2,562 research outputs found

    Carbohydrate-electrolyte drink ingestion and skill performance during and after 2 hr of indoor tennis match play

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    Twenty-two tennis players were individually studied on 2 occasions. They performed a prematch skill test, a 2-hr tennis match against an equally ranked opponent, and a postmatch skill test. A carbohydrate-electrolyte (CHO-E; Lucozade Sport) or flavor-matched placebo-electrolyte (PL) beverage was administered in a double-blind fashion. During the trials, heart-rate and movement intensity were monitored, and the match was recorded for performance analysis. There were no differences in skill-test scores pre- to postmatch or between trials (154 ± 38 pre- and 160 ± 35 postmatch on PL, 155 ± 36 pre- and 165 ± 33 postmatch on CHO-E). CHO-E ingestion elevated blood glucose concentration throughout the match, and participants reported feeling more energetic (general activation) and more tense (high activation) 1 hr into the match than at baseline (p less than .05). Participants in the CHO-E trial spent more time in moderate-intensity activity and less time in low-intensity activity than on PL. Performance analysis revealed that CHO-E ingestion increased overall serve success (M ± SD, 68% ± 7% for CHO-E vs. 66% ± 7% for PL; p less than .05) and success of first serves (65% ± 9% for CHO-E, 61% ± 7% for PL; p less than .01) and serves to the advantage side (70% ± 9% for CHO-E, 66% ± 7% for PL; p less than .05). Return success was greater during the second set of the match (p less than .05) in the CHO-E trial. Differences in serve and return success were not associated with blood glucose response to CHO or player abilit

    The Quantum Socket: Three-Dimensional Wiring for Extensible Quantum Computing

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    Quantum computing architectures are on the verge of scalability, a key requirement for the implementation of a universal quantum computer. The next stage in this quest is the realization of quantum error correction codes, which will mitigate the impact of faulty quantum information on a quantum computer. Architectures with ten or more quantum bits (qubits) have been realized using trapped ions and superconducting circuits. While these implementations are potentially scalable, true scalability will require systems engineering to combine quantum and classical hardware. One technology demanding imminent efforts is the realization of a suitable wiring method for the control and measurement of a large number of qubits. In this work, we introduce an interconnect solution for solid-state qubits: The quantum socket. The quantum socket fully exploits the third dimension to connect classical electronics to qubits with higher density and better performance than two-dimensional methods based on wire bonding. The quantum socket is based on spring-mounted micro wires the three-dimensional wires that push directly on a micro-fabricated chip, making electrical contact. A small wire cross section (~1 mmm), nearly non-magnetic components, and functionality at low temperatures make the quantum socket ideal to operate solid-state qubits. The wires have a coaxial geometry and operate over a frequency range from DC to 8 GHz, with a contact resistance of ~150 mohm, an impedance mismatch of ~10 ohm, and minimal crosstalk. As a proof of principle, we fabricated and used a quantum socket to measure superconducting resonators at a temperature of ~10 mK.Comment: Main: 31 pages, 19 figs., 8 tables, 8 apps.; suppl.: 4 pages, 5 figs. (HiRes figs. and movies on request). Submitte

    A counterfactual approach to measure the impact of wet grassland conservation on UK breeding bird populations

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    Wet grassland wader populations in the United Kingdom have experienced severe declines over the last three decades. To help mitigate these declines, the Royal Society for the Protection of Birds (RSPB) has restored and managed lowland wet grassland nature reserves to benefit these and other species. However, the impact that these reserves have on bird population trends has not been experimentally evaluated, as appropriate control populations do not readily exist. In this study, we compare population trends from 1994 ‐ 2018 for five bird species of conservation concern that breed on these nature reserves with counterfactual trends using matched breeding bird survey observations. Our results showed positive effects of conservation interventions for all four wader species that these reserves aim to benefit: Lapwing (Vanellus vanellus), Redshank (Tringa totanus), Curlew (Numenius arquata) and Snipe (Gallinago gallinago). There was no positive effect of conservation interventions on reserves for the passerine, Yellow Wagtail (Motacilla flava). We compared reserve trends with three different counterfactuals, based on different scenarios of how reserve populations could have developed in the absence of conservation, and found that reserve trends performed better regardless of the counterfactual used. Our approach using monitoring data to produce valid counterfactual controls is a broadly applicable method allowing large‐scale evaluation of conservation impact

    Universal Features in Phonological Neighbor Networks

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    Human speech perception involves transforming a countinuous acoustic signal into discrete linguistically meaningful units (phonemes) while simultaneously causing a listener to activate words that are similar to the spoken utterance and to each other. The Neighborhood Activation Model posits that phonological neighbors (two forms [words] that differ by one phoneme) compete significantly for recognition as a spoken word is heard. This definition of phonological similarity can be extended to an entire corpus of forms to produce a phonological neighbor network (PNN). We study PNNs for five languages: English, Spanish, French, Dutch, and German. Consistent with previous work, we find that the PNNs share a consistent set of topological features. Using an approach that generates random lexicons with increasing levels of phonological realism, we show that even random forms with minimal relationship to any real language, combined with only the empirical distribution of language-specific phonological form lengths, are sufficient to produce the topological properties observed in the real language PNNs. The resulting pseudo-PNNs are insensitive to the level of lingustic realism in the random lexicons but quite sensitive to the shape of the form length distribution. We therefore conclude that “universal” features seen across multiple languages are really string universals, not language universals, and arise primarily due to limitations in the kinds of networks generated by the one-step neighbor definition. Taken together, our results indicate that caution is warranted when linking the dynamics of human spoken word recognition to the topological properties of PNNs, and that the investigation of alternative similarity metrics for phonological forms should be a priorit

    Relativistic separable dual-space Gaussian Pseudopotentials from H to Rn

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    We generalize the concept of separable dual-space Gaussian pseudopotentials to the relativistic case. This allows us to construct this type of pseudopotential for the whole periodic table and we present a complete table of pseudopotential parameters for all the elements from H to Rn. The relativistic version of this pseudopotential retains all the advantages of its nonrelativistic version. It is separable by construction, it is optimal for integration on a real space grid, it is highly accurate and due to its analytic form it can be specified by a very small number of parameters. The accuracy of the pseudopotential is illustrated by an extensive series of molecular calculations

    Thermal conductivity and specific heat of the linear chain cuprate Sr2_{2}CuO3_{3}: Evidence for thermal transport via spinons

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    We report measurements of the specific heat and the thermal conductivity of the model Heisenberg spin-1/2 chain cuprate Sr2_{2}CuO3_{3} at low temperatures. In addition to a nearly isotropic phonon heat transport, we find a quasi one-dimensional excess thermal conductivity along the chain direction, most likely associated with spin excitations (spinons). The spinon energy current is limited mainly by scattering on defects and phonons. Analyzing the specific heat data, the intrachain magnetic exchange J/kBJ/k_{B} is estimated to be 2650 K.Comment: 4 RevTeX pages, 3 figures, to appear in Phys. Rev.

    Rehabilitating antisocial personalities: treatment through self-governance strategies

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    Offenders with antisocial personality disorder (ASPD) are widely assumed to reject psychotherapeutic intervention. Some commentators, therefore, argue that those with the disorder are better managed in the criminal justice system, where, following the introduction of indeterminate sentences, engagement with psychological treatment is coercively linked to the achievement of parole. By comparison, National Institute of Clinical Excellence guidelines on the management and treatment of ASPD recommend that those who are treatment seeking should be considered for admission to specialist psychiatric hospitals. The rationale is that prison-based interventions are underresourced, and the treatment of ASPD is underprioritised. The justification is that offenders with ASPD can be rehabilitated, if they are motivated. One problem, however, is that little is known about why offenders with ASPD seek treatment or what effect subsequent treatment has on their self-understanding. The aim of this paper is to address these unresolved issues. It draws on the findings of Economic and Social Research Council (ESRC) funded qualitative study examining the experiences of sentenced male offenders admitted to a specialist personality disorder ward within the medium secure estate and the medical practitioners who treat them. The data are analysed with reference to Michel Foucault’s work on governmentality and strategy in power relations. Two arguments are advanced: first, offenders with ASPD are motivated by legal coercive pressures to implement a variety of Foucauldian-type strategies to give the false impression of treatment progress. Second, and related, treatment does not result in changes in self-understanding in the resistive client with ASPD. This presupposes that, in respect of this group at least, Foucault was mistaken in his claim that resistive behaviours merely mask the effectiveness of treatment norms over time. Nevertheless, the paper concludes that specialist treatment in the hospital setting can effect changes in the resistive offender’s self-understanding, but not if the completion of treatment results, as is commonplace, in his prison readmission

    The storage capacity of Potts models for semantic memory retrieval

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    We introduce and analyze a minimal network model of semantic memory in the human brain. The model is a global associative memory structured as a collection of N local modules, each coding a feature, which can take S possible values, with a global sparseness a (the average fraction of features describing a concept). We show that, under optimal conditions, the number c of modules connected on average to a module can range widely between very sparse connectivity (c/N -> 0) and full connectivity (c = N), maintaining a global network storage capacity (the maximum number p of stored and retrievable concepts) that scales like c*S^2/a, with logarithmic corrections consistent with the constraint that each synapse may store up to a fraction of a bit.Comment: Accepted for publication in J-STAT, July 200

    Teleology and Realism in Leibniz's Philosophy of Science

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    This paper argues for an interpretation of Leibniz’s claim that physics requires both mechanical and teleological principles as a view regarding the interpretation of physical theories. Granting that Leibniz’s fundamental ontology remains non-physical, or mentalistic, it argues that teleological principles nevertheless ground a realist commitment about mechanical descriptions of phenomena. The empirical results of the new sciences, according to Leibniz, have genuine truth conditions: there is a fact of the matter about the regularities observed in experience. Taking this stance, however, requires bringing non-empirical reasons to bear upon mechanical causal claims. This paper first evaluates extant interpretations of Leibniz’s thesis that there are two realms in physics as describing parallel, self-sufficient sets of laws. It then examines Leibniz’s use of teleological principles to interpret scientific results in the context of his interventions in debates in seventeenth-century kinematic theory, and in the teaching of Copernicanism. Leibniz’s use of the principle of continuity and the principle of simplicity, for instance, reveal an underlying commitment to the truth-aptness, or approximate truth-aptness, of the new natural sciences. The paper concludes with a brief remark on the relation between metaphysics, theology, and physics in Leibniz
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