140 research outputs found

    Dwight Davis and the Foundation of the Davis Cup in Tennis: Just another Doubleday Myth?

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    Dwight F. Davis is widely credited with having invented, or at least conceived, the original idea for the international tennis competition that bears his name, the Davis Cup. This paper aims to debunk this myth through comprehensive critical analysis of the period preceding Davis's apparent epiphany in 1899. Previous national-team-based competitions are investigated, alongside key figures in American and British/Irish tennis, to demonstrate that numerous others had proposed the idea for an international team-based competition long before Davis and that Davis may have appropriated his idea from others with whom he came into contact. Davis's wealthy background, political ambitions, and model-American image arguably helped smooth the process of his idea being officially accepted by the United States National Lawn Tennis Association, which likely saw in Davis a perfect "frontman" for American tennis at a time when the nation used sporting prowess to promote its identity, particularly in relation to the British, in international sporting competitio

    Physiological function and catalytic versatility of bacterial multihaem cytochromescinvolved in nitrogen and sulfur cycling

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    Bacterial MCCs (multihaem cytochromes c) represent widespread respiratory electron-transfer proteins. In addition, some of them convert substrates such as nitrite, hydroxylamine, nitric oxide, hydrazine, sulfite, thiosulfate or hydrogen peroxide. In many cases, only a single function is assigned to a specific MCC in database entries despite the fact that an MCC may accept various substrates, thus making it a multifunctional catalyst that can play diverse physiological roles in bacterial respiration, detoxification and stress defence mechanisms. The present article briefly reviews the structure, function and biogenesis of selected MCCs that catalyse key reactions in the biogeochemical nitrogen and sulfur cycles

    Room temperature electroluminescence from mechanically formed van der Waals III–VI homojunctions and heterojunctions

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    Room temperature electroluminescence from semiconductor junctions is demonstrated. The junctions are fabricated by the exfoliation and direct mechanical adhesion of InSe and GaSe van der Waals layered crystals. Homojunction diodes formed from layers of p- and n-type InSe exhibit electroluminescence at energies close to the bandgap energy of InSe (Eg= 1.26 eV). In contrast, heterojunction diodes formed by combining layers of p-type GaSe and n-type InSe emit photons at lower energies, which is attributed to the generation of spatially indirect excitons and a staggered valence band lineup for the holes at the GaSe/InSe interface. These results demonstrate the technological potential of mechanically formed heterojunctions and homojunctions of direct-bandgap layered GaSe and InSe compounds with an optical response over an extended wavelength range, from the near-infrared to the visible spectrum

    Ligand-induced control of photoconductive gain and doping in a hybrid graphene-quantum dot transistor

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    In graphene devices decorated with a layer of near-infrared colloidal PbS quantum dots (QDs), the choice of the QD capping ligands and the integrity of the QD layer have a strong influence on the doping, carrier mobility, and photoresponse. By using short (<1 nm) capping ligands, the photoresponsivity of the graphene devices is enhanced up to 109 A W−1

    Ligand-induced control of photoconductive gain and doping in a hybrid graphene-quantum dot transistor

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    In graphene devices decorated with a layer of near-infrared colloidal PbS quantum dots (QDs), the choice of the QD capping ligands and the integrity of the QD layer have a strong influence on the doping, carrier mobility, and photoresponse. By using short (<1 nm) capping ligands, the photoresponsivity of the graphene devices is enhanced up to 109 A W−1

    High broad-band photoresponsivity of mechanically formed InSe-graphene van der Waals heterostructures

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    We exploit the broad-band transparency of graphene and the favorable band line up of graphene with van der Waals InSe crystals to create new functional heterostructures and high-performance photodetectors. The InSe-graphene heterostructure exhibits a high photoresponsivity, which exceeds that for other two-dimensional van der Waals crystals, and a spectral response that extends from the near-infrared to the visible spectrum. The highest photoresponsivity is achieved in device architectures where the InSe and graphene layers are vertically stacked, thus enabling effective extraction of photogenerated carriers from the InSe to the graphene electrodes

    Generic properties of the complementarity problem

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    Given f : R + n → R n , the complementarity problem is to find a solution to x ≥ 0, f(x) ≥ 0, and 〈 x, f(x) 〉 = 0. Under the condition that f is continuously differentiable, we prove that for a generic set of such an f , the problem has a discrete solution set. Also, under a set of generic nondegeneracy conditions and a condition that implies existence, we prove that the problem has an odd number of solutions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47915/1/10107_2005_Article_BF01584674.pd

    A time-motion analysis of paralympic football for athletes with cerebral palsy

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    To investigate the soccer match-play work of players with cerebral palsy, 40 elite players were monitored for cardiovascular and locomotive demands of tournament match play. Using global positioning satellite and heart rate monitors, total distance travelled, distance travelled at high intensity and very high intensity (m); frequency of high intensity and very high intensity activity; heart rate. Disability classes C5/6, C7 and C8 were compared. The results showed C8 players covered the greatest distance. Frequency, contribution and maximum speed of high intensity and very high intensity activity was greater in C8. There was a progressive decline in distances covered in all classes across match quarters. C8 spent more time above 85% HRmax. No differences were observed between C5/6 and C7 classes. In conclusion, C8 players most notably perform best in very high intensity activity associated with game-defining moments. C5/6 and C7 players performed equitably. This study is the first to provide an insight for practitioners and coaches interested in the work rates in soccer for athletes with cerebral palsy
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