1,039 research outputs found

    Generalized hydrodynamics of a dilute finite-sized particles suspension: Dynamic viscosity

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    We present a mesoscopic hydrodynamic description of the dynamics of colloidal suspensions. We consider the system as a gas of Brownian particles suspended in a Newtonian heat bath subjected to stationary non-equilibrium conditions imposed by a velocity field. Using results already obtained in previous studies in the field by means of a generalized Fokker-Planck equation, we obtain a set of coupled differential equations for the local diffusion current and the evolution of the total stress tensor. We find that the dynamic shear viscosity of the system contains contributions arising from the finite size of the particles.Comment: To appear in Physical Review

    Evaluating brain parcellations using the distance-controlled boundary coefficient

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    One important approach to human brain mapping is to define a set of distinct regions that can be linked to unique functions. Numerous brain parcellations have been proposed, using cytoarchitectonic, structural, or functional magnetic resonance imaging (fMRI) data. The intrinsic smoothness of brain data, however, poses a problem for current methods seeking to compare different parcellations. For example, criteria that simply compare within-parcel to between-parcel similarity provide even random parcellations with a high value. Furthermore, the evaluation is biased by the spatial scale of the parcellation. To address this problem, we propose the distance-controlled boundary coefficient (DCBC), an unbiased criterion to evaluate discrete parcellations. We employ this new criterion to evaluate existing parcellations of the human neocortex in their power to predict functional boundaries for an fMRI data set with many different tasks, as well as for resting-state data. We find that common anatomical parcellations do not perform better than chance, suggesting that task-based functional boundaries do not align well with sulcal landmarks. Parcellations based on resting-state fMRI data perform well; in some cases, as well as a parcellation defined on the evaluation data itself. Finally, multi-modal parcellations that combine functional and anatomical criteria perform substantially worse than those based on functional data alone, indicating that functionally homogeneous regions often span major anatomical landmarks. Overall, the DCBC advances the field of functional brain mapping by providing an unbiased metric that compares the predictive ability of different brain parcellations to define brain regions that are functionally maximally distinct

    The role of feedback in the production of skilled finger sequences

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    Actions involving fine control of the hand, for example, grasping an object, rely heavily on sensory information from the fingertips. Although the integration of feedback during the execution of individual movements is well understood, less is known about the use of sensory feedback in the control of skilled movement sequences. To address this gap, we trained participants to produce sequences of finger movements on a keyboard-like device over a 4-day training period. Participants received haptic, visual, and auditory feedback indicating the occurrence of each finger press. We then either transiently delayed or advanced the feedback for a single press by a small amount of time (30 or 60 ms). We observed that participants rapidly adjusted their ongoing finger press by either accelerating or prolonging the ongoing press, in accordance with the direction of the perturbation. Furthermore, we could show that this rapid behavioral modulation was driven by haptic feedback. Although these feedback-driven adjustments reduced in size with practice, they were still clearly present at the end of training. In contrast to the directionally specific effect we observed on the perturbed press, a feedback perturbation resulted in a delayed onset of the subsequent presses irrespective of perturbation direction or feedback modality. This observation is consistent with a hierarchical organization of even very skilled and fast movement sequences, with different levels reacting distinctly to sensory perturbations. NEW & NOTEWORTHY Sensory feedback is important during the execution of a movement. However, little is known about how sensory feedback is used during the production of movement sequences. Here, we show two distinct feedback processes in the execution of fast finger movement sequences. By transiently delaying or advancing the feedback of a single press within a sequence, we observed a directionally specific effect on the perturbed press and a directionally non-specific effect on the subsequent presses

    Systematic Approaches for Telemedicine and Data Coordination for COVID-19 in Baja California, Mexico

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    Conference proceedings info: ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologies Raleigh, HI, United States, March 24-26, 2023 Pages 529-542We provide a model for systematic implementation of telemedicine within a large evaluation center for COVID-19 in the area of Baja California, Mexico. Our model is based on human-centric design factors and cross disciplinary collaborations for scalable data-driven enablement of smartphone, cellular, and video Teleconsul-tation technologies to link hospitals, clinics, and emergency medical services for point-of-care assessments of COVID testing, and for subsequent treatment and quar-antine decisions. A multidisciplinary team was rapidly created, in cooperation with different institutions, including: the Autonomous University of Baja California, the Ministry of Health, the Command, Communication and Computer Control Center of the Ministry of the State of Baja California (C4), Colleges of Medicine, and the College of Psychologists. Our objective is to provide information to the public and to evaluate COVID-19 in real time and to track, regional, municipal, and state-wide data in real time that informs supply chains and resource allocation with the anticipation of a surge in COVID-19 cases. RESUMEN Proporcionamos un modelo para la implementación sistemática de la telemedicina dentro de un gran centro de evaluación de COVID-19 en el área de Baja California, México. Nuestro modelo se basa en factores de diseño centrados en el ser humano y colaboraciones interdisciplinarias para la habilitación escalable basada en datos de tecnologías de teleconsulta de teléfonos inteligentes, celulares y video para vincular hospitales, clínicas y servicios médicos de emergencia para evaluaciones de COVID en el punto de atención. pruebas, y para el tratamiento posterior y decisiones de cuarentena. Rápidamente se creó un equipo multidisciplinario, en cooperación con diferentes instituciones, entre ellas: la Universidad Autónoma de Baja California, la Secretaría de Salud, el Centro de Comando, Comunicaciones y Control Informático. de la Secretaría del Estado de Baja California (C4), Facultades de Medicina y Colegio de Psicólogos. Nuestro objetivo es proporcionar información al público y evaluar COVID-19 en tiempo real y rastrear datos regionales, municipales y estatales en tiempo real que informan las cadenas de suministro y la asignación de recursos con la anticipación de un aumento de COVID-19. 19 casos.ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologieshttps://doi.org/10.1007/978-981-99-3236-

    Level of Precompetitive Anxiety and Self-Confidence in High Level Padel Players

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    The objectives of the present study were firstly to evaluate precompetitive anxiety and self-confidence (SC) in padel players according to their playing level; and secondly, to study the factors that influence the levels of precompetitive anxiety and SC. One hundred padel players, all of whom were federated men (age: M = 27.6, SD = 7.5 years; weight: M = 73.4, SD = 9.8 kg; height: M = 175.6, SD = 7.5 cm) participated in the research. The CSAI-2 (Competitive State Anxiety Inventory-2) questionnaire was used and a one-way ANOVA and a two- and three-ways MANOVA were conducted. The results show that the players from a better category had higher scores in SC and lower scores in somatic anxiety (SA) (eta(2) = 0.10 and eta(2) = 0.12, respectively). Moreover, the factors of category, body mass index (BMI) and experience, predicted 82% of the variance explained by the SC of the player. As a conclusion, this study has made it possible to ascertain that the playing category, understood as the level of the padel players, determines the levels of anxiety and SC and represents a key factor for the prediction of sports performance

    Estimating Vaccine Efficacy in Stochastic SIR Epidemic Models with Non Homogeneous Mixing

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    This issue was undated. The date given is an estimate.34 pages, 1 article*Estimating Vaccine Efficacy in Stochastic SIR Epidemic Models with Non Homogeneous Mixing* (Hernandez-Suarez, Carlos M.; Castillo-Chavez, Carlos) 34 page

    Critical Response Models for Foot-and-Mouth Disease Epidemics

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    28 pages, 1 article*Critical Response Models for Foot-and-Mouth Disease Epidemics* (Oritz, Johnsie; Rivera, Manuel A.; Rubin, Daniel; Ruiz, Israel; Hernandez, Carlos M.; Castillo-Chavez, Carlos) 28 page

    No evidence for motor-recovery-related cortical connectivity changes after stroke using resting-state fMRI

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    It has been proposed that a form of cortical reorganization (changes in functional connectivity between brain areas) can be assessed with resting-state (rs) functional MRI (fMRI). Here, we report a longitudinal data set collected from 19 patients with subcortical stroke and 11 controls. Patients were imaged up to five times over 1 year. We found no evidence, using rs-fMRI, for longitudinal poststroke cortical connectivity changes despite substantial behavioral recovery. These results could be construed as questioning the value of resting-state imaging. Here, we argue instead that they are consistent with other emerging reasons to challenge the idea of motor-recovery-related cortical reorganization poststroke when conceived of as changes in connectivity between cortical areas. NEW & NOTEWORTHY We investigated longitudinal changes in functional connectivity after stroke. Despite substantial motor recovery, we found no differences in functional connectivity patterns between patients and controls, nor any changes over time. Assuming that rs-fMRI is an adequate method to capture connectivity changes between cortical regions after brain injury, these results provide reason to doubt that changes in cortico-cortical connectivity are the relevant mechanism for promoting motor recovery

    Caracteristicas reproductivas de ovejas Pelibuey sincronizadas e inducidas a la pubertad

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    El objetivo del experimento fue analizar las características reproductivas de ovejas Pelibuey sincronizadas (T1: n = 7) e inducidas a la pubertad (T2: n = 7). Las ovejas del T1 se presincronizaron, siete días después se aplicó a todas las ovejas FGA intravaginal durante 12 d y dos días antes de retirar el FGA se aplicó eCG. La incidencia de estro fue de 100 % en T1 y T2. El inicio del estro no fue diferente (P>0.05) con valores 21.4 ± 2.2 h y 24.2 ± 3.2 h para T1 y T2. La duración del estro fue de 60.5 ± 6.6 y 41.3 ± 3.6 para T1 y T2 (P<0.05). El inicio, duración y amplitud del pulso preovulatorio de LH no mostró diferencias con valores de 24.5 ± 1.7 y 24.2 ± 4.7 h, 13.4 ± 1.2 y 14.0 ± 0.6 h, 18.1 ± 2.7 y 21.3 ± 3.1 ng mL-1 para T1 y T2 respectivamente. La tasa de gestación no fue diferente con 100 y 85.71 % para T1 y T2. La tasa ovulatoria y prolificidad fue diferente (P<0.05) con valores de 4.4 ± 1.2 y 2.7 ± 0.4 y 2.5 ± 0.2 y 1.4 ± 0.4, para el T1 y T2 respectivamente. Se concluyó que el uso de FGA y eCG en ovejas Pelibuey es recomendable para inducir la pubertad, ya que las características reproductivas analizadas son aceptables, su implementación puede ser factible en programas de inseminación a tiempo fijo
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