Transport of interface states in the Heisenberg chain

We demonstrate the transport of interface states in the one-dimensional ferromagnetic Heisenberg model by a time dependent magnetic field. Our analysis is based on the standard Adiabatic Theorem. This is supplemented by a numerical analysis via the recently developed time dependent DMRG method, where we calculate the adiabatic constant as a function of the strength of the magnetic field and the anisotropy of the interaction.Comment: minor revision, final version; 13 pages, 4 figure

Modeling Elasticity in Crystal Growth

A new model of crystal growth is presented that describes the phenomena on atomic length and diffusive time scales. The former incorporates elastic and plastic deformation in a natural manner, and the latter enables access to times scales much larger than conventional atomic methods. The model is shown to be consistent with the predictions of Read and Shockley for grain boundary energy, and Matthews and Blakeslee for misfit dislocations in epitaxial growth.Comment: 4 pages, 10 figure

Alveolar Echinococcosis of the Liver in an Adult with Human Immunodeficiency Virus Type-1 Infection

Abstract. : We describe a patient with human immunodeficiency virus type-1 (HIV) infection and alveolar echinococcosis (AE) with a focus on two messages. Despite being severely immunocompromised over years the patient exhibited a long-term asymptomatic course of AE. This is in clear contrast to reports describing accelerated courses of AE in immunocompromised patients. The patient had therapeutic mebendazole drug levels with only 1/10 of the normal drug dose. He was co-treated with protease inhibitors for his HIV infection. These drugs are known as strong inhibitors of cytochrome P450 3A4 (CYP3A4)-dependent metabolism. We speculate that benzimidazoles and protease inhibitors interfere at the CYP3A4-level. The first report of co-infection of HIV and accelerated AE was in a young girl with an extremely low CD4 cell count and an abrogated lymphoproliferative responsiveness to parasite antigen stimulation. Since the CD4 cell count in our patient remained in the range of 27-150 cells/µl, we speculate that there was a critical threshold of immunosupression for constraining AE. Initial treatment with albendazole for AE added to the current highly active antiretroviral treatment (HAART), and suppressive toxoplasmosis therapy became complicated by pancytopenia. After full recovery of the bone marrow, mebendazole was introduced with a new HAART and the previously prescribed toxoplasmosis maintenance therapy. Surprisingly, efficient mebendazole levels were achieved with an uncommonly low dose. These observations suggest that the benzimidazoles, albendazole and mebendazole, may interact with protease inhibitors, which are known for their strong inhibition of the CYP3A

In silico evolution of diauxic growth

The glucose effect is a well known phenomenon whereby cells, when presented with two different nutrients, show a diauxic growth pattern, i.e. an episode of exponential growth followed by a lag phase of reduced growth followed by a second phase of exponential growth. Diauxic growth is usually thought of as a an adaptation to maximise biomass production in an environment offering two or more carbon sources. While diauxic growth has been studied widely both experimentally and theoretically, the hypothesis that diauxic growth is a strategy to increase overall growth has remained an unconfirmed conjecture. Here, we present a minimal mathematical model of a bacterial nutrient uptake system and metabolism. We subject this model to artificial evolution to test under which conditions diauxic growth evolves. As a result, we find that, indeed, sequential uptake of nutrients emerges if there is competition for nutrients and the metabolism/uptake system is capacity limited. However, we also find that diauxic growth is a secondary effect of this system and that the speed-up of nutrient uptake is a much larger effect. Notably, this speed-up of nutrient uptake coincides with an overall reduction of efficiency. Our two main conclusions are: (i) Cells competing for the same nutrients evolve rapid but inefficient growth dynamics. (ii) In the deterministic models we use here no substantial lag-phase evolves. This suggests that the lag-phase is a consequence of stochastic gene expression

The atomic structure of large-angle grain boundaries Σ5\Sigma 5 and Σ13\Sigma 13 in YBa2Cu3O7−δ{\rm YBa_2Cu_3O_{7-\delta}} and their transport properties

We present the results of a computer simulation of the atomic structures of large-angle symmetrical tilt grain boundaries (GBs) $\Sigma 5$ (misorientation angles \q{36.87}{^{\circ}} and \q{53.13}{^{\circ}}), $\Sigma 13$ (misorientation angles \q{22.62}{^{\circ}} and \q{67.38}{^{\circ}}). The critical strain level $\epsilon_{crit}$ criterion (phenomenological criterion) of Chisholm and Pennycook is applied to the computer simulation data to estimate the thickness of the nonsuperconducting layer ${\rm h_n}$ enveloping the grain boundaries. The ${\rm h_n}$ is estimated also by a bond-valence-sum analysis. We propose that the phenomenological criterion is caused by the change of the bond lengths and valence of atoms in the GB structure on the atomic level. The macro- and micro- approaches become consistent if the $\epsilon_{crit}$ is greater than in earlier papers. It is predicted that the symmetrical tilt GB $\Sigma5$ \theta = \q{53.13}{^{\circ}} should demonstrate a largest critical current across the boundary.Comment: 10 pages, 2 figure

Исследование закономерностей модификации стали 12Х18Н10Т высокоинтенсивной имплантацией ионов азота

В данной работе представлены результаты по изучению формирования пучков ионов азота и их воздействие на поверхность стали 12Х18Н10Т в условиях компенсации распыления. Также было изучено формирование высокоинтенсивных пучков ионов титана. Впервые описан метод измерения глубины легированной примеси при помощи прибора CALOTEST.This paper presents the results of studying the formation of nitrogen ion beams and their effect on the surface of 12X18H10T steel under conditions of sputtering compensation. The formation of high-intensity beams of titanium ions was also studied. For the first time, a method for measuring the depth of an alloyed impurity using the CALOTEST device is described

Serodiagnosis of Echinococcus spp. Infection: Explorative Selection of Diagnostic Antigens by Peptide Microarray

Crude or purified, somatic or metabolic extracts of native antigens are routinely used for the serodiagnosis of human helminthic infections. These antigens are often cross-reactive, i.e., recognized by sera from patients infected with heterologous helminth species. To overcome limitations in antigen production, test sensitivity and specificity, chemically synthesized peptides offer a pure and standardized alternative, provided they yield acceptable operative characteristics. Ongoing genome and proteome work create new resources for the identification of antigens. Making use of the growing amount of genomic and proteomic data available in public databases, we tested a bioinformatic procedure for the selection of potentially antigenic peptides from a collection of protein sequences including conceptually translated nucleotide sequence data of Echinococcus multilocularis and E. granulosus (Plathyhelminthes, Cestoda). The in silico selection was combined with high-throughput screening of peptides on microarray and systematic validation of reactive candidates in enzyme-linked immunosorbent assay. Our study proved the applicability of this approach for selection of peptide antigens with good diagnostic characteristics. Our results suggested the pooling of several peptides to reach a high level of sensitivity required for reliable immunodiagnosis

A Pilot Study on Developing Mucosal Vaccine against Alveolar Echinococcosis (AE) Using Recombinant Tetraspanin 3: Vaccine Efficacy and Immunology

Humans and rodents become infected with E. multilocularis by oral ingesting of the eggs, which then develop into cysts in the liver and progress an endless proliferation. Untreated AE has a fatality rate of >90% in humans. Tetraspanins have been identified in Schistosoma and showed potential as the prospective vaccine candidates. In our recent study, we first identified seven tetraspanins in E. multilocularis and evaluated their protective efficacies as vaccines against AE when subcutaneously administered to BALB/c mice. Mucosal immunization of protective proteins is able to induce strong local and systemic immune responses, which might play a crucial role in protecting humans against E. multilocularis infection via the intestine, blood and liver. We focused on Em-TSP3, which achieved significant vaccine efficacy via both s.c. and i.n. routes. The adjuvanticity of nontoxic CpG OND as i.n. vaccine adjuvant was evaluated. The widespread expression of Em-TSP3 in all the developmental stages of E. multilocularis, and the strong local and systemic immune responses evoked by i.n. administration of rEm-TSP3 with CpG OND adjuvant suggest that this study might open the way for developing efficient, nontoxic human mucosal vaccines against AE

The EG95 Antigen of Echinococcus spp. Contains Positively Selected Amino Acids, which May Influence Host Specificity and Vaccine Efficacy

Echinococcosis is a worldwide zoonotic parasitic disease of humans and various herbivorous domestic animals (intermediate hosts) transmitted by the contact with wild and domestic carnivores (definitive hosts), mainly foxes and dogs. Recently, a vaccine was developed showing high levels of protection against one parasite haplotype (G1) of Echinococcus granulosus, and its potential efficacy against distinct parasite variants or species is still unclear. Interestingly, the EG95 vaccine antigen is a secreted glycosylphosphatydilinositol (GPI)-anchored protein containing a fibronectin type III domain, which is ubiquitous in modular proteins involved in cell adhesion. EG95 is highly expressed in oncospheres, the parasite life cycle stage which actively invades the intermediate hosts. After amplifying and sequencing the complete CDS of 57 Echinococcus isolates belonging to 7 distinct species, we uncovered a large amount of genetic variability, which may influence protein folding. Two positively selected sites are outside the vaccine epitopes, but are predicted to alter protein conformation. Moreover, phylogenetic analyses indicate that EG95 isoform evolution is convergent with regard to the number of beta-sheets and alpha-helices. We conclude that having a variety of EG95 isoforms is adaptive for Echinococcus parasites, in terms of their ability to invade different hosts, and we propose that a mixture of isoforms could possibly maximize vaccine efficacy