474 research outputs found
Development and applications of optical interferometric micrometrology in the angstrom and subangstrom range
The recent development of the scanning electron tunneling microscope and the atomic force microscope requires absolute standards for measurements in the angstrom and subangstrom range. Optical interferometry with lasers and multiple mode laser resonances can provide absolute measurements as the laser wavelengths are very accurately known. A key feature of such measurements is the use of piezoelectric crystals as translators of the highest accuracy for very small disturbances. However, the dimensional changes of these crystals resulting from electrical potential changes depend on many variables, among them the method of mounting, so that accurate calibrations are necessary. Starting from advances in optical metrology made by physicists trying to find gravity waves, advances which led to measurements down to 10 to the -5 A, the author designed and built a much simpler system for the angstrom range. The major limiting factors were mechanical vibrations, air currents, thermal changes and laser instabilities
Iron mineralogy of a Hawaiian palagonitic soil with Mars-like spectral and magnetic properties
Visible and near-IR spectral data for some palagonitic soils from Mauna Kea, Hawaii, are similar to corresponding spectral data for Mars. It is important to understand the composition, distribution, and mineralogy of the ferric-bearing phases for the best spectral analogues because the correspondence in spectral properties implies that the nature of their ferric-bearing phases may be similar to those on Mars. In order to constrain interpretations of the Martian data, a variety of palagonitic soils should be studied in order to establish to what extent differences in their spectral data correspond to differences in the mineralogy of their ferric-bearing phases. Spectral (350-2100 nm), Mossbauer, magnetic, and some compositional data for one of a suite of Hawaiian palagonitic soils are presented. The soil (HWMK1) was collected below the biologically active zone from the sides of a gully cut at 9000 ft elevation on Mauna Kea. The soil was wet sieved with freon into seven size fractions less than 1 mm
Modeling Concurrency in Parallel Debugging
We propose a description language, Data Path Expressions (DPEs), for modeling the behavior of parallel programs. We have designed DPEs as a high-level debugging language, where the debugging paradigm is for the programmer to describe the expected program behavior and for the debugger to compare the actual program behavior during execution to detect program errors. We classify DPEs into five subclasses according to syntactic criteria, and characterize their semantics in terms of a hierarchy of extended Petri Net models. The characterization demonstrates the power of DPEs for modeling (true) concurrency. We also present predecessor automata as a mechanism for implementing the third subclass of DPEs, which expresses bounded parallelism. Predecessor automata extend finite state automata to recognize or generate partial ordering graphs as well as strings, and provide efficient event recognizers for parallel debugging. We briefly describe the application of DPEs race conditions, deadlock and starvation
Hypoxia drives glucose transporter 3 expression through HIF-mediated induction of the long non-coding RNA NICI
Hypoxia inducible transcription factors (HIFs) directly dictate the expression of multiple RNA species including novel and as yet uncharacterized long non-coding transcripts with unknown function. We used pan-genomic HIF-binding and transcriptomic data to identify a novel long non-coding RNA NICI (Non-coding Intergenic Co-Induced transcript) on chromosome 12p13.31 which is regulated by hypoxia via HIF-1 promoter-binding in multiple cell types. CRISPR/Cas9-mediated deletion of the hypoxia-response element revealed co-regulation of NICI and the neighboring protein-coding gene, solute carrier family 2 member 3 (SLC2A3) which encodes the high-affinity glucose transporter 3 (GLUT3). Knock-down or knock-out of NICI attenuated hypoxic induction of SLC2A3 indicating a direct regulatory role of NICI in SLC2A3 expression, which was further evidenced by CRISPR/Cas9-VPR mediated activation of NICI expression. We also demonstrate that regulation of SLC2A3 is mediated through transcriptional activation rather than post-transcriptional mechanisms since knock-out of NICI leads to reduced recruitment of RNA polymerase 2 to the SLC2A3 promoter. Consistent with this we observe NICI-dependent regulation of glucose consumption and cell proliferation. Furthermore, NICI expression is regulated by the VHL tumour suppressor and is highly expressed in clear cell renal cancer, where SLC2A3 expression is associated with patient prognosis, implying an important role for the HIF/NICI/SLC2A3 axis in this malignancy
Future Directions for Cardiovascular Disease Comparative Effectiveness Research Report of a Workshop Sponsored by the National Heart, Lung, and Blood Institute
Comparative effectiveness research (CER) aims to provide decision makers with the evidence needed to evaluate the benefits and harms of alternative clinical management strategies. CER has become a national priority, with considerable new research funding allocated. Cardiovascular disease is a priority area for CER. This workshop report provides an overview of CER methods, with an emphasis on practical clinical trials and observational treatment comparisons. The report also details recommendations to the National Heart, Lung, and Blood Institute for a new framework for evidence development to foster cardiovascular CER, and specific studies to address 8 clinical issues identified by the Institute of Medicine as high priorities for cardiovascular CER
Flying Squirrel–associated Typhus, United States
In March 2002, typhus fever was diagnosed in two patients residing in West Virginia and Georgia. Both patients were hospitalized with severe febrile illnesses, and both had been recently exposed to or had physical contact with flying squirrels or flying squirrel nests. Laboratory results indicated Rickettsia prowazekii infection
A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?
Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t_2 > 10 d converge to nearly the same absolute magnitude about two weeks after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t_2 > 10 d we find that M87 novae display M_(606W,15) = −6.37 ± 0.46 and M_(814W,15) = −6.11 ± 0.43. If very fast novae with decline times t_2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 per cent with the above calibrations
The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III
The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with
new instrumentation and new surveys focused on Galactic structure and chemical
evolution, measurements of the baryon oscillation feature in the clustering of
galaxies and the quasar Ly alpha forest, and a radial velocity search for
planets around ~8000 stars. This paper describes the first data release of
SDSS-III (and the eighth counting from the beginning of the SDSS). The release
includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap,
bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a
third of the Celestial Sphere. All the imaging data have been reprocessed with
an improved sky-subtraction algorithm and a final, self-consistent photometric
recalibration and flat-field determination. This release also includes all data
from the second phase of the Sloan Extension for Galactic Understanding and
Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars
at both high and low Galactic latitudes. All the more than half a million
stellar spectra obtained with the SDSS spectrograph have been reprocessed
through an improved stellar parameters pipeline, which has better determination
of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from
submitted version
A prospective, randomized clinical trial of antiretroviral therapies on carotid wall thickness
Objective: This article compares the effects of initiating three contemporary antiretroviral therapy (ART) regimens on progression of carotid artery intima-media thickness (IMT) over 3 years. Design: Randomized clinical trial. Setting: Multicenter (26 institutions). Patients: ART-naive HIV-infected individuals (n ¼ 328) without known cardiovascular disease or diabetes mellitus. Intervention: Random assignment to tenofovir/emtricitabine along with atazanavir/ ritonavir (ATV/r), darunavir/ritonavir (DRV/r), or raltegravir (RAL). Main outcome measures: Right-sided carotid IMT was evaluated by B-mode ultrasonography before ART initiation, and then after 48, 96, and 144 weeks. Comparisons of yearly rates of change in carotid IMT used mixed-effects linear regression models that permitted not only evaluation of the effects of ART on carotid IMT progression but also how ART-associated changes in traditional risk factors, bilirubin, and markers of HIV infection were associated carotid IMT progression. Results: HIV-1 RNA suppression rates were high in all arms (>85%) over 144 weeks. Modest increases in triglycerides and non-high-density lipoprotein cholesterol levels were observed in the protease inhibitor-containing arms compared with decreases with RAL. In contrast, carotid IMT progressed more slowly on ATV/r [8.2, 95% confidence interval (5.6, 10.8) mm/year] than DRV/r [12.9 (10.3, 15.5) mm/year, P ¼ 0.013]; changes with RAL were intermediate [10.7 (9.2, 12.2) mm/year, P ¼ 0.15 vs. ATV/r; P ¼ 0.31 vs. DRV/r]. Bilirubin and non-high-density lipoprotein cholesterol levels appeared to influence carotid IMT progression rates. Conclusion: In ART-naive HIV-infected individuals at low cardiovascular disease risk, carotid IMT progressed more slowly in participants initiating ATV/r than those initiating DRV/r, with intermediate changes associated with RAL. This effect may be due, in part, to hyperbilirubinemia
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