Nonequilibrium critical dynamics of the relaxational models C and D

We investigate the critical dynamics of the $n$-component relaxational models C and D which incorporate the coupling of a nonconserved and conserved order parameter S, respectively, to the conserved energy density rho, under nonequilibrium conditions by means of the dynamical renormalization group. Detailed balance violations can be implemented isotropically by allowing for different effective temperatures for the heat baths coupling to the slow modes. In the case of model D with conserved order parameter, the energy density fluctuations can be integrated out. For model C with scalar order parameter, in equilibrium governed by strong dynamic scaling (z_S = z_rho), we find no genuine nonequilibrium fixed point. The nonequilibrium critical dynamics of model C with n = 1 thus follows the behavior of other systems with nonconserved order parameter wherein detailed balance becomes effectively restored at the phase transition. For n >= 4, the energy density decouples from the order parameter. However, for n = 2 and n = 3, in the weak dynamic scaling regime (z_S <= z_rho) entire lines of genuine nonequilibrium model C fixed points emerge to one-loop order, which are characterized by continuously varying critical exponents. Similarly, the nonequilibrium model C with spatially anisotropic noise and n < 4 allows for continuously varying exponents, yet with strong dynamic scaling. Subjecting model D to anisotropic nonequilibrium perturbations leads to genuinely different critical behavior with softening only in subsectors of momentum space and correspondingly anisotropic scaling exponents. Similar to the two-temperature model B the effective theory at criticality can be cast into an equilibrium model D dynamics, albeit incorporating long-range interactions of the uniaxial dipolar type.Comment: Revtex, 23 pages, 5 eps figures included (minor additions), to appear in Phys. Rev.

Novel universality classes of coupled driven diffusive systems

Motivated by the phenomenologies of dynamic roughening of strings in random media and magnetohydrodynamics, we examine the universal properties of driven diffusive system with coupled fields. We demonstrate that cross-correlations between the fields lead to amplitude-ratios and scaling exponents varying continuosly with the strength of these cross-correlations. The implications of these results for experimentally relevant systems are discussed.Comment: To appear in Phys. Rev. E (Rapid Comm.) (2003

The application of immunohistochemistry as a research technique in veterinary medical schools in Nigeria

Immunohistochemistry involves the use of commercially prepared colour labelled antibodies to detect the presence and distribution of specific cellular proteins known as antigens. It is a diagnostic and research technique employed in medicine, but may have limited veterinary medical application in Nigeria. The present paper accessed the level of awareness and application of immunohistochemistry as a research technique among staff of the veterinary medical schools in Nigeria. As at the time of the study, ten veterinary schools were accredited by the Veterinary Council of Nigeria, thus used for the analysis. Respondents to a structured questionnaire from the veterinary schools included laboratory technologists and academic staff of the departments of veterinary anatomy, pathology and public health. Design of the questions progressed from mere awareness to theoretical and practical knowledge of the technique. Although 93.33 % of respondents who are academic staff were aware of the technique, and an equally high percentage of those aware of the technique have varying levels of theoretical knowledge, only 32.65 % of these respondents have practical experience of immunohistochemistry technique. Similarly, among the laboratory technologists who were aware of the technique, only 34.78 % have actively conducted it. Respondents of the veterinary anatomy specialty had the highest percentage of practical knowledge. Results also indicated that there was only one veterinary medical school with a functional immunohistochemistry laboratory in Nigeria. The paper recommended, among other things, the introduction of immunohistochemistry as a practical course in the curriculum of the veterinary schools in Nigeria.Keywords: Immunohistochemistry; Nigerian veterinary schools; NU

Etiology and antibiotic susceptibility pattern of community-acquired urinary tract infection in Jos metropolis

Community-acquired urinary tract infections occur in individuals not admitted in hospital prior to development of the symptoms of the infection. It occurs mostly in women and caused by Escherichia coli. The aim of this study was to determine the prevalence of urinary tract infection among individuals residing within Jos metropolis. A single voided aseptically collected mid-stream urine (MSU) was obtained from 276 patients at the outpatient unit of Jos University Teaching Hospital (JUTH). These samples were processed immediately using standard wire loop method in medical microbiology laboratory in JUTH. Demographic data were collected by administering a structured questionnaire to the study participants. Data collected were analyzed by EPI info statistical package version 3.5.1. Out of the 276 individuals who participated in the study 52 (18.8%) were positive for urinary tract infection. The study revealed that female participants had the highest occurrence 40 (21.3%) of infection, while male participants had 12 (13.6%). Escherichia coli was the most frequently isolated uropathogen with a prevalence of 20 (38.5%). Married individuals 35 (27.3%) had a higher occurrence of infection compared to singles 17 (11.5%), there was no significant difference in occurrence of infection between married and singles p=0.101 (P&gt;0.05) in the study. The present study revealed a prevalence of 18.8%, with female participants having the highest occurrence of infection. Streptomycin showed the highest susceptibility to bacteria isolates while the least susceptibility was observed with augmentin. Rational use of antibiotics with regular antibiotics susceptibility surveillance studies is recommended to maintain high antibiotic therapeutic profile.Keywords: Community-acquired urinary tract infections, Escherichia coli, Significant isolate

Reaction-controlled diffusion: Monte Carlo simulations

We study the coupled two-species non-equilibrium reaction-controlled diffusion model introduced by Trimper et al. [Phys. Rev. E 62, 6071 (2000)] by means of detailed Monte Carlo simulations in one and two dimensions. Particles of type A may independently hop to an adjacent lattice site provided it is occupied by at least one B particle. The B particle species undergoes diffusion-limited reactions. In an active state with nonzero, essentially homogeneous B particle saturation density, the A species displays normal diffusion. In an inactive, absorbing phase with exponentially decaying B density, the A particles become localized. In situations with algebraic decay rho_B(t) ~ t^{-alpha_B}, as occuring either at a non-equilibrium continuous phase transition separating active and absorbing states, or in a power-law inactive phase, the A particles propagate subdiffusively with mean-square displacement ~ t^{1-alpha_A}. We find that within the accuracy of our simulation data, \alpha_A = \alpha_B as predicted by a simple mean-field approach. This remains true even in the presence of strong spatio-temporal fluctuations of the B density. However, in contrast with the mean-field results, our data yield a distinctly non-Gaussian A particle displacement distribution n_A(x,t) that obeys dynamic scaling and looks remarkably similar for the different processes investigated here. Fluctuations of effective diffusion rates cause a marked enhancement of n_A(x,t) at low displacements |x|, indicating a considerable fraction of practically localized A particles, as well as at large traversed distances.Comment: Revtex, 19 pages, 27 eps figures include

Comparative Effects of Datura stramonium Leaf and Seed Extracts on Membrane Stabilization and Platelet Aggregation In-vitro

Despite the progress in developing new therapies, inflammatory diseases remain one of the major causes of mortality. In this study, anti-inflammatory activity of the aqueous extracts of Datura stramonium leaves and seeds were evaluated. Heat and hypotonicity-induced haemolysis of human red blood cells (HRBCs) were used to determine the effect of the extracts on membrane stabilization, and the effect of the extracts on platelet aggregation was determined using calcium chloride (CaCl2)-induced platelet aggregation. The concentrations of the extracts used were 0.1, 0.2, 0.4, 0.6 and 0.8 mg/ml. Indomethacin (0.4 mg/ml) was used as the standard drug. The leaf extract significantly (p &lt; 0.05) inhibited heat-induced haemolysis by 44.47% and 52.89% at 0.2 and 0.1 mg/ml respectively compared to the seed extract. On the other hand, the seed extract significantly (p &lt; 0.05) inhibited heat-induced haemolysis by 29.5%, 44.88% and 50.01% at 0.4, 0.6 and 0.8 mg/ml respectively compared to the leaf extract. Effect of the leaf extract on hypotonicity-induced haemolysis showed that it significantly (p &lt; 0.05) inhibited haemolysis from 27.27% - 68.67% corresponding to concentrations 0.1 – 0.8 mg/ml, compared to the seed extract. The effect of the extracts on platelet aggregation showed that the leaf extract exhibited significantly (p &lt; 0.05) higher inhibition of platelet aggregation from 0 – 120 seconds, compared to the seed. Both extracts thus, have comparable effect on heat-induced haemolysis of HRBCs, though at different concentrations. The ability of the leaf extract to inhibit hypotonicity-induced haemolysis and platelet aggregation outweigh that of the seed

KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments

We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar ${}^8$B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1}$, more than one order of magnitude smaller than existing limits, and on their appearance probability$P<0.15%$(95antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field$\mu B< 2.3\times 10^{-21}$MeV 95LMA$(\Delta m^2, \tan^2\theta)$values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case,$\mu\lsim 3.9\times 10^{-12} \mu_B$(95CL) for a relatively small field$B= 50$kG. For higher values of the magnetic field we obtain:$\mu\lsim 9.0\times 10^{-13} \mu_B$for field$B= 200$kG and$\mu\lsim 2.0\times 10^{-13} \mu_B$for field$B= 1000$ kG at the same statistical significance.Comment: 13 pages, 2 figure

Epistemic policy networks in the European Union’s CBRN risk mitigation policy

This paper offers insights into an innovative and currently flagship approach of the European Union (EU) to the mitigation of chemical, biological, radiological, and nuclear (CBRN) risks. Building on its long-time experience in the CBRN field, the EU has incorporated methods familiar to the students of international security governance: it is establishing regional networks of experts and expertise. CBRN Centers of Excellence, as they are officially called, aim to contribute to the security and safety culture in different parts of Africa, the Middle East, South East Asia, and South East Europe, in the broadly construed CBRN area. These regional networks represent a modern form of security cooperation, which can be conceptualized as an epistemic policy networks approach. It offers flexibility to the participating states, which have different incentives to get involved. At the same, however, the paper identifies potential limitations and challenges of epistemic policy networks in this form

Roughening Transition in a Moving Contact Line

The dynamics of the deformations of a moving contact line on a disordered substrate is formulated, taking into account both local and hydrodynamic dissipation mechanisms. It is shown that both the coating transition in contact lines receding at relatively high velocities, and the pinning transition for slowly moving contact lines, can be understood in a unified framework as roughening transitions in the contact line. We propose a phase diagram for the system in which the phase boundaries corresponding to the coating transition and the pinning transition meet at a junction point, and suggest that for sufficiently strong disorder a receding contact line will leave a Landau--Levich film immediately after depinning. This effect may be relevant to a recent experimental observation in a liquid Helium contact line on a Cesium substrate [C. Guthmann, R. Gombrowicz, V. Repain, and E. Rolley, Phys. Rev. Lett. {\bf 80}, 2865 (1998)].Comment: 16 pages, 6 encapsulated figure