dinosaur Species Found In Montana:

A dinosaur skeleton found 24 years ago near Choteau has finally been identified as a new species that links North American dinosaurs with Asian dinosaurs. The dinosaur would have weighed 30 to 40 pounds, walked on two feet and stood about three feet tall. The fossil came from sediment that’s about 80 million years old.

Hormone Therapy Boosts Sexual Interest But Not Memory, Study Suggests:

Hormone therapy in early post-menopause increases sexual interest, but does not improve memory, according to a new study. “Contrary to what we predicted, hormone therapy did not have a positive affect on memory performance in younger mid-life women,” said Pauline Maki, associate professor of psychiatry and psychology at the University of Illinois at Chicago, who led the study.