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  • 1
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    Physical processes and zooplankton distribution in the Great South Channel : observational and numerical studies (2012)
    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 1995
    Description: This thesis addresses the question, "How do small-scale physics and biology combine to produce dense aggregations of certain species of zooplankton in the Great South Channel (GSC) of the Gulf of Maine?" The thesis consists of three relatively independent parts: an observational study made while following two right whales as they fed on dense patches of the copepod Galanus finmarchicus in the northern GSC; a detailed description of a tightly integrated set of biological and physical observations made in the GSC by means of a new instrument, the Video Plankton Recorder (VPR); and a two-dimensional Eulerian numerical model that simulates one way in which a physical flow field, combined with a biological behavior pattern, may produce dense plankton patches at a convergent front. Part I: Data from a wide variety of instruments was combined to produce a coherent picture of the physical and biological environment near two feeding right whales observed in June, 1989. Instruments included a CTD (with transmissometer), a MOCNESS net system, a 150-kHz ADCP, and a towed acoustic plankton profiler operating at 120 and 200 kHz. Acoustic data were intercalibrated with net-tow data and with "noise" in the transmissometer signal in order to estimate copepod abundance in the plankton patches on which the whales were feeding. One of the whales was observed to reverse course when copepod abundance dropped below about 1.5- 4.5 x 103 copepods/m3 , which is consistent with independent estimates of the density of copepods necessary for a right whale to gain more energy from the prey it ingests than it loses to the extra hydrodynamic drag it experiences while feeding. Part II: The VPR is a towed underwater microscope designed to image plankton non-invasively with sufficient resolution to obtain information on the spatial distribut ion of organisms on scales ranging from millimeters to hundreds of kilometers. CTD instrumentation mounted on the VPR makes it possible to correlate biological and hydrographic data with great precision. This study reports data from one transect made across the GSC in May, 1992. The data show close correlations between hydrographic features (such as fronts, plumes and water masses) and broad-scale plankton distribution. In addition, it was possible to correlate the fine-scale (order tens of meters) patchiness in plankton distribution with the local stability of the water column (as indicated by gradient Richardson number). In one case, biological data provided an aid in determining the origin of one of the observed water masses. Part III: This chapter presents a two-dimensional Eulerian numerical model that shows how depth-keeping swimming behavior on the part of an organism, combined with a convergent flow field at a surface front , can create dense patches of the organism. In this model a steady-state flow field and vertical diffusivity field are prescribed, along with the initial distribution of the plankton. The plankton swim vertically with speeds that depend only on depth, but the form of that depth-dependence may take into account such factors as the vertical variation in light level or in the concentration of some prey organism. An analysis of various nondimensional parameters associated with the model illustrates the roles played in determining the final structure of the patch by such factors as diffusion, water velocity and details of the animals' swimming behavior. Output from the model is compared with data taken at a dense plankton patch observed near a front in the northern Great South Channel in early June, 1989.
    Description: My first three years in the Joint Program were paid for by the Office of Naval Research under an ONR Fellowship. I would also like to acknowledge subsequent support from the National Science Foundation under grant OCE 93-13671 and the National Oceanic and Atmospheric Administration under grants NA36GP0374 and NA26GP0431.
    Keywords: Marine zooplankton ; Marine phytoplankton ; Copepoda ; Food chains ; Marlin (Ship) Cruise ; Endeavor (Ship: 1976-) Cruise EN237
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
    Format: application/pdf
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  • 2
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    A memory retrieval-extinction procedure to prevent drug craving and relapse (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-04-14
    Description: Drug use and relapse involve learned associations between drug-associated environmental cues and drug effects. Extinction procedures in the clinic can suppress conditioned responses to drug cues, but the extinguished responses typically reemerge after exposure to the drug itself (reinstatement), the drug-associated environment (renewal), or the passage of time (spontaneous recovery). We describe a memory retrieval-extinction procedure that decreases conditioned drug effects and drug seeking in rat models of relapse, and drug craving in abstinent heroin addicts. In rats, daily retrieval of drug-associated memories 10 minutes or 1 hour but not 6 hours before extinction sessions attenuated drug-induced reinstatement, spontaneous recovery, and renewal of conditioned drug effects and drug seeking. In heroin addicts, retrieval of drug-associated memories 10 minutes before extinction sessions attenuated cue-induced heroin craving 1, 30, and 180 days later. The memory retrieval-extinction procedure is a promising nonpharmacological method for decreasing drug craving and relapse during abstinence.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3695463/" 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/PMC3695463/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xue, Yan-Xue -- Luo, Yi-Xiao -- Wu, Ping -- Shi, Hai-Shui -- Xue, Li-Fen -- Chen, Chen -- Zhu, Wei-Li -- Ding, Zeng-Bo -- Bao, Yan-ping -- Shi, Jie -- Epstein, David H -- Shaham, Yavin -- Lu, Lin -- Z99 DA999999/Intramural NIH HHS/ -- ZIA DA000434-12/Intramural NIH HHS/ -- New York, N.Y. -- Science. 2012 Apr 13;336(6078):241-5. doi: 10.1126/science.1215070.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Institute on Drug Dependence, Peking University, Beijing, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22499948" target="_blank"〉PubMed〈/a〉
    Keywords: Amygdala/enzymology ; Animals ; Behavior, Addictive/*prevention & control ; Cocaine/administration & dosage ; Cocaine-Related Disorders/*psychology/therapy ; Conditioning, Classical ; Conditioning, Operant ; Cues ; *Extinction, Psychological ; Heroin/administration & dosage ; Heroin Dependence/*psychology/therapy ; Humans ; Male ; *Memory ; Mental Recall ; Models, Animal ; Prefrontal Cortex/enzymology ; Protein Kinase C/metabolism ; Rats ; Rats, Sprague-Dawley ; Recurrence ; Self Administration ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Rab5 is necessary for the biogenesis of the endolysosomal system in vivo (2012)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2012-05-25
    Description: An outstanding question is how cells control the number and size of membrane organelles. The small GTPase Rab5 has been proposed to be a master regulator of endosome biogenesis. Here, to test this hypothesis, we developed a mathematical model of endosome dependency on Rab5 and validated it by titrating down all three Rab5 isoforms in adult mouse liver using state-of-the-art RNA interference technology. Unexpectedly, the endocytic system was resilient to depletion of Rab5 and collapsed only when Rab5 decreased to a critical level. Loss of Rab5 below this threshold caused a marked reduction in the number of early endosomes, late endosomes and lysosomes, associated with a block of low-density lipoprotein endocytosis. Loss of endosomes caused failure to deliver apical proteins to the bile canaliculi, suggesting a requirement for polarized cargo sorting. Our results demonstrate for the first time, to our knowledge, the role of Rab5 as an endosome organizer in vivo and reveal the resilience mechanisms of the endocytic system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zeigerer, Anja -- Gilleron, Jerome -- Bogorad, Roman L -- Marsico, Giovanni -- Nonaka, Hidenori -- Seifert, Sarah -- Epstein-Barash, Hila -- Kuchimanchi, Satya -- Peng, Chang Geng -- Ruda, Vera M -- Del Conte-Zerial, Perla -- Hengstler, Jan G -- Kalaidzidis, Yannis -- Koteliansky, Victor -- Zerial, Marino -- England -- Nature. 2012 May 23;485(7399):465-70. doi: 10.1038/nature11133.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22622570" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Polarity ; Cells, Cultured ; Endocytosis ; Endosomes/*metabolism ; Gene Knockdown Techniques ; Hepatocytes/cytology/metabolism ; Isoenzymes/biosynthesis/deficiency/genetics/metabolism ; Lipoproteins, LDL/metabolism ; Liver/cytology/enzymology/metabolism ; Lysosomes/*metabolism ; Mice ; Multivesicular Bodies/metabolism ; Organ Specificity ; Protein Biosynthesis ; RNA Interference ; RNA, Messenger/analysis/genetics ; Time Factors ; Vesicular Transport Proteins/metabolism ; rab5 GTP-Binding Proteins/biosynthesis/deficiency/genetics/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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