The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong-CP problem in the Standard Model. The coupling of the axion to photons is the most common ...experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly motivated region 0.4–120 neV, corresponding to a GUT-scale axion, is particularly difficult to reach. This paper presents the design requirements for a definitive search for GUT-scale axions and reviews the technological advances needed to enable this program.
Addressing failures in exascale computing Snir, Marc; Wisniewski, Robert W; Abraham, Jacob A ...
International journal of high performance computing applications/The international journal of high performance computing applications,
05/2014, Letnik:
28, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present here a report produced by a workshop on ‘Addressing failures in exascale computing’ held in Park City, Utah, 4–11 August 2012. The charter of this workshop was to establish a common ...taxonomy about resilience across all the levels in a computing system, discuss existing knowledge on resilience across the various hardware and software layers of an exascale system, and build on those results, examining potential solutions from both a hardware and software perspective and focusing on a combined approach.
The workshop brought together participants with expertise in applications, system software, and hardware; they came from industry, government, and academia, and their interests ranged from theory to implementation. The combination allowed broad and comprehensive discussions and led to this document, which summarizes and builds on those discussions.
Polycrystalline ZnS produced by chemical vapor deposition (CVD) is analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD) to ...gain insight into the growth mechanism. Epitaxial growth of ZnS (111) layers is indicated in cubic CVD-ZnS. Mechanisms counteracting the growth of large, homogeneously oriented grains are proposed. This includes the summation of faults at low-angle grain boundaries during the deposition of new layers as well as the formation of new growth directions perpendicular to the sides of large grains. Wurtzite could be identified as a product of instable deposition conditions at the beginning and end of the deposition process.
This paper estimates the impact of nutrition and health problems on test scores of grade four students in Sri Lanka using a rich dataset on child height, weight, hearing and vision problems, ...helminthes infections, malaria, and micronutrient deficiencies. The results show that stunting and hearing problems in children have
direct impact on tests scores and an
indirect effect as parents may adjust to small changes in nutrition and health by changing the education inputs provided to their child. Further, omitting health problems from estimation generally causes an upward bias in estimates of stunting, a common measure of overall child health.
The Remote Sensing Group at the University of Arizona has used ground-based test sites for the vicarious calibration of airborne and satellite-based sensors, of which the Railroad Valley Playa in ...north central Nevada has played a key role. This work presents a cross comparison of five satellite-based sensors that all imaged this playa on July 16, 2001. These sensors include the Advanced Land Imager and Hyperion on the Earth Observer-1 platform, the Landsat-7 Enhanced Thematic Mapper Plus (ETM+), Terra's Moderate Resolution Imaging Spectroradiometer, and Space Imaging's Ikonos. The approach atmospherically corrects the ETM+ data to derive surface reflectance for a 1 km /spl times/ 1 km area of the playa and then uses these reflectances to determine a hyperspectral at-sensor radiance for each of the sensors taking into account the changes in solar zenith angle due to any temporal differences in the overpass times as well as differences in the view angles between the sensors. Results show that all of the sensors agree with ETM+ to within 10% in the solar reflective for bands not affected by atmospheric absorption. ETM+, MODIS, and ALI agree in all bands to better than 4.4% with better agreement in the visible and near infrared. Poorer agreement between Hyperion and other sensors appears to be due partially to poorer signal to noise ratio in the narrowband Hyperion datasets.
Histopathological studies suggest that cerebral small vessel tortuosity is crucial in age-related blood flow reduction and cellular degeneration. However, in vivo evidence is lacking. Here, we used ...Ferumoxytol-enhanced 7T MRI to directly visualize cerebral small vessels (>300 µm), enabling the identification of vascular tortuosity and exploration of its links to age, tissue atrophy, and vascular risk factors. High-resolution 2D/3D gradient echo MRI at 7T enhanced with Ferumoxytol, an ultrasmall superparamagnetic iron oxide (USPIO), was obtained and analyzed for cerebral small medullary artery tortuosity from 37 healthy participants (21-70 years; mean/SD: 38±14 years; 19 females). Tortuous artery count and tortuosity indices were compared between young and old groups. Age effects on vascular tortuosity were examined through partial correlations and multiple linear regression, adjusting for sex, body mass index (BMI), blood pressure (BP), and other vascular risk factors. Associations between tortuous medullary arteries and tissue atrophy, perivascular spaces (PVS), and white matter (WM) hyperintensities were explored. Age and BMI, rather than BP, showed positive correlations with both tortuous artery count and tortuosity indices. A significant correlation existed between the number of tortuous arteries and WM atrophy. WM lesions were found in proximity to or at the distal ends of tortuous medullary arteries, especially within the deep WM. Moreover, the elderly population displayed a higher prevalence of PVS, including those containing enclosed tortuous arteries. Leveraging the blooming effect of Ferumoxytol, 7T MRI excels in directly detecting cerebral small arterial tortuosity in vivo, unveiling its associations with age, BMI, tissue atrophy, WMH and PVS.
The IBM Blue Gene/Q Compute Chip Haring, Ruud A.; Ohmacht, Martin; Fox, Thomas W. ...
IEEE MICRO,
2012-March-April, 2012-03-00, 20120301, Letnik:
32, Številka:
2
Journal Article
Recenzirano
Blue Gene/Q aims to build a massively parallel high-performance computing system out of power-efficient processor chips, resulting in power-efficient, cost-efficient, and floor-space- efficient ...systems. Focusing on reliability during design helps with scaling to large systems and lowers the total cost of ownership. This article examines the architecture and design of the Compute chip, which combines processors, memory, and communication functions on a single chip.
Hepcidin is a primary regulator of iron metabolism in the human body. By promoting ferroportin degradation, hepcidin reduces intestinal iron absorption and its release from intracellular stores. In ...the course of pregnancy, gradually declining hepcidin concentrations encourage placental iron transfer, thereby providing the appropriate amount of iron for fetal development. Hence, we aimed to investigate changes in maternal and cord blood hepcidin and iron metabolism parameters in normal-weight (n=17) and obese (n=17) gestating women, as well as gravid women with a history of hypothyroidism following the restoration of euthyroidism (n=17). All blood samples were taken on the day of delivery, and ELISA kits were used for measurements. A significant increase in maternal hepcidin concentration was observed in obese pregnant women, compared to normal-weight controls (29.53±4.20 ng/mL vs. 25.69±5.70 ng/mL; P<0.05). However, only a slight, insignificant tendency for lower hepcidin was noted in the hypothyroid group, compared to the healthy controls (23.10±6.00 ng/mL vs. 25.69±5.70 ng/mL; P=NS). Moreover, decreased maternal free triiodothyronine, triiodothyronine, free thyroxine, and ferritin levels were revealed in the hypothyroid group, compared to the normal-weight individuals (P<0.05). Furthermore, positive correlations between maternal hepcidin and the majority of maternal thyroid hormones were found, with a most potent relation to FT3 (r=0.40; P<0.01). Interestingly, no alterations of thyroid hormones and iron metabolism parameters were noticed in cord blood in any of the subgroups. In summary, pre-pregnancy obesity is associated with elevated maternal hepcidin, albeit no signs of lowered cord blood iron status were shown. Medical history of hypothyroidism following the restoration of euthyroidism does not substantially influence maternal nor cord blood hepcidin concentration, as well as fetal iron homeostasis, even though free thyroid hormone levels correlate with maternal hepcidin.
The Remote Sensing Group at the University of Arizona has been using ground targets for the in-flight vicarious calibration of airborne and satellite sensors since the early 1980s. Targets such as ...Railroad Valley Playa in north central Nevada and White Sands Missile Range in New Mexico have proven to be useful for this work. This paper presents the results from multiple vicarious calibration experiments at a variety of sites for two of the Earth Observing 1 (EO-1) optical sensors. The Advanced Land Imager (ALI) and Hyperion sensors operate in the visible and shortwave infrared portions of the spectrum. The ground sample distance of about 30 m works well for vicarious calibration and allows an easy comparison to legacy sensors such as the Enhanced Thematic Mapper Plus (ETM+) which has the same 30-m ground sample distance. The approach used in this work is to measure the surface reflectance and atmospheric properties during the sensor image acquisition. These data are used as input to a radiative transfer code which computes the top of atmosphere spectral radiance. This predicted radiance is compared to the radiance from the image of the site. Results show that the preflight calibrations of ALI and Hyperion are probably not consistent with in-flight performance of the instruments. New calibration coefficients adopted in December 2001 improve the comparison to the vicarious predictions.
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