Theoretical and material studies on thin-film electroluminescent devices

During this report period work was performed on the modeling of High Field Electronic Transport in Bulk ZnS and ZnSe, and also on the surface cleaning of Si for MBE growth. Some MBE growth runs have also been performed in the Varian GEN II System. A brief outline of the experimental work is given. A complete summary will be done at the end of the next reporting period at the completion of the investigation. The theoretical studies are included

Composite Fermions in Quantum Dots

We demonstrate the formation of composite fermions in two-dimensional quantum dots under high magnetic fields. The composite fermion interpretation provides a simple way to understand several qualitative and quantitative features of the numerical results obtained earlier in exact diagonalization studies. In particular, the ground states are recognized as compactly filled quasi-Landau levels of composite fermions.Comment: Revtex. Postscript files of figures are appended the tex

The Friendly Media Phenomenon: A Cross-National Analysis of Cross-Cutting Exposure

We hypothesize that in the real world, as opposed to the lab, the norm is for people to experience friendly media that favor their political predispositions when political favoritism is perceived at all. For this reason, media are generally limited in their ability to create cross-cutting exposure. We test this hypothesis using representative survey data drawn from 11 different countries with varying media systems. We further hypothesize that television will contribute more to cross-cutting exposure than newspapers. Finally, and most importantly, we test the hypothesis that the more the structure of a country’s media system parallels that of its political parties, the more that country’s population will be dominated by exposure to like-minded views via mass media. We find confirmation for all 3 of these hypotheses and discuss their implications for the role of mass media in providing exposure to cross-cutting political perspectives

Effects of Mass Media on Prejudice

The way outgroup members are portrayed in the media is widely believed to have consequences for levels of prejudice and stereotyping in the mass public. The visual nature of television and its heavy viewership make it a key source of information for impressions that ingroup members may have of other social groups. However, most research to date has focused on documenting the portrayals of various groups in television content, with only a few studies documenting the causal impact of television viewing. To further understanding of this hypothesis, we outline the contributions and limitations of past work, and point to the most promising theoretical frameworks for studying media influence on outgroup attitudes

All Virtue is Relative: A Response to Prior

In “The Challenge of Measuring Media Exposure: Reply to Dilliplane, Goldman, and Mutz,” Markus Prior suggests that scholars should avoid using a new method of measuring exposure to political television that we evaluated in a recent article published in the American Journal of Political Science. We respond to each of his criticisms, concluding that although no measurement approach is without its flaws, scholars should always use the best approach that is available at any given point in time

Valence Quark Distribution in A=3 Nuclei

We calculate the quark distribution function for 3He/3H in a relativistic quark model of nuclear structure which adequately reproduces the nucleon approximation, nuclear binding energies, and nuclear sizes for small nuclei. The results show a clear distortion from the quark distribution function for individual nucleons (EMC effect) arising dominantly from a combination of recoil and quark tunneling effects. Antisymmetrization (Pauli) effects are found to be small due to limited spatial overlaps. We compare our predictions with a published parameterization of the nuclear valence quark distributions and find significant agreement.Comment: 18pp., revtex4, 4 fig

Non-thermal origin of nonlinear transport across magnetically induced superconductor-metal-insulator transition

We have studied the effect of perpendicular magnetic fields and temperatures on the nonlinear electronic transport in amorphous Ta superconducting thin films. The films exhibit a magnetic field induced metallic behavior intervening the superconductor-insulator transition in the zero temperature limit. We show that the nonlinear transport in the superconducting and metallic phase is of non-thermal origin and accompanies an extraordinarily long voltage response time.Comment: 5 pages, 4 figure

Observation of discrete energy levels in a quantum confined system

Low temperature scanning tunneling microscope images and spectroscopic data have been obtained on subnanometer size Pb clusters fabricated using the technique of buffer layer assisted growth. Discrete energy levels were resolved in current-voltage characteristics as current peaks rather than current steps. Distributions of peak voltage spacings and peak current heights were consistent with Wigner-Dyson and Porter-Thomas distributions respectively, suggesting the relevance of random matrix theory to the description of the electronic eigenstates of the clusters. The observation of peaks rather than steps in the current-voltage characteristics is attributed to a resonant tunneling process involving the discrete energy levels of the cluster, the tip, and the states at the interface between the cluster and the substrate surface.Comment: 4 pages, 4 figure

Text-based Editing of Talking-head Video

Editing talking-head video to change the speech content or to remove filler words is challenging. We propose a novel method to edit talking-head video based on its transcript to produce a realistic output video in which the dialogue of the speaker has been modified, while maintaining a seamless audio-visual flow (i.e. no jump cuts). Our method automatically annotates an input talking-head video with phonemes, visemes, 3D face pose and geometry, reflectance, expression and scene illumination per frame. To edit a video, the user has to only edit the transcript, and an optimization strategy then chooses segments of the input corpus as base material. The annotated parameters corresponding to the selected segments are seamlessly stitched together and used to produce an intermediate video representation in which the lower half of the face is rendered with a parametric face model. Finally, a recurrent video generation network transforms this representation to a photorealistic video that matches the edited transcript. We demonstrate a large variety of edits, such as the addition, removal, and alteration of words, as well as convincing language translation and full sentence synthesis

Bose-Einstein Condensation of Atoms in a Trap

We point out that the local density approximation (LDA) of Oliva is an adaptation of the Thomas-Fermi method, and is a good approximation when $\varepsilon = \hbar\omega/kT 0$, the LDA leads to a quantitative result (14') easily checked by experiments. Critical remarks are made about the physics of the many body problem in terms of the scattering length $a$.Comment: 9 pages, latex. one figure, available from author