The external gamma radiation environment from the Kiwi Phoebus, and Pewee reactors

During the past few years, ground tests of high-powered propulsion-prototype reactors have provided several opportunities to observe the external radiation environment. Reactor tests have been conducted in free air and inside of open well shields. Measurements were taken over distances ranging from contact with the pressure vessel out to greater than 5000' both during operation and after shutdown. Some measurements characteristic of each of the systems are presented and compared with results of calculations

Quasilinearization Method and Summation of the WKB Series

Solutions obtained by the quasilinearization method (QLM) are compared with the WKB solutions. Expansion of the $p$-th QLM iterate in powers of $\hbar$ reproduces the structure of the WKB series generating an infinite number of the WKB terms with the first $2^p$ terms reproduced exactly. The QLM quantization condition leads to exact energies for the P\"{o}schl-Teller, Hulthen, Hylleraas, Morse, Eckart potentials etc. For other, more complicated potentials the first QLM iterate, given by the closed analytic expression, is extremely accurate. The iterates converge very fast. The sixth iterate of the energy for the anharmonic oscillator and for the two-body Coulomb Dirac equation has an accuracy of 20 significant figures

Exact two-particle eigenstates in partially reduced QED

We consider a reformulation of QED in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. It is shown that exact few-fermion eigenstates of the resulting Hamiltonian can be obtained in the canonical equal-time formalism for the case where there are no free photons. These eigenstates lead to two- and three-body Dirac-like equations with electromagnetic interactions. Perturbative and some numerical solutions of the two-body equations are presented for positronium and muonium-like systems, for various strengths of the coupling.Comment: 33 pages, LaTex 2.09, 4 figures in EPS forma

The bound mu+ mu- system

We consider the hyperfine structure, the atomic spectrum and the decay channels of the bound mu+ mu- system (dimuonium). The annihilation lifetimes of low-lying atomic states of the system lie in the nanosecond range range. The decay rates could be measured by detection of the decay products (high energy photons or electron-positron pairs). The hyperfine structure splitting of the dimuonic system and its decay rate are influenced by electronic vacuum polarization effects in the far time-like asymptotic region. This constitutes a previously unexplored kinematic regime. We evaluate next--to-leading order radiative corrections to the decay rate of low-lying atomic states. We also obtain order alpha^5 corrections to the hyperfine splitting of the 1S and 2S levels.Comment: 10 figures (eps format) attached, Scheduled tentatively by PRA for Nov/Dec 199

Strong Relationship Between Vascular Function in the Coronary and Brachial Arteries: A Clinical Coming of Age for the Updated Flow-Mediated Dilation Test?

Early detection of coronary artery dysfunction is of paramount cardiovascular clinical importance, but a noninvasive assessment is lacking. Indeed, the brachial artery flow-mediated dilation test only weakly correlated with acetylcholine-induced coronary artery function (r=0.36). However, brachial artery flow-mediated dilation methodologies have, over time, substantially improved. This study sought to determine if updates to this technique have improved the relationship with coronary artery function and the noninvasive indication of coronary artery dysfunction. Coronary artery and brachial artery function were assessed in 28 patients referred for cardiac catheterization (61±11 years). Coronary artery function was determined by the change in artery diameter with a 1.82 μg/min intracoronary acetylcholine infusion. Based on the change in vessel diameter, patients were characterized as having dysfunctional coronary arteries (\u3e5% vasoconstriction) or relatively functional coronary arteries (\u3c5% vasoconstriction). Brachial artery function was determined by flow-mediated dilation, adhering to current guidelines. The acetylcholine-induced change in vessel diameter was smaller in patients with dysfunctional compared with relatively functional coronary arteries (−11.8±4.6% versus 5.8±9.8%, P\u3c0.001). Consistent with this, brachial artery flow-mediated dilation was attenuated in patients with dysfunctional compared with relatively functional coronaries (2.9±1.9% versus 6.2±4.2%, P=0.007). Brachial artery flow-mediated dilation was strongly correlated with the acetylcholine-induced change in coronary artery diameter (r=0.77, P\u3c0.0001) and was a strong indicator of coronary artery dysfunction (receiver operator characteristic=78%). The current data support that updates to the brachial artery flow-mediated dilation technique have strengthened the relationship with coronary artery function, which may now provide a clinically meaningful indication of coronary artery dysfunction

Semi-Analytic Approach to Higher-Order Corrections in Simple Muonic Bound Systems: Vacuum Polarization, Self-Energy and Radiative-Recoil

The current discrepancy of theory and experiment observed recently in muonic hydrogen necessitates a reinvestigation of all corrections to contribute to the Lamb shift in muonic hydrogen muH, muonic deuterium muD, the muonic 3He ion, as well as in the muonic 4He ion. Here, we choose a semi-analytic approach and evaluate a number of higher-order corrections to vacuum polarization (VP) semi-analytically, while remaining integrals over the spectral density of VP are performed numerically. We obtain semi-analytic results for the second-order correction, and for the relativistic correction to VP. The self-energy correction to VP is calculated, including the perturbations of the Bethe logarithms by vacuum polarization. Subleading logarithmic terms in the radiative-recoil correction to the 2S-2P Lamb shift of order alpha (Zalpha)^5 mu^3 ln(Zalpha)/(m_mu m_N) are also obtained. All calculations are nonperturbative in the mass ratio of orbiting particle and nucleus.Comment: 10 pages; svjour style; to appear in the European Physical Journal

Protection of pregnant women at work in Switzerland: implementation and experiences of maternity protection legislation

Objectives. Like most industrialized countries, Switzerland has introduced legislation to protect the health of pregnant workers and their unborn children from workplace hazards. This study aims to assess legislation’s degree of implementation in the French-speaking part of Switzerland and understand the barriers to and resources supporting its implementation. Methods. Data were collected using mixed methods: (1) an online questionnaire send to 333 gynecologist-obstetricians (GOs) and 637 midwives; (2) exploratory semi-structured interviews with 5 workers who had had a pregnancy in the last 5 years. Results. Questionnaire response rates were 32% for GOs and 54% for midwives. Data showed that several aspects of the implementation of maternity protection policies could be improved. Where patients encounter workplace hazards, GOs and midwives estimated that they only received a risk assessment from the employer in about 5% and 2% of cases, respectively. Preventive leave is underprescribed: 32% of GOs reported that they “often” or “always” prescribed preventive leave in cases involving occupational hazards; 58% of GOs reported that they “often” or “always” prescribed sick leave instead. Interviews with workers identified several barriers to the implementation of protective policies in workplaces: a lack of information about protective measures and pregnancy rights; organizational problems triggered by job and schedule adjustments; and discrepancies between some safety measures and their personal needs. Conclusions. Results demonstrate the need to improve the implementation and appropriateness of maternity protection legislation in Switzerland. More research is required to identify the factors affecting its implementation

Adipose triglyceride lipase (ATGL) expression in human skeletal muscle is type I (oxidative) fiber specific

Accumulation of triacylglycerol (TAG) and lipid intermediates in skeletal muscle plays an important role in the etiology of insulin resistance and type 2 diabetes mellitus. Disturbances in skeletal muscle lipid turnover and lipolysis may contribute significantly to this. So far, knowledge on the regulation of muscle lipolysis is limited. Recently the identification of a new lipase was reported: adipose triglyceride lipase (ATGL). ATGL deficient animals show significant lipid accumulation in skeletal muscle, which may indicate that ATGL plays a pivotal role in skeletal muscle lipolysis. However, until now, it is still unknown whether ATGL protein is expressed in human skeletal muscle. Therefore, the aim of the present study was to investigate whether ATGL is expressed at the protein level in human skeletal muscle, and to examine whether its expression is fiber-type specific. To accomplish this, we established an imunohistochemical and immunofluorescent staining procedure to study ATGL protein expression in relation to fiber type in human vastus lateralis muscle of eight male subjects (BMI range: 21.0–34.5 kg/m2 and age: 38–59 years). In the present paper we report for the first time that ATGL protein is indeed expressed in human skeletal muscle. Moreover, ATGL is exclusively expressed in type I (oxidative) muscle fibers, suggesting a pivotal role for ATGL in intramuscular fatty acid handling, lipid storage and breakdown