478 research outputs found

    Notes on the value function approach to multiobjective bilevel optimization

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    This paper is concerned with the value function approach to multiobjective bilevel optimization which exploits a lower level frontier-type mapping in order to replace the hierarchical model of two interdependent multiobjective optimization problems by a single-level multiobjective optimization problem. As a starting point, different value-function-type reformulations are suggested and their relations are discussed. Here, we focus on the situations where the lower level problem is solved up to efficiency or weak efficiency, and an intermediate solution concept is suggested as well. We study the graph-closedness of the associated efficiency-type and frontier-type mappings. These findings are then used for two purposes. First, we investigate existence results in multiobjective bilevel optimization. Second, for the derivation of necessary optimality conditions via the value function approach, it is inherent to differentiate frontier-type mappings in a generalized way. Here, we are concerned with the computation of upper coderivative estimates for the frontier-type mapping associated with the setting where the lower level problem is solved up to weak efficiency. We proceed in two ways, relying, on the one hand, on a weak domination property and, on the other hand, on a scalarization approach. Throughout the paper, illustrative examples visualize our findings, the necessity of crucial assumptions, and some flaws in the related literature.Comment: 30 page

    Acroneuria lycorias (Boreal Stonefly, Plecoptera: Perlidae) Emergence Behaviors Discovered in Pinus strobus Canopy

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    Species of Plecoptera, or stoneflies, are known to use vertical emergence supports, and researchers believe many species of Plecoptera exploit arboreal habitats during emergence. However, the exact nature of these arboreal behaviors has largely remained a mystery. While exploring the habitat potential of Pinus strobus (L.) (Eastern White Pine) canopies in northern Wisconsin we observed Acroneuria lycorias (Newman) (Boreal Stonefly, Plecoptera: Perlidae) exuviae at heights as high as 12m (observations at 6.6, 9, 9.5, and 12m). Most A. lycorias exuviae appeared to have a strong preference for emergence sites at the underside or base of branches similar to some Odonate species. We also observed A. lycorias, adults climbing upwards along the main stem, post-emergence, to heights up to 22m. To our knowledge, these heights represent the greatest heights ever documented for A. lycorias adults and exuviae, or any Plecopteran species. While other researchers have speculated that A. lycorias uses arboreal habitats during emergence, these behaviors were considered almost impossible to describe. Our observations provide us with new insights into Plecopteran emergence behaviors, especially for this species. We propose three alternative hypotheses that may explain these unique emergence behaviors

    No Overt Effects of a 6-Week Exergame Training on Sensorimotor and Cognitive Function in Older Adults. A Preliminary Investigation

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    Several studies investigating the relationship between physical activity and cognition showed that exercise interventions might have beneficial effects on working memory, executive functions as well as motor fitness in old adults. Recently, movement based video games (exergames) have been introduced to have the capability to improve cognitive function in older adults. Healthy aging is associated with a loss of cognitive, as well as sensorimotor functions. During exergaming, participants are required to perform physical activities while being simultaneously surrounded by a cognitively challenging environment. However, only little is known about the impact of exergame training interventions on a broad range of motor, sensory, and cognitive skills. Therefore, the present study aims at investigating the effects of an exergame training over 6 weeks on cognitive, motor, and sensory functions in healthy old participants. For this purpose, 30 neurologically healthy older adults were randomly assigned to either an experimental (ETG, n = 15, 1 h training, twice a week) or a control group (NTG, n = 15, no training). Several cognitive tests were performed before and after exergaming in order to capture potential training-induced effects on processing speed as well as on executive functions. To measure the impact of exergaming on sensorimotor performance, a test battery consisting of pinch and grip force of the hand, tactile acuity, eye-hand coordination, flexibility, reaction time, coordination, and static balance were additionally performed. While we observed significant improvements in the trained exergame (mainly in tasks that required a high load of coordinative abilities), these gains did not result in differential performance improvements when comparing ETG and NTG. The only exergaming- induced difference was a superior behavioral gain in fine motor skills of the left hand in ETG compared to NTG. In an exploratory analysis, within-group comparison revealed improvements in sensorimotor and cognitive tasks (ETG) while NTG only showed an improvement in a static balance test. Taken together, the present study indicates that even though exergames might improve gaming performance, our behavioral assessment was probably not sensitive enough to capture exergaming-induced improvements. Hence, we suggest to use more tailored outcome measures in future studies to assess potential exergaming- induced changes

    Acroneuria lycorias (Boreal Stonefly, Plecoptera: Perlidae) Emergence Behaviors Discovered in Pinus strobus Canopy

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    Species of Plecoptera, or stoneflies, are known to use vertical emergence supports, and researchers believe many species of Plecoptera exploit arboreal habitats during emergence. However, the exact nature of these arboreal behaviors has largely remained a mystery. While exploring the habitat potential of Pinus strobus (L.) (Eastern White Pine) canopies in northern Wisconsin we observed Acroneuria lycorias (Newman) (Boreal Stonefly, Plecoptera: Perlidae) exuviae at heights as high as 12m (observations at 6.6, 9, 9.5, and 12m). Most A. lycorias exuviae appeared to have a strong preference for emergence sites at the underside or base of branches similar to some Odonate species. We also observed A. lycorias, adults climbing upwards along the main stem, post-emergence, to heights up to 22m. To our knowledge, these heights represent the greatest heights ever documented for A. lycorias adults and exuviae, or any Plecopteran species. While other researchers have speculated that A. lycorias uses arboreal habitats during emergence, these behaviors were considered almost impossible to describe. Our observations provide us with new insights into Plecopteran emergence behaviors, especially for this species. We propose three alternative hypotheses that may explain these unique emergence behaviors

    Monitoring and Modeling of Emissions from Concentrated Animal Feeding Operations: Overview of Methods

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    Accurate monitors are required to determine ambient concentration levels of contaminants emanating from concentrated animal feeding operations (CAFOs), and accurate models are required to indicate the spatial variability of concentrations over regions affected by CAFOs. A thorough understanding of the spatial and temporal variability of concentration levels could then be associated with locations of healthy individuals or subjects with respiratory ailments to statistically link the presence of CAFOs to the prevalence of ill health effects in local populations. This workgroup report, which was part of the Conference on Environmental Health Impacts of Concentrated Animal Feeding Operations: Anticipating Hazards—Searching for Solutions, describes instrumentation currently available for assessing contaminant concentration levels in the vicinity of CAFOs and reviews plume dispersion models that may be used to estimate concentration levels spatially. Recommendations for further research with respect to ambient air monitoring include accurately determining long-term average concentrations for a region under the influence of CAFO emissions using a combination of instruments based on accuracy, cost, and sampling duration. In addition, development of instruments capable of accurately quantifying adsorbed gases and volatile organic compounds is needed. Further research with respect to plume dispersion models includes identifying and validating the most applicable model for use in predicting downwind concentrations from CAFOs. Additional data are needed to obtain reliable emission rates from CAFOs

    FLEXIBILIDADE: FACILITAÇÃO NEUROMUSCULAR PROPRIOCEPTIVA EM ATLETAS DE KARATÊ

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    Pode-se dizer, que a prática da modalidade de karatê trás inúmeros benefícios para as crianças e jovens, sempre com o devido acompanhamento de profissionais especializados. O objetivo do estágio foi de propor uma ação multidisciplinar para aumentar a capacidade de amplitude do movimento dos praticantes, e consequentemente, melhorar os déficits motores dos alunos, tornando-os aptos para a execução precisa das técnicas do karatê, bem como a aplicação correta dos exercícios, evitando assim quaisquer possíveis lesões. Para a realização dos exercícios foi utilizado apenas a academia e um tatame posto no local. Pelo fato do público alvo ser crianças que se apresentam em fase de crescimento, e a maioria iniciante no esporte, foram elaborados exercícios de baixa complexidade, atendendo ao objetivo principal, a flexibilidade (amplitude do movimento). Apliquei os exercícios visando os membros inferiores, utilizando o método de Facilitação Neuromuscular Proprioceptiva (FNP, método 3s). As duas turmas demonstraram interesse nos exercícios propostos e obtiveram um bom entendimento do exercício, o que possibilitou um ótimo andamento das aulas. Os resultados não foram tão perceptíveis, contudo, pude notar outros resultados como a socialização e colaboração entre os alunos, o aumento da atenção e concentração, e ainda, da memória, pois a cada aula os alunos deveriam recordar todos os movimentos. Verificou-se que houve aprendizagem sobre a valência flexibilidade, bem como, a evidente experiência adquirida dentro da área, o que contribuirá muito para a minha formação profissional

    Lack of Immediate Effects on Excitation and Interhemispheric Inhibition of the Human Motor Cortex

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    Transcranial alternating current stimulation (tACS) is a form of noninvasive brain stimulation and is capable of influencing brain oscillations and cortical networks. In humans, the endogenous oscillation frequency in sensorimotor areas peaks at 20 Hz. This beta-band typically occurs during maintenance of tonic motor output and seems to play a role in interhemispheric coordination of movements. Previous studies showed that tACS applied in specific frequency bands over primary motor cortex (M1) or the visual cortex modulates cortical excitability within the stimulated hemisphere. However, the particular impact remains controversial because effects of tACS were shown to be frequency, duration and location specific. Furthermore, the potential of tACS to modulate cortical interhemispheric processing, like interhemispheric inhibition (IHI), remains elusive. Transcranial magnetic stimulation (TMS) is a noninvasive and well-tolerated method of directly activating neurons in superficial areas of the human brain and thereby a useful tool for evaluating the functional state of motor pathways. The aim of the present study was to elucidate the immediate effect of 10 min tACS in the β-frequency band (20 Hz) over left M1 on IHI between M1s in 19 young, healthy, right-handed participants. A series of TMS measurements (motor evoked potential (MEP) size, resting motor threshold (RMT), IHI from left to right M1 and vice versa) was performed before and immediately after tACS or sham using a double-blinded, cross-over design. We did not find any significant tACS-induced modulations of intracortical excitation (as assessed by MEP size and RMT) and/or IHI. These results indicate that 10 min of 20 Hz tACS over left M1 seems incapable of modulating immediate brain activity or inhibition. Further studies are needed to elucidate potential aftereffects of 20 Hz tACS as well as frequency- specific effects of tACS on intracortical excitation and IHI

    Echo Spectroscopy of Atomic Dynamics in a Gaussian Trap via Phase Imprints

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    We report on the collapse and revival of Ramsey fringe visibility when a spatially dependent phase is imprinted in the coherences of a trapped ensemble of two-level atoms. The phase is imprinted via the light shift from a Gaussian laser beam which couples the dynamics of internal and external degrees of freedom for the atoms in an echo spectroscopy sequence. The observed revivals are directly linked to the oscillatory motion of atoms in the trap. An understanding of the effect is important for quantum state engineering of trapped atoms
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