A Wang-Landau study of the phase transitions in a flexible homopolymer

Using Wang-Landau sampling we study the characteristic behavior of a flexible homopolymer (off-lattice) for chain lengths up to N=300. The Hamiltonian consists of a Lennard-Jones potential between all monomers, and an additional FENE potential between bonded monomers. From the resultant density of states, we calculate thermodynamic properties for a wide range of temperatures, including low temperatures that are inaccessible to traditional Monte Carlo algorithms. Peaks in the specific heat and radius of gyration indicate the coil-globule and solid-liquid transitions. With a careful implementation of the algorithm, we find no evidence of a liquid-liquid transition.     

Effect of a novel combined enterosorbent "Ultrasorb" on biochemical and morphologic blood parameters

In order to estimate toxicity of a novel composition, enterosorbent "ultrasorb", its toxic properties were studied in trials on experimental animals (white rats, mice, guinea pigs). Great variety of hematolytic, biochemical and pathohistologic parameters were determined to evaluate homeostasis. As a result of toxicity trials in acute and subacute experiments as well as in embryotoxic, teratogenic and allergic tests we have concluded that enterosorbent "Ultrasorb" is absolutely harmless and can be recommended for further trials in clinics.     

Right ventricular volume characteristics in ventricular septal defect

Right and left ventricular volume characteristics were determined from biplane cineangiocardiography in 37 patients with isolated ventricular septal defects. Patients were divided into three categories as determined by the degree of left-to-right shunt: small shunt-less than 35% of pulmonary blood flow (N=9); moderate shunt-35-49% (N=8), and large shunt-greater than 50% (N=20). Right ventricular (RV) end-diastolic volume was increased above normal in 15 of 20 studies performed in patients with large left-to-right shunts and averaged 159 +/- 10% of normal (P less than 0.001). In contrast, only one of the patients in the small shunt group and only half of the patients in the moderate shunt group showed increases in RV end-diastolic volume. The increase in RV volume was proportional to the corresponding increase in left ventricular end-diastolic volume, with the right ventricle ranging from 48 to 116% of LV end-diastolic volume (average 83%). Right ventricular ejection fraction was normal in all patient groups. Right ventricular outpur was increased commensurate with the increases in the RV end-diastolic volume. These data indicate that substantial augmentation in RV end-diastolic volume does occur in patients with isolated ventricular septal defects and large left-to-right shunts. These data can be explained by the significant diastolic and "isovolumic" shunting from left ventricle to right ventricle which occurs in these patients.     

An on-line procedure for recognition of handprinted alphanumeric characters

This correspondence presents a procedure to recognize handprinted alphanumeric characters written on a graphic tablet. After preprocessing, the input character is segmented into a polygon using a simple segmentation procedure. A feature vector is formed by the parameters which describe the segments of the polygon. Classification is done in two steps, the first one based on structural information extracted from the feature vector and the second based on statistical decision rule using parameters of the segments. A recursive learning procedure is introduced in the statistical classifier. The evaluation includes the measurement of recognition rates using several statistical classifiers, the validity test on the hypothesis concerning the distribution of feature vectors and the possibility of further simplification using principal axis analysis. Databases were created and used for the evaluation.     

Cracking selectivity of a delaminated clay catalyst

Gas oil cracking selectivity is reported for a delaminated clay catalyst formed by the reaction of polyoxoaluminum cations with Laponite, a synthetic small particle hectorite. The C₅C₁₂ gasoline yields obtained with the delaminated clay more nearly approximate the selectivity of a commercial zeolite-promoted FCC catalyst than an amorphous aluminosilicate catalyst (AAA-alumina). In addition, the delaminated clay affords higher yields of light cycle gas oil and lower yields of slurry oil than the zeolite-promoted catalyst. This latter property is found also for clays which are pillared by polyoxoaluminum cations. The zeolite-like cracking properties and similarities to conventional pillared clays-suggest that some two-dimensional zeolitic character is retained by the delaminated clay, despite the absence of discrete 001 X-ray reflections and the presence of an appreciable macroporous component. The zeolite-like cracking selectivity, as well as the amorphous oxide-like macroporosity, is consistent with a previously proposed house-of-cards structure for the delaminated clay.     

The occurrence of ambient temperature-regulated adhesins, curli, and the temperature-sensitive hemagglutinin tsh among avian Escherichia coli

Escherichia coli establishes a secondary respiratory tract infection in birds following inhalation of contaminated dust and litter particles. Escherichia coli express adhesins under conditions reflective of the ambient temperatures present in poultry houses. These microbial adhesins allow E. coli to attach to cell types that it initially encounters in the respiratory tract. Ambient temperature-regulated adhesins represent a new class of bacterial hemagglutinins that include pili and the thin, aggregative, flexible filaments known as "curli." This study examines the occurrence of the ambient temperature-regulated adhesins, curli (crl, csgA), and an avian-specific, temperature-sensitive hemagglutinin, tsh, among avian and mammalian E. coli isolates. The avian hemagglutinin gene tsh was present in approximately 46% of clinical avian E. coli isolates. This gene was not detected among commensal E. coli isolated from healthy broiler chickens. Unlike tsh, curli genes were ubiquitous among E. coli. However, curli were observed in only half of the avian E. coli examined by electron microscopy. Curli were not present among several nonavian E. coli positive for crl and csgA. Approximately 25% of avian E. coli isolates agglutinated chicken erythrocytes when bacteria were grown at room temperature. Hemagglutination was not specific to E. coli isolated from poultry. Presence of either tsh or curli genes was not indicative of an isolate's ability to agglutinate chicken red blood cells. No discernible structures were observed mediating attachment of the bacteria to chicken red blood cells. An additional avian-specific hemagglutinin appears to be present among avian E. coli.     

Current induced resistive state in cylindrical superconducting films. I. Critical currents measurements

We present measurements of critical currents and critical magnetic fields in cylindrical indium films. The most interesting result is that the ratio of the experimental critical current I_c1 to Silsbee's critical value I_c0 practically does not depend on temperature. This ratio was strongly dependent on the film thickness changing from I_c1 0.18I_co for the film thickness d = 0.3m to I_c1 1.3I_co for d = 5.5m. These results cannot be explained in the framework of the existing theoretical models.On leave from Kapitza Institute for Physical Problems, 117334 Moscow, Russia.     

Making physics education more relevant and accessible via computation and eTextBooks

Various aspects of computational physics education are discussed, including the need for it, its content and various efforts at providing it. Also described is a new eTextBook that incorporates video lecture modules, source and executeable codes, multimedia enhancements and extensive linkages. The first draft is in pdf and can be “read” with a variety of devices.     

Wringing the perceptual rags: Reply to IJzerman and Koole (2011).

We Landau, Meier, & Keefer (2010) reviewed a growing body of research demonstrating metaphors' far-reaching influence on social information processing. In their commentary, IJzerman and Koole (2011) claimed that we devoted insufficient attention to the origin of metaphors, and they reviewed research showing that bodily, social, and cultural experiences constrain metaphor development. Given the focus of our article and the tone of our admittedly cursory treatment of metaphors' origins, we view IJzerman and Koole's commentary less as a critique and more as a valuable extension of our analysis. We elaborate on this extension and address three related issues raised in the comment: metaphors and representational format, the explanatory value of a metaphor-enriched perspective over the embodied cognition perspective, and the direction of metaphoric mappings between concrete and abstract concepts. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Recent developments in the preparation of nano-gold composite coatings

New possibilities in the design of gold-containing electrochemical coating systems for electronic applications are given by the incorporation of gold-nanoparticles in metal-matrix-systems. The major problem for the application of nanoparticles is the strong agglomeration of the particles in the electrolyte solutions, preventing the incorporation of nanoscaled dispersants.