536 research outputs found

    Characterization and manipulation of fruit susceptibility to \u3ci\u3eDrosophila suzukii\u3c/i\u3e

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    Drosophila suzukii (Matsumura) is an economic pest of small fruits and cherries that attacks intact ripening fruits. Host susceptibility may be influenced by characteristics such as flesh firmness, penetration force of the skin, total soluble solids (TSS, also known as Brix), and pH. Improved knowledge of factors affecting fruit susceptibility is needed for developing thresholds and risk prediction models for IPM. A combination of laboratory and field studies was conducted to develop prediction and potential management tools. First, a direct bioassay was used to calculate the probability of oviposition in a given fruit based on various characteristics as determined across laboratory and field trials in Oregon and North Carolina, US. When multiple characteristics were evaluated simultaneously, oviposition probability consistently increased as penetration force decreased and pH increased. Oviposition probability sometimes increased as TSS increased. Second, raspberries and blueberries in unsprayed fields had substantially lower infestation in ripening fruit compared to ripe fruit. There was no or minimal infestation in green fruit. Third, given that skin penetration force influences oviposition, practices used to improve fruit quality were examined in laboratory no-choice cages for potential reduction of oviposition. Blueberry fruit sprayed with calcium silicate in the field had greater penetration force and firmness and reduced number of eggs laid by D. suzukii compared to untreated fruit. Other calcium-based treatments increased Ca content and firmness of fruit relative to untreated fruit. Timing of insecticide spray for D. suzukii might be delayed until fruit become susceptible

    Nuclear transparency and effective kaon-nucleon cross section from the A(e, e'K+) reaction

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    We have determined the transparency of the nuclear medium to kaons from A(e,e′K+)A(e,e^{'} K^{+}) measurements on 12^{12}C, 63^{63}Cu, and 197^{197}Au targets. The measurements were performed at the Jefferson Laboratory and span a range in four-momentum-transfer squared Q2^2=1.1 -- 3.0 GeV2^2. The nuclear transparency was defined as the ratio of measured kaon electroproduction cross sections with respect to deuterium, (σA/σD\sigma^{A}/\sigma^{D}). We further extracted the atomic number (AA) dependence of the transparency as parametrized by T=(A/2)α−1T= (A/2)^{\alpha-1} and, within a simple model assumption, the in-medium effective kaon-nucleon cross sections. The effective cross sections extracted from the electroproduction data are found to be smaller than the free cross sections determined from kaon-nucleon scattering experiments, and the parameter α\alpha was found to be significantly larger than those obtained from kaon-nucleus scattering. We have included similar comparisons between pion- and proton-nucleon effective cross sections as determined from electron scattering experiments, and pion-nucleus and proton-nucleus scattering data.Comment: 7 pages, 5 figure

    Validation of Diffuse Correlation Spectroscopic Measurement of Cerebral Blood Flow Using Phase-Encoded Velocity Mapping Magnetic Resonance Imaging

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    Diffuse correlation spectroscopy (DCS) is a novel optical technique that appears to be an excellent tool for assessing cerebral blood flow in a continuous and non-invasive manner at the bedside. We present new clinical validation of the DCS methodology by demonstrating strong agreement between DCS indices of relative cerebral blood flow and indices based on phase-encoded velocity mapping magnetic resonance imaging (VENC MRI) of relative blood flow in the jugular veins and superior vena cava. Data were acquired from 46 children with single ventricle cardiac lesions during a hypercapnia intervention. Significant increases in cerebral blood flow, measured both by DCS and by VENC MRI, as well as significant increases in oxyhemoglobin concentration, and total hemoglobin concentration, were observed during hypercapnia. Comparison of blood flow changes measured by VENC MRI in the jugular veins and by DCS revealed a strong linear relationship, R = 0.88, p \u3c 0.001, slope = 0.91 ± 0.07. Similar correlations were observed between DCS and VENC MRI in the superior vena cava, R = 0.77, slope = 0.99 ± 0.12, p \u3c 0.001. The relationship between VENC MRI in the aorta and DCS, a negative control, was weakly correlated, R = 0.46, slope = 1.77 ± 0.45, p \u3c 0.001

    Measurement of Nuclear Transparency for the A(e,e' pi^+) Reaction

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    We have measured the nuclear transparency of the A(e,e' pi^+) process in ^{2}H,^{12}C, ^{27}Al, ^{63}Cu and ^{197}Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q^2 = 1.1 - 4.7 (GeV/c)^2. The nuclear transparency was extracted as the super-ratio of (σA/σH)(\sigma_A/\sigma_H) from data to a model of pion-electroproduction from nuclei without pi-N final state interactions. The Q^2 and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations, and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.Comment: 5 pages, 3 figs Changes to figure 2 and 3 (error band updated and theory curves updated

    Scaling study of the pion electroproduction cross sections and the pion form factor

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    The 1^{1}H(e,e′π+e,e^\prime \pi^+)n cross section was measured for a range of four-momentum transfer up to Q2Q^2=3.91 GeV2^2 at values of the invariant mass, WW, above the resonance region. The Q2Q^2-dependence of the longitudinal component is consistent with the Q2Q^2-scaling prediction for hard exclusive processes. This suggests that perturbative QCD concepts are applicable at rather low values of Q2Q^2. Pion form factor results, while consistent with the Q2Q^2-scaling prediction, are inconsistent in magnitude with perturbative QCD calculations. The extraction of Generalized Parton Distributions from hard exclusive processes assumes the dominance of the longitudinal term. However, transverse contributions to the cross section are still significant at Q2Q^2=3.91 GeV2^2.Comment: 6 pages, 3 figure

    Study of the A(e,e'Ï€+\pi^+) Reaction on 1^1H, 2^2H, 12^{12}C, 27^{27}Al, 63^{63}Cu and 197^{197}Au

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    Cross sections for the p(e,e′π+e,e'\pi^{+})n process on 1^1H, 2^2H, 12^{12}C, 27^{27}Al, 63^{63}Cu and 197^{197}Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the nuclear transparencies. Data were taken for four-momentum transfers ranging from Q2Q^2=1.1 to 4.8 GeV2^2 for a fixed center of mass energy of WW=2.14 GeV. The ratio of σL\sigma_L and σT\sigma_T was extracted from the measured cross sections for 1^1H, 2^2H, 12^{12}C and 63^{63}Cu targets at Q2Q^2 = 2.15 and 4.0 GeV2^2 allowing for additional studies of the reaction mechanism. The experimental setup and the analysis of the data are described in detail including systematic studies needed to obtain the results. The results for the nuclear transparency and the differential cross sections as a function of the pion momentum at the different values of Q2Q^2 are presented. Global features of the data are discussed and the data are compared with the results of model calculations for the p(e,e′π+e,e'\pi^{+})n reaction from nuclear targets.Comment: 28 pages, 19 figures, submited to PR

    Scaling of the F_2 structure function in nuclei and quark distributions at x>1

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    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1x>1, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie

    Impact of socioeconomic deprivation on rate and cause of death in severe mental illness

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    Background: Socioeconomic status has important associations with disease-specific mortality in the general population. Although individuals with Severe Mental Illnesses (SMI) experience significant premature mortality, the relationship between socioeconomic status and mortality in this group remains under investigated.<p></p> Aims: To assess the impact of socioeconomic status on rate and cause of death in individuals with SMI (schizophrenia and bipolar disorder) relative to the local (Glasgow) and wider (Scottish) populations.<p></p> Methods: Cause and age of death during 2006-2010 inclusive for individuals with schizophrenia or bipolar disorder registered on the Glasgow Psychosis Clinical Information System (PsyCIS) were obtained by linkage to the Scottish General Register Office (GRO). Rate and cause of death by socioeconomic status, measured by Scottish Index of Multiple Deprivation (SIMD), were compared to the Glasgow and Scottish populations.<p></p> Results: Death rates were higher in people with SMI across all socioeconomic quintiles compared to the Glasgow and Scottish populations, and persisted when suicide was excluded. Differences were largest in the most deprived quintile (794.6 per 10,000 population vs. 274.7 and 252.4 for Glasgow and Scotland respectively). Cause of death varied by socioeconomic status. For those living in the most deprived quintile, higher drug-related deaths occurred in those with SMI compared to local Glasgow and wider Scottish population rates (12.3% vs. 5.9%, p = <0.001 and 5.1% p = 0.002 respectively). A lower proportion of deaths due to cancer in those with SMI living in the most deprived quintile were also observed, relative to the local Glasgow and wider Scottish populations (12.3% vs. 25.1% p = 0.013 and 26.3% p = <0.001). The proportion of suicides was significantly higher in those with SMI living in the more affluent quintiles relative to Glasgow and Scotland (54.6% vs. 5.8%, p = <0.001 and 5.5%, p = <0.001). Discussion and conclusions: Excess mortality in those with SMI occurred across all socioeconomic quintiles compared to the Glasgow and Scottish populations but was most marked in the most deprived quintiles when suicide was excluded as a cause of death. Further work assessing the impact of socioeconomic status on specific causes of premature mortality in SMI is needed
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