291 research outputs found
Upper limits on K-band polarization in three high-redshift radio galaxies: LBDS 53W091, 3C 441 and MRC 0156-252
We present the results of K-band imaging polarimetry of three radio galaxies,
including the very red and apparently old z=1.55 galaxy 53W091. We find weak
evidence for polarization in components of 3C 441 and in the south-east
companion of 53W091, but no evidence of significant polarization in 53W091
itself. We also find strong evidence that MRC 0156-252 is unpolarised. We
present upper limits for the K-band polarization of all three sources. For
53W091, the lack of significant K-band polarization provides further confidence
that its red R-K colour can be attributed to a mature stellar population,
consistent with the detailed analyses of its ultraviolet spectral-energy
distribution which indicate a minimum age of 2-3.5 Gyr.Comment: 7 pages, 3 postscript figures. In press at MNRA
The role of c-Jun in controlling the EPAC1-dependent induction of the SOCS3 gene in HUVECs
The cyclic AMP sensor, EPAC1, activates AP1-mediated transcription in HUVECs. Correspondingly, induction of the SOCS3 minimal promoter by EPAC1 requires a single AP1 site that constitutively binds phosphorylated (Ser63) c-Jun in DNA-pull-down assays. c-Jun (Ser63) becomes further phosphorylated following cyclic AMP stimulation and specific activation of protein kinase A (PKA), but not through selective activation of EPAC1. Moreover, despite a requirement for c-Jun for SOCS3 induction in fibroblasts, phospho-null c-Jun (Ser63/73Ala) had little effect on SOCS3 induction by cyclic AMP in HUVECs. AP1 activation and SOCS3 induction by EPAC1 in HUVECs therefore occur independently of c-Jun phosphorylation on Ser63
Culex tarsalis is a competent vector species for Cache Valley virus
Background: Cache Valley virus (CVV) is a mosquito-borne orthobunyavirus endemic in North America. The virus is
an important agricultural pathogen leading to abortion and embryonic lethality in ruminant species, especially
sheep. The importance of CVV in human public health has recently increased because of the report of severe
neurotropic diseases. However, mosquito species responsible for transmission of the virus to humans remain to be
determined. In this study, vector competence of three Culex species mosquitoes of public health importance, Culex
pipiens, Cx. tarsalis and Cx. quinquefasciatus, was determined in order to identify potential bridge vector species
responsible for the transmission of CVV from viremic vertebrate hosts to humans.
Results: Variation of susceptibility to CVV was observed among selected Culex species mosquitoes tested in this
study. Per os infection resulted in the establishment of infection and dissemination in Culex tarsalis, whereas Cx.
pipiens and Cx. quinquefasciatus were highly refractory to CVV. Detection of viral RNA in saliva collected from
infected Cx. tarsalis provided evidence supporting its role as a competent vector.
Conclusions: Our study provided further understanding of the transmission cycles of CVV and identifies Cx. tarsalis
as a competent vector
The protein kinase C inhibitor, Ro-31-7459, is a potent activator of ERK and JNK MAP kinases in HUVECs and yet inhibits cyclic AMP-stimulated <i>SOCS-3</i> gene induction through inactivation of the transcription factor c-Jun
Induction of the suppressor of cytokine signalling 3 (SOCS-3) gene is vital to the normal control of inflammatory signalling. In order to understand these processes we investigated the role of the proto-oncogene component of the AP-1 transcription factor complex, c-Jun, in the regulation of SOCS-3 gene induction. We found that cyclic AMP stimulation of HUVECs promoted phosphorylation and activation of JNK MAP kinase and its substrate c-Jun. The JNK responsive element of the human SOCS-3 promoter mapped to a putative AP-1 site within 1000 bp of the transcription start site. The PKC inhibitors, GF-109203X, Gö-6983 and Ro-317549, were all found to inhibit AP-1 transcriptional activity, transcriptional activation of this minimal SOCS-3 promoter and SOCS-3 gene induction in HUVECs. Interestingly, Ro-317549 treatment was also found to promote PKC-dependent activation of ERK and JNK MAP kinases and promote JNK-dependent hyper-phosphorylation of c-Jun, whereas GF-109203X and Gö-6983 had little effect. Despite this, all three PKC inhibitors were found to be effective inhibitors of c-Jun DNA-binding activity. The JNK-dependent hyper-phosphorylation of c-Jun in response to Ro-317549 treatment of HUVECs does therefore not interfere with its ability to inhibit c-Jun activity and acts as an effective inhibitor of c-Jun-dependent SOCS-3 gene induction
Combined analysis of the integrated Sachs-Wolfe effect and cosmological implications
We present a global measurement of the integrated Sachs-Wolfe (ISW) effect
obtained by cross-correlating all relevant large scale galaxy data sets with
the cosmic microwave background radiation map provided by the Wilkinson
Microwave Anisotropy Probe. With these measurements, the overall ISW signal is
detected at the ~ 4.5 sigma level. We also examine the cosmological
implications of these measurements, particularly the dark energy equation of
state w, its sound speed, and the overall curvature of the Universe. The flat
LCDM model is a good fit to the data and, assuming this model, we find that the
ISW data constrain Omega_m = 0.20 +0.19 -0.11 at the 95% confidence level. When
we combine our ISW results with the latest baryon oscillation and supernovae
measurements, we find that the result is still consistent with a flat LCDM
model with w = -1 out to redshifts z > 1.Comment: 24 pages, 15 figures. Version accepted by PRD. Improved quasar data,
revised parameter constraint
The Practitioner\u27s Guide to Global Health: an interactive, online, open-access curriculum preparing medical learners for global health experiences
BACKGROUND: Short-term experiences in global health (STEGH) are increasingly common in medical education, as they can provide learners with opportunities for service, learning, and sharing perspectives. Academic institutions need high-quality preparatory curricula and mentorship to prepare learners for potential challenges in ethics, cultural sensitivity, and personal safety; however, availability and quality of these are variable.
OBJECTIVE: The objective of this study is to create and evaluate an open-access, interactive massive open online course (MOOC) that prepares learners to safely and effectively participate in STEGH, permits flexible and asynchronous learning, is free of charge, and provides a certificate upon successful completion.
METHODS: Global health experts from 8 countries, 42 institutions, and 7 specialties collaborated to create The Practitioner\u27s Guide to Global Health (PGGH): the first course of this kind on the edX platform. Demographic data, pre- and posttests, and course evaluations were collected and analyzed.
RESULTS: Within its first year, PGGH enrolled 5935 learners from 163 countries. In a limited sample of 109 learners, mean posttest scores were significantly improved (p \u3c 0.01). In the course\u27s second year, 213 sampled learners had significant improvement (p \u3c 0.001).
CONCLUSION: We created and evaluated the first interactive, asynchronous, free-of-charge global health preparation MOOC. The course has had significant interest from US-based and international learners, and posttest scores have shown significant improvement
Dating martian mafic crust; microstructurally constrained baddeleyite geochronology of enriched shergottites Northwest Africa (NWA) 7257, NWA 8679 and Zagami
This work was supported by Science and Technology Facilities Council grant [ST/S000291/1] to JRD.Baddeleyite (monoclinic; m-ZrO2) is a widespread accessory phase within shergottites. However, the effects of shock loading on baddeleyite U-Pb isotopic systematics, and therefore its reliability as a geochronometer within highly shocked lithologies, are less well constrained. To investigate the effects of shock metamorphism on baddeleyite U-Pb chronology, we have conducted high-resolution microstructural analysis and in-situ U-Pb isotopic measurements for baddeleyite within enriched basaltic shergottites Northwest Africa (NWA) 7257, NWA 8679 and Zagami. Electron backscatter diffraction (EBSD) analyses of baddeleyite reveal significant microstructural heterogeneity within individual thin sections, recording widespread partial to complete reversion from high-pressure (≥3.3 GPa) orthorhombic zirconia polymorphs. We define a continuum of baddeleyite microstructures into four groupings on the basis of microstructural characteristics, including rare grains that retain magmatic twin relationships. Uncorrected U-Pb isotopic measurements form Tera-Wasserburg discordia, yielding new 238U-206Pb discordia ages of 195 ± 15 Ma (n = 17) for NWA 7257 and 220 ± 23 Ma (n = 10) for NWA 8679. Critically, there is no resolvable link between baddeleyite microstructure and U-Pb isotope systematics, indicating negligible open-system behaviour of U-Pb during zirconia phase transformations. Instead, we confirm that high post-shock temperatures exert the greatest control on Pb mobility within shocked baddeleyite; in the absence of high post-shock temperatures, baddeleyite yield robust U-Pb isotope systematics and date the age of magmatic crystallization. Low bulk post-shock temperatures recorded within Zagami (≤220 °C), and suggested within NWA 7257 and NWA 8679 by baddeleyite microstructure and other petrological constraints, confirm that the previously derived baddeleyite age of Zagami records magmatic crystallization, and provide greater age diversity to 225 Ma to 160 Ma enriched shergottites. While our data yield no resolvable link between microstructure and U-Pb isotopic composition, we strongly recommend that microstructural analyses should represent an essential step of baddeleyite U-Pb chronology within planetary (e.g., martian, lunar, asteroidal) and shocked terrestrial samples, allowing full contextualisation prior to destructive isotopic techniques. Microstructurally constrained in-situ U-Pb analyses of baddeleyite thus define new opportunities for the absolute chronology of martian meteorites and, more broadly, shocked planetary materials.Publisher PDFPeer reviewe
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Racial and Geographic Variation in Effects of Maternal Education and Neighborhood-Level Measures of Socioeconomic Status on Gestational Age at Birth: Findings From the ECHO Cohorts
Preterm birth occurs at excessively high and disparate rates in the United States. In 2016, the National Institutes of Health (NIH) launched the Environmental influences on Child Health Outcomes (ECHO) program to investigate the influence of early life exposures on child health. Extant data from the ECHO cohorts provides the opportunity to examine racial and geographic variation in effects of individual- and neighborhood-level markers of socioeconomic status (SES) on gestational age at birth. The objective of this study was to examine the association between individual-level (maternal education) and neighborhood-level markers of SES and gestational age at birth, stratifying by maternal race/ethnicity, and whether any such associations are modified by US geographic region. Twenty-six ECHO cohorts representing 25,526 mother-infant pairs contributed to this disseminated meta-analysis that investigated the effect of maternal prenatal level of education (high school diploma, GED, or less; some college, associate\u27s degree, vocational or technical training [reference category]; bachelor\u27s degree, graduate school, or professional degree) and neighborhood-level markers of SES (census tract [CT] urbanicity, percentage of black population in CT, percentage of population below the federal poverty level in CT) on gestational age at birth (categorized as preterm, early term, full term [the reference category], late, and post term) according to maternal race/ethnicity and US region. Multinomial logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). Cohort-specific results were meta-analyzed using a random effects model. For women overall, a bachelor\u27s degree or above, compared with some college, was associated with a significantly decreased odds of preterm birth (aOR 0.72; 95% CI: 0.61-0.86), whereas a high school education or less was associated with an increased odds of early term birth (aOR 1.10, 95% CI: 1.00-1.21). When stratifying by maternal race/ethnicity, there were no significant associations between maternal education and gestational age at birth among women of racial/ethnic groups other than non-Hispanic white. Among non-Hispanic white women, a bachelor\u27s degree or above was likewise associated with a significantly decreased odds of preterm birth (aOR 0.74 (95% CI: 0.58, 0.94) as well as a decreased odds of early term birth (aOR 0.84 (95% CI: 0.74, 0.95). The association between maternal education and gestational age at birth varied according to US region, with higher levels of maternal education associated with a significantly decreased odds of preterm birth in the Midwest and South but not in the Northeast and West. Non-Hispanic white women residing in rural compared to urban CTs had an increased odds of preterm birth; the ability to detect associations between neighborhood-level measures of SES and gestational age for other race/ethnic groups was limited due to small sample sizes within select strata. Interventions that promote higher educational attainment among women of reproductive age could contribute to a reduction in preterm birth, particularly in the US South and Midwest. Further individual-level analyses engaging a diverse set of cohorts are needed to disentangle the complex interrelationships among maternal education, neighborhood-level factors, exposures across the life course, and gestational age at birth outcomes by maternal race/ethnicity and US geography
Cell-format-dependent mechanical damage in silicon anodes
It is generally believed that silicon-based anodes for Li-ion batteries would
benefit from stronger binders, as cyclic volume changes would not disrupt the
cohesion of the composite electrode. Here, we put this belief to the proof by
testing electrodes containing SiOx particles and an aromatic polyimide binder.
We observe that the electrodes can stretch laterally by as much as 6% during
the first cycle, indicating that internal stresses are high enough to induce
plastic deformation on the copper current collector. Remarkably, no coating
delamination is observed. Additional consequences were size-dependent: while
pouch-cell-sized electrodes developed wrinkles, coin-cell-sized ones remained
mostly smooth. We demonstrate that wrinkling of the current collector damages
the electrode coating, inactivating SiOx domains and accelerating capacity
fade. This size-dependent performance decay indicates that, in extreme cases,
testing outcomes are highly dependent on scale. Novel battery materials may
require testing at larger cell formats for complete validation
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