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Dark matter

Marija Jakovljevic, Irena Lavrnja, Iva Bozic, Danijela Savic, Ivana Bjelobaba, Sanja Pekovic, Jean Sévigny, Nadezda Nedeljkovic, Danijela Laketa
The present study explores tissue and cellular distribution of ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) and the gene and protein expression in rat spinal cord during the course of experimental autoimmune encephalomyelitis (EAE). Given that NTPDase2 hydrolyzes ATP with a transient accumulation of ADP, the expression of ADP-sensitive P2 purinoceptors was analyzed as well. The autoimmune disease was actively induced in Dark Agouti female rats and the changes were analyzed 10, 15 and 29 days after the induction...
2017: Frontiers in Cellular Neuroscience
(no author information available yet)
No abstract text is available yet for this article.
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
S François, D Filloux, M Frayssinet, P Roumagnac, D P Martin, M Ogliastro, R Froissart
Metagenomics studies have revolutionized the field of biology by revealing the presence of many previously unisolated and uncultured micro-organisms. However, one of the main problems encountered in metagenomic studies is the high percentage of sequences that cannot be assigned taxonomically using commonly used similarity-based approaches (e.g. BLAST or HMM). These unassigned sequences are allegorically called « dark matter » in the metagenomic literature and are often referred to as being derived from new or unknown organisms...
November 14, 2017: Virus Research
A U Abeysekara, A Albert, R Alfaro, C Alvarez, J D Álvarez, R Arceo, J C Arteaga-Velázquez, D Avila Rojas, H A Ayala Solares, A S Barber, N Bautista-Elivar, A Becerril, E Belmont-Moreno, S Y BenZvi, D Berley, A Bernal, J Braun, C Brisbois, K S Caballero-Mora, T Capistrán, A Carramiñana, S Casanova, M Castillo, U Cotti, J Cotzomi, S Coutiño de León, C De León, E De la Fuente, B L Dingus, M A DuVernois, J C Díaz-Vélez, R W Ellsworth, K Engel, O Enríquez-Rivera, D W Fiorino, N Fraija, J A García-González, F Garfias, M Gerhardt, A González Muñoz, M M González, J A Goodman, Z Hampel-Arias, J P Harding, S Hernández, A Hernández-Almada, J Hinton, B Hona, C M Hui, P Hüntemeyer, A Iriarte, A Jardin-Blicq, V Joshi, S Kaufmann, D Kieda, A Lara, R J Lauer, W H Lee, D Lennarz, H León Vargas, J T Linnemann, A L Longinotti, G Luis Raya, R Luna-García, R López-Coto, K Malone, S S Marinelli, O Martinez, I Martinez-Castellanos, J Martínez-Castro, H Martínez-Huerta, J A Matthews, P Miranda-Romagnoli, E Moreno, M Mostafá, L Nellen, M Newbold, M U Nisa, R Noriega-Papaqui, R Pelayo, J Pretz, E G Pérez-Pérez, Z Ren, C D Rho, C Rivière, D Rosa-González, M Rosenberg, E Ruiz-Velasco, H Salazar, F Salesa Greus, A Sandoval, M Schneider, H Schoorlemmer, G Sinnis, A J Smith, R W Springer, P Surajbali, I Taboada, O Tibolla, K Tollefson, I Torres, T N Ukwatta, G Vianello, T Weisgarber, S Westerhoff, I G Wisher, J Wood, T Yapici, G Yodh, P W Younk, A Zepeda, H Zhou, F Guo, J Hahn, H Li, H Zhang
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed...
November 17, 2017: Science
Alyse K Hawley, Masaru K Nobu, Jody J Wright, W Evan Durno, Connor Morgan-Lang, Brent Sage, Patrick Schwientek, Brandon K Swan, Christian Rinke, Monica Torres-Beltrán, Keith Mewis, Wen-Tso Liu, Ramunas Stepanauskas, Tanja Woyke, Steven J Hallam
Microbial communities drive biogeochemical cycles through networks of metabolite exchange that are structured along energetic gradients. As energy yields become limiting, these networks favor co-metabolic interactions to maximize energy disequilibria. Here we apply single-cell genomics, metagenomics, and metatranscriptomics to study bacterial populations of the abundant "microbial dark matter" phylum Marinimicrobia along defined energy gradients. We show that evolutionary diversification of major Marinimicrobia clades appears to be closely related to energy yields, with increased co-metabolic interactions in more deeply branching clades...
November 15, 2017: Nature Communications
Sara Letzner, Onur Güntürkün, Stephanie Lor, Robert Jan Pawlik, Martina Manns
The ontogenetic mechanisms leading to complementary hemispheric specialisations of the two brain halves are poorly understood. In pigeons, asymmetrical light stimulation during development triggers the left-hemispheric dominance for visuomotor control but light effects on right-hemispheric specialisations are largely unknown. We therefore tested adult pigeons with and without embryonic light experience in a visual search task in which the birds pecked peas regularly scattered on an area in front of them. Comparing the pecking pattern of both groups indicates that the embryonic light conditions differentially influence biased visuospatial attention under mono- and binocular seeing conditions...
November 14, 2017: Scientific Reports
Gonzalo V Gomez-Saez, Anika M Pohlabeln, Aron Stubbins, Chris M Marsay, Thorsten Dittmar
Sulfidic sediments are a source of dissolved organic sulfur (DOS) to the ocean but the fate of sedimentary DOS in the oxic, sunlit water column is unknown. We hypothesized that photodegradation after discharge from the dark sedimentary environment results in DOS molecular transformation and decomposition. To test this hypothesis, sulfidic porewater from a saltmarsh was exposed to potential abiotic transformations of dissolved organic matter (DOM) in the water column. We quantitatively investigated DOM transformations via elemental analysis and molecularly via ultrahigh-resolution mass spectrometry...
November 14, 2017: Environmental Science & Technology
Elisa Guerrero-Feijóo, Eva Sintes, Gerhard J Herndl, Marta M Varela
Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production throughout the water column, however, more prominently in the bathypelagic waters. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) allowed us to identify several microbial groups involved in dark DIC uptake...
November 10, 2017: Environmental Microbiology
Caterina Braggio, Giovanni Carugno, Federico Chiossi, Alberto Di Lieto, Marco Guarise, Pasquale Maddaloni, Antonello Ortolan, Giuseppe Ruoso, Luigi Santamaria, Jordanka Tasseva, Mauro Tonelli
We present a detection scheme to search for QCD axion dark matter, that is based on a direct interaction between axions and electrons explicitly predicted by DFSZ axion models. The local axion dark matter field shall drive transitions between Zeeman-split atomic levels separated by the axion rest mass energy m a c (2). Axion-related excitations are then detected with an upconversion scheme involving a pump laser that converts the absorbed axion energy (~hundreds of μeV) to visible or infrared photons, where single photon detection is an established technique...
November 9, 2017: Scientific Reports
Elizabeth Gibney
No abstract text is available yet for this article.
November 8, 2017: Nature
Alan T Bull, Hamidah Idris, Roy Sanderson, Juan Asenjo, Barbara Andrews, Michael Goodfellow
The data reported in this paper are among the first relating to the microbiology of hyper-arid, very high altitude deserts and they provide base line information on the structure of actinobacterial communities. The high mountain Cerro Chajnantor landscape of the Central Andes in northern Chile is exposed to the world's most intense levels of solar radiation and its impoverished soils are severely desiccated. The purpose of this research was to define the actinobacterial community structures in soils at altitudes ranging from 3000 to 5000 m above sea level...
November 3, 2017: Extremophiles: Life Under Extreme Conditions
Doojin Kim, Jong-Chul Park, Seodong Shin
We propose a novel dark matter (DM) detection strategy for models with a nonminimal dark sector. The main ingredients in the underlying DM scenario are a boosted DM particle and a heavier dark sector state. The relativistic DM impinged on target material scatters off inelastically to the heavier state, which subsequently decays into DM along with lighter states including visible (standard model) particles. The expected signal event, therefore, accompanies a visible signature by the secondary cascade process associated with a recoiling of the target particle, differing from the typical neutrino signal not involving the secondary signature...
October 20, 2017: Physical Review Letters
Man Ho Chan, Chung Hei Leung
Recently, some very tight constraints of annihilating dark matter have been obtained from gamma-ray data of the Milky Way and Milky Way dwarf spheroidal satellite galaxies. In this article, we report that there are two excellent galaxy clusters (A2877 and Fornax) which can provide interesting constraints for annihilating dark matter. The lower limits of the dark matter mass for the thermal relic annihilation cross section are 25 GeV, 6 GeV, 130 GeV and 100 GeV respectively for the e (+) e (-), μ (+) μ (-), τ (+) τ (-) and [Formula: see text] channels...
November 2, 2017: Scientific Reports
Adam Mann
No abstract text is available yet for this article.
October 31, 2017: Proceedings of the National Academy of Sciences of the United States of America
Nadine Meyer, Harry Proud, Marisa Perea-Ortiz, Charlotte O'Neale, Mathis Baumert, Michael Holynski, Jochen Kronjäger, Giovanni Barontini, Kai Bongs
Jones-Roberts solitons are the only known class of stable dark solitonic solutions of the nonlinear Schrödinger equation in two and three dimensions. They feature a distinctive elongated elliptical shape that allows them to travel without change of form. By imprinting a triangular phase pattern, we experimentally generate two-dimensional Jones-Roberts solitons in a three-dimensional atomic Bose-Einstein condensate. We monitor their dynamics, observing that this kind of soliton is indeed not affected by dynamic (snaking) or thermodynamic instabilities, that instead make other classes of dark solitons unstable in dimensions higher than one...
October 13, 2017: Physical Review Letters
Kai Liao, Xi-Long Fan, Xuheng Ding, Marek Biesiada, Zong-Hong Zhu
The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10(4)-10(5) gravitational wave detections per year, 50-100 of which will be lensed. Here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain...
October 27, 2017: Nature Communications
Daniel Fels
Studies confirm physical long-range cell-cell communication, most evidently based on electromagnetic fields. Effects concern induction or inhibition of cell growth. Their natural function is unclear. With the protozoan Paramecium caudatum I tested whether the signals regulate cell density and are electromagnetic. Up to 300 cells/mL, cell growth in clones of this study is decreasingly pronounced. Using cuvettes as chemical barriers enabling physical communication  I  placed 5 indicator cells/mL, the inducer populations, into smaller cuvettes that stand in bigger and contained 50, 100, 200 or 300 cells/mL...
October 23, 2017: Scientific Reports
Kenneth W Ellens, Nils Christian, Charandeep Singh, Venkata P Satagopam, Patrick May, Carole L Linster
The post-genomic era has provided researchers with a deluge of protein sequences. However, a significant fraction of the proteins encoded by sequenced genomes remains without an identified function. Here, we aim at determining how many enzymes of uncertain or unknown function are still present in the Saccharomyces cerevisiae and human proteomes. Using information available in the Swiss-Prot, BRENDA and KEGG databases in combination with a Hidden Markov Model-based method, we estimate that >600 yeast and 2000 human proteins (>30% of their proteins of unknown function) are enzymes whose precise function(s) remain(s) to be determined...
November 16, 2017: Nucleic Acids Research
Xiaowen Hu, Anil K Sood, Chi V Dang, Lin Zhang
Sequencing technology has facilitated a new era of cancer research, especially in cancer genomics. Using next-generation sequencing, thousands of long noncoding RNAs (lncRNAs) have been identified as abnormally altered in the cancer genome or differentially expressed in tumor tissues. These lncRNAs are associated with imbalanced gene regulation and aberrant biological processes that contribute to malignant transformation. The functions and therapeutic potential of cancer-related lncRNAs have attracted considerable interest in the past few years...
October 17, 2017: Current Opinion in Genetics & Development
Satoshi Iso, Pasquale D Serpico, Kengo Shimada
If the electroweak sector of the standard model is described by classically conformal dynamics, the early Universe evolution can be substantially altered. It is already known that-contrarily to the standard model case-a first-order electroweak phase transition may occur. Here we show that, depending on the model parameters, a dramatically different scenario may happen: A first-order, six massless quark QCD phase transition occurs first, which then triggers the electroweak symmetry breaking. We derive the necessary conditions for this dynamics to occur, using the specific example of the classically conformal B-L model...
October 6, 2017: Physical Review Letters
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