22,499 research outputs found

    (In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium

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    We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.Comment: More detailed figure

    Health Impacts and Economic Costs of Air Pollution in the Metropolitan Area of Skopje

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    Background: Urban outdoor air pollution, especially particulate matter, remains a major environmental health problem in Skopje, the capital of the former Yugoslav Republic of Macedonia. Despite the documented high levels of pollution in the city, the published evidence on its health impacts is as yet scarce. Methods: we obtained, cleaned, and validated Particulate Matter (PM) concentration data from five air quality monitoring stations in the Skopje metropolitan area, applied relevant concentration-response functions, and evaluated health impacts against two theoretical policy scenarios. We then calculated the burden of disease attributable to PM and calculated the societal cost due to attributable mortality. Results: In 2012, long-term exposure to PM2.5 (49.2 μg/m3) caused an estimated 1199 premature deaths (CI95% 821–1519). The social cost of the predicted premature mortality in 2012 due to air pollution was estimated at between 570 and 1470 million euros. Moreover, PM2.5 was also estimated to be responsible for 547 hospital admissions (CI95% 104–977) from cardiovascular diseases, and 937 admissions (CI95% 937–1869) for respiratory disease that year. Reducing PM2.5 levels to the EU limit (25 μg/m3) could have averted an estimated 45% of PM-attributable mortality, while achieving the WHO Air Quality Guidelines (10 μg/m3) could have averted an estimated 77% of PM-attributable mortality. Both scenarios would also attain significant reductions in attributable respiratory and cardiovascular hospital admissions. Conclusions: Besides its health impacts in terms of increased premature mortality and hospitalizations, air pollution entails significant economic costs to the population of Skopje. Reductions in PM2.5 concentrations could provide substantial health and economic gains to the city

    Holocene land-sea climatic links on the equatorial Pacific coast (Bay of Guayaquil, Ecuador)

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    Copyright © 2015 SAGE PublicationsWe analyzed the pollen content of a marine core located near the bay of Guayaquil in Ecuador to document the link between sea surface temperatures (SST) and changes in rainfall regimes on the adjacent continent during the Holocene. Based on the expansion/regression of five vegetation types, we observe three successive climatic patterns. In the first phase, between 11,700 and 7700 cal yr BP, the presence of a cloud (Andean) forest in the mid altitudes and mangroves in the estuary of the Guayas Basin, were associated with a maximum in boreal summer insolation, a northernmost position of the Intertropical Convergence Zone (ITCZ), a land- sea thermal contrast, and dryness. Between 7700 and 2850 cal yr BP, the expansion of the coastal herbs and the regression of the mangrove indicate a drier climate with weak ITCZ and low ENSO variability while austral winter insolation gradually increased. The interval between 4200 and 2850 cal yr BP was marked by the coolest and driest climatic conditions of the Holocene due to the weak influence of the ITCZ and a strengthening of the Humboldt Current. After 2850 cal yr BP, high variability and amplitude of the Andean forest changes occurred when ENSO frequency and amplitude increased, indicating high variability in land-sea connections. The ITCZ reached the latitude of Guayaquil only after 2500 cal yr BP inducing the bimodal precipitation regime we observe today. Our study shows that besides insolation, the ITCZ position and ENSO frequency, changes in eastern equatorial Pacific SSTs play a major role in determining the composition of the ecosystems and the hydrological cycle of the Ecuadorian Pacific coast and the Western Cordillera in Ecuador.Deutsche ForschungsgemeinschaftFrench Research Agenc

    An ideal mass assignment scheme for measuring the Power Spectrum with FFTs

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    In measuring the power spectrum of the distribution of large numbers of dark matter particles in simulations, or galaxies in observations, one has to use Fast Fourier Transforms (FFT) for calculational efficiency. However, because of the required mass assignment onto grid points in this method, the measured power spectrum \la |\delta^f(k)|^2\ra obtained with an FFT is not the true power spectrum P(k)P(k) but instead one that is convolved with a window function W(k)2|W(\vec k)|^2 in Fourier space. In a recent paper, Jing (2005) proposed an elegant algorithm to deconvolve the sampling effects of the window function and to extract the true power spectrum, and tests using N-body simulations show that this algorithm works very well for the three most commonly used mass assignment functions, i.e., the Nearest Grid Point (NGP), the Cloud In Cell (CIC) and the Triangular Shaped Cloud (TSC) methods. In this paper, rather than trying to deconvolve the sampling effects of the window function, we propose to select a particular function in performing the mass assignment that can minimize these effects. An ideal window function should fulfill the following criteria: (i) compact top-hat like support in Fourier space to minimize the sampling effects; (ii) compact support in real space to allow a fast and computationally feasible mass assignment onto grids. We find that the scale functions of Daubechies wavelet transformations are good candidates for such a purpose. Our tests using data from the Millennium Simulation show that the true power spectrum of dark matter can be accurately measured at a level better than 2% up to k=0.7kNk=0.7k_N, without applying any deconvolution processes. The new scheme is especially valuable for measurements of higher order statistics, e.g. the bi-spectrum,........Comment: 17 pages, 3 figures, Accepted for publication in ApJ,Matches the accepte

    SUNRISE/IMaX observations of convectively driven vortex flows in the Sun

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    We characterize the observational properties of the convectively driven vortex flows recently discovered on the quiet Sun, using magnetograms, Dopplergrams and images obtained with the 1-m balloon-borne Sunrise telescope. By visual inspection of time series, we find some 3.1e-3 vortices/(Mm^2 min), which is a factor of 1.7 larger than previous estimates. The mean duration of the individual events turns out to be 7.9 min, with a standard deviation of 3.2 min. In addition, we find several events appearing at the same locations along the duration of the time series (31.6 min). Such recurrent vortices show up in the proper motion flow field map averaged over the time series. The typical vertical vorticities are <= 6e-3 1/sec, which corresponds to a period of rotation of some 35 min. The vortices show a preferred counterclockwise sense of rotation, which we conjecture may have to do with the preferred vorticity impinged by the solar differential rotation.Comment: To appear in ApJL. 5 Figs, 4 pages. The two animations associated with the work can be downloaded from http://www.iac.es/proyecto/solarhr/imaxvortex.html References updated in V

    Levels and patterns of objectively assessed physical activity and compliance with different public health guidelines in university students

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    ArticleBackground Physical activity (PA) is associated with health enhancement. The aim of this study was to assess: 1) levels and patterns of PA in university students by using accelerometers; and 2) the percentage of fulfilment of PA recommendations for adults, according to different public health guidelines. Methods Observational cross-sectional study (Cuenca’s Adults Study) involving 296 (206 women) healthy Spanish university students aged 18–25 years old. Participants wore the ActiGraph GT1M accelerometer for seven consecutive days. Total PA, steps and time spent in sedentary time, light, moderate, vigorous, and moderate to vigorous PA (MVPA) was assessed, and the prevalence of sufficient PA was calculated according to various public health guidelines. Results No sex differences in total PA were found. University students were more sedentary during weekend days than weekdays (p<0.05). Only 30.3% of participants accumulated 30 min/day at least five days a week of MVPA. A total of 5.4% of students met the recommendation of 150 min/week of MVPA or 75 min/week of vigorous PA, in PA bouts of at least 10 min. using the same definition, but on five or more days a week, only 0.5% students were found to meet the recommendation. In addition, only 0.5% of students met the recommendation of 30 min/day of MVPA, at least five days a week and in bouts of at least 10 min. Finally, 28.1% of the students met the recommendation of 10,000 steps/day. Conclusions Our study shows a high incidence of sedentary time in university students. The number of students meeting PA recommendations significantly differed depending on the recommendation proposed. Specific strategies to promote PA in this population are necessary as well as an agreement as to which PA guidelines should be used.Fundación para la Investigación SanitariaMinistry of Health and Consumer AffairsInstituto de Salud Carlos IIIRed de Investigación en Actividades Preventivas y de Promoción de Salu

    Association between sleep-disordered breathing and breast cancer aggressiveness

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    Background Sleep-disordered breathing (SDB) has been associated with cancer aggressiveness, but studies focused on specific tumors are lacking. In this pilot study we investigated whether SDB is associated with breast cancer (BC) aggressiveness. Methods 83 consecutive women <65 years diagnosed with primary BC underwent a home respiratory polygraphy. Markers of SDB severity included the apnea-hypopnea index (AHI) and the 4% oxygen desaturation index (ODI4). The Ki67 proliferation index, lack of hormone receptors (HR-), Nottingham Histological Grade (NHG), and tumor stage were used as markers of BC aggressiveness. The association between SDB and molecular subtypes of BC was also assessed. Results The mean (SD) age was 48.8 (8.8) years and body mass index was 27.4 (5.4) Kg/m2. 42 women (50.6%) were post-menopausal. The median (IQR) AHI was 5.1 (2–9.4), and ODI4 was 1.5 (0.5–5.8). The median (IQR) AHI did not differ between the groups with Ki67>28% and Ki6728% and Ki67<29% (51.2% vs 52.3%, p = 0.90), HR- and HR+ (58.3% vs 49.1%, p = 0.47), NHG categories (p = 0.89), different tumor stages (p = 0.71), or molecular subtypes (p = 0.73). These results did not change when the ODI4 was used instead of the AHI. Conclusion Our results do not support an association between the presence or severity of SDB and BC aggressiveness.Asociación de Neumología y Cirugía Torácica del Sur (NEUMOSUR) 1/201

    HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals

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    Short- to mid-term magnetic phenomena on the stellar surface of M-type stars cannot only resemble the effects of planets in radial velocity data, but also may hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942 taken over the past five years and additional photometry to disentangle stellar activity effects from genuine Doppler signals as a result of the orbital motion of the star around the common barycenter with its planet. To achieve this, we use the common methods of pre-whitening, and treat the correlated red noise by a first-order moving average term and by Gaussian-process regression following an MCMC analysis. We identify the rotational period of the star at 16.3 days and discover a new super-Earth, GJ 3942 b, with an orbital period of 6.9 days and a minimum mass of 7.1 Me. An additional signal in the periodogram of the residuals is present but we cannot claim it to be related to a second planet with sufficient significance at this point. If confirmed, such planet candidate would have a minimum mass of 6.3 Me and a period of 10.4 days, which might indicate a 3:2 mean-motion resonance with the inner planet
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