Uniform Semiclassical Wavepacket Propagation and Eigenstate Extraction in a Smooth Chaotic System

A uniform semiclassical propagator is used to time evolve a wavepacket in a smooth Hamiltonian system at energies for which the underlying classical motion is chaotic. The propagated wavepacket is Fourier transformed to yield a scarred eigenstate.Comment: Postscript file is tar-compressed and uuencoded (342K); postscript file produced is 1216

Présentation Shibboleth

Présenté dans le cadre de la journée d’information à l’intention des membres du personnel des bibliothèques universitaires québécoises : "La bibliothèque de recherche virtuelle québécoise (BRVQ) : une vision commune d’une réalisation en devenir "Présentation vulgarisée pour faire apparaitre le potentiel de transformation de service et de soutien de services communs d'une pareille infrastructure

Lithium depletion in the sun

Physical properties of non-standard solar models including pre-main sequence phase, penetrative convention and microscopic diffusion are presented.We emphasize on 7Li depletion

Phase Aberration Correction for in vivo Ultrasound Localization Microscopy Using a Spatiotemporal Complex-Valued Neural Network

Ultrasound Localization Microscopy (ULM) can map microvessels at a resolution of a few micrometers ({\mu}m). Transcranial ULM remains challenging in presence of aberrations caused by the skull, which lead to localization errors. Herein, we propose a deep learning approach based on recently introduced complex-valued convolutional neural networks (CV-CNNs) to retrieve the aberration function, which can then be used to form enhanced images using standard delay-and-sum beamforming. Complex-valued convolutional networks were selected as they can apply time delays through multiplication with in-phase quadrature input data. Predicting the aberration function rather than corrected images also confers enhanced explainability to the network. In addition, 3D spatiotemporal convolutions were used for the network to leverage entire microbubble tracks. For training and validation, we used an anatomically and hemodynamically realistic mouse brain microvascular network model to simulate the flow of microbubbles in presence of aberration. We then confirmed the capability of our network to generalize to transcranial in vivo data in the mouse brain (n=2). Qualitatively, vascular reconstructions using a pixel-wise predicted aberration function included additional and sharper vessels. The spatial resolution was evaluated by using the Fourier ring correlation (FRC). After correction, we measured a resolution of 16.7 {\mu}m in vivo, representing an improvement of up to 27.5 %. This work leads to different applications for complex-valued convolutions in biomedical imaging and strategies to perform transcranial ULM

Change and Continuity in the Role of State Attorneys General in the Obama and Trump Administrations

During the Trump Administration, state attorneys general (AGs) have become entrenched as integral policymaking actors in the United States. Their expanding policymaking role fits broader patterns of polarized politics, as partisan coalitions of AGs are increasingly willing to sue the federal government, a trend that gathered steam in the Obama Administration and has reached a crescendo in Trump’s first year. However, state AGs do cooperate, particularly in corporate litigation to address allegedly widespread, illegal behavior. Utilizing a comprehensive dataset of multi-state lawsuits and Supreme Court amicus briefs, we identify continuity and change in how AGs have employed their powers, by examining their activities during the first year of the Trump presidency and placing these activities in the context of previous administrations. This analysis is accompanied by a pair of case studies, one on conflictual AG environmental litigation and another on bipartisan efforts to address the opioid epidemic. Both demonstrate AG’s prominent policymaking power, a power unlikely to abate anytime soon

A multi-site campaign to measure solar-like oscillations in Procyon. II. Mode frequencies

We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with eleven telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called echelle diagram reveals two clear ridges that we identify with even and odd values of the angular degree (l=0 and 2, and l=1 and 3, respectively). We interpret a strong, narrow peak at 446 muHz that lies close to the l=1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of about 1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29 +0.55/-0.49 days, which is significantly shorter than the 2-4 days seen in the Sun.Comment: accepted for publication in Ap

International meta-analysis of PTSD genome-wide association studies identifies sex- and ancestry-specific genetic risk loci.

The risk of posttraumatic stress disorder (PTSD) following trauma is heritable, but robust common variants have yet to be identified. In a multi-ethnic cohort including over 30,000 PTSD cases and 170,000 controls we conduct a genome-wide association study of PTSD. We demonstrate SNP-based heritability estimates of 5-20%, varying by sex. Three genome-wide significant loci are identified, 2 in European and 1 in African-ancestry analyses. Analyses stratified by sex implicate 3 additional loci in men. Along with other novel genes and non-coding RNAs, a Parkinson's disease gene involved in dopamine regulation, PARK2, is associated with PTSD. Finally, we demonstrate that polygenic risk for PTSD is significantly predictive of re-experiencing symptoms in the Million Veteran Program dataset, although specific loci did not replicate. These results demonstrate the role of genetic variation in the biology of risk for PTSD and highlight the necessity of conducting sex-stratified analyses and expanding GWAS beyond European ancestry populations

The Golden Age of European Cabaret

Program for the second annual RISD Cabaret held in the Cellar in the Pit. Design and layout by Anne Johnson, Susan Sellers and Georgie Stout.https://digitalcommons.risd.edu/liberalarts_cabaret_programs/1001/thumbnail.jp