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111.
Placental biopsy was performed on 81 patients at greater than 16 weeks' gestation. The major indication for such biopsies was an increased risk of chromosomal abnormality because of either abnormal ultrasound findings or late presentations for advanced maternal age. Six abnormal karyotypes resulting in elective termination were found. The use of rapid karyotyping by this procedure as an alternative to amniocentesis or fetal blood sampling is discussed. 相似文献
112.
Hien V. Dao Lauren A. Maher Lawrence N. Ngeh Stephen W. Bigger John D. Orbell Margaret Healy Rosalind Jessop Peter Dann 《Environmental Chemistry Letters》2006,4(2):111-113
A previously reported acute temperature dependency for the effective removal of tarry residue from feather clusters, utilising magnetic particles, has also been demonstrated to occur for the plumage of whole birds, whereby a maximum removal of up to 96% may be achieved. The experimental design allows an approximate equilibrium constant, for the distribution of contaminant between the residue and the magnetic particles, to be estimated at each temperature. This allows the thermodynamics of the process to be examined via application of the van't Hoff equation, suggesting an explanation for the phenomenon. 相似文献
113.
Ruurd de Jong Nevile Maher Bruno Patrian Erich St?dler Tammo Winkler 《Chemoecology》2000,10(4):205-209
Summary. Two recently identified compounds ("CIFs"), present on the leaf surface of Brassica oleracea (cabbage), are the strongest oviposition stimulants known for the cabbage root fly, Delia radicum. Cabbage leaves contain these compounds in extremely low concentrations, and the amount of CIFs obtained from purifying leaf
extracts was so small that it limited further research. We were able to purify far more of these two compounds from the roots
of Brassica napus var. napobrassica (rutabaga). Apart from being a richer source of CIFs, rutabaga roots are considerably easier to collect and process than
leaves. In addition, we isolated and identified a new CIF compound from the roots that is also very active in stimulating
oviposition in the cabbage root fly.
Received 26 May 2000; accepted 26 July 2000 相似文献
114.
115.
C. R. Maher 《Behavioral ecology and sociobiology》2000,47(5):327-338
Whereas variation in pronghorn (Antilocapra americana) spatial organization is well documented, underlying ecological or physiological explanations are not well understood. This
study quantitatively describes spacing systems of pronghorn males and correlates of their spatial organization. I collected
behavioral data from two populations in South Dakota (Wind Cave) and Montana (Bar Diamond) to determine if males differed
in space use, response to intruders, and behavior patterns indicative of area defense. I measured sex ratio and population
density, and I examined characteristics of food resources, including forb species diversity, richness, coverage, biomass,
and nitrogen content, and how they changed during the growing season. I also collected and analyzed fecal samples to determine
if males differed in testosterone concentrations. Pronghorn males at Wind Cave were more territorial than males at Bar Diamond,
although males at Bar Diamond became more territorial during the second year. The forb community at Wind Cave was more diverse,
contained greater amounts of forbs later in summer, and had a higher nitrogen content later in summer. Population density
was lower at Wind Cave, although density dropped at Bar Diamond during the second year, and sex ratios were skewed toward
males at Bar Diamond. Finally, males at Wind Cave had higher testosterone concentrations than did Bar Diamond males, although
differences were not statistically significant. With lower population density and higher forb abundance and quality, food
resources were more economically defensible at Wind Cave, and males were more territorial there. Analyses using these and
other pronghorn populations revealed that population density and sex ratio correlated weakly with spatial organization, whereas
precipitation correlated most strongly, which suggests plant productivity has a powerful role in determining pronghorn territoriality.
Received: 16 June 1999 / Received in revised form: 21 September 1999 / Accepted: 31 December 1999 相似文献
116.
This article describes the development, use, and learning from a Business Tailored Management System Verification (BTMSV) process. This process is designed to focus on selected Responsible Care activities or programs, and provides broad options to include specific elements to meet more targeted business unit objectives. © 1998 John Wiley & Sons, Inc. 相似文献
117.
For dioecious species, choosing a mate of the same sex can have reproductive costs. For sex-changing animals, however, a lack
of sex recognition may not carry a reproductive cost, as pairs that were initially same-sex can become opposite-sex pairs
as one partner changes sex. The strength of sex discrimination in sex changers, then, should depend on the duration of mating
associations and whether the time of sex change is influenced by social situation (“flexible” sex change). We studied two
species of marine snails that change sex from male to female, one with flexible sex change and long-term or permanent mating
associations (Crepidula fornicata) and one with short-term pairings and relatively fixed time of sex change (Crepidula convexa), to determine whether either species exhibits sex recognition and whether members of C. convexa show stronger sex discrimination. In laboratory experiments, small males, the choosing animals, were placed with either a
male or a female conspecific (no-choice experiments) or given a choice of a male or female (choice experiments). We controlled
for shell length in all experiments, as relative size may influence sex change or choice. Males of both species paired more
often with females than males, but, as predicted, males of C. convexa showed stronger discrimination: When given a choice, no C. convexa male paired with another male. In contrast, some C. fornicata males always chose other males even when given the choice of a female. These results suggest that sex recognition can be
adaptive even for sex changers but demonstrate that the level of sex recognition will depend on other aspects of reproductive
behavior. 相似文献
118.
Extreme events associated with global change will impose increasing stress on coastal organisms. How strong biological interactions
such as the host–parasite arms-race are modulated by environmental change is largely unknown. The immune system of invertebrates,
in particular phagocytosis and phenoloxidase activity response are key defence mechanisms against parasites, yet they may
be sensitive to environmental perturbations. We here simulated an extreme event that mimicked the European heat wave in 2003
to investigate the effect of environmental change on the immunocompetence of the mesograzer Idotea baltica. Unlike earlier studies, our experiment aimed at simulation of the natural situation as closely as possible by using long
acclimation, a slow increase in temperature and a natural community setting including the animals’ providence with natural
food sources (Zostera marina and Fucus vesiculosus). Our results demonstrate that a simulated heat wave results in decreased immunocompetence of the mesograzer Idotea baltica, in particular a drop of phagocytosis by 50%. This suggests that global change has the potential to significantly affect
host–parasite interactions. 相似文献
119.
McCubbin D Leonard KS Young AK Maher BA Bennett S 《Journal of environmental radioactivity》2004,77(2):111-131
An assessment has been made of the association of (239+240)Pu, 241Am and 210Po (in secular equilibrium with 210Pb) with iron minerals using a magnetic extraction technique. Grab samples of beach sand from the Cumbrian (UK) coastline were subjected to successive extractions with an approximately 0.1 T ferrite magnet and an approximately 0.3 T rare-earth magnet procedure to separate magnetic iron oxide minerals. Radionuclide concentrations in the magnetic extracts were enhanced (by approximately 4-6-fold) relative to the residue. Those in the approximately 0.1 T magnet extracts were broadly similar to those in the antiferromagnetic material extracted by the approximately 0.3 T magnet, despite the very large differences in magnetic property values between the two fractions (one to two orders of magnitude). The percentage of magnetic material in terms of mass was small and therefore, the majority of these radionuclides (on average 88%) were associated with the residue. Removal of stable Fe was incomplete. Given that the radionuclides may also bind to paramagnetic (nonmagnetic) Fe minerals, the data were extrapolated by normalising the results to quantitative Fe removal. This yielded average values of 37%, 45% and 46% for (239+240)Pu, 241Am and 210Po(210Pb), respectively, as upper limits for the fraction associated with magnetic + nonmagnetic Fe minerals. There are significant uncertainties inherent in quantifying data from this extraction technique. Nevertheless, it seems reasonable to conclude that radionuclide association with Fe minerals is unlikely to have a significant impact upon the physical dispersion of sediment contaminated by Sellafield discharges in the Irish Sea. However, it may be an important factor in governing Pu redox and redissolution behaviour. 相似文献
120.
Holliman PJ Kalaji M Wheldon-Williams R Evans DL Jones TP 《Journal of environmental monitoring : JEM》2003,5(1):106-110
The effects of relative humidity (40-90% RH) and varying glutaraldehyde vapour concentrations (< 0.1 ppm) on the response of an electrochemical fuel cell sensor have been investigated over time (0-400 s). These studies have identified changes in the response of the fuel cell with time after sampling. In particular, it has been found that the maximum cell output for water vapour occurs ca. 10 s after sampling whilst the response to glutaraldehyde occurs much later (> 100 s). For mixtures containing different ratios of water and glutaraldehyde vapours, the time taken to reach maximum fuel cell response varies between 10 and 100 s, depending on the ratio of the two vapours. For instance, glutaraldehyde vapour containing higher % RH has been found to result in shorter times to reach maximum fuel cell response. A comparison was made between measuring glutaraldehyde vapour concentrations in the presence of water vapour at the maximum fuel cell response and also at a fixed interval (240 s) after sampling. Such a comparison resulted in a reduction in the standard error from 36% to 5% for a glutaraldehyde vapour sample (0.023 ppm) measured at different values of relative humidity (40 to 80%). Examination of the effect of the sample volume (30-60 ml) on the response of the fuel cell shows, as expected, an approximate doubling of the fuel cell response. Optimisation of the fuel cell measurement parameters to measure a 60 ml sample leads to a lowering of the limit of detection from 0.083 ppm (for data taken at the maximum cell response) to 0.017 ppm for data measured 240 s after sampling. In the light of recent reductions in the legal limits for exposure to glutaraldehyde, this has important implications for the measurement of glutaraldehyde vapour in the workplace. 相似文献