An Oral History of Marie O. Ronen, a One-Room Schoolteacher

A transcript of an oral history of Marie O. Ronen, a one-room schoolteacher for Research in Education 803/https://scholars.fhsu.edu/ors/1290/thumbnail.jp

Implications of the Babinet Principle for Casimir Interactions

We formulate the Babinet Principle (BP) as a relation between the scattering amplitudes for electromagnetic waves, and combine it with multiple scattering techniques to derive new properties of Casimir forces. We show that the Casimir force exerted by a planar conductor or dielectric on a self- complementary perforated planar mirror is approximately half that on a uniform mirror independent of the distance between them. The BP suggests that Casimir edge effects are anomalously small, supporting results obtained earlier in special cases. Finally, we illustrate how the BP can be used to estimate Casimir forces between perforated planar mirrors

Artificial trapping of a stable high-density dipolar exciton fluid

We present compelling experimental evidence for a successful electrostatic trapping of two-dimensional dipolar excitons that results in stable formation of a well confined, high-density and spatially uniform dipolar exciton fluid. We show that, for at least half a microsecond, the exciton fluid sustains a density higher than the critical density for degeneracy if the exciton fluid temperature reaches the lattice temperature within that time. This method should allow for the study of strongly interacting bosons in two dimensions at low temperatures, and possibly lead towards the observation of quantum phase transitions of 2D interacting excitons, such as superfluidity and crystallization.Comment: 11 pages 4 figure

A-Model Correlators from the Coulomb Branch

We compute the contribution of discrete Coulomb vacua to A-Model correlators in toric Gauged Linear Sigma Models. For models corresponding to a compact variety, this determines the correlators at arbitrary genus. For non-compact examples, our results imply the surprising conclusion that the quantum cohomology relations break down for a subset of the correlators.Comment: 27 pages, 1 xy-pic figur

Perturbation of the Classic Binary Adduct C6H6:C6F6 by Chlorine Substitution

This paper presents a comprehensive exploration of the impact of monochlorine substitution on the solid-state phases of the classic binary adduct C6H6:C6F6. Crystal structures for all four phases of C6H6:C6F5Cl were determined using single-crystal X-ray diffraction, with complementary data from differential scanning calorimetry (DSC) and variable-temperature powder X-ray diffraction (VT-PXRD). The study reveals that phases I and III would have been overlooked without the additional information provided by DSC and PXRD. Symmetry changes during the phase transitions, including the loss of 3-fold and mirror symmetry, are crucial for our understanding of the observed transformations. Comparisons with the prototype C6H6:C6F6, the methyl-substituted C6H5CH3:C6F6 and iodine-substituted analogue C6H6:(C6F5I)2 provide useful insights into the noncovalent interactions holding these cocrystals together. The experimental results herein may be useful for informing crystal structure prediction, especially in distinguishing between structures of similar energy

Retinal metric: a stimulus distance measure derived from population neural responses

The ability of the organism to distinguish between various stimuli is limited by the structure and noise in the population code of its sensory neurons. Here we infer a distance measure on the stimulus space directly from the recorded activity of 100 neurons in the salamander retina. In contrast to previously used measures of stimulus similarity, this "neural metric" tells us how distinguishable a pair of stimulus clips is to the retina, given the noise in the neural population response. We show that the retinal distance strongly deviates from Euclidean, or any static metric, yet has a simple structure: we identify the stimulus features that the neural population is jointly sensitive to, and show the SVM-like kernel function relating the stimulus and neural response spaces. We show that the non-Euclidean nature of the retinal distance has important consequences for neural decoding.Comment: 5 pages, 4 figures, to appear in Phys Rev Let

Toward a script theory of guidance in computer-supported collaborative learning

This article presents an outline of a script theory of guidance for computer-supported collaborative learning (CSCL). With its four types of components of internal and external scripts (play, scene, role, and scriptlet) and seven principles, this theory addresses the question how CSCL practices are shaped by dynamically re-configured internal collaboration scripts of the participating learners. Furthermore, it explains how internal collaboration scripts develop through participation in CSCL practices. It emphasizes the importance of active application of subject matter knowledge in CSCL practices, and it prioritizes transactive over non-transactive forms of knowledge application in order to facilitate learning. Further, the theory explains how external collaboration scripts modify CSCL practices and how they influence the development of internal collaboration scripts. The principles specify an optimal scaffolding level for external collaboration scripts and allow for the formulation of hypotheses about the fading of external collaboration scripts. Finally, the article points towards conceptual challenges and future research questions

LEDGF/p75 is critical but not essential for multiple-round HIV 1 replication

status: publishe