7,430 research outputs found

    Absorption and Screening in Phycomyces

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    In vivo absorption measurements were made through the photosensitive zones of Phycomyces sporangiophores and absorption spectra are presented for various growth media and for wavelengths between 400 and 580 m”. As in mycelia, ß-carotene was the major pigment ordinarily found. The addition of diphenylamine to the growth media caused a decrease in ß-carotene and an increase in certain other carotenoids. Growth in the dark substantially reduced the amount of ß-carotene in the photosensitive zone; however, growth on a lactate medium failed to suppress ß-carotene in the growing zone although the mycelia appeared almost colorless. Also when diphenylamine was added to the medium the absorption in the growing zone at 460 m” was not diminished although the colored carotenoids in the bulk of the sporangiophore were drastically reduced. Absorption which is characteristic of the action spectra was not found. Sporangiophores immersed in fluids with a critical refractive index show neither positive nor negative tropism. Measurements were made of the critical refractive indices for light at 495 and 510 m”. The critical indices differed only slightly. Assuming primary photoreceptors at the cell wall, the change in screening due to absorption appears too large to be counterbalanced solely by a simple effect of the focusing change. The possibility is therefore advanced that the receptors are internal to most of the cytoplasm; i.e., near the vacuole

    Simultaneous Identification of the Diffusion Coefficient and the Potential for the Schr\"odinger Operator with only one Observation

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    This article is devoted to prove a stability result for two independent coefficients for a Schr\"odinger operator in an unbounded strip. The result is obtained with only one observation on an unbounded subset of the boundary and the data of the solution at a fixed time on the whole domain

    LABEL USE AND IMPORTANCE RANKINGS FOR SELECTED MILK LABELING ATTRIBUTES

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    Results from a random telephone survey of households in 13 southern states suggest that 80 percent of respondents use labels when making food purchasing decisions. Label users are more likely to be college-educated, female, living in the East South Central Region, and to be childless or to have children between the ages of five and twelve. Age is invariant to label use; however, older respondents are more likely to assign higher importance ratings to caloric, fat, sodium, and cholesterol content than to price, expiration date, and brand when buying fresh-fluid milk.Agribusiness,

    Decoherence under many-body system-environment interactions: a stroboscopic representation based on a fictitiously homogenized interaction rate

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    An environment interacting with portions of a system leads to multiexponential interaction rates. Within the Keldysh formalism, we fictitiously homogenize the system-environment interaction yielding a uniform decay rate facilitating the evaluation of the propagators. Through an injection procedure we neutralize the fictitious interactions. This technique justifies a stroboscopic representation of the system-environment interaction which is useful for numerical implementation and converges to the natural continuous process. We apply this procedure to a fermionic two-level system and use the Jordan-Wigner transformation to solve a two-spin swapping gate in the presence of a spin environment.Comment: 11 pages, 3 figures, title changed, some typos change

    Toward Collaboration and Community in Student-Faculty Relationships

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    Central to support services for deaf and hard-of-hearing college students is the creation of processes through which deaf students and hearing faculty recognize and respect each other’s cultural values. This article describes how conversations from a focus group of deaf students and conversations from a focus group of hearing faculty reflect cross-cultural relatedness and community within a traditional liberal arts university. Higgins’ (1980) conceptualization of interdependence and Palmer’s (1987) notions of relatedness and community served as the framework by which the conversations were analyzed. Communicating in class, using interpreters and notetakers, and establishing identity in the academic community emerged as themes that shaped both students’ and faculty members’ perceptions of deafness. The individual and group insights constructed a collaborative community within the larger context of the academy

    The ρ\rho Meson Light-Cone Distribution Amplitudes of Leading Twist Revisited

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    We give a complete re-analysis of the leading twist quark-antiquark light-cone distribution amplitudes of longitudinal and transverse ρ\rho mesons. We derive Wandzura-Wilczek type relations between different distributions and update the coefficients in their conformal expansion using QCD sum rules including next-to-leading order radiative corrections. We find that the distribution amplitudes of quarks inside longitudinally and transversely polarized ρ\rho mesons have a similar shape, which is in contradiction to previous analyses.Comment: 21 pages, latex2e, requires a4wide.sty and epsf.sty, 6 PS figures include

    High Energy Neutrinos from Cosmic Ray Interactions in Clusters of Galaxies

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    The spatial clustering of galaxies in galaxy clusters implies that the background of infrared (IR) light in the intracluster medium (ICM) may exceed the universal background. Cosmic rays injected within the ICM propagate diffusively and at low enough energies are trapped there for cosmological times. The photopion production interactions of cosmic rays with the IR photons are responsible for the generation of neutrinos whose detection may shed some light on the origin and propagation of high energy cosmic rays in the universe. Here we discuss our calculations of the flux of neutrinos from single clusters as well as the contribution of photopion production in clusters of galaxies to the diffuse neutrino background.Comment: 10 pages, 10 figures, submitted to PR

    K*(892)0 Production in Relativistic Heavy Ion Collisions at sqrt(s_NN) = 130 GeV

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    Preliminary results on the K*(892)0 -> pi + K production using the mixed-event technique are presented. The measurements are performed at mid-rapidity by the STAR detector in sqrt(s_NN) = 130 GeV Au-Au collisions at RHIC. The K*0 to negative hadron, kaon and phi ratios are obtained and compared to the measurements in e+e-, pp and pbarp at various energies.Comment: 8 pages, 3 figures, proceedings of Strange Quarks in Matter (SQM2001), Frankfurt am Main, Germany, to be published in J. Phys.

    An annotated list of the Lepidoptera of Honduras

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    A biodiversity inventory of the Lepidoptera of Pico Bonito National Park and vicinity, in the Department of Atlantida of northern Honduras, was initiated in 2009 to obtain baseline data. We present a revised checklist of Honduran butterfly species (updated from the initial 1967 lists), as well as the first comprehensive list of Honduran moths. Our updated list includes 550 species of Papilionoidea, 311 Hesperioidea, and 1,441 moth species
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