737 research outputs found

    Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement

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    The influence of a transverse electric field in the specific heat of triglycine sulphate (TGS) has been studied. The specific heat of TGS has been measured heating the sample from ferroelectric to paraelectric phase after prolonged transverse electric field (i.e. perpendicular to the ferroelectric axis). It is shown that the specific heat of TGS can remember the temperature TsT_s at which the transverse field was previously applied.Comment: ReVTeX4 Twocolumn 4 pages, 4 figure

    Avalanche criticality in the martensitic transition of Cu67.64Zn16.71Al15.65 shape-memory alloy: a calorimetric and acoustic emission study

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    The first-order diffusionless structural transition in Cu67.64Zn16.71Al15.65 is characterized by jerky propagation of phase fronts related to the appearance of avalanches. In this paper, we describe a full analysis of this avalanche behavior using calorimetric heat-flux measurements and acoustic emission measurements. Two different propagation modes, namely, smooth front propagation and jerky avalanches, were observed in extremely slow measurements with heating and cooling rates as low as a few 10−3 K/h. Avalanches show criticality where each avalanche leads to a spike in the heat flux. Their statistical analysis leads to a power law [P(E)∼E−ε, where P(E)dE is the probability to observe an avalanche with energy E in an interval between E and E+dE] with an energy exponent of ε=2.15±0.15 in excellent agreement with the results of acoustic emission measurements. Avalanches appear to be more common for heating rates faster than 5×10−3 K/h whereas smooth front propagation occurs in all calorimetric measurements and (almost) exclusively for slower heating rates. Repeated cooling runs were taken after a waiting time of 1 month (and an intermediate heating run). Correlations between the avalanche sequences of the two cooling runs were found for the strongest avalanche peaks but not for the full sequence of avalanches. The memory effect is hence limited to strong avalanches

    The order parameter-entropy relation in some universal classes: experimental evidence

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    The asymptotic behaviour near phase transitions can be suitably characterized by the scaling of Δs/Q2\Delta s/Q^2 with ϵ=1T/Tc\epsilon=1-T/T_c, where Δs\Delta s is the excess entropy and QQ is the order parameter. As Δs\Delta s is obtained by integration of the experimental excess specific heat of the transition Δc\Delta c, it displays little experimental noise so that the curve log(Δs/Q2)\log(\Delta s/Q^2) versus logϵ\log\epsilon is better constrained than, say, logΔc\log\Delta c versus logϵ\log\epsilon. The behaviour of Δs/Q2\Delta s/Q^2 for different universality classes is presented and compared. In all cases, it clearly deviates from being a constant. The determination of this function can then be an effective method to distinguish asymptotic critical behaviour. For comparison, experimental data for three very different systems, Rb2CoF4, Rb2ZnCl4 and SrTiO3, are analysed under this approach. In SrTiO3, the function Δs/Q2\Delta s/Q^2 does not deviate within experimental resolution from a straight line so that, although Q can be fitted with a non mean-field exponent, the data can be explained by a classical Landau mean-field behaviour. In contrast, the behaviour of Δs/Q2\Delta s/Q^2 for the antiferromagnetic transition in Rb2CoF4 and the normal-incommensurate phase transition in Rb2ZCl4 is fully consistent with the asymptotic critical behaviour of the universality class corresponding to each case. This analysis supports, therefore, the claim that incommensurate phase transitions in general, and the A2_2BX4_4 compounds in particular, in contrast with most structural phase transitions, have critical regions large enough to be observable.Comment: 13 pp. 9 ff. 2 tab. RevTeX. Submitted to J. Phys.: Cond. Matte

    Aligning the principles of assessment for learning to learning in physical education: a review of literature

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    peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 19/04/2022Background: A comprehensive international literature review on alternative assessment in physical education has been provided by López-Pastor et al. ([2013]. “Alternative Assessment in Physical Education: A Review of International Literature.” Sport, Education & Society 18 (1): 57–76). The authors remarked that while more authentic forms of assessment in physical education have been evidenced over the last three decades, the extent to which alternative assessment practices have become common practice in the teaching of physical education is yet to be established. Purpose: This review provides an updated perspective on the prevalence of assessment for learning (AfL) principles in physical education discourse since the 2013 publication. The intent is to inform and consider future AfL practices in school physical education and physical education teacher education (PETE) programmes. Methods: Eligibility criteria for the review required full-text articles written in English or Spanish; published (open access and/or in print) in peer-reviewed, academic and professional journals; and limited to the period 2013–2019. Inclusion criteria required articles to report assessment being used to promote learning in physical education, regardless of making reference to ‘assessment for learning’. Findings: Fifty-two articles met the inclusion criteria. A thematic analysis of these articles resulted in four themes: i) traditional positioning of assessment in physical education; ii) AfL and physical education; iii) the constraints in enacting AfL in physical education; and iv) how to most effectively embed AfL in daily physical education practices. Conclusions: The main conclusions of this review are that i) AfL is a learning-oriented assessment based on socio constructivist theories and integrated into the teaching-learning process, ii) physical education teachers continue to use assessment solely to grade students; iii) physical education teachers do not have the necessary skillset to use AfL in physical education successfully; iv) physical education teachers need to be supported to implement AfL; and v) it is necessary to consider how best PETE programmes can infuse AfL across the programme

    CONTROL VIRTUAL DE UN COMPUTADOR MEDIANTE EL SENSOR KINECT

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     Este trabajo presenta la interacción entre el Sensor Kinect y un computador, permitiendo al usuario controlar programas de Windows por medio de gestos, sin necesidad de usar un dispositivo, donde “el control eres tú”. Para el desarrollo del presente trabajo se realiza el rastreo de ciertas partes del cuerpo permitiendo al usuario manipular el ordenador depen- diendo de sus necesidades. En esta aplicación se utiliza dos funcionalidades del sensor Kinect; la cámara de profundidad y skeleton tracking, esto se efectuó utilizando una programación orientada a objetos en Visual Studio 2010 (C#, WPF). Se realizó pruebas experimentales en las cuales se comprobó el desempeño de la propuesta.  Palabras clave: Sensor Kinect, skeleton tracking, programaión orientada a objetos.  ABSTRACT:  This work presents the interaction between the Kinect Sensor and a computer, allowing the user to control Windows programs through gestures without using any devices, where “you are the control”. For the development of this work certain body parts where tracked which allows the user to manipulate the computer depending on their needs. Two of the functionalities of the Kinect sensor are used in this application; the depth camera and skeleton tracking. This was done using Visual Studio 2010 (C#, WPF) object oriented programming. Experimental tests were done with which the performance of the proposal was validated.  Keywords: Kinect sensor, skeleton tracking, object oriented programmin

    PrevenBox: Evaluation of concomitant use of preventive medications with OnabotulinumtoxinA in migraine

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    P114 Background: OnabotulinumtoxinA is an effective, tolerable and safepreventive treatment for chronic migraine (CM). Other than a reduc-tion in headache frequency or disability, in CM the withdrawal ofconcomitant preventive medication indicates treatment effectivenessand quality of life improvement. Objective: To characterize the change in the use of oral preventivemedication after treatment with OnabotulinumtoxinA in patientswith migraine. Methods: This is a multicentre study. We consecutively included pa-tients with migraine (ICHD-3) that were on preventive treatment withOnabotulinumtoxinA. We retrospectively collected demographic data, diagnosis of migraine, frequency and intensity changes, number ofcycle and OnabotulinumtoxinA dose. In addition, we listed the initialand current preventive treatment (number of drugs and group) andthe number and cycle of medications withdrawn. We performed aunivariate and logistic regression analysis. Results: We included 542 patients: 87.6% women, mean age 47.6 ±11.7 years. A 89.3% had chronic migraine and 10.8% had high fre-quency episodic migraine. The mean reduction in frequency aftertreatment was 13.4±8.2 headache days/month. At baseline, a 91.3%took other preventives and during treatment with Onabotulinumtox-inA a 58.6% withdrew at least one drug, 25.8% stopped completelyall oral preventive drugs. Factors associated with withdrawal were:being male, having >50% response in frequency and intensity, thenumber of infiltrations and a shorter chronification period until thefirst OnabotulinumtoxinA administration (p <0.05). The multivariateanalysis showed that a better response in intensity (OR:1.8 [1.4-2.2], p<0.001), a greater number of infiltrations (OR:1.1 [1.0-1.2], p<0.001)and a shorter chronification period (OR:0.994 [0.992-0.997], p<0.001)were predictors of withdrawal. The ROC curve, showed that 6 Onabo-tulinumtoxinA cycles was the cut-off point that better predicted oralpreventive medication withdrawal (p <0.001). Conclusions: Treatment with OnabotulinumtoxinA reduces the use ofother preventive medications for migraine. The highest probability ofwithdrawal occurs after 6 cycles of treatment

    Preclinical Pharmacokinetic Evaluation to Facilitate Repurposing of Tyrosine Kinase Inhibitors Nilotinib and Imatinib as Antiviral Agents

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    Background Several tyrosine kinase inhibitors (TKIs) developed as anti-cancer drugs, also have anti-viral activity due to their ability to disrupt productive replication and dissemination in infected cells. Consequently, such drugs are attractive candidates for “repurposing” as anti-viral agents. However, clinical evaluation of therapeutics against infectious agents associated with high mortality, but low or infrequent incidence, is often unfeasible. The United States Food and Drug Administration formulated the “Animal Rule” to facilitate use of validated animal models for conducting anti-viral efficacy studies. Methods To enable such efficacy studies of two clinically approved TKIs, nilotinib, and imatinib, we first conducted comprehensive pharmacokinetic (PK) studies in relevant rodent and non-rodent animal models. PK of these agents following intravenous and oral dosing were evaluated in C57BL/6 mice, prairie dogs, guinea pigs and Cynomolgus monkeys. Plasma samples were analyzed using an LC-MS/MS method. Secondarily, we evaluated the utility of allometry-based inter-species scaling derived from previously published data to predict the PK parameters, systemic clearance (CL) and the steady state volume of distribution (Vss) of these two drugs in prairie dogs, an animal model not tested thus far. Results Marked inter-species variability in PK parameters and resulting oral bioavailability was observed. In general, elimination half-lives of these agents in mice and guinea pigs were much shorter (1–3 h) relative to those in larger species such as prairie dogs and monkeys. The longer nilotinib elimination half-life in prairie dogs (i.v., 6.5 h and oral, 7.5 h), facilitated multiple dosing PK and safety assessment. The allometry-based predicted values of the Vss and CL were within 2.0 and 2.5-fold, respectively, of the observed values. Conclusions Our results suggest that prairie dogs and monkeys may be suitable rodent and non-rodent species to perform further efficacy testing of these TKIs against orthopoxvirus infections. The use of rodent models such as C57BL/6 mice and guinea pigs for assessing pre-clinical anti-viral efficacy of these two TKIs may be limited due to short elimination and/or low oral bioavailability. Allometry-based correlations, derived from existing literature data, may provide initial estimates, which may serve as a useful guide for pre-clinical PK studies in untested animal models

    Assessing Monkeypox Virus Prevalence in Small Mammals at the Human-Animal Interface in the Democratic Republic of the Congo

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    During 2012, 2013 and 2015, we collected small mammals within 25 km of the town of Boende in Tshuapa Province, the Democratic Republic of the Congo. The prevalence of monkeypox virus (MPXV) in this area is unknown; however, cases of human infection were previously confirmed near these collection sites. Samples were collected from 353 mammals (rodents, shrews, pangolins, elephant shrews, a potamogale, and a hyrax). Some rodents and shrews were captured from houses where human monkeypox cases have recently been identified, but most were trapped in forests and agricultural areas near villages. Real-time PCR and ELISA were used to assess evidence of MPXV infection and other Orthopoxvirus (OPXV) infections in these small mammals. Seven (2.0%) of these animal samples were found to be anti-orthopoxvirus immunoglobulin G (IgG) antibody positive (six rodents: two Funisciurus spp.; one Graphiurus lorraineus; one Cricetomys emini; one Heliosciurus sp.; one Oenomys hypoxanthus, and one elephant shrew Petrodromus tetradactylus); no individuals were found positive in PCR-based assays. These results suggest that a variety of animals can be infected with OPXVs, and that epidemiology studies and educational campaigns should focus on animals that people are regularly contacting, including larger rodents used as protein sources

    <i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

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    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

    Detection of North American orthopoxviruses by real time-PCR

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    The prevalence of North American orthopoxviruses in nature is unknown and may be more difficult to ascertain due to wide spread use of vaccinia virus recombinant vaccines in the wild. A real time PCR assay was developed to allow for highly sensitive and specific detection of North American orthopoxvirus DNA in animal tissues and bodily fluids. This method is based on the amplification of a 156 bp sequence within a myristylated protein, highly conserved within the North American orthopoxviruses but distinct from orthologous genes present in other orthopoxviruses. The analytical sensitivity was 1.1 fg for Volepox virus DNA, 1.99 fg for Skunkpox virus DNA, and 6.4 fg for Raccoonpox virus DNA with a 95% confidence interval. Our assay did not cross-react with other orthopoxviruses or ten diverse representatives of the Chordopoxvirinae subfamily. This new assay showed more sensitivity than tissue culture tests, and was capable of differentiating North American orthopoxviruses from other members of Orthopoxvirus. Thus, our assay is a promising tool for highly sensitive and specific detection of North American orthopoxviruses in the United States and abroad
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