Non - flying mammalian fauna of Ampijoroa, Ankarafantsika National Park

There is no list of the mammalian fauna of Ampijoroa Forest Station, a dry deciduous forest within Ankarafantsika National Park. We set Sherman traps and pitfall traps and carried out transect surveys to survey the non - flying mammalian fauna of Ampijoroa. In total, 19 species of mammals were recorded, comprising 10 families. Records include three species of Tenrecidae, two species of Soricidae, one species of Muridae, three species of Nesomyidae, three species of Cheirogaleidae, one species of Lepilemuridae, two species of Lemuridae, two species of Indriidae, one species of Eupleridae, and one species of Suidae

Fe-doping-induced evolution of charge-orbital ordering in a bicritical-state manganite

Impurity effects on the stability of a ferromagnetic metallic state in a bicritical-state manganite, (La0.7Pr0.3)0.65Ca0.35MnO3, on the verge of metal-insulator transition have been investigated by substituting a variety of transition-metal atoms for Mn ones. Among them, Fe doping exhibits the exceptional ability to dramatically decrease the ferromagnetic transition temperature. Systematic studies on the magnetotransport properties and x-ray diffraction for the Fe-doped crystals have revealed that charge-orbital ordering evolves down to low temperatures, which strongly suppresses the ferromagnetic metallic state. The observed glassy magnetic and transport properties as well as diffuse phase transition can be attributed to the phase-separated state where short-range charge-orbital-ordered clusters are embedded in the ferromagnetic metallic matrix. Such a behavior in the Fe-doped manganites form a marked contrast to the Cr-doping effects on charge-orbital-ordered manganites known as impurity-induced collapse of charge-orbital ordering.Comment: 8 pages, 7 figure

Fast vectorized algorithm for the Monte Carlo Simulation of the Random Field Ising Model

An algoritm for the simulation of the 3--dimensional random field Ising model with a binary distribution of the random fields is presented. It uses multi-spin coding and simulates 64 physically different systems simultaneously. On one processor of a Cray YMP it reaches a speed of 184 Million spin updates per second. For smaller field strength we present a version of the algorithm that can perform 242 Million spin updates per second on the same machine.Comment: 13 pp., HLRZ 53/9

Strange Mesonic Transition Form Factor in the Chiral Constituent Quark Model

The form factor $g_{\rho \pi}^{(S)}(Q^{2})$ of the strange vector current transition matrix element $$ is calculated within the chiral quark model. A strange vector current of the constituent $U$- and D-quarks is induced by kaon radiative corrections and this mechanism yields the nonvanishing values of $g_{\rho\pi}^{(S)}(0)$. The numerical result at the photon point is consistent with the one given by the $\phi$-meson dominance model, but the fall-off in the $Q^{2}$-dependence is faster than the monopole form factor. Mesonic radiative corrections are also examined for the electromagnetic $\rho$-to-$\pi$ and $K^{*}$-to-$K$ transition amplitudes.Comment: LaTex 11 pages, 2 PostScript figure

Charge form factor of π\pi and KK mesons

The charge form factor of $\pi$ and $K$ mesons is evaluated adopting a relativistic constituent quark model based on the light-front formalism. The relevance of the high-momentum components of the meson wave function, for values of the momentum transfer accessible to $CEBAF$ energies, is illustrated. The predictions for the elastic form factor of $\pi$ and $K$ mesons are compared with the results of different relativistic approaches, showing that the measurements of the pion and kaon form factors planned at $CEBAF$ could provide information for discriminating among various models of the meson structure.Comment: 8 pages, latex, 4 figures available as separate .uu fil

Tight-binding parameters and exchange integrals of Ba_2Cu_3O_4Cl_2

Band structure calculations for Ba_2Cu_3O_4Cl_2 within the local density approximation (LDA) are presented. The investigated compound is similar to the antiferromagnetic parent compounds of cuprate superconductors but contains additional Cu_B atoms in the planes. Within the LDA, metallic behavior is found with two bands crossing the Fermi surface (FS). These bands are built mainly from Cu 3d_{x^2-y^2} and O 2p_{x,y} orbitals, and a corresponding tight-binding (TB) model has been parameterized. All orbitals can be subdivided in two sets corresponding to the A- and B-subsystems, respectively, the coupling between which is found to be small. To describe the experimentally observed antiferromagnetic insulating state, we propose an extended Hubbard model with the derived TB parameters and local correlation terms characteristic for cuprates. Using the derived parameter set we calculate the exchange integrals for the Cu_3O_4 plane. The results are in quite reasonable agreement with the experimental values for the isostructural compound Sr_2Cu_3O_4Cl_2.Comment: 5 pages (2 tables included), 4 ps-figure

Novel Magnetic and Thermodynamic Properties of Thiospinel Compound CuCrZrS4_{4}

We have carried out dc magnetic susceptibility, magnetization and specific heat measurements on thiospinel CuCrZrS$_{4}$. Below $T_{\rm C}^{*} =$ 58 K, dc magnetic susceptibility and magnetization data show ferromagnetic behavior with a small spontaneous magnetization 0.27 $\mu_{\rm B}/$f. u.. In dc magnetic susceptibility, large and weak irreversibilities are observed below $T_{\rm f} =$ 6 K and in the range $T_{\rm f}< T < T_{\rm C}^{*}$ respectively. We found that there is no anomaly as a peak or step in the specific heat at $T_{\rm C}^{*}$.Comment: 11 pages, 4 figure

The electron-nucleon cross section in (e,e′p)(e,e'p) reactions

We examine commonly used approaches to deal with the scattering of electrons from a bound nucleon. Several prescriptions are shown to be related by gauge transformations. Nevertheless, due to current non-conservation, they yield different results. These differences reflect the size of the uncertainty that persists in the interpretation of $(e,e'p)$ experiments.Comment: 6 pp (10 in preprint form), ReVTeX, (+ 4 figures, uuencoded

Domain growth by isothermal aging in 3d Ising and Heisenberg spin glasses

Non-equilibrium dynamics of three dimensional model spin glasses - the Ising system Fe$_{0.50}$Mn$_{0.50}$TiO$_3$ and the Heisenberg like system Ag(11 at% Mn) - has been investigated by measurements of the isothermal time decay of the low frequency ac-susceptibility after a quench from the paramagnetic to the spin glass phase. It is found that the relaxation data measured at different temperatures can be scaled according to predictions from the droplet scaling model, provided that critical fluctuations are accounted for in the analyzes.Comment: 5 pages, 3 figure