Surface effects on vortex dynamics in thin type-II superconducting stripes with random pinning

We analyze the dynamics of a driven vortex lattice moving in a thin Superconducting stripe. The two dimensional stripe is assumed to be finite in the longitudinal direction, where we take into account the Surface effects, and infinite in the transversal direction. The numerical simulations are performed using the Langevin dynamics, including the vortex-vortex interaction, interaction of vortices with the surface current, vortex images, transport current and randomly distributed pinning centers. We show results for the differential resistivity and the vortex trajectories as a function of the external force. (C) 2004 Elsevier B.V. All rights reserved.

Partial urethral obstruction of rabbit urinary bladder: stereological evidence that the increase in muscle content is mostly driven by changes in number, rather than size, of smooth muscle cells

The effects of partial urethral obstruction on the detrusor muscle of rabbit urinary bladder were investigated using stereological sampling and estimation tools. Twelve female Norfolk rabbits (2.5-3.0 kg body weight) were divided into four groups: 3, 7 and 12 weeks after surgical intervention to produce a standard partial obstruction and unobstructed controls. Following removal, bladder axes (craniocaudal, dorsoventral and laterolateral) and organ weights were recorded. Bladders were prepared for light microscopy by multistage random sampling procedures. Stereological methods were used to estimate the volume of muscle and the packing density and total number of myocyte nuclei in each bladder. We also estimated mean myocyte volume and the mean cross-sectional area and length of myocytes. Group comparisons were made by one-way analysis of variance. Changes in bladder axes were mainly laterolateral and craniocaudal. Mean bladder weight increased roughly six-fold by 3 weeks and 17-fold by 12 weeks and was accompanied, on average, by 12- and 33-fold increases in total muscle volume. These variables did not differ at 3 and 7 weeks post-obstruction. Increases in muscle content were not accompanied by changes in packing densities but were associated with increases in the total numbers of myocyte nuclei (13-fold by 3 weeks, 28-fold by 12 weeks). Mean myocyte volume did not vary significantly between groups but cells in obstructed groups were shorter and wider. These findings support the notion that partial outflow obstruction leads to an increase in the number, but not mean volume, of myocytes. If due solely to myocyte mitosis, the total of 43 x 10(8) cells found at 12 weeks could be generated by the original complement of 15 x 10(7) cells if an average of only 2.1 x 10(6) new cells was produced every hour. In reality, even this modest proliferation rate is unlikely to be achieved because myocyte proliferation rates are very low and it is possible that new myocytes can arise by differentiation of mesenchymal or other precursor cells.

POSITRON-HELIUM SCATTERING IN THE CLOSE-COUPLING APPROACH

We present results for low-energy elastic S-, P-, and D-wave phase shifts, capture and total cross sections of positron-helium scattering with different basis sets in the close coupling approach using realistic wave functions for He(1s1s), He(1s2(1)s), He(1s2(1)p) and positronium (1s) states. A resonance is found in the S-wave capture cross section at 84 eV.

Positronium-alkali-ion scattering in the close-coupling approximation

We present results for low- and medium-energy elastic and capture cross sections for positronium-atom-alkali-ion scattering using the coupled static close-coupling approximation.

Genetic variability in species of bats revealed by RAPD analysis

Random amplified polymorphic DNA molecular marker was utilized as a means of analyzing genetic variability in seven bat species: Molossus molossus, M. rufus, Eumops glaucinus, E. perotis, Myotis nigricans, Eptesicus furinalis, and Artibeus planirostris. The determination of genetic diversity was based on 741 bands produced by a 20-random primer set. Only eight bands were considered monomorphic to one species. The greatest number of bands and the most polymorphic condition were exhibited by M. molossus, followed by M. nigricans, A. planirostris, E. furinalis, E. glaucinus, M. rufus, and E. perotis. Nei's genetic diversity index in the seven species considering the 20 primers was not greater than 0.22, but some primers were capable of detecting values between 0.39 and 0.49. Nei's unbiased genetic distance values and the UPGMA clustering pattern show that M. molossus and M. rufus have a close genetic relationship, unlike that observed between E. perotis and E. glaucinus. The latter was clustered with A. planirostris and E. furinalis. The low values for genetic diversity and distance observed indicate a genetic conservatism in the seven species. The fluorescent in situ hybridization experiments did not confirm a monomorphic condition for the eight bands identified, demonstrating that the monomorphic bands obtained by random amplified polymorphic DNA are insufficient for the identification of bat species.

The use of nonparametric contrasts in one-way layouts and random block designs

Nonparametric simple-contrast estimates for one-way layouts based on Hodges-Lehmann estimators for two samples and confidence intervals for all contrasts involving only two treatments are found in the literature.Tests for such contrasts are performed from the distribution of the maximum of the rank sum between two treatments. For random block designs, simple contrast estimates based on Hodges-Lehmann estimators for one sample are presented. However, discussions concerning the significance levels of more complex contrast tests in nonparametric statistics are not well outlined.This work aims at presenting a methodology to obtain p-values for any contrast types based on the construction of the permutations required by each design model using a C-language program for each design type. For small samples, all possible treatment configurations are performed in order to obtain the desired p-value. For large samples, a fixed number of random configurations are used. The program prompts the input of contrast coefficients, but does not assume the existence or orthogonality among them.In orthogonal contrasts, the decomposition of the value of the suitable statistic for each case is performed and it is observed that the same procedure used in the parametric analysis of variance can be applied in the nonparametric case, that is, each of the orthogonal contrasts has a chi(2) distribution with one degree of freedom. Also, the similarities between the p-values obtained for nonparametric contrasts and those obtained through approximations suggested in the literature are discussed.

Ps-H scattering using the three-state positronium close-coupling approximation

Positronium scattering off a hydrogen target has been studied employing a three-state positronium model close-coupling approximation (CCA) with and without electron exchange. Elastic, excitation and quenching cross sections are reported at low and medium energies. The effect of electron exchange is found to be significant at low energies. The ratio of quenching to the total cross section (the conversion ratio) approaches the value of 0.25 with increase of energy, as expected.

ALTERNATIVE SAMPLING STRATEGY FOR A RANDOM OPTIMIZATION ALGORITHM

Alternative sampling procedures are compared to the pure random search method. It is shown that the efficiency of the algorithm can be improved with respect to the expected number of steps to reach an epsilon-neighborhood of the optimal point.

Synaptonemal polycomplexes in spermatids: a characteristic trait of Orthoptera?

Spermatogenesis was analysed in a cricket, Eneoptera surinamensis (Gryllidae, Orthoptera), using ultrathin serial sections and transmission electron microscopy. Special attention was placed on documentation of the development and structure of synaptonemal polycomplexes (PCs) within spermatid nuclei. Pachytene spermatocytes showed the usual tripartite synaptonemal complexes in the nuclear lumen. PCs were situated close to chromosomes at the periphery of spindles in prometaphase I spermatocytes, where microtubule density was low. The PCs are probably incorporated into the daughter nuclei of both meiotic divisions by adhesion to chromosomes. Finally, PCs end up within spermatid nuclei. Analysis of serial sections through three nuclei of young spermatids revealed at least one PC within each. The PCs were intimately attached to an electrondense spherical nuclear body. This topographical correlation was confirmed through inspection of random sections. The PCs may have an affinity to the spherical bodies. In more developed spermatids, PCs and nuclear bodies were missing. Disassembly products of the PCs may play a role in spermatid maturation. In a series of other Orthoptera species, PCs have been reported to occur in the cytoplasm or the nuclei of spermatids. In most other systematic groups, PCs do not form at all or disassemble earlier. The presence of PCs in young spermatids, therefore, seems to be typical of Orthoptera.

Accuracy assessment of a photogrammetric close-range reconstruction system

Geometric accuracy of a close-range photogrammetric system is assessed in this paper considering surface reconstruction with structured light as its main purpose. The system is based on an off-the-shelf digital camera and a pattern projector. The mathematical model for reconstruction is based on the parametric equation of the projected straight line combined with collinearity equations. A sequential approach for system calibration was developed and is presented. Results obtained from real data are also presented and discussed. Experiments with real data using a prototype have indicated 0.5mm of accuracy in height determination and 0.2mm in the XY plane considering an application where the object was 1630mm distant from the camera.

Random amplification of polymorphic DNA reveals clonal relationships among enteropathogenic Escherichia coli isolated from non-human primates and humans

Enteropathogenic Escherichia coli ( EPEC) strains are important agents of infantile diarrhea all over the world, gaining even greater importance in developing countries. EPEC have also been isolated from various animal species, but most isolates belong to serotypes that differ from those recovered from humans. However, it has been demonstrated that several isolates from non- human primates belong to the serogroups and/ or serotypes related to those implicated in human disease. The objective of this study was to evaluate the genetic differences between thirteen strains isolated from non- human primates and the same number of strains isolated from human infections. Human isolates belonged to the same serogroup/ serotype as the monkey strains and the evaluation was done by analysis of random amplified polymorphic DNA. Dendrogram analysis showed that there was no clustering between human and monkey strains. Human and non- human isolates of the EPEC serotypes O127:H40 and O128:H2 shared 90 and 87% of their bands, respectively, indicating strong genomic similarity between the strains, leading to the speculation that they may have arisen from the same pathogenic clone. To our knowledge, this study is the first one comparing genomic similarity between human and non- human primate strains and the results provide further evidence that monkey EPEC strains correlate with human EPEC, as suggested in a previous investigation.

Magnesium sulphate given topically by iontophoresis for viability of random skin flaps in rats

Our aim was to assess the effects of magnesium sulphate given by iontophoresis on the viability of random skin flaps in rats. Endovenous magnesium sulphate is used to treat pre-eclampsia and diseases of blood vessels. Iontophoresis is an electrotherapeutic method which has shown satisfactory results in controlling ischaemia within the boundaries of the area in which it was given. Forty-five adult male Wistar rats, weighing 300 to 440 g were randomly divided into three groups of 15 animals each: random skin flap (control); random skin flap treated with magnesium sulphate without electrical stimulation; and random skin flap treated with magnesium sulphate with electrical stimulation of 4 mA for 20 minutes. The treatments were applied immediately after the operation and repeated on the following two days. The percentage of necrotic area was measured on the seventh postoperative day using a paper template. For each group, the mean percentage of flap necrosis was as follows: control, 46%; magnesium sulphate without electrical stimulation, 34%; and magnesium sulphate with electrical stimulation, 42%. There was no significant difference among the groups (p=0.18). Magnesium sulphate given by iontophoresis does not increase the viability of random skin flaps in rats.

Biopolymer Random Laser Consisting of Rhodamine 6G and Silica Nanoparticles Incorporated to Bacterial Cellulose

We demonstrate random lasing action in a biopolymer that has large potential for medical applications. The novel random laser consists of nanofibers of bacterial cellulose impregnated with silica nanoparticles and Rhodamine 6G.