851 research outputs found

    Ford's Procedure for Combining Multiple Sets of Partially Ordered Data

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66929/2/10.1177_001316447303300104.pd

    Evaluation and Refinement of the French Protein System (PDI) under Irish Conditions

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    End of Project ReportThe CP and DM degradability of grazed grass (between April and October, inclusive) and grass silage samples (differing in cut number and treatment) was determined using the in situ technique and the results obtained were used to calculate the PDIE and PDIN values. The degradability data on 12 concentrate ingredients from a previous study (Woods, 2000) were used to estimate PDIE and PDIN values for these feedstuffs. The mean PDIE and PDIN values determined for grass were 81 g/kg and 127 g/kg DM, respectively and for grass silage were 60 g/kg and 94 g/kg DM. Regression analysis resulted in equations to predict the PDIN of samples of grazed grass (PDIN = 3.8 + 0.628 CP) (R²= 0.999) and grass silage (PDIN = 5.9 + 0.605 CP) (R²= 0.997), and the PDIE of grazed grass (PDIE = 181.4 - 0.104 NDF - 0.195 ash - 0.047 OMD) (R²= 0.987) and grass silage (PDIE = 27.7 + 0.083 DMD - 0.147 CP) (R²= 0.812). The PDIE and PDIN values of 11 of the 12 concentrate ingredients were similar to those used in the French Tables but the maize distillers’ grains in this study and those used in France would appear to be quite different products. The response to PDIE and PDIN in the diet of lactating cows was evaluated and the effect of better balancing the PDIE and PDIN supply on the efficiency of N utilisation was assessed. Twenty autumn calving cows were blocked in a complete Latin Square design and assigned to four different diets varying in PDIN and PDIE content. Each of the four treatments consisted of a concentrate, maize silage and grass silage in the proportions 37:38:25 on a DM basis. There were 4 periods of 4-week duration each. Diet A contained 92 g/kg DM of PDIE and 116 g/kg DM of PDIN. Diet B contained 103 g/kg DM of PDIE and 122 g/kg DM of PDIN. Diet C and D over supplied PDIN at 137 g/kg and 153 g/kg, respectively relative to PDIE at 111 g/kg DM. Dry matter intake increased significantly with the excess dietary PDIN relative to PDIE but there were no significant differences in milk yield and composition. Decreasing the supply of PDIE in the diet (i.e. diet A vs. B) resulted in no significant effect on milk or constituent yields but did significantly reduce the efficiency (kg milk / kg DMI) of milk production. There was also a significant reduction in the efficiency of milk produced per kg DMI with increasing dietary concentrations of PDIN and increasing PDIN: PDIE balance (B>C>D). Increasing the dietary PDIN from 122 to 153 g/kg DMI increased urine N (+54%), faecal N (+11%) and plasma urea concentrations (+75%). The results indicate that the optimum concentration of dietary PDI is approximately 103 g/kg DM for cows producing about 35 kg of milk per day. A better balance between PDIE and PDIN supply improves the efficiency of conversion of DM to milk and dietary protein

    The role of the built environment in explaining educational inequalities in walking and cycling among adults in the Netherlands

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    Background: This study examined whether characteristics of the residential built environment (i.e. population density, level of mixed land use, connectivity, accessibility of facilities, accessibility of green) contributed to educational inequalities in walking and cycling among adults. Methods: Data from participants (32-82 years) of the 2011 survey of the Dutch population-based GLOBE study were used (N = 2375). Highest attained educational level (independent variable) and walking for transport, cycling for transport, walking in leisure time and cycling in leisure time (dependent variables) were self-reported in the survey. GIS-systems were used to obtain spatial data on residential built environment characteristics. A four-step mediation-based analysis with log-linear regression models was used to examine to contribution of the residential built environment to educational inequalities in walking and cycling. Results: As compared to the lowest educational group, the highest educational group was more likely to cycle for transport (RR 1.13, 95% CI 1.04-1.23), walk in leisure time (RR 1.12, 95% CI 1.04-1.21), and cycle in leisure time (RR 1.12, 95% CI 1.03-1.22). Objective built environment characteristics were related to these outcomes, but contributed minimally to educational inequalities in walking and cycling. On the other hand, compared to the lowest educational group, the highest educational group was less likely to walk for transport (RR 0.91, 95% CI 0.82-1.01), which could partly be attributed to differences in the built environment. Conclusion: This study found that objective built environment characteristics contributed minimally to educational inequalities in walking and cycling in the Netherlands

    Compaction of fibrin clots reveals the antifibrinolytic effect of factor XIII

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    Essentials Factor XIIIa inhibits fibrinolysis by forming fibrin-fibrin and fibrin-inhibitor cross-links. Conflicting studies about magnitude and mechanisms of inhibition have been reported. Factor XIIIa most strongly inhibits lysis of mechanically compacted or retracted plasma clots. Cross-links of α2-antiplasmin to fibrin prevent the inhibitor from being expelled from the clot. Summary: Background Although insights into the underlying mechanisms of the effect of factor XIII on fibrinolysis have improved considerably in the last few decades, in particular with the discovery that activated FXIII (FXIIIa) cross-links α2-antiplasmin to fibrin, the topic remains a matter of debate. Objective To elucidate the mechanisms of the antifibrinolytic effect of FXIII. Methods and Results Platelet-poor plasma clot lysis, induced by the addition of tissue-type plasminogen activator, was measured in the presence or absence of a specific FXIIIa inhibitor. Both in a turbidity assay and in a fluorescence assay, the FXIIIa inhibitor had only a small inhibitory effect: 1.6-fold less tissue-type plasminogen activator was required for 50% clot lysis in the presence of the FXIIIa inhibitor. However, when the plasma clot was compacted by centrifugation, the FXIIIa inhibitor had a strong inhibitory effect, with 7.7-fold less tissue-type plasminogen activator being required for 50% clot lysis in the presence of the FXIIIa inhibitor. In both experiments, the effects of the FXIIIa inhibitor were entirely dependent on the cross-linking of α2-antiplasmin to fibrin. The FXIIIa inhibitor reduced the amount of α2-antiplasmin present in the compacted clots from approximately 30% to < 4%. The results were confirmed with experiments in which compaction was achieved by platelet-mediated clot retraction. Conclusions Compaction or retraction of fibrin clots reveals the strong antifibrinolytic effect of FXIII. This is explained by the cross-linking of α2-antiplasmin to fibrin by FXIIIa, which prevents the plasmin inhibitor from being fully expelled from the clot during compaction/retraction

    Interactions among Amazon land use, forests and climate: prospects for a near-term forest tipping point

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    Some model experiments predict a large-scale substitution of Amazon forest by savannah-like vegetation by the end of the twenty-first century. Expanding global demands for biofuels and grains, positive feedbacks in the Amazon forest fire regime and drought may drive a faster process of forest degradation that could lead to a near-term forest dieback. Rising worldwide demands for biofuel and meat are creating powerful new incentives for agro-industrial expansion into Amazon forest regions. Forest fires, drought and logging increase susceptibility to further burning while deforestation and smoke can inhibit rainfall, exacerbating fire risk. If sea surface temperature anomalies (such as El Niño episodes) and associated Amazon droughts of the last decade continue into the future, approximately 55% of the forests of the Amazon will be cleared, logged, damaged by drought or burned over the next 20 years, emitting 15–26 Pg of carbon to the atmosphere. Several important trends could prevent a near-term dieback. As fire-sensitive investments accumulate in the landscape, property holders use less fire and invest more in fire control. Commodity markets are demanding higher environmental performance from farmers and cattle ranchers. Protected areas have been established in the pathway of expanding agricultural frontiers. Finally, emerging carbon market incentives for reductions in deforestation could support these trends

    Observation Versus Embolization in Patients with Blunt Splenic Injury after Trauma: A Propensity Score Analysis

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    Background: Non-operative management (NOM) is the standard of care in hemodynamically stable patients with blunt splenic injury after trauma. Splenic artery embolization (SAE) is reported to increase observation success rate. Studies demonstrating improved splenic salvage rates with SAE primarily compared SAE with historical controls. The aim of this study was to investigate whether SAE improves success rate compared to observation alone in contemporaneous patients with blunt splenic injury. Methods: We included adult patients with blunt splenic injury admitted to five Level 1 Trauma Centers between January 2009 and December 2012 and selected for NOM. Successful treatment was defined as splenic salvage and no splenic re-intervention. We calculated propensity scores, expressing the probability of undergoing SAE, using multivariable logistic regression and created five strata based on the quintiles of the propensity score distribution. A weighted relative risk (RR) was calculated across strata to express the chances of success with SAE. Results: Two hundred and six patients were included in the study. Treatment was successful in 180 patients: 134/146 (92 %) patients treated with observation and 48/57 (84 %) patients treated with SAE. The weighted RR for success with SAE was 1.17 (0.94-1.45); for complications, the weighted RR was 0.71 (0.41-1.22). The mean number of transfused blood products was 4.4 (SD 9.9) in the observation group versus 9.1 (SD 17.2) in the SAE group. Conclusions: After correction for confounders with propensity score stratification technique, there was no significant difference between embolization and observation alone with regard to successful treatment in patients with blunt splenic injury after trauma

    Decoration of Fibrin with Extracellular Chaperones

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    BACKGROUND:  Many proteins bind to fibrin during clot formation in plasma. We previously identified by mass spectrometry the most abundant proteins that noncovalently bind to fibrin clots. Several of these proteins (e.g., apolipoprotein J/clusterin, haptoglobin, α2-macroglobulin, α1-antitrypsin) can act as extracellular chaperones. OBJECTIVE:  We hypothesize that clot-binding proteins may interact with fibrin as chaperones. The goal of this study is to test this hypothesis and to investigate the origin of the cross-β or amyloid structures in fibrin clots, which are associated with protein unfolding. METHODS AND RESULTS:  A thioflavin T assay was used to detect cross-β structures. A steadily increasing amount was measured in the fibrinogen fraction of plasma during heat stress, a standard treatment to induce unfolding of proteins. Heat-stressed plasma was clotted and clot-bound proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results showed that the amounts of the clot-bound proteins were related to the duration of the heat stress. This indicates that cross-β structures in unfolded fibrin(ogen) are involved in clot binding of the proteins, which supports our chaperone hypothesis. A contributing role of fibrin formation itself was studied by clotting purified fibrinogen with thrombin in the presence of thioflavin T. The fluorescence intensity increased in time in the presence of thrombin, but did not increase in its absence. This provides evidence for the generation of cross-β structures during fibrin formation. CONCLUSION:  Fibrin clots generated in plasma are decorated with extracellular chaperones. The binding of these chaperones involves cross-β structures originating both from unfolded fibrinogen and from fibrin formation

    The Quark-Photon Vertex and the Pion Charge Radius

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    The rainbow truncation of the quark Dyson-Schwinger equation is combined with the ladder Bethe-Salpeter equation for the dressed quark-photon vertex to study the low-momentum behavior of the pion electromagnetic form factor. With model gluon parameters previously fixed by the pion mass and decay constant, the pion charge radius rπr_\pi is found to be in excellent agreement with the data. When the often-used Ball-Chiu Ansatz is used to construct the quark-photon vertex directly from the quark propagator, less than half of rπ2r_\pi^2 is generated. The remainder of rπ2r^2_\pi is seen to be attributable to the presence of the ρ\rho-pole in the solution of the ladder Bethe-Salpeter equation.Comment: 21 pages, 9 figure
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