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Ocean science: The origins of a climate oscillation

Nature - Wed, 05/27/2015 - 00:00

Ocean science: The origins of a climate oscillation

Nature 521, 7553 (2015). doi:10.1038/521428a

Authors: Sergey K. Gulev & Mojib Latif

An index of water-circulation strength in the North Atlantic Ocean has been derived from sea-level measurements. This provides fresh evidence of the ocean's leading role in multidecadal climate variability. See Letter p.508

Categories: Literature

Cancer metabolism: A waste of insulin interference

Nature - Wed, 05/27/2015 - 00:00

Cancer metabolism: A waste of insulin interference

Nature 521, 7553 (2015). doi:10.1038/521430a

Authors: Erwin F. Wagner & Michele Petruzzelli

Many people with cancer die from a wasting disorder called cancer-associated cachexia. Two studies in fruit flies show that inhibition of insulin signalling causes cachexia-like organ wasting.

Categories: Literature

Palaeoanthropology: The middle Pliocene gets crowded

Nature - Wed, 05/27/2015 - 00:00

Palaeoanthropology: The middle Pliocene gets crowded

Nature 521, 7553 (2015). doi:10.1038/521432a

Authors: Fred Spoor

New hominin fossils discovered in Ethiopia, dated to between 3.5 million and 3.3 million years ago, suggest that species diversity may have been as high during early human evolution as in later periods. See Article p.483

Categories: Literature

New species from Ethiopia further expands Middle Pliocene hominin diversity

Nature - Wed, 05/27/2015 - 00:00

New species from Ethiopia further expands Middle Pliocene hominin diversity

Nature 521, 7553 (2015). doi:10.1038/nature14448

Authors: Yohannes Haile-Selassie, Luis Gibert, Stephanie M. Melillo, Timothy M. Ryan, Mulugeta Alene, Alan Deino, Naomi E. Levin, Gary Scott & Beverly Z. Saylor

Middle Pliocene hominin species diversity has been a subject of debate over the past two decades, particularly after the naming of Australopithecus bahrelghazali and Kenyanthropus platyops in addition to the well-known species Australopithecus afarensis. Further analyses continue to support the proposal that

Categories: Literature

A kiloparsec-scale internal shock collision in the jet of a nearby radio galaxy

Nature - Wed, 05/27/2015 - 00:00

A kiloparsec-scale internal shock collision in the jet of a nearby radio galaxy

Nature 521, 7553 (2015). doi:10.1038/nature14481

Authors: Eileen T. Meyer, Markos Georganopoulos, William B. Sparks, Eric Perlman, Roeland P. van der Marel, Jay Anderson, Sangmo Tony Sohn, John Biretta, Colin Norman & Marco Chiaberge

Jets of highly energized plasma with relativistic velocities are associated with black holes ranging in mass from a few times that of the Sun to the billion-solar-mass black holes at the centres of galaxies. A popular but unconfirmed hypothesis to explain how the plasma is energized is the ‘internal shock model’, in which the relativistic flow is unsteady. Faster components in the jet catch up to and collide with slower ones, leading to internal shocks that accelerate particles and generate magnetic fields. This mechanism can explain the variable, high-energy emission from a diverse set of objects, with the best indirect evidence being the unseen fast relativistic flow inferred to energize slower components in X-ray binary jets. Mapping of the kinematic profiles in resolved jets has revealed precessing and helical patterns in X-ray binaries, apparent superluminal motions, and the ejection of knots (bright components) from standing shocks in the jets of active galaxies. Observations revealing the structure and evolution of an internal shock in action have, however, remained elusive, hindering measurement of the physical parameters and ultimate efficiency of the mechanism. Here we report observations of a collision between two knots in the jet of nearby radio galaxy 3C 264. A bright knot with an apparent speed of (7.0 ± 0.8)c, where c is the speed of light in a vacuum, is in the incipient stages of a collision with a slower-moving knot of speed (1.8 ± 0.5)c just downstream, resulting in brightening of both knots—as seen in the most recent epoch of imaging.

Categories: Literature

Extreme ultraviolet high-harmonic spectroscopy of solids

Nature - Wed, 05/27/2015 - 00:00

Extreme ultraviolet high-harmonic spectroscopy of solids

Nature 521, 7553 (2015). doi:10.1038/nature14456

Authors: T. T. Luu, M. Garg, S. Yu. Kruchinin, A. Moulet, M. Th. Hassan & E. Goulielmakis

Extreme ultraviolet (EUV) high-harmonic radiation emerging from laser-driven atoms, molecules or plasmas underlies powerful attosecond spectroscopy techniques and provides insight into fundamental structural and dynamic properties of matter. The advancement of these spectroscopy techniques to study strong-field electron dynamics in condensed matter calls for the generation and manipulation of EUV radiation in bulk solids, but this capability has remained beyond the reach of optical sciences. Recent experiments and theoretical predictions paved the way to strong-field physics in solids by demonstrating the generation and optical control of deep ultraviolet radiation in bulk semiconductors, driven by femtosecond mid-infrared fields or the coherent up-conversion of terahertz fields to multi-octave spectra in the mid-infrared and optical frequencies. Here we demonstrate that thin films of SiO2 exposed to intense, few-cycle to sub-cycle pulses give rise to wideband coherent EUV radiation extending in energy to about 40 electronvolts. Our study indicates the association of the emitted EUV radiation with intraband currents of multi-petahertz frequency, induced in the lowest conduction band of SiO2. To demonstrate the applicability of high-harmonic spectroscopy to solids, we exploit the EUV spectra to gain access to fine details of the energy dispersion profile of the conduction band that are as yet inaccessible by photoemission spectroscopy in wide-bandgap dielectrics. In addition, we use the EUV spectra to trace the attosecond control of the intraband electron motion induced by synthesized optical transients. Our work advances lightwave electronics in condensed matter into the realm of multi-petahertz frequencies and their attosecond control, and marks the advent of solid-state EUV photonics.

Categories: Literature

Robots that can adapt like animals

Nature - Wed, 05/27/2015 - 00:00

Robots that can adapt like animals

Nature 521, 7553 (2015). doi:10.1038/nature14422

Authors: Antoine Cully, Jeff Clune, Danesh Tarapore & Jean-Baptiste Mouret

Robots have transformed many industries, most notably manufacturing, and have the power to deliver tremendous benefits to society, such as in search and rescue, disaster response, health care and transportation. They are also invaluable tools for scientific exploration in environments inaccessible to humans, from distant planets to deep oceans. A major obstacle to their widespread adoption in more complex environments outside factories is their fragility. Whereas animals can quickly adapt to injuries, current robots cannot ‘think outside the box’ to find a compensatory behaviour when they are damaged: they are limited to their pre-specified self-sensing abilities, can diagnose only anticipated failure modes, and require a pre-programmed contingency plan for every type of potential damage, an impracticality for complex robots. A promising approach to reducing robot fragility involves having robots learn appropriate behaviours in response to damage, but current techniques are slow even with small, constrained search spaces. Here we introduce an intelligent trial-and-error algorithm that allows robots to adapt to damage in less than two minutes in large search spaces without requiring self-diagnosis or pre-specified contingency plans. Before the robot is deployed, it uses a novel technique to create a detailed map of the space of high-performing behaviours. This map represents the robot’s prior knowledge about what behaviours it can perform and their value. When the robot is damaged, it uses this prior knowledge to guide a trial-and-error learning algorithm that conducts intelligent experiments to rapidly discover a behaviour that compensates for the damage. Experiments reveal successful adaptations for a legged robot injured in five different ways, including damaged, broken, and missing legs, and for a robotic arm with joints broken in 14 different ways. This new algorithm will enable more robust, effective, autonomous robots, and may shed light on the principles that animals use to adapt to injury.

Categories: Literature

Ocean impact on decadal Atlantic climate variability revealed by sea-level observations

Nature - Wed, 05/27/2015 - 00:00

Ocean impact on decadal Atlantic climate variability revealed by sea-level observations

Nature 521, 7553 (2015). doi:10.1038/nature14491

Authors: Gerard D. McCarthy, Ivan D. Haigh, Joël J.-M. Hirschi, Jeremy P. Grist & David A. Smeed

Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall, European summer precipitation, Atlantic hurricanes and variations in global temperatures. It is widely believed that ocean circulation drives the phase changes of the AMO by controlling ocean heat content. However, there are no direct observations of ocean circulation of sufficient length to support this, leading to questions about whether the AMO is controlled from another source. Here we provide observational evidence of the widely hypothesized link between ocean circulation and the AMO. We take a new approach, using sea level along the east coast of the United States to estimate ocean circulation on decadal timescales. We show that ocean circulation responds to the first mode of Atlantic atmospheric forcing, the North Atlantic Oscillation, through circulation changes between the subtropical and subpolar gyres—the intergyre region. These circulation changes affect the decadal evolution of North Atlantic heat content and, consequently, the phases of the AMO. The Atlantic overturning circulation is declining and the AMO is moving to a negative phase. This may offer a brief respite from the persistent rise of global temperatures, but in the coupled system we describe, there are compensating effects. In this case, the negative AMO is associated with a continued acceleration of sea-level rise along the northeast coast of the United States.

Categories: Literature

Officials Uncover “Mass Graves” Of Illegal Timber in Malaysia Forest Reserve

Yale Environment 360 - Tue, 05/26/2015 - 11:02

Malaysian authorities have uncovered timber “mass graves” where illegal loggers attempted to conceal valuable timber

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Muhaizan Yahya/nst.com A "mass grave" containing illegally logged timber. following a government crackdown on unlawful logging that started in February. The sites, located in the Belum-Temengor forest reserve, were revealed after the recent excavation of patches of land roughly the size of football fields, beneath which an estimated two stories of felled trees were stacked. “We believe that about 400 tons of logs worth more than RM1 million ($250,000 USD) were buried at the three locations and the culprits are waiting for the right time to dig them out and sell them,” says Anuar Mohd Noh, assistant commissioner for the Malaysian Anti-Corruption Commission (MACC), which conducted a joint operation with the country’s forestry department to track down illicit logging activities.
Read more.

Categories: Environmental News

Surge in Renewables Remakes California’s Energy Landscape

Yale Environment 360 - Tue, 05/26/2015 - 07:31

Thanks to favorable geography, innovative government policies, and businesses that see the benefits of clean energy investments, California is closing in on its goal of generating a third of its electricity from renewables by 2020. BY CHERYL KATZ

Categories: Environmental News

Trading places

Nature - Tue, 05/26/2015 - 00:00

Trading places

Nature 521, 7553 (2015). doi:10.1038/521393a

Scientists have a valuable part to play in clarifying the impacts of a proposed trade treaty between the United States and Europe.

Categories: Literature

Wakey wakey

Nature - Tue, 05/26/2015 - 00:00

Wakey wakey

Nature 521, 7553 (2015). doi:10.1038/521394a

Sleeping-beauty papers offer hope that authors of uncited works are in good company.

Categories: Literature

Giant international trade treaties centre on science

Nature - Tue, 05/26/2015 - 00:00

Giant international trade treaties centre on science

Nature 521, 7553 (2015). http://www.nature.com/doifinder/10.1038/521401a

Author: Daniel Cressey

Proposed deals have potential to boost research, but also to weaken health and environmental protections.

Categories: Literature

Animal behaviour: Inside the cunning, caring and greedy minds of fish

Nature - Tue, 05/26/2015 - 00:00

Animal behaviour: Inside the cunning, caring and greedy minds of fish

Nature 521, 7553 (2015). http://www.nature.com/doifinder/10.1038/521412a

Author: Alison Abbott

By revealing that fish cooperate, cheat and punish, Redouan Bshary has challenged ideas about brain evolution.

Categories: Literature

Many Trees in Southeast U.S. Closely Related to Tree Species in Asia

Yale Environment 360 - Fri, 05/22/2015 - 09:03

DNA studies show that more than half the trees and shrubs in southern Appalachia can trace their ancestry to eastern Asia.

A flowering dogwood tree Based on molecular studies of more than 250 species of trees and shrubs from Georgia to Virginia, researchers at Duke University found close ties between East Asian species, such as dogwoods, and species in the southeastern U.S. Forests throughout the northern hemisphere were joined together by the supercontinent Laurasia as recently as 180 million years ago. Then, as the great northern land mass broke into continents, eras of glaciation wiped out various tree species. Forest remnants hung on in China, Japan, small parts of Europe, and Appalachia, which explains the similarity in tree species. The research was published in the American Journal of Botany.

Categories: Environmental News

Interview: A Grassroots Effort to Save Africa’s Most Endangered Ape

Yale Environment 360 - Thu, 05/21/2015 - 07:33

The Cross River gorilla population, with fewer than 300 individuals, has been pushed to the brink of extinction in equatorial Inaoyom Imong Africa. At the center of the fight to save this beleaguered ape population is Nigerian scientist Inaoyom Imong, who comes from the region and knows its forests — and its people — intimately. In a Yale e360 interview, Imong describes the various pressures that have reduced populations of this gorilla subspecies and explains how a few thousand people living in rural Nigeria and Cameroon hold the key to saving this magnificent ape.
Read the interview.

Categories: Environmental News

Artificial-windpipe surgeon committed misconduct

Nature - Thu, 05/21/2015 - 00:00

Artificial-windpipe surgeon committed misconduct

Nature 521, 7553 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.17605

Author: David Cyranoski

Papers authored by Paolo Macchiarini misrepresented success of pioneering procedure.

Categories: Literature

Many Wind Turbines Being Installed in Critical Bird Habitat, Group Says

Yale Environment 360 - Wed, 05/20/2015 - 11:28

More than 30,000 wind turbines in the U.S. have been installed in areas critical to the survival of federally protected birds and

Whooping crane an additional 50,000 turbines are planned for similar areas, according to the advocacy group American Bird Conservancy (ABC). Those figures include 24,000 turbines in the migration corridor of the rare whooping crane and nearly 3,000 turbines in breeding strongholds for greater sage grouse, a species that has already declined by up to 80 percent in recent decades due to habitat loss, ABC says. The group is asking the federal government to regulate the wind industry with regard to its impacts on birds. Areas of "critical importance," where federally protected birds face the highest levels of risk, comprise just 9 percent of the land area of the U.S. and should be avoided in wind development, ABC says.

Categories: Environmental News

Potential flaws in genomics paper scrutinized on Twitter

Nature - Wed, 05/20/2015 - 00:00

Potential flaws in genomics paper scrutinized on Twitter

Nature 521, 7553 (2015). doi:10.1038/521397f

Author: Chris Woolston

Reanalysis of a study that compared gene expression in mice and humans tests social media as a forum for discussing research results.

Categories: Literature

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