Integral representation of one dimensional three particle scattering for delta function interactions

The Schr\"{o}dinger equation, in hyperspherical coordinates, is solved in closed form for a system of three particles on a line, interacting via pair delta functions. This is for the case of equal masses and potential strengths. The interactions are replaced by appropriate boundary conditions. This leads then to requiring the solution of a free-particle Schr\"{o}dinger equation subject to these boundary conditions. A generalized Kontorovich - Lebedev transformation is used to write this solution as an integral involving a product of Bessel functions and pseudo-Sturmian functions. The coefficient of the product is obtained from a three-term recurrence relation, derived from the boundary condition. The contours of the Kontorovich-Lebedev representation are fixed by the asymptotic conditions. The scattering matrix is then derived from the exact solution of the recurrence relation. The wavefunctions that are obtained are shown to be equivalent to those derived by McGuire. The method can clearly be applied to a larger number of particles and hopefully might be useful for unequal masses and potentials.Comment: 18 pages, 2 figures, to be published in J. Math. Phy

S-matrix poles and the second virial coefficient

For cutoff potentials, a condition which is not a limitation for the calculation of physical systems, the S-matrix is meromorphic. We can express it in terms of its poles, and then calculate the quantum mechanical second virial coefficient of a neutral gas. Here, we take another look at this approach, and discuss the feasibility, attraction and problems of the method. Among concerns are the rate of convergence of the 'pole' expansion and the physical significance of the 'higher' poles.Comment: 20 pages, 8 tables, submitted to J. Mol. Phy

Three Bosons in One Dimension with Short Range Interactions I: Zero Range Potentials

We consider the three-boson problem with $\delta$-function interactions in one spatial dimension. Three different approaches are used to calculate the phase shifts, which we interpret in the context of the effective range expansion, for the scattering of one free particle a off of a bound pair. We first follow a procedure outlined by McGuire in order to obtain an analytic expression for the desired S-matrix element. This result is then compared to a variational calculation in the adiabatic hyperspherical representation, and to a numerical solution to the momentum space Faddeev equations. We find excellent agreement with the exact phase shifts, and comment on some of the important features in the scattering and bound-state sectors. In particular, we find that the 1+2 scattering length is divergent, marking the presence of a zero-energy resonance which appears as a feature when the pair-wise interactions are short-range. Finally, we consider the introduction of a three-body interaction, and comment on the cutoff dependence of the coupling.Comment: 9 figures, 2 table

Exact ground states for the four-electron problem in a Hubbard ladder

The exact ground state of four electrons in an arbitrary large two leg Hubbard ladder is deduced from nine analytic and explicit linear equations. The used procedure is described, and the properties of the ground state are analyzed. The method is based on the construction in r-space of the different type of orthogonal basis wave vectors which span the subspace of the Hilbert space containing the ground state. In order to do this, we start from the possible microconfigurations of the four particles within the system. These microconfigurations are then rotated, translated and spin-reversed in order to build up the basis vectors of the problem. A closed system of nine analytic linear equations is obtained whose secular equation, by its minimum energy solution, provides the ground state energy and the ground state wave function of the model.Comment: 10 pages, 7 figure

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Quinolones in the treatment of Salmonella carriers.

Infections caused by Salmonella typhi are commonly followed by a chronic carrier state despite positive clinical and initial bacteriologic responses. The use of primary antibiotics like chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole has several major drawbacks, including in some instances the failure to prevent the carrier state. The appearance worldwide of strains with multiple resistance to the most commonly used regimens has prompted the search for new forms of therapy. Among the agents studied have been third-generation cephalosporins and quinolones, which are active in vitro against bacterial enteropathogens like S. typhi. Resolution of chronic carriage of S. typhi and other salmonellae is difficult, and regimens commonly fail (including those that combine antibiotic administration with removal of the gallbladder). In addition to being active in vitro against Salmonella species, the newer quinolones adequately penetrate the intestinal lumen, liver, bile, and gallbladder. Initial experience with norfloxacin and ciprofloxacin in oral treatment of the chronic S. typhi carrier state in adults has been promising

Asymptomatic Bacteriuria (AB) and pyuria in the elderly ambulatory women

Bacteriuria has come to be synonymous of urinary tract infection (UTI), although this approach has never been validated with AB in elderly women. In the absence of symptoms, pyuria is the most suggestive factor of true urinary tract asymptomatic infection. Objective: To determine the prevalence and microbiological differences between AB in elderly ambulatory women with and without pyuria. Methods: During a 12-month period, from January to December of 1995, a cross-sectional study of elderly ambulatory women residing in 7 nursing homes was undertaken. All elderly ambulatory women without symptoms of UTI were evaluated for bacteriuria and pyuria. Results: Of 178 elderly women, AB was found in 44 (24.7%). The mean age of those with bacteriuria was 81±8 years whereas the mean age of those without bacteriuria, was 78±9 years;P <0.050. The association between bacteriuria and pyuria was found in 77%. The presence of pyuria had a sensitivity of 61% for bacteriuria, with a specificity of 91%. The positive predictive value for the presence of pyuria predicting those with bacteriuria was 69.2% and the negative predictive value for the absence of pyuria predicting those without bacteriuria was 87.7%. Escherichia coli was the most common organism isolated in 81.8% women. Conclusion: In elderly women with AB, bacteriuria associated with pyuria should be the diagnostic criterion for infection. Women without bacteriuria but with pyuria should be studied for other causes of tract urinary inflammation

Asymptomatic bacteriuria and inflammatory response to urinary tract infection of elderly ambulatory women in nursing homes

Background. Bacteriuria ? 105 CFU/ml is evidence of urinary tract infection in the absence of associated signs or symptoms. The presence of pyuria with asymptomatic bacteriuria established the response of elderly women against microorganisms capable of causing invasiveness or tissue injury of the urinary tract. Methods. The association between bacteriuria and pyuria was determined in 178 elderly, ambulatory women without symptoms of urinary tract infection in seven nursing homes. Urine culture results were subsequently analyzed in conjunction with absolute leukocyte count in urine. In this cross-sectional study, asymptomatic bacteriuria in elderly women was classified with and without pyuria. Results. The prevalence of asymptomatic bacteriuria was found in 44 (24.7%) elderly women. The presence of pyuria had a sensitivity of 63.6% for bacteriuria and a specificity of 91%. The positive predictive value for the presence of pyuria predicting those with bacteriuria was 70%, and the negative predictive value for the absence of pyuria predicting those without bacteriuria was 88.4%. Escherichia coli was the most common organism isolated in 81.8% of the women. Conclusions. Bacteriuria ? 105 CFU/ml associated with pyuria was detected in 77% of elderly women with asymptomatic urinary tract infections. Bacteriuria of &lt; 105 CFU/ml with pyuria proves less sensitive as an indicator of urinary tract infection. Elderly women with pyuria but without bacteriuria should be studied for other causes of urinary tract inflammation