2,227 research outputs found

    Building an active node on the Internet

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    Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (p. 63-65).by David M. Murphy.M.Eng

    Effects of negative energy balance on liver gene and protein expression during the early postpartum period and its impacts on dairy cow fertility

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    End of project reportNegative energy balance (NEB) is a severe metabolic affecting high yielding dairy cows early post partum with both concurrent and latent negative effects on cow fertility as well as on milk production and cow health. The seasonal nature of Irish dairy production necessitates high cow fertility and a compact spring calving pattern in order to maximise grass utilisation. Poor dairy cow reproductive performance currently costs the Irish cattle industry in excess of €400 million annually. High milk yields have been associated with lower reproductive efficiency, and it has been suggested that this effect is probably mediated through its effects on the energy balance of the cow during lactation. The modern high genetic merit dairy cow prioritises nutrient supply towards milk production in early lactation and this demand takes precedence over the provision of optimal conditions for reproduction. In this study we used the bovine Affymetrix 23,000 gene microarray, which contains the most comprehensive set of bovine genes to be assembled and provides a means of investigating the modifying influences of energy balance on liver gene expression. Cows in severe negative energy balance (SNEB) in early lactation showed altered hepatic gene expression in metabolic processes as well as a down regulation of the insulin-like growth factor (IGF) system, where insulin like growth factor-1 (IGF-1), growth hormone receptor variant 1A (GHR1A) and insulin-like growth factor binding protein-acid labile subunit (IGFBP-ALS) were down regulated compared to the cows in the moderate negative energy balance MNEB group, consistent with a five-fold reduction in systemic concentrations of IGF1 in the SNEB group.Cows in SNEB showed elevated expression of key genes involved in the inflammatory response such as interleukin-8 (IL-8). There was a down regulation of genes involved in cellular growth in SNEB cows and moreover a negative regulator of cellular proliferation (HGFIN) was up regulated in SNEB cows, which is likely to compromise adaptation and recovery from NEB. The puma method of analysis revealed that 417 genes were differentially regulated by EB (P<0.05), of these genes 190 were up-regulated while 227 were down-regulated, with 405 genes having known biological functions. From Ingenuity Pathway Analysis (IPA), lipid catabolism was found to be the process most affected by differences in EB status

    Lake Breezes in Southern Ontario and Their Relation to Tornado Climatology

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    Geostationary Operational Environmental Satellite (GOES) imagery is used to demonstrate the development of lake-breeze boundaries in southern Ontario under different synoptic conditions. The orientation of the gradient wind with respect to the shorelines is important in determining the location of such lines. When moderate winds (5–10 m s21) are parallel to straight sections of coastlines, cloud lines can extend well inland. In the region between Lakes Huron and Erie lake-breeze lines merge frequently, sometimes resulting in long-lasting stationary storms and attendant heavy rain and flooding. The influence of the lakes is apparent in the tornado climatology for the region: tornadoes appear to be suppressed in regions visited by lake-modified air and enhanced in regions favored by lake-breeze convergence lines. The cloud patterns in the case of a cold front interacting with merging lake-breeze boundaries are shown to be similar to those on a major tornado outbreak day. Two of the cases discussed are used as conceptual models to explain many of the features in the patterns of tornado touchdown locations. In general, it appears that the lakes suppress tornadoes in southern Ontario, compared with neighboring states and in particular in areas where southwest winds are onshore, but enhance tornado likelihood locally in areas of frequent lake-breeze activity. 1

    Megathrust Heterogeneity, Crustal Accretion, and a Topographic Embayment in the Western Nepal Himalaya : Insights From the Inversion of Thermochronological Data

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    Between 81 degrees 30MODIFIER LETTER PRIMEE and 83 degrees E, the Himalayan range's "perfect" arcuate shape is interrupted by an embayment. We hypothesize that thrust geometry and duplexing along the megathrust at midlower-crustal depths play a leading role in growth of the embayment as well the southern margin of the Tibetan plateau. To test this hypothesis, we conducted thermokinematic modeling of published thermochronologic data from the topographic and structural embayment in the western Nepal Himalaya to investigate the three-dimensional geometry and kinematics of the megathrust at midlower-crustal depths. Models that can best reproduce observed cooling ages suggest that the megathrust in the western Nepal Himalaya is best described as two ramps connected by a long flat that extends further north than in segments to the east and west. These models suggest that the high-slope zone along the embayment lies above the foreland limb of an antiformal crustal accretion zone on the megathrust with lateral and oblique ramps at midlower-crustal depths. The lateral and oblique ramps may have initiated by ca. 10 Ma. This process may have controlled along-strike variation in Himalayan-plateau growth and therefore development of the topographic embayment. Finally, we analyze geological and morphologic features and propose an evolution model in which landscape and drainage systems across the central-western Himalaya evolve in response to crustal accretion at depth and the three-dimensional geometry of the megathrust. Our work highlights the importance of crustal accretion at different depths in orogenic-wedge growth and that the midlower crustal accretion determines the location of plateau edge.Peer reviewe

    Toxoplasma gondii infection drives conversion of NK cells into ILC1-like cells

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    Innate lymphoid cells (ILCs) were originally classified based on their cytokine profiles, placing natural killer (NK) cells and ILC1s together, but recent studies support their separation into different lineages at steady-state. However, tumors may induce NK cell conversion into ILC1-like cells that are limited to the tumor microenvironment and whether this conversion occurs beyond this environment remains unknown. Here, we describ

    Disorder-specific and shared brain abnormalities during vigilance in autism and obsessive-compulsive disorder

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    Background Autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD) are often comorbid and share similarities across some cognitive phenotypes, including certain aspects of attention. However, no functional magnetic resonance imaging (fMRI) studies have compared the underlying neural mechanisms contributing to these shared phenotypes. Methods Age and IQ-matched boys between 11 and 17 years old with ASD (N=20), OCD (N=20) and healthy controls (N = 20) performed a parametrically modulated psychomotor vigilance fMRI task. Brain activation and performance were compared between adolescents with OCD, ASD and controls. Results While boys with ASD and OCD were not impaired on task performance, there was a significant group by attention load interaction in several brain regions. With increasing attention load, left inferior frontal cortex/insula as well as left inferior parietal lobe/pre/post-central gyrus were progressively less activated in OCD boys relative to the other two groups. In addition, OCD boys showed progressively increased activation with increasing attention load in rostromedial prefrontal/anterior cingulate cortex relative to ASD and control boys. Shared neurofunctional abnormalities between ASD and OCD boys included increased activation with increasing attention load in cerebellum and occipital regions, possibly reflecting increased default mode network activation. Conclusions This first fMRI study to compare boys with ASD and OCD showed shared abnormalities in posterior cerebellar-occipital brain regions. However, OCD boys showed a disorder-specific pattern of reduced activation in left inferior frontal and temporo-parietal regions but increased activation of medial frontal regions which may potentially be related to neurobiological mechanisms underlying cognitive and clinical phenotypes of OCD
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