265 research outputs found

    Model C critical dynamics of random anisotropy magnets

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    We study the relaxational critical dynamics of the three-dimensional random anisotropy magnets with the non-conserved n-component order parameter coupled to a conserved scalar density. In the random anisotropy magnets the structural disorder is present in a form of local quenched anisotropy axes of random orientation. When the anisotropy axes are randomly distributed along the edges of the n-dimensional hypercube, asymptotical dynamical critical properties coincide with those of the random-site Ising model. However structural disorder gives rise to considerable effects for non-asymptotic critical dynamics. We investigate this phenomenon by a field-theoretical renormalization group analysis in the two-loop order. We study critical slowing down and obtain quantitative estimates for the effective and asymptotic critical exponents of the order parameter and scalar density. The results predict complex scenarios for the effective critical exponent approaching an asymptotic regime.Comment: 8 figures, style files include

    Deciding Entailments in Inductive Separation Logic with Tree Automata

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    Separation Logic (SL) with inductive definitions is a natural formalism for specifying complex recursive data structures, used in compositional verification of programs manipulating such structures. The key ingredient of any automated verification procedure based on SL is the decidability of the entailment problem. In this work, we reduce the entailment problem for a non-trivial subset of SL describing trees (and beyond) to the language inclusion of tree automata (TA). Our reduction provides tight complexity bounds for the problem and shows that entailment in our fragment is EXPTIME-complete. For practical purposes, we leverage from recent advances in automata theory, such as inclusion checking for non-deterministic TA avoiding explicit determinization. We implemented our method and present promising preliminary experimental results

    Lifelong Learning as Human Ontology: A Freirean Response to Human Capital Education

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    In this article, we argue that Freire’s view of lifelong learning is a journey toward personal growth and social transformation. Rather than reducing learners to objects of economic globalization, Freire’s pedagogy considers students political participants who actively shape their vocational and social lives

    Effective and asymptotic criticality of structurally disordered magnets

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    Changes in magnetic critical behaviour of quenched structurally-disordered magnets are usually exemplified in experiments and in MC simulations by diluted systems consisting of magnetic and non-magnetic components. By our study we aim to show, that similar effects can be observed not only for diluted magnets with non-magnetic impurities, but may be implemented, e.g., by presence of two (and more) chemically different magnetic components as well. To this end, we consider a model of the structurally-disordered quenched magnet where all lattice sites are occupied by Ising-like spins of different length LL. In such random spin length Ising model the length LL of each spin is a random variable governed by the distribution function p(L)p(L). We show that this model belongs to the universality class of the site-diluted Ising model. This proves that both models are described by the same values of asymptotic critical exponents. However, their effective critical behaviour differs. As a case study we consider a quenched mixture of two different magnets, with values of elementary magnetic moments L1=1L_1=1 and L2=sL_2=s, and of concentration cc and 1c1-c, correspondingly. We apply field-theoretical renormalization group approach to analyze the renormalization group flow for different initial conditions, triggered by ss and cc, and to calculate effective critical exponents further away from the fixed points of the renormalization group transformation. We show how the effective exponents are governed by difference in properties of the magnetic components.Comment: 17 pages, 5 figures, 1 tabl

    The activity and immunoexpression of cathepsin D in rat male reproductive organs

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    Cathepsin D is a cysteine endopeptidase that belongs to the lysosomal enzyme family. The aim of the study was to evaluate the enzyme immunoexpression and activity in selected male genital organs in mature Wistar rats. The activity of cathepsin D was measured spectrophotometrically in homogenates of the testis, epididymis, seminal vesicle and prostate. Immunohistochemical staining was also performed in the ductus deferens. Enzyme activity was found in the following sequence: testis>epididymis>dorsal prostatic lobe>seminal vesicle>lateral prostatic lobe>ventral prostatic lobe. Although there were differences in enzyme activity between various organs of the male reproductive system, cathepsin D immunoreactivity was seen exclusively in the Sertoli and Leydig cells in the testis

    Critical dynamics of diluted relaxational models coupled to a conserved density (diluted model C)

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    We consider the influence of quenched disorder on the relaxational critical dynamics of a system characterized by a non-conserved order parameter coupled to the diffusive dynamics of a conserved scalar density (model C). Disorder leads to model A critical dynamics in the asymptotics, however it is the effective critical behavior which is often observed in experiments and in computer simulations and this is described by the full set of dynamical equations of diluted model C. Indeed different scenarios of effective critical behavior are predicted.Comment: 4 pages, 5 figure

    Association of maternal pancreatic function and foetal growth in rats treated with DFU, a selective cyclooxygenase-2 inhibitor

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    Constitutive (COX-1) and inducible (COX-2) cyclooxygenase isoforms have been detected in various mammalian tissues. Their activity is blocked by non-steroidal anti-inflammatory drugs that may induce various side reactions. The aim of the study was to evaluate the effects of DFU, a selective COX-2 inhibitor, on exocrine and endocrine pancreatic function and the immunoexpression of both COX isoforms in maternal and foetal rat pancreases. The compound was administered to pregnant Wistar rats once daily from the 8th to the 21st day of gestation. Glucose level and amylase activity were determined in the maternal sera. Maternal and foetal pancreases were examined histologically. Immunoexpression of COX-1 and COX-2 was also evaluated. Both biochemical parameters, as well as the histological structure of the pancreas were undisturbed in the dams and their foetuses. The maternal glucose level was found to be an important factor for foetal growth. Strong cytoplasmic COX-1 immunostaining was observed in acinar secretory cells, whereas in islets the immune reaction was weak. Endocrine cells also revealed strong cytoplasmic COX-2 staining in the maternal and foetal pancreases. Acinar cells exhibited nuclear reaction, which was strong in the foetal but weak in the maternal pancreases. No differences in COX immunoexpression were found between the DFU-exposed and the control groups in either mothers or foetuses. It should be stressed that DFU administered throughout mid and late pregnancy in rats did not change maternal or foetal pancreatic morphology or immunoexpression of either of the main COX isoforms in the organ

    Critical behavior of the random-anisotropy model in the strong-anisotropy limit

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    We investigate the nature of the critical behavior of the random-anisotropy Heisenberg model (RAM), which describes a magnetic system with random uniaxial single-site anisotropy, such as some amorphous alloys of rare earths and transition metals. In particular, we consider the strong-anisotropy limit (SRAM), in which the Hamiltonian can be rewritten as the one of an Ising spin-glass model with correlated bond disorder. We perform Monte Carlo simulations of the SRAM on simple cubic L^3 lattices, up to L=30, measuring correlation functions of the replica-replica overlap, which is the order parameter at a glass transition. The corresponding results show critical behavior and finite-size scaling. They provide evidence of a finite-temperature continuous transition with critical exponents ηo=0.24(4)\eta_o=-0.24(4) and νo=2.4(6)\nu_o=2.4(6). These results are close to the corresponding estimates that have been obtained in the usual Ising spin-glass model with uncorrelated bond disorder, suggesting that the two models belong to the same universality class. We also determine the leading correction-to-scaling exponent finding ω=1.0(4)\omega = 1.0(4).Comment: 24 pages, 13 figs, J. Stat. Mech. in pres

    Universality classes of three-dimensional mnmn-vector model

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    We study the conditions under which the critical behavior of the three-dimensional mnmn-vector model does not belong to the spherically symmetrical universality class. In the calculations we rely on the field-theoretical renormalization group approach in different regularization schemes adjusted by resummation and extended analysis of the series for renormalization-group functions which are known for the model in high orders of perturbation theory. The phase diagram of the three-dimensional mnmn-vector model is built marking out domains in the mnmn-plane where the model belongs to a given universality class.Comment: 9 pages, 1 figur

    Harmonic crossover exponents in O(n) models with the pseudo-epsilon expansion approach

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    We determine the crossover exponents associated with the traceless tensorial quadratic field, the third- and fourth-harmonic operators for O(n) vector models by re-analyzing the existing six-loop fixed dimension series with pseudo-epsilon expansion. Within this approach we obtain the most accurate theoretical estimates that are in optimum agreement with other theoretical and experimental results.Comment: 12 pages, 1 figure. Final version accepted for publicatio
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