Coherent patterns and self-induced diffraction of electrons on a thin nonlinear layer

Electron scattering on a thin layer where the potential depends self-consistently on the wave function has been studied. When the amplitude of the incident wave exceeds a certain threshold, a soliton-shaped brightening (darkening) appears on the layer causing diffraction of the wave. Thus the spontaneously formed transverse pattern can be viewed as a self-induced nonlinear quantum screen. Attractive or repulsive nonlinearities result in different phase shifts of the wave function on the screen, which give rise to quite different diffraction patterns. Among others, the nonlinearity can cause self-focusing of the incident wave into a ``beam'', splitting in two ``beams'', single or double traces with suppressed reflection or transmission, etc.Comment: RevTex, 4 pages, epsf.sty to insert figures, to appear in Phys.Rev.

Talking About Race: Comfort Levels of Racial Groups in Dialogue

The topic of race is and has always been a difficult topic for many Americans to discuss amongst members of different races. The social inequalities that exist today as a result of a discriminatory past are the basis for this communication apprehension toward race. Current literature suggests that constructive dialog is the best way to remediate social tensions based on race. This study measures the current communication comfort levels of 86 undergraduate students at a Pacific Northwest University, in regards to dialogs about race. The study reveals that the white majority is more comfortable in communicating about race and racial issues with members of the opposite race more so that minority racial group members

Universality of the Gunn effect: self-sustained oscillations mediated by solitary waves

The Gunn effect consists of time-periodic oscillations of the current flowing through an external purely resistive circuit mediated by solitary wave dynamics of the electric field on an attached appropriate semiconductor. By means of a new asymptotic analysis, it is argued that Gunn-like behavior occurs in specific classes of model equations. As an illustration, an example related to the constrained Cahn-Allen equation is analyzed.Comment: 4 pages,3 Post-Script figure

COMPARING THE RESPECTIVE EFFECTS OF THREE TYPES OF WARM-UP ON THE COUNTERMOVEMENT JUMP: AN ANALYSIS OF NON-ATHLETE COLLEGE STUDENTS

The purpose of this study was to examine and compare the respective effects of traditional, dynamic, and plyometric warm-ups on non-athlete college students’ performance of the countermovement jump (CMJ). Forty-seven male non-athlete college students were respectively allocated to three separate groups: the traditional warm-up group (TG), dynamic warm-up group (DG), and the plyometric warm-up group (PG). The DG and PG showed statistically significant improvements in push-off, force, and power (p\u3c0.001) when compared to the TG. No statistically significant differences were observed in jump height, flight time and velocity, and the effect sizes were small. The findings of this study showed that dynamic and plyometric warm-up protocols could influence CMJ performance among non-athlete college students

ANALYSIS ON THE EFFECTS OF WARM UP ON ANKLE JOINT MOTION AND STRIKE PATTERNS FOR 50M SPRINT PERFORMANCE.

The purpose of this study was to analyze the effects of ankle angles and strike pattern on 50m sprint test performance for young non-athletes. Twenty-seven non-athletes were distributed in a control group (CG) using habitual PE warm up exercises and an experimental group (EG) using basic sprint drills, and performed pre, control and post 50m sprint tests. Motion analysis data from the left leg ankle angle (LAA), right leg ankle angle (RAA) and strike pattern were obtained during landing moments in the sagittal plane using video recording. In accordance with our findings, basic sprint drill warm-ups can improve sprinting time in young girls and contribute to the strengthening of ankle muscles and joints. Motion analysis and the implementation of warm-ups with basic sprint exercises could help in the recognition of range of motion in ankle joints, and benefit sprint performance

THE INFLUENCE OF WARM-UP EXERCISES ON KNEE AND ELBOW JOINT MOTION FOR STANDING LONG JUMP PERFORMANCE

The purpose of this study was to analyse the influences of the motion angles of the knee and elbow joints on the standing long jump performance of high school students. Twenty-nine participants were assigned to either a control group to perform static and dynamic joint exercises or an experimental group to perform basic sprinting drill warm-up exercises. Both groups performed pre-, control, and post-standing long jump tests. Motion analysis of the knee and elbow joints was conducted in the sagittal plane by using video recording. Our findings support that basic sprint drill warm-up exercises can enhance the jump length in the youth. The implementation of warm-up exercises with basic sprint drills and motion analysis could be useful for determining the ranges of motion of the elbow and knee joints and improving standing long jump performance