6,308 research outputs found

    Phenotypic Expression in the Paper Wasp \u3ci\u3ePolistes Fuscatus\u3c/i\u3e (Hymenoptera: Vespidae)

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    Quantification of color/color pattern in Polistes fuscatus (Fabricius) revealed that these attributes were the interaction of two antagonistic color sequences; their expression being highly correlated with nest microclimate (relative humidity-temperature). Color/ color pattern expressions were modified under experimental conditions to produce forms having natural counterparts in the field. Principal coordinates analyses and trend surface analyses using specimens collected throughout the United States indicated three color pattern trends, representing three distinct geographic areas, and, when objectively defined, without intergradation between and/or among areas. It was concluded that fuscatus should not be considered a widespread, polytypic species; rather, as three discrete species: an eastern, P. fuscatus (Fabricius); a western, P. aurifer Saussure; and an undescribed yellow form from the southwestern United States

    Trichoptera (Caddisflies) of Watercress Marsh, Columbiana County, Ohio

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    Author Institution: Department of Biological Sciences, Youngstown State University ; Biology Department, Thiel CollegeCaddisfly adults numbering 4,371 were collected by means of light traps at Watercress Marsh, Columbiana Co., Ohio, from June 1976 to October 1981. The marsh occupies a site of the Grand River lobe of the Wisconsin Glacier near its southernmost extent in Columbiana Co. The 69 species in the 10 families collected included 15 species of Limnephilidae and 4 new state records. Seasonal species diversity values were calculated

    Positive allosteric modulators of the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor

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    L-glutamate is the major excitatory neurotransmitter in the mammalian central nervous system (CNS) and plays a fundamental role in the control of motor function, cognition and mood. The physiological effects of glutamate are mediated through two functionally distinct receptor families. While activation of metabotropic (G-protein coupled) glutamate receptors results in modulation of neuronal excitability and transmission, the ionotropic glutamate receptors (ligand-gated ion channels) are responsible for mediating the fast synaptic response to extracellular glutamate

    The Second International Symposium on Tilapia in Aquaculture

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    Proceedings of the symposium held in 1987 in Bangkok, Thailand, by tilapia scientists to discuss strategies for future research and development in the tilapia industry worldwide. Contains 82 full papers, 17 poster abstracts and author and species indexes. The full papers were presented under 7 sessions: culture systems, management and production; pathology; genetics and reproduction; nutrition, physiology; biology and ecology; and economics and socioeconomics.Tilapia culture, Conferences

    Spin-Dependent Tunneling of Single Electrons into an Empty Quantum Dot

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    Using real-time charge sensing and gate pulsing techniques we measure the ratio of the rates for tunneling into the excited and ground spin states of a single-electron AlGaAs/GaAs quantum dot in a parallel magnetic field. We find that the ratio decreases with increasing magnetic field until tunneling into the excited spin state is completely suppressed. However, we find that by adjusting the voltages on the surface gates to change the orbital configuration of the dot we can restore tunneling into the excited spin state and that the ratio reaches a maximum when the dot is symmetric.Comment: 4 pages, 3 figure

    Electrical control of spin relaxation in a quantum dot

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    We demonstrate electrical control of the spin relaxation time T_1 between Zeeman split spin states of a single electron in a lateral quantum dot. We find that relaxation is mediated by the spin-orbit interaction, and by manipulating the orbital states of the dot using gate voltages we vary the relaxation rate W= (T_1)^-1 by over an order of magnitude. The dependence of W on orbital confinement agrees with theoretical predictions and from these data we extract the spin-orbit length. We also measure the dependence of W on magnetic field and demonstrate that spin-orbit mediated coupling to phonons is the dominant relaxation mechanism down to 1T, where T_1 exceeds 1s.Comment: 4 pages, 3 figure
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