115 research outputs found
Jost Function for Singular Potentials
An exact method for direct calculation of the Jost function and Jost
solutions for a repulsive singular potential is presented. Within this method
the Schrodinger equation is replaced by an equivalent system of linear
first-order differential equations, which after complex rotation, can easily be
solved numerically. The Jost function can be obtained to any desired accuracy
for all complex momenta of physical interest, including the spectral points
corresponding to bound and resonant states. The method can also be used in the
complex angular-momentum plane to calculate the Regge trajectories. The
effectiveness of the method is demonstrated using the Lennard-Jones (12,6)
potential. The spectral properties of the realistic inter-atomic He4-He4
potentials HFDHE2 and HFD-B of Aziz and collaborators are also investigated.Comment: 12 pages, latex, 2 eps-figures, submitted to Phys.Rev.
Occupational Bladder Cancer in a 4,4′-Methylenebis(2-chloroaniline) (MBOCA)-Exposed Worker
A 52-year-old male chemical worker was admitted to the hospital with a history of paroxysmal microscopic hematuria for about 2 years and nocturia with gross hematuria about five times per night for 2 months. He was a nonsmoker and denied a history of any other bladder carcinogen exposure except for occasional pesticide application during agricultural work. Intravenous urogram imaging showed a mass occupying half of the bladder capacity. Cystoscopy revealed a mass over the left dome of the bladder. Cystoscopic biopsy revealed a grade 3 invasive transitional cell carcinoma with marked necrosis. From 1987 until hospital admission in 2001, the patient had worked in a company that produced the 4,4′-methylenebis(2-chloroaniline) (MBOCA) curing agent. He did not wear any personal protective equipment during work. Ambient air MBOCA levels in the purification process area (0.23–0.41 mg/m(3)) exceeded the U.S. Occupational Safety and Health Administration’s permissible exposure level. Urinary MBOCA levels (267.9–15701.1 μg/g creatinine) far exceeded the California Occupational Safety and Health Administration’s reference value of 100 μg/L. This patient worked in the purification process with occupational exposure to MBOCA for 14 years. According to the environmental and biologic monitoring data and latency period, and excluding other potential bladder carcinogen exposure, this worker was diagnosed as having occupational bladder cancer due to high exposure to MBOCA through inhalation or dermal absorption in the purification area. This case finding supports that MBOCA is a potential human carcinogen. Safe use of skin-protective equipment and respirators is required to prevent workers from MBOCA exposure
Comparative structural response of two steel bridges constructed 100 years apart
This paper presents a comparative numerical analysis of the structural behaviour and seismic performance of two existing steel bridges, the Infiernillo II Bridge and the Pinhao Bridge, one located in Mexico and the other in Portugal. The two bridges have similar general geometrical characteristics, but were constructed 100 years apart. Three-dimensional structural models of both bridges are developed and analysed for various load cases and several seismic conditions. The results of the comparative analysis between the two bridges are presented in terms of natural frequencies and corresponding vibration modes, maximum stresses in the structural elements and maximum displacements. The study is aimed at determining the influence of a 1 century period in material properties, transverse sections and expected behaviour of two quite similar bridges. In addition, the influence of the bearing conditions in the global response of the Pinhao Bridge was evaluated
The ^4He trimer as an Efimov system
We review the results obtained in the last four decades which demonstrate the
Efimov nature of the He three-atomic system.Comment: Review article for a special issue of the Few-Body Systems journal
devoted to Efimov physic
Sensitivity of the Earthquake Response of Tall Steel Moment Frame Buildings to Ground Motion Features
Spin-Polarized Atomic Deuterium: Stabilization, Limitations on Density, and Adsorption Energy on Helium
Analysis of the steel braced frames equipped with ADAS devices under the far field records
On the effect of the near field records on the steel braced frames equipped with energy dissipating devices
Performance Evaluation of Shear Links and Orthotropic Bridge Deck Panels for the new San Francisco-Oakland Bay Bridge
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