A Spin-1/2 Model for CsCuCl_3 in an External Magnetic Field

CsCuCl_3 is a ferromagnetically stacked triangular spin-1/2 antiferromagnet. We discuss models for its zero-temperature magnetization process. The models range from three antiferromagnetically coupled ferromagnetic chains to the full three-dimensional situation. The situation with spin-1/2 is treated by expansions around the Ising limit and exact diagonalization. Further, weak-coupling perturbation theory is used mainly for three coupled chains which are also investigated numerically using the density-matrix renormalization group technique. We find that already the three-chain model gives rise to the plateau-like feature at one third of the saturation magnetization which is observed in magnetization experiments on CsCuCl_3 for a magnetic field perpendicular to the crystal axis. For a magnetic field parallel to the crystal axis, a jump is observed in the experimental magnetization curve in the region of again about one third of the saturation magnetization. In contrast to earlier spinwave computations, we do not find any evidence for such a jump with the model in the appropriate parameter region.Comment: 13 pages LaTeX2e with EPJ macro package (included), 8 (e)ps figures included using psfig.sty; this is the final version to appear in Eur. Phys. J B; a few further explanations and one reference adde

Note on the occurrence of a terrestrial isopod, Hemilepistus klugii (Brandt) in Baluchistan, Pakistan

During a computer-aided search of the Crustacea collection in the Department of Invertebrate Zoology at the Smithsonian Institution (USNM), a record was found for the existence of Hemilepistus klugii (Brandt, 1833) in Pakistan

An illustrated key to Malacostraca (Crustacea) of the Northern Arabian Sea part-V: Isopoda

The northern Arabian Sea Isopod fauna is keyed out, excluding the gulfs fauna. Some terrestrial species are also included. Previous accounts and recent collections from Pakistan mainly at Karachi have turned up 7 suborders, 18 families, 76 genera and 12 1 species. There 5 are new records from Pakistan. For each species, there is an illustration and information of its reporter from the area and on its host, if parastic. The source of illustration is also given

Issues of Application Design for Social Studies

The given paper presents the relevant problem of software design for social welfare researches oriented towards the life satisfaction and other psychology studies which are important for social development. The aim of this paper is to show most important issues which can complicate application of algorithms and software for social studies e.g. testing and interviewing results analysis. It summarizes the elements of the Data Mining concepts which are vital for processing big amount of complex data characterized with weak mathematical formalization (as results of sociological studies). This article also includes description of requirements for software systems meant to be implemented in social studies and names existing software decisions in order to show their limitations. This allows us to conclude that this software implementations can be expanded and coordinated by means of new information system, created especially for solving this problem. And also includes short description of "MultiTest" web-portal designed to solve a number of problems associated with the social studies