Systematic investigations of transient response of nuclear spins in the presence of polarized electrons

We electrically probed the transient response of nuclear spins in an n-GaAs channel by performing Hanle signal and spin-valve signal measurements on an all-electrical spin-injection device having a half-metallic spin source of Co2MnSi. Furthermore, we simulated the Hanle and spin-valve signals by using the time evolution of nuclear-spin polarization under the presence of polarized electron spins by taking both T-1e and T-1 into consideration, where T-1e(-1) is the polarization rate of nuclear spins through the transfer of angular momentum from polarized electron spins and T-1(-1) is the depolarization rate of nuclear spins through the interaction with the lattice. The simulation results reproduced our experimental results on all the nuclear-spin-related phenomena appearing in the Hanle and spin-valve signals at different measurement conditions, providing quantitative explanation for the transient response of nuclear spins in GaAs to a change in magnetic fields and an estimate of the time scales of T-1e and T-1. These experimental and simulated results will deepen the understanding of nuclear-spin dynamics in semiconductors

A comparison of authoritative and participative leadership styles regarding physical education teachers' efficiency

The purpose of this study is to compare the authoritative and participative leadership styles regarding physical education teachers` efficiency. To this end, 40 school principals and 40 male and female physical education teachers at secondary schools were randomly assigned to participate in the study . School principals performance assessed with Fiddler leadership style questionnaire with reliability coefficient of 0.86 by teachers.Also, teachers`performance evaluated with teacher -made questionnaire with validity coefficient of 0.87 (Cronbach Alpha) completed by the students. Data distribution was normal shown in this study using kolmogorov-smirnov test. Additionally,statistical method in terms of statistical model is parametric,while non-parametric statistics is employed for heterogeneous groups through which desired hypotheses discussed using Pearson correlation test, Spearman correlation coefficient and T –test. Results indicate that there exists a significant relationship between the leadership style of school principals and physical education teachers efficiency at 5% significance level.The results show that participative leadership style would end up with substantial efficiency of male and female education teachers, whereas authoritative leadership style has shown the lowest efficiency

On the Calabi-Yau Phase of (0,2) Models

We study the Calabi-Yau phase of a certain class of (0,2) models. These are conjectured to be equivalent to exact (0,2) superconformal field theories which have been constructed recently. Using the methods of toric geometry we discuss in a few examples the problem of resolving the singularities of such models and calculate the Euler characteristic of the corresponding gauge bundles.Comment: LaTex; 22 pages, the last part of the concluding section has been modifie

Removal of Iron (II) from Wastewater by Locally Prepared of Activated Carbon

The use of low-cost activated carbon derived from reed, an agricultured waste material, has been investigated for the removed of Fe (II) from wastewater, using batch method. The influences of the weight of adsorbent (0.2-2) g, pH of solution (1-9) and initial Fe(II) concentration (10-80) mg/l have been studied. The suitability of the activated carbon used was tested by fitting the adsorption data with Langmuir and Freundlich isotherms. The study showed that the adsorption data obtained are obey the Freundlich isotherm fitting

Determining coal directional mechanical properties using true triaxial testing facility

Knowledge of coal mechanical properties and strength is critical in modelling and understanding pillar stability, gateroads stability, gas drainage borehole integrity as well as coal responses to hydraulic fracturing stimulation. However, due to the complexity of coal structures and difficulties in obtaining decent coal specimens, measurements of coal mechanical properties have been limited to the application of traditional triaxial and UCS tests, which in turn has shown adverse influence on the design confidence and reliability in practice. In addition, coal is an anisotropic material and such conventional testing techniques are clearly not capable of directly capturing coal anisotropic features. In this work, a true tri-axial testing facility was used to quantify coal strength and its anisotropic characteristics. Eight 50 mm side cube coal blocks were prepared and three types of tests were implemented. The proposed testing procedure measured successfully the mean values of coal young’s moduli in three different x, y and z (vertical) directions as 1,025 MPa, 1,887 MPa, and 2,543 MPa, respectively, which gives the ratio of 1.00: 1.84: 2.48. The mean Poisson’s ratio is also measured as 0.098, 0.038, and 0.091 in x, y and z directions. Coal strength follows the Hoek-Brown criterion reasonably well, and the m value is found to be 23.9. These findings suggest that the implementation of true-triaxial testing techniques for coal mechanical properties can effectively capture its anisotropic characteristics, which could enhance analysis confidence for future designs

Workplace violence against nurses at Minia district hospitals

Introduction: Violence against nurses at the workplace is an alarming problem in both developed and developing countries affecting the quality of their work. The aim of this study is to assess the prevalence of external (patient initiated) and internal violence (initiated by staff members) against nurses and studying the violence-associated factors such as perpetrators, the attitude of nurses following aggression incidents, consequences, and impact on nurses and work. Methods: A cross-sectional study included 385 nurses from three different hospitals in Minia district was agreed to participate in the study. These hospitals included Health Insurance Hospital, Minia University Hospitals (Minia University Gynecological, Obstetric, and Pediatric Hospital and Minia Renal Hospital), and Minia general hospital. The well-structured questionnaire covered four main domains; sociodemographics, lifetime working experience of violence, external and internal violence and its effects on work, the perpetrators of violence, and attitude of nurses following violent incidents. Results: More than half of nurses (55.8%) were exposed to workplace violence during their working lifetime. Experiencing external violence (patient initiated) during the past year was significantly higher (57.4%) than the internal (staff initiated) type (33.5%). Verbal violence was the most common type of violence. Reporting violence incidents were done by 68.3% and 38.7% of the nurses who were exposed to external and internal violence, respectively. Conclusion: Violence against nurses working in different health-care facilities at Minia district was prevalent and has a significant impact on nurses and their work

Myocardial uptake of Tc-99m HDP in a patient with prostate carcinoma

In this case report we present an unusual appearance of myocardial uptake of Tc-99m HDP in a 59-year-old renal transplant patient who was imaged while looking for metastases from adenocarcinoma of the prostate. Subsequent investigation demonstrated no obvious cause for this appearance, such as myocardial disease or metastatic cancer. The case report, therefore, discusses the possible causes of such an appearance and reviews the literature concerning this phenomenon