1,812 research outputs found
Design Optimization for Solar Array of Multiple Collector Types
Methodology is presented for optimizing solar arrays used for heating fluids from ambient to elevated temperatures. The optimal array consists of the appropriate combination of available collector types which delivers the most energy per dollar invested in the array. An example optimization is presented and verified using computer simulation of numerous combinations of collector types
Dynamical trapping and relaxation of scalar gravitational fields
We present a framework for nonlinearly coupled scalar-tensor theory of
gravity to address both inflation and core-collapse supernova problems. The
unified approach is based on a novel dynamical trapping and relaxation of
scalar gravity in highly energetic regimes. The new model provides a viable
alternative mechanism of inflation free from various issues known to affect
previous proposals. Furthermore, it could be related to observable violent
astronomical events, specifically by releasing a significant amount of
additional gravitational energy during core-collapse supernovae. A recent
experiment at CERN relevant for testing this new model is briefly outlined.Comment: 4 pages; version to appear in PL
Antibody response to pneumococcal and influenza vaccination in patients with rheumatoid arthritis receiving abatacept
Background Patients with rheumatoid arthritis (RA), including those treated
with biologics, are at increased risk of some vaccine-preventable infections.
We evaluated the antibody response to standard 23-valent pneumococcal
polysaccharide vaccine (PPSV23) and the 2011â2012 trivalent seasonal influenza
vaccine in adults with RA receiving subcutaneous (SC) abatacept and background
disease-modifying anti-rheumatic drugs (DMARDs). Methods Two multicenter,
open-label sub-studies enrolled patients from the ACQUIRE (pneumococcal and
influenza) and ATTUNE (pneumococcal) studies at any point during their SC
abatacept treatment cycle following completion of â„3 monthsâ SC abatacept. All
patients received fixed-dose abatacept 125 mg/week with background DMARDs. A
pre-vaccination blood sample was taken, and after 28â±â3 days a final post-
vaccination sample was collected. The primary endpoint was the proportion of
patients achieving an immunologic response to the vaccine at Day 28 among
patients without a protective antibody level to the vaccine antigens at
baseline (pneumococcal: defined as â„2-fold increase in post-vaccination titers
to â„3 of 5 antigens and protective antibody level of â„1.6 ÎŒg/mL to â„3 of 5
antigens; influenza: defined as â„4-fold increase in post-vaccination titers to
â„2 of 3 antigens and protective antibody level of â„1:40 to â„2 of 3 antigens).
Safety and tolerability were evaluated throughout the sub-studies. Results
Pre- and post-vaccination titers were available for 113/125 and 186/191
enrolled patients receiving the PPSV23 and influenza vaccine, respectively.
Among vaccinated patients, 47/113 pneumococcal and 121/186 influenza patients
were without protective antibody levels at baseline. Among patients with
available data, 73.9 % (34/46) and 61.3 % (73/119) met the primary endpoint
and achieved an immunologic response to PPSV23 or influenza vaccine,
respectively. In patients with pre- and post-vaccination data available, 83.9
% in the pneumococcal study demonstrated protective antibody levels with
PPSV23 (titer â„1.6 ÎŒg/mL to â„3 of 5 antigens), and 81.2 % in the influenza
study achieved protective antibody levels (titer â„1:40 to â„2 of 3 antigens) at
Day 28 post-vaccination. Vaccines were well tolerated with SC abatacept with
background DMARDs. Conclusions In these sub-studies, patients with RA
receiving SC abatacept and background DMARDs were able to mount an appropriate
immune response to pneumococcal and influenza vaccines. Trial registration
NCT00559585 (registered 15 November 2007) and NCT00663702 (registered 18 April
2008)
Inverse problem for wave equation with sources and observations on disjoint sets
We consider an inverse problem for a hyperbolic partial differential equation
on a compact Riemannian manifold. Assuming that and are
two disjoint open subsets of the boundary of the manifold we define the
restricted Dirichlet-to-Neumann operator . This
operator corresponds the boundary measurements when we have smooth sources
supported on and the fields produced by these sources are observed
on . We show that when and are disjoint but
their closures intersect at least at one point, then the restricted
Dirichlet-to-Neumann operator determines the
Riemannian manifold and the metric on it up to an isometry. In the Euclidian
space, the result yields that an anisotropic wave speed inside a compact body
is determined, up to a natural coordinate transformations, by measurements on
the boundary of the body even when wave sources are kept away from receivers.
Moreover, we show that if we have three arbitrary non-empty open subsets
, and of the boundary, then the restricted
Dirichlet-to-Neumann operators for determine the Riemannian manifold to an isometry. Similar result is proven
also for the finite-time boundary measurements when the hyperbolic equation
satisfies an exact controllability condition
High-resolution sub-ice-shelf seafloor records of 20th-century ungrounding and retreat of Pine Island Glacier, West Antarctica.
Pine Island Glacier Ice Shelf (PIGIS) has been thinning rapidly over recent decades, resulting in a progressive drawdown of the inland ice and an upstream migration of the grounding line. The resultant ice loss from Pine Island Glacier (PIG) and its neighboring ice streams presently contributes an estimated âŒ10% to global sea level rise, motivating efforts to constrain better the rate of future ice retreat. One route toward gaining a better understanding of the processes required to underpin physically based projections is provided by examining assemblages of landforms and sediment exposed over recent decades by the ongoing ungrounding of PIG. Here we present high-resolution bathymetry and sub-bottom-profiler data acquired by autonomous underwater vehicle (AUV) surveys beneath PIGIS in 2009 and 2014, respectively. We identify landforms and sediments associated with grounded ice flow, proglacial and subglacial sediment transport, overprinting of lightly grounded ice-shelf keels, and stepwise grounding line retreat. The location of a submarine ridge (Jenkins Ridge) coincides with a transition from exposed crystalline bedrock to abundant sediment cover potentially linked to a thick sedimentary basin extending upstream of the modern grounding line. The capability of acquiring high-resolution data from AUV platforms enables observations of landforms and understanding of processes on a scale that is not possible in standard offshore geophysical surveys
Global Brain Dynamics during Social Exclusion Predict Subsequent Behavioral Conformity
Individuals react differently to social experiences; for example, people who are more sensitive to negative social experiences, such as being excluded, may be more likely to adapt their behavior to fit in with others. We examined whether functional brain connectivity during social exclusion in the fMRI scanner can be used to predict subsequent conformity to peer norms. Adolescent males (nâ=â57) completed a two-part study on teen driving risk: a social exclusion task (Cyberball) during an fMRI session and a subsequent driving simulator session in which they drove alone and in the presence of a peer who expressed risk-averse or risk-accepting driving norms. We computed the difference in functional connectivity between social exclusion and social inclusion from each node in the brain to nodes in two brain networks, one previously associated with mentalizing (medial prefrontal cortex, temporoparietal junction, precuneus, temporal poles) and another with social pain (dorsal anterior cingulate cortex, anterior insula). Using predictive modeling, this measure of global connectivity during exclusion predicted the extent of conformity to peer pressure during driving in the subsequent experimental session. These findings extend our understanding of how global neural dynamics guide social behavior, revealing functional network activity that captures individual differences
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Smoking is not linked to the development of anti-peptidylarginine deiminase 4 autoantibodies in rheumatoid arthritis
Background: Defining environmental factors responsible for development of autoimmunity in rheumatoid arthritis (RA) is critical for understanding mechanisms of disease initiation and propagation. Notably, a history of cigarette smoking has been implicated in the genesis of RA and is associated with worse disease outcomes. Antibodies to peptidylarginine deiminase 4 (PAD4) are also associated with more severe RA. A subset of patients who have PAD4 autoantibodies that cross-react with PAD3 (anti-PAD3/4) are at the highest risk for interstitial lung disease, and this risk is augmented by a history of cigarette smoking. It is unclear, however, if smoking is etiologically linked to the development of anti-PAD4 antibodies. Methods: Patients were included in this study if they had physician-diagnosed RA as well as DNA, serum, and a date-matched clinical assessment (n = 274). Anti-PAD4 and anti-CCP antibodies were measured by immunoprecipitation and ELISA, respectively; shared epitope (SE) status was determined by HLA-DRÎČ1 genotyping. Logistic regression analysis was used to evaluate associations of smoking with PAD4 antibodies, with adjustment for relevant demographic and clinical features. Stratified analyses by disease duration and shared epitope status were also performed. Results: Anti-PAD4 antibodies were present in 25% of RA patients, with 50% of these individuals having anti-PAD3/4 cross-reactive antibodies. Anti-PAD4 antibodies were significantly associated with a longer disease duration, SE alleles, and anti-CCP antibodies. Importantly, there were no significant differences in smoking history between anti-PAD4 positive and negative groups in univariate analyses, stratified analyses, or multivariable models. However, an inverse relationship between smoking and anti-PAD4 antibodies was suggested by a lower prevalence of current smokers among patients with anti-PAD3/4 antibodies compared to antibody negative individuals (p = 0.04). Further, the lowest levels of anti-PAD4 antibodies were observed in current smokers (p = 0.14), and a significant association of SE and anti-PAD4 antibodies was only present among never smokers (p = 0.01). Conclusions: Smoking history was not associated with anti-PAD4 antibodies in patients with RA. The finding that anti-PAD4 antibodies were not associated with smoking suggests that other environmental factors may contribute to the development of autoimmunity to PAD4 in these patients
A multi-color and Fourier study of RR Lyrae variables in the globular cluster NGC 5272 (M3)
We have performed a detailed study of the pulsational and evolutionary
characteristics of 133 RR Lyrae stars in the globular cluster NGC5272 (M3)
using highly accurate BVI data taken on 5 separate epochs. M3 seems to contain
no less than ~32% of Blazhko stars, and the occurrence and characteristics of
the Blazhko effect have been analyzed in detail. We have identified a good
number (~ 14%) of overluminous RR Lyrae stars that are likely in a more
advanced evolutionary stage off the Zero Age Horizontal Branch (ZAHB). Physical
parameters (i.e. temperature, luminosity, mass) have been derived from (B--V)
colors and accurate color-temperature calibration, and compared with Horizontal
Branch evolutionary models and with the requirements of stellar pulsation
theory. Additional analysis by means of Fourier decomposition of the V light
curves confirms, as expected, that no metallicity spread is present in M3.
Evolution off the ZAHB does not affect [Fe/H] determinations, whereas Blazhko
stars at low amplitude phase do affect [Fe/H] distributions as they appear more
metal-rich. Absolute magnitudes derived from Fourier coefficients might provide
useful average estimates for groups of stars, if applicable, but do not give
reliable {\em individual} values. Intrinsic colors derived from Fourier
coefficients show significant discrepancies with the observed ones, hence the
resulting temperatures and temperature-related parameters are unreliable.Comment: 86 pages, 19 figures, 13 tables, in press A
Continuum viscoplastic simulation of a granular column collapse on large slopes: Ό(I) rheology and lateral wall effects
We simulate here dry granular flows resulting from the collapse of granular columns on an inclined channel (up to 22°) and compare precisely the results with laboratory experiments. Incompressibility is assumed despite the dilatancy observed in the experiments (up to 10%). The 2-D model is based on the so-called ÎŒ(I) rheology that induces a Drucker-Prager yield stress and a variable viscosity. A nonlinear Coulomb friction term, representing the friction on the lateral walls of the channel, is added to the model. We demonstrate that this term is crucial to accurately reproduce granular collapses on slopes âł10°, whereas it remains of little effect on the horizontal slope. Quantitative comparison between the experimental and numerical changes with time of the thickness profiles and front velocity makes it possible to strongly constrain the rheology. In particular, we show that the use of a variable or a constant viscosity does not change significantly the results provided that these viscosities are of the same order. However, only a fine tuning of the constant viscosity (η=1 Pa s) makes it possible to predict the slow propagation phase observed experimentally at large slopes. Finally, we observed that small-scale instabilities develop when refining the mesh (also called ill-posed behavior, characterized in the work of Barker et al. [âWell-posed and ill-posed behaviour of the ÎŒ(I)-rheology for granular flow,â J. Fluid Mech. 779, 794â818 (2015)] and in the present work) associated with the mechanical model. The velocity field becomes stratified and the bands of high velocity gradient appear. These model instabilities are not avoided by using variable viscosity models such as the ÎŒ(I) rheology. However we show that the velocity range, the static-flowing transition, and the thickness profiles are almost not affected by them
Association of Pain Centralization and PatientâReported Pain in Active Rheumatoid Arthritis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156205/2/acr23994_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156205/1/acr23994.pd
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