249 research outputs found
Weighted Least-Squares Finite Element Method for Cardiac Blood Flow Simulation with Echocardiographic Data
As both fluid flow measurement techniques and computer simulation methods continue to improve, there is a growing need for numerical simulation approaches that can assimilate experimental data into the simulation in a flexible and mathematically consistent manner. The problem of interest here is the simulation of blood flow in the left ventricle with the assimilation of experimental data provided by ultrasound imaging of microbubbles in the blood. The weighted least-squares finite element method is used because it allows data to be assimilated in a very flexible manner so that accurate measurements are more closely matched with the numerical solution than less accurate data. This approach is applied to two different test problems: a flexible flap that is displaced by a jet of fluid and blood flow in the porcine left ventricle. By adjusting how closely the simulation matches the experimental data, one can observe potential inaccuracies in the model because the simulation without experimental data differs significantly from the simulation with the data. Additionally, the assimilation of experimental data can help the simulation capture certain small effects that are present in the experiment, but not modeled directly in the simulation
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The characteristics of cognitive neuroscience tests in a schizophrenia cognition clinical trial: Psychometric properties and correlations with standard measures.
In comparison to batteries of standard neuropsychological tests, cognitive neuroscience tests may offer a more specific assessment of discrete neurobiological processes that may be aberrant in schizophrenia. However, more information regarding psychometric properties and correlations with standard neuropsychological tests and functional measures is warranted to establish their validity as treatment outcome measures. The N-back and AX-Continuous Performance Task (AX-CPT) are two promising cognitive neuroscience tests designed to measure specific components of working memory and contextual processing respectively. In the current study, we report the psychometric properties of multiple outcome measures from these two tests as well as their correlations with standard neuropsychological measures and functional capacity measures. The results suggest that while the AX-CPT and N-back display favorable psychometric properties, they do not exhibit greater sensitivity or specificity with functional measures than standard neurocognitive tests
Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER
We describe 280 GHz bolometric detector arrays that instrument the
balloon-borne polarimeter SPIDER. A primary science goal of SPIDER is to
measure the large-scale B-mode polarization of the cosmic microwave background
in search of the cosmic-inflation, gravitational-wave signature. 280 GHz
channels aid this science goal by constraining the level of B-mode
contamination from galactic dust emission. We present the focal plane unit
design, which consists of a 1616 array of conical, corrugated feedhorns
coupled to a monolithic detector array fabricated on a 150 mm diameter silicon
wafer. Detector arrays are capable of polarimetric sensing via waveguide
probe-coupling to a multiplexed array of transition-edge-sensor (TES)
bolometers. The SPIDER receiver has three focal plane units at 280 GHz, which
in total contains 765 spatial pixels and 1,530 polarization sensitive
bolometers. By fabrication and measurement of single feedhorns, we demonstrate
14.7 FHWM Gaussian-shaped beams with 1% ellipticity in a 30%
fractional bandwidth centered at 280 GHz. We present electromagnetic
simulations of the detection circuit, which show 94% band-averaged,
single-polarization coupling efficiency, 3% reflection and 3% radiative loss.
Lastly, we demonstrate a low thermal conductance bolometer, which is
well-described by a simple TES model and exhibits an electrical noise
equivalent power (NEP) = 2.6 10 W/,
consistent with the phonon noise prediction.Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 201
CMB-S4 Science Book, First Edition
This book lays out the scientific goals to be addressed by the
next-generation ground-based cosmic microwave background experiment, CMB-S4,
envisioned to consist of dedicated telescopes at the South Pole, the high
Chilean Atacama plateau and possibly a northern hemisphere site, all equipped
with new superconducting cameras. CMB-S4 will dramatically advance cosmological
studies by crossing critical thresholds in the search for the B-mode
polarization signature of primordial gravitational waves, in the determination
of the number and masses of the neutrinos, in the search for evidence of new
light relics, in constraining the nature of dark energy, and in testing general
relativity on large scales
Treatment with indinavir, zidovudine, and lamivudine in adults with human immunodeficiency virus infection and prior antiretroviral therapy
Background: The new protease inhibitors are potent
inhibitors of the human immunodeficiency virus
(HIV), and in combination with other antiretroviral
drugs they may be able to cause profound and sustained
suppression of HIV replication.
Methods: In this double-blind study, 97 HIV-infected
patients who had received zidovudine treatment
for at least 6 months and had 50 to 400 CD4 cells per
cubic millimeter and at least 20,000 copies of HIV
RNA per milliliter were randomly assigned to one of
three treatments for up to 52 weeks: 800 mg of indinavir
every eight hours; 200 mg of zidovudine every
eight hours combined with 150 mg of lamivudine
twice daily; or all three drugs. The patients were followed
to monitor the occurrence of adverse events
and changes in viral load and CD4 cell counts.
Results: The decrease in HIV RNA over the first 24
weeks was greater in the three-drug group than in
the other groups (P�0.001 for each comparison).
RNA levels decreased to less than 500 copies per
milliliter at week 24 in 28 of 31 patients in the threedrug
group (90 percent), 12 of 28 patients in the indinavir
group (43 percent), and none of 30 patients
in the zidovudine–lamivudine group. The increase in
CD4 cell counts over the first 24 weeks was greater
in the two groups receiving indinavir than in the zidovudine–
lamivudine group (P<0.01 for each comparison).
The changes in the viral load and the CD4
cell count persisted for up to 52 weeks. All the regimens
were generally well tolerated.
Conclusions: In most HIV-infected patients with
prior antiretroviral therapy, the combination of indinavir,
zidovudine, and lamivudine reduces levels of
HIV RNA to less than 500 copies per milliliter for as
long as one year. (N Engl J Med 1997;337:734-9.
The Cosmology Large Angular Scale Surveyor Receiver Design
The Cosmology Large Angular Scale Surveyor consists of four instruments
performing a CMB polarization survey. Currently, the 40 GHz and first 90 GHz
instruments are deployed and observing, with the second 90 GHz and a
multichroic 150/220 GHz instrument to follow. The receiver is a central
component of each instrument's design and functionality. This paper describes
the CLASS receiver design, using the first 90 GHz receiver as a primary
reference. Cryogenic cooling and filters maintain a cold, low-noise environment
for the detectors. We have achieved receiver detector temperatures below 50 mK
in the 40 GHz instrument for 85% of the initial 1.5 years of operation, and
observed in-band efficiency that is consistent with pre-deployment estimates.
At 90 GHz, less than 26% of in-band power is lost to the filters and lenses in
the receiver, allowing for high optical efficiency. We discuss the mounting
scheme for the filters and lenses, the alignment of the cold optics and
detectors, stray light control, and magnetic shielding.Comment: Fixed formatting of abstract; 20 Pages, 11 Figures, SPIE Conference
Proceeding
Report of the State Bar of Arizona Corporate, Banking, and Business Law Section Subcommittee on Rendering Legal Opinions in Business Transactions, February 1, 1989
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