1,130 research outputs found

    Detailed Examination of Transport Coefficients in Cubic-Plus-Quartic Oscillator Chains

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    We examine the thermal conductivity and bulk viscosity of a one-dimensional (1D) chain of particles with cubic-plus-quartic interparticle potentials and no on-site potentials. This system is equivalent to the FPU-alpha beta system in a subset of its parameter space. We identify three distinct frequency regimes which we call the hydrodynamic regime, the perturbative regime and the collisionless regime. In the lowest frequency regime (the hydrodynamic regime) heat is transported ballistically by long wavelength sound modes. The model that we use to describe this behaviour predicts that as the frequency goes to zero the frequency dependent bulk viscosity and the frequency dependent thermal conductivity should diverge with the same power law dependence on frequency. Thus, we can define the bulk Prandtl number as the ratio of the bulk viscosity to the thermal conductivity (with suitable prefactors to render it dimensionless). This dimensionless ratio should approach a constant value as frequency goes to zero. We use mode-coupling theory to predict the zero frequency limit. Values of the bulk Prandtl number from simulations are in agreement with these predictions over a wide range of system parameters. In the middle frequency regime, which we call the perturbative regime, heat is transported by sound modes which are damped by four-phonon processes. We call the highest frequency regime the collisionless regime since at these frequencies the observing times are much shorter than the characteristic relaxation times of phonons. The perturbative and collisionless regimes are discussed in detail in the appendices.Comment: Latex with references in .bib file. 36 pages, 8 figures. Submitted to J. Stat. Phys. on Sept. 2

    Herausforderungen an der Schnittstelle Schule - Beruf: Beiträge zur Fachtagung "Wege ebnen an der Schnittstelle Schule - Beruf. Wie gelingt ein erfolgreicher Übergang?" vom 18. September 2013 in Wien

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    Aus dem Vorwort: "... Ziel dieser Veranstaltung, die am 18. September 2013 in der Zentrale der OeAD GmbH in Wien stattfand, war es, Stärken und Schwächen im Übergangsmanagement in Österreich auszuloten und bisherige gute Ansätze (Good Practices) in diesem Kontext aufzuzeigen. Die Veranstaltung gab zahlreichen PraktikerInnen, WissenschafterInnen und Verantwortlichen aus der bildungs- wie arbeitsmarktpolitischen Praxis die Möglichkeit, den Diskurs zu diesem Thema fortzuführen, neue Beiträge zu liefern und politischen Verbesserungsbedarf zu formulieren. Der vorliegend AMS report enthält die erweiterten Versionen ausgewählter Vorträge, die anlässlich dieser Tagung gehalten wurden. Die Veranstalter der Tagung, die OeAD GmbH - Nationalagentur Lebenslanges Lernen, die Abt. Arbeitsmarktforschung und Berufsinformation des AMS Österreich sowie das sozialwissenschaftliche Forschungsinstitut abif - Analyse, Beratung und interdisziplinäre Forschung bedanken sich bei allen TeilnehmerInnen dieser rege besuchten Veranstaltung und wünschen allen LeserInnen dieses AMS reports eine aufschlussreiche und interessante Lektüre. ...

    Spin polarization of the L-gap surface states on Au(111)

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    The electron spin polarization (ESP) of the L-gap surface states on Au(111) is investigated theoretically by means of first-principles electronic-structure and photoemission calculations. The surface states show a large spin-orbit induced in-plane ESP which is perpendicular to the in-plane wavevector, in close analogy to a two-dimensional electron gas with Rashba spin-orbit interaction. The surface corrugation leads to a small ESP component normal to the surface, being not reported so far. The surface-states ESP can be probed qualitatively and quantitatively by spin- and angle-resolved photoelectron spectroscopy, provided that the initial-state ESP is retained in the photoemission process and not obscured by spin-orbit induced polarization effects. Relativistic photoemission calculations provide detailed information on what photoemission set-ups allow to conclude from the photoelectron ESP on that of the surface states.Comment: 22 pages with 8 figure

    Anomalous heat conduction in one dimensional momentum-conserving systems

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    We show that for one dimensional systems with momentum conservation, the thermal conductivity κ\kappa generically diverges with system size as L1/3.L^{1/3}.Comment: 4 page

    Rapid enhancement of touch from non-informative vision of the hand

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    Processing in one sensory modality may modulate processing in another. Here we investigate how simply viewing the hand can influence the sense of touch. Previous studies showed that non-informative vision of the hand enhances tactile acuity, relative to viewing an object at the same location. However, it remains unclear whether this Visual Enhancement of Touch (VET) involves a phasic enhancement of tactile processing circuits triggered by the visual event of seeing the hand, or more prolonged, tonic neuroplastic changes, such as recruitment of additional cortical areas for tactile processing. We recorded somatosensory evoked potentials (SEPs) evoked by electrical stimulation of the right middle finger, both before and shortly after viewing either the right hand, or a neutral object presented via a mirror. Crucially, and unlike prior studies, our visual exposures were unpredictable and brief, in addition to being non-informative about touch. Viewing the hand, as opposed to viewing an object, enhanced tactile spatial discrimination measured using grating orientation judgements, and also the P50 SEP component, which has been linked to early somatosensory cortical processing. This was a trial-specific, phasic effect, occurring within a few seconds of each visual onset, rather than an accumulating, tonic effect. Thus, somatosensory cortical modulation can be triggered even by a brief, non-informative glimpse of one’s hand. Such rapid multisensory modulation reveals novel aspects of the specialised brain systems for functionally representing the body

    The use of Complementary and Alternative Medicine in pregnancy: Data from the Avon Longitudinal Study of Parents and Children (ALSPAC)

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    Objectives - To report the frequency of Complementary and Alternative Medicine (CAM) use by a population of pregnant women in the UK. Design - Four postal self-completion questionnaires completed at 8, 12, 18 and 32 weeks’ gestation provided the source of CAMs used. Questions asked for written descriptions about the use of any treatments, pills, medicines, ointments, homeopathic medicines, herbal medicines, supplements, drinks and herbal teas. Setting - An observational, population-based, cohort study of parents and children of 14,541 pregnant women residing within the former county of Avon in south-west England. Data was available for 14,115 women. Results - Over a quarter (26.7%; n = 3774) of women had used a CAM at least once in pregnancy, the use rising from 6% in the 1st trimester to 12.4% in the 2nd to 26.3% in the 3rd. Herbal teas were the most commonly reported CAM at any time in pregnancy (17.7%; n = 2499) followed by homeopathic medicine (14.4%; n = 2038) and then herbal medicine (5.8%; n = 813). The most commonly used herbal product was chamomile used by 14.6% of women, the most commonly used homeopathic product was Arnica used by 3.1% of women. Other CAMs (osteopathy, aromatherapy, acupuncture/acupressure, Chinese herbal medicine, chiropractic, cranial sacral therapy, hypnosis, non-specific massage and reflexology) accounted for less than 1% of users. Conclusions - CAM use in pregnancy, where a wide range of CAMs has been assessed, has not been widely reported. Studies that have been conducted report varying results to this study (26.7%) by between 13.3% and 87% of pregnant women. Survey results will be affected by a number of factors namely the inclusion/exclusion of vitamins and minerals, the timing of data collection, the country of source, the number of women surveyed, and the different selection criteria of either recruiting women to the study or of categorising and identifying a CAM treatment or product

    Herbal medicine use during pregnancy in a group of Australian women

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    BACKGROUND: There are limited data on the extent of women's use of herbal medicines during pregnancy, despite the fact that knowledge of the potential benefits or harms of many of these products is sparse, particularly with respect to their use in pregnancy. We aimed to measure the prevalence of herbal medicine use in a group of pregnant women attending a public tertiary maternity hospital in Melbourne, Australia. Secondary aims were to explore why women took the herbal medicine, where they received advice, what form the supplements took and if they perceived the supplements to be helpful. METHODS: Consecutive pregnant women were approached in the antenatal clinic and the birth centre at around 36–38 weeks gestation. A questionnaire was developed and self-administered in English, as well as being translated into the four most common languages of women attending the hospital: Cantonese, Vietnamese, Turkish and Arabic. Back translation into English was undertaken by different professional translators to verify accuracy of both words and concepts. Data collected included demographic information, model of pregnancy care and herbal supplement use. Descriptive statistics were used initially, with stratified and regression analysis to compare sub-groups. RESULTS: Of 705 eligible women, 588 (83%) agreed to participate. Of these, 88 (15%) completed the questionnaire in a language other than English. Thirty-six percent of women took at least one herbal supplement during the current pregnancy. The most common supplements taken were raspberry leaf (14%), ginger (12%) and chamomile (11%). Women were more likely to take herbal supplements if they were older, tertiary educated, English speaking, non-smokers and primiparous. CONCLUSION: Use of herbal supplements in pregnancy is likely to be relatively high and it is important to ascertain what supplements (if any) women are taking. Pregnancy care providers should be aware of the common herbal supplements used by women, and of the evidence regarding potential benefits or harm

    Brownian motion: a paradigm of soft matter and biological physics

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    This is a pedagogical introduction to Brownian motion on the occasion of the 100th anniversary of Einstein's 1905 paper on the subject. After briefly reviewing Einstein's work in its contemporary context, we pursue some lines of further developments and applications in soft condensed matter and biology. Over the last century Brownian motion became promoted from an odd curiosity of marginal scientific interest to a guiding theme pervading all of the modern (live) sciences.Comment: 30 pages, revie

    Jowett’s Thucydides: A corpus-based analysis of translation as political intervention

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    Thucydides’ History of the Peloponnesian War is a key text in the classical Greek canon and an important source of insights into the structures and tensions at the heart of ancient Athenian democracy. Consequently, modern interpretations of his analysis have repeatedly played a major role in shaping debates on the viability and desirability of democratic rule. This paper aims to build on previous discussion of Benjamin Jowett's 1881 translation of Thucydides by applying a comparative corpus-based methodology to explore how this translator's own personal politics shaped his re-presentation of this text. The analysis reveals a striking emphasis on the position and activity of democratic leaders throughout Jowett’s version, strongly consistent with the ideology of leadership that he developed during his career as Master of Balliol College, Oxford
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