Evolution of Microstructure and Texture during Warm Rolling Of a Duplex Steel

The effect of warm rolling on the evolution of microstructure and texture in a duplex stainless steel (DSS) was investigated. For this purpose, a DSS steel was warm rolled up to 90 pct reduction in thickness at 498 K, 698 K, and 898 K (225 °C, 425 °C, and 625 °C). The microstructure with an alternate arrangement of deformed ferrite and austenite bands was observed after warm rolling; however, the microstructure after 90 pct warm rolling at 498 K and 898 K (225 °C and 625 °C) was more lamellar and uniform as compared to the rather fragmented and inhomogeneous structure observed after 90 pct warm rolling at 698 K (425 °C). The texture of ferrite in warm-rolled DSS was characterized by the presence of the RD (〈011〉//RD) and ND (〈111〉//ND) fibers. However, the texture of ferrite in DSS warm rolled at 698 K (425 °C) was distinctly different having much higher fraction of the RD-fiber components than that of the ND-fiber components. The texture and microstructural differences in ferrite in DSS warm rolled at different temperatures could be explained by the interaction of carbon atoms with dislocations. In contrast, the austenite in DSS warm rolled at different temperatures consistently showed pure metal- or copper-type deformation texture which was attributed to the increase in stacking fault energy at the warm-rolling temperatures. It was concluded that the evolution of microstructure and texture of the two constituent phases in DSS was greatly affected by the temperature of warm rolling, but not significantly by the presence of the other phas

Stellar Kinematics and Structural Properties of Virgo Cluster Dwarf Early-Type Galaxies from the SMAKCED Project. I. Kinematically Decoupled Cores and Implications for Infallen Groups in Clusters

We present evidence for kinematically decoupled cores (KDCs) in two dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC 1453, studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. These KDCs have radii of 1.8'' (0.14 kpc) and 4.2'' (0.33 kpc), respectively. Each of these KDCs is distinct from the main body of its host galaxy in two ways: (1) inverted sense of rotation; and (2) younger (and possibly more metal-rich) stellar population. The observed stellar population differences are probably associated with the KDC, although we cannot rule out the possibility of intrinsic radial gradients in the host galaxy. We describe a statistical analysis method to detect, quantify the significance of, and characterize KDCs in long-slit rotation curve data. We apply this method to the two dE galaxies presented in this paper and to five other dEs for which KDCs have been reported in the literature. Among these seven dEs, there are four significant KDC detections, two marginal KDC detections, and one dE with an unusual central kinematic anomaly that may be an asymmetric KDC.The frequency of occurence of KDCs and their properties provide important constraints on the formation history of their host galaxies. We discuss different formation scenarios for these KDCs in cluster environments and find that dwarf-dwarf wet mergers or gas accretion can explain the properties of these KDCs. Both of these mechanisms require that the progenitor had a close companion with a low relative velocity. This suggests that KDCs were formed in galaxy pairs residing in a poor group environment or in isolation whose subsequent infall into the cluster quenched star formation.Comment: 14 pages, accepted for publication in Ap

Czech Social Reform/Non-reform: Routes, Actors and Problems

In this contribution, the author first considers the characteristics of the Czechoslovak communist welfare state and its theoretical alternatives. Throughout the reform process, dependency on both corporatist and socialist regimes won out, while residualist efforts were promoted in the beginning, but were later held back. The author then considers the possible actors involved in social reforms. In this respect, when proceeding from a general to a more concrete level, thought should first be devoted to the social classes and their ideologies, and second to political parties and their leaders. The author goes on to summarise the particular problems and traps in individual sections of the Czech social system. While no objection to decent standards of social protection and health care could be raised, the poor efficiency of their achievement should evoke concern. The author concludes by reflecting on the possible specificities of Czech social reform in comparison with the other countries undergoing reform and the EU. The current lethargy of the Czech welfare system corresponds to a “frozen edifice”, just as in most Western countries. However, such stagnation is apparently acceptable to both the politicians (who mask it in reformist rhetoric) and the population (which learned to master taking advantage of the generous welfare state) and thus is basically sustainable in the long run.http://deepblue.lib.umich.edu/bitstream/2027.42/40037/3/wp651.pd

Prevalence of arterial hypertension in patients with atrial fibrillation undergoing ablation — a prospective, cohort study

Background Arterial hypertension is one of the major cofounders in the development of atrial fibrillation (AF) and hypertension is commonly found in AF patients. The aim of the study was to establish the prevalence of arterial hypertension in patients undergoing ablation, who are relatively young and healthy group of AF patients. Material and methods 266 consecutive patients admitted for AF ablation were screened for arterial hypertension. All patients had their blood pressure measured on admission by, prior to the ablation procedure by a qualified physician, according to the current guidelines. Also, medical records of patients were reviewed for the previous diagnosis of hypertension or taking hypotensive agents. Results The study group was predominantly male (65.0%; mean age 57.6 ± 10.1 years). Mean body mass index was 29.7 ± 5.0 kg/m2. Paroxysmal AF was present in 69.5% of patients. In 72.9% of patients hypertension was diagnosed previously. On admission, mean systolic and diastolic blood pressure values were 131.7 ± 16.7 and 80.7 ± 11.1 mm Hg. 123 (46.2%) patients had systolic and/or diastolic blood pressure values respectively > 140 and/or > 90 mm Hg. Patients with previously diagnosed hypertension were older (58.7 ± 8.7 vs 54.6 ± 12.7 years; p = 0.003), had higher BMI (30.3 ± 5.0 vs 28.1 ± 4.8 kg/m2; p = 0.002), and more often history of diabetes (10.8% vs 1.4%; p = 0.03) compared to non-hypertensive group. There were no differences in terms of history of dyslipidaemia, stroke, myocardial infarction or family history of cardiovascular disease. Conclusions In patients with AF undergoing ablation procedure, prevalence of diagnosed arterial hypertension is very high, much higher than in the general population. Nevertheless, majority of patients meet the criteria for adequate blood pressure control

Monte Carlo simulation of ice models

We propose a number of Monte Carlo algorithms for the simulation of ice models and compare their efficiency. One of them, a cluster algorithm for the equivalent three colour model, appears to have a dynamic exponent close to zero, making it particularly useful for simulations of critical ice models. We have performed extensive simulations using our algorithms to determine a number of critical exponents for the square ice and F models.Comment: 32 pages including 15 postscript figures, typeset in LaTeX2e using the Elsevier macro package elsart.cl

Association between vitamin D levels and arterial hypertension in women at very high cardiovascular risk

Background Vitamin D is a compound of great importance in controlling the biological functions of the body in a variety of ways. Significance of vitamin D in the pathogenesis and treatment of various diseases has been described repeatedly. One of the most discussed issues in the literature is the importance of vitamin D deficiency in the pathogenesis of hypertension. This relationship is particularly important in patients burdened with elevated cardiovascular risk, which undoubtedly represent patients with diagnosed disease of the cardiovascular system. The aim of the study was to determine the association between the occurrence of vitamin D deficiency and the prevalence of hypertension in premenopausal women at very high cardiovascular risk. Materials and methods The study included 49 women who had previously been diagnosed with cardiovascular disease. In all patients enrolled in the study serum concentrations of vitamin D were measured and the patients were classified to have vitamin D deficiency or normal vitamin D level, based on the existing criteria. The patients were also tested for the occurrence of hypertension. Medical records of all patients were reviewed for early diagnosis of hypertension, and blood pressure measurements were performed on admission to the hospital before the surgery by a qualified physician, in a manner consistent with current guidelines Results The study population was aged 47.7 ± 13.4 years. The mean body mass index was 25.2 kg/m2. Vitamin D deficiency was diagnosed in 25 (51%) patients, and hypertension was diagnosed in 30 women (61.2%). In patients with vitamin D deficiency hypertension occurred in 18 (72%) women, while in the group without vitamin D deficiency hypertension was diagnosed in 50% of cases (12 women). The observed difference between the groups was statistically significant (p = 0.049). There was no difference in the incidence of other cardiovascular risk factors between the groups, including the prevalence of dyslipidaemia or nicotine addiction. Conclusion Association of hypertension with the vitamin D deficiency has been repeatedly underlined in many scientific studies. In the present group of patients at very high cardiovascular risk, we confirmed the relationship of vitamin D deficiency with the occurrence of hypertension. Exact confirmation of this issue requires further, largescale research, but this study may suggest the importance of vitamin D supplementation in these patients.Background Vitamin D is a compound of great importance in controlling the biological functions of the body in a variety of ways. Significance of vitamin D in the pathogenesis and treatment of various diseases has been described repeatedly. One of the most discussed issues in the literature is the importance of vitamin D deficiency in the pathogenesis of hypertension. This relationship is particularly important in patients burdened with elevated cardiovascular risk, which undoubtedly represent patients with diagnosed disease of the cardiovascular system. The aim of the study was to determine the association between the occurrence of vitamin D deficiency and the prevalence of hypertension in premenopausal women at very high cardiovascular risk. Materials and methods The study included 49 women who had previously been diagnosed with cardiovascular disease. In all patients enrolled in the study serum concentrations of vitamin D were measured and the patients were classified to have vitamin D deficiency or normal vitamin D level, based on the existing criteria. The patients were also tested for the occurrence of hypertension. Medical records of all patients were reviewed for early diagnosis of hypertension, and blood pressure measurements were performed on admission to the hospital before the surgery by a qualified physician, in a manner consistent with current guidelines Results The study population was aged 47.7 ± 13.4 years. The mean body mass index was 25.2 kg/m2. Vitamin D deficiency was diagnosed in 25 (51%) patients, and hypertension was diagnosed in 30 women (61.2%). In patients with vitamin D deficiency hypertension occurred in 18 (72%) women, while in the group without vitamin D deficiency hypertension was diagnosed in 50% of cases (12 women). The observed difference between the groups was statistically significant (p = 0.049). There was no difference in the incidence of other cardiovascular risk factors between the groups, including the prevalence of dyslipidaemia or nicotine addiction. Conclusion Association of hypertension with the vitamin D deficiency has been repeatedly underlined in many scientific studies. In the present group of patients at very high cardiovascular risk, we confirmed the relationship of vitamin D deficiency with the occurrence of hypertension. Exact confirmation of this issue requires further, largescale research, but this study may suggest the importance of vitamin D supplementation in these patients

Optical Properties of faint FIRST Variable Radio Sources

A sample of 123 radio sources that exhibit significant variations at 1.4 GHz on a seven year base-line has been created using FIRST VLA B-array data from 1995 and 2002 on a strip at dec=0 near the south Galactic cap. This sample spans the range of radio flux densities from ~2 to 1000 mJy. It presents both in size and radio flux density range a unique starting point for variability studies of galaxies and quasars harboring lower luminosity Active Galactic Nuclei (AGN). We find, by comparing our variable and non-variable control samples to the Sloan Digital Sky Survey the following: 1) The quasar fraction of both the variable and non-variable samples declines as a function of declining radio flux density levels; 2) our variable sample contains a consistently higher fraction of quasars than the non-variable control sample, irrespective of radio flux; 3) the variable sources are almost twice as likely to be retrieved from the optical SDSS data than the non-variable ones; 4) based on relative numbers, we estimate that quasars are about five times more likely to harbor a variable radio source than are galaxies; and 5) there does not appear to be any significant optical color offset between the two samples, even though the suggestive trend for sources to be bluer when variable has been detected before and may be real. This leads us to conclude that both radio variability and radio flux density levels, in combination with accurate optical information, are important discriminators in the study of (radio) variability of galaxies. The latter start to dominate the source counts below about 20 mJy. In any case, variability appears to be an intrinsic property of radio sources, and is not limited to quasars. Radio variability at low flux density levels may offer a unique tool in AGN unification studies.Comment: 22 pages, 10 color figures. Accepted for publication in AJ, May issu

Quantum effects in the quasiparticle structure of the ferromagnetic Kondo lattice model

A new ``Dynamical Mean-field theory'' based approach for the Kondo lattice model with quantum spins is introduced. The inspection of exactly solvable limiting cases and several known approximation methods, namely the second-order perturbation theory, the self-consistent CPA and finally a moment-conserving decoupling of the equations of motion help in evaluating the new approach. This comprehensive investigation gives some certainty to our results: Whereas our method is somewhat limited in the investigation of the J<0-model, the results for J>0 reveal important aspects of the physics of the model: The energetically lowest states are not completely spin-polarized.A band splitting, which occurs already for relatively low interaction strengths, can be related to distinct elementary excitations, namely magnon emission (absorption) and the formation of magnetic polarons. We demonstrate the properties of the ferromagnetic Kondo lattice model in terms of spectral densities and quasiparticle densities of states.Comment: 19 pages, 4 figure

Some approximate analytical methods in the study of the self-avoiding loop model with variable bending rigidity and the critical behaviour of the strong coupling lattice Schwinger model with Wilson fermions

Some time ago Salmhofer demonstrated the equivalence of the strong coupling lattice Schwinger model with Wilson fermions to a certain 8-vertex model which can be understood as a self-avoiding loop model on the square lattice with bending rigidity $\eta = 1/2$ and monomer weight $z = (2\kappa)^{-2}$. The present paper applies two approximate analytical methods to the investigation of critical properties of the self-avoiding loop model with variable bending rigidity, discusses their validity and makes comparison with known MC results. One method is based on the independent loop approximation used in the literature for studying phase transitions in polymers, liquid helium and cosmic strings. The second method relies on the known exact solution of the self-avoiding loop model with bending rigidity $\eta = 1/\sqrt{2}$. The present investigation confirms recent findings that the strong coupling lattice Schwinger model becomes critical for $\kappa_{cr} \simeq 0.38-0.39$. The phase transition is of second order and lies in the Ising model universality class. Finally, the central charge of the strong coupling Schwinger model at criticality is discussed and predicted to be $c = 1/2$.Comment: 22 pages LaTeX, 6 Postscript figure

The square-lattice F model revisited: a loop-cluster update scaling study

The six-vertex F model on the square lattice constitutes the unique example of an exactly solved model exhibiting an infinite-order phase transition of the Kosterlitz-Thouless type. As one of the few non-trivial exactly solved models, it provides a welcome gauge for new numerical simulation methods and scaling techniques. In view of the notorious problems of clearly resolving the Kosterlitz-Thouless scenario in the two-dimensional XY model numerically, the F model in particular constitutes an instructive reference case for the simulational description of this type of phase transition. We present a loop-cluster update Monte Carlo study of the square-lattice F model, with a focus on the properties not exactly known such as the polarizability or the scaling dimensions in the critical phase. For the analysis of the simulation data, finite-size scaling is explicitly derived from the exact solution and plausible assumptions. Guided by the available exact results, the careful inclusion of correction terms in the scaling formulae allows for a reliable determination of the asymptotic behaviour.Comment: 28 pages, 11 figures, 4 tables, revised version as publishe