Search for anions in molecular sources: C4H- detection in L1527

We present the results of a search for the negative ion C4H- in various dark clouds, low mass star-forming regions and photon-dominated regions (PDRs). We have also searched for C6H-, C2H- and CN- in some of the sources. The millimeter-wave observations were carried out with the IRAM-30m telescope. We detect C4H-, through the J = 9-8 and J = 10-9 rotational transitions, in the low mass star-forming region L1527. We thus confirm the tentative detection of the J = 9-8 line recently reported toward this source. The [C4H-]/[C4H] ratio found is 0.011 %, which is slightly lower than the value observed in IRC +10216, 0.024 %, but above the 3 sigma upper limit we derive in TMC-1, < 0.0052 %. We have also derived an upper limit for the [C6H-]/[C6H] ratio in the Horsehead Nebula, and for various anion-to-neutral ratios in the observed sources. These results are compared with recent chemical models.Comment: 4 pages, 1 figure; accepted for A&A Letter

Ab initio determination of an extended Heisenberg Hamiltonian in CuO2 layers

Accurate ab initio calculations on embedded Cu_4O_{12} square clusters, fragments of the La_2CuO_4 lattice, confirm a value of the nearest neighbor antiferromagnetic coupling (J=124 meV) previously obtained from ab initio calculations on bicentric clusters and in good agreement with experiment. These calculations predict non negligible antiferromagnetic second-neighbor interaction (J'=6.5 meV) and four-spin cyclic exchange (K=14 meV), which may affect the thermodynamic and spectroscopic properties of these materials. The dependence of the magnetic coupling on local lattice distortions has also been investigated. Among them the best candidate to induce a spin-phonon effect seems to be the movement of the Cu atoms, changing the Cu-Cu distance, for which the variation of the nearest neighbor magnetic coupling with the Cu-O distance is {\Delta J}/{\Delta d_{Cu-O}}\sim 1700 cm^{-1} A^{-1}.Comment: 11 pages, 5 figures, submitted to Phys. Rev.

Low-Energy Structure of Heisenberg Ferrimagnetic Spin Chains

Static and dynamic structure factors of Heisenberg ferrimagnetic spin chains are numerically investigated. There exist two distinct branches of elementary excitations, which exhibit ferromagnetic and antiferromagnetic aspects. The ferromagnetic feature is smeared out with the increase of temperature, whereas the antiferromagnetic one persists up to higher temperatures. The scattering intensity is remarkably large at lower boundaries of the ferromagnetic and antiferromagnetic spectra. All these observations are consistent with the ferromagnetic-to-antiferromagnetic crossover in the thermal behavior which has recently been reported.Comment: 3 pages, 5 PS figures, to appear in J. Phys. Soc. Jpn. Vol. 67, No. 11 (1998

New beta-Pyrochlore Oxide Superconductor CsOs2O6

The discovery of a new beta-pyrochlore oxide superconductor CsOs2O6 with Tc = 3.3 K is reported. It is the third superconductor in the family of beta-pyrochlore oxides, following KOs2O6 with Tc = 9.6 K and RbOs2O6 with Tc = 6.3 K. The Tc of this series decreases with increasing the ionic radius of alkaline metal ions, imposing negative chemical pressure upon the Os pyrochlore lattice.Comment: submitted to J. Phys. Soc Jp

A possible contribution to CMB anisotropies at high l from primordial voids

We present preliminary results of an analysis into the effects of primordial voids on the cosmic microwave background (CMB). We show that an inflationary bubble model of void formation predicts excess power in the CMB angular power spectrum that peaks between 2000 < l < 3000. Therefore, voids that exist on or close to the last scattering surface at the epoch of decoupling can contribute significantly to the apparent rise in power on these scales recently detected by the Cosmic Background Imager (CBI).Comment: 5 pages, 3 figures. MNRAS accepted versio

Moodle vs Sakai. Comparison of training courses the LMS

It compares the use of distance education systems Moodle and Sakai to create training courses and their use in the educational processСравнивается использование систем дистанционного образования Moodle и Sakai для создания учебных курсов и их использования в учебном процесс

Tari Olang-olang dalam Ritual Pengobatan Suku Sakai di Kecamatan Minas, Kabupaten Siak

Dance - Olang Olang is a reflection of the identity of rural communities Sakai tribe contained in District Minas , Siak . Olang - Olang dance is a dance for the treatment of Sakai tribe . Sakai people still believe that the human disease caused by interference spirits. Treatment system to perform the ceremony in the treatment process are dance - Olang Olang . Olang - Olang dance forms in Sakai tribal life can be seen from the form of movement , musical accompaniment and property as well as clothing that can be seen from the form covers all aspects that can be captured by the five senses . Meaning contained in Olang - Olang dance in ritual treatment Sakai people in District Minas is a ritual significance , aesthetic meaning , the meaning of cultural representation and preservation of cultural significance . Dance - Olang Olang describe the spirit of Soli , which is the ancestral spirits Sakai tribe who during his lifetime was also a Bomo . Olang - Olang has meaning flying birds . Movement of Dance - Olang Olang describe symbolize communication between Bomo with Soli spirit in healing the sick