536 research outputs found

    Anisotropic thermal emission from magnetized neutron stars

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    The thermal emission from isolated neutron stars is not well understood. The X-ray spectrum is very close to a blackbody but there is a systematic optical excess flux with respect to the extrapolation to low energy of the best blackbody fit. This fact, in combination with the observed pulsations in the X-ray flux, can be explained by anisotropies in the surface temperature distribution.We study the thermal emission from neutron stars with strong magnetic fields in order to explain the origin of the anisotropy. We find (numerically) stationary solutions in axial symmetry of the heat transportequations in the neutron star crust and the condensed envelope. The anisotropy in the conductivity tensor is included consistently. The presence of magnetic fields of the expected strength leads to anisotropy in the surface temperature. Models with toroidal components similar to or larger than the poloidal field reproduce qualitatively the observed spectral properties and variability of isolated neutron stars. Our models also predict spectral features at energies between 0.2 and 0.6 keV.Comment: 18 pages, 19 figures, version accepted for publication in A&

    3D reconstruction of medical images from slices automatically landmarked with growing neural models

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    In this study, we utilise a novel approach to segment out the ventricular system in a series of high resolution T1-weighted MR images. We present a brain ventricles fast reconstruction method. The method is based on the processing of brain sections and establishing a fixed number of landmarks onto those sections to reconstruct the ventricles 3D surface. Automated landmark extraction is accomplished through the use of the self-organising network, the growing neural gas (GNG), which is able to topographically map the low dimensionality of the network to the high dimensionality of the contour manifold without requiring a priori knowledge of the input space structure. Moreover, our GNG landmark method is tolerant to noise and eliminates outliers. Our method accelerates the classical surface reconstruction and filtering processes. The proposed method offers higher accuracy compared to methods with similar efficiency as Voxel Grid

    Diagnostic criteria for bipolarity based on an international sample of 5,635 patients with DSM-IV major depressive episodes

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    To assess the clinical validity of individual DSM-IV criteria for hypomania. In an international sample of 5,635 patients with major depressive episodes (Bridge Study), DSM-IV criteria for hypomania (stem questions, number and quality of symptoms, duration and exclusion criteria) were systematically assessed and their validity analysed on the basis of clinical data including family history, course, and other clinical characteristics. Three stem questions for hypomania, irritability, elevated mood and the added question of increased activity, showed comparable validity. The results support the current DSM-IV requirement for a higher symptom threshold (4 of 7 hypomanic symptoms) in cases of irritable mood. Longer durations of hypomanic episodes were associated with higher scores on all validators. The results did not support the DSM-IV durational requirements for hypomanic episodes (4days) and manic episodes (7days). Brief hypomanic episodes of 1, 2 or 3days were valid and would meet validity criteria for inclusion. The three exclusion criteria in DSM-IV (hypomania due to the use of antidepressants or of other substances, or to other medical conditions) were found to exclude patients with bipolar depression and should therefore not be retained. These results support several revisions of the DSM-IV concept of hypomanic episodes: specifically, the inclusion of increased activity as a gate question, the inclusion of 1 or 2 to 3-day episodes and the elimination of all exclusion criteri

    Real time motion estimation using a neural architecture implemented on GPUs

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    This work describes a neural network based architecture that represents and estimates object motion in videos. This architecture addresses multiple computer vision tasks such as image segmentation, object representation or characterization, motion analysis and tracking. The use of a neural network architecture allows for the simultaneous estimation of global and local motion and the representation of deformable objects. This architecture also avoids the problem of finding corresponding features while tracking moving objects. Due to the parallel nature of neural networks, the architecture has been implemented on GPUs that allows the system to meet a set of requirements such as: time constraints management, robustness, high processing speed and re-configurability. Experiments are presented that demonstrate the validity of our architecture to solve problems of mobile agents tracking and motion analysis

    The holy grail:Environmental management, competitive advantage and business performance in the Spanish hotel industry

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    © Emerald Group Publishing Limited G959-6119. Purpose - This paper aims to analyse the influence of environmental proactivity on cost and differentiation competitive advantages, and to explore the double relationship between environmental proactivity and business performance. Design/methodology/approach - The population consists of all three- to five-star hotels in Spain. A sample of 350 hotels was classified according to environmental proactivity and performance levels, employing a two-step cluster analysis. Significant differences between groups were examined. Findings - The results show two types of environmental behaviour (reactive and proactive), with proactive hotels developing significantly better on both cost and differentiation competitive advantage and achieving significantly higher performance levels. Hotels which achieve above average business performance levels are significantly more environmentally proactive. Research limitations/implications - The present paper demonstrates that environmental management is related to competitive advantages and business performance. Environmental management systems are more developed in higher category, chain-affiliated and larger hotels. This could be due to having more resources to develop their environmental capability. The environmental proactivity scale employed in this study is presented as a reference measure for hotel managers to benchmark their current practices and implement environmental improvements. Originality/value - First, measuring environmental proactivity using four managerial systems (operative, information, strategic and technical) is innovative and provides a more detailed approach to measuring environmental proactivity. Second, demonstrating a double association between environmental proactivity and performance provides fresh insights into the relationship between these variables

    Automation of product packaging for industrial applications

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    [EN] This work presents a robotic-based solution devised to automate the product packaging in industrial environments. Although the proposed approach is illustrated for the case of the shoe industry, it applies to many other products requiring similar packaging processes. The main advantage obtained with the automated task is that productivity could be significantly increased. The key algorithms for the developed robot system are: object detection using a computer vision system; object grasping; trajectory planning with collision avoidance; and operator interaction using a force/torque sensor. All these algorithms have been experimentally tested in the laboratory to show the effectiveness and applicability of the proposed approach.This work has been partly supported by Ministerio de Economia y Competitividad of the Spanish Government [Grant No. RTC201654086 and PRI-AIBDE-2011-1219], by the Deutscher Akademischer Austauschdienst (DAAD) of the German Government (Projekt-ID 54368155) and by ROBOFOOT project [Grant No. 260159] of the European Commission.Perez-Vidal, C.; Gracia, L.; De Paco, J.; Wirkus, M.; Azorin, J.; De Gea, J. (2018). Automation of product packaging for industrial applications. International Journal of Computer Integrated Manufacturing. 31(2):129-137. https://doi.org/10.1080/0951192X.2017.1369165S12913731

    Real world preventative drug management of migraine among Spanish neurologists

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    BACKGROUND: Many different preventatives have showed efficacy in the treatment of migraine. National guidelines differ in their recommendations and patients' characteristics are usually taken into account in their selection. In Spain, real life use of preventive therapies seems to be heterogeneous. We aimed to evaluate differences in clinical practice and adherence to national guidelines among Spanish neurologists. METHODS: Observational descriptive study. A survey was conducted among neurologists ascribed to the Spanish Society of Neurology. Participants were differentiated in accordance with their dedication to headache disorders. We analysed socio-demographic parameters and evaluated 43 questions considering migraine management as well as therapeutic choices regarding migraine sub-types and finally, neurologists' personal perception. RESULTS: One hundred fifty-five neurologists participated from 17 different regions, 43.4% of them female and 53.3% under 40¿years of age. 34.9% confirmed headache disorders as their main interest. The first choice for preventive therapy in chronic migraine among participants was topiramate (57%) followed by amytriptiline (17.9%) and beta-blockers (14.6%). However in episodic migraine, the preferred options were beta-blockers (47.7%), topiramate (21.5%) and amytriptiline (13.4%). Regarding perceived efficacy, topiramate was considered the best option in chronic migraine (42.7%) followed by onabotulinumtoxinA (25.5%) and amitryptiline (22.4%). Where episodic migraine was concerned, surveyed neurologists perceived topiramate (43.7%) and beta-blockers (30.3%) as the best options. When we evaluated the duration of treatment use with a view to adequate therapeutic response, 43.5% of neurologists preferred 3¿months duration and 39.5% were in favour of 6¿months duration in episodic migraine. However, considering the preferred duration of treatment use in chronic migraine, 20.4% recommended 3¿months, 42.1% preferred 6¿months and 12.5% and 22.4% opted for 9 and 12¿months respectively. When considering onabotulinumtoxinA therapy, the number of prior therapeutic failures was zero in 7.2% of neurologists, one in 5.9%, two in 44.1%, three in 30.9% and four or more in 11.9%. Following an initial treatment failure with onabotulinumtoxinA, 49% of subjects decided against a second treatment. The number of OnabotA procedures before considering it as ineffective was two in 18.9% of neurologists, three in 70.8% and four in 10.4%. CONCLUSIONS: The initial management of migraine among Spanish Neurologists is in line with most guidelines, where first choice preventative drugs are concerned. The Management of episodic migraine differed from chronic migraine, both in terms of neurologist preference and in their perceived efficacy

    Evaluating anemometer drift: A statistical approach to correct biases in wind speed measurement

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    Recent studies on observed wind variability have revealed a decline (termed “stilling”) of near-surface wind speed during the last 30–50 years over many mid-latitude terrestrial regions, particularly in the Northern Hemisphere. The well-known impact of cup anemometer drift (i.e., wear on the bearings) on the observed weakening of wind speed has been mentioned as a potential contributor to the declining trend. However, to date, no research has quantified its contribution to stilling based on measurements, which is most likely due to lack of quantification of the ageing effect. In this study, a 3-year field experiment (2014–2016) with 10-minute paired wind speed measurements from one new and one malfunctioned (i.e., old bearings) SEAC SV5 cup anemometer which has been used by the Spanish Meteorological Agency in automatic weather stations since mid-1980s, was developed for assessing for the first time the role of anemometer drift on wind speed measurement. The results showed a statistical significant impact of anemometer drift on wind speed measurements, with the old anemometer measuring lower wind speeds than the new one. Biases show a marked temporal pattern and clear dependency on wind speed, with both weak and strong winds causing significant biases. This pioneering quantification of biases has allowed us to define two regression models that correct up to 37% of the artificial bias in wind speed due to measurement with an old anemometer

    Real-world preventative drug management of Chronic Migraine among Spanish Neurologists

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    O42 Background: In migraine, the therapeutic preventive drug arsenal is varied. Whenprescribing both Guidelines and patient characteristics are taken intoaccount. In Spain, the use of preventive therapies seems to beheterogeneous.The objective of this study was to evaluate real-life clinical prescribingpractice amongst neurologists in Spain Methods: Observational descriptive study done with a survey by Neurologistsof the Spanish Neurological Society (SEN). Neurologists who participatedwere divided into Headache Specialists or not. The followingdata was collected: socio-demographic data, ; preventive treatmentand choices different migraine sub-types, and their personal perceptionof efficacy and tolerability to different drugs. Results: We analyzed 152 surveys from neurologists around our country.From them: 43.4% were female, 53.3% <40 years, and 34.9% were interestedin headache .In regards to preventive treatment choice; in chronic migraine topiramate(57%) amytriptiline (17.9%) and beta-blockers (14.6%), whereasin episodic migraine the preferred drugs were beta-blockers (47.7%), topiramate (21.5%) and amytriptiline (13.4%).Regarding perceived efficacy, topiramate was considered the bestoption in chronic migraine (42.7%) followed by onabotulinumtoxinA(25.5%) and amitryptiline (22.4%). In episodic migraine, neurologistpreferred topiramate (43.7%) and beta-blockers (30.3%).Regarding the duration of preventive therapy when improvementwas achieved, when treating episodic migraine 43.5% of the surveyedneurologists recommended 3 months and 39.5% preferred 6months. When they treated chronic migraine, 20.4% of neurologistsrecommended 3 months, 42.1% 6 months, 12.5% 9 months and22.4% preferred to maintain treatment during 12 months.When considering onabotulinumtoxinA treatment, the number ofprior therapeutical failures was cero in 7.2% of surveyed, one in5.9%, two in 44.1%, three in 30.9%, and four or more in 11.9%. Theincrease of OnabotulinumtoxinA dose up to 195 UI was consideredby 51% of neurologists after a first ineffective procedure, by 42.2% after two injections, and by 83% after a third infiltration. Surveyedcolleagues admitted to take into account in their decisions mainlypatient comorbidities (70.2%) rather than guidelines (13.9%). Conclusions: Initial management of Migraine among Spanish Neurologists is madewith the preventative drugs which are considered as first choices inmost of the guidelines. Management of episodic migraine differedfrom chronic migraine, both in the order or drugs and the perceptionof the most effective therapy
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