Optical properties of small polarons from dynamical mean-field theory

The optical properties of polarons are studied in the framework of the Holstein model by applying the dynamical mean-field theory. This approach allows to enlighten important quantitative and qualitative deviations from the limiting treatments of small polaron theory, that should be considered when interpreting experimental data. In the antiadiabatic regime, accounting on the same footing for a finite phonon frequency and a finite electron bandwidth allows to address the evolution of the optical absorption away from the well-understood molecular limit. It is shown that the width of the multiphonon peaks in the optical spectra depends on the temperature and on the frequency in a way that contradicts the commonly accepted results, most notably in the strong coupling case. In the adiabatic regime, on the other hand, the present method allows to identify a wide range of parameters of experimental interest, where the electron bandwidth is comparable or larger than the broadening of the Franck-Condon line, leading to a strong modification of both the position and the shape of the polaronic absorption. An analytical expression is derived in the limit of vanishing broadening, which improves over the existing formulas and whose validity extends to any finite-dimensional lattice. In the same adiabatic regime, at intermediate values of the interaction strength, the optical absorption exhibits a characteristic reentrant behavior, with the emergence of sharp features upon increasing the temperature -- polaron interband transitions -- which are peculiar of the polaron crossover, and for which analytical expressions are provided.Comment: 16 pages, 6 figure

The Optical Gravitational Lensing Experiment. Catalog of stellar proper motions in the OGLE-II Galactic bulge fields

We present a proper motion (\mu) catalogue of 5,080,236 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge (GB) fields, covering a range of -11 deg. <l< 11 deg. and -6 deg. <b<3 deg., the total area close to 11 square degrees. The proper motion measurements are based on 138 - 555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes Red Clump Giants (RCGs) and Red Giants in the GB, and main sequence stars in the Galactic disc. The proper motions up to \mu = 500 mas/yr were measured with the mean accuracy of 0.8-3.5 mas/yr, depending on the brightness of a star. This catalogue may be useful for studying the kinematic of stars in the GB and the Galactic disk.Comment: 13 pages, 16 figures, MNRAS in pres

Peningkatan Kepercayaan Diri Mahasiswa melalui Pelatihan Asertivitas

This study was initiated by the observation that Brawijaya University psychology student batch 2007 and 2008 appeared passive in the teaching-learning process. It is acknowledged that an assertive training will be needed. The training is expected to be a pilot project or the initial steps for the implementation of students' soft skills.This study aims to determine the effectiveness of assertive training to enhance student confidence. Subjects of 22 psychology students will be examined through experimental repeated measure design methodSelf confidence level was measured twice pre and post the training given. Based on the t-test test results of the self confidence level rates obtained from the pre test mean of 103.68 with standard deviations of 7.17. While the post test came up with mean of 122.45 with standard deviations of 10.05. The results of the research showed that the confidence scores of students increased significantly after the training is given. This conclusion showed that assertive training was effective to improve confidence level of the students

Optimalisasi Pemanfaatan Sumber Daya Lokal Berbasis Pengolahan Pangan di Desa Mantingan, Kecamatan Jaken, Kabupaten Pati

Community empowerment needs to be realized to increase the independence of village communities. Community empowerment activities in the village of Mantingan, especially KWT Al-Ikhlas, can improve knowledge and skills related to the processing of chili and shallot agricultural products, as well as take advantage of the telang flower which is rich in benefits. The method of implementation is carried out in several activities, namely discussions with partners, trials of making chili and siwang powder, training in making chili and siwang powder, planting telang flowers, and making agricultural product brands. The community prefers to sell chilies and shallots directly to collectors even when the price of chilies and shallots drops. The community considers the telang plant to be a wild plant because they do not know the benefits of the telang flower. Making chili powder is done to overcome the price of chili which tends to fluctuate and extend the self-life of the chilies being harvested. The innovation in processing chili powder "Mak Chilli Tini" and "Siwang Mak Tini" onion paste has a large potential profit margin. The chili powder product "Mak Chilli Tini" and the onion paste "Siwang Mak Tini" have a lower selling price per gram than other products and PIRT certificates, so the optimism to legally compete with the broad market is high. Socialization about the benefits of telang flowers has made the people of Mantingan Village more familiar with telang flowers and are interested in planting them. Telang plants were distributed to 44 residents of Mantingan Village. This activity helps the people of Mantingan Village to solve 2 main problems, namely the fluctuating price of chilies and shallots in the market and the problem of marketing KWT commodities that have not been maximized. Keywords: chilies, shallots, siwang, telan

Microlensing optical depth toward the Galactic Bulge using bright sources from OGLE-II

We present a measurement of the microlensing optical depth toward the Galactic Bulge based on 4 years of the OGLE-II survey using Red Clump Giant (RCG). Using 32 events we find tau=2.55_{-0.46}^{+0.57}* 10^{-6} at (l,b)=(1.16, -2.75). Taking into account the measured gradient along the Galactic latitude b, tau = [ (4.48+/- 2.37) + (0.78+/- 0.84)* b]* 10^{-6}, this value is consistent with previous measurements using RCG sources and recent theoretical predictions. We determine the microlensing parameters and select events using a model light curve with the flux blending. We find that ~38% of the OGLE-II events which appear to have RCG sources are actually due to much fainter stars blended with a bright companion. We show explicitly that model fits without blending result in similar tau estimates through partial cancellation of contributions from higher detection efficiency, underestimated time-scales and larger number of selected events. This approach, however, leads to biased time-scale distributions and event rates. Consequently, microlensing studies should carefully consider source confusion effects even for bright stars.Comment: 49 pages and 18 figures, ApJ in press, the value changed due to the systematic correctio

Catalog of fundamental mode RR Lyrae stars in the Galactic bulge from the Optical Gravitational Lensing Experiment

We present a catalog of 1888 fundamental-mode RR Lyrae stars detected in the Galactic bulge fields of the second phase of the Optical Gravitational Lensing Experiment (OGLE). The catalog includes basic parameters of the light curves, identifications of Blazhko frequencies, V-I colors at minimum light (for most stars), and other information for each star. We detect a high rate of incidence of the Blazhko phenomenon (at least 27.6%), including unprecedentedly many frequency triplets, which we attribute to our sensitive search method. We find that the minimum light V-I color (useful as a reddening indicator) grows slowly redder with increasing period and exhibits a star-to-star scatter of approximately 0.07 mag. We use this color to evaluate the zero-point accuracy of the reddening map of the Galactic bulge derived from OGLE data, and find that in addition to low-level random errors or resolution effects (responsible for much of the scatter), the map may systematically over-represent E(V-I) by approximately 0.05 mag in most fields. We present reasonably robust evidence that the RR Lyrae-to-red clump color separation is larger by 0.05--0.08 mag in the bulge than locally, which argues for caution in the use of these stars for reddening determinations. We consider the RR Lyrae constraint on the Galactocentric distance, but uncertainty about the absolute magnitude calibration leaves significant flexibility in the result. In contrast to previous results, we robustly detect the signature of the Galactic bar in the RR Lyrae population within the inner plus/minus 3 degrees of longitude, and we highlight the apparent differences between the structures traced by the red clump giants and the more metal-poor RR Lyrae stars. (abridged)Comment: Submitted to ApJ, 34 pages aastex including 8 figures, full tables to appear electronically (temporarily available at http://www.astro.princeton.edu/~collinge/RR/

Self-trapped Exciton and Franck-Condon Spectra Predicted in LaMnO3_3

Because the ground state has cooperative Jahn-Teller order, electronic excitations in LaMnO$_3$ are predicted to self-trap by local rearrangement of the lattice. The optical spectrum should show a Franck-Condon series, that is, a Gaussian envelope of vibrational sidebands. Existing data are reinterpreted in this way. The Raman spectrum is predicted to have strong multiphonon features.Comment: 5 pages with two embedded postscript figure