10,086 research outputs found
Bearing servicing tool
A tool for removing and/or replacing bearings in situ is presented. The tool is comprised of a brace having a first end adapted to engage a first end of the bearing housing, and a second end adapted to engage a second end of the bearing housing. If the two ends of the bearing housing are different in configuration, then the respective ends of the brace are configured accordingly. An elongate guide member integral with the brace has two parts, each projecting endwise from a respective end of the brace. A removable pressure plate can be mounted on either part of the guide member for longitudinal movement therealong and has first and second ends of different configurations adapted to engage the first and second ends of the bearing. A threaded-type drive is cooperative between the guide and the pressure plate to move the pressure plate longitudinally along the guide and apply a force to the bearing, either to remove the bearing from its housing, or to emplace a new bearing in the housing
Environment for the People
Environment for the People, a joint publication of PERI and the Centre for Science and the Environment (CSE) in India, documents innovative strategies used by environmental activists around the world to build natural assets. In diverse landscapes, from Bangladesh's riverine delta to Somalia's arid uplands, ommunities are investing in ecological restoration. In 'extractive reserves' in the Amazon rainforest, the defense of sustainable livelihoods goes hand-in-hand with defense of bio-diversity. In the Peruvian Andes, indigenous communities are fighting to protect their lands and water from the ravages of the mining industry. And in cities around the world, from Los Angeles to New Delhi, communities are mobilizing to defend the right to clean air. These and other inspiring cases profiled in Environment for the People illustrate that humankind does not face an inexorable 'tradeoff' between protecting the natural environment and improving economic well-being. On the contrary, struggles for environmental protection and sustainable livelihoods are bound together
Ephemeral Nebular Components in the Mildly Aqueously Altered CM Carbonaceous Chondrite LEW 85311
No abstract available
Measuring Corporate Environmental Justice Performance
Measures of corporate environmental justice performance can be a valuable tool in efforts to promote corporate social responsibility and to document systematic patterns of environmental injustice. This paper develops such a measure based on the extent to which toxic air emissions from industrial facilities disproportionately impact racial and ethnic minorities and low-income people. Applying the measure to 100 major corporate air polluters in the United States, we find wide variation in the extent of disproportional exposures. In a number of cases, minorities bear more than half of the total human health impacts from the firm's industrial air pollution.Corporate social responsibility; corporate environmental performance; environmental justice; air pollution
Evidence for Widespread Post-Hydration Heating of the CM Carbonaceous Chondrites
No abstract available
Syntheses of (+)-30-epi-, (-)-6-epi-, (±)-6,30-epi-13,14-didehydroxyisogarcinol and (±)-6,30-epi-garcimultiflorone A utilizing highly diastereoselective, Lewis acid-controlled cyclizations
The first syntheses of 13,14-didehydroxyisogarcinol (6) and garcimultiflorone A (5) stereoisomers are reported in six steps from a commercially available phloroglucinol. Lewis acid-controlled, diastereoselective cationic oxycyclizations enabled asymmetric syntheses of (-)-6-epi-6 and (+)-30-epi-6. A similar strategy enabled production of the meso-dervied isomers (±)-6,30-epi-6 and (±)-6,30-epi-5. Finally, a convenient strategy for gram scale synthesis was developed utilizing diastereomer separation at a later stage in the synthesis that minimized the number of necessary synthetic operations to access all possible stereoisomers.R01 GM073855 - NIGMS NIH HHS; R24 GM111625 - NIGMS NIH HHS; R35 GM118173 - NIGMS NIH HH
Perturbative Analysis of Spectral Singularities and Their Optical Realizations
We develop a perturbative method of computing spectral singularities of a
Schreodinger operator defined by a general complex potential that vanishes
outside a closed interval. These can be realized as zero-width resonances in
optical gain media and correspond to a lasing effect that occurs at the
threshold gain. Their time-reversed copies yield coherent perfect absorption of
light that is also known as an antilaser. We use our general results to
establish the exactness of the n-th order perturbation theory for an arbitrary
complex potential consisting of n delta-functions, obtain an exact expression
for the transfer matrix of these potentials, and examine spectral singularities
of complex barrier potentials of arbitrary shape. In the context of optical
spectral singularities, these correspond to inhomogeneous gain media.Comment: 13 pages, 2 figures, one table, a reference added, typos correcte
Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep and thermal fatigue
This report presents the results of a fourth year effort of a research program, conducted for NASA-LeRC by the University of Texas at San Antonio (UTSA). The research included on-going development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subject to a number of effects or primitive variables. These primitive variables may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above-described constitutive equation using actual experimental materials data together with regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 has been analyzed using the developed methodology
Money and happiness : rank of income, not income, affects life satisfaction
Does money buy happiness, or does happiness come indirectly from the higher rank in society that money brings? Here we test a rank hypothesis, according to which people gain utility from the ranked position of their income within a comparison group. The rank hypothesis contrasts with traditional reference income hypotheses, which suggest utility from income depends on comparison to a social group reference norm. We find that the ranked position of an individual’s income predicts general life satisfaction, while absolute income and reference income have no effect. Furthermore, individuals weight upward comparisons more than downward comparisons. According to the rank hypothesis, income and utility are not directly linked: Increasing an individual’s income will only increase their utility if ranked position also increases and will necessarily reduce the utility of others who will lose rank
The application of S isotopes and S/Se ratios in determining ore-forming processes of magmatic Ni–Cu–PGE sulfide deposits: a cautionary case study from the northern Bushveld Complex
The application of S/Se ratios and S isotopes in the study of magmatic Ni–Cu–PGE sulfide deposits has long been used to trace the source of S and to constrain the role of crustal contamination in triggering sulfide saturation. However, both S/Se ratios and S isotopes are subject to syn- and post-magmatic processes that may alter their initial signatures. We present in situ mineral δ34S signatures and S/Se ratios combined with bulk S/Se ratios to investigate and assess their utility in constraining ore-forming processes and the source of S within magmatic sulfide deposits.
Magmatic Ni–Cu–PGE sulfide mineralization in the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex was used as a case study based on well-defined constraints of sulfide paragenesis and local S isotope signatures. A crustal δ34S component is evident in the most primary sulfide assemblage regardless of footwall lithology, and is inferred that the parental magma(s) of the GNPA member was crustally contaminated and sulfide saturated at the time of emplacement. However, S/Se ratios of both the primary and in particular secondary sulfide assemblages record values within or below the mantle range, rather than high crustal S/Se ratios. In addition, there is a wide range of S/Se ratio for each sulfide mineral within individual assemblages that is not necessarily consistent with the bulk ratio. The initial crustal S/Se ratio is interpreted to have been significantly modified by syn-magmatic lowering of S/Se ratio by sulfide dissolution, and post-magmatic lowering of the S/Se ratio from hydrothermal S-loss, which also increases the PGE tenor of the sulfides. Trace element signatures and variations in Th/Yb and Nb/Th ratios support both an early pre-emplacement contamination event as seen by the S isotopes and S/Se ratios, but also a second contamination event resulting from the interaction of the GNPA magma with the local footwall country rocks at the time of emplacement; though this did not add any additional S. We are able to present an integrated emplacement and contamination model for the northern limb of the Bushveld Complex.
Although the multitude of processes that affect variations in the δ34S signature and in particular S/Se ratio may be problematic in interpreting ore genesis, they can reveal a wealth of additional detail on a number of processes involved in the genetic history of a Ni–Cu–PGE deposit in addition to crustal contamination. However, a prerequisite for being able to do this is to utilize other independent petrological and mineralogical techniques that provide constraints on both the timing and effect of various ore-forming and modifying processes. Utilizing both bulk and in situ methods in concert to determine the S/Se ratio allows for the assessment of multiple sulfide populations, the partitioning behaviour of Se during sulfide liquid fractionation and also the effects of low temperature fluid alteration. In comparison, S isotopes are relatively more robust and represent a more reliable indicator of the role of crustal S contamination. The addition of trace element data to the above makes for an incredibly powerful approach in assessing the role of crustal contamination in magmatic sulfide systems
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