66 research outputs found

    Time series irreversibility: a visibility graph approach

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    We propose a method to measure real-valued time series irreversibility which combines two differ- ent tools: the horizontal visibility algorithm and the Kullback-Leibler divergence. This method maps a time series to a directed network according to a geometric criterion. The degree of irreversibility of the series is then estimated by the Kullback-Leibler divergence (i.e. the distinguishability) between the in and out degree distributions of the associated graph. The method is computationally effi- cient, does not require any ad hoc symbolization process, and naturally takes into account multiple scales. We find that the method correctly distinguishes between reversible and irreversible station- ary time series, including analytical and numerical studies of its performance for: (i) reversible stochastic processes (uncorrelated and Gaussian linearly correlated), (ii) irreversible stochastic pro- cesses (a discrete flashing ratchet in an asymmetric potential), (iii) reversible (conservative) and irreversible (dissipative) chaotic maps, and (iv) dissipative chaotic maps in the presence of noise. Two alternative graph functionals, the degree and the degree-degree distributions, can be used as the Kullback-Leibler divergence argument. The former is simpler and more intuitive and can be used as a benchmark, but in the case of an irreversible process with null net current, the degree-degree distribution has to be considered to identifiy the irreversible nature of the series.Comment: submitted for publicatio

    Physics demos for all UVEG degrees: a unique project in Spain

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    The Physics Demo Project at the University of Valencia (www.uv.es/fisicademos) has developed a collection of physics demonstrations to be used during lectures. It consists of more than 130 experimental demos about different physics topics. More than 30 professors borrow them whenever they lecture on physics in any of our 40 courses in 17 different science or technical degrees, involving 246 ECTS and more than 3500 students. Each demo kit with a simple experimental set displays a particular physics phenomenon. An on-line user guide highlights the main physics principles involved, instructions on how to use it and advices of how to link it to the theoretical concepts or to technical applications. Demo lectures (and collections) are a usual and widespread practice in many countries but not in Spain. This unique initiative aims at the recovery of this practice by involving a growing collaborative team of users and with the aid of educational innovation projects. Here we explain the project content, organization and recent developments. Our experience, together with the positive students comments, allows us to draw the following conclusions: demos introduce the real sensible world in the lecture hall, providing the necessary link between concepts and everyday life, and becoming, again, something more than "chalk and talk"

    Mindfulness-based program for anxiety and depression treatment in healthcare professionals: A pilot randomized controlled trial

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    In primary health care, the work environment can cause high levels of anxiety and depression, triggering relevant expert and individual change. Mindfulness-Based Stress Reduction (MBSR) programs reduce signs of anxiety and depression. The purpose of this sub-analysis of the total project, was to equate the effectiveness of the standard MBSR curriculum with the abbreviated version in minimizing anxiety and depression. This randomized controlled clinical trial enrolled 112 mentors and resident specialists from Family and Community Medicine and Nurses (FCMN), distributed across six teaching units (TU) of the Spanish National Health System (SNHS). Experimental group participants received a MBRS training (abbreviated/standard). Depression and anxiety levels were measured with the Goldberg Anxiety and Depression Scale (GADS) at three different time periods during the analysis: before (pre-test) and after (post-test) participation, as well as 3 months after the completion of intervention. Taking into account the pre-test scores as the covariate, an adjusted analysis of covariance (ANCOVA) showed significant depletion in anxiety and depression in general (F (2.91) = 4.488; p = 0.014; ¿2 = 0.090) and depression in particular (F (2, 91) = 6.653; p = 0.002; ¿2 = 0.128 at the post-test visit, maintaining their effects for 3 months (F (2.79) = 3.031; p = 0.050; ¿2 = 0.071—F (2.79) = 2.874; p = 0.049; ¿2 = 0.068, respectively), which is associated with the use of a standard training program. The abbreviated training program did not have a significant effect on the level of anxiety and depression. The standard MBSR training program had a positive effect on anxiety and depression and promotes long-lasting effects in tutors and resident practitioners. New research is needed to demonstrate the effectiveness of abbreviated versions of training programs. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Indirect search for dark matter: prospects for GLAST

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    Possible indirect detection of neutralino, through its gamma-ray annihilation product, by the forthcoming GLAST satellite from our galactic halo, M31, M87 and the dwarf galaxies Draco and Sagittarius is studied. Gamma-ray fluxes are evaluated for the two representative energy thresholds, 0.1 GeV and 1.0 GeV, at which the spatial resolution of GLAST varies considerably. Apart from dwarfs which are described either by a modified Plummer profile or by a tidally-truncated King profiles, fluxes are compared for halos with central cusps and cores. It is demonstrated that substructures, irrespective of their profiles, enhance the gamma-ray emission only marginally. The expected gamma-ray intensity above 1 GeV at high galactic latitudes is consistent with the residual emission derived from EGRET data if the density profile has a central core and the neutralino mass is less than 50 GeV, whereas for a central cusp only a substantial enhancement would explain the observations. From M31, the flux can be detected above 0.1 GeV and 1.0 GeV by GLAST only if the neutralino mass is below 300 GeV and if the density profile has a central cusp, case in which a significant boost in the gamma-ray emission is produced by the central black hole. For Sagittarius, the flux above 0.1 GeV is detectable by GLAST provided the neutralino mass is below 50 GeV. From M87 and Draco the fluxes are always below the sensitivity limit of GLAST.Comment: 14 Pages, 7 Figures, 3 Tables, version to appear on Physical Review

    Mindfulness in primary care healthcare and teaching professionals and its relationship with stress at work: a multicentric cross-sectional study

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    Background: Work stress is a common problem among the health personnel of the Spanish National Health System. The objective of this paper is to assess the state of mindfulness among Spanish primary care providers and to evaluate its potential relationship with work stress and basic labor and sociodemographic characteristics. Methods: Cross-sectional, multi-centric study. Primary care nurses, teachers, teaching collaborators and residents assigned to six Spanish Family Medicine/Family and Community Care Departments were invited to participate (n = 475). A template was designed in Google Forms, including sociodemographic and work-related variables. The state of mindfulness was measured with the Five Facet Mindfulness Questionnaire (FFMQ), while work-related stress was measured using an ordinal scale ranging from 0 to 10 points. Descriptive and inferential statistical analyses were carried out, as well as bivariate and multivariate statistics. Results: The mean age of participants was 40, 14 ± 13.12 (range:23–65 years); 66.9% were women, 42.5% internal medicine residents, 29.3% family physicians, and 20.2% nurses. More than half (54.5%) knew about mindfulness, with 24.0% have received training on it, and 22.5% were usual practitioners. The average level of mindfulness was 127.18 ± 15.45 (range: 89–177). The average score of stress at work was 6.00 ± 2.44; 49.9% (range: 0–10). 49.9% of participants scored 7 or more on the stress at work scale. There was an inverse correlation between the levels of mindfulness (FFMQ total score) and work-related stress (Spearman’s r = - 0.155, p = 0.003). Significant relationships between the mindfulness practice and the level of mindfulness (F = 29.80, p < 0.001), as well as between the mindfulness practice and the level of work-related stress (F = 9.68, p = 0.042), were also found. Conclusions: Levels of mindfulness in primary care health providers were in line with those levels observed in other groups of health professionals. Half of all of the primary care providers suffered from a high degree of stress. Although weak, inverse relationships were observed between levels of mindfulness and stress at work, with lower values of stress at work among those who practiced mindfulness. Trial registration: NCT03629457

    Impact of uterine manipulator on oncological outcome in endometrial cancer surgery

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    Background: There are limited data available to indicate whether oncological outcomes might be influenced by the uterine manipulator, which is used at the time of hysterectomy for minimally invasive surgery in patients with endometrial cancer. The current evidence derives from retrospective studies with limited sample sizes. Without substantial evidence to support its use, surgeons are required to make decisions about its use based only on their personal choice and surgical experience. Objective: To evaluate the use of the uterine manipulator on oncological outcomes after minimally invasive surgery, for apparent early-stage endometrial cancer. Study Design: We performed a retrospective multicentric study to assess the oncological safety of uterine manipulator use in patients with apparent early-stage endometrial cancer, treated with minimally invasive surgery. The type of manipulator, surgical staging, histology, lymphovascular space invasion, International Federation of Gynecology and Obstetrics stage, adjuvant treatment, recurrence, and pattern of recurrence were evaluated. The primary objective was to determine the relapse rate. The secondary objective was to determine recurrence-free survival, overall survival, and the pattern of recurrence. Results: A total of 2661 women from 15 centers were included; 1756 patients underwent hysterectomy with a uterine manipulator and 905 without it. Both groups were balanced with respect to histology, tumor grade, myometrial invasion, International Federation of Gynecology and Obstetrics stage, and adjuvant therapy. The rate of recurrence was 11.69% in the uterine manipulator group and 7.4% in the no-manipulator group (P<.001). The use of the uterine manipulator was associated with a higher risk of recurrence (hazard ratio, 2.31; 95% confidence interval, 1.27–4.20; P=.006). The use of uterine manipulator in uterus-confined endometrial cancer (International Federation of Gynecology and Obstetrics [FIGO] I–II) was associated with lower disease-free survival (hazard ratio, 1.74; 95% confidence interval, 0.57–0.97; P=.027) and higher risk of death (hazard ratio, 1.74; 95% confidence interval, 1.07–2.83; P=.026). No differences were found regarding the pattern of recurrence between both groups (chi-square statistic, 1.74; P=.63). Conclusion: In this study, the use of a uterine manipulator was associated with a worse oncological outcome in patients with uterus-confined endometrial cancer (International Federation of Gynecology and Obstetrics I–II) who underwent minimally invasive surgery. Prospective trials are essential to confirm these results

    One-step nucleic acid amplification (Osna) of sentinel lymph node in early-stage endometrial cancer: Spanish multicenter study (endo-osna)

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    The objective of this study was to evaluate the efficacy of one-step nucleic acid amplification (OSNA) for the detection of sentinel lymph node (SLN) metastasis compared to standard pathological ultrastaging in patients with early-stage endometrial cancer (EC). A total of 526 SLNs from 191 patients with EC were included in the study, and 379 SLNs (147 patients) were evaluated by both methods, OSNA and standard pathological ultrastaging. The central 1 mm portion of each lymph node was subjected to semi-serial sectioning at 200 µm intervals and examined by hematoxylin–eosin and immunohistochemistry with CK19; the remaining tissue was analyzed by OSNA for CK19 mRNA. The OSNA assay detected metastases in 19.7% of patients (14.9% micrometastasis and 4.8% macrometastasis), whereas pathological ultrastaging detected metastasis in 8.8% of patients (3.4% micrometastasis and 5.4% macrometastasis). Using the established cut-off value for detecting SLN metastasis by OSNA in EC (250 copies/µL), the sensitivity of the OSNA assay was 92%, specificity was 82%, diagnostic accuracy was 83%, and the negative predictive value was 99%. Discordant results between both methods were recorded in 20 patients (13.6%). OSNA resulted in an upstaging in 12 patients (8.2%). OSNA could aid in the identification of patients requiring adjuvant treatment at the time of diagnosis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Quantum walks: a comprehensive review

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    Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

    D* Production in Deep Inelastic Scattering at HERA

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    This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel D+(D0Kπ+)π+D^{*+}\to (D^0 \to K^- \pi^+) \pi^+ (+ c.c.) has been used in the study. The e+pe^+p cross section for inclusive D^{*\pm} production with 5<Q2<100GeV25<Q^2<100 GeV^2 and y<0.7y<0.7 is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {1.3<pT(D±)<9.01.3<p_T(D^{*\pm})<9.0 GeV and η(D±)<1.5| \eta(D^{*\pm}) |<1.5}. Differential cross sections as functions of p_T(D^{*\pm}), η(D±),W\eta(D^{*\pm}), W and Q2Q^2 are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and η\eta(D^{*\pm}), the charm contribution F2ccˉ(x,Q2)F_2^{c\bar{c}}(x,Q^2) to the proton structure function is determined for Bjorken xx between 2 \cdot 104^{-4} and 5 \cdot 103^{-3}.Comment: 17 pages including 4 figure
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