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81.
Internet photosharing websites is a very recent and powerful tool for the study of biodiversity, and a meeting point of general public fond of nature and professional naturalists. The article discusses when an uploaded picture is scientifically valuable, and the benefits of structured hosting websites for the most fruitful information retrieval. Examples are given of faunistic, biological, ecological and conservation results concerning Hemiptera provided by information download from photosharing websites.  相似文献   
82.
 Scleractinian coral reefs, when coexistent with siliciclastic sediments, usually occur in association with deltaic or coastal sands. Nevertheless, Pleistocene reef limestones in southwestern Taiwan are developed in association with thick claystones that were deposited in a deeper-water environment. These reef limestones are characterized by: (1) rapid transition from underlying claystones upward to reefal limestones, (2) lateral interfingering with open-shelf claystones, (3) being overlain by terrestrial deposits or exposed with no covering strata, and (4) being located in close association with anticlines. The authors propose that these reef limestones developed on anticlinal ridges raised above the adjacent sea floor by thrust-front migration in a foreland setting. Accepted: 21 April 1998  相似文献   
83.
Recknagel  Friedrich 《Hydrobiologia》1997,349(1-3):47-57
Predictive potential of deductive and inductivephytoplankton models are compared regarding theirusefulness for forecasting and control of harmfulalgal blooms. While applications of deductive modelsstill seem to be restricted by lack of knowledge, ad hocinductive models sometimes prove to bestraightforward and useful. The inductive neuralnetwork model ANNA is documented by means of anapplication to Lake Kasumigaura, Japan. ANNA wasvalidated for five blue-green algae species wherepredictive accuracy has improved with increased eventand time resolution of training data. A scenarioanalysis on species succession has demonstrated thepotential of ANNA for hypothesis testing. Finally,implications for use of ANNA for operational algalbloom control are discussed.  相似文献   
84.
The biological control service supplied to croplands is a result of the predator community present within a focal crop, which is likely influenced by surrounding landscape composition and configuration. In this study, using cage experiments in two regions near Santiago, we determined if predator communities supplied a significant biological control service in alfalfa fields, examined how the abundance of exotic and native coccinellids, as well as other key predator groups, influenced biological control of aphids and measured how landscape composition and heterogeneity at three spatial scales influenced this service. We found that predators significantly suppressed aphid populations in both regions, but the relative importance of predators versus landscape variables on biological control differed between regions. In the region where predators were abundant, biological control was higher and related to the abundance of native coccinellids and syrphids, highlighting the importance of native species as providers of crucial ecological services. In the region where predators were not abundant, biological control was lower, and it was related to landscape composition, being positively associated with the abundance of woodlots and urban habitats, and negatively associated with fruit crops in the landscape. Therefore, landscape effects on biological control service may be weaker than local factors, and only become important when local predator abundance is low.  相似文献   
85.
To understand the origin and genetic diversity of Italian horses, mitochondrial DNA D‐loop sequences were generated for 163 horses from seven breeds. Sequence analysis of a 480‐bp segment revealed a total of 84 haplotypes with 57 polymorphic sites, indicating multiple maternal origins and high genetic diversity. Comparison of the haplotypes with the equine mtDNA haplotype/haplogroup nomenclature showed a haplogroup distribution in the Italian breeds more similar to that found in the Middle East breeds than in the European breeds, probably due to the economic and cultural relationship with the Middle East in the past centuries.  相似文献   
86.
Waterhyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae), has been a global target for classical biological control efforts for decades. In Florida, herbicidal application is the primary control method employed, usually without regard for the activities of the three biological control agents introduced intentionally during the 1970s, namely Neochetina eichhorniae Warner, Neochetina bruchi, Hustache (Coleoptera: Curculionidae), and Niphograpta albiguttalis Warren (Lepidoptera: Crambidae). A series of field experiments from 2008 to 2010 was conducted at four Florida sites using an insecticide-check approach to quantify the current levels of suppression provided by these agents. In the field N. albiguttalis was rarely found while more than 99% of all Neochetina sp. adults were N. eichhorniae. Although it was not possible to disentangle the relative impacts of Neochetina sp. adults from larvae on individual plant variables, the larvae played a major role in reducing plant biomass and the number of inflorescences. Plots exposed to unrestricted herbivory contained 58.2% less biomass and produced 97.3% fewer inflorescences at the end of the experiments. Despite these large reductions, herbivory decreased waterhyacinth coverage by only 16.8% and most of this was attributed to a low-nutrient site where coverage was reduced disproportionately. Overall, coverage trended upwards during the course of the experiments and was always close to 100% when the plots were harvested. Although coverage is a somewhat arbitrary metric, especially for floating plants subject to compression and dispersion, it influences the perception of biological control efficacy which, in turn, directly influences herbicide management decisions in Florida. Despite waterhyacinth populations that now produce less than half as much biomass and up to 98% fewer seeds than before the deployment of biological control agents, the overall approach used to achieve maintenance control of the plant in Florida will probably not change unless new biological control agents, such as Megamelus scutellaris Berg (Hemiptera: Delphacidae), can reduce coverage significantly.  相似文献   
87.
Research examining the electromyographic (EMG) burst structure of rapid discrete limb movements has led to discordant findings concerning agonist burst duration. Some research has shown that duration varies as a function of movement speed while other research has shown burst constancy. Unfortunately, much of this research may be confounded by not carefully controlling movement termination accuracy and movement time (MT). Due to these potential problems, the present study was conducted to determine the effects of strict spatiotemporal constraints on EMG characteristics of a rapid elbow flexion-extension response under two movement extent conditions across five different MTs. Results revealed that a decreased MT was accompanied by a decreased agonist (biceps) burst duration and increased agonist burst amplitude. The burst duration and amplitude both increased as the movement extent increased with MT held constant. None of three current theoretical perspectives of rapid movement control (the impulse-timing model, the speed-control system hypothesis, or the speed-sensitive strategy) could fully account for these results. Instead, a control strategy was exhibited in which moving faster was accomplished by relative scaling of burst area via concomitant expansion of burst amplitude and compression of burst duration.  相似文献   
88.
89.
The pyrethroid insecticide lambda-cyhalothrin was evaluated in field trials against Glossina f.fuscipes and sleeping sickness transmission in Iyolwa sub-county, Tororo District, Uganda. The insecticide was applied selectively to the resting-sites of tsetse, by bush-spraying, using 10% wettable powder (10WP) formulation at an application rate of 11.6 g a.i./ha over an area of 28 km2, or by a 2% Electrodyn formulation (2ED) applied at 0.9 g a.i./ha over 30 km2. In a third trial area of 32 km2, 215 pyramidal traps treated with lambda-cyhalothrin 100 mg/m2 were set. The best impact was obtained with 10WP lambda-cyhalothrin which eliminated tsetse within 1-2 months, whereas G.f.fuscipes persisted at very low density in part of the area treated with 2ED lambda-cyhalothrin. In both treated areas the numbers of human sleeping sickness cases fell to no more than one per month, compared with four to twelve per month previously. The overall rate of cattle trypanosomiasis (T.brucei and T.vivax) was also reduced slightly. Insecticide-treated traps remained fully effective for at least 6 months under field conditions and catches were reduced 20-90-fold. These results in the control of tsetse and trypanosomiasis transmission lead us to recommend lambda-cyhalothrin for tsetse control operations.  相似文献   
90.
Musculoskeletal modeling allows for analysis of individual muscles in various situations. However, current techniques to realistically simulate muscle response when significant amounts of intentional coactivation is required are inadequate. This would include stiffening the neck or spine through muscle coactivation in preparation for perturbations or impacts. Muscle coactivation has been modeled previously in the neck and spine using optimization techniques that seek to maximize the joint stiffness by maximizing total muscle activation or muscle force. These approaches have not sought to replicate human response, but rather to explore the possible effects of active muscle. Coactivation remains a challenging feature to include in musculoskeletal models, and may be improved by extracting optimization objective functions from experimental data. However, the components of such an objective function must be known before fitting to experimental data. This study explores the effect of components in several objective functions, in order to recommend components to be used for fitting to experimental data. Four novel approaches to modeling coactivation through optimization techniques are presented, two of which produce greater levels of stiffness than previous techniques. Simulations were performed using OpenSim and MATLAB cooperatively. Results show that maximizing the moment generated by a particular muscle appears analogous to maximizing joint stiffness. The approach of optimizing for maximum moment generated by individual muscles may be a good candidate for developing objective functions that accurately simulate muscle coactivation in complex joints. This new approach will be the focus of future studies with human subjects.  相似文献   
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