Science news

• U.S. to propose U.N. arms embargo on South Sudan, sanctions

  17-11-2016 23:26
  By Michelle Nichols UNITED NATIONS (Reuters) - The United States said on Thursday that in the coming days it would circulate to the 15-member United Nations Security Council a draft resolution to impose an arms embargo on South Sudan and further targeted sanctions amid warnings of possible genocide. Political rivalry between South Sudan's President Salva Kiir, an ethnic Dinka, and his former deputy Riek Machar, a Nuer, led to civil war in 2013 that has often followed ethnic lines. The pair signe
  
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• Peggy Whitson: Oldest woman in space blasts off to ISS

  17-11-2016 23:16 via bbc.co.uk
  
  Nasa astronaut Peggy Whitson, 56, breaks more records as she heads to the ISS for the third time.
  
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• Drought in Northeast US expected to persist through February

  17-11-2016 22:49
  
  CONCORD, N.H. (AP) — The long-running drought in much of the Northeastern United States is expected to persist through the winter.
  
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• Countries unite to defy Trump climate threat

  17-11-2016 22:27 via bbc.co.uk
  
  Delegates from more than 190 countries meeting in Marrakech issue a united call for action on climate change.
  
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• Message to Trump? Countries say climate fight 'irreversible'

  17-11-2016 22:16
  
  MARRAKECH, Morocco (AP) — Government delegates meeting for U.N. climate talks reiterated their commitment to the Paris Agreement with a proclamation Thursday saying climate action is "irreversible," the buzzword at the two-week conference after the uncertainty caused by the U.S. election.
  
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• Dino-Killing Asteroid May Have Punctured Earth's Crust

  17-11-2016 22:15
  
  After analyzing the crater from the cosmic impact that ended the age of dinosaurs, scientists now say the object that smacked into the planet may have punched nearly all the way through Earth's crust, according to a new study.
  
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• The secret to a perfect cup of coffee could be math

  17-11-2016 22:11 via cbc.ca
  
  Irish researchers have devised a mathematical model for drip coffee, hoping to unlock the secret to the smoothest, most predicable, and most efficient brew.
  
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• Foie gras, saxophone blast into space with astronauts

  17-11-2016 22:02
  
  A trio of astronauts soared into orbit Friday bound for the International Space Station, with their Soyuz spacecraft delivering some fancy French food, a saxophone and the future female commander.
  
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• Why is food allergy increasing? Skin might be involved

  17-11-2016 21:55
  Early exposure to a food allergen through broken skin might prompt the development of food allergy. This theory gained further support from a recent study that found increased prevalence of food allergy if a child had skin infection or eczema in the first year of life.
  
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• Legal and ethical factors that affect NFL players’ health

  17-11-2016 21:55
  A newly released on analysis performed over two years outlines key recommendations to improve structural, ethical and legal factors that affect the health of NFL players.
  
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• Rocket carrying crew of 3 blasts off for Int'l Space Station

  17-11-2016 21:46
  
  BAIKONUR, Kazakhstan (AP) — A Soyuz rocket carrying a veteran American astronaut, a French newcomer and a Russian cosmonaut blasted off for the International Space Station on Friday.
  
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• Twitter CEO apologizes for allowing white supremacist ad

  17-11-2016 21:43 via cbc.ca
  
  Twitter's Chief Executive Jack Dorsey apologized on Thursday after the microblogging service let through an ad promoting a white supremacist group.
  
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• [Working Life] Selling out science?

  17-11-2016 21:37
  Author: Kevin F. Boehnke
  
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• [This Week in Science] Watching it all fall apart

  17-11-2016 21:37
  Author: Marc S. Lavine
  
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• [This Week in Science] Toward malaria eradication

  17-11-2016 21:37
  Author: Katrina L. Kelner
  
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• [This Week in Science] Tau phosphorylation—not all bad

  17-11-2016 21:37
  Author: Stella M. Hurtley
  
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• [This Week in Science] Tandem perovskite cells

  17-11-2016 21:37
  Author: Phil Szuromi
  
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• [This Week in Science] Sacral neurons reassigned

  17-11-2016 21:37
  Author: Pamela J. Hines
  
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• [This Week in Science] Pluses and minuses of BTX behavior

  17-11-2016 21:37
  Author: Jake Yeston
  
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• [This Week in Science] Optimizing designer metabolisms in vitro

  17-11-2016 21:37
  Author: Nicholas S. Wigginton
  
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• [This Week in Science] Metabolite channeling by a dynamic metabolon

  17-11-2016 21:37
  Author: Pamela J. Hines
  
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• [This Week in Science] Integrated quantum nanophotonics

  17-11-2016 21:37
  Author: Ian S. Osborne
  
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• [This Week in Science] Faster light adaptation improves productivity

  17-11-2016 21:37
  Author: Pamela J. Hines
  
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• [This Week in Science] Exhausting autoimmunity

  17-11-2016 21:37
  Author: Angela Colmone
  
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• [This Week in Science] Drilling into Chicxulub's formation

  17-11-2016 21:37
  Author: Brent Grocholski
  
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• [This Week in Science] Directing traffic with patterns

  17-11-2016 21:37
  Author: Marc S. Lavine
  
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• [This Week in Science] Combining heat and light responses

  17-11-2016 21:37
  Author: Pamela J. Hines
  
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• [This Week in Science] Combating parasitic DNA by methylation

  17-11-2016 21:37
  Author: Guy Riddihough
  
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• [This Week in Science] CO takes the lead to make β-lactam rings

  17-11-2016 21:37
  Author: Jake Yeston
  
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• [This Week in Science] A volcanic end to an earthquake

  17-11-2016 21:37
  Author: Brent Grocholski
  
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• [This Week in Science] A kinase makes its own inhibitor

  17-11-2016 21:37
  Author: Nancy R. Gough
  
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• [This Week in Science] A clear approach to nanophotonics

  17-11-2016 21:37
  Author: Ian S. Osborne
  
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• [Review] Optically resonant dielectric nanostructures

  17-11-2016 21:37
  Rapid progress in nanophotonics is driven by the ability of optically resonant nanostructures to enhance near-field effects controlling far-field scattering through intermodal interference. A majority of such effects are usually associated with plasmonic nanostructures. Recently, a new branch of nanophotonics has emerged that seeks to manipulate the strong, optically induced electric and magnetic Mie resonances in dielectric nanoparticles with high refractive index. In the design of optical nano
  
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• [Research Article] Improving photosynthesis and crop productivity by accelerating recovery from photoprotection

  17-11-2016 21:37
  Crop leaves in full sunlight dissipate damaging excess absorbed light energy as heat. When sunlit leaves are shaded by clouds or other leaves, this protective dissipation continues for many minutes and reduces photosynthesis. Calculations have shown that this could cost field crops up to 20% of their potential yield. Here, we describe the bioengineering of an accelerated response to natural shading events in Nicotiana (tobacco), resulting in increased leaf carbon dioxide uptake and plant dry mat
  
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• [Research Article] An integrated diamond nanophotonics platform for quantum-optical networks

  17-11-2016 21:37
  Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate an integrated platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and ob
  
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• [Research Article] A general catalytic β-C–H carbonylation of aliphatic amines to β-lactams

  17-11-2016 21:37
  Methods for the synthesis and functionalization of amines are intrinsically important to a variety of chemical applications. We present a general carbon-hydrogen bond activation process that combines readily available aliphatic amines and the feedstock gas carbon monoxide to form synthetically versatile value-added amide products. The operationally straightforward palladium-catalyzed process exploits a distinct reaction pathway, wherein a sterically hindered carboxylate ligand orchestrates an am
  
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• [Report] The sacral autonomic outflow is sympathetic

  17-11-2016 21:37
  A kinship between cranial and pelvic visceral nerves of vertebrates has been accepted for a century. Accordingly, sacral preganglionic neurons are considered parasympathetic, as are their targets in the pelvic ganglia that prominently control rectal, bladder, and genital functions. Here, we uncover 15 phenotypic and ontogenetic features that distinguish pre- and postganglionic neurons of the cranial parasympathetic outflow from those of the thoracolumbar sympathetic outflow in mice. By every sin
  
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• [Report] The formation of peak rings in large impact craters

  17-11-2016 21:37
  Large impacts provide a mechanism for resurfacing planets through mixing near-surface rocks with deeper material. Central peaks are formed from the dynamic uplift of rocks during crater formation. As crater size increases, central peaks transition to peak rings. Without samples, debate surrounds the mechanics of peak-ring formation and their depth of origin. Chicxulub is the only known impact structure on Earth with an unequivocal peak ring, but it is buried and only accessible through drilling.
  
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• [Report] The DNA methyltransferase DNMT3C protects male germ cells from transposon activity

  17-11-2016 21:37
  DNA methylation is prevalent in mammalian genomes and plays a central role in the epigenetic control of development. The mammalian DNA methylation machinery is thought to be composed of three DNA methyltransferase enzymes (DNMT1, DNMT3A, and DNMT3B) and one cofactor (DNMT3L). Here, we describe the discovery of Dnmt3C, a de novo DNA methyltransferase gene that evolved via a duplication of Dnmt3B in rodent genomes and was previously annotated as a pseudogene. We show that DNMT3C is the enzyme resp
  
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• [Report] Site-specific phosphorylation of tau inhibits amyloid-β toxicity in Alzheimer’s mice

  17-11-2016 21:37
  Amyloid-β (Aβ) toxicity in Alzheimer’s disease (AD) is considered to be mediated by phosphorylated tau protein. In contrast, we found that, at least in early disease, site-specific phosphorylation of tau inhibited Aβ toxicity. This specific tau phosphorylation was mediated by the neuronal p38 mitogen-activated protein kinase p38γ and interfered with postsynaptic excitotoxic signaling complexes engaged by Aβ. Accordingly, depletion of p38γ exacerbated neuronal circuit aberrations, cogniti
  
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• [Report] Single-particle mapping of nonequilibrium nanocrystal transformations

  17-11-2016 21:37
  Chemists have developed mechanistic insight into numerous chemical reactions by thoroughly characterizing nonequilibrium species. Although methods to probe these processes are well established for molecules, analogous techniques for understanding intermediate structures in nanomaterials have been lacking. We monitor the shape evolution of individual anisotropic gold nanostructures as they are oxidatively etched in a graphene liquid cell with a controlled redox environment. Short-lived, nonequili
  
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• [Report] Phytochromes function as thermosensors in Arabidopsis

  17-11-2016 21:37
  Plants are responsive to temperature, and some species can distinguish differences of 1°C. In Arabidopsis, warmer temperature accelerates flowering and increases elongation growth (thermomorphogenesis). However, the mechanisms of temperature perception are largely unknown. We describe a major thermosensory role for the phytochromes (red light receptors) during the night. Phytochrome null plants display a constitutive warm-temperature response, and consistent with this, we show in this backgroun
  
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• [Report] Phytochrome B integrates light and temperature signals in Arabidopsis

  17-11-2016 21:37
  Ambient temperature regulates many aspects of plant growth and development, but its sensors are unknown. Here, we demonstrate that the phytochrome B (phyB) photoreceptor participates in temperature perception through its temperature-dependent reversion from the active Pfr state to the inactive Pr state. Increased rates of thermal reversion upon exposing Arabidopsis seedlings to warm environments reduce both the abundance of the biologically active Pfr-Pfr dimer pool of phyB and the size of the a
  
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• [Report] Perovskite-perovskite tandem photovoltaics with optimized band gaps

  17-11-2016 21:37
  We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2–electron volt band-gap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that can deliver 14.8% efficiency. By combining this material with a wider–band gap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tande
  
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• [Report] Coseismic rupturing stopped by Aso volcano during the 2016 Mw 7.1 Kumamoto earthquake, Japan

  17-11-2016 21:37
  Field investigations and seismic data show that the 16 April 2016 moment magnitude (Mw) 7.1 Kumamoto earthquake produced a ~40-kilometer-long surface rupture zone along the northeast-southwest–striking Hinagu-Futagawa strike-slip fault zone and newly identified faults on the western side of Aso caldera, Kyushu Island, Japan. The coseismic surface ruptures cut Aso caldera, including two volcanic cones inside it, but terminate therein. The data show that northeastward propagation of coseismic ru
  
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• [Report] Command of active matter by topological defects and patterns

  17-11-2016 21:37
  Self-propelled bacteria are marvels of nature with a potential to power dynamic materials and microsystems of the future. The challenge lies in commanding their chaotic behavior. By dispersing swimming Bacillus subtilis in a liquid crystalline environment with spatially varying orientation of the anisotropy axis, we demonstrate control over the distribution of bacterial concentration, as well as the geometry and polarity of their trajectories. Bacteria recognize subtle differences in liquid crys
  
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• [Report] Characterization of a dynamic metabolon producing the defense compound dhurrin in sorghum

  17-11-2016 21:37
  Metabolic highways may be orchestrated by the assembly of sequential enzymes into protein complexes, or metabolons, to facilitate efficient channeling of intermediates and to prevent undesired metabolic cross-talk while maintaining metabolic flexibility. Here we report the isolation of the dynamic metabolon that catalyzes the formation of the cyanogenic glucoside dhurrin, a defense compound produced in sorghum plants. The metabolon was reconstituted in liposomes, which demonstrated the importanc
  
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• [Report] Asymmetric synthesis of batrachotoxin: Enantiomeric toxins show functional divergence against NaV

  17-11-2016 21:37
  The steroidal neurotoxin (−)-batrachotoxin functions as a potent agonist of voltage-gated sodium ion channels (NaVs). Here we report concise asymmetric syntheses of the natural (−) and non-natural (+) antipodes of batrachotoxin, as well both enantiomers of a C-20 benzoate–modified derivative. Electrophysiological characterization of these molecules against NaV subtypes establishes the non-natural toxin enantiomer as a reversible antagonist of channel function, markedly different in activit
  
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• [Report] A synthetic pathway for the fixation of carbon dioxide in vitro

  17-11-2016 21:37
  Carbon dioxide (CO2) is an important carbon feedstock for a future green economy. This requires the development of efficient strategies for its conversion into multicarbon compounds. We describe a synthetic cycle for the continuous fixation of CO2 in vitro. The crotonyl–coenzyme A (CoA)/ethylmalonyl-CoA/hydroxybutyryl-CoA (CETCH) cycle is a reaction network of 17 enzymes that converts CO2 into organic molecules at a rate of 5 nanomoles of CO2 per minute per milligram of protein. The CETCH cycl
  
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• [Policy Forum] Toward a national, sustained U.S. ecosystem assessment

  17-11-2016 21:37
  The massive investment of resources devoted to monitoring and assessment of economic and societal indicators in the United States is neither matched by nor linked to efforts to monitor and assess the ecosystem services and biodiversity that support economic and social well-being. Although national-scale assessments of biodiversity (1) and ecosystem indicators (2) have been undertaken, nearly a decade has elapsed since the last systematic assessment (2). A 2011 White House report called for a nat
  
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