Incoherent ensemble dynamics in disordered systems

We derive a quantum master equation which describes the dynamics of the ensemble-averaged state of homogeneous disorder models at short times, and mediates a transition from coherent superpositions into classical mixtures. While each single realization follows unitary dynamics, this decoherencelike behavior arises as a consequence of the ensemble average. The master equation manifestly reflects the translational invariance of the disorder correlations and allows us to relate the disorder-induced dynamics to a collisional decoherence process, where the disorder correlations determine the spatial decay of coherences. We apply our theory to the (one-dimensional) Anderson model.Comment: 7 page

Review of \u3cem\u3eWhat\u27s Happening to Public Higher Education?\u3c/em\u3e edited by R.G. Ehrenberg

Book Review of: Ehrenberg, R.G. (Ed.). (2006). What\u27s Happening to Public Higher Education?. Westport, CT: Praeger Publishers

Exploring Living-Learning Communities as a Venue for Men’s Identity Construction.

THIS QUALITATIVE STUDY EXPLORED how male undergraduate students experienced living-learning community environments. Findings revealed that living-learning communities provided men a safe haven from rigid gender role expectations, offered a plethora of involvement opportunities, and fostered relationships with faculty and peers. The findings highlight the potential of living-learning communities to provide men with the support they need to reject rigid gender expectations and develop a healthy identity. Recommendations for practice are discussed

Enhancing Undergraduate Education: Examining Faculty Experiences During Their First Year in a Residential College and Exploring the Implications for Student Affairs Professionals

The article discusses the results of a study on the experiences and insights of faculty members in a new residential college. The researchers used a constructivist, case study method to determine how faculty made meaning of their experiences in a residential college at a major, land-grant research university in the Midwest U.S. The findings of the study indicate that the residential college environment did not ameliorate the time pressures experienced by faculty

From Expectations to Experiences: Using a Structural Typology to Understand First-Year Student Outcomes in Academically Based Living-Learning Communities

This longitudinal study investigated to what extent noncognitive variables (e.g., expectations for college) and the college environment (i.e., academically based living-learning communities) influence students\u27 college experience. This research goes beyond grouping all living-learning students into one category, which has dominated much of the literature, by using an empirically derived structural typology for living-learning communities (Inkelas, Longerbeam, Leonard, & Soldner, 2005). Results suggest that being a student in a collaborative living-learning community is more likely to predict greater peer academic interactions and an enriching educational environment. Implications for practice and future research are discussed

Exploring Students\u27 Perceptions of Academically Based Living-Learning Communities

This qualitative study employed focus group interviews to explore students\u27 perceptions of three well established academically based living-learning communities at a large, land-grant university in the Midwest. Three themes emerged that illustrated students\u27 perceptions of a culture that promoted seamless learning, a scholarly environment, and an ethos of relatedness among faculty, staff, and peers. Implications for practice and future research are discussed

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene

We present optical absorption spectra of mixed films of pentacene (PEN) and perfluoropentacene (PFP) grown on SiO2. We investigated the influence of intermolecular coupling between PEN and PFP on the optical spectra by analyzing samples with five different mixing ratios of PFP:PEN with variable angle spectroscopic ellipsometry (VASE) and differential reflectance spectroscopy (DRS). The data show how the spectral shape is influenced by changes in the volume ratio of the two components. By comparison with the pure film spectra an attempt is made to distinguish transitions due to intermolecular coupling between PEN and PFP from transitions caused by interactions of PEN (PFP) with other molecules of the same type. We observe a new transition at 1.6 eV which is not found in the pure film spectra and which we assign to coupling of PFP and PEN.Comment: 6 pages, 6 figures, 1 table, accepted for publication in Phys. Rev.

Photoluminescence spectroscopy of pure pentacene, perfluoropentacene and mixed thin films

We report detailed temperature dependent photoluminescence (PL) spectra of pentacene (PEN), perfluoropentacene (PFP), and PEN:PFP mixed thin films grown on SiO2. PEN and PFP are particularly suitable for this study, since they are structurally compatible for good intermixing and form a model donor/acceptor system. The PL spectra of PEN are discussed in the context of existing literature and compared to the new findings for PFP. We analyze the optical transitions observed in the spectra of PEN and PFP using time-dependent density functional theory (TD-DFT) calculations. Importantly, for the mixed PEN:PFP film we observe an optical transition in PL at 1.4 eV providing evidence for coupling effects in the blend. We discuss a possible charge-transfer (CT) and provide a tentative scheme of the optical transitions in the blended films.Comment: 9 pages, 6 figures, accepted for publication in J. Chem. Phy