285 research outputs found

    Nighttime air quality under desert conditions

    Get PDF
    Nighttime concentrations of the gas phase nitrate radical (NO3) were successfully measured during a four week field campaign in an arid urban location, Reno Nevada, using long-path Differential Optical Absorbance Spectrometry (DOAS). While typical concentrations of NO3 ranged from 5 to 20ppt, elevated concentrations were observed during a wildfire event. Horizontal mixing in the free troposphere was considerable because the sampling site was above the stable nocturnal boundary layer every night and this justified a box modeling approach. Process analysis of box model simulations showed NO3 accounted for approximately half of the loss of internal olefins, 60% of the isoprene loss, and 85% of the α-pinene loss during the nighttime hours during a typical night of the field study. The NO3+aldehyde reactions were not as important as anticipated. On a polluted night impacted by wildfires upwind of the sampling location, NO3 reactions were more important. Model simulations overpredicted NO2 concentrations for both case studies and inorganic chemistry was the biggest influence on NO3 concentrations and on nitric acid formation. The overprediction may be due to additional NO2 loss processes that were not included in the box model, as deposition and N2O5 uptake had no significant effect on NO2 levels

    The HLA class II allele DRB1*1501 is over-represented in patients with idiopathic pulmonary fibrosis

    Get PDF
    Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and medically refractory lung disease with a grim prognosis. Although the etiology of IPF remains perplexing, abnormal adaptive immune responses are evident in many afflicted patients. We hypothesized that perturbations of human leukocyte antigen (HLA) allele frequencies, which are often seen among patients with immunologic diseases, may also be present in IPF patients. Methods/Principal Findings: HLA alleles were determined in subpopulations of IPF and normal subjects using molecular typing methods. HLA-DRB1*15 was over-represented in a discovery cohort of 79 Caucasian IPF subjects who had lung transplantations at the University of Pittsburgh (36.7%) compared to normal reference populations. These findings were prospectively replicated in a validation cohort of 196 additional IPF subjects from four other U.S. medical centers that included both ambulatory patients and lung transplantation recipients. High-resolution typing was used to further define specific HLA-DRB1*15 alleles. DRB1*1501 prevalence in IPF subjects was similar among the 143 ambulatory patients and 132 transplant recipients (31.5% and 34.8%, respectively, p = 0.55). The aggregate prevalence of DRB1*1501 in IPF patients was significantly greater than among 285 healthy controls (33.1% vs. 20.0%, respectively, OR 2.0; 95%CI 1.3-2.9, p = 0.0004). IPF patients with DRB1*1501 (n = 91) tended to have decreased diffusing capacities for carbon monoxide (DLCO) compared to the 184 disease subjects who lacked this allele (37.8±1.7% vs. 42.8±1.4%, p = 0.036). Conclusions/Significance: DRB1*1501 is more prevalent among IPF patients than normal subjects, and may be associated with greater impairment of gas exchange. These data are novel evidence that immunogenetic processes can play a role in the susceptibility to and/or manifestations of IPF. Findings here of a disease association at the HLA-DR locus have broad pathogenic implications, illustrate a specific chromosomal area for incremental, targeted genomic study, and may identify a distinct clinical phenotype among patients with this enigmatic, morbid lung disease

    The Mych Gene Is Required for Neural Crest Survival during Zebrafish Development

    Get PDF
    Background: Amomg Myc family genes, c-Myc is known to have a role in neural crest specification in Xenopus and in craniofacial development in the mouse. There is no information on the function of other Myc genes in neural crest development, or about any developmental role: of zebrafish Myc genes. Principal Findings: We isolated the zebrafish mych (myc homologue) gene. Knockdown of mych leads to sever defects in craniofacial development and in certain other tissues including the eye. These phenotypes appear to be caused by cell death in the neural crest and in the eye field in the anterior brain. Significance: Mych is a novel factor required for neural crest cell survival in zebrafish

    X-ray emission from the Sombrero galaxy: discrete sources

    Get PDF
    We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    Get PDF
    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Stable Vascular Connections and Remodeling Require Full Expression of VE-Cadherin in Zebrafish Embryos

    Get PDF
    BACKGROUND: VE-cadherin is an endothelial specific, transmembrane protein, that clusters at adherens junctions where it promotes homotypic cell-cell adhesion. VE-cadherin null mutation in the mouse results in early fetal lethality due to altered vascular development. However, the mechanism of action of VE-cadherin is complex and, in the mouse embryo, it is difficult to define the specific steps of vascular development in which this protein is involved. METHODOLOGY AND PRINCIPAL FINDINGS: In order to study the role VE-cadherin in the development of the vascular system in a more suitable model, we knocked down the expression of the coding gene in zebrafish. The novel findings reported here are: 1) partial reduction of VE-cadherin expression using low doses of morpholinos causes vascular fragility, head hemorrhages and increase in permeability; this has not been described before and suggests that the total amount of the protein expressed is an important determinant of vascular stability; 2) concentrations of morpholinos which abrogate VE-cadherin expression prevent vessels to establish successful reciprocal contacts and, as a consequence, vascular sprouting activity is not inhibited. This likely explains the observed vascular hyper-sprouting and the presence of several small, collapsing vessels; 3) the common cardinal vein lacks a correct connection with the endocardium leaving the heart separated from the rest of the circulatory system. The lack of closure of the circulatory loop has never been described before and may explain some downstream defects of the phenotype such as the lack of a correct vascular remodeling. CONCLUSIONS AND SIGNIFICANCE: Our observations identify several steps of vascular development in which VE-cadherin plays an essential role. While it does not appear to regulate vascular patterning it is implicated in vascular connection and inhibition of sprouting activity. These processes require stable cell-cell junctions which are defective in absence of VE-cadherin. Notably, also partial modifications in VE-cadherin expression prevent the formation of a stable vasculature. This suggests that partial internalization or change of function of this protein may strongly affect vascular stability and organization

    Constraints on parton distribution functions and extraction of the strong coupling constant from the inclusive jet cross section in pp collisions at √s=7 TeV

    Get PDF
    Peer reviewe

    Measurement of prompt J/ψ pair production in pp collisions at √s = 7 Tev

    Get PDF
    Peer reviewe
    corecore