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Inappropriate behavior during common handling procedures with horses is often subject to aversive treatment. The present study replicated and extended previous findings using differential reinforcement to shape appropriate equine handling behavior. In Study 1, a multiple baseline across subjects design was used with four horses to determine first the effects of shaping target-touch responses and then successive approximations of full truck loading under continuous and intermittent schedules of reinforcement. Full loading responses were shaped and maintained in all four horses and occurrences of inappropriate behaviors reduced to zero. Generalization of the loading response was also observed to both a novel trainer and trailer. In Study 2, a changing criterion design was used to increase the duration of feet handling with one horse. The horse's responding reached the terminal duration criterion of 1 min and showed consistent generalization and one-week maintenance. Overall, the results of both studies support the use of applied equine training systems based on positive reinforcement for increasing appropriate behavior during common handling procedures. 相似文献
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目的通过动态心电监护下心率变异性(HRV)分析自主神经功能对高血压病不同级别心功能不全的HRV变化。方法应用动态心电图和无创性心功能测定高血压病不同级别心功能不全的心率变异性的结果进行比较。结果发现高血压病不同级别心功能不全的患者随心功能损害的加重心率变异时域参数SDNN、SDRNN、RMSSD、PNN50和频域参数TP、VLF、LF、HF、LF/HF均明显降低,且有统计学差异。结论自主神经功能损害在高血压病不同级别的心功能不全患者起着重要的作用。 相似文献
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Molly A. Albecker Michael W. McCoy 《Evolution; international journal of organic evolution》2019,73(9):1941-1957
Organisms often respond to environmental change via phenotypic plasticity, in which an individual modulates its phenotype according to the environment. Highly variable or changing environments can exceed physiological limits and generate maladapted plastic phenotypes, which is termed nonadaptive plasticity. In some cases, selection may reduce the negative or disruptive impacts of environmental stress and produce locally adapted populations. Salt is an increasingly prevalent contaminant of freshwater systems and can induce nonadaptive plastic phenotypes for freshwater organisms like amphibians. Hyla cinerea is a frog species with populations inhabiting brackish, coastal habitats, so we use this species to test whether coastal populations are locally adapted to tolerate saltwater by determining how salt exposure during the embryonic and larval stages alters mortality and plastic developmental and metamorphic phenotypes of coastal and inland populations. Coastal frogs have higher survival, faster growth rates, and metamorphose sooner than inland frogs across salinities. Coastal frogs also metamorphose smaller (likely a consequence of earlier metamorphosis) yet maintain constant size, while higher salinities reduce metamorphic size for inland frogs. Coastal frogs evolved to minimize nonadaptive and disruptive impacts of saltwater during larval development and accelerate the larval period to reduce time spent in a stressful environment. 相似文献
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Summary We will discuss in which conditions we can expect the emergence of agents able to integrate sensory-motor information over
time and later use this information to modulate their behavior accordingly. In doing so we will illustrate the problems that
these agents should be able to solve and the processes that might lead to a transition from simple agents that only rely on
sensory information or on their internal dynamic to agents that are also able to integrate information over time. The analysis
of evolved individuals revealed that: (1) individuals able to integrate information over time rely on mixed strategy in which
basic sensory-motor mechanisms are complemented and enhanced with additional internal mechanisms; (2) evolved individuals
tend to rely on partial, action-oriented, and action-mediated representations of the external environment. 相似文献
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The multi-tier implementation has become the industry standard for developing scalable client-server enterprise applications.
Since these applications are performance sensitive, effective models for dynamic resource provisioning and for delivering
quality of service to these applications become critical. Workloads in such environments are characterized by client sessions
of interdependent requests with changing transaction mix and load over time, making model adaptivity to the observed workload
changes a critical requirement for model effectiveness. In this work, we apply a regression-based approximation of the CPU demand of client transactions on a given hardware. Then, we use this approximation in an analytic
model of a simple network of queues, each queue representing a tier, and show the approximation’s effectiveness for modeling
diverse workloads with a changing transaction mix over time. Using two case studies, we investigate factors that impact the
efficiency and accuracy of the proposed performance prediction models. Experimental results show that this regression-based approach provides a simple and powerful solution for efficient capacity planning and resource provisioning of multi-tier
applications under changing workload conditions.
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Qi ZhangEmail: |
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Luis‐Miguel Chevin Guillaume Decorzent Thomas Lenormand 《Evolution; international journal of organic evolution》2014,68(5):1244-1256
Niche dimensionality is suggested to be a key determinant of ecological speciation (“multifarious selection” hypothesis), but genetic aspects of this process have not been investigated theoretically. We use Fisher's geometrical model to study how niche dimensionality influences the mean fitness of hybrids formed upon secondary contact between populations adapting in allopatry. Gaussian selection for an optimum generates two forms of reproductive isolation (RI): an extrinsic component due to maladaptation of the mean phenotype, and an intrinsic variance load resulting from what we term transgressive incompatibilities between mutations fixed in different populations. We show that after adaptation to a new environment, RI increases with (1) the mean initial maladaptation of diverging population, and (2) niche dimensionality, which increases the phenotypic variability of fixed mutations. Under mutation selection drift equilibrium in a constant environment, RI accumulates steadily with time, at a rate that also increases with niche dimensionality. A similar pattern can be produced by successive shifts in the optimum phenotype. Niche dimensionality thus has an effect per se on postzygotic isolation, beyond putative indirect effects (stronger selection, more genes). Our mechanism is consistent with empirical evidence about transgressive segregation in crosses between divergent populations, and with patterns of accumulation of RI with time in many taxa. 相似文献