3,329 research outputs found

    The roles of kinetic theory and gas-surface interactions in measurements of upper-atmospheric density

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    Kinetic theory and gas-surface interactions in measurements of upper atmospheric densit

    Human Factors Considerations in System Design

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    Human factors considerations in systems design was examined. Human factors in automated command and control, in the efficiency of the human computer interface and system effectiveness are outlined. The following topics are discussed: human factors aspects of control room design; design of interactive systems; human computer dialogue, interaction tasks and techniques; guidelines on ergonomic aspects of control rooms and highly automated environments; system engineering for control by humans; conceptual models of information processing; information display and interaction in real time environments

    Impact of inter-correlated initial binary parameters on double black hole and neutron star mergers

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    The distributions of the initial main-sequence binary parameters are one of the key ingredients in obtaining evolutionary predictions for compact binary (BH-BH / BH-NS / NS-NS) merger rates. Until now, such calculations were done under the assumption that initial binary parameter distributions were independent. Here, we implement empirically derived inter-correlated distributions of initial binary parameters primary mass (M1), mass ratio (q), orbital period (P), and eccentricity (e). Unexpectedly, the introduction of inter-correlated initial binary parameters leads to only a small decrease in the predicted merger rates by a factor of 2 −- 3 relative to the previously used non-correlated initial distributions. The formation of compact object mergers in the isolated classical binary evolution favors initial binaries with stars of comparable masses (q = 0.5 −- 1) at intermediate orbital periods (log P (days) = 2 −- 4). New distributions slightly shift the mass ratios towards smaller values with respect to the previously used flat q distribution, which is the dominant effect decreasing the rates. New orbital periods only negligibly increase the number of progenitors. Additionally, we discuss the uncertainty of merger rate predictions associated with possible variations of the massive-star initial mass function (IMF). We argue that evolutionary calculations should be normalized to a star formation rate (SFR) that is obtained from the observed amount of UV light at wavelength 1500{\AA} (SFR indicator). In this case, contrary to recent reports, the uncertainty of the IMF does not affect the rates by more than a factor of 2. Any change to the IMF slope for massive stars requires a change of SFR in a way that counteracts the impact of IMF variations on the merger rates. In contrast, we suggest that the uncertainty in cosmic SFR at low metallicity can be a significant factor at play.Comment: accepted for publication in A&

    Attorney’s Guide to Montana Conservation Easements

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    Conservation Easement

    Double beta decay of 48^{48}Ca

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    48^{48}Ca, the lightest double beta decay candidate, is the only one simple enough to be treated exactly in the nuclear shell model. Thus, the ββ(2ν)\beta\beta(2\nu) half-life measurement, reported here, provides a unique test of the nuclear physics involved in the ββ\beta\beta matrix element calculation. Enriched 48^{48}Ca sources of two different thicknesses have been exposed in a time projection chamber, and yield T1/22ν=(4.3−1.1+2.4[stat.]±1.4[syst.])×1019_{1/2}^{2\nu} = (4.3^{+2.4}_{-1.1} [{\rm stat.}] \pm 1.4 [{\rm syst.}]) \times 10^{19} years, compatible with the shell model calculations.Comment: 4 pages, LaTex, 3 figures imbedded, PRL forma

    Functional and structural vascular biomarkers in women 1 year after a hypertensive disorder of pregnancy

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    OBJECTIVES: Women with a previous hypertensive disorder of pregnancy (HDP: gestational hypertension and preeclampsia) have increased long-term cardiovascular disease risk. Recent meta-analyses show adverse levels of non-invasive functional and structural cardiovascular risk markers such as pulse wave velocity (PWV), heart-rate adjusted augmentation index (AIx75), carotid intima-media thickness (CIMT), and reactive hyperemia index (RHI) after HDPs, and suggest using these for cardiovascular risk stratification. However, it is not known if a previous HDP predict levels of these markers beyond classical cardiovascular risk factors. Study design and main outcome measures. We assessed PWV, AIx75, CIMT, RHI, classical cardiovascular risk factors, and pregnancy characteristics in 221 women 1 year postpartum (controls: 95, previous HDP: 126). Uni- and multi- variate regression analysis were conducted to assess associations between previous HDP and PWV, AIx75, CIMT or RHI. We adjusted for classical cardiovascular risk factors and pregnancy characteristics. A p-level < 0.05 was considered statistically significant. RESULTS: PWV was associated with previous HDP on univariate analysis. This effect was confounded by blood pressure and not significant after adjustment. We found no significant associations between AIx75, RHI, CIMT, and a previous HDP, neither before nor after adjustments. CONCLUSIONS: Associations between a previous HDP and PWV, AIx75, CIMT, or RHI 1 year postpartum can largely be explained by adverse levels of classical cardiovascular risk markers in women with a previous HDP. Women with previous HDP should receive primary prevention of cardiovascular disease, but PWV, AIx75, CIMT or RHI are unlikely to aid in cardiovascular risk stratification 1 year postpartum

    Nicotinamide treatment in a murine model of familial tumoral calcinosis reduces serum Fgf23 and raises heart calcium

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    Mutations in the GALNT3 gene result in familial tumoral calcinosis, characterized by persistent hyperphosphatemia and ectopic calcific masses in soft tissues. Since calcific masses often recur after surgical removal, a more permanent solution to the problem is required. Nicotinamide is reported to lower serum phosphate by decreasing sodium-dependent phosphate co-transporters in the gut and kidney. However, its effectiveness in tumoral calcinosis remains unknown. In this study, we investigated nicotinamide as a potential therapy for tumoral calcinosis, using a murine model of the disease-Galnt3 knockout mice. Initially, five different doses of nicotinamide were given to normal heterozygous mice intraperitoneally or orally. Treatment had no effect on serum phosphate levels, but serum levels of a phosphaturic hormone, fibroblast growth factor 23 (Fgf23), decreased in a dose-dependent manner. Subsequently, high-dose nicotinamide (40mM) was tested in Galnt3 knockout mice fed a high phosphate diet. The radiographic data pre- and post-treatment showed that nicotinamide did not reverse the calcification. However, the treatment retarded calcification growth after 4weeks, while in the untreated animals, calcifications increased in size. The therapy did not affect serum phosphate levels, but intact Fgf23 decreased in the treated mice. The treated mice also had increased calcium in the heart. In summary, nicotinamide did not alter serum phosphate levels, likely due to compensatory decrease in Fgf23 to counteract the phosphate lowering effect of nicotinamide. Although increased calcium accumulation in the heart is a concern, the therapy appears to slow down the progression of ectopic calcifications

    Optimum Quantum Error Recovery using Semidefinite Programming

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    Quantum error correction (QEC) is an essential element of physical quantum information processing systems. Most QEC efforts focus on extending classical error correction schemes to the quantum regime. The input to a noisy system is embedded in a coded subspace, and error recovery is performed via an operation designed to perfectly correct for a set of errors, presumably a large subset of the physical noise process. In this paper, we examine the choice of recovery operation. Rather than seeking perfect correction on a subset of errors, we seek a recovery operation to maximize the entanglement fidelity for a given input state and noise model. In this way, the recovery operation is optimum for the given encoding and noise process. This optimization is shown to be calculable via a semidefinite program (SDP), a well-established form of convex optimization with efficient algorithms for its solution. The error recovery operation may also be interpreted as a combining operation following a quantum spreading channel, thus providing a quantum analogy to the classical diversity combining operation.Comment: 7 pages, 3 figure

    USE OF HISTORICAL AERIAL IMAGES FOR 3D MODELLING OF GLACIERS IN THE PROVINCE OF TRENTO

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    Abstract. Historical aerial images represent a source of information of great value for glacier monitoring, as they cover the area of interest at a well-defined epoch and allow for visual interpretation and metric analysis. Typically, the aerial images are used to produce orthophotos and manually digitize the perimeters of the glaciers for analysis of the surface extent of the glaciers, while the extraction of height information is more challenging due to data quality and characteristics. This article discusses the potential of historical aerial images for glacier modelling. More specifically, it analyses the impact of their coverage, radiometric- and geometric accuracy, state of preservation and completeness on the photogrammetric workflow. The data set used consists of scans of 300 (analog) aerial images acquired between August and October 1954 by the U.S. Air Force with a Fairchild KF7660 camera over the entire Province of Trento. For the modelling of the glaciers, different techniques such as manual stereoscopic measurement and dense image matching were tested on sample glaciers and the results were analysed in detail. Due to local radiometric saturation in a large part of the glacial surfaces and other disturbances affecting the historical images (e.g. scratches, scanning errors, dark shadows), dense image matching did not produce any valuable results, and stereo plotting could be used only on images (or image parts) with acceptable quality. The derived Digital Terrain Models (DTMs) were compared with a reference DTM obtained with dense image matching from digital aerial images acquired in September 2015 with an UltraCam Eagle sensor, and, for some glaciers, to a DTM obtained with dense image matching from scanned aerial images acquired in September 1983 with a RC30 analog camera. The differences between 1954 and 2015 DTMs showed values up to 70–80 m in height and a behaviour that is confirmed by the models employed by the glaciology experts in Trento
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