4,673 research outputs found

    Does tiny-scale atomic structure exist in the interstellar medium ?

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    We report on preliminary results from the recent multi-epoch neutral hydrogen absorption measurements toward three pulsars, B0823+26, B1133+16 and B2016+28, using the Arecibo telescope. We do not find significant variations in optical depth profiles over periods of 0.3 and 9--10 yr, or on spatial scales of 10--20 and 70--85 AU. The large number of non detections of the tiny scale atomic structure suggests that the AU-sized structure is not ubiquitous in the interstellar medium and could be quite a rare phenomenon.Comment: Accepted by ApJ Letters, 5 pages, 2 figure

    Instant Two-Body Equation in Breit Frame

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    A quasipotential formalism for elastic scattering from relativistic bound states is based on applying an instant constraint to both initial and final states in the Breit frame. This formalism is advantageous for the analysis of electromagnetic interactions because current conservation and four momentum conservation are realized within a three-dimensional formalism. Wave functions are required in a frame where the total momentum is nonzero, which means that the usual partial wave analysis is inapplicable. In this work, the three-dimensional equation is solved numerically, taking into account the relevant symmetries. A dynamical boost of the interaction also is needed for the instant formalism, which in general requires that the boosted interaction be defined as the solution of a four-dimensional equation. For the case of a scalar separable interaction, this equation is solved and the Lorentz invariance of the three-dimensional formulation using the boosted interaction is verified. For more realistic interactions, a simple approximation is used to characterize the boost of the interaction.Comment: 20 pages in revtex 3, 3 figures. Fixed reform/tex errors

    Magnescope: Applications in nondestructive evaluation

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    This paper describes recent results obtained with the Magnescope, which has been used on location in industrial environments and has successfully detected impending fatigue failure, creep damage, applied stress, and microstructural differences. It is concluded that the device provides a useful nondestructive method for evaluating the mechanical properties of materials through the measurement of their structure sensitive magnetic properties

    MRI and Neuropsychological Correlates of Carbon Monoxide Exposure: A Case Report

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    A 45-year-old woman experienced long-term, chronic exposure to carbon monoxide in the restaurant kitchen where she was employed as a cook. After returning to the restaurant after 5 days off work, she noticed that her symptoms returned immediately; she then aired out the room and called the gas company. Approximately 6 hr after a leak was detected, the patient went to the hospital, where her carboxyhemoglobin was found to be within normal limits and results of a neurologic examination were described as normal. Based on her symptoms, the patient believed she had been exposed to CO for at least 1 year before the leak was discovered. Initially, she experienced flu-like symptoms, which eventually resolved. At the time of her first neuropsychological evaluation (17 months after the exposure was identified), her persisting complaints included difficulties in reading, writing, speaking and word retrieval. The test results were consistent with secondary frontal lobe dysfunction associated with subcortical disorders such as those seen after CO exposure. Results of a subsequent neuropsychological examination (29 months postexposure) showed slight improvement in performance, but her performance was still consistent with mild frontal/subcortical dysfunction. Although the initial screening of a brain magnetic resonance image (MRI) performed 15 months after the exposure was interpreted as being within normal limits, two subsequent blind reviews of the same scans identified multiple bilateral lesions in the basal ganglia, which were consistent with chronic CO exposure. We present this case as an example of the utility of MRI and neuropsychological examinations in detecting central nervous system dysfunction secondary to CO exposure

    Classifying foods in contexts: How adults categorize foods for different eating settings

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    This project examined adults\u27 food cognitions by applying schema theory to explain how adults categorized foods for different contexts. Qualitative interviews and repeated card sort activities for different eating contexts were conducted to elicit as many food categories as possible form 42 US adults. Participants labeled card sort piles with their own words, providing 991 card sort labels. Qualitative analysis of the labels resulted in the emergence of 12 category types. Personal-experience-based types were specific to the individual (e.g., Preference). Context-based types were related to situational aspects of eating episodes (e.g., Location). Food-based types were related to intrinsic properties of the foods (e.g., Physical characteristics). Different combinations of the 12 category types were used for different eating contexts. Personal-experience and context-based types were used most frequently overall. Some category types were used more frequently for specific contexts (e.g., Convenience for work contexts). Food-based taxonomic category types were used most frequently when no context was defined. Script-oriented categories were more often used in response to specific eating contexts. These findings provide a framework to consider how individuals classify foods in real-life eating contexts. Attention to personal-experience and context-based category types may help improve understanding of relationships between knowledge and food choice behaviors
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