Multicanonical Simulations of the Tails of the Order-Parameter Distribution of the Two-Dimensional Ising Model

We report multicanonical Monte Carlo simulations of the tails of the order-parameter distribution of the two-dimensional Ising model for fixed boundary conditions. Clear numerical evidence for "fat" stretched exponential tails is found below the critical temperature, indicating the possible presence of fat tails at the critical temperature.Comment: 4 pages, elsart3.cls (included), 5 postscript figures, author information under http://www.physik.uni-leipzig.de/index.php?id=2

Issues encountered in development of enzymelinked immunosorbent assay for use in detecting \u3ci\u3eInfluenza A virus\u3c/i\u3e subtype H5N1 exposure in swine

A potential mechanism by which highly pathogenic avian Influenza A virus subtype H5N1 could more readily infect human beings is through the infection of and adaptation in pigs. To detect the occurrence of such infection, monitoring of pig populations through serological screening would be highly desirable. In the current study, hemagglutination inhibition assays were able to detect antibodies against H5N1 developed in pigs, but because of antigenic variation between clades, the use of multiple virus strains were required. Whole recombinant virus and recombinant hemagglutinin antigen enzymelinked immunosorbent assays (ELISAs) were generated that could detect antibody against multiple H5N1 strains, but which also detected antibody against endemic swine influenza viruses. A recombinant hemagglutinin antigen-based ELISA was as effective as the whole virus antigen ELISAs in detecting antibody against the H5N1 virus strains used and eliminated nearly all of the cross-reactivity with non-H5N1 virus antibody. The current study also highlighted the difficulty in establishing a decision (cutoff) value that would effectively counterbalance nonspecific reactivity against sensitivity. The results provide important information and considerations for the development of serological screening assays for highly pathogenic avian H5N1 viruses

Swine Influenza Virus Passive Antibody Levels in Pigs from Vaccinated or Nonvaccinated Sows

Swine influenza virus passive antibody levels were measured in pigs from vaccinated vs. nonvaccinated dams. Pigs from vaccinated dams had significantly higher passive antibody titers compared with pigs from nonvaccinated dams. In pigs from nonvaccinated sows, titers \u3e20 were not detected by 8 weeks of age. In pigs from vaccinated dams, titers \u3e20 were no longer detected at 16 weeks of age. The persistence of passive antibodies may protect young pigs from SIV but also could inhibit immune responses to vaccination

Case Report—Myonecrosis in Feedlot Cattle

This report describes an outbreak of disease in a Northwestern Iowa feedlot from January to March of 2001. The cattle had been received in the feedlot in July and August, 2000. Clinical signs included severe lameness, recumbency and death. Lameness was not apparent early in the outbreak and the initial diagnosis was central nervous disease. No infectious or toxic cause could be demonstrated. Due to poor performance, approximately a third of the heifers were held back after the main group was sold. Half of these poor performing heifers displayed visible stiffness. Myonecrosis was demonstrated by significantly elevated serum creatine kinase concentrations in visibly affected cattle as compared to visibly unaffected cattle. Histological lesions were confirmed in cardiac muscle but skeletal muscle was not examined. The cattle had been fed a predominantly corn diet with a liquid supplement containing vitamin E calculated at 12.5 IU/head per day until late in the feeding period, when they were switched to a dry supplement delivering 40 IU/head per day. Serum and liver vitamin E concentrations in sampled animals were below the normal range. Common limitations in field investigations include a failure to test un-affected animals to enable comparisons between groups, testing of animals after disease onset resulting in an inability to demonstrate a temporal relationship between the cause and effect, and small sample sizes. Our case-report suffers to some extent from all these factors; however we suspect that the myonecrosis likely occurred due to Vitamin E deficiency. This presumptive diagnosis is based on the combination of knowledge of vitamin E, creatine kinase, (CK) and Aspartate Amino Transferase (AST) values in the sampled cattle, clinical signs observed, elimination of other possible etiologies and supportive statistical analyses. Investigation of unexplained debilitation in feedlot cattle, especially when accompanied by lameness, should include evaluations of serum and/or liver vitamin E concentrations, serum (AST) and (CK) concentration, muscle histology, and ration vitamin E concentration

Sequence-optimized and targeted double-stranded RNA as a therapeutic antiviral treatment against infectious myonecrosis virus in \u3ci\u3eLitopenaeus vannamei\u3c/i\u3e

Infectious myonecrosis virus (IMNV) is a significant and emerging pathogen that has a tremendous impact on the culture of the Pacific white shrimp Litopenaeus vannamei. IMNV first emerged in Brazil in 2002 and subsequently spread to Indonesia, causing large economic losses in both countries. No existing therapeutic treatments or effective interventions currently exist for IMNV. RNA interference (RNAi) is an effective technique for preventing viral disease in shrimp. Here, we describe the efficacy of a double-stranded RNA (dsRNA) applied as an antiviral therapeutic following virus challenge. The antiviral molecule is an optimized dsRNA construct that targets an IMNV sequence at the 5’ end of the genome and that showed outstanding antiviral protection previously when administered prior to infection. At least 50% survival is observed with a low dose of dsRNA administered 48 h post-infection with a lethal dose of IMNV; this degree of protection was not observed when dsRNA was administered 72 h post-infection. Additionally, administration of the dsRNA antiviral resulted in a significant reduction of the viral load in the muscle of shrimp that died from disease or survived until termination of the present study, as assessed by quantitative RT-PCR. These data indicate that this optimized RNAi antiviral molecule holds promise for use as an antiviral therapeutic against IMNV

Dynamic renormalization group study of a generalized continuum model of crystalline surfaces

We apply the Nozieres-Gallet dynamic renormalization group (RG) scheme to a continuum equilibrium model of a d-dimensional surface relaxing by linear surface tension and linear surface diffusion, and which is subject to a lattice potential favoring discrete values of the height variable. The model thus interpolates between the overdamped sine-Gordon model and a related continuum model of crystalline tensionless surfaces. The RG flow predicts the existence of an equilibrium roughening transition only for d = 2 dimensional surfaces, between a flat low-temperature phase and a rough high-temperature phase in the Edwards-Wilkinson (EW) universality class. The surface is always in the flat phase for any other substrate dimensions d > 2. For any value of d, the linear surface diffusion mechanism is an irrelevant perturbation of the linear surface tension mechanism, but may induce long crossovers within which the scaling properties of the linear molecular-beam epitaxy equation are observed, thus increasing the value of the sine-Gordon roughening temperature. This phenomenon originates in the non-linear lattice potential, and is seen to occur even in the absence of a bare surface tension term. An important consequence of this is that a crystalline tensionless surface is asymptotically described at high temperatures by the EW universality class.Comment: 22 pages, 5 figures. Accepted for publication in Physical Review

Temperature and density extrapolations in canonical ensemble Monte Carlo simulations

We show how to use the multiple histogram method to combine canonical ensemble Monte Carlo simulations made at different temperatures and densities. The method can be applied to study systems of particles with arbitrary interaction potential and to compute the thermodynamic properties over a range of temperatures and densities. The calculation of the Helmholtz free energy relative to some thermodynamic reference state enables us to study phase coexistence properties. We test the method on the Lennard-Jones fluids for which many results are available.Comment: 5 pages, 3 figure