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Dark matter

Alessandro Cuoco, Michael Krämer, Michael Korsmeier
We evaluate dark matter (DM) limits from cosmic-ray antiproton observations using the recent precise AMS-02 measurements. We properly take into account cosmic-ray propagation uncertainties, fitting DM and propagation parameters at the same time and marginalizing over the latter. We find a significant indication of a DM signal for DM masses near 80 GeV, with a hadronic annihilation cross section close to the thermal value, ⟨σv⟩≈3×10^{-26}  cm^{3} s^{-1}. Intriguingly, this signal is compatible with the DM interpretation of the Galactic center gamma-ray excess...
May 12, 2017: Physical Review Letters
Ming-Yang Cui, Qiang Yuan, Yue-Lin Sming Tsai, Yi-Zhong Fan
Using the latest AMS-02 cosmic-ray antiproton flux data, we search for a potential dark matter annihilation signal. The background parameters about the propagation, source injection, and solar modulation are not assumed a priori but based on the results inferred from the recent B/C ratio and proton data measurements instead. The possible dark matter signal is incorporated into the model self-consistently under a Bayesian framework. Compared with the astrophysical background-only hypothesis, we find that a dark matter signal is favored...
May 12, 2017: Physical Review Letters
Stephen Hayes, Jennifer Mahony, Arjen Nauta, Douwe van Sinderen
Bacteriophages are ubiquitous and numerous parasites of bacteria and play a critical evolutionary role in virtually every ecosystem, yet our understanding of the extent of the diversity and role of phages remains inadequate for many ecological niches, particularly in cases in which the host is unculturable. During the past 15 years, the emergence of the field of viral metagenomics has drastically enhanced our ability to analyse the so-called viral 'dark matter' of the biosphere. Here, we review the evolution of viral metagenomic methodologies, as well as providing an overview of some of the most significant applications and findings in this field of research...
May 24, 2017: Viruses
E Bagnaschi, M Borsato, K Sakurai, O Buchmueller, R Cavanaugh, V Chobanova, M Citron, J C Costa, A De Roeck, M J Dolan, J R Ellis, H Flächer, S Heinemeyer, G Isidori, M Lucio, F Luo, D Martínez Santos, K A Olive, A Richards, G Weiglein
We perform a likelihood analysis of the minimal anomaly-mediated supersymmetry-breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that either a wino-like or a Higgsino-like neutralino LSP, [Formula: see text], may provide the cold dark matter (DM), both with similar likelihoods. The upper limit on the DM density from Planck and other experiments enforces [Formula: see text] after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the [Formula: see text], the measured value of the Higgs mass favours a limited range of [Formula: see text] (and also for [Formula: see text] if [Formula: see text]) but the scalar mass [Formula: see text] is poorly constrained...
2017: European Physical Journal. C, Particles and Fields
Jake Lin, Lenka Kramna, Reija Autio, Heikki Hyöty, Matti Nykter, Ondrej Cinek
BACKGROUND: Next generation sequencing (NGS) technology allows laboratories to investigate virome composition in clinical and environmental samples in a culture-independent way. There is a need for bioinformatic tools capable of parallel processing of virome sequencing data by exactly identical methods: this is especially important in studies of multifactorial diseases, or in parallel comparison of laboratory protocols. RESULTS: We have developed a web-based application allowing direct upload of sequences from multiple virome samples using custom parameters...
May 15, 2017: BMC Genomics
D R Gulevich, D Yudin, D V Skryabin, I V Iorsh, I A Shelykh
Matter in nontrivial topological phase possesses unique properties, such as support of unidirectional edge modes on its interface. It is the existence of such modes which is responsible for the wonderful properties of a topological insulator - material which is insulating in the bulk but conducting on its surface, along with many of its recently proposed photonic and polaritonic analogues. We show that exciton-polariton fluid in a nontrivial topological phase in kagome lattice, supports nonlinear excitations in the form of solitons built up from wavepackets of topological edge modes - topological edge solitons...
May 11, 2017: Scientific Reports
N Abgrall, I J Arnquist, F T Avignone, A S Barabash, F E Bertrand, A W Bradley, V Brudanin, M Busch, M Buuck, T S Caldwell, Y-D Chan, C D Christofferson, P-H Chu, C Cuesta, J A Detwiler, C Dunagan, Yu Efremenko, H Ejiri, S R Elliott, T Gilliss, G K Giovanetti, J Goett, M P Green, J Gruszko, I S Guinn, V E Guiseppe, C R S Haufe, R Henning, E W Hoppe, S Howard, M A Howe, B R Jasinski, K J Keeter, M F Kidd, S I Konovalov, R T Kouzes, A M Lopez, J MacMullin, R D Martin, R Massarczyk, S J Meijer, S Mertens, C O'Shaughnessy, A W P Poon, D C Radford, J Rager, A L Reine, K Rielage, R G H Robertson, B Shanks, M Shirchenko, A M Suriano, D Tedeschi, J E Trimble, R L Varner, S Vasilyev, K Vetter, K Vorren, B R White, J F Wilkerson, C Wiseman, W Xu, E Yakushev, C-H Yu, V Yumatov, I Zhitnikov, B X Zhu
We present new limits on exotic keV-scale physics based on 478 kg d of Majorana Demonstrator commissioning data. Constraints at the 90% confidence level are derived on bosonic dark matter (DM) and solar axion couplings, Pauli exclusion principle violating (PEPV) decay, and electron decay using monoenergetic peak signal limits above our background. Our most stringent DM constraints are set for 11.8 keV mass particles, limiting g_{Ae}<4.5×10^{-13} for pseudoscalars and (α^{'}/α)<9.7×10^{-28} for vectors...
April 21, 2017: Physical Review Letters
Aaron D Ludlow, Alejandro Benítez-Llambay, Matthieu Schaller, Tom Theuns, Carlos S Frenk, Richard Bower, Joop Schaye, Robert A Crain, Julio F Navarro, Azadeh Fattahi, Kyle A Oman
We analyze the total and baryonic acceleration profiles of a set of well-resolved galaxies identified in the eagle suite of hydrodynamic simulations. Our runs start from the same initial conditions but adopt different prescriptions for unresolved stellar and active galactic nuclei feedback, resulting in diverse populations of galaxies by the present day. Some of them reproduce observed galaxy scaling relations, while others do not. However, regardless of the feedback implementation, all of our galaxies follow closely a simple relationship between the total and baryonic acceleration profiles, consistent with recent observations of rotationally supported galaxies...
April 21, 2017: Physical Review Letters
Hironao Miyatake, Mathew S Madhavacheril, Neelima Sehgal, Anže Slosar, David N Spergel, Blake Sherwin, Alexander van Engelen
We measure the gravitational lensing shear signal around dark matter halos hosting constant mass galaxies using light sources at z∼1 (background galaxies) and at the surface of last scattering at z∼1100 (the cosmic microwave background). The galaxy shear measurement uses data from the CFHTLenS survey, and the microwave background shear measurement uses data from the Planck satellite. The ratio of shears from these cross-correlations provides a purely geometric distance measurement across the longest possible cosmological lever arm...
April 21, 2017: Physical Review Letters
Bertjan Broeksema, Magdalena Calusinska, Fintan McGee, Klaas Winter, Francesco Bongiovanni, Xavier Goux, Paul Wilmes, Philippe Delfosse, Mohammad Ghoniem
BACKGROUND: Recent advances in high-throughput sequencing allow for much deeper exploitation of natural and engineered microbial communities, and to unravel so-called "microbial dark matter" (microbes that until now have evaded cultivation). Metagenomic analyses result in a large number of genomic fragments (contigs) that need to be grouped (binned) in order to reconstruct draft microbial genomes. While several contig binning algorithms have been developed in the past 2 years, they often lack consensus...
May 2, 2017: BMC Bioinformatics
Branden B Johnson
Publicized disputes between groups of scientists may force lay choices about groups' credibility. One possible, little studied, credibility cue is vote-counting (proportions of scientists on either side): for example, "97%" of climate scientists believe in anthropogenic climate change. An online sample of 2600 Americans read a mock article about a scientific dispute, in a 13 (proportions: 100%-0%, 99%-1%, … 50%-50%, … 1%-99%, 0%-100% for Positions A and B, respectively) × 8 (scenarios: for example, dietary salt, dark matter) between-person experiment...
April 1, 2017: Public Understanding of Science
Suzanne Dikker, Lu Wan, Ido Davidesco, Lisa Kaggen, Matthias Oostrik, James McClintock, Jess Rowland, Georgios Michalareas, Jay J Van Bavel, Mingzhou Ding, David Poeppel
The human brain has evolved for group living [1]. Yet we know so little about how it supports dynamic group interactions that the study of real-world social exchanges has been dubbed the "dark matter of social neuroscience" [2]. Recently, various studies have begun to approach this question by comparing brain responses of multiple individuals during a variety of (semi-naturalistic) tasks [3-15]. These experiments reveal how stimulus properties [13], individual differences [14], and contextual factors [15] may underpin similarities and differences in neural activity across people...
May 8, 2017: Current Biology: CB
Ikechukwu Agomoh, Xiying Hao, Francis Zvomuya
Repeated uptake of excess nutrients by crops in soils with a long history of manure application may be a viable option for reducing the nutrient levels. In this greenhouse study, we examined the effectiveness of six 40-day cycles of barley, canola, corn, oat, pea, soybean, and triticale, all grown under two moisture regimes (100% and 50% soil field capacity, SFC), at extracting nitrogen (N) and phosphorus (P) from a Dark Brown Chernozem that had received 180 Mg ha(-1) (wet wt.) of beef cattle feedlot manure annually for 38 years...
April 25, 2017: International Journal of Phytoremediation
Torsten Bringmann, Felix Kahlhoefer, Kai Schmidt-Hoberg, Parampreet Walia
Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the cosmic microwave background and other indirect detection probes. For the frequently studied case of s-wave annihilation, these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation...
April 7, 2017: Physical Review Letters
A Aguilar-Arevalo, D Amidei, X Bertou, M Butner, G Cancelo, A Castañeda Vázquez, B A Cervantes Vergara, A E Chavarria, C R Chavez, J R T de Mello Neto, J C D'Olivo, J Estrada, G Fernandez Moroni, R Gaïor, Y Guardincerri, K P Hernández Torres, F Izraelevitch, A Kavner, B Kilminster, I Lawson, A Letessier-Selvon, J Liao, A Matalon, V B B Mello, J Molina, P Privitera, K Ramanathan, Y Sarkis, T Schwarz, M Settimo, M Sofo Haro, R Thomas, J Tiffenberg, E Tiouchichine, D Torres Machado, F Trillaud, X You, J Zhou
We present direct detection constraints on the absorption of hidden-photon dark matter with particle masses in the range 1.2-30  eV c^{-2} with the DAMIC experiment at SNOLAB. Under the assumption that the local dark matter is entirely constituted of hidden photons, the sensitivity to the kinetic mixing parameter κ is competitive with constraints from solar emission, reaching a minimum value of 2.2×10^{-14} at 17  eV c^{-2}. These results are the most stringent direct detection constraints on hidden-photon dark matter in the galactic halo with masses 3-12  eV c^{-2} and the first demonstration of direct experimental sensitivity to ionization signals <12  eV from dark matter interactions...
April 7, 2017: Physical Review Letters
Hooman Davoudiasl, Christopher W Murphy
A very light boson of mass O(10^{-22})  eV may potentially be a viable dark matter (DM) candidate, which can avoid phenomenological problems associated with cold DM. Such "fuzzy DM (FDM)" may naturally be an axion with a decay constant f_{a}∼10^{16}-10^{18}  GeV and a mass m_{a}∼μ^{2}/f_{a} with μ∼10^{2}  eV. Here, we propose a concrete model, where μ arises as a dynamical scale from infrared confining dynamics, analogous to QCD. Our model is an alternative to the usual approach of generating μ through string theoretic instanton effects...
April 7, 2017: Physical Review Letters
Yanru Shen, Wenyan Zhao, Chunling Zhang, Yujie Shan, Junxian Shi
Streptomycin used in human and veterinary medicine is released into the environment mainly through excretions. As such, its elimination in water should be investigated to control pollution. In this study, the degradation of streptomycin in water was studied, and the influence of variables, including light exposure, solution pH, temperature, ionic strength, dissolved organic matter (DOM), and coexisting surfactants, on degradation was investigated. Streptomycin degradation was consistent with the first-order model in aquatic environments...
April 20, 2017: Environmental Science and Pollution Research International
Zachary Landry, Brandon K Swan, Gerhard J Herndl, Ramunas Stepanauskas, Stephen J Giovannoni
Deep-ocean regions beyond the reach of sunlight contain an estimated 615 Pg of dissolved organic matter (DOM), much of which persists for thousands of years. It is thought that bacteria oxidize DOM until it is too dilute or refractory to support microbial activity. We analyzed five single-amplified genomes (SAGs) from the abundant SAR202 clade of dark-ocean bacterioplankton and found they encode multiple families of paralogous enzymes involved in carbon catabolism, including several families of oxidative enzymes that we hypothesize participate in the degradation of cyclic alkanes...
April 18, 2017: MBio
Toshiyuki Wakimoto
Considering the dynamic features of natural products, our access toward exploring the entire diversity of natural products has been quite limited. It is challenging to assess the diversity of natural products by using conventional analytical methods, even with tandem chromatographic techniques, such as LC-MS and GC-MS. This viewpoint is supported by the sequencing analyses of microbial genomes, which have unveiled the potential of secondary metabolite production far exceeding the number of isolated molecules...
April 18, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Ying Ping Lee, Manabu Fujii, Tetsuro Kikuchi, Masafumi Natsuike, Hiroaki Ito, Toru Watanabe, Chihiro Yoshimura
Ferrous iron (Fe[II]) oxidation by dissolved oxygen was investigated in the Shizugawa Bay watershed with particular attention given to the effect of dissolved organic matter (DOM) properties on Fe(II) oxidation. To cover a wide spectrum of DOM composition, water samples were collected from various water sources including freshwater (e.g., river water and wastewater effluent) and coastal seawater. Measurement of nanomolar Fe(II) oxidation by using luminol chemiluminescence under dark, air-saturated conditions at 25 °C indicated that spatio-temporal variation of the second-order rate constant (6...
April 5, 2017: Chemosphere
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