1,332 research outputs found
Four-Hundred-and-Ninety-Million-Year Record of Bacteriogenic Iron Oxide Precipitation at Sea-Floor Hydrothermal Vents
Fe oxide deposits are commonly found at hydrothermal vent sites at mid-ocean ridge and back-arc sea floor spreading centers, seamounts associated with these spreading centers, and intra-plate seamounts, and can cover extensive areas of the seafloor. These deposits can be attributed to several abiogenic processes and commonly contain micron-scale filamentous textures. Some filaments are cylindrical casts of Fe oxyhydroxides formed around bacterial cells and are thus unquestionably biogenic. The filaments have distinctive morphologies very like structures formed by neutrophilic Fe oxidizing bacteria. It is becoming increasingly apparent that Fe oxidizing bacteria have a significant role in the formation of Fe oxide deposits at marine hydrothermal vents. The presence of Fe oxide filaments in Fe oxides is thus of great potential as a biomarker for Fe oxidizing bacteria in modern and ancient marine hydrothermal vent deposits. The ancient analogues of modern deep-sea hydrothermal Fe oxide deposits are jaspers. A number of jaspers, ranging in age from the early Ordovician to late Eocene, contain abundant Fe oxide filamentous textures with a wide variety of morphologies. Some of these filaments are like structures formed by modern Fe oxidizing bacteria. Together with new data from the modern TAG site, we show that there is direct evidence for bacteriogenic Fe oxide precipitation at marine hydrothermal vent sites for at least the last 490 Ma of the Phanerozoic
Comparative effectiveness of monotherapies and combination therapies for patients with hypertension: protocol for a systematic review with network meta-analyses
BACKGROUND: Hypertension has been cited as the most common attributable risk factor for death worldwide, and in Canada more than one of every five adults had this diagnosis in 2007. In addition to different lifestyle modifications, such as diet and exercise, there exist many pharmaco-therapies from different drug classes which can be used to lower blood pressure, thereby reducing the risk of serious clinical outcomes. In moderate and severe cases, more than one agent may be used. The optimal mono- and combination therapies for mild hypertension and moderate/severe hypertension are unclear, and clinical guidelines provide different recommendations for first line therapy. The objective of this review is to explore the relative benefits and safety of different pharmacotherapies for management of non-diabetic patients with hypertension, whether of a mild or moderate to severe nature. METHODS/DESIGN: Searches involving MEDLINE and the Cochrane Database of Systematic Reviews will be used to identify related systematic reviews and relevant randomized trials. The outcomes of interest include myocardial infarction, stroke, incident diabetes, heart failure, overall and cardiovascular related death, and important side effects (cancers, depression, syncopal episodes/falls and sexual dysfunction). Randomized controlled trials will be sought. Two reviewers will independently screen relevant reviews, titles and abstracts resulting from the literature search, and also potentially relevant full-text articles in duplicate. Data will be abstracted and quality will be appraised by two team members independently. Conflicts at all levels of screening and abstraction will be resolved through team discussion. Random effect pairwise meta-analyses and network meta-analyses will be conducted where deemed appropriate. Analyses will be geared toward studying treatment of mild hypertension and moderate/severe hypertension separately. DISCUSSION: Our systematic review results will assess the extent of currently available evidence for single agent and multi-agent pharmacotherapies in patients with mild, moderate and severe hypertension, and will provide a rigorous and updated synthesis of a range of important clinical outcomes for clinicians, decision makers and patients. TRIAL REGISTRATION: PROSPERO Registration Number: CRD4201300445
Focus on vulnerable populations and promoting equity in health service utilization ––an analysis of visitor characteristics and service utilization of the Chinese community health service
Background Community health service in China is designed to provide a convenient and affordable primary health service for the city residents, and to promote health equity. Based on data from a large national study of 35 cities across China, we examined the characteristics of the patients and the utilization of community health institutions (CHIs), and assessed the role of community health service in promoting equity in health service utilization for community residents. Methods Multistage sampling method was applied to select 35 cities in China. Four CHIs were randomly chosen in every district of the 35 cities. A total of 88,482 visitors to the selected CHIs were investigated by using intercept survey method at the exit of the CHIs in 2008, 2009, 2010, and 2011. Descriptive analyses were used to analyze the main characteristics (gender, age, and income) of the CHI visitors, and the results were compared with that from the National Health Services Survey (NHSS, including CHIs and higher levels of hospitals). We also analyzed the service utilization and the satisfactions of the CHI visitors. Results The proportions of the children (2.4%) and the elderly (about 22.7%) were lower in our survey than those in NHSS (9.8% and 38.8% respectively). The proportion of the low-income group (26.4%) was apparently higher than that in NHSS (12.5%). The children group had the lowest satisfaction with the CHIs than other age groups. The satisfaction of the low-income visitors was slightly higher than that of the higher-income visitors. The utilization rate of public health services was low in CHIs. Conclusions The CHIs in China appears to fulfill the public health target of uptake by vulnerable populations, and may play an important role in promoting equity in health service utilization. However, services for children and the elderly should be strengthened
Does the majority always know best? Young children's flexible trust in majority opinion
Copying the majority is generally an adaptive social learning strategy but the majority does not always know best. Previous work has demonstrated young children's selective uptake of information from a consensus over a lone dissenter. The current study examined children's flexibility in following the majority: do they overextend their reliance on this heuristic to situations where the dissenting individual has privileged knowledge and should be trusted instead? Four- to six- year-olds (N = 103) heard conflicting claims about the identity of hidden drawings from a majority and a dissenter in two between-subject conditions: in one, the dissenter had privileged knowledge over the majority (he drew the pictures); in the other he did not (they were drawn by an absent third party). Overall, children were less likely to trust the majority in the Privileged Dissenter condition. Moreover, 5- and 6- year-olds made majority-based inferences when the dissenter had no privileged knowledge but systematically endorsed the dissenter when he drew the pictures. The current findings suggest that by 5 years, children are able to make an epistemic-based judgment to decide whether or not to follow the majority rather than automatically following the most common view
Cascading signaling pathways improve the fidelity of a stochastically and deterministically simulated molecular RS latch
<p>Abstract</p> <p>Background</p> <p>While biological systems have often been compared with digital systems, they differ by the strong effect of crosstalk between signals due to diffusivity in the medium, reaction kinetics and geometry. Memory elements have allowed the creation of autonomous digital systems and although biological systems have similar properties of autonomy, equivalent memory mechanisms remain elusive. Any such equivalent memory system, however, must silence the effect of crosstalk to maintain memory fidelity.</p> <p>Results</p> <p>Here, we present a system of enzymatic reactions that behaves like an RS latch (a simple memory element in digital systems). Using both a stochastic molecular simulator and ordinary differential equation simulator, we showed that crosstalk between two latches operating in the same spatial localization disrupts the memory fidelity of both latches. Crosstalk was reduced or silenced when simple reaction loops were replaced with multiple step or cascading reactions, showing that cascading signaling pathways are less susceptible to crosstalk.</p> <p>Conclusion</p> <p>Thus, the common biological theme of cascading signaling pathways is advantageous for maintaining the fidelity of a memory latch in the presence of crosstalk. The experimental implementation of such a latch system will lead to novel approaches to cell control using synthetic proteins and will contribute to our understanding of why cells behave differently even when given the same stimulus.</p
Pesticide exposure and lymphohaematopoietic cancers: a case-control study in an agricultural region (Larissa, Thessaly, Greece)
<p>Abstract</p> <p>Background</p> <p>The causality of lymphohaematopoietic cancers (LHC) is multifactorial and studies investigating the association between chemical exposure and LHC have produced variable results. The aim of this study was to investigate the relationships between exposure to pesticides and LHC in an agricultural region of Greece.</p> <p>Methods</p> <p>A structured questionnaire was employed in a hospital-based case control study to gather information on demographics, occupation, exposure to pesticides, agricultural practices, family and medical history and smoking. To control for confounders, backward conditional and multinomial logistic regression analyses were used. To assess the dose-response relationship between exposure and disease, the chi-square test for trend was used.</p> <p>Results</p> <p>Three hundred and fifty-four (354) histologically confirmed LHC cases diagnosed from 2004 to 2006 and 455 sex- and age-matched controls were included in the study. Pesticide exposure was associated with total LHC cases (OR 1.46, 95% CI 1.05-2.04), myelodysplastic syndrome (MDS) (OR 1.87, 95% CI 1.00-3.51) and leukaemia (OR 2.14, 95% CI 1.09-4.20). A dose-response pattern was observed for total LHC cases (P = 0.004), MDS (P = 0.024) and leukaemia (P = 0.002). Pesticide exposure was independently associated with total LHC cases (OR 1.41, 95% CI 1.00 - 2.00) and leukaemia (OR 2.05, 95% CI 1.02-4.12) after controlling for age, smoking and family history (cancers, LHC and immunological disorders). Smoking during application of pesticides was strongly associated with total LHC cases (OR 3.29, 95% CI 1.81-5.98), MDS (OR 3.67, 95% CI 1.18-12.11), leukaemia (OR 10.15, 95% CI 2.15-65.69) and lymphoma (OR 2.72, 95% CI 1.02-8.00). This association was even stronger for total LHC cases (OR 18.18, 95% CI 2.38-381.17) when eating simultaneously with pesticide application.</p> <p>Conclusions</p> <p>Lymphohaematopoietic cancers were associated with pesticide exposure after controlling for confounders. Smoking and eating during pesticide application were identified as modifying factors increasing the risk for LHC. The poor pesticide work practices identified during this study underline the need for educational campaigns for farmers.</p
Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015
SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation
Studying the Underlying Event in Drell-Yan and High Transverse Momentum Jet Production at the Tevatron
We study the underlying event in proton-antiproton collisions by examining
the behavior of charged particles (transverse momentum pT > 0.5 GeV/c,
pseudorapidity |\eta| < 1) produced in association with large transverse
momentum jets (~2.2 fb-1) or with Drell-Yan lepton-pairs (~2.7 fb-1) in the
Z-boson mass region (70 < M(pair) < 110 GeV/c2) as measured by CDF at 1.96 TeV
center-of-mass energy. We use the direction of the lepton-pair (in Drell-Yan
production) or the leading jet (in high-pT jet production) in each event to
define three regions of \eta-\phi space; toward, away, and transverse, where
\phi is the azimuthal scattering angle. For Drell-Yan production (excluding the
leptons) both the toward and transverse regions are very sensitive to the
underlying event. In high-pT jet production the transverse region is very
sensitive to the underlying event and is separated into a MAX and MIN
transverse region, which helps separate the hard component (initial and
final-state radiation) from the beam-beam remnant and multiple parton
interaction components of the scattering. The data are corrected to the
particle level to remove detector effects and are then compared with several
QCD Monte-Carlo models. The goal of this analysis is to provide data that can
be used to test and improve the QCD Monte-Carlo models of the underlying event
that are used to simulate hadron-hadron collisions.Comment: Submitted to Phys.Rev.
Measurement of the Dipion Mass Spectrum in X(3872) -> J/Psi Pi+ Pi- Decays
We measure the dipion mass spectrum in X(3872)--> J/Psi Pi+ Pi- decays using
360 pb-1 of pbar-p collisions at 1.96 TeV collected with the CDF II detector.
The spectrum is fit with predictions for odd C-parity (3S1, 1P1, and 3DJ)
charmonia decaying to J/Psi Pi+ Pi-, as well as even C-parity states in which
the pions are from Rho0 decay. The latter case also encompasses exotic
interpretations, such as a D0-D*0Bar molecule. Only the 3S1 and J/Psi Rho
hypotheses are compatible with our data. Since 3S1 is untenable on other
grounds, decay via J/Psi Rho is favored, which implies C=+1 for the X(3872).
Models for different J/Psi-Rho angular momenta L are considered. Flexibility in
the models, especially the introduction of Rho-Omega interference, enable good
descriptions of our data for both L=0 and 1.Comment: 7 pages, 4 figures -- Submitted to Phys. Rev. Let
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