6,972 research outputs found
Advances in Moire interferometry for thermal response of composites
An experimental technique for the precise measurement of the thermal response of both sides of a laminated composite coupon specimen uses Moire interferometry with fringe multiplication which yields a sensitivity of 833 nm (32.8 micro in.) per fringe. The reference gratings used are virtual gratings and are formed by partially mirrorized glass prisms in close proximity to the specimen. Results are compared with both results obtained from tests which used Moire interferometry on one side of composite laminates, and with those predicted by classical lamination theory. The technique is shown to be capable of producing the sensitivity and accuracy necessary to measure a wide range of thermal responses and to detect small side to side variations in the measured response. Tests were conducted on four laminate configurations of T300/5208 graphite epoxy over a temperature range of 297 K (75 F) to 422 K (300 F). The technique presented allows for the generation of reference gratings for temperature regimes well outside that used in these tests
Maxwell's theory on a post-Riemannian spacetime and the equivalence principle
The form of Maxwell's theory is well known in the framework of general
relativity, a fact that is related to the applicability of the principle of
equivalence to electromagnetic phenomena. We pose the question whether this
form changes if torsion and/or nonmetricity fields are allowed for in
spacetime. Starting from the conservation laws of electric charge and magnetic
flux, we recognize that the Maxwell equations themselves remain the same, but
the constitutive law must depend on the metric and, additionally, may depend on
quantities related to torsion and/or nonmetricity. We illustrate our results by
putting an electric charge on top of a spherically symmetric exact solution of
the metric-affine gauge theory of gravity (comprising torsion and
nonmetricity). All this is compared to the recent results of Vandyck.Comment: 9 pages, REVTeX, no figures; minor changes, version to be published
in Class. Quantum Gra
Measures of self-regulation used in adult rehabilitation populations:A systematic review and content screening
Objective We aimed to identify generic measures of self-regulation and to examine the degree to which these measures fit a recently developed conceptual model of self-regulation in a rehabilitation context. Data sources Pubmed, Embase, PsycInfo, and CINAHL were searched. Review methods Articles were included if they were published between January 2015 and August 2020 and reported on empirical studies (trials and observational studies) using a measure of self-regulation or a related concept, in an adult rehabilitation population. Main content was analysed by linking all items of the selected measures to one or more of the six sub-themes of self-regulation: (1) insight into physical and cognitive impairments, (2) insight into the consequences of the impairments, (3) insight into abilities, (4) to be able to communicate limitations, (5) trust in body and functioning, and (6) make use of abilities. Results Two reviewers independently screened 7808 abstracts, resulting in the inclusion of 236 articles. In these articles, 80 different measures were used to assess self-regulation or related concept. Nineteen of these measures met the inclusion criteria and were included for the content analyses. Nine of these were self-efficacy measures. No measures covered four or more of the six sub-themes of self-regulation. The three sub-themes on gaining insights were covered less compared to the sub-domains 'trust' and 'make use of abilities'. Conclusions Many measures on self-regulation exist None of these measures cover all six sub-themes of self-regulation considered important to measure self-regulation as a rehabilitation outcome
Corrections to Sirlin's Theorem in Chiral Perturbation Theory
We present the results of the first two-loop calculation of a form factor in
full Chiral Perturbation Theory. We choose a specific
linear combination of and form factors (the one
appearing in Sirlin's theorem) which does not get contributions from order
operators with unknown constants. For the charge radii, the correction to
the previous one-loop result turns out to be significant, but still there is no
agreement with the present data due to large experimental uncertainties in the
kaon charge radii.Comment: 6 pages, Latex, 2 LaTeX figure
Spinal cord injuries and bowel stomas:timing and satisfaction with stoma formation and alterations in quality of life
STUDY DESIGN: Cross-sectional study.OBJECTIVES: Neurogenic bowel dysfunction (NBD) is frequent among individuals with spinal cord injury (SCI) and is often difficult to treat. A bowel stoma is considered the last-resort treatment option for individuals with SCI and severe NBD. This study aims to explore whether individuals are satisfied with their bowel stoma and how they feel about the timing of stoma formation. Furthermore, we want to explore side effects addressing diversion colitis and changes in quality of life (QOL) after stoma formation.SETTING: Netherlands, community.METHODS: We included participants aged at least 18 years with a traumatic or non-traumatic SCI and bowel stoma. Questions regarding timing of stoma formation, alterations in QOL after stoma formation and experienced side effects of the bowel stoma were addressed in an online questionnaire.RESULTS: In total 23 participants filled out the online survey. Twenty-two participants (96%) were satisfied with their bowel stoma and 83% felt their stoma was placed too late or far too late. The large majority (>80%) reported improvements in the four QOL domains after the procedure. Nine participants reported stoma-related problems in the last month. In the last three months, seven participants (30%) reported to have diversion colitis. Four of these seven participants experienced this at least once a week or more. Two participants stated this had moderate influence on daily activities.CONCLUSIONS: Most participants with SCI experienced improvement in QOL and in retrospect wanted their bowel stoma earlier. Early, extensive conversations to inform individuals about bowel stoma as a treatment option is recommended.</p
Semirelativistic stability of N-boson systems bound by 1/r pair potentials
We analyze a system of self-gravitating identical bosons by means of a
semirelativistic Hamiltonian comprising the relativistic kinetic energies of
the involved particles and added (instantaneous) Newtonian gravitational pair
potentials. With the help of an improved lower bound to the bottom of the
spectrum of this Hamiltonian, we are able to enlarge the known region for
relativistic stability for such boson systems against gravitational collapse
and to sharpen the predictions for their maximum stable mass.Comment: 11 pages, considerably enlarged introduction and motivation,
remainder of the paper unchange
Decomposition by ectomycorrhizal fungi alters soil carbon storage in a simulation model
Carbon cycle models often lack explicit belowground organism activity, yet belowground organisms regulate carbon storage and release in soil. Ectomycorrhizal fungi are important players in the carbon cycle because they are a conduit into soil for carbon assimilated by the plant. It is hypothesized that ectomycorrhizal fungi can also be active decomposers when plant carbon allocation to fungi is low. Here, we reviewed the literature on ectomycorrhizal decomposition and we developed a simulation model of the plant-mycorrhizae interaction where a reduction in plant productivity stimulates ectomycorrhizal fungi to decompose soil organic matter. Our review highlights evidence demonstrating the potential for ectomycorrhizal fungi to decompose soil organic matter. Our model output suggests that ectomycorrhizal activity accounts for a portion of carbon decomposed in soil, but this portion varied with plant productivity and the mycorrhizal carbon uptake strategy simulated. Lower organic matter inputs to soil were largely responsible for reduced soil carbon storage. Using mathematical theory, we demonstrated that biotic interactions affect predictions of ecosystem functions. Specifically, we developed a simple function to model the mycorrhizal switch in function from plant symbiont to decomposer. We show that including mycorrhizal fungi with the flexibility of mutualistic and saprotrophic lifestyles alters predictions of ecosystem function
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