1,273 research outputs found
Reversing a granular flow on a vibratory conveyor
Experimental results are presented on the transport properties of granular
materials on a vibratory conveyor. For circular oscillations of the shaking
trough a non-monotonous dependence of the transport velocity on the normalized
acceleration is observed. Two maxima are separated by a regime, where the
granular flow is much slower and, in a certain driving range, even reverses its
direction. A similar behavior is found for a single solid body with a low
coefficient of restitution, whereas an individual glass bead of 1 mm diameter
is propagated in the same direction for all accelerations.Comment: 4 pages, 5 figures, submitted to Applied Physics Letter
In situ investigations on the respiration and behaviour of the eelpout Zoarces viviparus under short-term hypoxia
Respiration and activity of eelpouts Zoarces viviparus L. were measured in an underwater respiration chamber in Kiel Bay (Germany) under short-term hypoxia. Respiration and swimming
activity both declined almost continuously with decreasing oxygen saturation..
The Lyapunov exponent in the Sinai billiard in the small scatterer limit
We show that Lyapunov exponent for the Sinai billiard is with where
is the radius of the circular scatterer. We consider the disk-to-disk-map
of the standard configuration where the disks is centered inside a unit square.Comment: 15 pages LaTeX, 3 (useful) figures available from the autho
Combination therapy with bosentan and sildenafil for refractory digital ulcers and Raynaud’s phenomenon in a 30-year-old woman with systemic sclerosis: Case report and literature review
BACKGROUND:
Systemic sclerosis is a rare autoimmune disease characterized by skin and organ fibrosis, and vasculopathy. Raynaud’s phenomenon is almost universally present in systemic sclerosis and can be the most debilitating symptom. Raynaud’s phenomenon may lead to the development of digital ulcers, potentially complicated by infection, tissue necrosis, and auto-amputation. Recommended treatments have variable efficacy.
METHODS:
We report the case of a 30-year-old woman with diffuse systemic sclerosis suffering from severe Raynaud’s phenomenon and digital ulcers with digital tissue necrosis who was treated with combination therapy of an endothelin receptor antagonist and phosphodiesterase 5 inhibitor. In addition, we reviewed the literature on the topic.
RESULTS:
Previous therapy with calcium-channel blockers, intravenous iloprost, and bosentan had all failed to control symptoms. We added sildenafil in combination with bosentan and observed a rapid and sustained treatment effect. Raynaud’s phenomenon severity, number of attacks, and attack duration decreased within 2 weeks of initiating treatment. Furthermore, this resulted in the healing of established digital ulcers.
CONCLUSION:
Our case report suggests that combination therapy may be a feasible treatment for the most severely affected and refractory patients. In our literature review, we found one retrospective study and three additional cases with similarly encouraging results
Fluctuations in the level density of a Fermi gas
We present a theory that accurately describes the counting of excited states
of a noninteracting fermionic gas. At high excitation energies the results
reproduce Bethe's theory. At low energies oscillatory corrections to the
many--body density of states, related to shell effects, are obtained. The
fluctuations depend non-trivially on energy and particle number. Universality
and connections with Poisson statistics and random matrix theory are
established for regular and chaotic single--particle motion.Comment: 4 pages, 1 figur
Challenges to Political Campaigns in the Media: Commercialization, Framing, and Personalization
Due to an increasing interdependence between mass communication and political processes, the role of media in political campaigns generated much debate.In this paper, we identify commercialization, framing and personalization as three key challenges to the way the media face political campaigns. We theoretically derive three hypotheses, one for each of those challenges. Based on data from expert interviews as well as from a content analysis, the validity of each hypothesis is surveyed.
The results do not confi rm an assumed lack of providing campaign relevant news in the media coverage as proposed by considering the media as purely commercially driven organizations. Further they demonstrate the use of different frames for the presentation of competing positions in a political debate. Finally, personalization appears as an important strategy of news selection, focusing on a small number of prominent actors
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