Spin-spin relaxation times in myocardial hypertrophy induced by endocrine agents in rat

Magnetic resonance techniques afford a significant advantage for noninvasive diagnosis of cardiovascular pathology. The purpose of our present study was to assay the proton nuclear magnetic resonance (¹H-NMR) sensitivity in the differential diagnosis of certain endocrine cardiovascular complications. In this context, we investigated the water state and content in the hypertrophied myocardium. Male and female Wistar rats were treated with different hormones (hydrocortisone acetate, testosterone, estradiol, thyroid hormones) in combination with isoproterenol (a synthetic catecholamine that induces myocardial ischemia and hypertrophy). The animals were sacrificed after 20 days of treatment and samples of integral myocardium and left ventricular myocardium were analyzed on a¹H-NMR AREMI spectrometer (0.6 T; proton resonance at 25 MHz). The estimation ofT ₂ was made by Carr-Purcell-Meiboom-Gill pulse sequence. The data were fitted to a bi-exponential curve, yielding short (T ₂₁) values forbound water and long (T ₂₂) values forfree water. In order to evaluate the myocardial hypertrophy, the following ratios were calculated: integral myocardium to body weight; left ventricle to body weight; left ventricle to integral myocardium. The first two ratios were also calculated for dried tissue, in order to estimate its contribution to myocardial hypertrophy. Our findings demonstrate that myocardial hypertrophy is associated with a decrease ofT ₂₂, as a consequence of the increase in the dried component (i.e. proteins) of the tissue, while the total tissue, while the total tissue water (H₂O_t%, measured by gravimetry) was not significantly modified. Nevertheless, it is reasonable that the increase in the protein content would be proportional with the increase in H₂O_t%. The decrease ofT ₂₁ seems to be proportional with the level of left ventricle hypertrophy in female groups. The¹H-NMR measurements were much sensitive for the differential diagnosis of myocardial hypertrophy in the case of left ventricle.     

Experimental evidence showing that stochastic subspace identification methods may fail

It is known that certain popular stochastic subspace identification methods may fail for theoretical reasons related to positive realness. In fact, these algorithms are implicitly based on the assumption that the positive and algebraic degrees of a certain estimated covariance sequence coincide. In this paper, we describe how to generate data with the property that this condition is not satisfied. Using these data we show through simulations that several subspace identification algorithms exhibit massive failure.     

Impact of unknown covariance structures in semiparametric models for longitudinal data: An application to Wisconsin diabetes data

Semiparametric models are becoming increasingly attractive for longitudinal data analysis. Often there is lack of knowledge of the covariance structure of the response variable. Although it is still possible to obtain consistent estimators for both parametric and nonparametric components of a semipatrametric model by assuming an identity structure for the covariance matrix, the resulting estimators may not be efficient. We conducted extensive simulation studies to investigate the impact of an unknown covariance structure on estimators in semiparametric models for longitudinal data. In some situations the loss of efficiency could be substantial. A two-step estimator is thus proposed to improve the efficiency. Our study was motivated by a population based data analysis to examine the temporal relationship between systolic blood pressure and urinary albumin excretion.     

A new method for the treatment of sperm samples for ultrastructural study based on the use of animal tissues as biological containers

The study of the ultrastructure of spematozoa by means of transmission electron microscopy often presents with problems of interpretation according to the method employed, depending on whether samples are either centrifuged previously to the fixation or immersed in viscous gels. The major problems of interpretation are: changes in the location of vesicles originated during the maturation process and modifications in the adsorption of seminal plasma proteins to the sperm membrane surface. The aim of our study is to communicate an original new method for the treatment of spermatozoa for ultrastructural study. Our method is based on the use of animal tissues as biological containers, inside which the spermatic suspensions are included. We developed this method using fresh sperm samples taken from mature Rasa aragonesa rams. As biological container, we used 2.5-cm long segments of the intestine of 1-week-old chickens (Gallus gallus) (diameter around 4 mm). To avoid any influence of digestive enzymes of the mucosa on the sperm surface, we put each intestine fragment inside out by means of microdissection forceps under bifocal optical microscope and cold light. One of the edges was tied with thin suture silk. The sperm suspension was injected in the optimal experimental condition and amount. Finally, the still open edge of the intestine segment was tied with silk in the same way as the other segment edge. By using this technique, we can perform a suitable morphological study at an ultrastructural level. In addition, the functional relationship of the ultrastructural components of the target cells is correctly preserved.     

Evaluating the CMM Level 3 KPA of Intergroup Coordination: A theory-based approach

This paper examines the Intergroup Coordination key process area (KPA) for theoretical significance and measurability. The Software Engineering Institute (SEI) has developed a framework called the Capability Maturity Model (CMM) which enables organizations to measure their “maturity” in doing software engineering. The CMM is not theoretically derived. It is, however, a result of years of anecdotal evidence collected from practitioners. This paper compares the Intergroup Coordination KPA to the body of literature on coordination and measures it using theoretically derived determinants. These determinants are then evaluated for possible relationships to productivity factors that indicate business process support. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sulfonated copolymers of acrylamide synthesized by plasma-initiated copolymerization in order to obtain polymers for enhanced oil recovery

Summary High molecular weight acrylamide (AAM, M1)-co-2-acrylamido-2-methyl propane sulfonic acid (AAMPS, M2) copolymers were obtained by plasma-initiated copolymerization in water solutions. The reactivity ratios, determined by Kelen-Tudos method, were shown to be r₁=1.04 and r₂=0.41. Some microstructural aspects of the obtained copolymers are presented. In order to test a special use (mobility control in polymer flooding technology), the rheological and thermal behavior were investigated.     

Use of Genetic Algorithm in Optimization of Irrigation Pumping Stations

Energy costs constitute the largest expenditure for nearly all water utilities worldwide and can consume up to 65% of a water utility’s annual operating budget. One of the greatest potential areas for energy cost savings is in the scheduling of pump operations. This paper presents a new management model, WAPIRRA Scheduler, for the optimal design and operation of water distribution systems. The model makes use of the latest advances in genetic algorithm (GA) optimization to automatically determine annually the least cost of pumping stations while satisfying target hydraulic performance requirements. Optimal design and operation refers to selecting pump type, capacity, and number of units as well as scheduling the operation of irrigation pumps that results in minimum design and operating cost for a given set of demand curves. The optimization process consists of three main steps: (1) generating randomly an initial set of pump combinations to start the optimization process for a given demand-duration curve; (2) minimizing the total annual cost, which consists of operation and maintenance costs and depreciation cost of the initial investment, by changing the set and discharge of pump sets based on the provided model; and (3) achieving the final criterion to stop the optimization process and reporting the optimized results of the model. Computational analysis is based upon one major objective function and solving it by means of a computer program that is developed following the GA approach to find the optimized solution of generated equations. Application of the model to a real-world project shows considerable savings in cost and energy.     

Implementing Constructive Intensional Negation

Although negation is an active area of research in logic programming, sound and complete implementations are still absent from actual Prolog systems. One of the most promising techniques in the literature is intensional negation (IN), which follows a transformational approach: for each predicate p in a program its negative counterpart intneg(p) is generated. However, implementations of IN have not been included in Prolog environments due, in part, to the lack of details and explicit techniques, such as the treatment of universally quantified goals. In this paper, we describe a variant of IN, which we have called constructive intensional negation (CIN). Unlike earlier proposals, CIN does not resort to a dedicated resolution strategy when dealing with universally quantified formulae, which has been instrumental in having an effective implementation. Therefore, pure SLD resolution is used, what enables the reuse of existing Prolog implementation technology. Among the contributions of this work we can mention not only a full implementation being tested for its integration in the Ciao Prolog system but also some formal results ensuring soundness and completeness with their associated proofs.

Electrochemical and geometrical characterization of iridium oxide electrodes in stainless steel substrate

A geometrical and electrochemical characterization of stainless steel electrodes electrodeposited with iridium oxide (IrO₂) is presented. There is a dramatic increase in the double layer capacitance (C) and an important decrease in the charge transfer resistance (R_ct) after electrodeposition, causing also a significant two orders of magnitude reduction of the electrode–electrolyte interface impedance (EEIZ). These phenomena may be explained by the fine-grained iridium oxide, which has a high grain boundary density and which increases the actual electrodic area. An RC model is presented, which would explain the electrical behaviour of the system.