395 research outputs found

    Association of West Nile virus illness and urban landscapes in Chicago and Detroit

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    BACKGROUND: West Nile virus infection in humans in urban areas of the Midwestern United States has exhibited strong spatial clustering during epidemic years. We derived urban landscape classes from the physical and socio-economic factors hypothesized to be associated with West Nile Virus (WNV) transmission and compared those to human cases of illness in 2002 in Chicago and Detroit. The objectives were to improve understanding of human exposure to virus-infected mosquitoes in the urban context, and to assess the degree to which environmental factors found to be important in Chicago were also found in Detroit. RESULTS: Five urban classes that partitioned the urban space were developed for each city region. The classes had many similarities in the two settings. In both regions, the WNV case rate was considerably higher in the urban class associated with the Inner Suburbs, where 1940–1960 era housing dominates, vegetation cover is moderate, and population density is moderate. The land cover mapping approach played an important role in the successful and consistent classification of the urban areas. CONCLUSION: The analysis demonstrates how urban form and past land use decisions can influence transmission of a vector-borne virus. In addition, the results are helpful to develop hypotheses regarding urban landscape features and WNV transmission, they provide a structured method to stratify the urban areas to locate representative field study sites specifically for WNV, and this analysis contributes to the question of how the urban environment affects human health

    Quantifying Methane Emissions in the Uintah Basin During Wintertime Stagnation Episodes

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    This study presents a meteorologically-based methodology for quantifying basin-scale methane (CH4) emissions in Utah’s Uintah Basin, which is home to over 9,000 active and producing oil and natural gas wells. Previous studies in oil and gas producing regions have often relied on intensive aircraft campaigns to estimate methane emissions. However, the high cost of airborne campaigns prevents their frequent undertaking, thus providing only daytime snapshots of emissions rather than more temporally-representative estimates over multiple days. Providing estimates of CH4 emissions from oil and natural gas production regions across the United States is important to inform leakage rates and emission mitigation efforts in order to curb the potential impacts of these emissions on global climate change and local air quality assessments. Here we introduce the Basin-constrained Emissions Estimate (BEE) method, which utilizes the confining topography of a basin and known depth of a pollution layer during multi-day wintertime cold-air pool episodes to relate point observations of CH4 to basin-scale CH4 emission rates. This study utilizes ground-based CH4 observations from three fixed sites to calculate daily increases in CH4, a laser ceilometer to estimate pollution layer depth, and a Lagrangian transport model to assess the spatial representativity of surface observations. BEE was applied to two cold-air pool episodes during the winter of 2015–2016 and yielded CH4 emission estimates between 44.60 +/– 9.66 × 103 and 61.82 +/– 19.76 × 103 kg CH4 hr–1, which are similar to the estimates proposed by previous studies performed in the Uintah Basin. The techniques used in this study could potentially be utilized in other deep basins worldwide

    Eddy covariance flux measurements of pollutant gases in urban Mexico City

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    Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 [CO subscript 2] from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 [CO subscript 2] and olefins were measured by the conventional EC technique using an open path CO2 [CO subscript 2] sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes [C subscript 2 - benzenes] were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 [CO subscript 2] and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The data show that the emissions inventory is in reasonable agreement with measured olefin and CO2 [CO subscript 2] fluxes, while C2-benzenes [C subscript 2 - benzenes] and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not present in the mobile emissions inventory.National Science Foundation (U.S.) (Grant ATM-0528227)United States. Dept. of Energy (Award DE-FG02-05ER63980)Mexico. Comisión Ambiental MetropolitanaMolina Center for Energy and the Environmen

    Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

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    To better understand how forest management, phenology, vegetation type, and actual and simulated climatic change affect seasonal and inter‐annual variations in soil respiration (Rs), we analyzed more than 100,000 individual measurements of soil respiration from 23 studies conducted over 22 years at the Harvard Forest in Petersham, Massachusetts, USA. We also used 24 site‐years of eddy‐covariance measurements from two Harvard Forest sites to examine the relationship between soil and ecosystem respiration (Re). Rs was highly variable at all spatial (respiration collar to forest stand) and temporal (minutes to years) scales of measurement. The response of Rs to experimental manipulations mimicking aspects of global change or aimed at partitioning Rs into component fluxes ranged from −70% to +52%. The response appears to arise from variations in substrate availability induced by changes in the size of soil C pools and of belowground C fluxes or in environmental conditions. In some cases (e.g., logging, warming), the effect of experimental manipulations on Rs was transient, but in other cases the time series were not long enough to rule out long‐term changes in respiration rates. Inter‐annual variations in weather and phenology induced variation among annual Rs estimates of a magnitude similar to that of other drivers of global change (i.e., invasive insects, forest management practices, N deposition). At both eddy‐covariance sites, aboveground respiration dominated Re early in the growing season, whereas belowground respiration dominated later. Unusual aboveground respiration patterns—high apparent rates of respiration during winter and very low rates in mid‐to‐late summer—at the Environmental Measurement Site suggest either bias in Rs and Re estimates caused by differences in the spatial scale of processes influencing fluxes, or that additional research on the hard‐to‐measure fluxes (e.g., wintertime Rs, unaccounted losses of CO2 from eddy covariance sites), daytime and nighttime canopy respiration and its impacts on estimates of Re, and independent measurements of flux partitioning (e.g., aboveground plant respiration, isotopic partitioning) may yield insight into the unusually high and low fluxes. Overall, however, this data‐rich analysis identifies important seasonal and experimental variations in Rs and Re and in the partitioning of Re above‐ vs. belowground

    Uniqueness Typing for Resource Management in Message-Passing Concurrency

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    We view channels as the main form of resources in a message-passing programming paradigm. These channels need to be carefully managed in settings where resources are scarce. To study this problem, we extend the pi-calculus with primitives for channel allocation and deallocation and allow channels to be reused to communicate values of different types. Inevitably, the added expressiveness increases the possibilities for runtime errors. We define a substructural type system which combines uniqueness typing and affine typing to reject these ill-behaved programs

    Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

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    To better understand how forest management, phenology, vegetation type, and actual and simulated climatic change affect seasonal and inter‐annual variations in soil respiration (Rs), we analyzed more than 100,000 individual measurements of soil respiration from 23 studies conducted over 22 years at the Harvard Forest in Petersham, Massachusetts, USA. We also used 24 site‐years of eddy‐covariance measurements from two Harvard Forest sites to examine the relationship between soil and ecosystem respiration (Re). Rs was highly variable at all spatial (respiration collar to forest stand) and temporal (minutes to years) scales of measurement. The response of Rs to experimental manipulations mimicking aspects of global change or aimed at partitioning Rs into component fluxes ranged from −70% to +52%. The response appears to arise from variations in substrate availability induced by changes in the size of soil C pools and of belowground C fluxes or in environmental conditions. In some cases (e.g., logging, warming), the effect of experimental manipulations on Rs was transient, but in other cases the time series were not long enough to rule out long‐term changes in respiration rates. Inter‐annual variations in weather and phenology induced variation among annual Rs estimates of a magnitude similar to that of other drivers of global change (i.e., invasive insects, forest management practices, N deposition). At both eddy‐covariance sites, aboveground respiration dominated Re early in the growing season, whereas belowground respiration dominated later. Unusual aboveground respiration patterns—high apparent rates of respiration during winter and very low rates in mid‐to‐late summer—at the Environmental Measurement Site suggest either bias in Rs and Re estimates caused by differences in the spatial scale of processes influencing fluxes, or that additional research on the hard‐to‐measure fluxes (e.g., wintertime Rs, unaccounted losses of CO2 from eddy covariance sites), daytime and nighttime canopy respiration and its impacts on estimates of Re, and independent measurements of flux partitioning (e.g., aboveground plant respiration, isotopic partitioning) may yield insight into the unusually high and low fluxes. Overall, however, this data‐rich analysis identifies important seasonal and experimental variations in Rs and Re and in the partitioning of Re above‐ vs. belowground

    Identification of ocular cicatricial pemphigoid antibody binding site(s

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    PURPOSE. To identify specific site(s) on human ␤4 molecule to which sera from ocular cicatricial pemphigoid (OCP) patients bind and to determine its role in the process of blister formation. METHODS. Clone the fragments representing the extracellular and intracellular domain of ␤4 molecule from normal human conjunctival mRNA into an expression vector; map the region to which sera from OCP patients bind by Western blot analysis. Determine the role of the immunodominant region in pathogenesis by demonstrating the ability of the rabbit antibody to the immunodominant region to produce separation of basement membrane zone (BMZ) from the basal epithelial layer when incubated with normal human conjunctiva in an in vitro organ culture model. RESULTS. Majority of the OCP sera tested bound to the Cterminal end of the intracellular domain (IC3.0) of the human ␤4 integrin. Further subcloning of IC3.0 demonstrated that a smaller fragment extending from 1489 aa to 1572 aa (IC3.4) was responsible for this binding. This region may have multiple antibody binding sites. Antibody to human IC3.0 and IC3.4 produced in rabbit, resulted in BMZ separation, histologically identical with that observed when normal human conjunctiva was cultured with OCP sera in an human conjunctival organ culture model. CONCLUSIONS. These observations identify IC3.4 as the antibody binding site for sera of OCP patients and suggest a possible role for it in blister formation. Indirectly it highlights certain important aspects of the structural and functional dynamics of the biology of the hemidesmosomes and basement membranes. (Invest Ophthalmol Vis Sci. 2001;42:379 -385) M ucous membrane pemphigoid (MMP) is a multisystemic autoimmune inflammatory disease that affects mucous membrane derived from stratified squamous epithelium including the conjunctiva and occasionally the skin. 1,2 In some patients, the involvement of the conjunctiva is more prominent than other mucous membranes. Such a subset of MMP patients are referred to as having ocular cicatricial pemphigoid (OCP). Progressive subepithelial fibrosis follows the chronic conjunctivitis, resulting in severe dryness of the eye, ocular keratinization, and blindness secondary to corneal scarring. Sera of patients with subepithelial blistering diseases have demonstrable levels of circulating antibodies that bind to different antigens within the basement membrane zone (BMZ) of skin and mucosa. 10 There are several human autoimmune diseases in which the target autoantigens are identified as being intracellular in location. MATERIALS AND METHODS Sera The method section confirms adherence to the Declaration of Helsinki. Sera used in this study were obtained from 20 patients with active mucous membrane pemphigoid before beginning of systemic treatment. These patients had the pemphigoid disease process involving multiple mucosa but not the skin. Ocular involvement was the most prominent symptom, resulting in blindness in many of these patients. The clinical diagnosis of OCP was established by routine histology and confirmed by direct immunofluorescence of the conjunctiva. The presence of IgG and or complement was detected in the conjunctival BMZ. Sera of these OCP patients binds to the epidermal side of the salt split skin. Control sera were obtained from 20 healthy individuals, 5 patients each with confirmed bullous pemphigoid (BP) and pemphigus vulgaris (PV). Blood samples were collected after informed consent, and the study was approved by the institutional review board

    Lymphocytic Choriomeningitis in Michigan

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    We summarize the first reported case of acquired lymphocytic choriomeningitis virus (LCMV) infection in Michigan to be investigated by public health authorities and provide evidence of the focal nature of LCMV infection in domestic rodents. Results of serologic and virologic testing in rodents contrasted, and negative serologic test results should be confirmed by tissue testing
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