2,327 research outputs found
The Deepwater Horizon Oil Spill And Gulf Of Mexico Shelf Hypoxia
The oil/water/dispersant mixture from the 2010 Deepwater Horizon oil spill was juxtaposed on the Louisiana continental shelf with the annual development of oxygen-depleted bottom waters. There was uncertainty whether the oil from the spill might worsen the extent or severity of the seasonal hypoxic area formation in 2010. The surface and bottom water hydrocarbons in May were elevated compared to in June and July, while the bottom-water dissolved oxygen concentrations were higher in May and June compared to in July. The degradation of oil in the water column or sediments was not known. The results of an empirical orthogonal functions (EOF) analysis of the progression of hypoxia development in May, June and July 2010, and an analysis of conditions in July compared to a 27-year background database, indicated no difference in oxygen concentrations for May, June or July 2010, with or without oil data included, nor any difference in July 2010 compared to other years. The analysis instead indicated that, in all years compared, the hypoxic area increased with higher river discharge, higher nitrate-N load, an easterly (westward) wind and reduced wind speed. Although the analyses did not demonstrate that the oil spill affected, or did not affect, the size of the 2010 hypoxic zone, there was evidence that the 2010 hypoxia season did not differ from the long-term record
Epistatic effects between two genes in the renin-angiotensin system and systolic blood pressure and coronary artery calcification
Using the <i>Mus musculus</i> hybrid zone to assess covariation and genetic architecture of limb bone lengths
Two subspecies of the house mouse, Mus musculus domesticus and Mus musculus musculus, meet in a narrow contact zone across Europe. Mice in the hybrid zone are highly admixed, representing the full range of mixed ancestry from the two subspecies. Given the distinct morphologies of these subspecies, these natural hybrids can be used for genomewide association mapping at sufficiently high resolution to directly infer candidate genes. We focus here on limb bone length differences, which is of special interest for understanding the evolution of developmentally correlated traits. We used 172 first-generation descendants of wild-caught mice from the hybrid zone to measure the length of stylopod (humerus/femur), zeugopod (ulna/tibia) and autopod (metacarpal/metatarsal) elements in skeletal CT scans. We find phenotypic covariation between limb elements in the hybrids similar to patterns previously described in Mus musculus domesticus inbred strains, suggesting that the hybrid genotypes do not influence the covariation pattern in a major way. Mapping was performed using 143,592 SNPs and identified several genomic regions associated with length differences in each bone. Bone length was found to be highly polygenic. None of the candidate regions include the canonical genes known to control embryonic limb development. Instead, we are able to identify candidate genes with known roles in osteoblast differentiation and bone structure determination, as well as recently evolved genes of, as yet, unknown function. © 2018 John Wiley Sons Ltd
Enhancing mediastinal mass at MR: Castleman disease
We report a case of an enhancing middle mediastinal mass imaged by MR and CT. Repeated nondiagnostic biopsies in this 25-yr-old male patient had resulted in profuse hemorrhage. Final pathological diagnosis after thoracotomy and debulking was Castleman disease. This is a rare, benign lymphoproliferative disorder of uncertain etiology. Histological varieties include the hyaline vascular type (80-90%) and the plasma cell type (10-20%). Cure is generally accomplished via surgical excision. This entity should be included in the differential diagnosis of enhancing mediastinal lesions, prompting awareness of the potential for bleeding complications following biopsy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31093/1/0000770.pd
Gitksan medicinal plants-cultural choice and efficacy
BACKGROUND: The use of plants for healing by any cultural group is integrally related to local concepts of the nature of disease, the nature of plants, and the world view of the culture. The physical and chemical properties of the plants themselves also bear on their selection by people for medicines, as does the array of plants available for people to choose from. I examine use of medicinal plants from a "biobehavioral" perspective to illuminate cultural selection of plants used for medicine by the Gitksan of northwestern British Columbia, Canada. METHODS: Consultant consensus, "intercultural consensus", independent use of the same plants by other cultural groups, and phytochemistry and bioassay results from the literature, were employed in analysis of probable empirical efficacy of plant uses. RESULTS: 70% of 37 Gitksan medicinal plants were used similarly by other cultures where direct diffusion is not known to have occurred; eleven plants, including the eight most frequently mentioned medicinal plants, also show active phytochemicals or bioassays indicating probable physiologically based therapeutic effects. CONCLUSION: Analysis of intercultural consensus revealed that the majority of cultures in the British Columbia region within the plant ranges use the same plants, or closely related species, in similar ways. The rigor of this analysis is effected by the lack of consistent data on all taxa of interest for all cultures within the region
On the Potts model partition function in an external field
We study the partition function of Potts model in an external (magnetic)
field, and its connections with the zero-field Potts model partition function.
Using a deletion-contraction formulation for the partition function Z for this
model, we show that it can be expanded in terms of the zero-field partition
function. We also show that Z can be written as a sum over the spanning trees,
and the spanning forests, of a graph G. Our results extend to Z the well-known
spanning tree expansion for the zero-field partition function that arises
though its connections with the Tutte polynomial
Metabolic Syndrome and Autoimmune Diabetes: Action LADA 3
OBJECTIVE—The purpose of this study was to estimate whether prevalence of metabolic syndrome in adult European diabetic patients is associated with type of diabetes
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How predation and landscape fragmentation affect vole population dynamics
Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable
populations. The gradient has often been attributed to changes in the interactions between microtines and their predators.
Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species,
it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding
season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating
population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in
the field. The distinction is here attempted using realistic agent-based modelling.
Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and
ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities
whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical
autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of
altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the
presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator
assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the
oscillations.
Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results
allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the
reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape
fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in
future analyses of vole dynamics
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