Stability analysis of perturbed plane Couette flow

Plane Couette flow perturbed by a spanwise oriented ribbon, similar to a configuration investigated experimentally at the Centre d'Etudes de Saclay, is investigated numerically using a spectral-element code. 2D steady states are computed for the perturbed configuration; these differ from the unperturbed flows mainly by a region of counter-circulation surrounding the ribbon. The 2D steady flow loses stability to 3D eigenmodes at Re = 230, beta = 1.3 for rho = 0.086 and Re = 550, beta = 1.5 for rho = 0.043, where Re is the Reynolds number, beta is the spanwise wavenumber and rho is the half-height of the ribbon. For rho = 0.086, the bifurcation is determined to be subcritical by calculating the cubic term in the normal form equation from the timeseries of a single nonlinear simulation; steady 3D flows are found for Re as low as 200. The critical eigenmode and nonlinear 3D states contain streamwise vortices localized near the ribbon, whose streamwise extent increases with Re. All of these results agree well with experimental observations

Spiral wave drift in an electric field and scroll wave instabilities

I present the numerical computation of speed and direction of the drift of a spiral wave in an excitable medium in the presence of an electric field. In contrast to earlier results, the drift speed presents a strong variation close to the parameter value where the drift speed component along the field changes direction. Using a simple phenomenological model and results from a numerical linear stability analysis of scroll waves, I show this behavior can be attributed to a resonance of the meander modes with the translation modes of the spiral wave. Extending this phenomenological model to scroll waves also clarifies the link between the drift and long wavelength instabilities of scroll waves.Comment: Phys Rev E accepte

Parenting interventions for ADHD: a systematic literature review and meta-analysis

Objective. To evaluate the evidence base relating to the effectiveness of parent-administered behavioral interventions for ADHD

Spiral Waves in Media with Complex Excitable Dynamics

The structure of spiral waves is investigated in super-excitable reaction-diffusion systems where the local dynamics exhibits multi-looped phase space trajectories. It is shown that such systems support stable spiral waves with broken symmetry and complex temporal dynamics. The main structural features of such waves, synchronization defect lines, are demonstrated to be similar to those of spiral waves in systems with complex-oscillatory dynamics.Comment: to appear in International Journal of Bifurcation and Chao

The Kuroshio-Oyashio front as a compound vortex street

A concept presented in this paper can account for a wide variety of observed features in the Kuroshio-Oyashio front, just east of Japan. The concept, a synthetic description, consists of two von Kármán vortex streets arranged side by side; it is referred to as a compound vortex street. Von Kármán\u27s kinematic theory is generalized to include all possible vortex-street arrays...

Johnston Atoll\u27s wake

In February 1968, when the incident flow was 60 cm/sec toward the northwest, a wake resembling a von Kármán vortex street was present in the ocean downstream of Johnston Atoll (16°45\u27N, 169°31\u27W). In October 1968, when the incident flow was 15 to 20 cm/sec, no wake was detected...

Proposed Qualifications For Custodians in Certain Kansas Schools

In recent years there has been much improvement in the quality of school buildings, equipment, and supplies . Qualifications of administrators, supervisors, teachers, and almost all other employees have been advanced. Requirements and standards for custodians have begun to show a trend upward . In the last quarter of a century, janitor-engineer schools have been held to raise the standards of custodians in the proper maintenance of the school buildings and grounds . The position of the custodian in previous years has often been given to an aged person, to a cripple, to a political friend, to some incompetent person, or to anyone who could be persuaded to take it. Many of these custodians do not have a broad idea as to the duties of a custodian. As a result they do not do any more than is absolutely necessary to maintain a minimum of requirements. For several years the writer has been a principal in the elementary schools of four different communities in Western Kansas, observing the work of at least nine custodians in these buildings. He has been able to observe, in a general way, the standards of maintenance that were being met in the high schools of these communities. A need f or more competent work was displayed . From this observance and in courses in School Administration the following problem was decided upon, namely: Proposed Qualifications for Custodians in Certain Kansas Schools . Since all of the school s of the state would be difficult to cover in the limited time provided, it was suggested that a limitation be placed upon schools of certain communities . Therefore only the communities in Kansas with a population between 1000 and 10,000 were to be contacted . The Kansas Government Journal was used to check the census of these communities . One hundred thirty-two communities were selected

Evaluation of a Simple Intervention to Increase Self- Efficacy for Independent Exercise in Cardiac Rehabilitation Participants

Purpose: While benefits of exercise after a cardiac event are well documented, participation in and adherence to cardiac rehabilitation (CR) programs is often low. The purpose of this study was to test the effectiveness of a self- efficacy coaching intervention (SCI): a simple theory-based behavioral intervention to increase self-efficacy for independent exercise as well as independent exercise behavior in CR patients. It was hypothesized that persons receiving the SCI treatment (T) would have higher levels of self-efficacy for exercise and greater participation in independent exercise than participants in an attention control (C) group. Methods: People referred to a hospitalbased CR program by their physician were invited to participate in the study (N = 65). Participants were assigned to either T or C groups which had been randomly designated by class time. The SCI was administered approximately every two weeks by CR staff as a supplement to standard CR care. Patients in the T group received coaching about independent exercise, patients in the C group received coaching matched for time and technique but covering information about healthy eating. Self-efficacy for independent exercise was assessed at the beginning and end of the supervised CR program with an Exercise Self-Efficacy (ESE) scale and a Barriers Self-Efficacy (BARSE) scale. Participation in independent exercise was determined by self- report with activity logs. Outcome differences between T and C groups were analyzed through one-way ANOVA. Results: Mean change scores for the T group were larger than those seen in the C group, but differences between groups were not statistically significant (p \u3e .10). Significant difference between change scores for ESE, BARSE and independent exercise were noted when interaction effects between SCI treatment and previous exercise were considered. Conclusions: This study adds to the limited body of knowledge about theory-based interventions in cardiac rehabilitation programs and takes an important step in translating self-efficacy theory into a simple, practical application that will promote maintenance of lifestyle changes in this population

Lysimachia quadrifolia L.

https://thekeep.eiu.edu/herbarium_specimens_byname/20865/thumbnail.jp

Learning Disabilities: Assessing Stereotypes, Metastereotypes, and Stigma Consciousness

Past research has shown that students with a learning disability (LD) diagnosis face more obstacles that just their disability. The purpose of this study was twofold. The first purpose was to examine the perceived social stigma that students with a learning disability experience in college. The second purpose was to assess the existing stereotypes about students with a learning disability. Four undergraduate students with a LD and 101 students without a LD completed a questionnaire designed to assess the prevalence of stereotypes, metastereotypes, and stigmas on the college campus in regards to those with a learning disability. Students with a LD responded to what extent they felt others held stereotypes about students with a LD (metastereotypes). The specific metastereotypes and stereotypes measured were questions related to the constructs of low intelligence, process deficit, nonspecific insurmountable conditions, working the system, and compensation possible. Contrary to hypotheses, the results showed that the most endorsed stereotype construct was compensation possible, a positive stereotype that students with a LD can succeed as well as other students when provided with compensation such as extra time on tests. Overall, the results showed that some negative stereotypes about students with a LD are held, but the stereotypes are not as negative as some students with a LD believe them to be. These findings have practical implications for educating students about learning disabilities and for helping students with a learning disability feel less stigmatized