Studies for the construction of the 100 m telescope

Construction of 100-M telescope for radio astronom

Isoscalar off-shell effects in threshold pion production from pd collisions

We test the presence of pion-nucleon isoscalar off-shell effects in the $pd\to \pi^+ t$ reaction around the threshold region. We find that these effects significantly modify the production cross section and that they may provide the missing strength needed to reproduce the data at threshold.Comment: 6 pages, REVTeX, twocolumn, including 3 figures (Postscript), uses psfig, updated and extended versio

Virtual-pion and two-photon production in pp scattering

Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contribution. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

On the Predicted and Observed Color Boundaries of the RR Lyrae Instability Strip as a Function of Metallicity

The purpose of the paper is to predict the temperature at the fundamental blue edge (FBE) of the instability strip for RR Lyrae (RRL) variables from the pulsation equation that relates temperature to period, luminosity, and mass. Modern data for the correlations between period, luminosity, and metallicity at the FBE for field and cluster RRL are used for the temperature calculation. The predicted temperatures are changed to B-V colors using an adopted color transformation. The predicted temperatures at the FBE become hotter as [Fe/H] changes from 0 to -1.5, and thereafter cooler as the metallicity decreases to -2.5 and beyond. The temperature range over this interval of metallicity is $\Delta$log $T_e$ = 0.04, or 640 K at 6900K. The predicted color variation is at the level of 0.03 mag in B-V. The predictions are compared with the observed RRL colors at the FBE for both the field and cluster variables, showing general agreement at the level of 0.02 mag in (B-V)$_o$, which, however, is the uncertainty of the reddening corrections. The focus of the problem is then reversed by fitting a better envelope to the observed FBE relation between color and metallicity for metallicities smaller than -1.8 which, when inserted in the pulsation equation, gives a non-linear calibration ....Comment: 34 pages, 11 figures, 2 tables. To appear in March 2006 A

A unitary model for meson-nucleon scattering

In an effective Lagrangian model employing the K-matrix approximation we extract nucleon resonance parameters. To this end we analyze simultaneously all available data for reactions involving the final states $\pi N$, $\pi\pi N$, $\eta N$ and $K \Lambda$ in the energy range $m_N + m_{\pi} \le \sqrt s \le 1.9$ GeV. The background contributions are generated consistently from the relevant Feynman amplitudes, thus significantly reducing the number of free parameters.Comment: Revised version. 60 pages, 17 figures. Two figures and a short discussion (\pi N \to \eta N, K \Lambda amplitudes) added, typos and minor errors in the citations correcte

Isocalar Roper excitation in the pp --> pp pi0 reaction close to threshold

A new mechanism for the pp --> pp pi0 reaction close to threshold is suggested coming from the isoscalar excitation of the Roper and its decay into N(pi pi)S-wave, with one of the pi0 emitted and the other one reabsorbed on the second nucleon. The mechanism can lead to important interference with other mechanisms and, together with experiment, serves to exclude large ranges of the 2pi N* decay parameters allowed by the N* partial decay widths.Comment: 11 LaTeX pages, 4 postscript figure

Postoperative wound infections. Pathophysiology, risk factors and preventive concepts

Postoperative wound infections are the third most common type of nosocomial infection in German emergency hospitals after pneumonia and urinary infections. They are associated with increased morbidity and mortality, prolonged hospital stay and increased costs. The most important risk factors include the microbiological state of the skin surrounding the incision, delayed or premature prophylaxis with antibiotics, duration of surgery, emergency surgery, poorly controlled diabetes mellitus, malignant disease, smoking and advanced age. Anesthesiological measures to decrease the incidence of wound infections are maintaining normothermia, strict indications for allogenic blood transfusions and timely prophylaxis with antibiotics. Blood glucose concentrations should be kept in the range of 8.3-10 mmol/l (150-180 mg/dl) as lower values are associated with increased complications. Intraoperative and postoperative hyperoxia with 80% O(2) has not been shown to effectively decrease wound infections. The application of local anesthetics into the surgical wound in clinically relevant doses for postoperative analgesia does not impair wound healing