5,435 research outputs found

    Coos county teens’ family relationships

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    This fact sheet examines Coos County, New Hampshire teens’ perceptions of their family relationship experiences using data from the Coos Youth Study collected in 2011 from 418 eleventh graders in all Coos County public schools. Authors Corinna Jenkins Tucker and Desiree Wiesen-Martin report that Coos older adolescents feel close to their parents and siblings but also argue with them. A small group of youths report perpetrating violence on a family member

    Systolic and diastolic ventricular function in zebrafish embryos: Influence of norepenephrine, MS-222 and temperature

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    <p>Abstract</p> <p>Background</p> <p>Zebrafish are increasingly used to study the influences of gene mutation and manipulation on cardiac development, structure and function. In this study, a video edge detection system was used to characterise, continuously, cardiac ventricle function in 2–5 days old zebrafish embryos embedded in 0.6% agar and examined under light microscopy at room temperature (22°C). Using video edge detection software (IonOptix Inc), the motion of a small region of the cardiac ventricle wall was converted to a continuous chart trace allowing analysis of wall motion amplitude (WMA) and myocardial wall velocity during systole (MWVs) and diastole (MWVd).</p> <p>Results</p> <p>Cardiac wall motion characteristics changed progressively from day 2 to 5 (WMA, 2-days, 17.6 ± 4.4 μm vs 5-days, 24.6 ± 4.7 μm, p < 0.01). MWVd was more rapid than MWVs at all developmental time points. Embryonic hearts were also assessed after increasing concentrations of norepenephrine (NE) and the anaesthetic agent MS222 (tricaine) were added to the bathing water. In response to NE, WMA increased significantly more in 4 day embryos compared with 2 day embryos (change in WMA,13.6 ± 8.2 μm vs 4.0 ± 8.8 μm, p = 0.01, respectively) while the decrease in WMA in response to MS222 was similar in both 2 and 4-day embryos. Heart rate, MWVs and MWVd were significantly higher at 28°C compared with 22°C. No differences in cardiac function were observed between AB and Golden strains.</p> <p>Conclusion</p> <p>Video edge detection appears sufficiently sensitive to detect subtle changes in diastolic and systolic cardiac function during development and changes resulting from pharmacological and environmental interventions. Such measurements could be valuable in assessment of altered cardiac function after genetic manipulation.</p

    Diffuse Galactic antimatter from faint thermonuclear supernovae in old stellar populations

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    Our Galaxy hosts the annihilation of a few ×1043\times 10^{43} low-energy positrons every second. Radioactive isotopes capable of supplying such positrons are synthesised in stars, stellar remnants, and supernovae. For decades, however, there has been no positive identification of a main stellar positron source leading to suggestions that many positrons originate from exotic sources like the Galaxy's central super-massive black hole or dark matter annihilation. %, but such sources would not explain the recently-detected positron signal from the extended Galactic disk. Here we show that a single type of transient source, deriving from stellar populations of age 3-6 Gyr and yielding ~0.03 M⊙M_\odot of the positron emitter 44^{44}Ti, can simultaneously explain the strength and morphology of the Galactic positron annihilation signal and the solar system abundance of the 44^{44}Ti decay product 44^{44}Ca. This transient is likely the merger of two low-mass white dwarfs, observed in external galaxies as the sub-luminous, thermonuclear supernova known as SN1991bg-like.Comment: 28 pages main text with 4 figures in preprint style; 26 pages of Supplementary Informatio

    Modified Light Use Efficiency Model for Assessment of Carbon Sequestration in Grasslands of Kazakhstan: Combining Ground Biomass Data and Remote-sensing

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    A modified light use efficiency (LUE) model was tested in the grasslands of central Kazakhstan in terms of its ability to characterize spatial patterns and interannual dynamics of net primary production (NPP) at a regional scale. In this model, the LUE of the grassland biome (n) was simulated from ground-based NPP measurements, absorbed photosynthetically active radiation (APAR) and meteorological observations using a new empirical approach. Using coarse-resolution satellite data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly NPP was calculated from 1998 to 2008 over a large grassland region in Kazakhstan. The modelling results were verified against scaled up plot-level observations of grassland biomass and another available NPP data set derived from a field study in a similar grassland biome. The results indicated the reliability of productivity estimates produced by the model for regional monitoring of grassland NPP. The method for simulation of n suggested in this study can be used in grassland regions where no carbon flux measurements are accessible

    90GHz and 150GHz observations of the Orion M42 region. A sub-millimeter to radio analysis

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    We have used the new 90GHz MUSTANG camera on the Robert C. Byrd Green Bank Telescope (GBT) to map the bright Huygens region of the star-forming region M42 with a resolution of 9" and a sensitivity of 2.8mJy/beam. 90GHz is an interesting transition frequency, as MUSTANG detects both the free-free emission characteristic of the HII region created by the Trapezium stars, normally seen at lower frequencies, and thermal dust emission from the background OMC1 molecular cloud, normally mapped at higher frequencies. We also present similar data from the 150GHz GISMO camera taken on the IRAM telescope. This map has 15" resolution. By combining the MUSTANG data with 1.4, 8, and 21GHz radio data from the VLA and GBT, we derive a new estimate of the emission measure (EM) averaged electron temperature of Te = 11376K by an original method relating free-free emission intensities at optically thin and optically thick frequencies. Combining ISO-LWS data with our data, we derive a new estimate of the dust temperature and spectral emissivity index within the 80" ISO-LWS beam toward OrionKL/BN, Td = 42K and Beta=1.3. We show that both Td and Beta decrease when going from the HII region and excited OMC1 interface to the denser UV shielded part of OMC1 (OrionKL/BN, Orion S). With a model consisting of only free-free and thermal dust emission we are able to fit data taken at frequencies from 1.5GHz to 854GHz.Comment: 18 pages, 8 figures, submitted to the Astrophysical Journa

    SANEPIC: A Map-Making Method for Timestream Data From Large Arrays

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    We describe a map-making method which we have developed for the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) experiment, but which should have general application to data from other submillimeter arrays. Our method uses a Maximum Likelihood based approach, with several approximations, which allows images to be constructed using large amounts of data with fairly modest computer memory and processing requirements. This new approach, Signal And Noise Estimation Procedure Including Correlations (SANEPIC), builds upon several previous methods, but focuses specifically on the regime where there is a large number of detectors sampling the same map of the sky, and explicitly allowing for the the possibility of strong correlations between the detector timestreams. We provide real and simulated examples of how well this method performs compared with more simplistic map-makers based on filtering. We discuss two separate implementations of SANEPIC: a brute-force approach, in which the inverse pixel-pixel covariance matrix is computed; and an iterative approach, which is much more efficient for large maps. SANEPIC has been successfully used to produce maps using data from the 2005 BLAST flight.Comment: 27 Pages, 15 figures; Submitted to the Astrophysical Journal; related results available at http://blastexperiment.info/ [the BLAST Webpage

    A Bright Submillimeter Source in the Bullet Cluster (1E0657--56) Field Detected with BLAST

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    We present the 250, 350, and 500 micron detection of bright submillimeter emission in the direction of the Bullet Cluster measured by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). The 500 micron centroid is coincident with an AzTEC 1.1 mm point-source detection at a position close to the peak lensing magnification produced by the cluster. However, the 250 micron and 350 micron centroids are elongated and shifted toward the south with a differential shift between bands that cannot be explained by pointing uncertainties. We therefore conclude that the BLAST detection is likely contaminated by emission from foreground galaxies associated with the Bullet Cluster. The submillimeter redshift estimate based on 250-1100 micron photometry at the position of the AzTEC source is z_phot = 2.9 (+0.6 -0.3), consistent with the infrared color redshift estimation of the most likely IRAC counterpart. These flux densities indicate an apparent far-infrared luminosity of L_FIR = 2E13 Lsun. When the amplification due to the gravitational lensing of the cluster is removed, the intrinsic far-infrared luminosity of the source is found to be L_FIR <= 10^12 Lsun, consistent with typical luminous infrared galaxies.Comment: Accepted for publication in the Astrophysical Journal. Maps are available at http://blastexperiment.info

    Over half of the far-infrared background light comes from galaxies at z >= 1.2

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    Submillimetre surveys during the past decade have discovered a population of luminous, high-redshift, dusty starburst galaxies. In the redshift range 1 <= z <= 4, these massive submillimetre galaxies go through a phase characterized by optically obscured star formation at rates several hundred times that in the local Universe. Half of the starlight from this highly energetic process is absorbed and thermally re-radiated by clouds of dust at temperatures near 30 K with spectral energy distributions peaking at 100 microns in the rest frame. At 1 <= z <= 4, the peak is redshifted to wavelengths between 200 and 500 microns. The cumulative effect of these galaxies is to yield extragalactic optical and far-infrared backgrounds with approximately equal energy densities. Since the initial detection of the far-infrared background (FIRB), higher-resolution experiments have sought to decompose this integrated radiation into the contributions from individual galaxies. Here we report the results of an extragalactic survey at 250, 350 and 500 microns. Combining our results at 500 microns with those at 24 microns, we determine that all of the FIRB comes from individual galaxies, with galaxies at z >= 1.2 accounting for 70 per cent of it. As expected, at the longest wavelengths the signal is dominated by ultraluminous galaxies at z > 1.Comment: Accepted to Nature. Maps available at http://blastexperiment.info
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