3,830 research outputs found
Distributional Considerations in the Overregulation of Health Professionals, Health Facilities, and Health Plans
Conover addresses the equity issue in health care spending. Conover concludes that the marginal impact of health regulation is to make the US health system more, rather than less, regressive
Preliminary Investigation on the Physiology and Ecology of Luminescence in the Copepod, Metridia lucens
1. Skin glands believed to be the source of luminescence were found on the anterior portion of the head, on the last thoracic segment, and on the posterior margins of each segment of the abdomen.
2. The maximum intensity of the luminescent flash was 1.2 x 10-3 µw./cm.2 (at 18 cm.). The flash rose rapidly to peak intensity and then decayed slowly. The total duration of the flashes with peaks greater than 10-4 µw./cm.2 ranged from 3 to 50 seconds.
3. The peak of the luminescence spectrum occcurred at 482 mµ and the curve fell off to one-half the maximum value at 440 mµ and 525 mµ.
4. The ability of Metridia to luminesce on stimulation was found to be largely unaffected by prolonged laboratory culture. Starvation had little effect on the luminescence for the first three weeks and there was never any inhibition by previous light- or dark-adaptation.
5. With an increase in the strength of the electric stimulus from 0.3 amp. to 0.7 amp., the intensity of the luminescent flash was found to increase. With pulses stronger than 0.7 amp. no change in intensity was recorded but the number of successive responses to repeated stimuli was reduced. Duration of the pulse had little effect on the intensity or the number of successive responses.
6. Metridia showed a lag time of 8-10 msc. to the beginning of the luminescent response. The lag time to the peak of the luminescent response varied from 20 to 60 msc.
7. There was no spontaneous luminescence produced by groups of Metridia under conditions of constant darkness. However, the presence of certain planktonic predators, most notably Meganyctiphanes norvegica, caused a brilliant display of luminescence. The number of flashes attributable to Metridia was always greater than the number of Metridia eaten by the predator. There was little evidence that the luminescent euphausiid, Meganyctiphanes, flashed spontaneously either in the presence or absence of its prey.
8. Observations on the behavior of Metridia during and just after luminescence suggest that the flashing may be involved in an escape mechanism, but the precise effect of the light on the predator has not been determined
Earth science data study
The research proposed in this contract concerning investigations of existing and planned Earth Science and Applications Division (ESAD) data management systems and research into utilities for the access and display of scientific data products was completed. A summary of this work is provided
Some Locally Most Powerful Rank Tests For Correlation
Four examples are given to illustrate the ease and practicality of the procedure for finding locally most powerful rank tests for correlation. The first two examples deal with bivariate exponential models. The third example uses the bivariate normal distribution, and the fourth example analyzes the Morgenstem’s general correlation model
Abundance and distribution of Atlantic sturgeon (Acipenser oxyrinchus) within the Northwest Atlantic Ocean, determined from five fishery-independent surveys
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Evaluation of semiochemical based push-pull strategy for population suppression of ambrosia beetle vectors of laurel wilt disease in avocado.
Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) bore into tree xylem to complete their life cycle, feeding on symbiotic fungi. Ambrosia beetles are a threat to avocado where they have been found to vector a symbiotic fungus, Raffaelea lauricola, the causal agent of the laurel wilt disease. We assessed the repellency of methyl salicylate and verbenone to two putative laurel wilt vectors in avocado, Xyleborus volvulus (Fabricius) and Xyleborus bispinatus (Eichhoff), under laboratory conditions. Then, we tested the same two chemicals released from SPLAT flowable matrix with and without low-dose ethanol dispensers for manipulation of ambrosia beetle populations occurring in commercial avocado. The potential active space of repellents was assessed by quantifying beetle catch on traps placed 'close' (~5-10 cm) and 'far' (~1-1.5 m) away from repellent dispensers. Ambrosia beetles collected on traps associated with all in-field treatments were identified to species to assess beetle diversity and community variation. Xyleborus volvulus was not repelled by methyl salicylate (MeSA) or verbenone in laboratory assays, while X. bispinatus was repelled by MeSA but not verbenone. Ambrosia beetle trap catches were reduced in the field more when plots were treated with verbenone dispensers (SPLAT) co-deployed with low-dose ethanol dispensers than when treated with verbenone alone. Beetle diversity was highest on traps deployed with low-dose ethanol lures. The repellent treatments and ethanol lures significantly altered the species composition of beetles captured in experiment plots. Our results indicate that verbenone co-deployed with ethanol lures holds potential for manipulating ambrosia beetle vectors via push-pull management in avocado. This tactic could discourage immigration and/or population establishment of ambrosia beetles in commercial avocado and function as an additional tool for management programs of laurel wilt
WILDLIFE DAMAGE TO CROPS: PERCEPTIONS OF AGRICULTURAL AND WILDLIFE PROFESSIONALS IN 1957 AND 1987
We surveyed state wildlife agencies, state agricultural departments, Wildlife Extension Specialists, U.S.D.A. Animal Damage Control agents, and state Farm Bureau officials to develop a national perspective of wildlife damage to agricultural crops in the U.S. A broad concensus existed that wildlife damage was a major problem, although groups often differed in their perceptions of the seriousness of specific problems. The complexity of the wildlife damage problem was apparent in that 27 different wildlife species were cited as causing the greatest problem to a state\u27s farmers. Nevertheless, 38-80% of the respondents from every group surveyed stated that deer were their worst problem. Most respondents believed that wildlife damage had increased in the last 30 years. Increasing levels of wildlife damage also were apparent when we compared our findings to those of a similar survey conducted in 1957 (McDowell and Pillsbury 1958). For instance in 1957, 16 states reported that deer were either no problem or only caused localized problems, while in our survey, 15 of these 16 states stated that deer were now causing more damage to crops than any other wildlife species
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