Doping dependence of thermopower and thermoelectricity in strongly correlated systems

The search for semiconductors with high thermoelectric figure of merit has been greatly aided by theoretical modeling of electron and phonon transport, both in bulk materials and in nanocomposites. Recent experiments have studied thermoelectric transport in ``strongly correlated'' materials derived by doping Mott insulators, whose insulating behavior without doping results from electron-electron repulsion, rather than from band structure as in semiconductors. Here a unified theory of electrical and thermal transport in the atomic and ``Heikes'' limit is applied to understand recent transport experiments on sodium cobaltate and other doped Mott insulators at room temperature and above. For optimal electron filling, a broad class of narrow-bandwidth correlated materials are shown to have power factors (the electronic portion of the thermoelectric figure of merit) as high at and above room temperature as in the best semiconductors.Comment: 4 pages, 4 figure

Vortex Lattice Transitions in Cyclic Spinor Condensates

We study the energetics of vortices and vortex lattices produced by rotation in the cyclic phase of F=2 spinor condensates. In addition to the familiar triangular lattice predicted by Tkachenko for 4He, many more complex lattices appear in this system as a result of the spin degree of freedom. In particular, we predict a magnetic-field-driven transition from a triangular lattice to a honeycomb lattice. Other transitions and lattice geometries are driven at constant field by changes in the temperature-dependent ratio of charge and spin stiffnesses, including a transition through an aperiodic vortex structure. Finally, we compute the renormalization of the ratio of the spin and charge stiffnesses from thermal fluctuations using a nonlinear sigma model analysis

Pengembangan Instrumen Asesmen Pengetahuan Fisika Berbasis Komputer Untuk Meningkatkan Kesiapan Peserta Didik Dalam Menghadapi Ujian Nasional Berbasis Komputer

This research aims to 1) produce computer-based assessment instruments eligible to measure the cognitive abilities of senior high school students, 2) test the effectiveness of computer-based assessment instrument developed to measure the knowledge of physics in senior high school students, 3) measuring the level of readiness of students in dealing computer-based national examanation. This research uses a model of Research and Development (R & D) which consists of three main stages: the preliminary stage, the stage of development and evaluation phase. At the preliminary stage has been identified problems of computer-based assessment of learning physics. At the development stage has been carried out the design manufacture of computer-based assessment instrument physics, product validation, product revisions and testing of products on a limited basis. In the evaluation stage has been tested extensively, product revision, and the final product. Descriptive statistical test used to describe the results of the application of computer-based knowledge assessment. The results research show that : 1) computer-based assessment instruments eligible to measure cognitive abilities of senior high school students, 2) computer-based assessment instruments are more effective and efficient to measure the students knowledge of physics in senior high school rather than paper and pencil test, 3) 58.67% of students are ready to face computer-based test, 34% of students not yet ready for the computer based test and 7.33% are not ready to perform the test based computer

The Equivalence of Translated Songs Lyrics and Their Effects - the Case of Translated Ecclesial Songs

This study aimed at describing the equivalence of eclessial song lyrics, which belong to the content word, the meaning of the sentences and their effect on church songs. The method used in this study is descriptive and qualitative by using music, language, and interdiciline approach. The data collection method used questionnaires technique, interview, documents and content analysis. The data used are 5 documents of songs chosen purposively as the primary data. Based on the data being analyzed, the results of this study were: 1) The translated content word located in the same bars and equivalent was around 27.07%, the translated content word located in the same bars, but not equivalent was 18.34%, the translated content word located in the different bars, but equivalent was 11.79%, the translated content word located in the different bars and not equivalent was 2.62%, and the untranslated words were 4.17%. 2) The translation of equivalence beautiful lyrics showed the beauty of the song was equivalent at 17.02%, the beauty of the song was less equivalent at 29.78%, the beauty of the song was not equivalent of 61.70%. 3). The differences of structure caused the incorrect dictions or choice of words and missing words in the translated lyrics

Dynamics after a sweep through a quantum critical point

The coherent quantum evolution of a one-dimensional many-particle system after sweeping the Hamiltonian through a critical point is studied using a generalized quantum Ising model containing both integrable and non-integrable regimes. It is known from previous work that universal power laws appear in such quantities as the mean number of excitations created by the sweep. Several other phenomena are found that are not reflected by such averages: there are two scaling regimes of the entanglement entropy and a relaxation that is power-law rather than exponential. The final state of evolution after the quench is not well characterized by any effective temperature, and the Loschmidt echo converges algebraically to a constant for long times, with cusplike singularities in the integrable case that are dynamically broadened by nonintegrable perturbations.Comment: 4 pages, 4 figure

Analisis Pengaruh Perubahan Sentrasi Dosis dan Jarak Bladder terhadap Distribusi Dosis pada Perencanaan Brachytherapy Kanker Serviks

The research has been done about the analysis of the change dose sentration and bladder distance\u27s effect toward dose distribution in brachytherapy planning of cervical cancer. The purpose of this research is to describing dose distribution which is appropriate with criteria, to evidance dose reduction because raising bladder distance from point A, and to achieve how long the bladder distance\u27s from point A which is can produce the dose distribution criteria appropriate.The methods of this research is measuring bladder distance from point A in lateral projections of radiographs, doing brachytherapy planning which is using early dose sentration at the point A. The sample who is have not ideal dose disribution doing brachytherapy planning with dose sentration at point bladder. The dose distribution which is producted from the change of dose sentration has analysis to know how about brachytherapy planning succes percentage. To evidance about dose reduction because raising of bladder distance\u27s, has done with making distance and bladder dose\u27s relation graph.The results of this research is: changing of dose sentration can increasing cervical brachytherapy planing successed about 46%, raising mean distance about 1,57 mm can reduce bladder mean dose about 5,65%, inverse square law still valid for brachytherapy planning case\u27s although can\u27t used to determine how much dose at the bladder, bladder distance from point A which is can deliver dose percentage lower about 80% is more than 41 mm

Towards a statistical theory of transport by strongly-interacting lattice fermions

We present a study of electric transport at high temperature in a model of strongly interacting spinless fermions without disorder. We use exact diagonalization to study the statistics of the energy eigenvalues, eigenstates, and the matrix elements of the current. These suggest that our nonrandom Hamiltonian behaves like a member of a certain ensemble of Gaussian random matrices. We calculate the conductivity $\sigma(\omega)$ and examine its behavior, both in finite size samples and as extrapolated to the thermodynamic limit. We find that $\sigma(\omega)$ has a prominent non-divergent singularity at $\omega=0$ reflecting a power-law long-time tail in the current autocorrelation function that arises from nonlinear couplings between the long-wavelength diffusive modes of the energy and particle number