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Muons’ big moment could fuel new physics

Nature - Tue, 04/11/2017 - 00:00

Muons’ big moment could fuel new physics

Nature 544, 7649 (2017). http://www.nature.com/doifinder/10.1038/544145a

Author: Elizabeth Gibney

Fermilab experiment to measure muon magnetic moment more precisely might reveal unknown virtual particles.

Categories: Literature

Make perovskite solar cells stable

Nature - Tue, 04/11/2017 - 00:00

Make perovskite solar cells stable

Nature 544, 7649 (2017). doi:10.1038/544155a

Authors: Yang Yang & Jingbi You

Stop these promising photovoltaics from degrading, urge Yang Yang and Jingbi You.

Categories: Literature

Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation

Nature - Mon, 04/10/2017 - 00:00

Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation

Nature 544, 7651 (2017). doi:10.1038/nature22032

Authors: Suihe Jiang, Hui Wang, Yuan Wu, Xiongjun Liu, Honghong Chen, Mengji Yao, Baptiste Gault, Dirk Ponge, Dierk Raabe, Akihiko Hirata, Mingwei Chen, Yandong Wang & Zhaoping Lu

Next-generation high-performance structural materials are required for lightweight design strategies and advanced energy applications. Maraging steels, combining a martensite matrix with nanoprecipitates, are a class of high-strength materials with the potential for matching these demands. Their outstanding strength originates from semi-coherent precipitates, which unavoidably exhibit a heterogeneous distribution that creates large coherency strains, which in turn may promote crack initiation under load. Here we report a counterintuitive strategy for the design of ultrastrong steel alloys by high-density nanoprecipitation with minimal lattice misfit. We found that these highly dispersed, fully coherent precipitates (that is, the crystal lattice of the precipitates is almost the same as that of the surrounding matrix), showing very low lattice misfit with the matrix and high anti-phase boundary energy, strengthen alloys without sacrificing ductility. Such low lattice misfit (0.03 ± 0.04 per cent) decreases the nucleation barrier for precipitation, thus enabling and stabilizing nanoprecipitates with an extremely high number density (more than 1024 per cubic metre) and small size (about 2.7 ± 0.2 nanometres). The minimized elastic misfit strain around the particles does not contribute much to the dislocation interaction, which is typically needed for strength increase. Instead, our strengthening mechanism exploits the chemical ordering effect that creates backstresses (the forces opposing deformation) when precipitates are cut by dislocations. We create a class of steels, strengthened by Ni(Al,Fe) precipitates, with a strength of up to 2.2 gigapascals and good ductility (about 8.2 per cent). The chemical composition of the precipitates enables a substantial reduction in cost compared to conventional maraging steels owing to the replacement of the essential but high-cost alloying elements cobalt and titanium with inexpensive and lightweight aluminium. Strengthening of this class of steel alloy is based on minimal lattice misfit to achieve maximal precipitate dispersion and high cutting stress (the stress required for dislocations to cut through coherent precipitates and thus produce plastic deformation), and we envisage that this lattice misfit design concept may be applied to many other metallic alloys.

Categories: Literature

Arctic Ocean Undergoing “Atlantification,” Scientists Say

Yale Environment 360 - Fri, 04/07/2017 - 10:42

Parts of the Arctic Ocean are quickly becoming more like the Atlantic, researchers warned this week in the journal Science. As warm waters creep north, the ocean is beginning to mix vertically more than it used to, melting sea ice from below. The scientists referred to the process as the “Atlantification” of the Arctic.

Read more on E360 →

Categories: Environmental News

Natural-history collections face fight for survival

Nature - Fri, 04/07/2017 - 00:00

Natural-history collections face fight for survival

Nature 544, 7649 (2017). doi:10.1038/544137b

Regional hubs offer lifeline to museums’ precious plant and animal specimens.

Categories: Literature

Mobile-phone signals bolster street-level rain forecasts

Nature - Fri, 04/07/2017 - 00:00

Mobile-phone signals bolster street-level rain forecasts

Nature 544, 7649 (2017). http://www.nature.com/doifinder/10.1038/nature.2017.21799

Author: Jeff Tollefson

Real-time analysis of wireless communications data could improve weather forecasts around the world.

Categories: Literature

The Vanishing Nile: A Great River Faces a Multitude of Threats

Yale Environment 360 - Thu, 04/06/2017 - 06:41

The Nile River is under assault on two fronts – a massive dam under construction upstream in Ethiopia and rising sea levels leading to saltwater intrusion downstream. These dual threats now jeopardize the future of a river that is the lifeblood for millions.

Read more on E360 →

Categories: Environmental News

With Climate Change Deniers in Charge, Time for Scientists to Step Up

Yale Environment 360 - Thu, 04/06/2017 - 04:00

In a Yale e360 interview, researcher Kevin Trenberth talks about why climate scientists need to speak out in the face of the Trump administration’s denial of the facts about climate change.

Read more on E360 →

Categories: Environmental News

U.S. EPA Proposes Cutting Programs That Reduce Lead Exposure

Yale Environment 360 - Wed, 04/05/2017 - 10:05

The Environmental Protection Agency is proposing to cut $16.6 million and more than 70 employees from federal programs aimed at reducing lead risks, including eliminating two programs that focus on limiting children’s exposure to lead-based paint, The Washington Post reported.

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Categories: Environmental News

Structural biology: A receptor that might block itself

Nature - Wed, 04/05/2017 - 00:00

Structural biology: A receptor that might block itself

Nature 544, 7650 (2017). doi:10.1038/nature21907

Authors: Christopher G. Tate

The structure of the angiotensin II type 2 receptor reveals a potential mode of self-blocking action. This might explain its lack of signalling, and opens up avenues of investigation into its function and role in disease. See Article p.327

Categories: Literature

Structural basis for selectivity and diversity in angiotensin II receptors

Nature - Wed, 04/05/2017 - 00:00

Structural basis for selectivity and diversity in angiotensin II receptors

Nature 544, 7650 (2017). doi:10.1038/nature22035

Authors: Haitao Zhang, Gye Won Han, Alexander Batyuk, Andrii Ishchenko, Kate L. White, Nilkanth Patel, Anastasiia Sadybekov, Beata Zamlynny, Michael T. Rudd, Kaspar Hollenstein, Alexandra Tolstikova, Thomas A. White, Mark S. Hunter, Uwe Weierstall, Wei Liu, Kerim Babaoglu, Eric L. Moore, Ryan D. Katz, Jennifer M. Shipman, Margarita Garcia-Calvo, Sujata Sharma, Payal Sheth, Stephen M. Soisson, Raymond C. Stevens, Vsevolod Katritch & Vadim Cherezov

The angiotensin II receptors AT1R and AT2R serve as key components of the renin–angiotensin–aldosterone system. AT1R has a central role in the regulation of blood pressure, but the function of AT2R is unclear and it has a

Categories: Literature

Marine conservation: The race to fish slows down

Nature - Wed, 04/05/2017 - 00:00

Marine conservation: The race to fish slows down

Nature 544, 7649 (2017). doi:10.1038/nature21906

Authors: Andrew A. Rosenberg

A fishery can allow participants to fish as hard as they can until its quota is reached, or allocate quota shares that can be caught at any time. A comparison of the systems in action reveals that shares slow the race to fish. See Letter p.223

Categories: Literature

Materials science: Screen printing of 2D semiconductors

Nature - Wed, 04/05/2017 - 00:00

Materials science: Screen printing of 2D semiconductors

Nature 544, 7649 (2017). doi:10.1038/nature21908

Authors: Young Duck Kim & James Hone

Atomically thin semiconductors have been made by transferring the oxide 'skin' of a liquid metal to substrates. This opens the way to the low-cost mass production of 2D semiconductors at the sizes needed for electronics applications.

Categories: Literature

Biocontrol: Crown-of-thorns no more

Nature - Wed, 04/05/2017 - 00:00

Biocontrol: Crown-of-thorns no more

Nature 544, 7649 (2017). doi:10.1038/nature21905

Authors: Mónica Medina

The starfish Acanthaster planci destroys coral reefs. Whole- genome sequences provide clues to the proteins that mediate A. planci outbreaks — information that might be used to help protect coral. See Letter p.231

Categories: Literature

Mono-unsaturated fatty acids link H3K4me3 modifiers to C. elegans lifespan

Nature - Wed, 04/05/2017 - 00:00

Mono-unsaturated fatty acids link H3K4me3 modifiers to C. elegans lifespan

Nature 544, 7649 (2017). doi:10.1038/nature21686

Authors: Shuo Han, Elizabeth A. Schroeder, Carlos G. Silva-García, Katja Hebestreit, William B. Mair & Anne Brunet

Chromatin and metabolic states both influence lifespan, but how they interact in lifespan regulation is largely unknown. The COMPASS chromatin complex, which trimethylates lysine 4 on histone H3 (H3K4me3), regulates lifespan in Caenorhabditis elegans. However, the mechanism by which H3K4me3 modifiers affect longevity, and

Categories: Literature

Catch shares slow the race to fish

Nature - Wed, 04/05/2017 - 00:00

Catch shares slow the race to fish

Nature 544, 7649 (2017). doi:10.1038/nature21728

Authors: Anna M. Birkenbach, David J. Kaczan & Martin D. Smith

In fisheries, the tragedy of the commons manifests as a competitive race to fish that compresses fishing seasons, resulting in ecological damage, economic waste, and occupational hazards. Catch shares are hypothesized to halt the race by securing each individual’s right to a portion of the total catch, but there is evidence for this from selected examples only. Here we systematically analyse natural experiments to test whether catch shares reduce racing in 39 US fisheries. We compare each fishery treated with catch shares to an individually matched control before and after the policy change. We estimate an average policy treatment effect in a pooled model and in a meta-analysis that combines separate estimates for each treatment–control pair. Consistent with the theory that market-based management ends the race to fish, we find strong evidence that catch shares extend fishing seasons. This evidence informs the current debate over expanding the use of market-based regulation to other fisheries.

Categories: Literature

The crown-of-thorns starfish genome as a guide for biocontrol of this coral reef pest

Nature - Wed, 04/05/2017 - 00:00

The crown-of-thorns starfish genome as a guide for biocontrol of this coral reef pest

Nature 544, 7649 (2017). doi:10.1038/nature22033

Authors: Michael R. Hall, Kevin M. Kocot, Kenneth W. Baughman, Selene L. Fernandez-Valverde, Marie E. A. Gauthier, William L. Hatleberg, Arunkumar Krishnan, Carmel McDougall, Cherie A. Motti, Eiichi Shoguchi, Tianfang Wang, Xueyan Xiang, Min Zhao, Utpal Bose, Chuya Shinzato, Kanako Hisata, Manabu Fujie, Miyuki Kanda, Scott F. Cummins, Noriyuki Satoh, Sandie M. Degnan & Bernard M. Degnan

The crown-of-thorns starfish (COTS, the Acanthaster planci species group) is a highly fecund predator of reef-building corals throughout the Indo-Pacific region. COTS population outbreaks cause substantial loss of coral cover, diminishing the integrity and resilience of reef ecosystems. Here we sequenced genomes of COTS from the Great Barrier Reef, Australia and Okinawa, Japan to identify gene products that underlie species-specific communication and could potentially be used in biocontrol strategies. We focused on water-borne chemical plumes released from aggregating COTS, which make the normally sedentary starfish become highly active. Peptide sequences detected in these plumes by mass spectrometry are encoded in the COTS genome and expressed in external tissues. The exoproteome released by aggregating COTS consists largely of signalling factors and hydrolytic enzymes, and includes an expanded and rapidly evolving set of starfish-specific ependymin-related proteins. These secreted proteins may be detected by members of a large family of olfactory-receptor-like G-protein-coupled receptors that are expressed externally, sometimes in a sex-specific manner. This study provides insights into COTS-specific communication that may guide the generation of peptide mimetics for use on reefs with COTS outbreaks.

Categories: Literature

Re-evaluation of learned information in Drosophila

Nature - Wed, 04/05/2017 - 00:00

Re-evaluation of learned information in Drosophila

Nature 544, 7649 (2017). doi:10.1038/nature21716

Authors: Johannes Felsenberg, Oliver Barnstedt, Paola Cognigni, Suewei Lin & Scott Waddell

Animals constantly assess the reliability of learned information to optimize their behaviour. On retrieval, consolidated long-term memory can be neutralized by extinction if the learned prediction was inaccurate. Alternatively, retrieved memory can be maintained, following a period of reconsolidation during which it is labile. Although extinction and reconsolidation provide opportunities to alleviate problematic human memories, we lack a detailed mechanistic understanding of memory updating. Here we identify neural operations underpinning the re-evaluation of memory in Drosophila. Reactivation of reward-reinforced olfactory memory can lead to either extinction or reconsolidation, depending on prediction accuracy. Each process recruits activity in specific parts of the mushroom body output network and distinct subsets of reinforcing dopaminergic neurons. Memory extinction requires output neurons with dendrites in the α and α′ lobes of the mushroom body, which drive negatively reinforcing dopaminergic neurons that innervate neighbouring zones. The aversive valence of these new extinction memories neutralizes previously learned odour preference. Memory reconsolidation requires the γ2α′1 mushroom body output neurons. This pathway recruits negatively reinforcing dopaminergic neurons innervating the same compartment and re-engages positively reinforcing dopaminergic neurons to reconsolidate the original reward memory. These data establish that recurrent and hierarchical connectivity between mushroom body output neurons and dopaminergic neurons enables memory re-evaluation driven by reward-prediction error.

Categories: Literature

Myt1l safeguards neuronal identity by actively repressing many non-neuronal fates

Nature - Wed, 04/05/2017 - 00:00

Myt1l safeguards neuronal identity by actively repressing many non-neuronal fates

Nature 544, 7649 (2017). doi:10.1038/nature21722

Authors: Moritz Mall, Michael S. Kareta, Soham Chanda, Henrik Ahlenius, Nicholas Perotti, Bo Zhou, Sarah D. Grieder, Xuecai Ge, Sienna Drake, Cheen Euong Ang, Brandon M. Walker, Thomas Vierbuchen, Daniel R. Fuentes, Philip Brennecke, Kazuhiro R. Nitta, Arttu Jolma, Lars M. Steinmetz, Jussi Taipale, Thomas C. Südhof & Marius Wernig

Normal differentiation and induced reprogramming require the activation of target cell programs and silencing of donor cell programs. In reprogramming, the same factors are often used to reprogram many different donor cell types. As most developmental repressors, such as RE1-silencing transcription factor (REST) and Groucho (also known as TLE), are considered lineage-specific repressors, it remains unclear how identical combinations of transcription factors can silence so many different donor programs. Distinct lineage repressors would have to be induced in different donor cell types. Here, by studying the reprogramming of mouse fibroblasts to neurons, we found that the pan neuron-specific transcription factor Myt1-like (Myt1l) exerts its pro-neuronal function by direct repression of many different somatic lineage programs except the neuronal program. The repressive function of Myt1l is mediated via recruitment of a complex containing Sin3b by binding to a previously uncharacterized N-terminal domain. In agreement with its repressive function, the genomic binding sites of Myt1l are similar in neurons and fibroblasts and are preferentially in an open chromatin configuration. The Notch signalling pathway is repressed by Myt1l through silencing of several members, including Hes1. Acute knockdown of Myt1l in the developing mouse brain mimicked a Notch gain-of-function phenotype, suggesting that Myt1l allows newborn neurons to escape Notch activation during normal development. Depletion of Myt1l in primary postmitotic neurons de-repressed non-neuronal programs and impaired neuronal gene expression and function, indicating that many somatic lineage programs are actively and persistently repressed by Myt1l to maintain neuronal identity. It is now tempting to speculate that similar ‘many-but-one’ lineage repressors exist for other cell fates; such repressors, in combination with lineage-specific activators, would be prime candidates for use in reprogramming additional cell types.

Categories: Literature

How to judge a book by its network

Nature - Wed, 04/05/2017 - 00:00

How to judge a book by its network

Nature 544, 7648 (2017). doi:10.1038/544005b

A breakdown of purchasing habits shows where science books fall on the political spectrum.

Categories: Literature

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