[Working Life] Learning from rejections Science (IF34.661) 2017-03-24 Andy Tay
Author: Andy Tay
[New Products] New Products Science (IF34.661) 2017-03-24
A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.
[Report] Stem cell divisions, somatic mutations, cancer etiology, and cancer prevention Science (IF34.661) 2017-03-24 Cristian Tomasetti, Lu Li, Bert Vogelstein
Cancers are caused by mutations that may be inherited, induced by environmental factors, or result from DNA replication errors (R). We studied the relationship between the number of normal stem cell divisions and the risk of 17 cancer types in 69 countries throughout the world. The data revealed a strong correlation (median = 0.80) between cancer incidence and normal stem cell divisions in all countries, regardless of their environment. The major role of R mutations in cancer etiology was supported by an independent approach, based solely on cancer genome sequencing and epidemiological data, which suggested that R mutations are responsible for two-thirds of the mutations in human cancers. All of these results are consistent with epidemiological estimates of the fraction of cancers that can be prevented by changes in the environment. Moreover, they accentuate the importance of early detection and intervention to reduce deaths from the many cancers arising from unavoidable R mutations.
[Report] PI3K pathway regulates ER-dependent transcription in breast cancer through the epigenetic regulator KMT2D Science (IF34.661) 2017-03-24 Eneda Toska, Hatice U. Osmanbeyoglu, Pau Castel, Carmen Chan, Ronald C. Hendrickson, Moshe Elkabets, Maura N. Dickler, Maurizio Scaltriti, Christina S. Leslie, Scott A. Armstrong, José Baselga
Activating mutations in PIK3CA, the gene encoding phosphoinositide-(3)-kinase α (PI3Kα), are frequently found in estrogen receptor (ER)–positive breast cancer. PI3Kα inhibitors, now in late-stage clinical development, elicit a robust compensatory increase in ER-dependent transcription that limits therapeutic efficacy. We investigated the chromatin-based mechanisms leading to the activation of ER upon PI3Kα inhibition. We found that PI3Kα inhibition mediates an open chromatin state at the ER target loci in breast cancer models and clinical samples. KMT2D, a histone H3 lysine 4 methyltransferase, is required for FOXA1, PBX1, and ER recruitment and activation. AKT binds and phosphorylates KMT2D, attenuating methyltransferase activity and ER function, whereas PI3Kα inhibition enhances KMT2D activity. These findings uncover a mechanism that controls the activation of ER by the posttranslational modification of epigenetic regulators, providing a rationale for epigenetic therapy in ER-positive breast cancer.
[Report] Notch-Jagged complex structure implicates a catch bond in tuning ligand sensitivity Science (IF34.661) 2017-03-24 Vincent C. Luca, Byoung Choul Kim, Chenghao Ge, Shinako Kakuda, Di Wu, Mehdi Roein-Peikar, Robert S. Haltiwanger, Cheng Zhu, Taekjip Ha, K. Christopher Garcia
Notch receptor activation initiates cell fate decisions and is distinctive in its reliance on mechanical force and protein glycosylation. The 2.5-angstrom-resolution crystal structure of the extracellular interacting region of Notch1 complexed with an engineered, high-affinity variant of Jagged1 (Jag1) reveals a binding interface that extends ~120 angstroms along five consecutive domains of each protein. O-Linked fucose modifications on Notch1 epidermal growth factor–like (EGF) domains 8 and 12 engage the EGF3 and C2 domains of Jag1, respectively, and different Notch1 domains are favored in binding to Jag1 than those that bind to the Delta-like 4 ligand. Jag1 undergoes conformational changes upon Notch binding, exhibiting catch bond behavior that prolongs interactions in the range of forces required for Notch activation. This mechanism enables cellular forces to regulate binding, discriminate among Notch ligands, and potentiate Notch signaling.
[Report] A macrophage relay for long-distance signaling during postembryonic tissue remodeling Science (IF34.661) 2017-03-24 Dae Seok Eom, David M. Parichy
Macrophages have diverse functions in immunity as well as in development and homeostasis. We identified a function for these cells in long-distance communication during postembryonic tissue remodeling. Ablation of macrophages in zebrafish prevented melanophores from coalescing into adult pigment stripes. Melanophore organization depends on signals provided by cells of the yellow xanthophore lineage via airinemes, long filamentous projections with vesicles at their tips. We show that airineme extension from originating cells, as well as vesicle deposition on target cells, depend on interactions with macrophages. These findings identify a role for macrophages in relaying long-range signals between nonimmune cells. This signaling modality may function in the remodeling and homeostasis of other tissues during normal development and disease.
[Report] A conserved NAD+ binding pocket that regulates protein-protein interactions during aging Science (IF34.661) 2017-03-24 Jun Li, Michael S. Bonkowski, Sébastien Moniot, Dapeng Zhang, Basil P. Hubbard, Alvin J. Y. Ling, Luis A. Rajman, Bo Qin, Zhenkun Lou, Vera Gorbunova, L. Aravind, Clemens Steegborn, David A. Sinclair
DNA repair is essential for life, yet its efficiency declines with age for reasons that are unclear. Numerous proteins possess Nudix homology domains (NHDs) that have no known function. We show that NHDs are NAD+ (oxidized form of nicotinamide adenine dinucleotide) binding domains that regulate protein-protein interactions. The binding of NAD+ to the NHD domain of DBC1 (deleted in breast cancer 1) prevents it from inhibiting PARP1 [poly(adenosine diphosphate–ribose) polymerase], a critical DNA repair protein. As mice age and NAD+ concentrations decline, DBC1 is increasingly bound to PARP1, causing DNA damage to accumulate, a process rapidly reversed by restoring the abundance of NAD+. Thus, NAD+ directly regulates protein-protein interactions, the modulation of which may protect against cancer, radiation, and aging.
[Report] Lysosomal cholesterol activates mTORC1 via an SLC38A9–Niemann-Pick C1 signaling complex Science (IF34.661) 2017-03-24 Brian M. Castellano, Ashley M. Thelen, Ofer Moldavski, McKenna Feltes, Reini E. N. van der Welle, Laurel Mydock-McGrane, Xuntian Jiang, Robert J van Eijkeren, Oliver B. Davis, Sharon M. Louie, Rushika M. Perera, Douglas F. Covey, Daniel K. Nomura, Daniel S. Ory, Roberto Zoncu
The mechanistic target of rapamycin complex 1 (mTORC1) protein kinase is a master growth regulator that becomes activated at the lysosome in response to nutrient cues. Here, we identify cholesterol, an essential building block for cellular growth, as a nutrient input that drives mTORC1 recruitment and activation at the lysosomal surface. The lysosomal transmembrane protein, SLC38A9, is required for mTORC1 activation by cholesterol through conserved cholesterol-responsive motifs. Moreover, SLC38A9 enables mTORC1 activation by cholesterol independently from its arginine-sensing function. Conversely, the Niemann-Pick C1 (NPC1) protein, which regulates cholesterol export from the lysosome, binds to SLC38A9 and inhibits mTORC1 signaling through its sterol transport function. Thus, lysosomal cholesterol drives mTORC1 activation and growth signaling through the SLC38A9-NPC1 complex.
[Report] Dengue diversity across spatial and temporal scales: Local structure and the effect of host population size Science (IF34.661) 2017-03-24 Henrik Salje, Justin Lessler, Irina Maljkovic Berry, Melanie C. Melendrez, Timothy Endy, Siripen Kalayanarooj, Atchareeya A-Nuegoonpipat, Sumalee Chanama, Somchai Sangkijporn, Chonticha Klungthong, Butsaya Thaisomboonsuk, Ananda Nisalak, Robert V. Gibbons, Sopon Iamsirithaworn, Louis R. Macareo, In-Kyu Yoon, Areerat Sangarsang, Richard G. Jarman, Derek A. T. Cummings
A fundamental mystery for dengue and other infectious pathogens is how observed patterns of cases relate to actual chains of individual transmission events. These pathways are intimately tied to the mechanisms by which strains interact and compete across spatial scales. Phylogeographic methods have been used to characterize pathogen dispersal at global and regional scales but have yielded few insights into the local spatiotemporal structure of endemic transmission. Using geolocated genotype (800 cases) and serotype (17,291 cases) data, we show that in Bangkok, Thailand, 60% of dengue cases living <200 meters apart come from the same transmission chain, as opposed to 3% of cases separated by 1 to 5 kilometers. At distances <200 meters from a case (encompassing an average of 1300 people in Bangkok), the effective number of chains is 1.7. This number rises by a factor of 7 for each 10-fold increase in the population of the “enclosed” region. This trend is observed regardless of whether population density or area increases, though increases in density over 7000 people per square kilometer do not lead to additional chains. Within Thailand these chains quickly mix, and by the next dengue season viral lineages are no longer highly spatially structured within the country. In contrast, viral flow to neighboring countries is limited. These findings are consistent with local, density-dependent transmission and implicate densely populated communities as key sources of viral diversity, with home location the focal point of transmission. These findings have important implications for targeted vector control and active surveillance.
[Report] How “you” makes meaning Science (IF34.661) 2017-03-24 Ariana Orvell, Ethan Kross, Susan A. Gelman
“You” is one of the most common words in the English language. Although it typically refers to the person addressed (“How are you?”), “you” is also used to make timeless statements about people in general (“You win some, you lose some.”). Here, we demonstrate that this ubiquitous but understudied linguistic device, known as “generic-you,” has important implications for how people derive meaning from experience. Across six experiments, we found that generic-you is used to express norms in both ordinary and emotional contexts and that producing generic-you when reflecting on negative experiences allows people to “normalize” their experience by extending it beyond the self. In this way, a simple linguistic device serves a powerful meaning-making function.
[Report] Active sites for CO2 hydrogenation to methanol on Cu/ZnO catalysts Science (IF34.661) 2017-03-24 Shyam Kattel, Pedro J. Ramírez, Jingguang G. Chen, José A. Rodriguez, Ping Liu
The active sites over commercial copper/zinc oxide/aluminum oxide (Cu/ZnO/Al2O3) catalysts for carbon dioxide (CO2) hydrogenation to methanol, the Zn-Cu bimetallic sites or ZnO-Cu interfacial sites, have recently been the subject of intense debate. We report a direct comparison between the activity of ZnCu and ZnO/Cu model catalysts for methanol synthesis. By combining x-ray photoemission spectroscopy, density functional theory, and kinetic Monte Carlo simulations, we can identify and characterize the reactivity of each catalyst. Both experimental and theoretical results agree that ZnCu undergoes surface oxidation under the reaction conditions so that surface Zn transforms into ZnO and allows ZnCu to reach the activity of ZnO/Cu with the same Zn coverage. Our results highlight a synergy of Cu and ZnO at the interface that facilitates methanol synthesis via formate intermediates.
[Report] Grain boundary stability governs hardening and softening in extremely fine nanograined metals Science (IF34.661) 2017-03-24 J. Hu, Y. N. Shi, X. Sauvage, G. Sha, K. Lu
Conventional metals become harder with decreasing grain sizes, following the classical Hall-Petch relationship. However, this relationship fails and softening occurs at some grain sizes in the nanometer regime for some alloys. In this study, we discovered that plastic deformation mechanism of extremely fine nanograined metals and their hardness are adjustable through tailoring grain boundary (GB) stability. The electrodeposited nanograined nickel-molybdenum (Ni–Mo) samples become softened for grain sizes below 10 nanometers because of GB-mediated processes. With GB stabilization through relaxation and Mo segregation, ultrahigh hardness is achieved in the nanograined samples with a plastic deformation mechanism dominated by generation of extended partial dislocations. Grain boundary stability provides an alternative dimension, in addition to grain size, for producing novel nanograined metals with extraordinary properties.
[Report] Extremely efficient internal exciton dissociation through edge states in layered 2D perovskites Science (IF34.661) 2017-03-24 J.-C. Blancon, H. Tsai, W. Nie, C. C. Stoumpos, L. Pedesseau, C. Katan, M. Kepenekian, C. M. M. Soe, K. Appavoo, M. Y. Sfeir, S. Tretiak, P. M. Ajayan, M. G. Kanatzidis, J. Even, J. J. Crochet, A. D. Mohite
Understanding and controlling charge and energy flow in state-of-the-art semiconductor quantum wells has enabled high-efficiency optoelectronic devices. Two-dimensional (2D) Ruddlesden-Popper perovskites are solution-processed quantum wells wherein the band gap can be tuned by varying the perovskite-layer thickness, which modulates the effective electron-hole confinement. We report that, counterintuitive to classical quantum-confined systems where photogenerated electrons and holes are strongly bound by Coulomb interactions or excitons, the photophysics of thin films made of Ruddlesden-Popper perovskites with a thickness exceeding two perovskite-crystal units (>1.3 nanometers) is dominated by lower-energy states associated with the local intrinsic electronic structure of the edges of the perovskite layers. These states provide a direct pathway for dissociating excitons into longer-lived free carriers that substantially improve the performance of optoelectronic devices.
[Report] [C ii] 158-μm emission from the host galaxies of damped Lyman-alpha systems Science (IF34.661) 2017-03-24 Marcel Neeleman, Nissim Kanekar, J. Xavier Prochaska, Marc Rafelski, Chris L. Carilli, Arthur M. Wolfe
Gas surrounding high-redshift galaxies has been studied through observations of absorption line systems toward background quasars for decades. However, it has proven difficult to identify and characterize the galaxies associated with these absorbers due to the intrinsic faintness of the galaxies compared with the quasars at optical wavelengths. Using the Atacama Large Millimeter/Submillimeter Array, we report on detections of [C ii] 158-μm line and dust-continuum emission from two galaxies associated with two such absorbers at a redshift of z ~ 4. Our results indicate that the hosts of these high-metallicity absorbers have physical properties similar to massive star-forming galaxies and are embedded in enriched neutral hydrogen gas reservoirs that extend well beyond the star-forming interstellar medium of these galaxies.
[Editors' Choice] Dirac cones in a boron monolayer Science (IF34.661) 2017-03-24 Jelena Stajic
Author: Jelena Stajic
[Editors' Choice] Notch1 promotes cancer spread Science (IF34.661) 2017-03-24 Priscilla N. Kelly
Author: Priscilla N. Kelly
[Editors' Choice] Recovering galaxy images from noisy data Science (IF34.661) 2017-03-24 Keith T. Smith
Author: Keith T. Smith
[Editors' Choice] The evolution of edited RNA transcripts Science (IF34.661) 2017-03-24 Laura M. Zahn
Author: Laura M. Zahn
[Editors' Choice] Stronger pancreas through starvation Science (IF34.661) 2017-03-24 L. Bryan Ray
Author: L. Bryan Ray
[Editors' Choice] Turning toys into tools Science (IF34.661) 2017-03-24 Megan Eldred
Author: Megan Eldred
[Editors' Choice] A new angle on streams Science (IF34.661) 2017-03-24 H. Jesse Smith
Author: H. Jesse Smith
[This Week in Science] It's easier to see green Science (IF34.661) 2017-03-24 Shahid Naeem
Author: Shahid Naeem
[This Week in Science] Influenz-ing IFN responses in dendritic cells Science (IF34.661) 2017-03-24 Lindsey Pujanandez
Author: Lindsey Pujanandez
[This Week in Science] Fire management, made to measure Science (IF34.661) 2017-03-24 Julia Fahrenkamp-Uppenbrink
Author: Julia Fahrenkamp-Uppenbrink
[This Week in Science] Tugging on Notch receptor tunes signaling Science (IF34.661) 2017-03-24 L. Bryan Ray
Author: L. Bryan Ray
[This Week in Science] NAD+ binding modulates protein interactions Science (IF34.661) 2017-03-24 L. Bryan Ray
Author: L. Bryan Ray
[This Week in Science] Lysosomal cholesterol activates mTORC1 Science (IF34.661) 2017-03-24 L. Bryan Ray
Author: L. Bryan Ray
[This Week in Science] Chromatin state dictates drug response Science (IF34.661) 2017-03-24 Paula A. Kiberstis
Author: Paula A. Kiberstis
[This Week in Science] How perovskites have the edge Science (IF34.661) 2017-03-24 Phil Szuromi
Author: Phil Szuromi
[This Week in Science] Go with the changing flow Science (IF34.661) 2017-03-24 Marc S. Lavine
Author: Marc S. Lavine
[This Week in Science] Protein-folded DNA nanostructures Science (IF34.661) 2017-03-24 Phil Szuromi
Author: Phil Szuromi
[This Week in Science] Added complexity in an asymmetric receptor Science (IF34.661) 2017-03-24 Valda Vinson
Author: Valda Vinson
[This Week in Science] Dendrites are more active than expected Science (IF34.661) 2017-03-24 Peter Stern
Author: Peter Stern
[This Week in Science] Making magma chambers from mush Science (IF34.661) 2017-03-24 Brent Grocholski
Author: Brent Grocholski
[This Week in Science] Cancer and the unavoidable R factor Science (IF34.661) 2017-03-24 Paula A. Kiberstis
Author: Paula A. Kiberstis
[This Week in Science] Why pain and stress lead to depression Science (IF34.661) 2017-03-24 Leslie K. Ferrarelli
Author: Leslie K. Ferrarelli
[This Week in Science] Helping T cells feel at home in the liver Science (IF34.661) 2017-03-24 Angela Colmone
Author: Angela Colmone
[This Week in Science] Estimating transmission chains for dengue Science (IF34.661) 2017-03-24 Caroline Ash
Author: Caroline Ash
[This Week in Science] Using “you” to generalize from me to others Science (IF34.661) 2017-03-24 Gilbert Chin
Author: Gilbert Chin
[This Week in Science] Metal-oxide synergy Science (IF34.661) 2017-03-24 Phil Szuromi
Author: Phil Szuromi
[This Week in Science] Nanograined metals avoid going soft Science (IF34.661) 2017-03-24 Brent Grocholski
Author: Brent Grocholski
[This Week in Science] Cell projections set up pigment pattern Science (IF34.661) 2017-03-24 Beverly A. Purnell
Author: Beverly A. Purnell
[This Week in Science] Identifying the hosts of quasar absorbers Science (IF34.661) 2017-03-24 Keith T. Smith
Author: Keith T. Smith
[Letter] Specimen collection crucial to taxonomy Science (IF34.661) 2017-03-24 Eliécer E. Gutiérrez
Authors: Eliécer E. Gutiérrez, Ronald H. Pine
[Letter] Patent pools for CRISPR technology—Response Science (IF34.661) 2017-03-24 Jorge L. Contreras
Authors: Jorge L. Contreras, Jacob S. Sherkow
[Letter] Patent pools for CRISPR technology Science (IF34.661) 2017-03-24 Lawrence Horn
Author: Lawrence Horn
[Book Review] Rain check Science (IF34.661) 2017-03-24 Author: Sarah Dry
Make It Rain, Kristine Harper's detailed history of weather control in the United States, includes colorful details of cloud-seeding experiments, but the book is not so much about attempts to control the weather as it is about the political battles waged over the harnessing of the atmosphere: the control of weather control itself. Rather than revealing a history of what we might today call evidence-led policy, the book is a rogue's gallery of policy-led evidence, offering lessons about how science can be used as a tool of the state.
[Policy Forum] A roadmap for rapid decarbonization Science (IF34.661) 2017-03-24 Johan Rockström, Owen Gaffney, Joeri Rogelj, Malte Meinshausen, Nebojsa Nakicenovic, Hans Joachim Schellnhuber
Although the Paris Agreement's goals (1) are aligned with science (2) and can, in principle, be technically and economically achieved (3), alarming inconsistencies remain between science-based targets and national commitments. Despite progress during the 2016 Marrakech climate negotiations, long-term goals can be trumped by political short-termism. Following the Agreement, which became international law earlier than expected, several countries published mid-century decarbonization strategies, with more due soon. Model-based decarbonization assessments (4) and scenarios often struggle to capture transformative change and the dynamics associated with it: disruption, innovation, and nonlinear change in human behavior. For example, in just 2 years, China's coal use swung from 3.7% growth in 2013 to a decline of 3.7% in 2015 (5). To harness these dynamics and to calibrate for short-term realpolitik, we propose framing the decarbonization challenge in terms of a global decadal roadmap based on a simple heuristic—a “carbon law”—of halving gross anthropogenic carbon-dioxide (CO2) emissions every decade. Complemented by immediately instigated, scalable carbon removal and efforts to ramp down land-use CO2 emissions, this can lead to net-zero emissions around mid-century, a path necessary to limit warming to well below 2°C.
[Retrospective] Hans Rosling (1948–2017) Science (IF34.661) 2017-03-24 Bill Gates, Melinda Gates
Like a lot of Hans Rosling's admirers, we discovered his work via his famous 2006 TED talk, “The Best Stats You've Ever Seen.” It was a mind-blowing speech (with more than 11 million views to date) with innovative graphics, good jokes, and a profound message: The world is getting better, and even some of the poorest countries are making progress. Hans was a showman, but he didn't sacrifice an ounce of complexity. He was—and this is a term of honor in our house—a data nerd. We sang his praises to just about anyone who would listen.
[Perspective] Genes, environment, and “bad luck” Science (IF34.661) 2017-03-24 Martin A. Nowak, Bartlomiej Waclaw
It is a human trait to search for explanations for catastrophic events and rule out mere “chance” or “bad luck.” When it comes to human cancer, the issue of natural causes versus bad luck was raised by Tomasetti and Vogelstein about 2 years ago (1). Their study, which was widely misinterpreted as saying that most cancers are due neither to genetic inheritance nor environmental factors but simply bad luck, sparked controversy. To date, a few hundred papers have been written in response, including (2–6), with some [e.g., (2)] coming to opposite conclusions. What is this controversy about? Tomasetti and Vogelstein concluded that 65% of the differences in the risk of certain cancers is linked to stem cell divisions in the various cancerous tissues examined (1). On page 1330 of this issue, Tomasetti et al. (7) provide further evidence that this is not specific to the United States.
[Perspective] Using fire to promote biodiversity Science (IF34.661) 2017-03-24 L. T. Kelly, L. Brotons
Fire profoundly influences people, climate, and ecosystems (1). The impacts of this interaction are likely to grow, with climate models forecasting widespread increases in fire frequency and intensity because of rising global temperatures (2). However, the relationship between fire and biodiversity is complex (3, 4). Many plants and animals require fire for their survival, yet even in fire-prone ecosystems, some species and communities are highly sensitive to fire. Recent studies (2, 3, 5, 6) are helping to define fire regimes that support the conservation of species with different requirements in a rapidly changing world.
[Perspective] From chaos to order in active fluids Science (IF34.661) 2017-03-24 flock of birds that suddenly gives way to a directional motion. Arguably, our
There are few sights more spectacular than the swarming of a school of fish or a
[Perspective] Bringing proteins into the fold Science (IF34.661) 2017-03-24 building blocks to make custom self-assembled shapes. Because a single drop of
Molecular engineers have become increasingly adept at repurposing life's
[Perspective] Powering up perovskite photoresponse Science (IF34.661) 2017-03-24 Osman M. Bakr, Omar F. Mohammed
The most notable scientific milestone in photovoltaics in the past several years is the emergence of solar cells based on hybrid organic-inorganic perovskite materials. While conventional silicon and thin-film solar cells have seen steady improvements in their power-conversion efficiencies (PCEs) spanning several decades, hybrid perovskite solar cells have already reached a certified 22.1% PCE (1), matching conventional solar cell technologies in only a few years since their first device architecture was tested. Setting the stage for a disruptive technology in the field of photovoltaics is the seemingly winning combination of properties of hybrid perovskite materials: high absorption coefficient and a tunable energy band gap in wavelengths ideal for solar cells; long diffusion lengths and lifetimes for photogenerated charge carriers, which easily dissociate into efficiently collected electrons and holes; Earth-abundant elemental composition; and their compatibility with low-cost and low-temperature fabrication methods (2–5). On page 1288 of this issue, Blancon et al. (6) report on the observation of an enhanced photoresponse for layered perovskite materials. The results add, literally, a new dimension to the further development of high-performance perovskite solar cells.
[Perspective] Macrophage, a long-distance middleman Science (IF34.661) 2017-03-24 Author: Martin Guilliams
Macrophages were first identified in transparent starfish larvae (Astropecten pentacanthus) more than a century ago, so it is fitting that a new function for macrophages would again be discovered in transparent marine larvae, this time from zebra fish (Danio rerio). On page 1317 of this issue, Eom and Parichy (1) reveal a wholly unexpected tissue-specific function of macrophages—their cardinal role in long-distance communication between nonimmune cells. In doing so, macrophages choreograph the patterning of pigment cells that eventually form the stripes on zebrafish.
[Feature] Fishy business Science (IF34.661) 2017-03-24 Author: Martin Enserink
Two Swedish fish researchers, with the aid of five colleagues elsewhere in the world, have alleged fraud in a study on the effects of microplastics on larval fish published in Science by two scientists at Uppsala University (UU) in June 2016. The study supposedly took place at the Ar Research Station in Gotland, but the whistleblowers say it never happened, based on eyewitness testimony and other evidence. A preliminary investigation by UU dismissed the claims in August 2016; a second investigation, by an expert panel at Sweden's Central Ethical Review Board, is still ongoing. An expert hired by that panel filed a more damning report last February that raised the possibility of fraud. Now, both sides are awaiting the expert panel's final verdict, which may influence an ongoing debate about how Swedish institutions investigate research misconduct.
[In Depth] Tweak makes U.S. nukes more precise—and deadlier Science (IF34.661) 2017-03-24 Author: Eliot Marshall
A small fix made in the name of "stockpile stewardship" is turning U.S. submarine–launched missiles into more precise weapons. An improved mechanism installed in aging warhead now makes it possible to adjust the height at which they detonate, according to three experts writing in The Bulletin of the Atomic Scientists. This vastly increases the weapons' efficiency, the experts say, creating the impression that submarine-launched weapons could be used in a first strike against Russia's fixed missile silos. About 500 such warheads have been deployed on submarines; more than 1000 updated warheads are in production. The innovation could create "a deeply destabilizing and dangerous strategic nuclear situation," the authors warn.
[In Depth] In search for unseen matter, physicists turn to dark sector Science (IF34.661) 2017-03-24 Author: Adrian Cho
Scientists hunting unseen dark matter are looking deeper into the shadows. With searches for a favored dark matter candidate—weakly interacting massive particles (WIMPs)—coming up empty, physicists are now turning to the hypothetical "dark sector": an entire shadow realm of hidden particles. This week, physicists will meet at the University of Maryland in College Park for a workshop, sponsored by the U.S. Department of Energy (DOE), to mull ideas for a possible $10 million short-term experiment that would complement the agency's current WIMP search and other dark-matter efforts. And many researchers believe DOE should focus on the dark sector. Whereas WIMPs would be a single massive particle tacked onto the standard model of known particles, the dark sector would consist of a slew of lighter particles and forces—such as a dark version of electromagnetism—with tenuous connections to known particles. To spot dark-sector particles, physicists will have to rethink their detection techniques, but the new experiment could be small and cheap, physicists say. Still, DOE officials warn that the $10 million isn't a sure thing.
[In Depth] New Zealand temblor points to threat of compound quakes Science (IF34.661) 2017-03-24 Author: Betsy Mason
A reassuring rule of thumb about earthquakes is breaking down. For decades, seismologists had assumed that individual faults—as well as isolated segments of longer faults—rupture independently of one another. That limits the maximum size of the potential earthquake that a fault zone can generate. But the magnitude-7.8 earthquake that struck New Zealand just after midnight on 14 November 2016—among the largest in the islands' modern history—has reduced that thinking to rubble. According to a new study, published online this week in Science, the heavy shaking in the Kaikoura quake was amassed by ruptures on at least 12 different faults, in some cases so far apart that they were thought to be immune to each other's influence.
[In Depth] Ma, where did they put T. rex? Science (IF34.661) 2017-03-24 Author: Carolyn Gramling
A new study gives the long-standing dinosaur family tree an overhaul. Based on analyses of hundreds of traits gleaned from existing studies and fossils, the study strikes down a fundamental split of dinosaurs into "bird-hipped" and "reptile-hipped"; it also shifts the charismatic theropods—the group that includes Tyrannosaurus rex and eventually gave rise to birds—to a new spot on the tree, closer to the bird-hipped dinos. The reorganization of the tree suggests that hypercarnivory evolved in different groups through convergent evolution, and may upend the picture of where dinosaurs arose. But don't throw out your dog-eared dino books just yet, other researchers caution: This new family tree is likely to be debated for some time to come.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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