8,774 research outputs found

    "The Measurement of Chronic and Transitory Poverty: with Application to the United States"

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    This paper proposes a method of measuring chronic and transitory poverty based on any additively-decomposable index of aggregate poverty. Chronic poverty and transitory poverty in the United States are measured using data from the Panel Study of Income Dynamics (1987 interviewing year). In an attempt to identify the most impoverished subpopulations, poverty indices are decomposed according to race, type of household and educational qualifications of the head of the household.

    Utilization of the graded universal testing system to increase the efficiency for assessing aerobic and anaerobic capacity

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    The in-flight exercise test performed by cosmonauts as part of the Russian Exercise Countermeasure Program is limited to 5 minutes due to communication restrictions. During a recent graded exercise test on a U.S. Shuttle flight, the test was terminated early due to an upcoming loss of signal (LOS) with the ground. This exercise test was a traditional test where the subject's exercise capacity dictates the length of the test. For example, one crew member may take 15 minutes to complete the test, while another may take 18 minutes. The traditional exercise test limits the flight schedulers to large blocks of space flight time in order to provide medical and research personnel information on the fitness capacity (maximal oxygen uptake: VO2max) of crew members during flight. A graded exercise test that would take a finite amount of time and a set preparation and recovery time would ease this problem by allowing flight schedulers to plan exercise tests in advance of LOS. The Graded Universal Testing System (GUTS) was designed to meet this goal. Fitness testing of astronauts before and after flight provides pertinent data on many variables. The Detailed Supplemental Objective (DSO608) protocol (6) is one of the graded exercise tests (GXT) currently used in astronaut testing before and after flight. Test times for this protocol have lasted from 11 to 18 minutes. Anaerobic capacity is an important variable that is currently not being evaluated before and after flight. Recent reports (1,2,5) from the literature have suggested that the oxygen deficit at supramaximal exercise is a measure of anaerobic capacity. We postulated that the oxygen deficit at maximal exercise would be an indication of anaerobic capacity. If this postulate can be accepted, then the efficiency of acquiring data from a graded exercise test would increase at least twofold. To examine this hypothesis anaerobic capacity was measured using a modified treadmill test (3,4) designed to exhaust the anaerobic systems in approximately 45 to 75 seconds. Lactate concentration in the blood was analyzed after all tests, since lactate is the end-product of anaerobic energy production. Therefore, the peak lactate response is an additional indication of anaerobic capacity. A preliminary comparison of the GUTS and the DSO608 suggests that the GUTS protocol would increase the efficiency of VO2max testing of astronauts before and after flight. Results for anaerobic capacity have not been tabulated

    Cooled slow-scan performance of a 512 by 320 element charge-coupled imager

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    A 512 x 320 element charge coupled imager has been fabricated and tested under cooled slow scan conditions to evaluate the device's performance under a variety of long integration and slow scan readout conditions. Operation in a low blooming mode of operation enables the sensor to be exposed with portions of the image heavily overexposed, without those areas spreading into adjacent picture areas. Device design, layout, and operating mode are described, and presents experimental results, including displayed images taken under cooled slow scan operation, are reported

    Comparison of epifluorescent viable bacterial count methods

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    Two methods, the 2-(4-Iodophenyl) 3-(4-nitrophenyl) 5-phenyltetrazolium chloride (INT) method and the direct viable count (DVC), were tested and compared for their efficiency for the determination of the viability of bacterial populations. Use of the INT method results in the formation of a dark spot within each respiring cell. The DVC method results in elongation or swelling of growing cells that are rendered incapable of cell division. Although both methods are subjective and can result in false positive results, the DVC method is best suited to analysis of waters in which the number of different types of organisms present in the same sample is assumed to be small, such as processed waters. The advantages and disadvantages of each method are discussed

    Seasonality of birth in nineteenth and twentieth century Austria: steps toward a unified theory of human reproductive seasonality

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    We present an analysis of birth seasonality in nine geographical regions within Austria for two time periods, 1881-1912 and 1947-1959. In the early period, geography, climate, and agricultural patterns were related to birth seasonality. By the later time period, these factors were no longer related to birth seasonality. We propose a “resilience hypothesis,” which suggests two levels of causal influences on birth seasonality. First, underlying the three significant features of birth seasonality patterns around the world are only a small number of major causes. But, second, there are a multiplicity of minor causes that result in small perturbations in the patterns.(AUTHORS)

    Conflict between background matching and social signalling in a colour-changing freshwater fish

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    The ability to change coloration allows animals to modify their patterning to suit a specific function. Many freshwater fishes, for example, can appear cryptic by altering the dispersion of melanin pigment in the skin to match the visual background. However, melanin-based pigments are also used to signal dominance among competing males; thus colour change for background matching may conflict with colour change for social status signalling. We used a colour-changing freshwater fish to investigate whether colour change for background matching influenced aggressive interactions between rival males. Subordinate males that had recently darkened their skin for background matching received heightened aggression from dominant males, relative to males whose coloration had not changed. We then determined whether the social status of a rival male, the focal male's previous social status, and his previous skin coloration, affected a male's ability to change colour for background matching. Social status influenced skin darkening in the first social encounter, with dominant males darkening more than subordinate males, but there was no effect of social status on colour change in the second social encounter. We also found that the extent of skin colour change (by both dominant and subordinate males) was dependent on previous skin coloration, with dark males displaying a smaller change in coloration than pale males. Our findings suggest that skin darkening for background matching imposes a significant social cost on subordinate males in terms of increased aggression. We also suggest that the use of melanin-based signals during social encounters can impede subsequent changes in skin coloration for other functions, such as skin darkening for background matching

    Colour change and assortment in the western rainbowfish

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    Grouping behaviour is widespread across the animal kingdom, and is known to reduce an individual's risk of predation, for example through predator confusion. Theory predicts that individuals that are different in appearance to the rest of the group are at a greater risk of predation because they are more conspicuous to predators (the ‘oddity’ effect). Thus, animals should choose group mates that are the most similar in appearance to themselves. Another common antipredator tactic is crypsis (camouflage). Fishes are capable of changing colour to match their visual background, but few studies have examined how this might influence shoaling decisions, particularly in the context of the oddity effect. We induced colour pattern changes in a colourful species of freshwater fish, the western rainbowfish, Melanotaenia australis, by maintaining fish in dark and pale aquaria for 2 weeks. Analysis of the proportion of black body pigmentation confirmed that rainbowfish in dark environments developed darker colour patterns than those held in pale environments. We then conducted behavioural observations to determine whether fish subsequently based their shoaling decisions on body coloration. We found that rainbowfish preferred to shoal with similar individuals; fish that had been held in dark aquaria preferred to shoal with other dark fish and fish from pale aquaria preferred other pale fish. Our findings are consistent with the predictions of the oddity effect and demonstrate how morphological colour pattern changes and behavioural decisions interact to mediate antipredator tactics in fish

    The Effect of Geographic Mobility on Male Labour-Force Particpants in the United States

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    We use both fixed-effects and random-effects regression models to measure the effect of geographic mobility on earnings of labor-force participants in the United States. The results support the human-capital hypothesis: six years after moving, real earnings of male labor-force participants are about 20 percent higher than they would have been had the move not occurred. Men younger than 40, and men with family-unit incomes no more than five times the poverty line, experience even larger benefits from moving. The geographic mobility that is characteristic of the United States’ flexible labor market, in general, is beneficial to the movers

    Enhancing the development of Black professionals in corporate America

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    The purpose of the study is to focus on the lack of upward mobility and job parity between Black professionals and White professionals. This study points out that the various skills and performances exemplified by many competent Black professionals are not being utilized or rewarded adequately. The emphasis as its basis revolved around competency with strategy to alleviate ethnicity, gender, or creed. To investigate the attitudes of upper level managers, mid-level managers, and the sales representatives regarding Black awareness and career development, I will administer a questionnaire to eight regional managers and forty-two divisional managers throughout Ortho Pharmaceutical Corporation. In addition, a questionnaire will be administered to the Black sales representatives to determine their perception of their job and their attitude regarding career development. The results will then enable the problem to be defined and a solution designed to overcome the problem
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