We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading ...effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha, and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.
Background Exercise-induced bronchoconstriction (EIB) is a prototypical feature of indirect airway hyperresponsiveness. Mast cells are implicated in EIB, but the characteristics, regulation, and ...function of mast cells in patients with EIB are poorly understood. Objectives We sought to examine mast cell infiltration of the airway epithelium in patients with EIB and the regulation of mast cell phenotype and function by epithelially derived cytokines. Methods Endobronchial biopsy specimens, epithelial brushings, and induced sputum were obtained from asthmatic patients with and without EIB and healthy control subjects. Mast cell proteases were quantified by using quantitative PCR, and mast cell density was quantified by using design-based stereology. Airway epithelial responses to wounding and osmotic stress were assessed in primary airway epithelial cells and ex vivo murine lung tissue. Mast cell granule development and function were examined in cord blood–derived mast cells. Results Tryptase and carboxypeptidase A3 expression in epithelial brushings and epithelial mast cell density were selectively increased in the asthma group with EIB. An in vitro scratch wound initiated the release of thymic stromal lymphopoietin, which was greater in epithelial cells derived from asthmatic patients. Osmotic stress induced the release of IL-33 from explanted murine lungs, which was increased in allergen-treated mice. Thymic stromal lymphopoietin combined with IL-33 increased tryptase and carboxypeptidase A3 immunostaining in mast cell precursors and selectively increased cysteinyl leukotriene formation by mast cells in a manner that was independent of in vitro sensitization. Conclusions Mast cell infiltration of the epithelium is a critical determinant of indirect airway hyperresponsiveness, and the airway epithelium might serve as an important regulator of the development and function of this mast cell population.
Population stratification refers to differences in allele frequencies between cases and controls due to systematic differences in ancestry rather than association of genes with disease. It has been ...proposed that false positive associations due to stratification can be controlled by genotyping a few dozen unlinked genetic markers. To assess stratification empirically, we analyzed data from 11 case-control and case-cohort association studies. We did not detect statistically significant evidence for stratification but did observe that assessments based on a few dozen markers lack power to rule out moderate levels of stratification that could cause false positive associations in studies designed to detect modest genetic risk factors. After increasing the number of markers and samples in a case-cohort study (the design most immune to stratification), we found that stratification was in fact present. Our results suggest that modest amounts of stratification can exist even in well designed studies.
Background:Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from ...biomass fuel in Malawian homes.Methods:Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire.Results:Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m3 (206 μg/m3). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m3 for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes.Conclusions:Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health.
The OLYMPUS experiment Milner, R.; Hasell, D.K.; Kohl, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2014, Letnik:
741
Journal Article
Recenzirano
Odprti dostop
The OLYMPUS experiment was designed to measure the ratio between the positron–proton and electron–proton elastic scattering cross-sections, with the goal of determining the contribution of two-photon ...exchange to the elastic cross-section. Two-photon exchange might resolve the discrepancy between measurements of the proton form factor ratio, μpGEp/GMp, made using polarization techniques and those made in unpolarized experiments. OLYMPUS operated on the DORIS storage ring at DESY, alternating between 2.01GeV electron and positron beams incident on an internal hydrogen gas target. The experiment used a toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight detectors to measure rates for elastic scattering over the polar angular range of approximately 25°–75°. Symmetric Møller/Bhabha calorimeters at 1.29° and telescopes of GEM and MWPC detectors at 12° served as luminosity monitors. A total luminosity of approximately 4.5fb−1 was collected over two running periods in 2012. This paper provides details on the accelerator, target, detectors, and operation of the experiment.
ABSTRACT Optical microlensing surveys are restricted from detecting events near the Galactic plane and center, where the event rate is thought to be the highest due to the high optical extinction of ...these fields. In the near-infrared (NIR), however, the lower extinction leads to a corresponding increase in event detections and is a primary driver for the wavelength coverage of the WFIRST microlensing survey. During the 2015 and 2016 bulge observing seasons, we conducted NIR microlensing surveys with UKIRT in conjunction with and in support of the Spitzer and Kepler microlensing campaigns. Here, we report on five highly extinguished ( ), low-Galactic latitude ( ) microlensing events discovered from our 2016 survey. Four of them were monitored with an hourly cadence by optical surveys but were not reported as discoveries, likely due to the high extinction. Our UKIRT surveys and suggested future NIR surveys enable the first measurement of the microlensing event rate in the NIR. This wavelength regime overlaps with the bandpass of the filter in which the WFIRST microlensing survey will conduct its highest-cadence observations, making this event rate derivation critically important for optimizing its yield.
We present high time resolution global imaging of a sunward propagating giant undulation event from start to finish. The event occurred on 24 November 2001 during a very disturbed storm interval. The ...giant undulations began to develop at around 1345 UTC and persisted for approximately 2 h. The sunward propagation speed was on the order of 0.6 km/s (relative to magnetic latitude–magnetic local time coordinate system). The undulations had a wavelength of ∼718 km and amplitudes of ∼890 km and produced ULF pulsations on the ground with a period of ∼1108 s. We show (1) that the undulations were associated with subauroral polarization stream (SAPS) flows that were caused by the proton plasma sheet penetrating substantially farther earthward than the electron plasma sheet on the duskside and (2) that they may have been related to the arrival on the duskside of a substorm‐associated westward traveling surge‐like structure. The observations appear to be consistent with the development of a shear flow and/or ballooning type of instability at the plasmapause driven by intense SAPS‐associated shear flows.
Sawtooth events have been identified at geosynchronous orbit as large‐amplitude quasiperiodic (2–4 hour period) modulations of the energetic electron and ion fluxes. They are called sawtooth events ...because the shape of the flux versus time profiles are composed of rapid increases followed by gradual decreases that resemble the teeth on a saw blade. Although much of the phenomenology associated with sawtooth events is substorm‐like, there is still debate as to whether the individual teeth are substorms or not. Here we examine each of the teeth associated with the 10–11 August 2000 sawtooth event in detail. We find that all but one of the teeth were associated with injections at geosynchronous orbit and that most of the teeth were consistent with the hypothesis that they are predominantly caused by unusually large and longitudinally extended substorms. A few were unclear or complex, and the final flux enhancement at 1845:36 UT was not a substorm but a solar wind shock‐associated disturbance. In addition, the presence of numerous dispersionless flux perturbations in the LANL SOPA data provides support for the hypothesis that solar wind pressure variations can modulate the flux profiles to some extent. For the substorm events we find that the geosynchronous particle injections were neither globally simultaneous nor globally dispersionless but were instead consistent with a nightside/duskside source in most cases. Similarly, we show that the field dipolarizations were also not global and simultaneous. Each of the substorms was also associated with high‐latitude negative H bays, middle‐ and low‐latitude positive H bays, a partial recovery in Sym‐H, and the onset of Pi2 ULF pulsations. In addition, we show that the auroral distribution develops in a systematic way during each cycle of a sawtooth substorm event. Specifically, a localized auroral onset develops on the lower branch of a thinned double‐oval distribution. The location of onset is typically premidnight and often occurs to the west of intense omega band forms. This is followed by westward, eastward, and poleward expansion and the copious production of auroral streamers which can develop in complex patterns including a “spoke‐like” morphology. The double‐oval configuration thins again during the stretching phase until the next onset occurs and the cycle repeats. A schematic representation of the auroral dynamics associated with sawtooth substorms is also presented.
Background The health status and health needs of adults with intellectual disability (ID) change with advancing age, and are often accompanied by difficulties with vision, hearing, mobility, stamina ...and some mental processes.
Aim The present study collected health status information on a large cohort of adults with ID aged ≥ 40 years living in small group, community‐based residences in two representative areas of New York State, USA.
Method Adult group home residents with ID aged between 40 and 79 years (n = 1371) were surveyed to determine their health status and patterns of morbidity.
Results Most subjects were characterized as being in good health. The frequency of cardiovascular, musculoskeletal and respiratory conditions, and sensory impairments increased with age, while neurological, endocrine and dermatological diseases did not. Psychiatric and behavioural disorders declined with increasing age, at least through 70 years of age. Although most conditions increased with age, their frequency varied by sex and level of ID. Frequencies of age‐related organ system morbidity were compared to data from the National Health and Nutrition Evaluation Survey III. It was found that adults with ID had a lower overall reported frequency of cardiovascular risk factors, including hypertension and hyperlipidaemia, and adult‐onset diabetes. Inconsistencies with mortality data among older adults with ID were observed (which showed equal if not greater prevalence of deaths as a result of cardiovascular disease and cancer).
Conclusion These results suggest that either a cohort effect is operating (i.e. contemporary populations are healthier than previous populations), or that there may be under‐recognition of select risk factors and diseases.
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