3,919 research outputs found

    YOUNG STARS IN AN OLD BULGE: A NATURAL OUTCOME OF INTERNAL EVOLUTION IN THE MILKY WAY

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    The center of our disk galaxy, the Milky Way, is dominated by a boxy/peanut-shaped bulge. Numerous studies of the bulge based on stellar photometry have concluded that the bulge stars are exclusively old. The perceived lack of young stars in the bulge strongly constrains its likely formation scenarios, providing evidence that the bulge is a unique population that formed early and separately from the disk. However, recent studies of individual bulge stars using the microlensing technique have reported that they span a range of ages, emphasizing that the bulge may not be a monolithic structure. In this Letter we demonstrate that the presence of young stars that are located predominantly nearer to the plane is expected for a bulge that has formed from the disk via dynamical instabilities. Using an N-body+ smoothed particle hydrodynamics simulation of a disk galaxy forming out of gas cooling inside a dark matter halo and forming stars, we find a qualitative agreement between our model and the observations of younger metal-rich stars in the bulge. We are also able to partially resolve the apparent contradiction in the literature between results that argue for a purely old bulge population and those that show a population comprised of a range in ages; the key is where to look

    An empirical investigation of users’ willingness to disclose personal health information in the context of wearable fitness devices

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    Wearable fitness device (WFD) has the capability to promote individuals’ healthy lifestyles because of real-time data monitoring capabilities. However, fitness device usability is a critical factor that determines whether users will be willing to disclose personal or health-related information on a large scale. The usability studies on WFDs are still limited in information systems (IS) literature. Therefore, this study investigates individuals’ willingness to disclose personal health information to use WFDs, in the light of the theory of planned behaviour and the health beliefs model. This study will help to “develop” a new perspective and a deeper understanding of factors influencing disclosing personal health information to use WFDs. Research data will be collected from M-Turk and the target population will be aged 18+ (years of age) and have experience in using WFDs. The results of this study will have significant implications for both IS researchers and IT managers. Keywords: Wearable fitness devices (WFDs), Personal health information (PHI), Theory of Planned Behavior (TPB), Health Belief Model (HBM)

    How cost-effective is biofortification in combating micronutrient malnutrition?: An ex-ante assessment

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    "Biofortification is increasingly seen as an additional tool to combat micronutrient malnutrition. This paper presents, for the first time, evidence on the costs and potential benefits of biofortification for a large number of countries in Africa, Asia and Latin America. We use a modification of the Disability-Adjusted Life Years framework to conclude that the intervention can make a significant impact on the burden of micronutrient deficiencies in the developing world, and can do so in a highly cost-effective manner." Authors' AbstractGeneral Biofortification, Cost-effectiveness, Micronutrient malnutrition,

    The Biomolecules Journal Club: Highlights on Recent Papers 1

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    We are glad to share with you our first Journal Club and to highlight some of the most interesting papers published recently. We hope we will tease your curiosity and encourage you to read full papers outside of your research area, which you may not have read otherwise. The Biomolecules Scientific Board wishes you an exciting read

    Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania

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    BACKGROUND: Streptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change. METHODS: We evaluated 602 cases of IPD reported in Philadelphia County, Pennsylvania, from 2002 to 2007. Poisson regression models incorporating seasonal smoothers were used to identify associations between weekly weather patterns and case counts. Associations between acute (dayto- day) environmental fluctuations and IPD occurrence were evaluated using a case-crossover approach. Effect modification across age and sex strata was explored, and meta-regression models were created using stratum-specific estimates for effect. RESULTS: IPD incidence was greatest in the wintertime, and spectral decomposition revealed a peak at 51.0 weeks, consistent with annual periodicity. After adjustment for seasonality, yearly increases in reporting, and temperature, weekly incidence was found to be associated with clear-sky UV index (IRR per unit increase in index: 0.70 [95% CI 0.54-0.91]). The effect of UV index was highest among young strata and decreased with age. At shorter time scales, only an association with increases in ambient sulphur oxides was linked to disease risk (OR for highest tertile of exposure 0.75, 95% CI 0.60 to 0.93). CONCLUSION: We confirmed the wintertime predominance of IPD in a major urban center. The major predictor of IPD in Philadelphia is extended periods of low UV radiation, which may explain observed wintertime seasonality. The mechanism of action of diminished light exposure on disease occurrence may be due to direct effects on pathogen survival or host immune function via altered 1,25-(OH)2-vitamin-D metabolism. These findings may suggest less diminution in future IPD risk with climate change than would be expected if wintertime seasonality was driven by temperature

    Haploinsufficiency for BRCA1 is associated with normal levels of DNA nucleotide excision repair in breast tissue and blood lymphocytes

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    BACKGROUND: Screening mammography has had a positive impact on breast cancer mortality but cannot detect all breast tumors. In a small study, we confirmed that low power magnetic resonance imaging (MRI) could identify mammographically undetectable tumors by applying it to a high risk population. Tumors detected by this new technology could have unique etiologies and/or presentations, and may represent an increasing proportion of clinical practice as new screening methods are validated and applied A very important aspect of this etiology is genomic instability, which is associated with the loss of activity of the breast cancer-predisposing genes BRCA1 and BRCA2. In sporadic breast cancer, however, there is evidence for the involvement of a different pathway of DNA repair, nucleotide excision repair (NER), which remediates lesions that cause a distortion of the DNA helix, including DNA cross-links. CASE PRESENTATION: We describe a breast cancer patient with a mammographically undetectable stage I tumor identified in our MRI screening study. She was originally considered to be at high risk due to the familial occurrence of breast and other types of cancer, and after diagnosis was confirmed as a carrier of a Q1200X mutation in the BRCA1 gene. In vitro analysis of her normal breast tissue showed no differences in growth rate or differentiation potential from disease-free controls. Analysis of cultured blood lymphocyte and breast epithelial cell samples with the unscheduled DNA synthesis assay (UDS) revealed no deficiency in nucleotide excision repair (NER). CONCLUSION: As new breast cancer screening methods become available and cost effective, patients such as this one will constitute an increasing proportion of the incident population, so it is important to determine whether they differ from current patients in any clinically important ways. Despite her status as a BRCA1 mutation carrier, and her mammographically dense breast tissue, we did not find increased cell proliferation or deficient differentiation potential in her breast epithelial cells, which might have contributed to her cancer susceptibility. Although NER deficiency has been demonstrated repeatedly in blood samples from sporadic breast cancer patients, analysis of blood cultured lymphocytes and breast epithelial cells for this patient proves definitively that heterozygosity for inactivation of BRCA1 does not intrinsically confer this type of genetic instability. These data suggest that the mechanism of genomic instability driving the carcinogenic process may be fundamentally different in hereditary and sporadic breast cancer, resulting in different genotoxic susceptibilities, oncogene mutations, and a different molecular pathogenesis

    A systematic review of the energy and climate impacts of teleworking

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    Information and communication technologies (ICTs) increasingly enable employees to work from home and other locations (‘teleworking’). This study explores the extent to which teleworking reduces the need to travel to work and the consequent impacts on economy-wide energy consumption. Methods/Design: The paper provides a systematic review of the current state of knowledge of the energy impacts of teleworking. This includes the energy savings from reduced commuter travel and the indirect impacts on energy consumption associated with changes in non-work travel and home energy consumption. The aim is to identify the conditions under which teleworking leads to a net reduction in economy-wide energy consumption, and the circumstances where benefits may be outweighed by unintended impacts. The paper synthesises the results of 39 empirical studies, identified through a comprehensive search of 9,000 published articles. Review results/Synthesis: Twenty six of the 39 studies suggest that teleworking reduces energy use, and only eight studies suggest that teleworking increases, or has a neutral impact on energy use. However, differences in the methodology, scope and assumptions of the different studies make it difficult to estimate ‘average’ energy savings. The main source of savings is the reduced distance travelled for commuting, potentially with an additional contribution from lower office energy consumption. However, the more rigorous studies that include a wider range of impacts (e.g. non-work travel or home energy use) generally find smaller savings. Discussion: Despite the generally positive verdict on teleworking as an energy-saving practice, there are numerous uncertainties and ambiguities about its actual or potential benefits. These relate to the extent to which teleworking may lead to unpredictable increases in non-work travel and home energy use that may outweigh the gains from reduced work travel. The available evidence suggests that economy-wide energy savings are typically modest, and in many circumstances could be negative or non-existent
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