Terahertz radiation generation by beating of two spatial-Gaussian lasers

Terahertz radiation generation is proposed based on beating of two spatial-Gaussian lasers in a periodic density plasma, where a transverse component of current is realized that resonantly excites the radiation with efficiency ∼10⁻³. Importance of laser-beam-width, amplitude and periodicity of density structure is discussed for the efficient THz generation.     

Negative binomial distributions in different pseudorapidity windows in 800 GeV proton-nucleon interactions

Experimental results on multiplicity distributions for full phase space and in different pesudorapidity windows of charged secondary particles produced in proton-nucleon collisions at 800 GeV are presented and discussed. It is found that all these multiplicity distributions are well described by negative binomial distributions. We interpret our results on the basis of clan model. The bin size dependence of multiplicity distribution of charged secondary particles in proton-nucleon interactions is analysed in terms of multifractals. The values of generalised dimensions obtained from fitted distributions show a good agreement with those obtained from the data.     

Anomalous magnetic behavior of Ce1−xMxCo5(M=Zr,Hf) alloys

The compound CeCo₅ is ferromagnetically ordered with a Curie temperature (T_c) of 641 K and a moment (μ_Co) of 1.36μ_B per Co atom at 77 K. Replacement of Ce by Hf or Zr in CeCo₅ reduces the magnetic moment on cobalt but substantially increases the Curie temperature. For instance, in Ce_0.8Hf_0.2Co₅μ_Co=1.12μ_B at 77 K and T_c=846 K. These results indicate a much stronger d-d electron interaction in the ternary alloys than in CeCo₅. Ce in these systems behaves as if it is nearly quadrivalent.     

Augmented superfield approach to unique nilpotent symmetries for complex scalar fields in QED

The derivation of the exact and unique nilpotent Becchi–Rouet–Stora–Tyutin (BRST) and anti-BRST symmetries for the matter fields, present in any arbitrary interacting gauge theory, has been a long-standing problem in the framework of the superfield approach to the BRST formalism. These nilpotent symmetry transformations are deduced for the four (3+1)-dimensional (4D) complex scalar fields, coupled to the U(1) gauge field, in the framework of an augmented superfield formalism. This interacting gauge theory (i.e. QED) is considered on a six (4,2)-dimensional supermanifold parametrized by four even spacetime coordinates and a couple of odd elements of the Grassmann algebra. In addition to the horizontality condition (that is responsible for the derivation of the exact nilpotent symmetries for the gauge field and the (anti-)ghost fields), a new restriction on the supermanifold, owing its origin to the (super) covariant derivatives, has been invoked for the derivation of the exact nilpotent symmetry transformations for the matter fields. The geometrical interpretations for all the above nilpotent symmetries are discussed, too. PACS 11.15.-q, 12.20.-m, 03.70.+k     

Magnetic and magnetocaloric properties of the intermetallic compound TbNiAl

Magnetization measurements have been carried out on the intermetallic compound TbNiAl in applied fields up to 120 kOe. Temperature dependence of magnetization under zero-field-cooled and field-cooled conditions shows thermomagnetic irreversibility, which is attributed to magnetic frustration. With the increase of field, the irreversibility decreases and vanishes completely at high fields. Magnetocaloric effect has been calculated in terms of isothermal magnetic entropy change using magnetization isotherms obtained at various temperatures. The maximum entropy change is 13.8 J kg⁻¹ K⁻¹ near the ordering temperature for a field change of 50 kOe. The refrigerant capacity is found to be 494 J kg⁻¹ for the same field change and for a temperature difference of 52 K between the cold and the hot sinks.     

Consolidation of YBaCuO powders by shock loading

Superconducting oxide-copper monoliths have been fabricated by shock-wave loading using cylindrical and plane geometries. Bulk densities up to 96% T.D. have been obtained by varying detonation parameters. The superconducting properties, interface bonding and microstructure of the compacts have been evaluated.     

General relations and identities for order statistics from non-independent non-identical variables

Some recurrence relations and identities for order statistics are extended to the most general case where the random variables are assumed to be non-independent non-identically distributed. In addition, some new identities are given. The results can be used to reduce the computations considerably and also to establish some interesting combinatorial identities.     

Ultrastructural damage in photosensitized endothelial cells: dependence on hematoporphyrin delivery pathways.

The subcellular photodamage to endothelial cells in culture, revealed by transmission electron microscopy, was correlated with discrete delivery pathways of hematoporphyrin (HP). Cell detachment from the extracellular matrix, prominent water influx starting at the outer membrane and formation of blebs followed by cell death were the result of photodynamic damage induced by aqueous HP. Serum-bound HP was internalized by endocytosis and accumulated in lysosomal compartments as located after photosensitization. Obstructed lysosomal membranes, degradation of chromatin and swelling of endoplasmic reticulum were revealed in these cells. Red blood cells (RBCs), preincubated with HP, delivered low amounts of the drug to endothelial cells. The photodamage was limited to the nucleus and nucleolus. The role of photosensitizer delivery pathways in cancer cell damage is discussed.     

An approximation algorithm for a symmetric Generalized Multiple Depot, Multiple Travelling Salesman Problem

In this paper, we present an algorithm with an approximation factor of 2 for a Generalized, Multiple Depot, Multiple Travelling Salesman Problem (GMTSP) when the costs are symmetric and satisfy the triangle inequality. The algorithm requires finding a degree constrained minimum spanning tree which we compute using a Lagrangian relaxation.