1,754 research outputs found

    Bromostibine complexes of iron(II): hypervalency and reactivity

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    The halostibine complexes [CpFe(CO)2(SbMe2Br)][CF3SO3] and [CpFe(CO)2(SbMe2Br)][BF4] both contain significant interactions between the anion and the formally neutral Sb(III) ligand, which simultaneously displays Lewis acidic and Lewis basic properties. The unexpected secondary product [CpFe(CO)(Me2BrSb-?-Br-SbBrMe2)] is formed in the presence of excess ligand, the strongly associated Br– anion bridging the two Sb donors to form a four-membered FeSb2Br ring.<br/

    The geometry of reaction norms yields insights on classical fitness functions for Great Lakes salmon.

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    Life history theory examines how characteristics of organisms, such as age and size at maturity, may vary through natural selection as evolutionary responses that optimize fitness. Here we ask how predictions of age and size at maturity differ for the three classical fitness functions-intrinsic rate of natural increase r, net reproductive rate R0, and reproductive value Vx-for semelparous species. We show that different choices of fitness functions can lead to very different predictions of species behavior. In one's efforts to understand an organism's behavior and to develop effective conservation and management policies, the choice of fitness function matters. The central ingredient of our approach is the maturation reaction norm (MRN), which describes how optimal age and size at maturation vary with growth rate or mortality rate. We develop a practical geometric construction of MRNs that allows us to include different growth functions (linear growth and nonlinear von Bertalanffy growth in length) and develop two-dimensional MRNs useful for quantifying growth-mortality trade-offs. We relate our approach to Beverton-Holt life history invariants and to the Stearns-Koella categorization of MRNs. We conclude with a detailed discussion of life history parameters for Great Lakes Chinook Salmon and demonstrate that age and size at maturity are consistent with predictions using R0 (but not r or Vx) as the underlying fitness function

    How Captain Amerika uses neural networks to fight crime

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    Artificial neural network models can make amazing computations. These models are explained along with their application in problems associated with fighting crime. Specific problems addressed are identification of people using face recognition, speaker identification, and fingerprint and handwriting analysis (biometric authentication)

    Shark-diving tourism as a financing mechanism for shark conservation strategies in Malaysia

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    This study estimated the economic value of the shark-diving industry in Semporna, the most popular diving destination of Malaysia, by surveying the expenditures of diving tourists and dive operators through the region. A willingness-to-pay survey was also used to estimate the potential of the industry as a financing mechanism for enforcement and management of a hypothetical Marine Protected Area (MPA) to conserve shark populations. The study showed that in 2012, shark-diving tourism provided direct revenues in excess of USD 9.8 million to the Semporna region. These economic benefits had a flow-on effect, generating more than USD 2 million in direct taxes to the government and USD 1.4 million in salaries to the community. A contingent valuation analysis indicated that implementation of a fee paid by divers could generate over USD 2 million for management and enforcement of the MPA each year. These findings suggest that shark diving is an important contributor to the economy of the Semporna region that could be used as a mechanism to assist financial resourcing for management and conservation strategies

    Using WebGIS to Develop a Spatial Bibliography for Organizing, Mapping, and Disseminating Research Information: A Case Study of Quaking Aspen

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    On the Ground • Spatial data is valuable to researchers for locating studies that occur in a particular area of interest, or one with similar attributes. • Without a standard in publishing protocol, spatial data largely goes unreported, or is difficult to find without searching the publication. • Assigning location data and displaying points on a public web map makes locating publications based on spatial location possible

    An empirical study of the psychodynamics of suicide: A preliminary report

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    Preliminary results from a study of psychodynamic constructs are presented based on data from inpatients following a suicide attempt. The study examines the association between four psychodynamic constructs, severity of suicidal intent, and severity of depressive symptomatology in a sample of hospitalized suicide attempters. Higher levels of suicidal intent were associated with less differentiated self and object representations and less emotional investment in relationships. More severe depressive symptoms in suicide attempters were correlated with more self‐targeted anger; less eternally directed anger, higher levels of shame and guilt, more affectively negative views of relationships, greater use of maladaptive and self‐sacrificing defenses, and more impaired reality testing. These findings offer some preliminary empirical support for the validity of psychodynamic theories of suicidal behavior. Depression 4:89–91 (1996). © 1997 Wiley‐Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106104/1/9_ftp.pd

    Novel translocation responses of cytosolic phospholipase A2α fluorescent proteins

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    AbstractCytosolic phospholipase A2 (cPLA2)α responds to the rise in cytosolic Ca2+ ([Ca2+]i) attending cell stimulation by moving to intracellular membranes, releasing arachidonic acid (AA) from these membranes, and thereby initiating the synthesis of various lipid mediators. Under some conditions, however, cPLA2α translocation occurs without any corresponding changes in [Ca2+]i. The signal for such responses has not been identified. Using confocal microscopy to track fluorescent proteins fused to cPLA2α or cPLA2α's C2 domain, we find that AA mimics Ca2+ ionophores in stimulating cPLA2α translocations to the perinuclear ER and to a novel site, the lipid body. Unlike the ionophores, AA acted independently of [Ca2+]i rises and did not translocate the proteins to the Golgi. AA's action did not involve its metabolism to eicosanoids or acylation into cellular lipids. Receptor agonists also stimulated translocations targeting lipid bodies. We propose that AA is a signal for Ca2+-independent cPLA2α translocation and that lipid bodies are common targets of cPLA2α and contributors to stimulus-induced lipid mediator synthesis

    Impact of dialect use on a basic component of learning to read

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    Can some black-white differences in reading achievement be traced to differences in language background? Many African American children speak a dialect that differs from the mainstream dialect emphasized in school. We examined how use of alternative dialects affects decoding, an important component of early reading and marker of reading development. Behavioral data show that use of the alternative pronunciations of words in different dialects affects reading aloud in developing readers, with larger effects for children who use more African American English. Mechanisms underlying this effect were explored with a computational model, investigating factors affecting reading acquisition. The results indicate that the achievement gap may be due in part to differences in task complexity: children whose home and school dialects differ are at greater risk for reading difficulties because tasks such as learning to decode are more complex for them

    Low Mass Printable Devices for Energy Capture, Storage, and Use

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    The energy-efficient, environmentally friendly technology that will be presented is the result of a Space Act Agreement between NthDegree Technologies Worldwide, Inc., and the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC). The work combines semiconductor and printing technologies to advance lightweight electronic and photonic devices having excellent potential for commercial and exploration applications. Device development involves three projects that relate to energy generation and consumption: (1) a low-mass efficient (low power, low heat emission) micro light-emitting diode (LED) area lighting device; (2) a low-mass omni-directional efficient photovoltaic (PV) device with significantly improved energy capture; and (3) a new approach to building super-capacitors. These three technologies, energy capture, storage, and usage (e.g., lighting), represent a systematic approach for building efficient local micro-grids that are commercially feasible; furthermore, these same technologies, appropriately replacing lighting with lightweight power generation, will be useful for enabling inner planetary missions using smaller launch vehicles and to facilitate surface operations during lunar and planetary surface missions. The PV device model is a two sphere, light trapped sheet approximately 2-mm thick. The model suggests a significant improvement over current thin film systems. For lighting applications, all three technology components are printable in-line by printing sequential layers on a standard screen or flexographic direct impact press using the three-dimensional printing technique (3DFM) patented by NthDegree. One primary contribution to this work in the near term by the MSFC is to test the robustness of prototype devices in the harsh environments that prevail in space and on the lunar surface. It is anticipated that this composite device, of which the lighting component has passed off-gassing testing, will function appropriately in such environments consistent with NASA s exploration missions. Advanced technologies such as this show promise for both space flight and terrestrial applications
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