1,735 research outputs found
Variation in Insurance Coverage Across Congressional Districts: New Estimates From 2008
Examines trends in rates of private health insurance coverage, public coverage, and uninsurance by congressional district and poverty rate. Identifies districts that have the most to gain from health reforms designed to increase coverage
Investigations on Dynamical Stability in 3D Quadrupole Ion Traps
We firstly discuss classical stability for a dynamical system of two ions levitated in a 3D Radio-Frequency (RF) trap, assimilated with two coupled oscillators. We obtain the solutions of the coupled system of equations that characterizes the associated dynamics. In addition, we supply the modes of oscillation and demonstrate the weak coupling condition is inappropriate in practice, while for collective modes of motion (and strong coupling) only a peak of the mass can be detected. Phase portraits and power spectra are employed to illustrate how the trajectory executes quasiperiodic motion on the surface of torus, namely a Kolmogorov–Arnold–Moser (KAM) torus. In an attempt to better describe dynamical stability of the system, we introduce a model that characterizes dynamical stability and the critical points based on the Hessian matrix approach. The model is then applied to investigate quantum dynamics for many-body systems consisting of identical ions, levitated in 2D and 3D ion traps. Finally, the same model is applied to the case of a combined 3D Quadrupole Ion Trap (QIT) with axial symmetry, for which we obtain the associated Hamilton function. The ion distribution can be described by means of numerical modeling, based on the Hamilton function we assign to the system. The approach we introduce is effective to infer the parameters of distinct types of traps by applying a unitary and coherent method, and especially for identifying equilibrium configurations, of large interest for ion crystals or quantum logic
Separation of natural from laboratory-grown diamond using time-gated luminescence imaging
A technique that expands on the surface luminescence imaging used in the DiamondView instrument has been developed at De Beers Group Technology, Maidenhead, UK. This provides an additional level of imaging information by way of separating prompt and delayed surface luminescence. The technique has the added benefit of quickly and easily distinguishing colorless or near-colorless natural diamond from laboratory-grown diamond. It can be applied when the identification of natural diamond is required in the study of single stones, multiples in batches, set jewelry, or in a fully automated process. The prompt and delayed luminescence characteristics of natural diamond are compared with a range of chemical vapor deposition (CVD) and high-pressure, high-temperature (HPHT) synthetic diamonds. Of significant interest are some of the less common CVD synthetic samples that have been observed in recent years. This article will summarize the luminescence observed in different diamond types, discuss its spectral characteristics, and serve as a useful reference when interpreting such luminescence images
Real-time tomography mooring
A real-time tomography system has been developed which combines ocean acoustic tomography with satellite-based time keeping
and satellite telemetry. The basis of the system is the acoustic tomography transceiver and its associated acoustic navigation grid.
To this basic system, a link to the surface has been added to provide a pathway for telemetry of the tomographic data to shore and a downlink for satellite-derived time which is used to correct the transceiver's clock. The surface buoy contains a GPS receiver, clock comparator, system controller and multiple ID Argos transmitters. Processed tomography signals, transceiver location data time, time drift and surface buoy engineering data are transmitted to satellite using a total of 32 data buffers transmitted every eight minutes. The report describes the real-time tomography system in detail, with particular emphasis on the modifications
implemented to convert the standard tomography instrument to a real-time oceanographic tool.Funding was provided by the Office of Naval Technology
under Contract No. N000-14-C-90-0098
Inter‐ and intra‐software reproducibility of computed tomography lung density measurements
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156221/2/mp14130.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156221/1/mp14130_am.pd
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Estuarine Processes and Their Stratigraphic Record: Paleosalinity and Sedimentation Changes in the Hudson Estuary (North America)
Paleosalinity estimates and rates of sedimentation inferred from core samples from the Hudson estuary for the interval between 6.4 and 1.3 ka indicate a possible role for the estuarine turbidity maximum (ETM) in influencing patterns of estuarine sedimentation at centennial to millennial time scales. Currently in the estuary, sedimentation is localized via sediment trapping particularly in the vicinity of the ETM, 13–26 km upstream from Battery Park (FBP) at the southern tip of Manhattan, in water depths greater than 4 m, and on the western side of the estuary. Data presented in this paper are from cores located within the segment of the estuary 29–50 km FBP. Age constraints are provided by C-14 dating. Paleoenvironmental interpretations are based upon paleosalinity estimates, grain size variability, and sedimentary structures.
Paleosalinity was inferred on the basis of foraminiferal biofacies analysis and a new method for estimating summertime paleosalinity using oxygen isotope measurements in bivalve shell material. The isotopic analysis of a narrow size fraction (1.0–1.7 mm) representing summer growth of a single bivalve species (Gemma gemma) reduces the uncertainty related to annual changes in temperature. Data from ∼45 km FBP indicate a gradual decrease in summertime paleosalinity between 6.4 and 2.0 ka from 25–20‰ to 15–10‰ (the latter is similar to present-day values). These results are consistent with the conclusion of an earlier low-resolution study.
Sedimentation rates are generally low and are similar to the rate of sea-level rise in the Hudson River. Lowest sedimentation rates are noted in short (lower than 2 m) cores from north of the Tappan Zee Bridge (40–50 km FBP from 2.4 ka to present); in shallow water (∼2 m at mean low water, core SD-11) ∼45 km FBP; and on the eastern side of the estuary from ∼50 to 29 km FBP. Exceptions are high sedimentation rates (up to four times background) observed in cores from the western flats (SD 30, ∼45 km FBP, 4.9 to 3.4 ka) in water depths of 4 m and from the western part of the main channel (P21.7 core, ∼32 km FBP, greater than 2.3 to ∼1.3 ka).
We hypothesize that the observed pattern in sediment accumulation relates to a location for the ETM some 20 km upstream of its present position at 3 ka. Downstream migration of the ETM since 3 ka is ascribed to shoaling of the estuary, effectively squeezing the marine saltwater wedge in the same direction, and off marginal flats into the channel. Such shoaling would have enhanced the role of waves in mixing marine and fresher surface water, and reduced the effect of the ETM in focusing sediment accumulation. The results of this study are consistent with the idea that at any time, estuarine sedimentation is highly localized, suggesting a more complex depositional pattern than previously indicated in estuarine stratigraphic models
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The Structure Of (+/-)-21-Oxoisopteropodine
Methyl (1'S*,3S*,4a'S*,5a'S*,10a'R*)-3',4a',5a',6',7',8',10',10a'-octahydro-2-hydroxy-1'-methyl-10'-oxospiro[3H-indole-3,6'-[1'H]pyrano[3,4-f]indolizine-4'-carboxylate, (1), C21H22N2O5, M(r) = 382.42, monoclinic, P2(1)/c, a = 12.920 (4), b = 10.342 (4), c = 15.192 (8) angstrom, beta = 105.68 (3)degrees, V = 1954.4 (14) angstrom 3, Z = 4, D(x) = 1.30 g cm-3 (298 K), mu = 0.8738 cm-1, Mo K-alpha radiation, lambda = 0.7107 angstrom, F(000) = 808, T = 298 K, R = 0.0800 for 1000 reflections, F(o) greater-than-or-equal-to 4-sigma(F(o)). The indole NH group is hydrogen bonded to the amide oxygen, O15' (related by x, 0.5 -y, -0.5 + z), of the indolizine moiety with relevant parameters: N...O 2.79 (2) angstrom, H...O 2.02 (15) angstrom, N-H...O 145 (14)degrees. A close, non-bonded contact of 2.28 (8) angstrom is also observed between O15' and H7' A (related by - x, 0.5 + y, 1.5 - z).Robert A. Welch FoundationNational Institutes of Health (GM 25439)Chemistr
Deferiprone modulates in vitro responses by peripheral blood T cells from control and relapsing remitting multiple sclerosis subjects
T cells are important mediators of autoimmune inflammation in relapsing remitting multiple sclerosis (RRMS). Previous studies found that deferiprone, an iron chelator, suppressed disease activity in a mouse model of multiple sclerosis, and inhibition of T cell proliferation was implicated as a putative mechanism. The objective of the present study was to examine the effects of deferiprone on suppressing in vitro responses of T cells from control and RRMS subjects. Peripheral blood T cells were co-stimulated with anti-CD3 + anti-CD28 and cultured with or without interleukin 2 (IL-2). Proliferating CD4+ T cells from control and RRMS subjects, cultured with or without IL-2, decreased in response to 75 μM deferiprone, although the extent of decreased proliferation of CD4+ T cells from RRMS subjects was less than for control subjects. Proliferating CD8+ T cells from control subjects, cultured with or without IL-2, also decreased in response to 75 μM deferiprone, and this decrease was seen in proliferating CD8+ T cells from RRMS cultured with IL-2. CD4+CD25+ and CD8+CD25+ cells from control subjects, cultured with or without IL-2, declined in 75 M deferiprone, but the decrease was smaller than for the CD4+ and CD8+ proliferative responses. CD4+CD25+ and CD8+CD25+ cells from RRMS subjects showed more variability than for control subjects, but CD4+CD25+ cultured with IL-2 and CD8+CD25+ cells cultured without IL-2 significantly declined in 75 μM deferiprone. CD4+FoxP3+ and CD4+CD25+FoxP3+ cells tended to remain constant or increase. In summary, deferiprone induced declines in proliferative responses at a dosage that is within peak serum pharmacological concentrations
Inferring gene coexpression networks for low dose ionizing radiation using graph theoretical algorithms and systems genetics
Background
Biological data generated through large scale -omics technologies have resulted in a new paradigm in the study of biological systems. Instead of focusing on individual genes or proteins these technologies enable us to extract biological networks using powerful computing and statistical algorithms that are scalable to very large datasets.
Materials and methods
We have developed a tool chain using novel graph algorithms to extract gene coexpression networks from microarray data. We highlight implementation of our tool chain to investigate the effects of in vivo low dose ionizing radiation treatments on mice. We are using systems genetics approach to investigate the biological effects of low dose (10 cGy) ionizing radiation. We measured the base line gene expression profile from spleen tissue of BXD recombinant inbred mice using Illumina microarrays. The data was filtered using coefficient of variance after robust spline normalization and variance stabilizing transformation. A graph was then derived from this data, with probes as vertices and edges between them representing correlations. The graph was analyzed using our toolkit to find the size and number of maximal cliques. We deployed another tool called paraclique that relaxes clique’s requirement that every edge be present between all vertices. Paraclique enables us to account for inherent noise in the microarray data and stochastic nature of biological processes. Using immunophenotype data from the baseline BXD mice, we employed biclique analysis to determine interactions between genotypes and immunophenotypes (%CD4, %CD3, LN T:B, %CD8, and LN CD4:CD8). We also extracted eQTLs from BXD data using QTL-Reaper from base line gene expression profiles. 1881 transcripts were associated with 686 loci. The eQTLs were classified as cis or trans according to their genomic positions. Besides population level studies we also investigated the differential effect of low dose and high dose (1Gy) of ionizing radiations on spleen gene expression in inbred parental strains (C57BL/6J and DBA/2J) of BXD recombinant inbred mice as well as BALB/c mice, a known radiation-sensitive strain
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