A generalized finite-difference time-domain quantum method for the N-body interacting Hamiltonian

The Quantum Finite-Difference Time-Domain (FDTD-Q) method is a numerical method for solving the time evolution of the Schrödinger equation. It can be applied to systems of interacting particles, allowing for realistic simulations of quantum mechanics of various experimental systems. One of the drawbacks of the method is that divergences in the numerical evolution occur rather easily in the presence of interactions, which necessitates a large number of evolution steps or imaginary time evolution. We present a generalized (GFDTD-Q) method for solving the time-dependent Schrödinger equation including interactions between the particles. The new scheme provides a more relaxed condition for stability when the finite difference approximations for spatial derivatives are employed, as compared with the original FDTD-Q scheme. We demonstrate our scheme by simulating the time evolution of a two-particle interaction Hamiltonian. Our results show that the generalized method allows for stable time evolutions, in contrast to the original FDTD-Q scheme which produces a divergent solution.     

Limit sets, zero dynamics, and internal models in the problem of nonlinear output regulation

In this paper, we lay the foundations for a nonequilibrium theory of nonlinear output regulation, giving a more general (nonequilibrium) definition of the problem, deriving necessary conditions, and, using these necessary conditions, we present a set of sufficient conditions and a design methodology for the solution of the problem in question. Our analysis leads to a nonequilibrium enhancement of the internal model principle.     

Atorvastatin: an effective lipid-modifying agent in familial hypercholesterolemia

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are the drugs of choice in heterozygous familial hypercholesterolemia (FH), which has a high risk of ischemic heart disease. An open-label study was conducted to test the efficacy and safety of atorvastatin, a new synthetic HMG-CoA reductase inhibitor in proven FH. After a 4-week placebo phase, 22 subjects were randomized to either 80 mg atorvastatin at night (n = 11) or 40 mg twice a day for 6 weeks. The two dosage groups were well matched and had no difference in lipoprotein responses. After 6 weeks, the LDL cholesterol concentration was reduced by 57%, from 8.16 +/- 1.15 to 3.53 +/- 0.99 mmol/L (P < .001). The total cholesterol concentration decreased from 9.90 +/- 1.32 to 5.43 mmol/L (P < .001). HDL cholesterol concentration increased from 1.19 +/- 0.31 to 1.49 +/- 0.43 mmol/L (P < .001). Triglyceride concentrations decreased from 1.34 +/- 0.66 to 0.88 +/- 0.36 mmol/L (P < .01). Three subjects had single, transient increases of serum transaminase of up to twice the upper limit of normal. Apolipoprotein B concentration decreased significantly by 42%. Changes in apolipoproteins AI and (a) were not statistically significant. Nondenaturing gradient gel electrophoresis revealed increases in the size of smaller LDL particles in four subjects. Plasma fibrinogen concentration increased by 44%. The drug was well tolerated. One subject withdrew for personal reasons. Atorvastatin is a powerful and safe lipid-modifying agent for LDL cholesterol; it also modifies HDL cholesterol and triglyceride concentrations, and may suffice as a single agent for many subjects with heterozygous FH.     

Enhanced maternal aggression and associated changes in neuropeptide gene expression in multiparous rats.

Although it has often been speculated that prior reproductive experience improves subsequent maternal care, few studies have examined specific changes in behavior during a 1st versus 2nd lactation. During lactation, mothers display heightened aggression toward male intruders, purportedly to protect vulnerable young. In the current study, maternal aggression was examined in primiparous and age-matched multiparous females on postpartum days 5 (PPD5) and PPD15. Expression of oxytocin, oxytocin receptor, arginine vasopressin, arginine vasopressin V1a receptors, and corticotrophin-releasing hormone mRNA was measured following aggression testing at both time points using real-time quantitative PCR in brain regions previously implicated in the regulation of maternal aggression. Multiparity significantly enhanced maternal aggression on PPD5 but not on PPD15. In addition, this increased aggression was associated with region- and gene-specific changes in mRNA expression. These findings indicate that reproductive experience enhances maternal aggression, an effect that may be mediated by region-specific alterations in neuropeptidergic activity. The adaptations observed in multiparous females provide an innate model for the study of neuroplasticity in the regulation of aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Output regulation of nonlinear systems

The problem of controlling a fixed nonlinear plant in order to have its output track (or reject) a family of reference (or disturbance) signal produced by some external generator is discussed. It is shown that, under standard assumptions, this problem is solvable if and only if a certain nonlinear partial differential equation is solvable. Once a solution of this equation is available, a feedback law which solves the problem can easily be constructed. The theory developed incorporates previously published results established for linear systems     

The Dependency Model: A Tool for Calculating System Effectiveness

The Dependency Model (DM) is a mathematically unsophisticated but useful and practical tool for measuring the effectiveness (reliability, availability, maintainability, efficiency, etc.) of a complex system. Contrary to classical models, the DM does not require arbitrarily chosen statistical distributions or expensive simulations for its application. The large computer storage and running time requirements, the need for an accurate random number generator, and the inherent stochastic inaccuracy associated with such Monte Carlo techniques are thereby avoided. However, the DM does require the user to assign relative weights to the elements of the system, and to measure the performance of the lowest level elements considered. Common models such as GEM, TIGER, and REX assume a series-parallel structure. Although this might be sensible when applied to the lowest replaceable units (LRUs) in a hardware structure, it is unreasonable to apply it to components further up in the hierarchy, or to software. Thus, redundancy is not clearly defined for software. If there is an error in the code, placing identical programs in parallel does not eliminate that error. The series-parallel logic structure allows only for each component to be up or down, with no gradation. In contrast, the DM measures the degree of failure of a component or system, in addition to the probability and method of failure that can be determined from classical models. The elementary structure and flexibility of the DM yield additional benefits.     

Effects of interpersonal group composition on the problem-solving behavior of middle managers.

Examined the effects of compatible and incompatible group composition on the problem-solving behavior of middle managers who had spent time together in work-management conferences. 22 groups (n = 10-12 per group) were administered the Fundamental Interpersonal Relationship Orientation-Behavior at the start of their conference. The Lego Man, a problem-solving exercise, was administered the 2nd day. Groups that were more compatible on the interpersonal dimensions of control and affection completed the task more rapidly than more incompatible groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)