1,437 research outputs found

    Extremely high He isotope ratios in MORB-source mantle from the proto-Iceland plume

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    The high <sup>3</sup>He/<sup>4</sup>He ratio of volcanic rocks thought to be derived from mantle plumes is taken as evidence for the existence of a mantle reservoir that has remained largely undegassed since the Earth's accretion. The helium isotope composition of this reservoir places constraints on the origin of volatiles within the Earth and on the evolution and structure of the Earth's mantle. Here we show that olivine phenocrysts in picritic basalts presumably derived from the proto-Iceland plume at Baffin Island, Canada, have the highest magmatic <sup>3</sup>He/<sup>4</sup>He ratios yet recorded. A strong correlation between <sup>3</sup>He/<sup>4</sup>He and <sup>87</sup>Sr/<sup>86</sup>Sr, <sup>143</sup>Nd/<sup>144</sup>Nd and trace element ratios demonstrate that the <sup>3</sup>He-rich end-member is present in basalts that are derived from large-volume melts of depleted upper-mantle rocks. This reservoir is consistent with the recharging of depleted upper-mantle rocks by small volumes of primordial volatile-rich lower-mantle material at a thermal boundary layer between convectively isolated reservoirs. The highest <sup>3</sup>He/<sup>4</sup>He basalts from Hawaii and Iceland plot on the observed mixing trend. This indicates that a <sup>3</sup>He-recharged depleted mantle (HRDM) reservoir may be the principal source of high <sup>3</sup>He/<sup>4</sup>He in mantle plumes, and may explain why the helium concentration of the 'plume' component in ocean island basalts is lower than that predicted for a two-layer, steady-state model of mantle structure

    Change in Composition of the Anopheles Gambiae Complex and its Possible Implications for the Transmission of Malaria and Lymphatic Filariasis in North-Eastern Tanzania.

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    A dramatic decline in the incidence of malaria due to Plasmodium falciparum infection in coastal East Africa has recently been reported to be paralleled (or even preceded) by an equally dramatic decline in malaria vector density, despite absence of organized vector control. As part of investigations into possible causes for the change in vector population density, the present study analysed the Anopheles gambiae s.l. sibling species composition in north-eastern Tanzania. The study was in two parts. The first compared current species complex composition in freshly caught An. gambiae s.l. complex from three villages to the composition reported from previous studies carried out 2-4 decades ago in the same villages. The second took advantage of a sample of archived dried An. gambiae s.l. complex specimens collected regularly from a fourth study village since 2005. Both fresh and archived dried specimens were identified to sibling species of the An. gambiae s.l. complex by PCR. The same specimens were moreover examined for Plasmodium falciparum and Wuchereria bancrofti infection by PCR. As in earlier studies, An. gambiae s.s., Anopheles merus and Anopheles arabiensis were identified as sibling species found in the area. However, both study parts indicated a marked change in sibling species composition over time. From being by far the most abundant in the past An. gambiae s.s. was now the most rare, whereas An. arabiensis had changed from being the most rare to the most common. P. falciparum infection was rarely detected in the examined specimens (and only in An. arabiensis) whereas W. bancrofti infection was prevalent and detected in all three sibling species. The study indicates that a major shift in An. gambiae s.l. sibling species composition has taken place in the study area in recent years. Combined with the earlier reported decline in overall malaria vector density, the study suggests that this decline has been most marked for An. gambiae s.s., and least for An. arabiensis, leading to current predominance of the latter. Due to differences in biology and vectorial capacity of the An. gambiae s.l. complex the change in sibling species composition will have important implications for the epidemiology and control of malaria and lymphatic filariasis in the study area

    Impact of inhaled corticosteroids on growth in children with asthma: systematic review and meta-analysis

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    Background: Long-term inhaled corticosteroids (ICS) may reduce growth velocity and final height of children with asthma. We aimed to evaluate the association between ICS use of >12 months and growth. Methods: We initially searched MEDLINE and EMBASE in July 2013, followed by a PubMed search updated to December 2014. We selected RCTs and controlled observational studies of ICS use in patients with asthma. We conducted random effects meta-analysis of mean differences in growth velocity (cm/year) or final height (cm) between groups. Heterogeneity was assessed using the I2 statistic. Results: We found 23 relevant studies (twenty RCTs and three observational studies) after screening 1882 hits. Meta-analysis of 16 RCTs showed that ICS use significantly reduced growth velocity at one year follow-up (mean difference -0.48 cm/year (95% CI -0.66 to -0.29)). There was evidence of a dose-response effect in three RCTs. Final adult height showed a mean reduction of -1.20 cm (95% CI -1.90 cm to -0.50 cm) with budesonide versus placebo in a high quality RCT. Meta-analysis of two lower quality observational studies revealed uncertainty in the association between ICS use and final adult height, pooled mean difference -0.85 cm (95% CI -3.35 to 1.65). Conclusion: Use of ICS for >12 months in children with asthma has a limited impact on annual growth velocity. In ICS users, there is a slight reduction of about a centimeter in final adult height, which when interpreted in the context of average adult height in England (175 cm for men and 161 cm for women), represents a 0.7% reduction compared to non-ICS users

    Strong signature of natural selection within an FHIT intron implicated in prostate cancer risk

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    Previously, a candidate gene linkage approach on brother pairs affected with prostate cancer identified a locus of prostate cancer susceptibility at D3S1234 within the fragile histidine triad gene (FHIT), a tumor suppressor that induces apoptosis. Subsequent association tests on 16 SNPs spanning approximately 381 kb surrounding D3S1234 in Americans of European descent revealed significant evidence of association for a single SNP within intron 5 of FHIT. In the current study, resequencing and genotyping within a 28.5 kb region surrounding this SNP further delineated the association with prostate cancer risk to a 15 kb region. Multiple SNPs in sequences under evolutionary constraint within intron 5 of FHIT defined several related haplotypes with an increased risk of prostate cancer in European-Americans. Strong associations were detected for a risk haplotype defined by SNPs 138543, 142413, and 152494 in all cases (Pearson's χ2 = 12.34, df 1, P = 0.00045) and for the homozygous risk haplotype defined by SNPs 144716, 142413, and 148444 in cases that shared 2 alleles identical by descent with their affected brothers (Pearson's χ2 = 11.50, df 1, P = 0.00070). In addition to highly conserved sequences encompassing SNPs 148444 and 152413, population studies revealed strong signatures of natural selection for a 1 kb window covering the SNP 144716 in two human populations, the European American (π = 0.0072, Tajima's D= 3.31, 14 SNPs) and the Japanese (π = 0.0049, Fay & Wu's H = 8.05, 14 SNPs), as well as in chimpanzees (Fay & Wu's H = 8.62, 12 SNPs). These results strongly support the involvement of the FHIT intronic region in an increased risk of prostate cancer. © 2008 Ding et al

    Mortality after Hospitalization for Pneumonia among Individuals with HIV, 1995–2008: A Danish Cohort Study

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    BACKGROUND: HIV-infected persons are at increased risk of pneumonia, even with highly active antiretroviral treatment (HAART). We examined the impact of pneumonia on mortality and identified prognostic factors for death among HIV-infected. METHODOLOGY/PRINCIPAL FINDINGS: In a nationwide, population-based cohort of individuals with HIV, we included persons hospitalized with pneumonia from the Danish National Hospital Registry and obtained mortality data from the Danish Civil Registration System. Comparing individuals with and without pneumonia, we used Poisson regression to estimate relative mortality and logistic regression to examine prognostic factors for death following pneumonia. From January 1, 1995, to July 1, 2008, we observed 699 episodes of first hospitalization for pneumonia among 4,352 HIV patients. Ninety-day mortality after pneumonia decreased from 22.4% (95% confidence interval [CI]: 16.5%-28.9%) in 1995-1996 to 8.4% (95% CI: 6.1%-11.6%) in 2000-2008. Mortality remained elevated for more than a year after hospitalization for pneumonia: adjusted mortality rate ratio 5.38 (95% CI: 4.27-6.78), 1.80 (95% CI: 1.36-2.37), and 1.62 (95% CI: 1.32-2.00) for days 0-90, 91-365, and 366+, respectively. The following variables predicted mortality within 90 days following hospitalization for pneumonia (adjusted Odds Ratios): male sex (3.77, 95% CI: 1.37-10.4), Charlson Comorbidity Index score > or = 2 (3.86, 95% CI: 2.19-6.78); no current HAART (3.58, 95% CI: 1.83-6.99); history of AIDS (2.46, 95% CI: 1.40-4.32); age per 10 year increase (1.43, 95% CI: 1.11-1.85); and CD4+ cell count < or = 200 (2.52, 95% CI: 1.37-4.65). CONCLUSIONS/SIGNIFICANCE: The first hospitalization for pneumonia among HIV-infected individuals was associated with elevated risk of death up to more than a year later. Use of HAART decreased the risk, independent of current CD4+ cell count. Prognosis following pneumonia improved over calendar time

    Type D personality is associated with increased metabolic syndrome prevalence and an unhealthy lifestyle in a cross-sectional Dutch community sample

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    <p>Abstract</p> <p>Background</p> <p>People with Type D-Distressed-personality have a general tendency towards increased negative affectivity (NA), while at the same time inhibiting these emotions in social situations (SI). Type D personality is associated with an increased risk of adverse outcomes in patients with cardiovascular disease. Whether Type D personality is a cardiovascular risk factor in healthy populations remains to be investigated. In the present study, the relations between Type D personality and classical cardiovascular risk factors, i.e. metabolic syndrome and lifestyle were investigated in a Dutch community sample.</p> <p>Methods</p> <p>In a cross-sectional study 1592 participants were included, aged 20-80 years. Metabolic syndrome was defined by self-report, following the International Diabetes Federation-IDF-guidelines including an increased waist circumference, dyslipidemia, hypertension, and diabetes. In addition lifestyle factors smoking, alcohol use, exercise and dietary habits were examined. Metabolic syndrome prevalence was stratified by Type D personality (a high score on both NA and SI), lifestyle and confounders age, gender, having a partner, higher education level, cardiac history, family history of cardiovascular disease.</p> <p>Results</p> <p>Metabolic syndrome was more prevalent in persons with a Type D personality (13% vs. 6%). Persons with Type D personality made poorer lifestyle choices, adhered less to the physical activity norm (OR = 1.5, 95%CI = 1.1-2.0, <it>p </it>= .02), had a less varied diet (OR = 0.50, 95%CI = 0.40-0.70, <it>p </it>< .0005), and were less likely to restrict their fat intake (OR = 0.70, 95%CI = 0.50-0.90, <it>p </it>= .01). Type D personality was related to a twofold increased risk of metabolic syndrome (OR = 2.2, 95%CI = 1.2-4.0, <it>p </it>= .011), independent of lifestyle factors and confounders.</p> <p>Conclusions</p> <p>Type D personality is related to an increased prevalence of metabolic syndrome and unhealthy lifestyle, which suggests both behavioral and biological vulnerability for development of cardiovascular disorders and diabetes.</p

    Violation of the transit-time limit toward generation of ultrashort electron bunches with controlled velocity chirp

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    Various methods to generate ultrashort electron bunches for the ultrafast science evolved from the simple configuration of two-plate vacuum diodes to advanced technologies such as nanotips or photocathodes excited by femtosecond lasers. In a diode either in vacuum or of solid-state, the transit-time limit originating from finite electron mobility has caused spatiotemporal bunch-collapse in ultrafast regime. Here, we show for the first time that abrupt exclusion of transit-phase is a more fundamental origin of the bunch-collapse than the transit-time limit. We found that by significantly extending the cathode-anode gap distance, thereby violating the transit-time limit, the conventional transit-time-related upper frequency barrier in diodes can be removed. Furthermore, we reveal how to control the velocity chirp of bunches leading to ballistic bunch-compression. Demonstration of 0.707 THz-, 46.4 femtosecond-bunches from a 50 mu m-wide diode in three-dimensional particle-in-cell simulations shows a way toward simple and compact sources of ultrafast electron bunches for diverse ultrafast sciences.ope

    Psychiatric disorders and urbanization in Germany

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    <p>Abstract</p> <p>Background</p> <p>Epidemiological studies over the last decade have supplied growing evidence of an association between urbanization and the prevalence of psychiatric disorders. Our aim was to examine the link between levels of urbanization and 12-month prevalence rates of psychiatric disorders in a nationwide German population study, controlling for other known risk factors such as gender, social class, marital status and the interaction variables of these factors with urbanization.</p> <p>Methods</p> <p>The Munich Composite International Diagnostic Interview (M-CIDI) was used to assess the prevalence of mental disorders (DSM-IV) in a representative sample of the German population (N = 4181, age: 18–65). The sample contains five levels of urbanization based on residence location.</p> <p>The epidemiological study was commissioned by the German Ministry of Research, Education and Science (BMBF) and approved by the relevant Institutional Review Board and ethics committee. Written informed consent was obtained for both surveys (core survey and Mental Health Supplement). Subjects did not get any financial compensation for their study participation.</p> <p>Results</p> <p>Higher levels of urbanization were linked to higher 12-month prevalence rates for almost all major psychiatric disorders (with the exception of substance abuse and psychotic disorders). The weighted prevalence percentages were highest in the most urbanized category. Alongside urbanization, female gender, lower social class and being unmarried were generally found to be associated with higher levels of psychopathology. The impact of urbanization on mental health was about equal (for almost all major psychiatric disorders) in young people and elderly people, men and women, and in married and single people. Only people from a low social class in the most urbanized settings had more somatoform disorders, and unmarried people in the most urbanized settings had more anxiety disorders.</p> <p>Conclusion</p> <p>Psychiatric disorders are more prevalent among the inhabitants of more urbanized areas. probably because of environmental stressors.</p
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