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  • 1
    Publication Date: 2012-08-04
    Description: Supermassive black holes (SMBHs; mass is greater than or approximately 10(5) times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reis, R C -- Miller, J M -- Reynolds, M T -- Gultekin, K -- Maitra, D -- King, A L -- Strohmayer, T E -- New York, N.Y. -- Science. 2012 Aug 24;337(6097):949-51. doi: 10.1126/science.1223940. Epub 2012 Aug 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA. rdosreis@umich.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22859817" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-09-28
    Description: "Jake_M," the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (〉15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stolper, E M -- Baker, M B -- Newcombe, M E -- Schmidt, M E -- Treiman, A H -- Cousin, A -- Dyar, M D -- Fisk, M R -- Gellert, R -- King, P L -- Leshin, L -- Maurice, S -- McLennan, S M -- Minitti, M E -- Perrett, G -- Rowland, S -- Sautter, V -- Wiens, R C -- MSL Science Team -- New York, N.Y. -- Science. 2013 Sep 27;341(6153):1239463. doi: 10.1126/science.1239463.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Caltech, Pasadena, CA 91125, USA. ems@gps.caltech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24072927" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2013-12-11
    Description: Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McLennan, S M -- Anderson, R B -- Bell, J F 3rd -- Bridges, J C -- Calef, F 3rd -- Campbell, J L -- Clark, B C -- Clegg, S -- Conrad, P -- Cousin, A -- Des Marais, D J -- Dromart, G -- Dyar, M D -- Edgar, L A -- Ehlmann, B L -- Fabre, C -- Forni, O -- Gasnault, O -- Gellert, R -- Gordon, S -- Grant, J A -- Grotzinger, J P -- Gupta, S -- Herkenhoff, K E -- Hurowitz, J A -- King, P L -- Le Mouelic, S -- Leshin, L A -- Leveille, R -- Lewis, K W -- Mangold, N -- Maurice, S -- Ming, D W -- Morris, R V -- Nachon, M -- Newsom, H E -- Ollila, A M -- Perrett, G M -- Rice, M S -- Schmidt, M E -- Schwenzer, S P -- Stack, K -- Stolper, E M -- Sumner, D Y -- Treiman, A H -- VanBommel, S -- Vaniman, D T -- Vasavada, A -- Wiens, R C -- Yingst, R A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1244734. doi: 10.1126/science.1244734. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geosciences, State University of New York, Stony Brook, NY 11794, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324274" target="_blank"〉PubMed〈/a〉
    Keywords: Bays ; Calcium Sulfate/analysis/chemistry ; Chlorine/analysis/chemistry ; *Exobiology ; Extraterrestrial Environment/*chemistry ; Ferrosoferric Oxide/analysis/chemistry ; Geologic Sediments/*chemistry ; Halogens/analysis/chemistry ; Hydrogen-Ion Concentration ; Iron/analysis/chemistry ; Magnesium/analysis/chemistry ; *Mars ; Silicates/analysis/chemistry ; Water/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2016-03-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McNutt, Marcia -- Lehnert, Kerstin -- Hanson, Brooks -- Nosek, Brian A -- Ellison, Aaron M -- King, John Leslie -- New York, N.Y. -- Science. 2016 Mar 4;351(6277):1024-6. doi: 10.1126/science.aad7048. Epub 2016 Mar 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Editor-in-Chief, Science, Washington, DC 20005 USA. mmcnutt@aaas.org. ; Columbia University, Palisades, NY 10964 USA. ; American Geophysical Union, Washington, DC 20009 USA. ; University of Virginia and Center for Open Science, Charlottesville, VA 22903 USA. ; Harvard University, Petersham, MA 01366 USA. ; University of Michigan, Ann Arbor, MI 48109 USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26941302" target="_blank"〉PubMed〈/a〉
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2011-12-17
    Description: Hox proteins are a metazoan-specific family of transcription factors that are required for developmental patterning. The genomic arrangement of Hox genes into four paralogous clusters is a primitive feature of jawed vertebrates. By using high-throughput sequencing, we demonstrate the absence of all HoxC transcripts from embryos of the shark Scyliorhinus canicula and the skate Leucoraja erinacea and the absence of all HoxC genes and two HoxC-associated microRNAs from the genome of L. erinacea. These data suggest a loss of the entire HoxC cluster in elasmobranch fishes and represent evidence for the natural deletion of an entire Hox cluster in vertebrates.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264428/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264428/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉King, Benjamin L -- Gillis, J Andrew -- Carlisle, Heather R -- Dahn, Randall D -- P20 RR016463/RR/NCRR NIH HHS/ -- P20 RR016463-12/RR/NCRR NIH HHS/ -- P20RR016463/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 2011 Dec 16;334(6062):1517. doi: 10.1126/science.1210912.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Kathryn W. Davis Center for Regenerative Biology and Medicine, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, USA. bking@mdibl.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22174244" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Gene Deletion ; Gene Silencing ; Homeodomain Proteins/*genetics ; MicroRNAs/genetics ; Multigene Family ; Sharks/*genetics ; Skates (Fish)/*genetics
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2013-11-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bolukbasi, Burcu -- Berente, Nicholas -- Cutcher-Gershenfeld, Joel -- Dechurch, Leslie -- Flint, Courtney -- Haberman, Michael -- King, John Leslie -- Knight, Eric -- Lawrence, Barbara -- Masella, Ethan -- McElroy, Charles -- Mittleman, Barbara -- Nolan, Mark -- Radik, Melanie -- Shin, Namchul -- Thompson, Cheryl A -- Winter, Susan -- Zaslavsky, Ilya -- Allison, M Lee -- Arctur, David -- Arrigo, Jennifer -- Aufdenkampe, Anthony K -- Bass, Jay -- Crowell, Jim -- Daniels, Mike -- Diggs, Stephen -- Duffy, Christopher -- Gil, Yolanda -- Gomez, Basil -- Graves, Sara -- Hazen, Robert -- Hsu, Leslie -- Kinkade, Danie -- Lehnert, Kerstin -- Marone, Chris -- Middleton, Don -- Noren, Anders -- Pearthree, Genevieve -- Ramamurthy, Mohan -- Robinson, Erin -- Percivall, George -- Richard, Stephen -- Suarez, Celina -- Walker, Doug -- New York, N.Y. -- Science. 2013 Nov 29;342(6162):1041-2. doi: 10.1126/science.342.6162.1041-b.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Labor and Employment Relations, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24288316" target="_blank"〉PubMed〈/a〉
    Keywords: *Access to Information ; Periodicals as Topic/*economics ; Research/*economics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Thirty small upland lakes in Cumbria, Wales, Scotland and Northern Ireland were each visited once during June and July 2000. From each lake, samples of surface sediment epilithon, macrophytes and total dissolved nitrogen (TDN) were collected for nitrogen stable isotope analysis. As part of a wider programme, samples were also collected for chemical analysis and bioassays.2. Considerable variation was found in δ15N values in all measured nitrogen compartments. Some regional variation was evident but was generally weak. Sediment and epilithon δ15N were positively correlated with δ15N of TDN, suggesting that baseline nitrogen isotope ratios influence those in some organic matter compartments in the lakes.3. Sediment δ15N was higher when inorganic nitrogen concentration in the water was low, possibly reflecting reduced isotope fractionation under these conditions. However, this was not the case for epilithon or macrophytes. Sediment δ15N values were also negatively related to annual nitrogen deposition.4. Sediment, epilithon and macrophyte δ15N values all showed significant relations to nutrient limitation in the lakes as determined by algal bioassays. We suggest that sediment δ15N might be developed as a simple integrating measure of the degree of nitrogen limitation in lakes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Thirty small upland lakes in Cumbria, Wales, Scotland and Northern Ireland were visited three times between April and August 2000. On each occasion water chemistry was measured and phytoplankton bioassays were performed in the laboratory to assess growth-rate and yield limitation by phosphorus and nitrogen. In addition, yield limitation of periphyton growth was investigated twice, in situ, using nutrient-diffusing substrata.2. Over the whole season the percentage frequency of P, N and co-limitation was 24, 13 and 63%, respectively, for phytoplankton rate limitation and 20, 22 and 58%, respectively, for phytoplankton yield limitation.3. A clear response of periphyton yield to nutrient additions was found in 75% of all cases and of these, co-limitation was most common (54%). Average percentage frequency for P and N limitation was 26 and 20%, respectively.4. Phytoplankton and periphyton showed seasonal changes in nutrient limitation within sites. In particular, co-limitation became progressively more common as the season progressed.5. The response of phytoplankton growth rate to ammonium and nitrate addition was identical, but ammonium was a slightly better source of nitrogen than nitrate for phytoplankton yield on 7% and for periphyton yield on 10% of the occasions. However, the magnitude of the effect was small.6. The concentration of dissolved inorganic nitrogen (DIN) and the molar ratio of DIN to total dissolved phosphorus (TDP), appeared to be the main environmental factors controlling the extent of nitrogen or phosphorus limitation at a given site. Nitrogen limitation was more likely than phosphorus limitation where the DIN was 〈6.5 mmol m−3 and the ratio of DIN : TDP was 〈53. Co-limitation was the most likely outcome at a DIN concentration 〈13 mmol m−3 and at a DIN : TDP molar ratio 〈250. Above these values phosphorus limitation was most likely.7. The relatively high frequency of nitrogen limitation and co-limitation at higher N : P ratios than previously reported, may result from the inability of nitrogen-fixing cyanobacteria to thrive in these upland lakes where pH and the concentration of phosphorus tended to be low and where flushing rates tended to be high.
    Type of Medium: Electronic Resource
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