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691.
Amélia Viricel Allan E. Strand Patricia E. Rosel Vincent Ridoux Pascale Garcia 《Behavioral ecology and sociobiology》2008,63(2):173-185
Compared to terrestrial mammals, little is known of cetacean social systems as they are generally less accessible to behavioral
investigations due to their aquatic environment. The present study investigates group structure of the pelagic common dolphin,
Delphinus delphis, using genetic markers. Tissue samples from 52 individuals representing a recent live mass-stranding event were compared
to 42 single strandings taken from presumably different groups. The mass-stranding event occurred in 2002 on the French coast
of the English Channel, whereas the single strandings were collected between 1993 and 2003 along the western coast of France
(Bay of Biscay and English Channel). Analysis of mitochondrial DNA control region sequences indicated that genetic variability
within the mass-stranded pod was similar to variability observed in single strandings. The mass-stranded group was composed
of 41 different mitochondrial haplotypes or matrilines while the single strandings revealed 29 different haplotypes. Analysis
of 11 microsatellite loci revealed that average relatedness of the mass-stranded pod was not different from average relatedness
among all single strandings suggesting that individuals within the group had no closer kin relationships than animals taken
from presumably different groups. These results do not support a matriarchal system and suggest that common dolphins constituting
a pod are not necessarily genetically related. 相似文献
692.
María J Lombardero Patricia Vázquez-Mejuto Matthew P Ayres 《Ecological applications》2008,18(5):1171-1181
Plantations of rapidly growing trees are becoming increasingly common because the high productivity can enhance local economies, support improvements in educational systems, and generally improve the quality of life in rural communities. Landowners frequently choose to plant nonindigenous species; one rationalization has been that silvicultural productivity is enhanced when trees are separated from their native herbivores and pathogens. The expectation of enemy reduction in nonindigenous species has theoretical and empirical support from studies of the enemy release hypothesis (ERH) in the context of invasion ecology, but its relevance to forestry has not been evaluated. We evaluated ERH in the productive forests of Galicia, Spain, where there has been a profusion of pine plantations, some with the indigenous Pinus pinaster, but increasingly with the nonindigenous P. radiata. Here, one of the most important pests of pines is the indigenous bark beetle, Tomicus piniperda. In support of ERH, attacks by T. piniperda were more than twice as great in stands of P. pinaster compared to P. radiata. This differential held across a range of tree ages and beetle abundance. However, this extension of ERH to forestry failed in the broader sense because beetle attacks, although fewer on P. radiata, reduced productivity of P. radiata more than that of P. pinaster (probably because more photosynthetic tissue is lost per beetle attack in P. radiata). Productivity of the nonindigenous pine was further reduced by the pathogen, Sphaeropsis sapinea, which infected up to 28% of P. radiata but was absent in P. pinaster. This was consistent with the forestry axiom (antithetical to ERH) that trees planted "off-site" are more susceptible to pathogens. Fungal infections were positively correlated with beetle attacks; apparently T. piniperda facilitates S. sapinea infections by creating wounds and by carrying fungal propagules. A globally important component in the diminution of indigenous flora has been the deliberate large-scale propagation of nonnative trees for silviculture. At least for Pinus forestry in Spain, reduced losses to pests did not rationalize the planting of nonindigenous trees. There would be value in further exploration of relations between invasion ecology and the forestry of nonindigenous trees. 相似文献
693.
Three treatment media, used for the removal of arsenic from drinking water, were sequentially extracted using 10 mM MgCl2(pH 8), 10 mM NaH2PO4(pH 7) followed by 10 mM (NH4)2C2O4(pH 3). The media were extracted using an on-line automated continuous extraction system which allowed the arsenic in each of the extraction fluids to be speciated on-line using IC-ICP-MS. The 10 mM MgCl2 preferentially extracted As(III) from each of the media. The percentage of the arsenic extracted by the MgCl2, relative to a HNO3/H2O2 digestion of the media, ranged from 0.1-2.3% for the three solids. The next sequential extraction fluid, 10 mM NaH2PO4, extracted some of the residual As(III) remaining on each of the media but the predominant species extracted was As(V). The 10 mM NaH2PO4 extracted 15.3 to 42.8% of the total arsenic relative to a total digested concentration for each of the media. The As(III) and As(V) stability studies conducted in these two extraction fluids indicated that conversion between As(III) and As(V) was not significant for the short extraction fluid sample contact time associated with the on-line continuous flow extraction cell. Finally, the 10 mM (NH4)2C2O4 extraction fluid was utilized in an off-line analysis mode because the Fe and As concentrations extracted from the media were not compatible with direct ICP-MS detection. The (NH4)2C2O4 extracted 2.9-29% As(III) for all three media and caused an oxidation of As(III) to As(V) during the extraction period for one of the three media. The sum of the arsenic from each of the three extraction fluids represented 92%, 44% and 53% of the available total arsenic for the three media, respectively. The speciation results for each media were obtained by adding all the speciation results from all three extraction fluids together and the resulting distribution of As(III)/As(V) compared well with the speciation results obtained via XANES. 相似文献
694.
Nancy S. Day Marija Tadin Angela M. Christiano Patricia Lanzano Sergio Piomelli Stephen Brown 《黑龙江环境通报》2002,22(8):686-691
Prenatal diagnosis of sickle cell diseases has been available for several years, and our laboratory has performed over 1000 prenatal diagnoses. However, currently available techniques are labor-intensive and time-consuming, and thus the diagnosis is delayed, making the mother's decision difficult. We describe a rapid, high-throughput technique based on the ligation assay coupled with automated capillary fluorescence detection. This new approach allows the diagnosis of both Hgb S and Hgb C to be available in a few hours. We have utilized this technique in 30 prenatal diagnoses and found it to be in complete agreement with the standard diagnoses. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
695.
Francis J. Magilligan Patricia F. McDowell 《Journal of the American Water Resources Association》1997,33(4):867-878
ABSTRACT: Cattle grazing practices in the western United States have contributed to widespread riparian degradation resulting in unstable channel morphologies and the loss of fish habitat. Because of prolonged disturbance, numerous riparian areas on both public and private lands have been fenced to exclude cattle in order to promote vegetation establishment and riparian improvement. We selected four gravel-bedded, steep alluvial streams in eastern Oregon with cattle exclosures greater than 14 years old for an analysis of geomorphic adjustments following the removal of cattle grazing. We compare channels inside exclosures and in adjacent grazed reaches to identify the salient stream channel properties that respond to the removal of riparian stresses and to document the magnitude of these changes. Results indicate that significant changes occur, with reductions in bankfull dimensions and increases in pool area being the most common and identifiable changes. At all four sites, bankfull widths are narrower by 10 to 20 percent, and the percentage of channel area occupied by pools is higher in the exclosure by 8 to 15 percent. The increase in pool area is primarily offset by a reduction in the percent glide area. Not all of the channel properties demonstrate adjustment, indicating that perhaps 14 years is an insufficient duration for these variables to adjust. 相似文献
696.
The present study aimed to gather information on drug and alcohol use, the prevalence of drink and drug driving and attitudes to both in an undergraduate university cohort (n = 275). Further, the study aimed to contribute information to aid intervention program development by determining predictors of drink and drug driving behavior. The study examines both drug and alcohol use and the influence of attitudes toward driving while under the influence of alcohol and/or drugs. Results indicated that significant proportions of university students are engaging in the risk-taking behavior of driving under the influence of drugs (25%), alcohol (14%), or both (8%). The results suggest that attitudes toward driving under the influence of alcohol and/or drugs are a strong predictor of engaging in the behavior. Peer influence emerged as a major aspect of attitudes. The results of this study provide an important beginning to understanding drink and drug driving and the influence of attitudes in the university student body. 相似文献
697.
Davide?VioneEmail author Simone?Belmondo Lorenzo?Carnino 《Environmental Chemistry Letters》2004,2(3):135-139
We studied the transformation of phenol in the presence of nitrous acid in the dark. The main detected intermediates were 2-nitrophenol, 4-nitrophenol and 4-nitrosophenol. For the first time a kinetic analysis of the reaction in a pH interval relevant to environmental chemistry has been carried out. The kinetic data are consistent with phenol transformation being initiated by HNO2. The results are relevant to the chemistry of the atmosphere, where HNO2 forms upon heterogeneous conversion of ·NO2, and to water treatment techniques. 相似文献
698.
Waller PF 《Journal of Safety Research》2003,34(1):17-23
This paper discusses the early research that lead to graduated driver licensing, some of the educational principals on which it is based, obstacles to its acceptance, and some of the early efforts in the U.S. and elsewhere. EARLY RESEARCH: The research underlying the concept of graduated driver licensing was a 1971 North Carolina study that identified the overrepresentation of young drivers in crashes at night and when another young person was the right front passenger. EDUCATIONAL PRINCIPALS: Efforts to reduce the risk to young novice drivers applied what was known about learning. The concepts included distributed learning (i.e., over time) and progressing from simple to complex skills. A PROPOSAL: The proposed graduated licensing system based on learning principals included (a) initial experience under low risk conditions, (b) extended supervised practice, (c) gradual move to more complex conditions, and (d) harsher penalties for deliberate risk-taking. OBSTACLES: There were several most common objections raised against graduated licensing. Raising the licensing age decreased mobility. Some young drivers were "good" drivers. Enforcement is difficult. Fear of parental objections. Parents are not driver educators and some young people do not have an available parent. Administrative costs are too high. ACCEPTANCE: Driver educators were the first to see the benefits of a graduated system in the 1970s and 1980s. Toronto nearly adopted a graduated system in 1976. New Zealand was the first to adopt a graduated licensing system in 1984. Michigan in 1997 was the first state to require parental certification of extended supervised driving practice. 相似文献
699.
Dennis J. Kotchmar Thomas H. Stock Alfonso H. Holguin Patricia A. Buffler 《Environmental monitoring and assessment》1982,2(1-2):129-138
Procedures for determining exposure extimates for the Houston Area Asthma Study are discussed. Two residential clusters of asthmatics in the Houston area have been studied as part of an overall attempt to assess the health effects of air pollution in the Texas Gulf Coast area. Air pollutant exposure data have been produced according to a three-tier monitoring scheme, i.e. (1) continuous data from centrally-located fixed stations, (2) residential indoor/outdoor measurements, and (3) personal monitoring. This air monitoring network should yield estimates of individual exposures for use in health effect correlations.The fixed sites and mobile continuously monitor ambient levels of ozone, nitrogen oxides, sulfur dioxide, carbon monoxide, and meteorological parameters (wind speed, wind direction, temperature, dew point, solar irradiation, and precipitation). Continuous sequential integrated sampling is preformed for total suspended particulates (TSP) and, inhalable particulates (IP) (total of < 2.5m and 2.5–15.0 m) by dichotomous samplers for 24 hr samplers), aldehydes (bubblers), and aeroallergens (intermittent rotorod samplers). In addition to gravimetric determinations, particulate filters are routinely analyzed for sulfate, nitrate, and (every third day) trace elements. Personal monitoring includes ozone, respirable particles, nitrogen dioxide and formaldehyde. A quality assurance/control program that meets specifications established in the EPA Quality Assurance Handbook for air pollution measurement systems was implemented. Examples of results consisting of unvalidated preliminary data from the monitoring for ozone for three participants is presented and approaches to determining exposure estimates are discussed for both an integrated exposure estimate and short time period exposure estimate.(These studies have been funded by the U.S. Environmental Protection Agency through Cooperative Agreement CR 807108010 and Grant R 808738010. Statements made in this article should not be taken as Agency policy.) 相似文献
700.
Kevin A. Francesconi Patricia Micks Rodney A. Stockton Kurt J. Irgolic 《Chemosphere》1985,14(10):1443-1453
The major water-soluble arsenic compound in the Alaskan king crab, the Alaskan snow crab, and the Dungeness crab was identified as arsenobetaine by HPLC/ICP analysis. This technique is suitable for the identification and quantitative determination of naturally occurring organic arsenic compounds in purified and partially purified extracts from biota. 相似文献