41 research outputs found
The role of cytokine gene polymorphisms in the pathogenesis of abdominal aortic aneurysms: A case-control study
AbstractBackground: Cytokines are the primary mediators of inflammation and also influence matrix metalloproteinase expression, both of which are important in development of abdominal aortic aneurysm (AAA). A significant, but as yet unknown, familial factor contributes to the pathogenesis of AAA. Many cytokine genes contain polymorphic sites, some of which affect cytokine production in vitro. Cytokine gene polymorphisms may therefore influence the pathogenesis of AAA. The purpose of this study was to determine whether there is any association between cytokine gene polymorphisms and AAA. Methods and Results: This case-control study comprised 100 patients with AAA and 100 age-matched and sex-matched control subjects. For each case and control subject in the study, genotypes at the following cytokine gene polymorphic loci were determined: interleukin (IL)-1ÎČ +3953, IL-6 â174, IL-10 â1082, IL-10 â592, and tumor necrosis factors-α â308. Allele and genotype frequencies were compared between AAA and control groups, and odds ratios (OR) were calculated for the presence of AAA with each allele at each locus examined as risk factors. The IL-10 â1082 A allele was significantly more common in the AAA group than the control group (P =.03). The OR for the IL-10 â1082 A allele as a risk factor for AAA was 1.8 (95% confidence interval, 0.9-3.6). Discussion: These associations suggest a significant role for IL-10 in the pathogenesis of AAA. This association of AAA with the IL-10 â1082 A allele is also biologically plausible; the IL-10 â1082 A allele is associated with low IL-10 secretion, and it may be that AAA develops in patients who are unable to mount the same anti-inflammatory response as those who do not have AAA. (J Vasc Surg 2003;37:999-1005.
Physics research on the TCV tokamak facility: from conventional to alternative scenarios and beyond
The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the deviceâs unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly non-inductive H-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power âstarvationâ reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached L-mode phase, increasing the outer connection length reduces the inâout heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variable-configuration baffles and possibly divertor pumping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECRH and 1 MW neutral beam injection heating will be added
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A study of hydrocarbon migration events: Development and application of new methods for constraining the time of migration and an assessment of rock-fluid interactions. Final report, September 1, 1991--August 31, 1994
The authors are conducting the research to test and refine a paleomagnetic method for dating hydrocarbon migration, and to assess the chemical alteration of crude oils resulting from fluid-rock interactions. Samples were collected for paleomagnetic and organic geochemical investigations from several units. These include the Old Red Sandstone in Scotland, and the Schoolhouse Member of the Maroon Formation and the Belden Formation in Colorado. Studies of these units are completed or underway. In addition, simulation experiments, where the authors are attempting to form magnetite in the laboratory, are underway
Response of Northern Bobwhite Movements to Management-Driven Disturbance in a Shrub-Dominated Ecosystem
Despite inhabiting fire-adapted grasslands and shrublands across much of their continental distribution, northern bobwhite (Colinus virginianus, hereafter bobwhite) behavior relative to disturbance (e.g., fire) is poorly understood, especially in the western fringe of their distribution. We assessed bobwhite movement and space use following dormant season burning (January-March 2013-2014) in a sand shinnery oak (Quercus havardii, hereafter shinnery oak) plant community. We captured and radio-marked bobwhites (n=369) and monitored them via radiotelemetry across burn treatments (averaging 254 ha) ranging from 0 to 12, 13 to 24, 25 to 36, and >36 months post fire (hereafter, time since fire [TSF]) at the Packsaddle Wildlife Management Area in western Oklahoma, United States. Mean covey home range size was 76.6 ha ± 5.9 [SE] (range; 12-270 ha) (n = 61 coveys), which is substantially larger than covey home ranges reported for other regions. Prescribed fire affected space use of coveys (F4, 54 = 2.95, P 36 TSF (78.9 ha [± 6.54]). Generalized linear mixed models demonstrated that neither spring dispersal (movements or area traversed) were correlated with TSF, age, or sex (n = 114), further demonstrating aminimal effect of prescribed fire; however, dispersal areas were greater in 2013 than in 2014 (P < 0.05). Our research shows that prescribed fire applied at a landscape scale had limited effects on short-term bobwhite movement and space use. These findings also suggest that in shinnery oak vegetation communities land managers can use prescribed fire across large spatial extents without substantially altering the space use or movement of bobwhites. © 2016 The Society for Range Management.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
Magnetic susceptibility of early Paleozoic and Precambrian paleosols
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148637/1/Retallack_et_al_2003_Palaeo-3-magnetic_susceptibility_of_Precambrian_and_Paleozoic_paleosols.pd
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A hierarchical perspective to woody plant encroachment for conservation of prairie-chickens
Encroachment of Great Plains grasslands by fire-sensitive woody plants is a large-scale, regional process that fragments grassland landscapes. Using prairie grouse (Tympanuchus spp.) of conservation concern,we apply hierarchy theory to demonstrate how regional processes constrain lower-level processes and reduce the success of local management. For example, fire and grazingmanagementmay be locally important to conservation, but the application of fire and grazing disturbances rarely cause irreversible fragmentation of grasslands in the Great Plains. These disturbance processes cause short-term alterations in vegetation conditions that can be positive or negative, but from a long-term perspective fire maintains large tracts of continuous rangelands by limiting woody plant encroachment. Conservation efforts for prairie grouse should be focused on landscape processes that contribute to landscape fragmentation, such as increased dominance of trees or conversion to other land uses. In fact, reliance on localmanagement (e.g.,maintaining vegetation structure) to alter prairie grouse vital rates is less important to grouse population persistence given contemporary landscape level changes. Changing grass height, litter depth, or increasing the cover of forbs may impact a fewremaining prairie-chickens, but itwill not create useable space at a scale relevant to the historic conditions that existed before land conversion and fire suppression.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
A hierarchical perspective to woody plant encroachment for conservation of prairie-chickens
Encroachment of Great Plains grasslands by fire-sensitive woody plants is a large-scale, regional process that fragments grassland landscapes. Using prairie grouse (Tympanuchus spp.) of conservation concern,we apply hierarchy theory to demonstrate how regional processes constrain lower-level processes and reduce the success of local management. For example, fire and grazingmanagementmay be locally important to conservation, but the application of fire and grazing disturbances rarely cause irreversible fragmentation of grasslands in the Great Plains. These disturbance processes cause short-term alterations in vegetation conditions that can be positive or negative, but from a long-term perspective fire maintains large tracts of continuous rangelands by limiting woody plant encroachment. Conservation efforts for prairie grouse should be focused on landscape processes that contribute to landscape fragmentation, such as increased dominance of trees or conversion to other land uses. In fact, reliance on localmanagement (e.g.,maintaining vegetation structure) to alter prairie grouse vital rates is less important to grouse population persistence given contemporary landscape level changes. Changing grass height, litter depth, or increasing the cover of forbs may impact a fewremaining prairie-chickens, but itwill not create useable space at a scale relevant to the historic conditions that existed before land conversion and fire suppression.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information