10,881 research outputs found

    Childhood mental health: an ecological analysis of the effects of neighborhood characteristics

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    Research on childhood mental illness traditionally examines risk factors most proximal to the child. However, current trends reflect growing interest in how broader contextual factors contribute to psychopathology risk. In this study, we examined neighborhood‐level indicators as potential sources of chronic strain in a sample of 156 mother–child dyads; children were 8 to 12 years old. For most neighborhood indicators, data were collected at the level of census tracts using publicly available data sets. We hypothesized that these indicators would be both associated with greater overall mental health symptoms and specifically predictive of childhood symptoms of depression. We also examined potential mediators (maternal functioning and family cohesion) and moderators (maternal depression). Neighborhood indicators correlated with parents’ ratings of children's overall mental health problems, but did not correlate with children's self‐report of depression symptoms. Maternal functioning mediated neighborhood effects on children's overall mental health problems. Implications and directions for future research are presented.The current work was supported by the following grants from the National Institutes of Health, National Institute of Mental Health MH066077, MH082861, PI: Martha C. Tompson, Ph.D. and MH082861S1, PI: Gail N. Kemp, M.A., M.P.H. (MH066077 - National Institutes of Health, National Institute of Mental Health; MH082861 - National Institutes of Health, National Institute of Mental Health; MH082861S1 - National Institutes of Health, National Institute of Mental Health)Published versio

    Ratchet-like dynamics of fluxons in annular Josephson junctions driven by bi-harmonic microwave fields

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    Experimental observation of the unidirectional motion of a topological soliton driven by a bi-harmonic ac force of zero mean is reported. The observation is made by measuring the current-voltage characteristics for a fluxon trapped in an annular Josephson junction that was placed into a microwave field. The measured dependence of the fluxon mean velocity (rectified voltage) at zero dc bias versus the phase shift between the first and second harmonic of the driving force is in qualitative agreement with theoretical expectations.Comment: 6 figure

    Focusing of Intense Subpicosecond Laser Pulses in Wedge Targets

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    Two dimensional particle-in-cell simulations characterizing the interaction of ultraintense short pulse lasers in the range 10^{18} \leq I \leq 10^{20} W/cm^{2} with converging target geometries are presented. Seeking to examine intensity amplification in high-power laser systems, where focal spots are typically non-diffraction limited, we describe key dynamical features as the injected laser intensity and convergence angle of the target are systematically varied. We find that laser pulses are focused down to a wavelength with the peak intensity amplified by an order of magnitude beyond its vacuum value, and develop a simple model for how the peak location moves back towards the injection plane over time. This performance is sustained over hundreds of femtoseconds and scales to laser intensities beyond 10^{20} W/cm^{2} at 1 \mu m wavelength.Comment: 5 pages, 6 figures, accepted for publication in Physics of Plasma

    The spectrum of small-scale density fluctuations in the solar wind

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    Interplanetary scintillation observations at frequencies between 74 and 1400 MHz and solar elongations in the range 10–90° are combined to determine the form of the wavenumber spectrum of electron density fluctuations in the range 10⁻³ < k < 10⁻Âč/km (where k = 2π/λ). The data are best explained by a spectrum in which there is a genuine scale-length; they are not consistent with a simple power-law spectrum. This suggests that turbulence may be less important than some kind of plasma instability in generating small-scale density fluctuations. The relevance of these conclusions to the use of IPS for determining radio source structure is discussed

    User evaluation of an interactive learning framework for single-arm and dual-arm robots

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    The final publication is available at link.springer.comSocial robots are expected to adapt to their users and, like their human counterparts, learn from the interaction. In our previous work, we proposed an interactive learning framework that enables a user to intervene and modify a segment of the robot arm trajectory. The framework uses gesture teleoperation and reinforcement learning to learn new motions. In the current work, we compared the user experience with the proposed framework implemented on the single-arm and dual-arm Barrett’s 7-DOF WAM robots equipped with a Microsoft Kinect camera for user tracking and gesture recognition. User performance and workload were measured in a series of trials with two groups of 6 participants using two robot settings in different order for counterbalancing. The experimental results showed that, for the same task, users required less time and produced shorter robot trajectories with the single-arm robot than with the dual-arm robot. The results also showed that the users who performed the task with the single-arm robot first experienced considerably less workload in performing the task with the dual-arm robot while achieving a higher task success rate in a shorter time.Peer ReviewedPostprint (author's final draft

    How much dark matter is there inside early-type galaxies?

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    We study the luminous mass as a function of the dynamical mass inside the effective radius (r_e) of early-type galaxies (ETGs) to search for differences between these masses. We assume Newtonian dynamics and that any difference between these masses is due to the presence of dark matter. We use several samples of ETGs -ranging from 19 000 to 98 000 objects- from the ninth data release of the Sloan Digital Sky Survey. We perform Monte Carlo (MC) simulations of galaxy samples and compare them with real samples. The main results are: i) MC simulations show that the distribution of the dynamical vs. luminous mass depends on the mass range where the ETGs are distributed (geometric effect). This dependence is caused by selection effects and intrinsic properties of the ETGs. ii) The amount of dark matter inside r_e is approximately 7% +- 22%. iii) This amount of dark matter is lower than the minimum estimate (10%) found in the literature and four times lower than the average (30%) of literature estimates. However, if we consider the associated error, our estimate is of the order of the literature average.Comment: 24 pages, 12 figures. MNRAS accepte

    Force/Torque Sensing for Soft Grippers using an External Camera

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    Robotic manipulation can benefit from wrist-mounted force/torque (F/T) sensors, but conventional F/T sensors can be expensive, difficult to install, and damaged by high loads. We present Visual Force/Torque Sensing (VFTS), a method that visually estimates the 6-axis F/T measurement that would be reported by a conventional F/T sensor. In contrast to approaches that sense loads using internal cameras placed behind soft exterior surfaces, our approach uses an external camera with a fisheye lens that observes a soft gripper. VFTS includes a deep learning model that takes a single RGB image as input and outputs a 6-axis F/T estimate. We trained the model with sensor data collected while teleoperating a robot (Stretch RE1 from Hello Robot Inc.) to perform manipulation tasks. VFTS outperformed F/T estimates based on motor currents, generalized to a novel home environment, and supported three autonomous tasks relevant to healthcare: grasping a blanket, pulling a blanket over a manikin, and cleaning a manikin's limbs. VFTS also performed well with a manually operated pneumatic gripper. Overall, our results suggest that an external camera observing a soft gripper can perform useful visual force/torque sensing for a variety of manipulation tasks.Comment: Accepted for presentation at 2023 IEEE International Conference on Robotics and Automation (ICRA

    Physics Analysis Expert PAX: First Applications

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    PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to assist teams in particle physics data analysis issues. The core of PAX are event interpretation containers, holding relevant information about and possible interpretations of a physics event. Providing this new level of abstraction beyond the results of the detector reconstruction programs, PAX facilitates the buildup and use of modern analysis factories. Class structure and user command syntax of PAX are set up to support expert teams as well as newcomers in preparing for the challenges expected to arise in the data analysis at future hadron colliders.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 10 eps figures. PSN THLT00
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