336 research outputs found

    Degradation of mangrove leaf litter by the tropical sesarmid crab Chiromanthes onychophorum

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    In high-diversity tropical mangrove swamps, the relationship between the breakdown to detritus of mangrove plant litter and secondary production of associated estuaries is little understood. This study examined one step in this relationship, the breakdown of mangrove leaf litter to detrital-sized particles by the sesarmid crab Chiromanthes onychophorum , locally very abundant in mangrove swamps of peninsular Malaysia. Contents of the proventriculus (stomach) and of the posterior hindgut, including rectum, were analyzed and particle sizes were measured. Gut contents consisted of more than 95% by volume of mangrove leaf fragments. Particles in the hindgut were of smaller mean size than those in the proventriculus. It is concluded that C. onychophorum consumes fallen leaves or their fragments, incompletely digests them, and returns them to the environment as fecal matter in a more finely-divided state than when they were ingested. C. onychophorum may therefore be a significant agent of mangrove leaf degradation to detrital-sized particles in swamp areas where it is abundant.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46633/1/227_2004_Article_BF00455032.pd

    Reactions of a Be-10 beam on proton and deuteron targets

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    The extraction of detailed nuclear structure information from transfer reactions requires reliable, well-normalized data as well as optical potentials and a theoretical framework demonstrated to work well in the relevant mass and beam energy ranges. It is rare that the theoretical ingredients can be tested well for exotic nuclei owing to the paucity of data. The halo nucleus Be-11 has been examined through the 10Be(d,p) reaction in inverse kinematics at equivalent deuteron energies of 12,15,18, and 21.4 MeV. Elastic scattering of Be-10 on protons was used to select optical potentials for the analysis of the transfer data. Additionally, data from the elastic and inelastic scattering of Be-10 on deuterons was used to fit optical potentials at the four measured energies. Transfers to the two bound states and the first resonance in Be-11 were analyzed using the Finite Range ADiabatic Wave Approximation (FR-ADWA). Consistent values of the spectroscopic factor of both the ground and first excited states were extracted from the four measurements, with average values of 0.71(5) and 0.62(4) respectively. The calculations for transfer to the first resonance were found to be sensitive to the size of the energy bin used and therefore could not be used to extract a spectroscopic factor.Comment: 16 Pages, 10 figure

    Physical theory of the twentieth century and contemporary philosophy

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    It has been shown that the criticism of Pauli as well as of Susskind and Glogover may be avoided if the standard quantum-mechanical mathematical model has been suitably extended. There is not more any reason for Einstein's citicism, either, if in addition to some new results concerning Bell's inequalities and Belifante's argument are taken into account. The ensemble interpretation of quantum mechanics (or the hidden-variable theory) should be preferred, which is also supported by the already published results of experiments with three polarizers. Greater space in the text has been devoted also to the discussion of epistemological problems and some philosophical consequences.Comment: 12 page

    Performance of random forests and logic regression methods using mini-exome sequence data

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    Machine learning approaches are an attractive option for analyzing large-scale data to detect genetic variants that contribute to variation of a quantitative trait, without requiring specific distributional assumptions. We evaluate two machine learning methods, random forests and logic regression, and compare them to standard simple univariate linear regression, using the Genetic Analysis Workshop 17 mini-exome data. We also apply these methods after collapsing multiple rare variants within genes and within gene pathways. Linear regression and the random forest method performed better when rare variants were collapsed based on genes or gene pathways than when each variant was analyzed separately. Logic regression performed better when rare variants were collapsed based on genes rather than on pathways

    Quantifying the Relationship between Capability and Health in Older People: Can't Map, Won't Map

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    BACKGROUND: Intuitively, health and capability are distinct but linked concepts. This study aimed to quantify the link between a measure of health status (EQ-5D-3L) and capability (ICECAP-O) using regression-based methods. METHODS: EQ-5D-3L and ICECAP-O data were collected from a sample of older people ( n = 584), aged over 65 years, requiring a hospital visit and/or care home resident, and recruited to one of 3 studies forming the Medical Crisis in Older People (MCOP) program in England. The link of EQ-5D-3L with 1) ICECAP-O tariff scores were estimated using ordinary least squares (OLS) or censored least absolute deviation (CLAD) regression models; and 2) ICECAP-O domain scores was estimated using multinomial logistic (MNL) regression. Mean absolute error (MAE), root mean squared error (RMSE), absolute difference (AD) between mean observed and estimated values, and the R(2) statistic were used to judge model performance. RESULTS: In this sample of older people ( n = 584), higher scores on the EQ-5D-3L were shown to be linked with higher ICECAP-O scores when using linear regression. An OLS-regression model was identified to be the best performing model with the lowest error statistics (AD = 0.0000; MAE = 0.1208; MSE = 0.1626) and highest goodness of fit ( R(2) = 0.3532); model performance was poor when predicting the lower ICECAP-O tariff scores. The three domains of the EQ-5D-3L showing a statistically significant quantifiable link with the ICECAP-O tariff score were self-care, usual activities, and anxiety/depression. CONCLUSION: A quantifiable, but weak, link between health (EQ-5D-3L) and capability (ICECAP-O) was identified. The findings from this study add further support that the ICECAP-O is providing complimentary information to the EQ-5D-3L. Mapping between the 2 measures is not advisable and the measures should not be used as direct substitutes to capture the impact of interventions in economic evaluations

    Use of near infrared reflectance spectroscopy to predict nitrogen uptake by winter wheat within fields with high variability in organic matter

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    In this study, the ability to predict N-uptake in winter wheat crops using NIR-spectroscopy on soil samples was evaluated. Soil samples were taken in unfertilized plots in one winter wheat field during three years (1997-1999) and in another winter wheat field nearby in one year (2000). Soil samples were analyzed for organic C content and their NIR-spectra. N-uptake was measured as total N-content in aboveground plant materials at harvest. Models calibrated to predict N-uptake were internally cross validated and validated across years and across fields. Cross-validated calibrations predicted N-uptake with an average error of 12.1 to 15.4 kg N ha-1. The standard deviation divided by this error (RPD) ranged between 1.9 and 2.5. In comparison, the corresponding calibrations based on organic C alone had an error from 11.7 to 28.2 kg N ha-1 and RPDs from 1.3 to 2.5. In three of four annual calibrations within a field, the NIR-based calibrations worked better than the organic C based calibrations. The prediction of N-uptake across years, but within a field, worked slightly better with an organic C based calibration than with a NIR based one, RPD = 1.9 and 1.7 respectively. Across fields, the corresponding difference was large in favour of the NIR-calibration, RPD = 2.5 for the NIR-calibration and 1.5 for the organic C calibration. It was concluded that NIR-spectroscopy integrates information about organic C with other relevant soil components and therefore has a good potential to predict complex functions of soils such as N-mineralization. A relatively good agreement of spectral relationships to parameters related to the N-mineralization of datasets across the world suggests that more general models can be calibrated

    A novel cardiovascular magnetic resonance risk score for predicting mortality following surgical aortic valve replacement

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    The increasing prevalence of patients with aortic stenosis worldwide highlights a clinical need for improved and accurate prediction of clinical outcomes following surgery. We investigated patient demographic and cardiovascular magnetic resonance (CMR) characteristics to formulate a dedicated risk score estimating long-term survival following surgery. We recruited consecutive patients undergoing CMR with gadolinium administration prior to surgical aortic valve replacement from 2003 to 2016 in two UK centres. The outcome was overall mortality. A total of 250 patients were included (68 ± 12Β years, male 185 (60%), with pre-operative mean aortic valve area 0.93 ± 0.32cm2, LVEF 62 ± 17%) and followed for 6.0 ± 3.3Β years. Sixty-one deaths occurred, with 10-year mortality of 23.6%. Multivariable analysis showed that increasing age (HR 1.04, P = 0.005), use of antiplatelet therapy (HR 0.54, P = 0.027), presence of infarction or midwall late gadolinium enhancement (HR 1.52 and HR 2.14 respectively, combined P = 0.12), higher indexed left ventricular stroke volume (HR 0.98, P = 0.043) and higher left atrial ejection fraction (HR 0.98, P = 0.083) associated with mortality and developed a risk score with good discrimination. This is the first dedicated risk prediction score for patients with aortic stenosis undergoing surgical aortic valve replacement providing an individualised estimate for overall mortality. This model can help clinicians individualising medical and surgical care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00930735 and ClinicalTrials.gov Identifier: NCT01755936

    Interleukin-17A Mediates Acquired Immunity to Pneumococcal Colonization

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    Although anticapsular antibodies confer serotype-specific immunity to pneumococci, children increase their ability to clear colonization before these antibodies appear, suggesting involvement of other mechanisms. We previously reported that intranasal immunization of mice with pneumococci confers CD4+ T cell–dependent, antibody- and serotype-independent protection against colonization. Here we show that this immunity, rather than preventing initiation of carriage, accelerates clearance over several days, accompanied by neutrophilic infiltration of the nasopharyngeal mucosa. Adoptive transfer of immune CD4+ T cells was sufficient to confer immunity to naΓ―ve RAG1βˆ’/βˆ’ mice. A critical role of interleukin (IL)-17A was demonstrated: mice lacking interferon-Ξ³ or IL-4 were protected, but not mice lacking IL-17A receptor or mice with neutrophil depletion. In vitro expression of IL-17A in response to pneumococci was assayed: lymphoid tissue from vaccinated mice expressed significantly more IL-17A than controls, and IL-17A expression from peripheral blood samples from immunized mice predicted protection in vivo. IL-17A was elicited by pneumococcal stimulation of tonsillar cells of children or adult blood but not cord blood. IL-17A increased pneumococcal killing by human neutrophils both in the absence and in the presence of antibodies and complement. We conclude that IL-17A mediates pneumococcal immunity in mice and probably in humans; its elicitation in vitro could help in the development of candidate pneumococcal vaccines

    Pneumococcal Capsular Polysaccharide Structure Predicts Serotype Prevalence

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    There are 91 known capsular serotypes of Streptococcus pneumoniae. The nasopharyngeal carriage prevalence of particular serotypes is relatively stable worldwide, but the host and bacterial factors that maintain these patterns are poorly understood. Given the possibility of serotype replacement following vaccination against seven clinically important serotypes, it is increasingly important to understand these factors. We hypothesized that the biochemical structure of the capsular polysaccharides could influence the degree of encapsulation of different serotypes, their susceptibility to killing by neutrophils, and ultimately their success during nasopharyngeal carriage. We sought to measure biological differences among capsular serotypes that may account for epidemiological patterns. Using an in vitro assay with both isogenic capsule-switch variants and clinical carriage isolates, we found an association between increased carriage prevalence and resistance to non-opsonic neutrophil-mediated killing, and serotypes that were resistant to neutrophil-mediated killing tended to be more heavily encapsulated, as determined by FITC-dextran exclusion. Next, we identified a link between polysaccharide structure and carriage prevalence. Significantly, non-vaccine serotypes that have become common in vaccinated populations tend to be those with fewer carbons per repeat unit and low energy expended per repeat unit, suggesting a novel biological principle to explain patterns of serotype replacement. More prevalent serotypes are more heavily encapsulated and more resistant to neutrophil-mediated killing, and these phenotypes are associated with the structure of the capsular polysaccharide, suggesting a direct relationship between polysaccharide biochemistry and the success of a serotype during nasopharyngeal carriage and potentially providing a method for predicting serotype replacement

    Can CAPTURE Be Used to Identify Undiagnosed Patients with Mild-To-Moderate COPD Likely to Benefit from Treatment?

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    Background: COPD Assessment in Primary Care To Identify Undiagnosed Respiratory Disease and Exacerbation Risk (CAPTUREβ„’) uses five questions and peak expiratory flow (PEF) thresholds (males ≀350 L/min; females ≀250 L/min) to identify patients with a forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC)11 60%–80% predicted) who may also benefit from diagnosis and treatment. Methods: Data from the CAPTURE development study were used to test its sensitivity (SN) and specificity (SP) differentiating mild-to-moderate COPD (n=73) from no COPD (n=87). SN and SP for differentiating all COPD cases (mild to severe; n=259) from those without COPD (n=87) were also estimated. The modified Medical Research Council (mMRC) dyspnea scale and COPD Assessment Test (CATβ„’) were used to evaluate symptoms and health status. Clinical Trial Registration: NCT01880177, https://ClinicalTrials.gov/ct2/show/NCT01880177?term=NCT01880177&rank=1. Results: Mean age (+SD): 61 (+10.5) years; 41% male. COPD: FEV1/FVC=0.60 (+0.1), FEV1% predicted=74% (+12.4). SN and SP for differentiating mild-to-moderate and non-COPD patients (n=160): Questionnaire: 83.6%, 67.8%; PEF (≀450 L/min; ≀350 L/min): 83.6%, 66.7%; CAPTURE (Questionnaire+PEF): 71.2%, 83.9%. COPD patients whose CAPTURE results suggested that diagnostic evaluation was warranted (n=52) were more likely to be symptomatic than patients whose results did not (n=21) (mMRC \u3e2: 37% vs 5%, p10: 86% vs 57%, p Conclusion: CAPTURE (450/350) may be useful for identifying symptomatic patients with mild-to-moderate airflow obstruction in need of diagnostic evaluation for COPD
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