18,938 research outputs found

    Ichthyoplankton Adjacent to Live-Bottom Habitats in Onslow Bay, North Carolina

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    The abundance and distribution of ichthyoplankton adjacent to live-bottom habitats (rock outcroppings containing rich, sessile invertebrate communities and many species of tropical and subtropical fishes) in open-shelf waters « 55-m isobath) in Onslow Bay, North Carolina, were investigated. Larvae of reef-associated genera, especially the economically important subtropical and tropical members of the families Haemulidae (Haemulon), Lutjanidae (Lutjanus and Rltomboplites), Serranidae (Mycteroperca and Epinephelus), and Sparidae (Calamus and Pagrus) were targeted. Larvae representing 40 families were collected in neuston tows. Commonly collected reef-associated families were Balistidae, Blenniidae (dominated by the reef-associated Parablennius marmoreus) , Mullidae, and Gobiidae. Larvae representing 70 families were collected in subsurface tows. Reef-associated families commonly collected included Apogonidae, Balistidae, Gobiidae, Haemulidae, LutJanidae, Scaridae, and Serranidae. Larval Haemulon sp (p)., Lutjanus sp(p)., and Rltomboplites aurorubens were commonly collected and thus it is likely that these taxa spawn in Onslow Bay and recruit to live-bottom sites within the area. Other families of fishes commonly collected but generally not considered reef-associated included Bothidae, Callionymidae, Carangidae, Clupeidae, Engraulidae, and Ophidiidae. Estuarine-dependent species (e.g. the clupeid Brevoortia tyrannus and the sciaenids Leiostomus xanthurus and Micropogonias undulatus) were an important component of the ichthyoplankton during late fall and winter. The frequent occurrence of larvae from oceanic species (e.g. gonostomatids and myctophids) indicated that Gulf Stream waters had intruded onto the shelf, transporting these larvae to open-shelf waters off North Carolina.(PDF file containes 36 pages.

    Attitude control system for sounding rockets Patent

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    Development of attitude control system for sounding rocket stabilization during ballistic phase of fligh

    Partitions with fixed differences between largest and smallest parts

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    We study the number p(n,t)p(n,t) of partitions of nn with difference tt between largest and smallest parts. Our main result is an explicit formula for the generating function Pt(q):=n1p(n,t)qnP_t(q) := \sum_{n \ge 1} p(n,t) \, q^n. Somewhat surprisingly, Pt(q)P_t(q) is a rational function for t>1t>1; equivalently, p(n,t)p(n,t) is a quasipolynomial in nn for fixed t>1t>1. Our result generalizes to partitions with an arbitrary number of specified distances.Comment: 5 page

    What Students Tell Us About School If We Ask

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    This article examines what school climate factors students perceive as helping them be successful in school, and what school administrators can do to aid the process. Specifically, the questions that drove this inquiry were How does sociocultural theory impact student voice and student engagement in the classroom? How does caring pedagogy impact student voice and student engagement in the classroom? What school climate factors do students perceive as helping them to be successful in school

    Fiber optic microphone having a pressure sensing reflective membrane and a voltage source for calibration purpose

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    A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a back plate for damping membrane motion. The back plate further provides a means for on-line calibration of the microphone

    NASA-JSC ozone observations for validation of Nimbus 7-LIMS data

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    A series of balloon flights undertaken to validate data received from the limb infrared monitor of the stratorphere instrument aboard the Nimbus 7 satellite is discussed. Ozone data profiles, which included altitude, pressure, and mixing ratio, obtained during both ascent and descent of the balloons are reported. The measurement concept, instrumental uncertainties, and temporal variations observed for several time periods are discussed

    BUILD -- A System Construction Tool

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    BUILD is a proposed tool for constructing systems from existing modules. BUILD system descriptions are composed of module declarations and assertions of how modules refer to each other. An extensible library of information about module types and module interaction types is maintained. The library contains information that allows BUILD to derive construction dependencies from the module declarations and referencing patterns enumerated in system descriptions. BUILD will support facilities not adequately provided by existing tools; including automatic derivation of system descriptions, patching of systems, and incorporation of information about how modules change (e.g. the ability to differentiate between the effect of adding a function definition and the effect of adding a comment).MIT Artificial Intelligence Laborator

    Intersexual conflict influences female reproductive success in a female-dispersing primate

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    In group-living mammals, individual efforts to maximize reproductive success result in conflicts and compromises between the sexes. Females utilize counterstrategies to minimize the costs of sexual coercion by males, but few studies have examined the effect of such behaviors on female reproductive success. Secondary dispersal by females is rare among group-living mammals, but in western gorillas, it is believed to be a mate choice strategy to minimize infanticide risk and infant mortality. Previous research suggested that females choose males that are good protectors. However, how much female reproductive success varies depending on male competitive ability and whether female secondary dispersal leads to reproductive costs or benefits has not been examined. We used data on 100 females and 229 infants in 36 breeding groups from a 20-year long-term study of wild western lowland gorillas to investigate whether male tenure duration and female transfer rate had an effect on interbirth interval, female birth rates, and offspring mortality. We found that offspring mortality was higher near the end of males’ tenures, even after excluding potential infanticide when those males died, suggesting that females suffer a reproductive cost by being with males nearing the end of their tenures. Females experience a delay in breeding when they dispersed, having a notable effect on birth rates of surviving offspring per female if females transfer multiple times in their lives. This study exemplifies that female counterstrategies to mitigate the effects of male-male competition and sexual coercion may not be sufficient to overcome the negative consequences of male behavior

    Geometric analysis of optical frequency conversion and its control in quadratic nonlinear media

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    We analyze frequency conversion and its control among three light waves using a geometric approach that enables the dynamics of the waves to be visualized on a closed surface in three dimensions. It extends the analysis based on the undepleted-pump linearization and provides a simple way to understand the fully nonlinear dynamics. The Poincaré sphere has been used in the same way to visualize polarization dynamics. A geometric understanding of control strategies that enhance energy transfer among interacting waves is introduced, and the quasi-phase-matching strategy that uses microstructured quadratic materials is illustrated in this setting for both type I and II second-harmonic generation and for parametric three-wave interactions

    High temperature fiber optic microphone having a pressure-sensing reflective membrane under tensile stress

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    A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a backplate for damping membrane motion. The backplate further provides a means for on-line calibration of the microphone
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