14,765 research outputs found

    Calculation of geometric phases in electric dipole searches with trapped spin-1/2 particles based on direct solution of the Schr\"odinger equation

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    Pendlebury et al.\textit{et al.} [Phys. Rev. A 70\textbf{70}, 032102 (2004)] were the first to investigate the role of geometric phases in searches for an electric dipole moment (EDM) of elementary particles based on Ramsey-separated oscillatory field magnetic resonance with trapped ultracold neutrons and comagnetometer atoms. Their work was based on the Bloch equation and later work using the density matrix corroborated the results and extended the scope to describe the dynamics of spins in general fields and in bounded geometries. We solve the Schr\"odinger equation directly for cylindrical trap geometry and obtain a full description of EDM-relevant spin behavior in general fields, including the short-time transients and vertical spin oscillation in the entire range of particle velocities. We apply this method to general macroscopic fields and to the field of a microscopic magnetic dipole.Comment: 11 pages, 4 figure

    Diffuse gamma-ray background and cosmic-ray positrons from annihilating dark matter

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    We study the annihilating dark matter contribution to the extra-galactic diffuse gamma-ray background spectrum, motivated by the recent observations of cosmic-ray positron/electron anomalies. The observed diffuse gamma-ray flux provides stringent constraint on dark matter models and we present upper bounds on the annihilation cross section of the dark matter. It is found that for the case of cored dark matter halo profile, the diffuse gamma-rays give more stringent bound compared with gamma-rays from the Galactic center. The Fermi satellite will make the bound stronger.Comment: 20 pages, 11 figures; references added; to appear in PR

    Measures of Health-Related Quality of Life Outcomes in Pediatric Neurosurgery: Literature Review

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    Background Improving value in healthcare means optimizing outcomes and minimizing costs. The emerging pay-for-performance era requires understanding of the effect of healthcare services on health-related quality of life (HRQoL). Pediatric and surgical subspecialties have yet to fully integrate HRQoL measures into practice. The present study reviewed and characterized the HRQoL outcome measures across various pediatric neurosurgical diagnoses. Methods A literature review was performed by searching PubMed and Google Scholar with search terms such as “health-related quality of life” and “pediatric neurosurgery” and then including the specific pathologies for which a HRQoL instrument was found (e.g., “health-related quality of life” plus “epilepsy”). Each measurement was evaluated by content and purpose, relative strengths and weaknesses, and validity. Results We reviewed 68 reports. Epilepsy, brain tumor, cerebral palsy, spina bifida, hydrocephalus, and scoliosis were diagnoses found in reported studies that had used disease-specific HRQoL instruments. Information using general HRQoL instruments was also reported. Internal, test–retest, and/or interrater reliability varied across the instruments, as did face, content, concurrent, and/or construct validity. Few instruments were tested enough for robust reliability and validity. Significant variability was found in the usage of these instruments in clinical studies within pediatric neurosurgery. Conclusions The HRQoL instruments used in pediatric neurosurgery are currently without standardized guidelines and thus exhibit high variability in use. Clinicians should support the development and application of these methods to optimize these instruments, promote standardization of research, improve performance measures to reflect clinically modifiable and meaningful outcomes, and, ultimately, lead the national discussion in healthcare quality and patient-centered care

    CosmoDM and its application to Pan-STARRS data

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    The Cosmology Data Management system (CosmoDM) is an automated and flexible data management system for the processing and calibration of data from optical photometric surveys. It is designed to run on supercomputers and to minimize disk I/O to enable scaling to very high throughput during periods of reprocessing. It serves as an early prototype for one element of the ground-based processing required by the Euclid mission and will also be employed in the preparation of ground based data needed in the eROSITA X-ray all sky survey mission. CosmoDM consists of two main pipelines. The first is the single-epoch or detrending pipeline, which is used to carry out the photometric and astrometric calibration of raw exposures. The second is the co- addition pipeline, which combines the data from individual exposures into deeper coadd images and science ready catalogs. A novel feature of CosmoDM is that it uses a modified stack of As- tromatic software which can read and write tile compressed images. Since 2011, CosmoDM has been used to process data from the DECam, the CFHT MegaCam and the Pan-STARRS cameras. In this paper we shall describe how processed Pan-STARRS data from CosmoDM has been used to optically confirm and measure photometric redshifts of Planck-based Sunyaev-Zeldovich effect selected cluster candidates.Comment: 11 pages, 4 figures. Proceedings of Precision Astronomy with Fully Depleted CCDs Workshop (2014). Accepted for publication in JINS

    See-saw fermion masses in an SO(10) GUT

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    In this work we study an SO(10) GUT model with minimum Higgs representations belonging only to the 210 and 16 dimensional representations of SO(10). We add a singlet fermion S in addition to the usual 16 dimensional representation containing quarks and leptons. There are no Higgs bi-doublets and so charged fermion masses come from one-loop corrections. Consequently all the fermion masses, Dirac and Majorana, are of the see-saw type. We minimize the Higgs potential and show how the left-right symmetry is broken in our model where it is assumed that a D-parity odd Higgs field gets a vacuum expectation value at the grand unification scale. From the renormalization group equations we infer that in our model unification happens at 10^{15} GeV and left-right symmetry can be extended up to some values just above 10^{11} GeV. The Yukawa sector of our model is completely different from most of the standard grand unified theories and we explicitly show how the Yukawa sector will look like in the different phases and briefly comment on the running of the top quark mass. We end with a brief analysis of lepton number asymmetry generated from the interactions in our model.Comment: 30 pages, 10 figure

    Time Delay Estimation Performance in a Scattering Medium

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    The effects of a scattering medium on the performance of time delay estimation are considered. The medium is assumed to exhibit angular scattering, causing angular (as well as delay) dispersion and hence loss of signal coherence across the array aperture. Both the variance (via the Cramer-Rao bound) and the bias introduced in the time-delay estimates are studied. The results have been converted to bearing and range error standard deviation and bias. It is found from these studies that there is an optimum range of values for the separation distance between the sensors in the design of an array for time delay estimation, for range and bearing measurements

    Quantitative modeling of \textit{in situ} x-ray reflectivity during organic molecule thin film growth

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    Synchrotron-based x-ray reflectivity is increasingly employed as an \textit{in situ} probe of surface morphology during thin film growth, but complete interpretation of the results requires modeling the growth process. Many models have been developed and employed for this purpose, yet no detailed, comparative studies of their scope and accuracy exists in the literature. Using experimental data obtained from hyperthermal deposition of pentane and diindenoperylene (DIP) on SiO2_2, we compare and contrast three such models, both with each other and with detailed characterization of the surface morphology using ex-situ atomic force microscopy (AFM). These two systems each exhibit particular phenomena of broader interest: pentacene/SiO2_2 exhibits a rapid transition from rough to smooth growth. DIP/SiO2_2, under the conditions employed here, exhibits growth rate acceleration due to a different sticking probability between the substrate and film. In general, \textit{independent of which model is used}, we find good agreement between the surface morphology obtained from fits to the \insitu x-ray data with the actual morphology at early times. This agreement deteriorates at later time, once the root-mean squared (rms) film roughness exceeds about 1 ML. A second observation is that, because layer coverages are under-determined by the evolution of a single point on the reflectivity curve, we find that the best fits to reflectivity data --- corresponding to the lowest values of χν2\chi_\nu^2 --- do not necessarily yield the best agreement between simulated and measured surface morphologies. Instead, it appears critical that the model reproduce all local extrema in the data. In addition to showing that layer morphologies can be extracted from a minimal set of data, the methodology established here provides a basis for improving models of multilayer growth by comparison to real systems.Comment: 34 pages (double-spaced, including figures and references), 10 figures, 3 appendice

    Stellar Mass to Halo Mass Scaling Relation for X-ray Selected Low Mass Galaxy Clusters and Groups out to Redshift z1z\approx1

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    We present the stellar mass-halo mass scaling relation for 46 X-ray selected low-mass clusters or groups detected in the XMM-BCS survey with masses 2×1013MM5002.5×1014M2\times10^{13}M_{\odot}\lesssim M_{500}\lesssim2.5\times10^{14}M_{\odot} at redshift 0.1z1.020.1\le z \le1.02. The cluster binding masses M500M_{500} are inferred from the measured X-ray luminosities \Lx, while the stellar masses MM_{\star} of the galaxy populations are estimated using near-infrared imaging from the SSDF survey and optical imaging from the BCS survey. With the measured \Lx\ and stellar mass MM_{\star}, we determine the best fit stellar mass-halo mass relation, accounting for selection effects, measurement uncertainties and the intrinsic scatter in the scaling relation. The resulting mass trend is MM5000.69±0.15M_{\star}\propto M_{500}^{0.69\pm0.15}, the intrinsic (log-normal) scatter is σlnMM500=0.360.06+0.07\sigma_{\ln M_{\star}|M_{500}}=0.36^{+0.07}_{-0.06}, and there is no significant redshift trend M(1+z)0.04±0.47M_{\star}\propto (1+z)^{-0.04\pm0.47}, although the uncertainties are still large. We also examine MM_{\star} within a fixed projected radius of 0.50.5~Mpc, showing that it provides a cluster binding mass proxy with intrinsic scatter of 93%\approx93\% (1σ\sigma in M500M_{500}). We compare our M=M(M500,z)M_{\star}=M_{\star}(M_{500}, z) scaling relation from the XMM-BCS clusters with samples of massive, SZE-selected clusters (M5006×1014MM_{500}\approx6\times10^{14}M_{\odot}) and low mass NIR-selected clusters (M5001014MM_{500}\approx10^{14}M_{\odot}) at redshift 0.6z1.30.6\lesssim z \lesssim1.3. After correcting for the known mass measurement systematics in the compared samples, we find that the scaling relation is in good agreement with the high redshift samples, suggesting that for both groups and clusters the stellar content of the galaxy populations within R500R_{500} depends strongly on mass but only weakly on redshift out to z1z\approx1.Comment: 15 pages, 10 figures. Accepted for publication in MNRA

    The politics of open defecation: informality, body, and infrastructure in Mumbai

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    This paper examines the politics of open defecation by focusing on everyday intersections of the body and infrastructure in the metabolic city, which produces profoundly unequal opportunities for fulfilling bodily needs. Specifically, it examines how open defecation emerges in Mumbai's informal settlements through everyday embodied experiences, practices and perceptions forged in relation to the materialities of informality and infrastructure. It does so by tracing the micropolitics of provision, access, territoriality and control of sanitation infrastructures; everyday routines and rhythms, both of people and infrastructures; and experiences of disgust and perceptions of dignity. It also examines open defecation as embodied spatial and temporal improvisations in order to investigate the socially differentiated efforts and risks that it entails. More broadly, the paper seeks to deepen understandings of the relationship between the body, infrastructure and the sanitary/unsanitary city

    Complex networks generated by the Penna bit-string model: emergence of small-world and assortative mixing

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    The Penna bit-string model successfully encompasses many phenomena of population evolution, including inheritance, mutation, evolution, and aging. If we consider social interactions among individuals in the Penna model, the population will form a complex network. In this paper, we first modify the Verhulst factor to control only the birth rate, and introduce activity-based preferential reproduction of offspring in the Penna model. The social interactions among individuals are generated by both inheritance and activity-based preferential increase. Then we study the properties of the complex network generated by the modified Penna model. We find that the resulting complex network has a small-world effect and the assortative mixing property
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