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901.
(E)-6,10-dimethyl-5,9-undecadien-2-ol (geranyl acetol), termed here fuscol, was identified as a male-produced pheromone emitted
by Tetropium fuscum (F.) and Tetropium cinnamopterum Kirby. In field experiments, traps baited with synthetic fuscol alone were not significantly attractive, but the combination
of fuscol plus host volatiles (a synthetic blend of monoterpenes plus ethanol) attracted significantly more male and female
T. fuscum and female T. cinnamopterum than did host volatiles alone. This is the first homoterpenoid alcohol to be described in the Cerambycidae, and the first
pheromone reported from the sub-family Spondylidinae. 相似文献
902.
The fate of Norse farming settlements in southwest Greenland has often been seen as one of the great mysteries of North Atlantic colonization and expansion. Preservation of organic remains in the permafrost of the area of the Western Settlement, inland from the modern capital Nuuk, allowed very detailed study of the phases of occupation. Samples were taken from house floors and middens during the process of archaeological excavations and from insect remains were abstracted and identified in the laboratory. In this study, we present a new paleoecological approach principally examining the fossil fly faunas from house floors. The results of our study provide contrasting detailed pictures of the demise of two neighboring farms, Gården under Sandet and Nipaatsoq, one where abandonment appears as part of a normal process of site selection and desertion, and the other where the end was more traumatic. The level of detail, which was obtained by analysis of the dipterous (true fly) remains, exceeds all previous work and provides insights otherwise unobtainable. 相似文献
903.
904.
The continuing conundrum of the LEA proteins 总被引:9,自引:0,他引:9
Research into late embryogenesis abundant (LEA) proteins has been ongoing for more than 20 years but, although there is a strong association of LEA proteins with abiotic stress tolerance particularly dehydration and cold stress, for most of that time, their function has been entirely obscure. After their initial discovery in plant seeds, three major groups (numbered 1, 2 and 3) of LEA proteins have been described in a range of different plants and plant tissues. Homologues of groups 1 and 3 proteins have also been found in bacteria and in certain invertebrates. In this review, we present some new data, survey the biochemistry, biophysics and bioinformatics of the LEA proteins and highlight several possible functions. These include roles as antioxidants and as membrane and protein stabilisers during water stress, either by direct interaction or by acting as molecular shields. Along with other hydrophilic proteins and compatible solutes, LEA proteins might also serve as “space fillers” to prevent cellular collapse at low water activities. This multifunctional capacity of the LEA proteins is probably attributable in part to their structural plasticity, as they are largely lacking in secondary structure in the fully hydrated state, but can become more folded during water stress and/or through association with membrane surfaces. The challenge now facing researchers investigating these enigmatic proteins is to make sense of the various in vitro defined functions in the living cell: Are the LEA proteins truly multi-talented, or are they still just misunderstood? 相似文献
905.
PROBLEM: The purpose of this study was to examine the relationship between overall risk of injury and time use patterns between work and active recreation among adolescents and young adults. METHODS: Using a representative sample of 9,795 Canadians aged 15-24 years, a multivariate logistic regression on the likelihood of any medically attended injury was conducted, including sociodemographic, individual, and time factors. RESULTS: Young people who engaged in a combination of high work and high activity hours were twice as likely to sustain a medically attended injury compared to those who worked low hours, but did not participate in any recreational activity. Those respondents who were not in school had a 43% increase in injury risk compared to full-time students. SUMMARY: Our findings suggest that injury risk was not a simple function of fatigue and cumulative exposure time. Our findings suggest the importance of considering time use and the associated injury risk tradeoffs. IMPACT ON INDUSTRY: Relevant to state and federal work safety policy makers, our findings suggest the importance of understanding where youth might otherwise spend their time if constraint were placed on their employment opportunities, and the associated injury risk tradeoffs must be taken into consideration. 相似文献
906.
The existence of sex is one of the major unsolved problems in biology. We use computer simulations to model conditions in
which sex may first become established. We develop an individual-based population model and show that a hypothetical facultative
sex gene can fix, provided that the initial cost is low. It is demonstrated that the equilibrium fitness in the population
increases with increasing population size and decreasing mutation rate. The probability of the establishment of the sex gene
is found not to be directly related to the fitness difference between the asexual and sexual populations. This change in fitness
on changing the parameters of the model is investigated. 相似文献
907.
INTRODUCTION: This study evaluated the implementation of a second phase training program for novice drivers in Spain, which puts the primary focus of the training on the higher hierarchical levels of driver behavior. METHOD: Two hundred and sixty-three participants took part throughout the study, which was implemented as an experimental design with the test and control groups assessed before and after the one day safety training. Measurement of the impact of the training program focused on the participants' self-evaluation and self-reporting of some driving behavior indicators related to accident risk. RESULTS: Data analysis showed a change in the expected direction in the scale related to the skills for careful driving, but not for the other four scales considered. A feedback survey about the training course offered some important input for evaluating the organization, contents, tuition, and results of the three parts of the training program (discussion group, on-road and track training) as reported by the participants in the test group. CONCLUSIONS AND SUGGESTIONS: The results of the experiment show that using a one day driver safety course, it is possible to change some of the drivers' evaluations connected to safe driving style into safe direction. The follow-up period was exceptionally long (9 months) and the design (randomly divided experimental and control groups with before and after measurements) was reliable. More effort should be devoted to improving the on-road part of the training, which was often perceived as a typical driving lesson rather than a feedback drive. IMPACT ON INDUSTRY: The findings suggest consideration of a mandatory 2nd phase driver training programme as a means to raise awareness of the full range of risks encountered by novice drivers, and as already introduced in 5 EU countries: Austria, Estonia, Finland, Luxembourg and Switzerland. 相似文献
908.
Motor vehicle crashes killed almost 5,000 pedestrians in 2005 in the United States. Pedestrian risk may be higher in areas characterized by urban sprawl. From 2000 to 2004, pedestrian fatality rates declined in the United States, but the Atlanta metropolitan statistical area did not experience the same decline. Pedestrian fatality rates for males, Hispanics, and the 15–34 and 35–54 year age groups were higher in Atlanta than in the United States overall. Pedestrian safety interventions should be targeted to high-risk populations and localized pedestrian settings. 相似文献
909.
The double trade-off between adaptation and mitigation for sea level rise: an application of FUND 总被引:6,自引:2,他引:4
Richard S. J. Tol 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):741-753
This paper studies the effects of adaptation and mitigation on the impacts of sea level rise. Without adaptation, the impact
of sea level rise would be substantial, almost wiping out entire countries by 2100, although the globally aggregate effect
is much smaller. Adaptation would reduce potential impacts by a factor 10–100. Adaptation would come at a minor cost compared
to the damage avoided. As adaptation depends on socio-economic status, the rank order of most vulnerable countries is different
than the rank order of most exposed countries. Because the momentum of sea level rise is so large, mitigation can reduce impacts
only to a limited extent. Stabilising carbon dioxide concentrations at 550 ppm would cut impacts in 2100 by about 10%. However,
the costs of emission reduction lower the avoided impacts by up to 25% (average 10%). This is partly due to the reduced availability
of resources for adaptation, and partly due to the increased sensitivity to wetland loss by adaptation.
相似文献
Richard S. J. TolEmail: |
910.
In this study, landmark-based methods of geometric morphometrics are used for investigating the main aspects of cranial shape transformation in the evolution of the giant panda, Ailuropoda melanoleuca. Specifically, we explore if the highly derived cranial adaptations for bamboo feeding of the living panda were developed early in the panda's lineage. Results obtained show that the overall cranial morphologies of the oldest known panda, the "pygmy" Ailuropoda microta, and the late Pleistocene Ailuropoda baconi are both very similar to that of their closest living relative, A. melanoleuca, which agrees with a previous proposal based on qualitative criteria. However, we also describe several differences between the crania of A. microta, A. baconi, and A. melanoleuca, including the development of the postorbital process, the orientation of the occipital region, and the expansion of the braincase. As a result, the cranial morphology of A. microta shows a less specialized morphology toward a fibrous and durophagous diet compared to the giant panda. These results are confirmed by a comparative analysis of the dimensions of the upper teeth in bears, which has revealed differences in relative tooth size between A. microta and A. melanoleuca, most probably as a result of mosaic evolution. Therefore, we conclude that cranial shape did not remain essentially uniform in the Ailuropoda lineage, as previously thought, but underwent a number of changes during more than 2?Myr. 相似文献