629,912 research outputs found
The Effect of Radiation on the Stochastic Web
A charged particle circling in a uniform magnetic field and kicked by an
electric field is considered. Under the assumption of small magnetic field, an
iterative map is developed. Comparison between the (relativistic) non-radiative
case and the (relativistic) radiative case shows that in both cases one can
observe a stochastic web structure, and that both cases are qualitatively
similar.Comment: 8 Revtex pages including 4 figure
The effectiveness of origami on overall hand function after injury: A pilot controlled trial
This pilot study measured the effectiveness of using origami to improve the overall hand function of outpatients attending an NHS hand injury unit. The initiative came from one of the authors who had used origami informally in the clinical setting and observed beneficial effects. These observed effects were tested experimentally. The design was a pilot non-randomised controlled trial with 13 participants. Allocation of the seven control group members was based on patient preference. The experimental group members attended a weekly hour of origami for six weeks, in addition to their conventional rehabilitation.
Hand function of all participants was measured using the Jebsen-Taylor Hand Function Test before and after the six-week period, and additional qualitative data were gathered in the form of written evaluations from patients. The quantitative data were analysed using the Mann Whitney U test or Fisherâs exact test. Themes were highlighted from the qualitative data.
The results show that there was a greater difference in the total score of the experimental group using the impaired hand between pre- and post-intervention of 11.8 seconds, compared with 4.3 seconds in the control group, but this was not statistically significant at the 5% level (p=0.06). Additionally, differences in the sub-test scores show a markedly larger improvement in the experimental group. Qualitative data indicate that the experimental group experienced the origami sessions as being enjoyable and beneficial. Further research with a larger sample and randomised group allocation is recommended to verify and expand these preliminary findings
Super-Arrhenius dynamics for sub-critical crack growth in disordered brittle media
Taking into account stress fluctuations due to thermal noise, we study
thermally activated irreversible crack growth in disordered media. The
influence of material disorder on sub-critical growth of a single crack in
two-dimensional brittle elastic material is described through the introduction
of a rupture threshold distribution. We derive analytical predictions for crack
growth velocity and material lifetime in agreement with direct numerical
calculations. It is claimed that crack growth process is inhibited by disorder:
velocity decreases and lifetime increases with disorder. More precisely,
lifetime is shown to follow a super-Arrhenius law, with an effective
temperature theta - theta_d, where theta is related to the thermodynamical
temperature and theta_d to the disorder variance.Comment: Submitted to Europhysics Letter
Study on the spectrum of the injected relativistic protons
About 10TeV gamma-ray emission within 10 pc region from the Galactic Center
had been reported by 4 independent groups. Considering that this TeV gamma-ray
emission is produced via a hadronic model, and the relativistic protons came
from the tidal disruption of stars by massive black holes, we investigate the
spectral nature of the injected relativistic protons required by the hadronic
model. The calculation was carried on the tidal disruption of the different
types of stars and the different propagation mechanisms of protons in the
interstellar medium. Compared with the observation data from HESS, we find for
the best fitting that the power-law index of the spectrum of the injected
protons is about -1.9, when a red giant star is tidally disrupted, and the
effective confinement of protons diffusion mechanism is adopted.Comment: 2 pages, IAU Symposium 25
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