Measurement of muon capture on the proton to 1% precision and determination of the pseudoscalar coupling gP.

The MuCap experiment at the Paul Scherrer Institute has measured the rate Λ(S) of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in a time projection chamber filled with 10-bar, ultrapure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. Λ(S) is determined from the difference between the µ(-) disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2 × 10(10) µ(-) decays, from which we extract the capture rate Λ(S) = (714.9 ± 5.4(stat) ± 5.1(syst)) s(-1) and derive the proton's pseudoscalar coupling g(P)(q(0)(2) = -0.88 m(µ)(2)) = 8.06 ± 0.55.

[Visits to the doctor because of illness or injury of the students of vocational schools who consume or do not consume psychoactive substances (comparative aspects)].

AIM: To elucidate what impact has the use of different narcotic drugs, alcohol and tobacco on the health of students and the risk of injuries. MATERIAL AND METHODS: We carried out a questionnaire survey of the first year students from all six vocational schools of Klaipeda (Lithuania) in 2004, 2006 and 2008. A total of 912 students (507 boys and 405 girls, mean age 17.5 years) were surveyed with an anonymous questionnaire. The findings were analysed with computer soft SPSS (SPSS 16.0 for Windows). RESULTS: The results showed that the use of any psychoactive substances is damaging to health, especially injection and club narcotic drugs. Adolescents addicted to any psychoactive substances more often than non-addicts visited doctor due to illness or injury during the last 12 months. CONCLUSION: Adolescents on illegal drugs, especially boys on injectable narcotic drugs and girls on club drugs were at twice higher risk for disease or injury (odds ratio--OR--3.39, 95% confidence interval--CI--1.25 to 9.19, p = 0.016 and OR--2.38, CI--1.35 to 4.20, p = 0.003, respectively). Tobacco and alcohol consumption did not significantly increase this risk with the exception of tobacco smoking girls. We think it happened because these two addictions are widely spread among large part of the boys from the vocational schools.

Electric potential and bending rigidity of a wormlike particle in electrolyte solution.

Using the linearized Poisson-Boltzmann equation (LPB) we derive an asymptotic expansion for the electrostatic potential of charged torus immersed in solution of an electrolyte in the limit of high salinity and large major radius of the torus. The small parameter of this expansion is the ratio of the Debye length to the minor radius of the torus. We derive asymptotic expressions for the electrostatic free energy and for the electrostatic persistence length of a polyion of a finite thickness. We propose a simple interpolation formula, xi(el)=l(B)(sigma(0)/e)(2)bkappa(D)[1+kappa(D)/(4b)], that gives the electrostatic persistence length in terms of the Debye length kappa(D), the linear charge density (sigma(0)/e), and the thickness of the polyion, 2b. This formula reproduces the exact results from the LPB theory in the limits of high and low salt concentrations. For the entire range of salinities, our formula is in excellent agreement with the numerical LPB results for wormlike particles of varying thickness. For particles of vanishing thickness, this formula reduces to the classical Odijk-Skolnick-Fixman expression.

Measurement of the muon capture rate in hydrogen gas and determination of the proton's pseudoscalar coupling gP.

The rate of nuclear muon capture by the proton has been measured using a new technique based on a time projection chamber operating in ultraclean, deuterium-depleted hydrogen gas, which is key to avoiding uncertainties from muonic molecule formation. The capture rate from the hyperfine singlet ground state of the microp atom was obtained from the difference between the micro(-) disappearance rate in hydrogen and the world average for the micro(+) decay rate, yielding Lambda(S)=725.0+/-17.4 s(-1), from which the induced pseudoscalar coupling of the nucleon, g(P)(q(2)=-0.88m(2)(micro))=7.3+/-1.1, is extracted.

[The clinico-microbiological and epidemiological aspects of hospital infections in a surgical clinic]. / Kliniko-mikrobiologicheskie i épidemiologicheskie aspekty gospital'nykh infektsii v khirurgicheskoi klinike.

Complex clinical and microbiological and epidemiological study of specificity of hospital infections was conducted in surgical clinics of Military and Medical Academy. Analysis of the materials obtained has permitted to develop the classification of agents of modern hospital surgical infections, to study the variety and specificity of forming of microorganism hospital strains. To optimize the system of sanitary and epidemiological inspection on hospital infections and to improve their prophylaxis it is proposed to introduce into the practice of bacteriological laboratories of military medical and prophylactic institutions the quantitative microbiological examinations of clinical material. Besides it is reasonable to have in the stuff of multipurpose military hospitals the post of hospital epidemiologist trained in the actual problems of clinical microbiology, hospital hygiene and surgical infection.

Generalized algorithm for the unified analysis and simultaneous evaluation of geometrical spin-redirection phase and Pancharatnam phase in a complex interferometric system.

To permit unified analysis and simultaneous evaluation of geometrical spin-redirection phase and Pancharatnam phase, the conventional 2 x 2 Jones matrix calculation is generalized and a new scheme of 3 x 3 matrix calculation is proposed. With the proposed algorithm one can trace the polarization state changes and the geometric phase shifts caused by beam propagation along an arbitrary optical path that involves both reflection and refraction at surfaces with Fresnel shift and birefringence.

Observation of the Cabibbo-Suppressed Decay Ξ_{c}

We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ_{c}^{+}→pK^{-}π^{+}. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Σ^{-} beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ_{c}^{+}→Σ^{+}K^{-}π^{+} and Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} are measured to be B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Σ^{+}K^{-}π^{+})=0.22±0.06±0.03 and B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+})=0.20±0.04±0.02, respectively.

Interferometric microimaging based on geometrical spin-redirection phase.

A novel scheme for an interferometric microscope with which to visualize a geometrical spin-redirection phase image that represents the local inclination of microsurface structures of an object is proposed. The observed phase depends on the state of polarization and the optical constants of the object material, which enable one to distinguish the spin-redirection phase from the conventional dynamical-phase. A preliminary experiment was performed, and the phase images obtained were found to be consistent with those predicted by computer simulation based on a theoretical model.