38 research outputs found
Binary inspiral, gravitational radiation, and cosmology
Observations of binary inspiral in a single interferometric gravitational
wave detector can be cataloged according to signal-to-noise ratio and
chirp mass . The distribution of events in a catalog composed of
observations with greater than a threshold depends on the
Hubble expansion, deceleration parameter, and cosmological constant, as well as
the distribution of component masses in binary systems and evolutionary
effects. In this paper I find general expressions, valid in any homogeneous and
isotropic cosmological model, for the distribution with and of
cataloged events; I also evaluate these distributions explicitly for relevant
matter-dominated Friedmann-Robertson-Walker models and simple models of the
neutron star mass distribution. In matter dominated Friedmann-Robertson-Walker
cosmological models advanced LIGO detectors will observe binary neutron star
inspiral events with from distances not exceeding approximately
, corresponding to redshifts of (0.26) for
(), at an estimated rate of 1 per week. As the binary system mass
increases so does the distance it can be seen, up to a limit: in a matter
dominated Einstein-deSitter cosmological model with () that limit
is approximately (1.7) for binaries consisting of two
black holes. Cosmological tests based on catalogs of the
kind discussed here depend on the distribution of cataloged events with
and . The distributions found here will play a pivotal role in testing
cosmological models against our own universe and in constructing templates for
the detection of cosmological inspiraling binary neutron stars and black holes.Comment: REVTeX, 38 pages, 9 (encapsulated) postscript figures, uses epsf.st
Observing binary inspiral in gravitational radiation: One interferometer
We investigate the sensitivity of individual LIGO/VIRGO-like interferometers
and the precision with which they can determine the characteristics of an
inspiralling binary system. Since the two interferometers of the LIGO detector
share nearly the same orientation, their joint sensitivity is similar to that
of a single, more sensitive interferometer. We express our results for a single
interferometer of both initial and advanced LIGO design, and also for the LIGO
detector in the limit that its two interferometers share exactly the same
orientation. We approximate the evolution of a binary system as driven
exclusively by leading order quadrupole gravitational radiation. To assess the
sensitivity, we calculate the rate at which sources are expected to be
observed, the range to which they are observable, and the precision with which
characteristic quantities describing the observed binary system can be
determined. Assuming a conservative rate density for coalescing neutron star
binary systems we expect that the advanced LIGO detector will observe
approximately 69~yr with an amplitude SNR greater than 8. Of these,
approximately 7~yr will be from binaries at distances greater than
950~Mpc. We explore the sensitivity of these results to a tunable parameter in
the interferometer design (the recycling frequency). The optimum choice of the
parameter is dependent on the goal of the observations, e.g., maximizing the
rate of detections or maximizing the precision of measurement. We determine the
optimum parameter values for these two cases.Comment: 40 pages (plus 7 figures), LaTeX/REVTEX3.0, NU-GR-
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Noncontact surface thermometry for microsystems: LDRD final report.
We describe a Laboratory Directed Research and Development (LDRD) effort to develop and apply laser-based thermometry diagnostics for obtaining spatially resolved temperature maps on working microelectromechanical systems (MEMS). The goal of the effort was to cultivate diagnostic approaches that could adequately resolve the extremely fine MEMS device features, required no modifications to MEMS device design, and which did not perturb the delicate operation of these extremely small devices. Two optical diagnostics were used in this study: microscale Raman spectroscopy and microscale thermoreflectance. Both methods use a low-energy, nonperturbing probe laser beam, whose arbitrary wavelength can be selected for a diffraction-limited focus that meets the need for micron-scale spatial resolution. Raman is exploited most frequently, as this technique provides a simple and unambiguous measure of the absolute device temperature for most any MEMS semiconductor or insulator material under steady state operation. Temperatures are obtained from the spectral position and width of readily isolated peaks in the measured Raman spectra with a maximum uncertainty near {+-}10 K and a spatial resolution of about 1 micron. Application of the Raman technique is demonstrated for V-shaped and flexure-style polycrystalline silicon electrothermal actuators, and for a GaN high-electron-mobility transistor. The potential of the Raman technique for simultaneous measurement of temperature and in-plane stress in silicon MEMS is also demonstrated and future Raman-variant diagnostics for ultra spatio-temporal resolution probing are discussed. Microscale thermoreflectance has been developed as a complement for the primary Raman diagnostic. Thermoreflectance exploits the small-but-measurable temperature dependence of surface optical reflectivity for diagnostic purposes. The temperature-dependent reflectance behavior of bulk silicon, SUMMiT-V polycrystalline silicon films and metal surfaces is presented. The results for bulk silicon are applied to silicon-on-insulator (SOI) fabricated actuators, where measured temperatures with a maximum uncertainty near {+-}9 K, and 0.75-micron inplane spatial resolution, are achieved for the reflectance-based measurements. Reflectance-based temperatures are found to be in good agreement with Raman-measured temperatures from the same device
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
Relation of Serum Vitamin D to Risk of Mitral Annular and Aortic Valve Calcium (from the Multi-Ethnic Study of Atherosclerosis)
Serum 25-hydroxyvitamin D [25(OH)D] concentration has been identified as a possible modifiable risk factor for cardiovascular disease (CVD). We hypothesized that serum 25(OH)D concentration would be associated with calcifications of the left-sided heart valves, which are markers of CVD risk. Aortic valve calcium (AVC) and mitral annular calcium (MAC) were quantified from cardiac computed tomography scans performed on 5,530 Multi-Ethnic Study of Atherosclerosis participants at the baseline examination (2000 to 2002) and at a follow-up visit at either Examination 2 (2002 to 2004) or Examination 3 (2004 to 2005). 25(OH)D was measured from serum samples collected at the baseline examination. Using relative risk regression, we evaluated the multivariable-adjusted risk of prevalent and incident AVC and MAC in this ethnically diverse population free of clinical CVD at baseline. The mean age of participants was 62 ± 10 years; 53% were women, 40% white, 26% black, 21% Hispanic, and 12% Chinese. Prevalent AVC and MAC were observed in 12% and 9% of study sample, respectively. There were no significant associations between 25(OH)D and prevalent AVC or MAC. Over a mean follow-up of 2.5 years, 4% developed incident AVC and 5% developed incident MAC. After adjusting for demographic variables, each 10 ng/ml higher serum 25(OH)D was associated with a 15% (relative risk 0.85, 95% confidence interval 0.74 to 0.98) lower risk of incident MAC but not AVC. However, this association was no longer significant after adjusting for lifestyle and CVD risk factors. Results suggest a possible link between serum 25(OH)D and the risk for incident MAC, but future studies with longer follow-up are needed to further test this association
Invited Article: Simultaneous mapping of temperature and stress in microdevices using micro-Raman spectroscopy
© 2007 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.2738946DOI: 10.1063/1.2738946Analysis of the Raman Stokes peak position and its shift has been frequently used to estimate either temperature or stress in microelectronics and microelectromechanical system devices. However, if both fields are evolving simultaneously, the Stokes shift represents a convolution of these effects, making it difficult to measure either quantity accurately. By using the relative independence of the Stokes linewidth to applied stress, it is possible to deconvolve the signal into an estimation of both temperature and stress. Using this property, a method is presented whereby the temperature and stress were simultaneously measured in doped polysilicon microheaters. A data collection and analysis method was developed to reduce the uncertainty in the measured stresses resulting in an accuracy of ±40 MPa for an average applied stress of −325 MPa and temperature of 520 °C. Measurement results were compared to three-dimensional finite-element analysis of the microheaters and were shown to be in excellent agreement. This analysis shows that Raman spectroscopy has the potential to measure both evolving temperature and stress fields in devices using a single optical measurement
Recommendations on the measurement and the clinical use of vitamin D metabolites and vitamin D binding protein – A position paper from the IFCC Committee on bone metabolism
Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function. The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other “molecules” related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results
Recommendations on the measurement and theclinical useof vitamin D metabolites and vitamin D binding protein - A position paper from the IFCC Committee on Bone Metabolism.
Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function.The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other "molecules" related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results