57,283 research outputs found

    Producing a commentary slows concurrent hazard perception responses

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    Commentary driver training involves teaching drivers how to verbally acknowledge their perceptual and cognitive processes while driving, and has been shown to improve performance in driving-related tasks. However, those studies demonstrating benefits of commentary training have not done so under conditions of live commentary, which is the typical protocol used with advanced drivers. In the current study we present the results of two experiments that show that producing a commentary can actually slow responses to hazards on a concurrent hazard perception task. In Experiment 1 participants producing a live commentary showed significantly longer hazard response times than an untrained, silent, control group. In Experiment 2 a shorter, clipped commentary was introduced to attempt to reduce the demands placed upon participants. However, both the clipped and full commentary conditions showed reduced accuracy and longer response times, relative to a silent condition, and no difference was observed between the two types of commentary. Analysis of eye movements in both experiments revealed that fixation durations were shorter when a commentary was produced, but time to first fixate the hazard was not affected. This suggests that commentaries encourage more active interrogation of the visual scene, but that this can be detrimental to performance in average drivers

    Spectral Action for Robertson-Walker metrics

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    We use the Euler-Maclaurin formula and the Feynman-Kac formula to extend our previous method of computation of the spectral action based on the Poisson summation formula. We show how to compute directly the spectral action for the general case of Robertson-Walker metrics. We check the terms of the expansion up to a_6 against the known universal formulas of Gilkey and compute the expansion up to a_{10} using our direct method

    Double point contact in Quantum Hall Line Junctions

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    We show that multiple point contacts on a barrier separating two laterally coupled quantum Hall fluids induce Aharonov-Bohm (AB) oscillations in the tunneling conductance. These quantum coherence effects provide new evidence for the Luttinger liquid behavior of the edge states of quantum Hall fluids. For a two point contact, we identify coherent and incoherent regimes determined by the relative magnitude of their separation and the temperature. We analyze both regimes in the strong and weak tunneling amplitude limits as well as their temperature dependence. We find that the tunneling conductance should exhibit AB oscillations in the coherent regime, both at strong and weak tunneling amplitude with the same period but with different functional form.Comment: 4 pages, 3 figures; new version, edited text, 2 new references; figure 2 has been edited; new paragraph in page 1 and minor typos have been correcte

    Automated design of robust discriminant analysis classifier for foot pressure lesions using kinematic data

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    In the recent years, the use of motion tracking systems for acquisition of functional biomechanical gait data, has received increasing interest due to the richness and accuracy of the measured kinematic information. However, costs frequently restrict the number of subjects employed, and this makes the dimensionality of the collected data far higher than the available samples. This paper applies discriminant analysis algorithms to the classification of patients with different types of foot lesions, in order to establish an association between foot motion and lesion formation. With primary attention to small sample size situations, we compare different types of Bayesian classifiers and evaluate their performance with various dimensionality reduction techniques for feature extraction, as well as search methods for selection of raw kinematic variables. Finally, we propose a novel integrated method which fine-tunes the classifier parameters and selects the most relevant kinematic variables simultaneously. Performance comparisons are using robust resampling techniques such as Bootstrap632+632+and k-fold cross-validation. Results from experimentations with lesion subjects suffering from pathological plantar hyperkeratosis, show that the proposed method can lead tosim96sim 96%correct classification rates with less than 10% of the original features

    Escaping Antiangiogenic Therapy: Strategies Employed by Cancer Cells

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    Indexación: Web of ScienceTumor angiogenesis is widely recognized as one of the hallmarks of cancer. Consequently, during the last decades the development and testing of commercial angiogenic inhibitors has been a central focus for both basic and clinical cancer research. While antiangiogenic drugs are now incorporated into standard clinical practice, as with all cancer therapies, tumors can eventually become resistant by employing a variety of strategies to receive nutrients and oxygen in the event of therapeutic assault. Herein, we concentrate and review in detail three of the principal mechanisms of antiangiogenic therapy escape: (1) upregulation of compensatory/alternative pathways for angiogenesis; (2) vasculogenic mimicry; and (3) vessel co-option. We suggest that an understanding of how a cancer cell adapts to antiangiogenic therapy may also parallel the mechanisms employed in the bourgeoning tumor and isolated metastatic cells delivering responsible for residual disease. Finally, we speculate on strategies to adapt antiangiogenic therapy for future clinical uses.http://www.mdpi.com/1422-0067/17/9/148

    Interference of nematic quantum critical quasiparticles: a route to the octet model

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    Repeated observations of inhomogeneity in cuperate superconductors[1-5] make one immediately question the existance of coherent quasiparticles(qp's) and the applicability of a momentum space picture. Yet, obversations of interference effects[6-9] suggest that the qp's maintain a remarkable coherence under special circumstances. In particular, quasi-particle interference (QPI) imaging using scanning tunneling spectroscopy revealed a highly unusual form of coherence: accumulation of coherence only at special points in momentum space with a particular energy dispersion[5-7]. Here we show that nematic quantum critical fluctuations[10], combined with the known extreme velocity anisotropy[11] provide a natural mechanism for the accumulation of coherence at those special points. Our results raise the intriguing question of whether the nematic fluctuations provide the unique mechanism for such a phenomenon.Comment: 4 pages, 3 figure

    Signatures of unconventional pairing in near-vortex electronic structure of LiFeAs

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    A major question in Fe-based superconductors remains the structure of the pairing, in particular whether it is of unconventional nature. The electronic structure near vortices can serve as a platform for phase-sensitive measurements to answer this question. By solving Bogoliubov-de Gennes equations for LiFeAs, we calculate the energy-dependent local electronic structure near a vortex for different nodeless gap-structure possibilities. At low energies, the local density of states (LDOS) around a vortex is determined by the normal-state electronic structure. However, at energies closer to the gap value, the LDOS can distinguish an anisotropic from a conventional isotropic s-wave gap. We show within our self-consistent calculation that in addition, the local gap profile differs between a conventional and an unconventional pairing. We explain this through admixing of a secondary order parameter within Ginzburg-Landau theory. In-field scanning tunneling spectroscopy near vortices can therefore be used as a real-space probe of the gap structure

    Testosterone: Bad for Men, Good for Women?

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    # The Author(s) 2010. This article is published with open access at Springerlink.com Generally, high testosterone levels within the physiological range are associated with a more favourable cardiometabolic profile. Although the FDA has approved testosterone for use only in men with hypogonadism, whose sex glands produce extremely low amounts of testosterone, off-label use has dramatically increased in recent years. In the past two decades, there has been a huge increase in testosterone prescriptions, and many trials have shown benefit in terms of risk factor modification and symptoms. These observations fit also into the picture that reduced testosterone levels in men are associated with increased cardiovascular risk inducing elevated triglyceride levels, low high-density lipoprotein (HDL) cholesterol levels, central obesity, glucose intolerance, and diabetes. This has recently been demonstrated by Malkin et al. (October 26 issue, 2010, Heart), who showed that low testosterone levels (total testosterone <8.1 nmol/l) are associated with early death in men with heart disease. The longitudinal follow-up study involved 930 men with coronary heart disease for a period of about 7 years. During the study period, 41 of 194 (21%) men with low testosterone levels died compared with 88 of 736 (12%) men with normal levels of the hormone (p=0.002). It was concluded that, if androgen deficiency is part of the underlying pathophysiology of atherosclerotic disease in men, the serum testosterone level could be viewed as a favourable modifiable risk factor. However, this view has been challenged by Basaria et al

    Spectral density analysis of the interface in stratified oil-water flows

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    In this work the wavy interface of stratified oil-water flows was investigated using wire conductance probes. The experiments were carried out in a 38mm ID acrylic pipe using water and oil (Exxsol D140 oil: ρ=830kgm, μ=0.0055kgms) as test fluids. High-speed imaging revealed that almost two-dimensional interfacial waves develop at the inlet junction for input oil-to-water flow rate ratios different from one. Downstream the inlet section, however, the interface has a complex three dimensional structure with very small amplitude contributions. The structure of such interfaces can be properly investigated from the power spectrum of the conductance probe signal. A rigorous and detailed methodology is presented for estimating the power spectrum of the interface signal that is based on the Wiener-Khinchine theorem and makes extensive use of a Fast Fourier Transform (FFT) algorithm. Interface spectra were studied at two locations, close to the inlet of the test section and at 7m downstream. The results showed that the waves at the inlet have a unique peak frequency of about 19Hz and that, at the downstream location, this frequency is still present but has a smaller significance compared to that caused by the mechanical vibrations of the set up. This frequency was independent of the flow rates and could be a characteristic of the pair of the test fluids used rather than of the flow. © 2014 The Authors
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