759 research outputs found

    Low-energy fusion caused by an interference

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    Fusion of two deuterons of room temperature energy is studied. The nuclei are in vacuum with no connection to any external source (electric or magnetic field, illumination, surrounding matter, traps, etc.) which may accelerate them. The energy of the two nuclei is conserved and remains small during the motion through the Coulomb barrier. The penetration through this barrier, which is the main obstacle for low-energy fusion, strongly depends on a form of the incident flux on the Coulomb center at large distances from it. In contrast to the usual scattering, the incident wave is not a single plane wave but the certain superposition of plane waves of the same energy and various directions, for example, a convergent conical wave. As a result of interference, the wave function close to the Coulomb center is determined by a cusp caustic which is probed by de Broglie waves. The particle flux gets away from the cusp and moves to the Coulomb center providing a not small probability of fusion (cusp driven tunneling). Getting away from a caustic cusp also occurs in optics and acoustics

    Institutionalizing Faculty Mentoring within a Community of Practice Model

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    In higher education, faculty work is typically enacted—and rewarded—on an individual basis. Efforts to promote collaboration run counter to the individual and competitive reward systems that characterize higher education. Mentoring initiatives that promote faculty collaboration and support also defy the structural and cultural norms of higher education. Collaborative mentoring initiatives, however, support all faculty to be lifelong learners. We analyze a reciprocal model of mentoring—a community of practice for mentoring—that integrates collaborative mentoring into faculty’s daily work. Additionally, we examine the dilemmas, benefits, and costs of institutionalizing a community of practice model for mentoring in higher education. Our analyses indicate that communities of practice can be fruitful sites of mentoring for all faculty when members mutually engage in shared practices required by the institution. Additionally, such communities nurture relationships and emotional support that sustain engagement in practice and reduce isolation. Given these benefits, we argue that communities of practice should be publically recognized at the institutional level as viable mechanisms for faculty mentoring and learning. Institutions of higher education must explicitly support a campus culture of collaboration and lifelong learning. Findings offer guidance for faculty and center for teaching and learning (CTL) interested in starting or participating in communities of practice

    A new look at low-energy nuclear reaction (LENR) research: a response to Shanahan

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    In his criticisms of the review article on LENR by Krivit and Marwan, Shanahan has raised a number of issues in the areas of calorimetry, heat after death, elemental transmutation, energetic particle detection using CR-39, and the temporal correlation between heat and helium-4. These issues are addressed by the researchers who conducted the original work that was discussed in the Krivit-Marwan (K&M) review paper

    Similarity of fMRI activity patterns in left perirhinal cortex reflects semantic similarity between words

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    How verbal and nonverbal visuoperceptual input connects to semantic knowledge is a core question in visual and cognitive neuroscience, with significant clinical ramifications. In an event-related functional magnetic resonance imaging (fMRI) experiment we determined how cosine similarity between fMRI response patterns to concrete words and pictures reflects semantic clustering and semantic distances between the represented entities within a single category. Semantic clustering and semantic distances between 24 animate entities were derived from a concept-feature matrix based on feature generation by >1000 subjects. In the main fMRI study, 19 human subjects performed a property verification task with written words and pictures and a low-level control task. The univariate contrast between the semantic and the control task yielded extensive bilateral occipitotemporal activation from posterior cingulate to anteromedial temporal cortex. Entities belonging to a same semantic cluster elicited more similar fMRI activity patterns in left occipitotemporal cortex. When words and pictures were analyzed separately, the effect reached significance only for words. The semantic similarity effect for words was localized to left perirhinal cortex. According to a representational similarity analysis of left perirhinal responses, semantic distances between entities correlated inversely with cosine similarities between fMRI response patterns to written words. An independent replication study in 16 novel subjects confirmed these novel findings. Semantic similarity is reflected by similarity of functional topography at a fine-grained level in left perirhinal cortex. The word specificity excludes perceptually driven confounds as an explanation and is likely to be task dependent.Rose Bruffaerts, Patrick Dupont, Ronald Peeters, Simon De Deyne, Gerrit Storms and Rik Vandenbergh

    DOE Project on Heavy Vehicle Aerodynamic Drag

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    Class 8 tractor-trailers consume 11-12% of the total US petroleum use. At highway speeds, 65% of the energy expenditure for a Class 8 truck is in overcoming aerodynamic drag. The project objective is to improve fuel economy of Class 8 tractor-trailers by providing guidance on methods of reducing drag by at least 25%. A 25% reduction in drag would present a 12% improvement in fuel economy at highway speeds, equivalent to about 130 midsize tanker ships per year. Specific goals include: (1) Provide guidance to industry in the reduction of aerodynamic drag of heavy truck vehicles; (2) Develop innovative drag reducing concepts that are operationally and economically sound; and (3) Establish a database of experimental, computational, and conceptual design information, and demonstrate the potential of new drag-reduction devices. The studies described herein provide a demonstration of the applicability of the experience developed in the analysis of the standard configuration of the Generic Conventional Model. The modeling practices and procedures developed in prior efforts have been applied directly to the assessment of new configurations including a variety of geometric modifications and add-on devices. Application to the low-drag 'GTS' configuration of the GCM has confirmed that the error in predicted drag coefficients increases as the relative contribution of the base drag resulting from the vehicle wake to the total drag increases and it is recommended that more advanced turbulence modeling strategies be applied under those circumstances. Application to a commercially-developed boat tail device has confirmed that this restriction does not apply to geometries where the relative contribution of the base drag to the total drag is reduced by modifying the geometry in that region. Application to a modified GCM geometry with an open grille and radiator has confirmed that the underbody flow, while important for underhood cooling, has little impact on the drag coefficient of the vehicle. Furthermore, the evaluation of the impact of small changes in radiator or grille dimensions has revealed that the total drag is not particularly sensitive to those changes. This observation leads to two significant conclusions. First, a small increase in radiator size to accommodate heat rejection needs related to new emissions restrictions may be tolerated without significant increases in drag losses. Second, efforts to reduce drag on the tractor requires that the design of the entire tractor be treated in an integrated fashion. Simply reducing the size of the grille will not provide the desired result, but the additional contouring of the vehicle as a whole which may be enabled by the smaller radiator could have a more significant effect

    Re-Identification for Improved People Tracking

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    Re-identification is usually defined as the problem of deciding whether a person currently in the field of view of a camera has been seen earlier either by that camera or another. However, a different version of the problem arises even when people are seen by multiple cameras with overlapping fields of view. Current tracking algorithms can easily get confused when people come close to each other and merge trajectory fragments into trajectories that include erroneous identity switches. Preventing this means re-identifying people across trajectory fragments. In this chapter, we show that this can be done very effectively by formulating the problem as a minimum-cost maximum-flow linear program. This version of the re-identification problem can be solved in real-time and produces trajectories without identity switches. We demonstrate the power of our approach both in single- and multi-camera setups to track pedestrians, soccer players, and basketball players

    Feature integration in natural language concepts

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    Two experiments measured the joint influence of three key sets of semantic features on the frequency with which artifacts (Experiment 1) or plants and creatures (Experiment 2) were categorized in familiar categories. For artifacts, current function outweighed both originally intended function and current appearance. For biological kinds, appearance and behavior, an inner biological function, and appearance and behavior of offspring all had similarly strong effects on categorization. The data were analyzed to determine whether an independent cue model or an interactive model best accounted for how the effects of the three feature sets combined. Feature integration was found to be additive for artifacts but interactive for biological kinds. In keeping with this, membership in contrasting artifact categories tended to be superadditive, indicating overlapping categories, whereas for biological kinds, it was subadditive, indicating conceptual gaps between categories. It is argued that the results underline a key domain difference between artifact and biological concepts

    Tracking Interacting Objects Optimally Using Integer Programming

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    In this paper, we show that tracking different kinds of interacting objects can be formulated as a network-flow Mixed Integer Program. This is made possible by tracking all objects simultaneously and expressing the fact that one object can appear or disappear at locations where another is in terms of linear flow constraints. We demonstrate the power of our approach on scenes involving cars and pedestrians, bags being carried and dropped by people, and balls being passed from one player to the next in a basketball game. In particular, we show that by estimating jointly and globally the trajectories of different types of objects, the presence of the ones which were not initially detected based solely on image evidence can be inferred from the detections of the others
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