Quantum radiation pressure on a moving mirror at finite temperature

We compute the radiation pressure force on a moving mirror, in the nonrelativistic approximation, assuming the field to be at temperature $T.$ At high temperature, the force has a dissipative component proportional to the mirror velocity, which results from Doppler shift of the reflected thermal photons. In the case of a scalar field, the force has also a dispersive component associated to a mass correction. In the electromagnetic case, the separate contributions to the mass correction from the two polarizations cancel. We also derive explicit results in the low temperature regime, and present numerical results for the general case. As an application, we compute the dissipation and decoherence rates for a mirror in a harmonic potential well.Comment: Figure 3 replaced, changes mainly in Sections IV and V, new appendix introduced. To appear in Physical Review

Antiplatelet agents and/or anticoagulants are not associated with worse outcome following nonvariceal upper gastrointestinal bleeding

BACKGROUND: Nonvariceal upper gastrointestinal bleeding emerges as a major complication of using antiplatelet agents and/or anticoagulants and represents a clinical challenge in patients undergoing these therapies. AIM: To characterize patients with nonvariceal upper gastrointestinal bleeding related to antithrombotics and their management, and to determine clinical predictors of adverse outcomes. METHODS: Retrospective cohort of adults who underwent upper gastrointestinal endoscopy after nonvariceal upper gastrointestinal bleeding from 2010 to 2012. The outcomes were compared between patients exposed and not exposed to antithrombotics. RESULTS: Five hundred and forty-eight patients with nonvariceal upper gastrointestinal bleeding (67% men; mean age 66.5 ± 16.4 years) were included, of which 43% received antithrombotics. Most patients had comorbidities. Peptic ulcer was the main diagnosis and endoscopic therapy was performed in 46% of cases. The 30-day mortality rate was 7.7% (n = 42), and 36% were bleeding-related. The recurrence rate was 9% and 14% of patients with initial endoscopic treatment needed endoscopic retreatment. There were no significant differences between the exposed and non-exposed groups in most outcomes. Co-morbidities, hemodynamic instability, high Rockall score, low hemoglobin (7.76 ± 2.72 g/dL) and higher international normalized ratio (1.63 ± 1.13) were associated significantly with mortality in a univariate analysis. CONCLUSIONS: Adverse outcomes were not associated with antithrombotic use. The management of nonvariceal upper gastrointestinal bleeding constitutes a challenge to clinical performance optimization and clinical cooperation.info:eu-repo/semantics/publishedVersio

Establishment of Tanzania Grass Pasture Using Millet as a Companion Crop

Forage yield and quality of millet [Pennisetum glaucum (L.) R. Br.] and tanzania grass (Panicum maximum Jacq. cv. Tanzania I) were evaluated when grown in mixture. The treatments evaluated were four seed mixture combinations, based on a standard sowing density of 8 kg.ha-1, of tanzania grass/millet (08/00; 05/03; 04/04 and 03/05 kg.ha-1) and three cutting frequencies (1 cutting – 100th day after sowing; 2 cuttings – 50th and 100th days after sowing and 3 cuttings – 40th, 70th and 100th days after sowing), in a randomized complete block design, with four replications, in a split-plot scheme. Sowing densities were allocated in the main plots (5.0 x 12.0 m, each) and cutting frequencies in the subplots (5.0 x 4.0 m, each). The yields of DM of millet combined with tanzania grass were higher than that for pure tanzania grass stand. The CP increased whereas NDF and ADF decreased for both millet and tanzania grass with increasing cutting frequency. There was a small decrease in CP content when millet was in association with tanzania grass. According to these results, it was concluded that it is feasible the establishment of tanzania grass pasture using millet as a companion crop

Performance of Millet Cultivars in Succession to Field Crop of Beans in Southern Portion of State of Minas Gerais - Brazil

This trial was carried out at the Department of Animal Science - Universidade Federal de Lavras (UFLA), from February to June, 1997. It was evaluated the performance of three millet [Pennisetum glaucum (L.) R. Br.] cultivars, as a second crop (Common, BN 2 and CMS 02) and four sowing dates (02/22, 03/14, 04/03 and 04/23). The three millet cultivars were sown after a cropping of beans (Phaseolus vulgaris L.) by the end of the rainy season, with no additional fertilization. It was used the randomized block design in a split-plot scheme, allocating the sowing dates on the main plots and the cultivars on the subplots. There was a significant effect of sowing dates upon tiller height and density of millet cultivars. The residual fertilization of the rainy season beans’ crop was not enough to allow a millet to reach high yields. The average yield value for the three cultivars and four sowing dates was 3.27 t.ha-1 of DM. For the region of Lavras-MG, millet can be used in a succession cultivation, as the second crop, using cultivars Common and BN 2 sowed up to mid-March and it is necessary to use at least nitrogen and potassium for topdress fertilization

Dynamical Casimir effect with Dirichlet and Neumann boundary conditions

We derive the radiation pressure force on a non-relativistic moving plate in 1+1 dimensions. We assume that a massless scalar field satisfies either Dirichlet or Neumann boundary conditions (BC) at the instantaneous position of the plate. We show that when the state of the field is invariant under time translations, the results derived for Dirichlet and Neumann BC are equal. We discuss the force for a thermal field state as an example for this case. On the other hand, a coherent state introduces a phase reference, and the two types of BC lead to different results.Comment: 12 page