Allowance for thermodynamic non-ideality in the characterization of protein self-association by frontal exclusion chromatography: hemoglobin revisited

This investigation re-examines theoretical aspects of the allowance for effects of thermodynamic non-ideality on the characterization of protein self-association by frontal exclusion chromatography, and thereby provides methods of analysis with greater thermodynamic rigor than those used previously. Their application is illustrated by reappraisal of published exclusion chromatography data for hemoglobin on the controlled-pore-glass matrix CPG-120. The equilibrium constant of 100/M that is obtained for dimerization of the (02 species by this means is also deduced from re-examination of published studies of concentrated hemoglobin solutions by osmotic pressure and sedimentation equilibrium methods. (C) 2003 Elsevier Science B.V. All rights reserved.

Kinetic parameters associated with self-heating of New Zealand coals under adiabatic conditions

Adiabatic self-heating tests were carried out on five New Zealand coal samples ranging in rank from lignite to high-volatile bituminous. Kinetic parameters of oxidation were obtained front the self-heating curves assuming Arrhenius behaviour. The activation energy E (kJ mol(-1)) and the pre-exponential factor A (s(-1)) were determined in the temperature range of 70-140 degreesC. The activation energy exhibited a definite rank relationship with a minimum E of 55 kJ mol(-1) occurring at a Suggate rank of similar to6.2 corresponding to subbituminous C. Either side of this rank there was a noticeable increase in the activation energy indicating lower reactivity of the coal. A similar rank trend was also observed in the R-70 self-heating rate index values that were taken from the initial portion of the self-heating curve front 40 to 70 degreesC. From these results it is clear that the adiabatic method is capable of providing reliable kinetic parameters of coal oxidation.

Perceived stress as a predictor of the self-reported new diagnosis of symptomatic CHD in older women

This article describes one aspect of a prospective cohort study of 10,432 women aged between 70 and 75 years. After a 3-year period, 503 women self-reported a new diagnosis by a doctor of angina or myocardial infarction (symptomatic coronary heart disease [CHD]). Time one psychosocial variables (Duke Social Support Index, time pressure, Perceived Stress Scale, Mental Health Index, having a partner, educational attainment, and location of residence) were analyzed using univariate binary logistic regression for their ability to predict subsequent symptomatic CHD. Of these variables, the Duke Social Support Index, Perceived Stress Scale and the Mental Health Index were found to be significant predictors of symptomatic CHID diagnosis. Only the Perceived Stress Scale, however, proved to be a significant independent predictor. After controlling for time one nonpsychosocial variables, as well as the frequency of family doctor visits, perceived stress remained a significant predictor of the new diagnosis of symptomatic CHD in this cohort of older women over a 3-year period.

Pseudo-randomness of round-off errors in discretized linear maps on the plane

We analyze the sequences of round-off errors of the orbits of a discretized planar rotation, from a probabilistic angle. It was shown [Bosio & Vivaldi, 2000] that for a dense set of parameters, the discretized map can be embedded into an expanding p-adic dynamical system, which serves as a source of deterministic randomness. For each parameter value, these systems can generate infinitely many distinct pseudo-random sequences over a finite alphabet, whose average period is conjectured to grow exponentially with the bit-length of the initial condition (the seed). We study some properties of these symbolic sequences, deriving a central limit theorem for the deviations between round-off and exact orbits, and obtain bounds concerning repetitions of words. We also explore some asymptotic problems computationally, verifying, among other things, that the occurrence of words of a given length is consistent with that of an abstract Bernoulli sequence.

Radial Distortion Self-Calibration

In cameras with radial distortion, straight lines in space are in general mapped to curves in the image. Although epipolar geometry also gets distorted, there is a set of special epipolar lines that remain straight, namely those that go through the distortion center. By finding these straight epipolar lines in camera pairs we can obtain constraints on the distortion center(s) without any calibration object or plumbline assumptions in the scene. Although this holds for all radial distortion models we conceptually prove this idea using the division distortion model and the radial fundamental matrix which allow for a very simple closed form solution of the distortion center from two views (same distortion) or three views (different distortions). The non-iterative nature of our approach makes it immune to local minima and allows finding the distortion center also for cropped images or those where no good prior exists. Besides this, we give comprehensive relations between different undistortion models and discuss advantages and drawbacks.

Agronomic performance of 27 cocoa progenies and plant selection based on productivity, self-compatibility and disease resistance

The objective of the present work was to evaluate 27 progenies of cocoa crosses considering the agronomic traits and select F1 plants within superior crosses. The experiment was installed in March 2005, in the Experimental Station Joaquim Bahiana (ESJOB), in Itajuipe, Bahia. The area of the experiment is of approximately 3 ha, with a total of 3240 plants. Thirteen evaluations of vegetative brooms, five of cushion brooms and 15 of number of pods per plant were accomplished. Thirty pollinations were made for each selected plant to test for self-compatibility. The production, based on the number of pods per plant, and resistance to witches´ broom indicated CEPEC 94 x CCN 10, RB 39 x CCN 51 and CCN 10 x VB 1151 as superior progenies. All selections tested were self-compatible. The analyses of progenies and individual tree data, associated to visual field observations, allowed the selection of 17 plants which were included in a network of regional tests to determine the phenotypic stability.

Pagamento de proventos versus preços deações maduras e em expansão segundo Kohonen Maps

Este estudo investiga se a política de distribuição de resultados seria capaz de alterar os preços das ações de uma empresa. O objetivo deste trabalho é discutir os impactos do pagamento de proventos sobre os preços das ações, na data ex direito, de empresas maduras e de empresas em expansão, considerando-se ainda o efeito da classe da ação (ordinária ou preferencial) sobre os resultados. Para tal, adotou-se a metodologia de dados em painel, segmentando a amostra a partir dos Mapas Auto-organizáveis de Kohonen. Os resultados revelam que a estratégia de curto prazo de comprar ações na última data com, vender na primeira data ex e embolsar os dividendos é capaz de gerar perdas de capital que superam em até quatro vezes o ganho líquido decorrente do provento embolsado.

Analysis of mediation and reciprocal effects of changes in weight, self-esteem, and exercise in a behavioral weight loss treatment

Improving the treatment of obesity remains a critical challenge. Several health behaviour change models, often based on a social-cognitive framework, have been used to design weight management interventions (Baranowski et al., 2003). However, most interventions have only produced modest weight reductions (Wadden et al., 2002) and socialcognitive variables have shown limited power to predict weight outcomes (Palmeira et al., 2007). Other predictors, and possibl alte nati e e planatory models, are needed to better understand the mechanisms by which weight loss and other obesity treatment-outcomes are brought about (Baranowski, 2006). Self-esteem is one of these possible mechanisms, because is commonly reported to change during the treatment, although these changes are not necessarily associated with weight loss (Blaine et al., 2007; Maciejewski et al., 2005). This possibility should be more evident if the program integrates regular exercise, as it promotes improvements in subjective well-being (Biddle & Mutrie, 2001), with possible influences on long-term behavioral adherence (e.g. diet, exercise). Following the reciprocal effects model tenets (Marsh & Craven, 2006), we expect that the influences between changes in weight, selfesteem and exercise to be reciprocal and might present one of the mechanisms by which obesity treatments can be improved.

Self-interacting scalar field cosmologies: unified exact solutions and symmetries

We investigate a mechanism that generates exact solutions of scalar field cosmologies in a unified way. The procedure investigated here permits to recover almost all known solutions, and allows one to derive new solutions as well. In particular, we derive and discuss one novel solution defined in terms of the Lambert function. The solutions are organised in a classification which depends on the choice of a generating function which we have denoted by x(phi) that reflects the underlying thermodynamics of the model. We also analyse and discuss the existence of form-invariance dualities between solutions. A general way of defining the latter in an appropriate fashion for scalar fields is put forward.

Equilibrium self-assembly of colloids with distinct interaction sites: Thermodynamics, percolation, and cluster distribution functions

We calculate the equilibrium thermodynamic properties, percolation threshold, and cluster distribution functions for a model of associating colloids, which consists of hard spherical particles having on their surfaces three short-ranged attractive sites (sticky spots) of two different types, A and B. The thermodynamic properties are calculated using Wertheim's perturbation theory of associating fluids. This also allows us to find the onset of self-assembly, which can be quantified by the maxima of the specific heat at constant volume. The percolation threshold is derived, under the no-loop assumption, for the correlated bond model: In all cases it is two percolated phases that become identical at a critical point, when one exists. Finally, the cluster size distributions are calculated by mapping the model onto an effective model, characterized by a-state-dependent-functionality (f) over bar and unique bonding probability (p) over bar. The mapping is based on the asymptotic limit of the cluster distributions functions of the generic model and the effective parameters are defined through the requirement that the equilibrium cluster distributions of the true and effective models have the same number-averaged and weight-averaged sizes at all densities and temperatures. We also study the model numerically in the case where BB interactions are missing. In this limit, AB bonds either provide branching between A-chains (Y-junctions) if epsilon(AB)/epsilon(AA) is small, or drive the formation of a hyperbranched polymer if epsilon(AB)/epsilon(AA) is large. We find that the theoretical predictions describe quite accurately the numerical data, especially in the region where Y-junctions are present. There is fairly good agreement between theoretical and numerical results both for the thermodynamic (number of bonds and phase coexistence) and the connectivity properties of the model (cluster size distributions and percolation locus).