Knowledge about AIDS among medical students in Iran

Young people are among the high risk group who are susceptible to sexually transmitted diseases. Several educational programs are scheduled to raise awareness about risky behaviours and to decrease the rate of the HIV pandemic. This cross sectional study showed that in young medical students, the level of awareness about HIV/AIDS increased during the years of academic education (not significant) and that males have a higher level of awareness than females. Higher awareness is desirable in this group due to their key role in the community

The atomic structure of ultrathin oxide films and interfaces studied by surface X-ray diffraction

X-ray diffraction (XRD) studies of the atomic structure of ultrathin oxide films and interfaces are presented, which are conducted within the framework of the Sonderforschungsbereich 762 (functionality of oxide interfaces). Knowledge of the atomic structure is at the heart of the study of functional oxides. XRD allows the investigation of complex systems frequently encountered in oxide systems (large unit cells, complex relaxation patterns, and structural and chemical disorder). Results are combined with first-principles calculations and complementary techniques providing a thorough understanding of the oxides' functionality. The structure analysis of the approximant (AP) to the 2D oxidic quasicrystal (QC) based on BaTiO3 (BTO) is discussed, the first oxide-type QC discovered. This AP is related to the Kepler tiling described 400 years ago. The LaFeO3/SrTiO3 interface is examined, which is a prototype for the formation of a 2D electron gas (2DEG). Subtle interfacial chemical roughness in combination with oxygen off-stoichiometry strongly influences the critical LaFeO3 thickness for the 2DEG formation. Finally, the analysis of the multiferroic BTO/ME(001) (ME = Fe, Pd, Pt) interface reveals that a submonolayer of impurities is the origin for the inversion of the BTO film/vacuum termination from BaO on Fe(001) to TiO2 on Pt(001)

A three-dimensional momentum-space calculation of three-body bound state in a relativistic Faddeev scheme

In this paper, we study the relativistic effects in a three-body bound state. For this purpose, the relativistic form of the Faddeev equations is solved in momentum space as a function of the Jacobi momentum vectors without using a partial wave decomposition. The inputs for the three-dimensional Faddeev integral equation are the off-shell boost two-body $t-$matrices, which are calculated directly from the boost two-body interactions by solving the Lippmann-Schwinger equation. The matrix elements of the boost interactions are obtained from the nonrelativistic interactions by solving a nonlinear integral equation using an iterative scheme. The relativistic effects on three-body binding energy are calculated for the Malfliet-Tjon potential. Our calculations show that the relativistic effects lead to a roughly 2\% reduction in the three-body binding energy. The contribution of different Faddeev components in the normalization of the relativistic three-body wave function is studied in detail. The accuracy of our numerical solutions is tested by calculation of the expectation value of the three-body mass operator, which shows an excellent agreement with the relativistic energy eigenvalue

On the motion of spinning test particles in plane gravitational waves

The Mathisson-Papapetrou-Dixon equations for a massive spinning test particle in plane gravitational waves are analysed and explicit solutions constructed in terms of solutions of certain linear ordinary differential equations. For harmonic waves this system reduces to a single equation of Mathieu-Hill type. In this case spinning particles may exhibit parametric excitation by gravitational fields. For a spinning test particle scattered by a gravitational wave pulse, the final energy-momentum of the particle may be related to the width, height, polarisation of the wave and spin orientation of the particle.Comment: 11 page

A Regularization of Burgers Equation using a Filtered Convective Velocity

This paper examines the properties of a regularization of Burgers equation in one and multiple dimensions using a filtered convective velocity, which we have dubbed as convectively filtered Burgers (CFB) equation. A physical motivation behind the filtering technique is presented. An existence and uniqueness theorem for multiple dimensions and a general class of filters is proven. Multiple invariants of motion are found for the CFB equation and are compared with those found in viscous and inviscid Burgers equation. Traveling wave solutions are found for a general class of filters and are shown to converge to weak solutions of inviscid Burgers equation with the correct wave speed. Accurate numerical simulations are conducted in 1D and 2D cases where the shock behavior, shock thickness, and kinetic energy decay are examined. Energy spectrum are also examined and are shown to be related to the smoothness of the solutions