2,358 research outputs found

    Experimental Status of Proton Decay

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75547/1/j.1749-6632.1986.tb52442.x.pd

    Документи Державного архіву Чернігівської області як джерело захисту прав жертв нацистського окупаційного режиму

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    The retention of phosphorus in surface waters through co-precipitation of phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich groundwater is not well understood. We developed an experimental field set-up to study Fe(II) oxidation and P immobilization along the flow-path from groundwater into surface water in an agricultural experimental catchment of a small lowland river. We physically separated tube drain effluent from groundwater discharge before it entered a ditch in an agricultural field. Through continuous discharge measurements and weekly water quality sampling of groundwater, tube drain water, exfiltrated groundwater, and surface water, we investigated Fe(II) oxidation kinetics and P immobilization processes. The oxidation rate inferred from our field measurements closely agreed with the general rate law for abiotic oxidation of Fe(II) by O<sub>2</sub>. Seasonal changes in climatic conditions affected the Fe(II) oxidation process. Lower pH and lower temperatures in winter (compared to summer) resulted in low Fe oxidation rates. After exfiltration to the surface water, it took a couple of days to more than a week before complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates were much higher. The Fe concentrations in the exfiltrated groundwater were low, indicating that dissolved Fe(II) is completely oxidized prior to inflow into a ditch. While the Fe oxidation rates reduce drastically from summer to winter, P concentrations remained high in the groundwater and an order of magnitude lower in the surface water throughout the year. This study shows very fast immobilization of dissolved P during the initial stage of the Fe(II) oxidation process which results in P-depleted water before Fe(II) is completely depleted. This cannot be explained by surface complexation of phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox gradients seems an important geochemical mechanism in the transformation of dissolved phosphate to structural phosphate and, therefore, a major control on the P retention in natural waters that drain anaerobic aquifers

    Planning and control in a manual collision avoidance task by children with hemiparesis

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    We examined whether deficits in planning and control during a manual collision avoidance task in children with hemiparesis are associated with damage to the left or right hemisphere (LHD and RHD). Children pushed a doll across a scale-size road between two approaching toy cars. Movement onset and velocity served as indicators of planning and control. In Experiment 1, children with hemiparesis collided more frequently, and controlled velocity less appropriately compared to typically-developing children. Children with LHD initiated their movement later than children with RHD. Experiment 2 compared the preferred and non-preferred hand of children with LHD and RHD. Children with RHD crossed less with their non-preferred hand, while children with LHD initiated later than children with RHD. Moreover, the groups showed differences in velocity control. It is argued that planning deficits may be related to LHD. The hypothesized association between control deficits and RHD, however, was not confirmed

    Uncertainty in soil data can outweigh climate impact signals in crop yield simulations

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    Global gridded crop models (GGCMs) are increasingly used for agro-environmental assessments and estimates of climate change impacts on food production. Recently, the influence of climate data and weather variability on GGCM outcomes has come under detailed scrutiny, unlike the influence of soil data. Here we compare yield variability caused by the soil type selected for GGCM simulations to weather-induced yield variability. Without fertilizer application, soil-type-related yield variability generally outweighs the simulated inter-annual variability in yield due to weather. Increasing applications of fertilizer and irrigation reduce this variability until it is practically negligible. Importantly, estimated climate change effects on yield can be either negative or positive depending on the chosen soil type. Soils thus have the capacity to either buffer or amplify these impacts. Our findings call for improvements in soil data available for crop modelling and more explicit accounting for soil variability in GGCM simulations

    Antibodies against p53 are associated with poor prognosis of colorectal cancer.

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    Mutation of the p53 gene is a common event in colorectal cancer. This alteration can result in cellular accumulation of p53 and may also induce p53 antibodies. Accumulation of p53 in tumour cells has been associated with poor prognosis of colorectal cancer. We tested preoperative sera from 255 patients with colorectal cancer by enzyme-linked immunosorbent assay (ELISA). A total of 70.2% had reactivity that was higher than the 'low' control serum. Employing a cut-off level of 10% of the 'high' control sample, 25.5% of the patients were positive for p53 antibodies. The presence of p53 antibodies correlated with the following prognostic factors: histological differentiation grade, shape of the tumour, and tumour invasion into blood vessels. Patients with p53 antibodies were shown to have decreased survival and decreased disease-free survival. Specifically for patients with cancer stage A and B1 the presence of p53 antibodies selected a subgroup with poor prognosis

    Deletion of the ghrelin receptor GHSR corrects the trabecular, but not the cortical bone changes in the femoral head of ob/ob mice

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    Background: There exists an intriguing and complex relationship between fat and bone cells with respect to aging and osteoporosis, which is mediated in part by leptin. Genetically obese mice (ob/ob), that lack leptin, have aheterogeneous bone phenotype, with differential effects on cortical and trabecular compartments. Besides its role in bone metabolism, leptin is most well known for its anorexigenic properties. Opposed in action to leptin is ghrelin, a potent orexigenic peptide hormone derived from the stomach. Ghrelin and leptin also act as each other’s antagonists in gonadal and immune system function.Objective: To determine if ghrelin opposes leptin action on bone metabolism.Methods: Characterization of femoral micro-architecture in 6 months old male wild type, ob/ob, ghrelin receptor knockout (Ghsr -/-), and ob/ob.Ghsr-/- mice using micro-computed tomography.Results: Deletion of Ghsr alone did not significantly alter bone micro-architecture in wild type mice. Deletion of leptin reduced cortical volume and thickness in the femoral head of wild type mice, while it increased endocortical volume. Tissue volume remained unaffected. Conversely, deletion of leptin increased trabecular bone volume, trabecular number and connectivity in wild type mice. Additional deletion of Ghsr in ob/ob mice restored the changes to wild type levels in trabecular bone, but not in cortical bone (all not significant).Conclusion: We found that leptin deficiency has a negative effect on cortical and a positive effect on trabecular bone micro-architecture, confirming the heterogeneous skeletal effects observed by others in ob/ob mice. Knocking out ghrelin signaling compensates for the effect of leptin deficiency on trabecular bone. These observations demonstrate the positive activity of ghrelin signaling in bone, and suggest that ghrelin and leptin have opposing actions on bone metabolism

    Scoping literature review and focus groups with healthcare professionals on psychosocial and lifestyle assessments for childhood obesity care

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    Background: Childhood obesity is a complex disease resulting from the interaction of multiple factors. The effective management of childhood obesity requires assessing the psychosocial and lifestyle factors that may play a role in the development and maintenance of obesity. This study centers on available scientific literature on psychosocial and lifestyle assessments for childhood obesity, and experiences and views of healthcare professionals with regard to assessing psychosocial and lifestyle factors within Dutch integrated care. Methods: Two methods were used. First, a scoping review (in PubMed, Embase, PsycInfo, IBSS, Scopus and Web of Science) was performed by systematically searching for scientific literature on psychosocial and lifestyle assessments for childhood obesity. Data were analysed by extracting data in Microsoft Excel. Second, focus group discussions were held with healthcare professionals from a variety of disciplines and domains to explore their experiences and views about assessing psychosocial and lifestyle factors within Dutch integrated care. Data were analysed using template analysis, complemented with open coding in MAXQDA. Results: The results provide an overview of relevant psychosocial and lifestyle factors that should be assessed and were classified as child, family, parental and lifestyle (e.g. nutrition, physical activity and sleep factors) and structured into psychological and social aspects. Insights into how to assess psychosocial and lifestyle factors were identified as well, including talking about psychosocial factors, lifestyle and weight; the professional-patient relationship; and attitudes of healthcare professionals. Conclusions: This study provides an overview of psychosocial and lifestyle factors that should be identified within the context of childhood obesity care, as they may contribute to the development and maintenance of obesity. The results highlight the importance of both what is assessed and how it is assessed. The results of this study can be used to develop practical tools for facilitating healthcare professionals in conducting a psychosocial and lifestyle assessment.</p