3,063 research outputs found

    ISOPHOT Observations of Narrow-Line Seyfert 1 Galaxies

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    Broad infrared spectra (7-200 micrometer) of four NLS1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on board the Infrared Space Observatory (ISO), are presented. The infrared luminosities and temperatures, opacities and sizes of the emitting dust components are derived. A comparison between the observed infrared spectra and the optical emission line fluxes of a sample of 16 NLS1 galaxies suggests that these objects suffer different degrees of dust absorption according to the inclination of the line of sight with respect to the dust distribution.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

    The Geography of Non-formal Manifolds

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    We show that there exist non-formal compact oriented manifolds of dimension nn and with first Betti number b1=b0b_1=b\geq 0 if and only if n3n\geq 3 and b2b\geq 2, or n(72b)n\geq (7-2b) and 0b20\leq b\leq 2. Moreover, we present explicit examples for each one of these cases.Comment: 8 pages, one reference update

    Maturation of the Calico Scallop, Argopecten gibbus, Determined by Ovarian Color Changes

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    Ovarian color was described for the calico scallop, Argopecten gibbus, by sizes and seasons from May 1970 to October 1971 on the Cape Canaveral grounds, Florida. Seven stages of ovarian development were recognized primarily by color and sequence of development and graded from immature to ripe to spent. Scallops as small as 20 mm shell height can be ripe. There were distinct changes in developmental stage by season. Most scallops were ripe from January to May; in August, large scallops were spent or developing and small scallops were immature. Based on seasonal occurrence of ripe and partially spawned scallops, spawning extended primarily from about November to July and was intense from January to May. There was no spawning in August. Variations occurred in the spawning pattern between years

    Uniform semiclassical wave function for coherent 2D electron flow

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    We find a uniform semiclassical (SC) wave function describing coherent branched flow through a two-dimensional electron gas (2DEG), a phenomenon recently discovered by direct imaging of the current using scanned probed microscopy. The formation of branches has been explained by classical arguments, but the SC simulations necessary to account for the coherence are made difficult by the proliferation of catastrophes in the phase space. In this paper, expansion in terms of "replacement manifolds" is used to find a uniform SC wave function for a cusp singularity. The method is then generalized and applied to calculate uniform wave functions for a quantum-map model of coherent flow through a 2DEG. Finally, the quantum-map approximation is dropped and the method is shown to work for a continuous-time model as well.Comment: 9 pages, 7 figure

    Ask the Experts: Campus Event Planning

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    Muon spin relaxation study of the magnetism in unilluminated Prussian Blue analogue photomagnets

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    We present longitudinal field muon spin relaxation (μ\muSR) measurements in the unilluminated state of the photo-sensitive molecular magnetic Co-Fe Prussian blue analogues M12x_{1-2x}Co1+x_{1+x}[Fe(CN)6_6]z\cdot z H2_2O, where M=K and Rb with x=0.4x=0.4 and 0.17\simeq 0.17, respectively. These results are compared to those obtained in the x=0.5x=0.5 stoichiometric limit, Co1.5_{1.5}[Fe(CN)6_6]6\cdot 6 H2_2O, which is not photo-sensitive. We find evidence for correlation between the range of magnetic ordering and the value of xx in the unilluminated state which can be explained using a site percolation model.Comment: 7 pages, 12 figure

    Effects of Methylene Blue and Polyethelene Glycol on Facial Nerve Axotomy Recovery

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    poster abstractInjury and disease are common factors affecting peripheral nerves and can lead to loss of function. Recovery time after an injury is slow and not very efficient in humans. Treatment methods involving methylene blue (MB) and polyethylene glycol (PEG) have shown combinational effects in sciatic nerve axotomies. We are using behavior analysis of eye blink reflex and vibrissae orientation and movement as a measurement of rate of functional recovery. We will have treatment groups of both cut and crush rats. For each group we will be testing the effect of PEG/MB or no treatment control groups. The results of these treatment groups are significant to finding treatment options for clinical use

    Comparison of multiple approaches to calculate time-varying biological reference points in climate-linked population-dynamics models

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    Fisheries managers use biological reference points (BRPs) as targets or limits on fishing and biomass to maintain productive levels of fish stock biomass. There are multiple ways to calculate BRPs when biological parameters are time varying. Using summer flounder (Paralichthys dentatus) as a case study, we investigated time-varying approaches in concert with climate-linked population models to understand the impact of environmentally driven variability in natural mortality, recruitment, and size-At-Age on two commonly used BRPs [B0(t) and F35%(t)]. We used the following two approaches to calculate time-varying BRPs: dynamic-BRP and moving-Average-BRP. We quantified the variability and uncertainty of different climate dependencies and estimation approaches, attributed BRP variation to variation in life-history processes, and evaluated how using different approaches impacts estimates of stock status. Results indicate that the dynamic-BRP approach using the climate-linked natural mortality model produced the least variable reference points compared to others calculated. Summer flounder stock status depended on the estimation approach and climate model used. These results emphasize that understanding climate dependencies is important for summer flounder reference points and perhaps other species, and careful consideration is warranted when considering what time-varying approach to use, ideally based upon simulation studies within a proposed set of management procedures
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