Electron-positron pair creation in a vacuum by an electromagnetic field in 3+1 and lower dimensions

We calculate the probability of electron-positron pair creation in vacuum in 3+1 dimensions by an external electromagnetic field composed of a constant uniform electric field and a constant uniform magnetic field, both of arbitrary magnitudes and directions. The same problem is also studied in 2+1 and 1+1 dimensions in appropriate external fields and similar results are obtained.Comment: REVTeX, 10 pages, no figure, a brief note and some more references added in the proo

Changes in food cravings and eating behavior after a dietary carbohydrate restriction intervention trial

Compared to low-fat diets, low-carbohydrate (CHO) diets cause weight loss (WL) over a faster time frame; however, it is unknown how changes in food cravings and eating behavior contribute to this more rapid WL in the early phases of dieting. We hypothesized that reductions in food cravings and improved eating behaviors would be evident even after a relatively short (4-week) duration of CHO-restriction, and that these changes would be associated with WL. Adult participants

Teacher Job Satisfaction in High-Performing Systems: A Multi-Level Study of Teacher, Classroom, and School Factors Using TALIS 2013 Surveys

Teacher job satisfaction plays a key role in influencing a quality teaching workforce and student success. This article presented an analytical framework comprising teacher, classroom and school factors, and tested it by applying a three-level modeling technique with data drawn from 11 high-performing systems that participated in Teaching and Learning International Survey (TALIS) 2013. The quantitative results show that: (1) at the teacher level, higher self-efficacy is associated with higher job satisfaction; more effective professional development and collaboration are associated with higher job satisfaction; mid-career teachers tend to be the least satisfied group compared with young and old teachers. (2) at the classroom level, teaching larger classes is associated with lower satisfaction, while teaching classes with higher percentage of low achievers or low socioeconomic students is associated with lower satisfaction; (3) at the school level, student-teacher relationship is significantly positively associated with job satisfaction. The article concludes with implications for policy makers and educators across countries

Scattering of relativistic particles with Aharonov-Bohm-Coulomb interaction in two dimensions

The Aharonov-Bohm-Coulomb potentials in two dimensions may describe the interaction between two particles carrying electric charge and magnetic flux, say, Chern--Simons solitons, or so called anyons. The scattering problem for such two-body systems is extended to the relativistic case, and the scattering amplitude is obtained as a partial wave series. The electric charge and magnetic flux is ($-q$, $-\phi/Z$) for one particle and ($Zq$, $\phi$) for the other. When $(Zq^2/\hbar c)^2\ll 1$, and $q\phi/2\pi\hbar c$ takes on integer or half integer values, the partial wave series is summed up approximately to give a closed form. The results exhibit some nonperturbative features and cannot be obtained from perturbative quantum electrodynamics at the tree level.Comment: revtex, 11 pages, no figur