1,710 research outputs found

    Paragonimiasis In Iowa

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    The presence of the lung fluke, Paragonimus kelliocotti, was first recorded in the United States in a cat in 1894. It was first recognized in domesticated animals in Iowa in a dog from Blackhawk County in 1948. Subsequently, paragonimiasis has been diagnosed in dogs from Polk and Dallas counties. An additional case was found in a dog from an unrecorded county. Also, one cat from Story County has been found to harbor P. kellicotti

    Millimetre-VLBI Monitoring of AGN with Sub-milliarcsecond Resolution

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    Global millimetre VLBI allows detailed studies of the most central jet regions of AGN with unprecedent spatial resolution of a few 100-1000 Schwartzschild radii to be made. Study of these regions will help to answer the question how the highly relativistic AGN jets are launched and collimated. Since the early 1990s, bright mm-sources have been observed with global 3 mm VLBI. Here we present new images from an ongoing systematic analysis of the available observations. In particular, we focus on the structure and structural evolution of the best observed AGN jets, taking 3C 454.3 as a characteristic example. This core-dominated and highly variable quasar shows a complex morphology with individual jet components accelerating superluminally towards the outer structure. We briefly discuss the X-ray properties of 3C 454.3 and present its radio- to X-ray large-scale brightness distribution.Comment: 4 pages, 4 figures, Proceedings of the 7th EVN Symposium held in Toledo, Spain in October 2004, needs evn2004.cl

    Effects of hydrogen on the morphology and electrical properties of GaN grown by plasma-assisted molecular-beam epitaxy

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    We study the effect of introducing hydrogen gas through the rf-plasma source during plasma-assisted molecular-beam epitaxy of GaN(0001). The well-known smooth-to-rough transition that occurs for this surface as a function of decreasing Ga flux in the absence of H is found to persist even with H present, although the critical Ga flux for this transition increases. Under Ga-rich conditions, the presence of hydrogen is found to induce step bunching (facetting) on the surface. Conductive atomic force microscopy reveals that leakage current through dislocation cores is significantly reduced when hydrogen is present during the growth

    Dynamics and robustness of familiarity memory

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    When presented with an item or a face, one might have a sense of recognition without the ability to recall when or where the stimulus has been encountered before. This sense of recognition is called familiarity memory. Following previous computational studies of familiarity memory, we investigate the dynamical properties of familiarity discrimination and contrast two different familiarity discriminators: one based on the energy of the neural network and the other based on the time derivative of the energy. We show how the familiarity signal decays rapidly after stimulus presentation. For both discriminators, we calculate the capacity using mean field analysis. Compared to recall capacity (the classical associative memory in Hopfield nets), both the energy and the slope discriminators have bigger capacity, yet the energy-based discriminator has a higher capacity than one based on its time derivative. Finally, both discriminators are found to have a different noise dependence

    Molecular Gas in the Low Metallicity, Star Forming Dwarf IC 10

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    We present a complete survey of CO 1->0 emission in the Local Group dwarf irregular IC 10. The survey, conducted with the BIMA interferometer, covers the stellar disk and a large fraction of the extended HI envelope with the sensitivity and resolution necessary to detect individual giant molecular clouds (GMCs) at the distance of IC 10 (950 kpc). We find 16 clouds with a total CO luminosity of 1 x 10^6 K km s^-1 pc^2, equivalent to 4 x 10^6 Msun of molecular gas using the Galactic CO-to-H2 conversion factor. Observations with the ARO 12m find that BIMA may resolve out as much as 50% of the CO emission, and we estimate the total CO luminosity as 2.2 x 10^6 K km s^-1 pc^2. We measure the properties of 14 GMCs from high resolution OVRO data. These clouds are very similar to Galactic GMCs in their sizes, line widths, luminosities, and CO-to-H2 conversion factors despite the low metallicity of IC 10 (Z ~ 1/5 Zsun). Comparing the BIMA survey to the atomic gas and stellar content of IC 10 we find that most of the CO emission is coincident with high surface density HI. IC 10 displays a much higher star formation rate per unit molecular (H2) or total (HI+H2) gas than most galaxies. This could be a real difference or may be an evolutionary effect - the star formation rate may have been higher in the recent past.Comment: 21 pages, 14 figures, Accepted to Ap

    The N Enrichment and Supernova Ejection of the Runaway Microquasar LS 5039

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    We present an investigation of new optical and ultraviolet spectra of the mass donor star in the massive X-ray binary LS 5039. The optical band spectral line strengths indicate that the atmosphere is N-rich and C-poor, and we classify the stellar spectrum as type ON6.5 V((f)). The N-strong and C-weak pattern is also found in the stellar wind P Cygni lines of N V 1240 and C IV 1550. We suggest that the N-enrichment may result from internal mixing if the O-star was born as a rapid rotator, or the O-star may have accreted N-rich gas prior to a common-envelope interaction with the progenitor of the supernova. We re-evaluated the orbital elements to find an orbital period of P=4.4267 +/- 0.0010 d. We compared the spectral line profiles with new non-LTE, line-blanketed model spectra, from which we derive an effective temperature T_eff = 37.5 +/- 1.7 kK, gravity log g = 4.0 +/- 0.1, and projected rotational velocity V sin i = 140 +/- 8 km/s. We fit the UV, optical, and IR flux distribution using a model spectrum and extinction law with parameters E(B-V)= 1.28 +/- 0.02 and R= 3.18 +/- 0.07. We confirm the co-variability of the observed X-ray flux and stellar wind mass loss rate derived from the H-alpha profile, which supports the wind accretion scenario for the X-ray production in LS 5039. Wind accretion models indicate that the compact companion has a mass M_X/M_sun = 1.4 +/- 0.4, consistent with its identification as a neutron star. The observed eccentricity and runaway velocity of the binary can only be reconciled if the neutron star received a modest kick velocity due to a slight asymmetry in the supernova explosion (during which >5 solar masses was ejected).Comment: 38 pages, 9 figures; 2004, ApJ, 600, Jan. 10 issue, in press Discussion revised thanks to comments from P. Podsiadlowsk

    Characterization of Protease-Activated Receptor (PAR) Ligands: Parmodulins are Reversible Allosteric Inhibitors of PAR1-Driven Calcium Mobilization in Endothelial Cells

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    Several classes of ligands for Protease-Activated Receptors (PARs) have shown impressive anti-inflammatory and cytoprotective activities, including PAR2 antagonists and the PAR1-targeting parmodulins. In order to support medicinal chemistry studies with hundreds of compounds and to perform detailed mode-of-action studies, it became important to develop a reliable PAR assay that is operational with endothelial cells, which mediate the cytoprotective effects of interest. We report a detailed protocol for an intracellular calcium mobilization assay with adherent endothelial cells in multiwell plates that was used to study a number of known and new PAR1 and PAR2 ligands, including an alkynylated version of the PAR1 antagonist RWJ-58259 that is suitable for the preparation of tagged or conjugate compounds. Using the cell line EA.hy926, it was necessary to perform media exchanges with automated liquid handling equipment in order to obtain optimal and reproducible antagonist concentration-response curves. The assay is also suitable for study of PAR2 ligands; a peptide antagonist reported by Fairlie was synthesized and found to inhibit PAR2 in a manner consistent with reports using epithelial cells. The assay was used to confirm that vorapaxar acts as an irreversible antagonist of PAR1 in endothelium, and parmodulin 2 (ML161) and the related parmodulin RR-90 were found to inhibit PAR1 reversibly, in a manner consistent with negative allosteric modulation

    The redshift distribution of dusty star forming galaxies from the SPT survey

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    We use the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 to determine spectroscopic redshifts of high-redshift dusty star-forming galaxies (DSFGs) selected by their 1.4mm continuum emission in the South Pole Telescope (SPT) survey. We present ALMA 3mm spectral scans between 84-114GHz for 15 galaxies and targeted ALMA 1mm observations for an additional eight sources. Our observations yield 30 new line detections from CO, [CI] , [NII] , H_2O and NH_3. We further present APEX [CII] and CO mid-J observations for seven sources for which only a single line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new mm/submm line and photometric data of the SPT-selected DSFGs to study their redshift distribution. The combined data yield 39 spectroscopic redshifts from molecular lines, a success rate of >85%. Our sample represents the largest data set of its kind today and has the highest spectroscopic completeness among all redshift surveys of high-z DSFGs. The median of the redshift distribution is z=3.9+/-0.4, and the highest-redshift source in our sample is at z=5.8. We discuss how the selection of our sources affects the redshift distribution, focusing on source brightness, selection wavelength, and strong gravitational lensing. We correct for the effect of gravitational lensing and find the redshift distribution for 1.4mm-selected sources with a median redshift of z=3.1+/-0.3. Comparing to redshift distributions selected at shorter wavelengths from the literature, we show that selection wavelength affects the shape of the redshift distribution

    Happiness and education: troubling students for their own contentment

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    Currently higher education strategies seem to concentrate on the expedient, developing skills that can secure employment in the world of work. Following Dreyfus and Spinosa (2003), this may have immediate advantages, but in totalising pedagogic practices it may restrict our openness to people and to our own contentment with ourselves. Valuable as this may be as a way to satisfy politico-economic policy imperatives, it strays from education as an edifying process where personal development represents, through the facing up to distress and despair, an unsettling of our developing identity and a negation of our immediate desire satisfaction. Such an unsettling is not intended to give pleasure or satisfaction in the normative way in which the imperative of happiness has been used in student satisfaction surveys or in the wider societal context that this totalisation represents (Ahmed 2010). What I propose for higher education is not a dominant priority to feed the happiness for others but a mission to personal contentment revealed through realising student potentialities to them and so recognising their limitations as part of seeking an attunement to contentment
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