3,268 research outputs found
Realisations of Symmetry
We perform a systematic investigation of free-scalar realisations of the
Za\-mo\-lod\-chi\-kov algebra in which the operator product of two
spin-three generators contains a non-zero operator of spin four which has
vanishing norm. This generalises earlier work where such an operator was
required to be absent. By allowing this spin-four null operator we obtain
several realisations of the algebra both in terms of two scalars as well
as in terms of an arbitrary number of free scalars. Our analysis is
complete for the case of two-scalar realisations.Comment: 14 pages, LATEX, UG-6/9
Semi-isostatic densification of heat-treated radiata pine
Semi-isostatic densification is a useful method to increase the density and to improve the mechanical properties of fast-grown softwood species like radiata pine. A major disadvantage of this method is the almost complete recovery of the original dimensions when densified wood is exposed to moisture. Heat treatment improves the dimensional stability of wood and might be a useful method to prevent this shape-recovery after densification. However, no or only a limited effect on the shape-recovery was found when densified radiata pine was exposed to moisture
Employment status, job characteristics and work-related health experience of people with a lower limb amputation in the Netherlands
Objectives: To describe the occupational situation of people with lower limb amputations in The Netherlands and to compare the health experience of workings and nonworking amputee patients with a nonimpaired reference population. Design: Cross-sectional study in which patients completed a questionnaire about their job participation. type of job, workplace adjustments to their limb loss, their position in the company, and a general health questionnaire. Setting: Orthopsdic workshops in The Netherlands with a population of lower limb amputees. Patients: Subjects were recruited from orthopedic workshops in the Netherlands. They ranged in age from Is to 60 years (mean, 44.5yr) and had a lower limb amputated at least 2 years (mean, 19.6yr) before this study. Main Outcome measures: A self-report questionnaire, with 1 part concerning patient characteristics and amputation-related factors, and the other concerning job characteristics, vocational handicaps, work adjustments, and working conditions; and a general health questionnaire (RAND-36) to measure health status. Results: Responses were received from 652 of the 687 patients (response: rate, 95%) who were sent the questionnaire. Sixty-foul percent of the respondents were working at the rime of the study (comparable with the employment rate of the general Dutch population), 31 % had work experience but were not presently working, and 5% had no work experience. After their amputations, people shifted to less physically demanding work. The mean delay between the amputation and the return to work was 2.3 years. Many people wished their work was better adjusted to the limitations presented by their disability and they mentioned having problems concerning possibilities fur promotion. Seventy-eight percent of those who stopped working within 2 years after the amputation said that amputation-related factors played a role in their decision. Thirty-four percent said that they might have worked longer if certain adjustments had been made. The health experience of people who were no longer working was significantly worse than that of the working people with amputations. Conclusions: Although amputee patients had a relatively good rate of job participation, they reported problems concerning the long delay between amputation and return to work, problems in finding suitable jobs, fewer possibilities for promotion, and problems in obtaining needed workplace modifications. People who had to stop working because of the amputation showed a worse health experience than working people
More on general -brane solutions
Recently it was found that the complete integration of the
Einstein-dilaton-antisymmetric form equations depending on one variable and
describing static singly charged -branes leads to two and only two classes
of solutions: the standard asymptotically flat black -brane and the
asymptotically non-flat -brane approaching the linear dilaton background at
spatial infinity. Here we analyze this issue in more details and generalize the
corresponding uniqueness argument to the case of partially delocalized branes.
We also consider the special case of codimension one and find, in addition to
the standard domain wall, the black wall solution. Explicit relations between
our solutions and some recently found -brane solutions ``with extra
parameters'' are presented.Comment: 29 pages, 2 figure
Mirror effect induced by the dilaton field on the Hawking radiation
We discuss the string creation in the near-extremal NS1 black string
solution. The string creation is described by an effective field equation
derived from a fundamental string action coupled to the dilaton field in a
conformally invariant manner. In the non-critical string model the dilaton
field causes a timelike mirror surface outside the horizon when the size of the
black string is comparable to the Planck scale. Since the fundamental strings
are reflected by the mirror surface, the negative energy flux does not
propagate across the surface. This means that the evaporation stops just before
the naked singularity of the extremal black string appears even though the
surface gravity is non-zero in the extremal limit.Comment: 15 page
Executive functioning in adult ADHD: a meta-analytic review
. CONCLUSIONS: Neuropsychological difficulties in adult ADHD may not be confined to executive functioning. The field is in urgent need of better-designed executive functioning tests, methodological improvements, and direct comparisons with multiple clinical groups to answer questions of specificit
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