6,025 research outputs found

    Extended Photometry for the DEEP2 Galaxy Redshift Survey: A Testbed for Photometric Redshift Experiments

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    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys; the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform dataset. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains ~27,000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.Comment: 12 pages, 6 figures and 5 tables. Accepted to The Astrophysical Journal Supplement. Catalogs are publicly available at http://deep.ps.uci.edu/DR4/photo.extended.htm

    Optically stimulated nanodosimeters with high storage capacity

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    In this work we report on the thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of beta-Na(Gd,Lu)F-4:Tb3+ nanophosphors prepared via a standard high-temperature coprecipitation route. Irradiating this phosphor with X-rays not only produces radioluminescence but also leads to a bright green afterglow that is detectable up to hours after excitation has stopped. The storage capacity of the phosphor was found to be (2.83 +/- 0.05) x 10(16) photons/gram, which is extraordinarily high for nano-sized particles and comparable to the benchmark bulk phosphor SrAl2O4:Eu2+,Dy3+. By combining TL with OSL, we show that the relatively shallow traps, which dominate the TL glow curves and are responsible for the bright afterglow, can also be emptied optically using 808 or 980 nm infrared light while the deeper traps can only be emptied thermally. This OSL at therapeutically relevant radiation doses is of high interest to the medical dosimetry community, and is demonstrated here in uniform, solution-processable nanocrystals

    An Environmental and Cost Analysis of Stamping Sheet Metal Parts

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    Little work has been done on quantifying the environmental impacts and costs of sheet metal stamping. In this work, we present models that can be used to predict the energy requirements, global warming potential, human health impacts, and costs of making drawn parts using zinc (kirksite) die-sets and hydraulic or mechanical presses. The methodology presented can also be used to produce models of stamping using other die materials, such as iron, for which casting data already exists. An unprecedented study on the environmental impacts and costs of zinc die-set production was conducted at a leading Michigan die-maker. This analysis was used in conjunction with electrical energy measurements on forming presses to complete cradle-to-gate impact and cost analyses on producing small batch size hood and tailgate parts. These case studies were used to inform a generalized model that allows engineers to predict the impacts and costs of forming based on as little information as the final part material, surface area, thickness, and batch size (number of units produced). The case studies show that the press electricity is an insignificant contributor to the overall impacts and costs. The generalized models highlight that while costs for small batch production are dominated by the die-set, the environmental impacts are often dominated by the sheet metal. These findings explain the motivation behind the research into die-less forming processes such as incremental sheet forming, and emphasize the need to minimize the sheet metal scrap generation in order to reduce environmental impacts.United States. Department of Energy (Grant DOE/EE-0998

    Effect of social status on behavioral and neural response to stress

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    Individuals respond differently to traumatic stress. Social status, which plays a key role in how animals experience and interact with their social environment, may influence how individuals respond to stressors. In this study, we used a conditioned defeat model to investigate whether social status alters susceptibility to the behavioral and neural consequences of traumatic stress. Conditioned defeat is a model in Syrian hamsters in which an acute social defeat encounter results in a long term increase in submissive behavior and a loss of normal territorial aggression. To establish social status, we weight matched and paired Syrian hamsters in daily aggressive encounters for two weeks to create dominant/subordinate relationships. We also included controls which were exposed daily to a clean empty cage for the same 14 day period. Twenty-four hours after the final pairing or empty cage exposure, subjects were divided into defeat and no defeat groups. Individuals in the defeat group received three 5 minute social defeats at 5 minute intervals in the cage of a larger aggressive hamster. Individuals in the no defeat group were exposed to the empty cage of a larger aggressive hamster at the same time intervals. In experiment 1, subjects of both groups were tested for conditioned defeat with a non-aggressive intruder 24 hours after social defeat training. In experiment 2, brains were collected 65 minutes following social defeat training and immunohistochemistry was performed for c-Fos protein, a marker of neural activation. We quantified the number of c-Fos immunopositive cells in brain regions known to be involved in stress and aggression, including the ventral medial prefrontal cortex, medial amygdala, and lateral and ventromedial hypothalamus. We found that subordinate animals showed significantly more conditioned defeat behavior than did dominants or controls, and subordinates showed significantly less c-Fos immunoreactivity than did dominants in all these brain regions. These results suggest that decreased neural activity in these brain regions corresponds to an increased susceptibility to conditioned defeat. In sum, social status plays an important role in how animals respond to social stressors and this corresponds to activity in specific brain areas

    Kiloparsec-scale Spatial Offsets in Double-peaked Narrow-line Active Galactic Nuclei. I. Markers for Selection of Compelling Dual Active Galactic Nucleus Candidates

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    Merger-remnant galaxies with kpc-scale separation dual active galactic nuclei (AGNs) should be widespread as a consequence of galaxy mergers and triggered gas accretion onto supermassive black holes, yet very few dual AGNs have been observed. Galaxies with double-peaked narrow AGN emission lines in the Sloan Digital Sky Survey are plausible dual AGN candidates, but their double-peaked profiles could also be the result of gas kinematics or AGN-driven outflows and jets on small or large scales. To help distinguish between these scenarios, we have obtained spatial profiles of the AGN emission via follow-up long-slit spectroscopy of 81 double-peaked narrow-line AGNs in SDSS at 0.03 < z < 0.36 using Lick, Palomar, and MMT Observatories. We find that all 81 systems exhibit double AGN emission components with ~kpc projected spatial separations on the sky, which suggests that they are produced by kpc-scale dual AGNs or kpc-scale outflows, jets, or rotating gaseous disks. In addition, we find that the subsample (58%) of the objects with spatially compact emission components may be preferentially produced by dual AGNs, while the subsample (42%) with spatially extended emission components may be preferentially produced by AGN outflows. We also find that for 32% of the sample the two AGN emission components are preferentially aligned with the host galaxy major axis, as expected for dual AGNs orbiting in the host galaxy potential. Our results both narrow the list of possible physical mechanisms producing the double AGN components, and suggest several observational criteria for selecting the most promising dual AGN candidates from the full sample of double-peaked narrow-line AGNs. Using these criteria, we determine the 17 most compelling dual AGN candidates in our sample.Comment: 12 pages, 8 figures, published in ApJ. Modified from original version to reflect referee's comment

    Medical Migration to the U.S.: Trends and Impact

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    The United States is in the midst of a prolonged nursing shortage, one that could reach a deficit of 800,000 registered nurses (RNs) by 2020. Increasingly, foreign-trained nurses are migrating to the U.S., particularly from low-income countries, seeking higher wages and a higher standard of living. Increased reliance on immigration may adversely affect health care in lower-income countries without solving the U.S. shortage. This Issue Brief analyzes trends in medical migration, and explores its short and long-term effects on the health care workforce in the U.S. and in developing countries

    The potential for material circularity and independence in the U.S. steel sector

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    Achieving a U.S. circular economy would reduce environmental impacts and increase material independence. This article calculates maximum recycled contents (RCs) and recycling rates (RRs) in an independent U.S. steel sector, and estimates the potential to displace current imports with recycled scrap that is currently destined for landfill, hibernating stocks, or export (LHSE). A U.S. dynamic material flow analysis (1880–2100) is conducted to estimate annual steel consumption and scrap generation. The results are coupled with a linear optimization model that minimizes primary steel demand while satisfying the volumetric and compositional demands of new consumption. The compositional analysis examines only copper content because it is of greatest concern to recyclers.The best estimate is that the maximum independent RR is already constrained by copper contamination. Without interventions, this maximum RR will gradually decline throughout the century. The annual consumption to scrap availability ratio (C2SR) will decrease from around 1.4 today. Concurrently, the maximum RC rises but then plateaus below 75% as the RR falls. This highlights a conflict in the conditions for a circular economy: a C2SR approaching unity is a necessary condition for a high RC but leads to fewer opportunities for scrap contaminant dilution, which decreases the RR. Improved product design for recycling and deployment of scrap refining technologies will be needed to reach higher RCs. In 2017, the mass of U.S. scrap destined for LHSE exceeded direct steel imports. Domestic recycling of scrap exports alone could have displaced 36% of direct steel imports, reducing the U.S. deficit by $5.5 billion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156151/3/jiec12971-sup-0001-SuppMatS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156151/2/jiec12971_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156151/1/jiec12971.pd
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