Intensity-Weighted Physical Activity Volume and Risk of All-Cause and Cardiovascular Mortality: Does the Use of Absolute or Corrected Intensity Matter?

Background: Previous epidemiological studies examining the association between physical activity (PA) and mortality risk have measured absolute PA intensity using standard resting metabolic rate reference values that fail to consider individual differences. This study compared the risk of all-cause and cardiovascular mortality between absolute and corrected estimates of PA volume. Methods: 49,982 adults aged ≥40 years who participated in the Health Survey for England and Scottish Health Survey in 1994–2008 were included in our study. PA was classified as absolute or corrected metabolic equivalent (MET)-hours per week, taking participant’s weight, height, age, and sex into account. Cox regression models were used to examine the association between absolute and corrected PA volumes and all-cause and cardiovascular mortality. Results: The authors found no difference in the association between levels of PA and risk of all-cause and cardiovascular mortality for absolute and corrected MET-hours per week, although there was a consistent decrease in mortality risk with increasing PA. There was no difference in mortality when analyses were stratified by sex, age, and body mass index. Conclusions: The association between PA volume and risk of mortality was similar regardless of whether PA volume was estimated using absolute or corrected METs. There is no empirical justification against the use of absolute METs to estimate PA volume from questionnaires

Bibliografia sobre ecologia vegetal.

Botânica. Comunidades. Culturas temporárias. Culturas perenes. Decomposição. Doenças e pragas. Ecofisiologia. Fitogeografia. Fitossociologia. Florestas. Produtividade primaria. Sementes

Bibliografia sobre ecologia de pastagens.

Fatores físicos e edaficos. Gramineas. Leguminosas. Manejo. Pastagens cultivadas. Pastagens naturais. Produtividade primaria. Relação animal - planta

Revisiting the analytical solution approach to mixing-limited equilibrium multicomponent reactive transport using mixing ratios: identification of basis, fixing an error, and dealing with multiple minerals

Multicomponent reactive transport involves the solution of a system of nonlinear coupled partial differential equations. A number of methods have been developed to simplify the problem. In the case where all reactions are in instantaneous equilibrium and the mineral assemblage is constant in both space and time, de Simoni et al. (2007) provide an analytical solution that separates transport of aqueous components and minerals using scalar dissipation of Multicomponent reactive transport involves the solution of a system of nonlinear coupled partial differential equations. A number of methods have been developed to simplify the problem. In the case where all reactions are in instantaneous equilibrium and the mineral assemblage is constant in both space and time, de Simoni et al. (2007) provide an analytical solution that separates transport of aqueous components and minerals using scalar dissipation of "mixing ratios" between a number of boundary/initial solutions. In this approach, aqueous speciation is solved in conventional terms of primary and secondary species, and the mineral dissolution/precipitation rate is given in terms of the scalar dissipation and a chemical transformation term, both involving the secondary species associated with the mineral reaction. However, the identification of the secondary species is nonunique, and so it is not clear how to use the approach in general, a problem that is keenly manifest in the case of multiple minerals which may share aqueous ions. We address this problem by developing an approach to identify the secondary species required in the presence of one or multiple minerals. We also remedy a significant error in the de Simoni et al. (2007) approach. The result is a fixed and extended de Simoni et al. (2007) approach that allows construction of analytical solutions to multicomponent equilibrium reactive transport problems in which the mineral assemblage does not change in space or time and where the transport is described by closed-form solutions of the mixing ratios

Maternal body weight and first trimester screening for chromosomal anomalies

Prenatal risk ratios for Down syndrome adjust for maternal weight because maternal serum 2 biomarker levels decrease with increasing maternal weight. This is accomplished by converting 3 serum biomarker values into a multiple of the expected median (MOM) for women of the same 4 gestational age. Weight is frequently not recorded and the impact of using MOMs not adjusted for 5 weight for calculating risk ratios is unknown. The aim of this study is to examine the effect of 6 missing weight on first trimester Down syndrome risk ratios by comparing risk ratios calculated 7 using weight-unadjusted-and –adjusted MOMs. Findings at the population level indicate that the 8 impact of not adjusting for maternal weight on first trimester screening results for chromosomal 9 anomalies would lead to under-identification of 84 per 10,000 pregnancies.NHMR

Pressure control of magnetic order and excitations in the pyrochlore antiferromagnet MgCr2_{2}O4_{4}

MgCr$_{2}$O$_{4}$ is one of the best-known realizations of the pyrochlore-lattice Heisenberg antiferromagnet. The strong antiferromagnetic exchange interactions are perturbed by small further-neighbor exchanges such that this compound may in principle realize a spiral spin liquid (SSL) phase in the zero-temperature limit. However, a spin Jahn-Teller transition below $T_{\rm N} \approx 13$ K yields a complicated long-range magnetic order with multiple coexisting propagation vectors. We present neutron scattering and thermo-magnetic measurements of MgCr$_{2}$O$_{4}$ samples under applied hydrostatic pressure up to $P=1.7$ GPa demonstrating the existence of multiple close-lying nearly degenerate magnetic ground states. We show that the application of hydrostatic pressure increases the ordering temperature by around 0.8 K per GPa and increases the bandwidth of the magnetic excitations by around 0.5 meV per GPa. We also evidence a strong tendency for the preferential occupation of a subset of magnetic domains under pressure. In particular, we show that the $\boldsymbol{k}=(0,0,1)$ magnetic phase, which is almost negligible at ambient pressure, dramatically increases in spectral weight under pressure. This modifies the spectrum of magnetic excitations, which we interpret unambiguously as spin waves from multiple magnetic domains. Moreover, we report that the application of pressure reveals a feature in the magnetic susceptibility above the magnetostructural transition. We interpret this as the onset of a short-range ordered phase associated with $\boldsymbol{k}=(0,0,1)$, previously not observed in magnetometry measurements.Comment: 19 pages including supplementary information, 10 main figures 6 supplementary figure

Levels of soluble fms-like tyrosine kinase one in first trimester and outcomes of pregnancy: a systematic review

Angiogenic factors are involved in formation of new blood vessels required for placental development and function; and critical for fetal growth and development. Soluble fms-like tyrosine kinase 1(sFlt-1) is an anti-angiogenic protein that inhibits formation of new blood vessels resulting in potential pregnancy complications. The objective of this study was to undertake a systematic review to assess levels of sFlt-1 in early pregnancy and association with adverse pregnancy outcomes. PubMed and Medline databases and reference lists were searched up to July 2010. Inclusion criteria were pregnant women, blood sample taken during first trimester and assessment/reporting of sFlt-1 concentrations and subsequent pregnancy complications. Twelve relevant studies were identified of 71 to 668 women. No pooling of results was undertaken due to variation in sFlt-1 concentrations (range, 166-6,349 pg/ml amongst controls), samples used (serum, plasma), different summary statistics (mean, median, odds ratio) and outcome definitions applied. Levels of sFlt-1 were generally higher among women who developed preeclampsia (11 studies) or gestational hypertension (two studies), but not significantly different to normotensive women in most studies. There was no consistent pattern in association between sFlt-1 concentrations and fetal growth restriction (4 studies); and levels were non-significantly higher for women with postpartum bleeding (1 study) and significantly lower for stillbirths (1 study).This review found no clear evidence of an association between sFlt-1 levels in first trimester and adverse pregnancy outcomes. However, findings were affected by methodological, biological and testing variations between studies; highlighting the need for consistent testing of new biomarkers and reporting of outcome measures

First trimester screening of serum soluble fms-like tyrosine kinase-1 and placental growth factor predicting hypertensive disorders of pregnancy

AbstractObjectiveTo assess the accuracy of first trimester soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) in predicting pregnancy hypertension and pre-eclampsia; and compare with the accuracy of routinely collected maternal and clinical risk factors.Study designIn this population-based cohort study, serum sFlt-1 and PlGF levels were measured in first trimester in 2,681 women with singleton pregnancies in New South Wales, Australia.Main outcome measuresPrediction of pregnancy hypertension and pre-eclampsia.ResultsThere were 213 (7.9%) women with pregnancy hypertension, including 68 (2.5%) with pre-eclampsia. The area under the curve (AUC) for both sFlt-1 and PlGF was not different from chance, but combined was 0.55 (P=0.005). Parity and previous diagnosed hypertension had better predictive accuracy than serum biomarkers (AUC=0.64, P<0.001) and the predictive accuracy for all maternal and clinical information was fair (AUC=0.70, P<0.001 for pregnancy hypertension and AUC=0.74, P<0.001 for pre-eclampsia). Adding sFlt-1 and PlGF to maternal risk factors did not improve the ability of the models to predict pregnancy hypertension or pre-eclampsia.ConclusionsMaternal first trimester serum concentrations of sFlt-1 and PlGF do not predict hypertensive disorders in pregnancy any better than routinely collected clinical and maternal risk factor information. Screening for sFlt-1 and PlGF levels in early pregnancy would not identify those pregnancies at-risk