Controllability and stabilizability of linear time-varying distributed hereditary control systems

This paper is concerned with the controllability and stabilizability problem for control systems described by a time-varyinglinear abstract differential equation with distributed delay in the state variables. An approximate controllability propertyis established, and for periodic systems, the stabilization problem is studied. Assuming that the semigroup of operatorsassociated with the uncontrolled and non delayed equation is compact, and using the characterization of the asymptoticstability in terms of the spectrum of the monodromy operator of the uncontrolled system, it is shown that the approximatecontrollability property is a sufficient condition for the existence of a periodic feedback control law that stabilizes thesystem. The result is extended to include some systems which are asymptotically periodic. Copyright © 2014 John Wiley &Sons, Ltd.

Equação de Schrödinger não linear com coeficientes modulados

Pós-graduação em Física - FEG

Determination of Tetradifon in Brazilian Green Bell Pepper by Differential Pulse Voltammetry

Tetradifon, a potentially carcinogenic and mutagenic pesticide, can contribute to environmental and human contamination when applied to green bell pepper crops. In this context, in this work, a reliable and sensitive method for determination of tetradifon in Brazilian green bell pepper samples involving a differential pulse voltammetry (DPV) technique on a glassy carbon electrode is proposed. The electrochemical behavior of tetradifon as followed by cyclic voltammetry (CV) suggests that its reduction occurs via an irreversible five-electron transfer vs. Ag vertical bar AgCl, KCl 3 M reference electrode. Very well-resolved diffusion controlled voltammetric peaks have been obtained in a supporting electrolyte solution composed of a mixture of 40% dimethylformamide (DMF), 30% methanol, and 30% NaOH 0.3 mol L-1 at -1.43, -1.57, -1.73, -1.88, and -2.05 V. The proposed DPV method has a good linear response in the 3.00 - 10.0 mu mol L-1 range, with a limit of detection (L.O.D) of 0.756 mu mol L-1 and 0.831 mu mol L-1 in the absence and in the presence of the matrix, respectively. Moreover, improved L.O.D results (0.607 mu mol L-1) have been achieved in the absence of DMF from the supporting electrolyte solution. Recovery has been evaluated in five commercial green bell pepper samples, and recovery percentages ranging from 91.0 to 109 have been obtained for tetradifon determinations. The proposed voltammetric method has also been tested for reproducibility, repeatability, and potential interferents, and the results obtained for these three analytical parameters are satisfactory for electroanalytical purposes. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.024207jes] All rights reserved.

Existence of Solutions for Abstract Non-Autonomous Neutral Differential Equations

In this paper we discuss the existence of mild and classical solutions for a class of abstract non-autonomous neutral functional differential equations. An application to partial neutral differential equations is considered.

Optimal mean-variance control for discrete-time linear systems with Markovian jumps and multiplicative noises

In this paper, we consider the stochastic optimal control problem of discrete-time linear systems subject to Markov jumps and multiplicative noises under two criteria. The first one is an unconstrained mean-variance trade-off performance criterion along the time, and the second one is a minimum variance criterion along the time with constraints on the expected output. We present explicit conditions for the existence of an optimal control strategy for the problems, generalizing previous results in the literature. We conclude the paper by presenting a numerical example of a multi-period portfolio selection problem with regime switching in which it is desired to minimize the sum of the variances of the portfolio along the time under the restriction of keeping the expected value of the portfolio greater than some minimum values specified by the investor. (C) 2011 Elsevier Ltd. All rights reserved.

Differential regulation of PGC-1α expression in rat liver and skeletal muscle in response to voluntary running

Abstract Background The beneficial actions of exercise training on lipid, glucose and energy metabolism and insulin sensitivity appear to be in part mediated by PGC-1α. Previous studies have shown that spontaneously exercised rats show at rest enhanced responsiveness to exogenous insulin, lower plasma insulin levels and increased skeletal muscle insulin sensitivity. This study was initiated to examine the functional interaction between exercise-induced modulation of skeletal muscle and liver PGC-1α protein expression, whole body insulin sensitivity, and circulating FFA levels as a measure of whole body fatty acid (lipid) metabolism. Methods Two groups of male Wistar rats (2 Mo of age, 188.82 ± 2.77 g BW) were used in this study. One group consisted of control rats placed in standard laboratory cages. Exercising rats were housed individually in cages equipped with running wheels and allowed to run at their own pace for 5 weeks. At the end of exercise training, insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG) concentrations at constant plasma insulin levels attained during the continuous infusion of glucose and insulin to each experimental group. Subsequently, soleus and plantaris muscle and liver samples were collected and quantified for PGC-1α protein expression by Western blotting. Collected blood samples were analyzed for glucose, insulin and FFA concentrations. Results Rats housed in the exercise wheel cages demonstrated almost linear increases in running activity with advancing time reaching to maximum value around 4 weeks. On an average, the rats ran a mean (Mean ± SE) of 4.102 ± 0.747 km/day and consumed significantly more food as compared to sedentary controls (P < 0.001) in order to meet their increased caloric requirement. Mean plasma insulin (P < 0.001) and FFA (P < 0.006) concentrations were lower in the exercise-trained rats as compared to sedentary controls. Mean steady state plasma insulin (SSPI) and glucose (SSPG) concentrations were not significantly different in sedentary control rats as compared to exercise-trained animals. Plantaris PGC-1α protein expression increased significantly from a 1.11 ± 0.12 in the sedentary rats to 1.74 ± 0.09 in exercising rats (P < 0.001). However, exercise had no effect on PGC-1α protein content in either soleus muscle or liver tissue. These results indicate that exercise training selectively up regulates the PGC-1α protein expression in high-oxidative fast skeletal muscle type such as plantaris muscle. Conclusion These data suggest that PGC-1α most likely plays a restricted role in exercise-mediated improvements in insulin resistance (sensitivity) and lowering of circulating FFA levels.

Differential effects of task-specific practice on performance in a simulated penalty kick under high-pressure

Objectives The current study investigated to what extent task-specific practice can help reduce the adverse effects of high-pressure on performance in a simulated penalty kick task. Based on the assumption that practice attenuates the required attentional resources, it was hypothesized that task-specific practice would enhance resilience against high-pressure. Method Participants practiced a simulated penalty kick in which they had to move a lever to the side opposite to the goalkeeper's dive. The goalkeeper moved at different times before ball-contact. Design Before and after task-specific practice, participants were tested on the same task both under low- and high-pressure conditions. Results Before practice, performance of all participants worsened under high-pressure; however, whereas one group of participants merely required more time to correctly respond to the goalkeeper movement and showed a typical logistic relation between the percentage of correct responses and the time available to respond, a second group of participants showed a linear relationship between the percentage of correct responses and the time available to respond. This implies that they tended to make systematic errors for the shortest times available. Practice eliminated the debilitating effects of high-pressure in the former group, whereas in the latter group high-pressure continued to negatively affect performance. Conclusions Task-specific practice increased resilience to high-pressure. However, the effect was a function of how participants responded initially to high-pressure, that is, prior to practice. The results are discussed within the framework of attentional control theory (ACT).

Photoproduktion neutraler Pionen am Proton mit linear polarisierten Photonen im Bereich der Schwelle

Diese Arbeit beschreibt ein Experiment zur Photoproduktionneutraler Pionen am Proton im Schwellenbereich. DurchVerwendung linear polarisierter Photonen konnte neben dentotalen und differentiellen Wirkungsquerschnitten zum erstenMal die Photonasymmetrie nahe der Schwelle gemessen werden.Besonderes Interesse galt dem aus diesen physikalischenObservablen bestimmbaren s-Wellen-Multipol E0+ sowie der erstmaligen Bestimmung aller drei p-Wellen-KombinationenP1, P2 und P3 im Bereich der Schwelle.Das Experiment wurde 1995/1996 am ElektronenbeschleunigerMAMI (Mainzer Mikrotron) der Universität Mainz durchgeführt.Durch Verwendung eines Diamanten als Bremsstrahltarget fürdie Elektronen wurden über den Prozeß der kohärentenBremsstrahlung linear polarisierte Photonen erzeugt. DieEnergie der Photonen wurde über die Messung der Energie der gestreuten Elektronen in der MainzerPhotonenmarkierungsanlage bestimmt. Der Detektor TAPS, eineAnordnung aus 504 BaF2-Modulen, war um einFlüssigwasserstofftarget aufgebaut. In den Modulen wurdendie im Target produzierten neutralen Pionen über ihrenZerfall in zwei Photonen nachgewiesen.Die totalen und differentiellen Wirkungsquerschnitte wurdenim Energiebereich zwischen der Schwelle von 144.7 MeV und168 MeV gemessen. Die erstmals gemessene Photonasymmetriefür 159.5 MeV ist positiv und hat einen Wert von+0.217+/-0.046 für einen Polarwinkel von 90 Grad. Der Multipol E0+ und die drei p-Wellen-Kombinationen wurden andie physikalischen Observablen über zwei unterschiedlicheMethoden angepaßt, die übereinstimmende Ergebnisselieferten. Die Vorhersagen der Niederenergietheoreme derchiralen Störungstheorie für P1 und P2 stimmen beiEinbeziehung der statistischen und systematischen Fehler mitden experimentellen Werten überein.

The factorization method for real elliptic problems

The Factorization Method localizes inclusions inside a body from measurements on its surface. Without a priori knowing the physical parameters inside the inclusions, the points belonging to them can be characterized using the range of an auxiliary operator. The method relies on a range characterization that relates the range of the auxiliary operator to the measurements and is only known for very particular applications. In this work we develop a general framework for the method by considering symmetric and coercive operators between abstract Hilbert spaces. We show that the important range characterization holds if the difference between the inclusions and the background medium satisfies a coerciveness condition which can immediately be translated into a condition on the coefficients of a given real elliptic problem. We demonstrate how several known applications of the Factorization Method are covered by our general results and deduce the range characterization for a new example in linear elasticity.

Factorization method and inclusions of mixed type in an inverse elliptic boundary value problem

In various imaging problems the task is to use the Cauchy data of the solutions to an elliptic boundary value problem to reconstruct the coefficients of the corresponding partial differential equation. Often the examined object has known background properties but is contaminated by inhomogeneities that cause perturbations of the coefficient functions. The factorization method of Kirsch provides a tool for locating such inclusions. In this paper, the factorization technique is studied in the framework of coercive elliptic partial differential equations of the divergence type: Earlier it has been demonstrated that the factorization algorithm can reconstruct the support of a strictly positive (or negative) definite perturbation of the leading order coefficient, or if that remains unperturbed, the support of a strictly positive (or negative) perturbation of the zeroth order coefficient. In this work we show that these two types of inhomogeneities can, in fact, be located simultaneously. Unlike in the earlier articles on the factorization method, our inclusions may have disconnected complements and we also weaken some other a priori assumptions of the method. Our theoretical findings are complemented by two-dimensional numerical experiments that are presented in the framework of the diffusion approximation of optical tomography.

On differential operators of Calabi-Yau type

This thesis is devoted to the study of Picard-Fuchs operators associated to one-parameter families of $n$-dimensional Calabi-Yau manifolds whose solutions are integrals of $(n,0)$-forms over locally constant $n$-cycles. Assuming additional conditions on these families, we describe algebraic properties of these operators which leads to the purely algebraic notion of operators of CY-type. rnMoreover, we present an explicit way to construct CY-type operators which have a linearly rigid monodromy tuple. Therefore, we first usernthe translation of the existence algorithm by N. Katz for rigid local systems to the level of tuples of matrices which was established by M. Dettweiler and S. Reiter. An appropriate translation to the level of differential operators yields families which contain operators of CY-type. rnConsidering additional operations, we are also able to construct special CY-type operators of degree four which have a non-linearly rigid monodromy tuple. This provides both previously known and new examples.

Prevalence and types of pitfall in the assessment of mitral isthmus linear conduction block

To identify and understand clinically encountered pitfalls in the assessment of transmitral conduction block using differential coronary sinus and left atrial appendage pacing techniques in patients with left mitral isthmus linear ablation.

From episodic to habitual prospective memory: ERP-evidence for a linear transition

Performing a prospective memory task repeatedly changes the nature of the task from episodic to habitual. The goal of the present study was to investigate the neural basis of this transition. In two experiments, we contrasted event-related potentials (ERPs) evoked by correct responses to prospective memory targets in the first, more episodic part of the experiment with those of the second, more habitual part of the experiment. Specifically, we tested whether the early, middle, or late ERP-components, which are thought to reflect cue detection, retrieval of the intention, and post-retrieval processes, respectively, would be changed by routinely performing the prospective memory task. The results showed a differential ERP effect in the middle time window (450 - 650 ms post-stimulus). Source localization using low resolution brain electromagnetic tomography analysis (LORETA) suggests that the transition was accompanied by an increase of activation in the posterior parietal and occipital cortex. These findings indicate that habitual prospective memory involves retrieval processes guided more strongly by parietal brain structures. In brief, the study demonstrates that episodic and habitual prospective memory tasks recruit different brain areas.

Fully Adaptive Newton--Galerkin Methods for Semilinear Elliptic Partial Differential Equations

In this paper we develop an adaptive procedure for the numerical solution of general, semilinear elliptic problems with possible singular perturbations. Our approach combines both prediction-type adaptive Newton methods and a linear adaptive finite element discretization (based on a robust a posteriori error analysis), thereby leading to a fully adaptive Newton–Galerkin scheme. Numerical experiments underline the robustness and reliability of the proposed approach for various examples

Differential effectiveness of integrated cognitive remediation therapy for schizophrenbia outpatients: The impact oft he duration of illness

Background Nowadays there is extensive evidence available showing the efficacy of cognitive remediation (CR). To date, only limited evidence is available about the impact of the duration of illness on CR effects. The Integrated Neurocognitive Therapy (INT) represents a new developed CR approach. It is a manualized group therapy targeting all 11 NIMH-MATRICS domains. Methods In an international multicenter study, 166 schizophrenia outpatients (DSM-IV-TR) were randomly assigned either to INT or to Treatment-As-Usual (TAU). 60 patients were defined as Early Course group (EC) characterized by less than 5 years of illness, 40 patients were in the Long-Term group (LT) characterized by more than 15 years of illness, and 76 patients were in the Medium-Long-Term group (MLT) characterized by an illness of 5-15 years. Treatment comprised of 15 biweekly sessions. Assessments were conducted before and after treatment and at follow up (1 year). Multivariate General Linear Models (GLM) examined our hypothesis, whether EC, LT, and MLT groups differ under INT and TAU from each other in outcome. Results First of all, the attendance rate of 65% was significantly lower and the drop out rate of 18.5% during therapy was higher in the EC group compared to the other groups. Interaction effects regarding proximal outcome showed that the duration of illness has a strong impact on neurocognitive functioning in speed of processing (F>2.4) and attention (F>2.8). But INT intervention compared to TAU only had a significant effect in more chronically ill patients of MLT and LT, but not in younger patients in EC. In social cognitive domains, only the EC group showed a significant change in attribution (hostility; F>2.5), LT and MLT groups did not. However, no differences between the 3 groups were evident in memory, problem solving, and emotion perception. Regarding more distal outcome, LT patients had more symptoms compared to EC (F>4.4). Finally, EC patients showed higher improvements in psychosocial functioning compared to LT and MLT (F=1.8). Conclusions Against common expectations, long-term, more chronically ill patients showed higher effects in basal cognitive functions compared to younger patients and patients without any active therapy (TAU). On the other hand, early-course patients had a greater potential to change in attribution, symptoms and psychosocial functioning. Consequently, more integrated therapy offers are also recommended for long-term course schizophrenia patients.