989 research outputs found

    Corticospinal output and loss of force during motor fatigue

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    The objective of this study was to analyze central motor output changes in relation to contraction force during motor fatigue. The triple stimulation technique (TST, Magistris et al. in Brain 121(Pt 3):437-450, 1998) was used to quantify a central conduction index (CCI=amplitude ratio of central conduction response and peripheral nerve response, obtained simultaneously by the TST). The CCI removes effects of peripheral fatigue from the quantification. It allows a quantification of the percentage of the entire target muscle motor unit pool driven to discharge by a transcranial magnetic stimulus. Subjects (n=23) performed repetitive maximal voluntary contractions (MVC) of abductor digiti minimi (duration 1s, frequency 0.5Hz) during 2min. TST recordings were obtained every 15s, using stimulation intensities sufficient to stimulate all cortical motor neurons (MNs) leading to the target muscle, and during voluntary contractions of 20% of the MVC to facilitate the responses. TST was also repetitively recorded during recovery. This basic exercise protocol was modified in a number of experiments to further characterize influences on CCI of motor fatigue (4min exercise at 50% MVC; delayed fatigue recovery during local hemostasis, "stimulated exercise” by 20Hz trains of 1s duration at 0.5Hz during 2min). In addition, the cortical silent period was measured during the basic exercise protocol. Force fatigued to approximately 40% of MVC in all experiments and in all subjects. In all subjects, CCI decreased during exercise, but this decrease varied markedly between subjects. On average, CCI reductions preceded force reductions during exercise, and CCI recovery preceded force recovery. Exercising at 50% for 4min reduced muscle force more markedly than CCI. Hemostasis induced by a cuff delayed muscle force recovery, but not CCI recovery. Stimulated exercise reduced force markedly, but CCI decreased only marginally. Summarized, force reduction and reduction of the CCI related poorly quantitatively and in time, and voluntary drive was particularly critical to reduce the CCI. The fatigue induced reduction of CCI may result from a central inhibitory phenomenon. Voluntary muscle activation is critical for the CCI reduction, suggesting a primarily supraspinal mechanis

    Parameterized thermal macromodeling for fast and effective design of electronic components and systems

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    We present a parameterized macromodeling approach to perform fast and effective dynamic thermal simulations of electronic components and systems where key design parameters vary. A decomposition of the frequency-domain data samples of the thermal impedance matrix is proposed to improve the accuracy of the model and reduce the number of the computationally costly thermal simulations needed to build the macromodel. The methodology is successfully applied to analyze the impact of layout variations on the dynamic thermal behavior of a state-of-the-art 8-finger AlGaN/GaN HEMT grown on a SiC substrate

    Willingness to pay for a local food label for lamb meat in Spain

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    The aim of the paper is to assess consumers’ willingness to pay (WTP) for a local food produced in a less-favoured area in the Aragon region (Spain). In particular, we examine whether consumers value lamb meat products (lamb and suckling lamb) labelled as “Ojinegra from Teruel”, traditionally produced in these area. We use a nonhypothetical experimental auction to elicit Spanish consumers’ WTP for “Ojinegra from Teruel” labelled lamb products. Results show that consumers are willing to pay a positive premium for a lamb and suckling lamb labelled as “Ojinegra from Teruel

    On the use of honesty priming task to mitigate hypothetical bias in choice experiments

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    We test whether the use of an honesty priming task from the social psychology literature can help mitigate hypothetical bias in stated preference choice experiments (CE). Using a between-sample design, we conducted experiments with five treatments: (1) hypothetical CE without cognitive task, (2) hypothetical CE with cheap talk script, (3) hypothetical CE with neutral priming task, (4) hypothetical CE with honesty priming task, and (5) non-hypothetical CE. Results generally suggest that marginal willingness to pay estimates from treatment 4 where subjects are given honesty priming task before the choice experiment are not statistically different from marginal valuations from treatment 5 where subjects are in a non-hypothetical choice experiment. Values from both these treatments are significantly lower than those from other three hypothetical treatments (treatments 1-3). Using hold out tasks, our results also suggest that one could get higher correct predictions of participants’ choices in treatments 4 and 5 than in treatments 1-3 and that there is no significant difference in percentage of correct predictions between treatments 4 and

    Importance of Social Influence in Consumers' Willingness to Pay for Local Food: Are There Gender Differences?

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    The authors assess consumers' willingness to pay (WTP) for a local food product using an experimental auction. As local foods involve a social component, they aim also to test if social influence affects WTP for local foods and if the effects of social influence on WTP are different between men and women. They found that consumers are willing to pay a premium for the analyzed local food product. Moreover, social influence indeed affects WTP values, but the effects are different between men and women. Although social influence positively affects WTP for local foods for women, the effect is negative for men. The results have significant marketing and policy implications related to the promotion of local foods.Peer Reviewedexperimental auctionlabellamb meatSpainwillingness to payPublishe

    FLUKA simulations for the optimization of the Beam Loss Monitors

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    The collimation system in the beam cleaning insertion IR7 of the Large Hadron Collider (LHC) is expected to clean the primary halo and the secondary radiation of a beam with unprecedented energy and intensity. Accidental beam losses can therefore entail severe consequences to the hardware of the machine. Thus, protection mechanisms, e.g. beam abort, must be instantaneously triggered by a set of Beam Loss Monitors (BLM's). The readings in the BLM's couple the losses from various collimators, thus rendering the identification of any faulty unit rather complex. In the present study the detailed geometry of IR7 is upgraded with the insertion of the BLM's, and the Monte Carlo FLUKA transport code is used to estimate the individual contribution of every collimator to the showers detected in each BLM

    Participants’ competitiveness and bidding behaviour in experimental auctions: an application to the Spanish market

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    The aim of the paper was to examine if experimental auctions are demand revealing regardless the level of participants’ competitiveness. Then, we design an experimental auction with two treatments to check if the level of participants’ competitiveness does affect their bidding behavior. Both treatments had all the same designed characteristics except that in the second treatment, participants who reported the highest levels of competitiveness were not allow to participate in the auction. Then, we could directly compare bids from both treatments to test differences in bidding behavior between them. Our findings generally indicate that the level of participants’ competitiveness does not affect bidding behavior and then, homegrown experimental auctions are demand revealing in practice regardless the level of participants’ competitiveness.demand revelationlamb meatSpainOjinegra from TeruelPublishe
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