Analytic Potential Energy Functions for Aluminum Clusters

Nineteen analytic potential energy functions (PEFs) for aluminum (three pairwise additive ones, six nonpairwise additive ones with three-body terms, and ten embedded atom-type PEFs) were obtained from the literature. The PEFs were tested and reparametrized using a diverse training set that includes 20 potential energy curves and a total of 224 geometries for five aluminum clusters AlN (N) 2, 3, 4, 7, and 13) computed using hybrid density functional theory, as well as the experimental face-centered cubic cohesive energy and lattice constant. The best PEFs from the literature have mean unsigned errors (MUEs) over the clusters in the data set of ∼0.12 eV/atom. The best reparametrized PEFs from the literature have MUEs of 0.06 eV/atom. The data set is also used to develop, parametrize, and systematically study the effectiveness of several functional forms designed specifically to model many-body effects in clusters, including bond angle, screening, and coordination number effects; a total of eighteen new PEFs are proposed and tested. The best potential overall has an MUE of 0.05 eV/atom, explicitly includes screening and coordination number effects, features linear scaling, and incorporates the accurate two-body and bulk limits. I

Asymptomatic bacteriuria in freely voiding elderly subjects - Long-term continuous vs pulse treatment with ofloxacin

The aim of this open, randomised study was the comparison of 3-month continuous (group A, n = 34) vs pulse oral ofloxacin therapy (group B, n = 33) in eliminating asymptomatic bacteriuria over 3 further months in 64 freely voiding, ambulant, very old subjects (mean age 83 years). A positive (group C, n = 29) and a negative control (group D, n = 40) were run simultaneously; two subjects in group A were withdrawn because of adverse effects. During therapy 86.7% of 30 cultures, 84.4% of 32 cultures and 24.1% of 29 cultures in groups A, B and C, respectively, had sterile urine (A + B vs C: p < 0.001), whereas 12.8% of 39 cultures (group D) developed positive urine. At 3 months post-therapy 57.2%, 53.1%, 25.9% and 84.2% of 28, 32, 27 and 38 cultures, respectively, of the above groups remained free of infection (A + B vs C: p < 0.012); >50% of positive cultures in groups A + B were due to new microorganisms, resistant to ofloxacin. Mild decreases in serum creatinine occurred in the treated subjects; haematocrit, serum bilirubin, blood urea, and SGPT were not affected. No deterioration in mobility occurred in any group, and the overall mortality (5 deaths) not connected with underlying urinary tract infection was low. It was concluded that: (a) ofloxacin pulse therapy was about equal to a continuous regimen in eliminating bacteriuria (>80% sterile urine) for 3 months, with negative cultures at a 3-month follow-up in greater than or equal to 50%; (b) recurrences were caused chiefly by ofloxacin-resistant organisms; (c) serum creatinine indicated a trend towards lower values in the treated groups; (d) compliance was better and costs were much less in the pulse therapy group. Thus, if required, 3-month pulse therapy can be safely used to keep the urinary tract free of infecting microorganisms