Elementary Excitations in One-Dimensional Electromechanical Systems; Transport with Back-Reaction

Using an exactly solvable model, we study low-energy properties of a one-dimensional spinless electron fluid contained in a quantum-mechanically moving wire located in a static magnetic field. The phonon and electric current are coupled via Lorentz force and the eigenmodes are described by two independent boson fluids. At low energies, the two boson modes are charged while one of them has excitation gap due to back-reaction of the Lorentz force. The theory is illustrated by evaluating optical absorption spectra. Our results are exact and show a non-perturbative regime of electron transport

Will Nonlinear Peculiar Velocity and Inhomogeneous Reionization Spoil 21cm Cosmology from the Epoch of Reionization?

The 21cm background from the epoch of reionization is a promising cosmological probe: line-of-sight velocity fluctuations distort redshift, so brightness fluctuations in Fourier space depend upon angle, which linear theory shows can separate cosmological from astrophysical information. Nonlinear fluctuations in ionization, density and velocity change this, however. The validity and accuracy of the separation scheme are tested here for the first time, by detailed reionization simulations. The scheme works reasonably well early in reionization ( 80% ionized).Comment: 2 figures, matches published PRL versio

An Investigation into Pre-Training Object-Centric Representations for Reinforcement Learning

Unsupervised object-centric representation (OCR) learning has recently drawn attention as a new paradigm of visual representation. This is because of its potential of being an effective pre-training technique for various downstream tasks in terms of sample efficiency, systematic generalization, and reasoning. Although image-based reinforcement learning (RL) is one of the most important and thus frequently mentioned such downstream tasks, the benefit in RL has surprisingly not been investigated systematically thus far. Instead, most of the evaluations have focused on rather indirect metrics such as segmentation quality and object property prediction accuracy. In this paper, we investigate the effectiveness of OCR pre-training for image-based reinforcement learning via empirical experiments. For systematic evaluation, we introduce a simple object-centric visual RL benchmark and conduct experiments to answer questions such as ``Does OCR pre-training improve performance on object-centric tasks?'' and ``Can OCR pre-training help with out-of-distribution generalization?''. Our results provide empirical evidence for valuable insights into the effectiveness of OCR pre-training for RL and the potential limitations of its use in certain scenarios. Additionally, this study also examines the critical aspects of incorporating OCR pre-training in RL, including performance in a visually complex environment and the appropriate pooling layer to aggregate the object representations.Comment: We study unsupervised object-centric representations in reinforcement learning through systematic investigatio

Dynamical electron transport through a nanoelectromechanical wire in a magnetic field

We investigate dynamical transport properties of interacting electrons moving in a vibrating nanoelectromechanical wire in a magnetic field. We have built an exactly solvable model in which electric current and mechanical oscillation are treated fully quantum mechanically on an equal footing. Quantum mechanically fluctuating Aharonov-Bohm phases obtained by the electrons cause nontrivial contribution to mechanical vibration and electrical conduction of the wire. We demonstrate our theory by calculating the admittance of the wire which are influenced by the multiple interplay between the mechanical and the electrical energy scales, magnetic field strength, and the electron-electron interaction

How Long Does It Take to Master Laryngeal Visualization Using Flexible Nasolaryngoscopy in Children?

Background: To assess when residents become proficient in performing flexible nasolaryngoscopy (FNL) in the pediatric population. Objective: To objectively evaluate the quality of FNL by year of residency training. Methods: Ninety-five pediatric FNL’s were performed by otolaryngology residents and pediatric otolaryngology fellows (post-graduate year [PGY] 1 – 6). Three pediatric otolaryngologists rated the FNL videos (anonymized and without sound) using the Modified Cormack‐Lehane scoring system (MCLS). Data analysis was performed using two-way ANOVA and Tukey-Kramer adjustment. Results: Overall, there was a significant difference in the quality of the FNL based on the year of training (p\u3c0.0001). Comparing specific years, there was a statistically significant difference between PGY-1 and PGY-2 (p=0.004); however, there was no difference between years of training beyond the PGY-2 year. Conclusion: The quality of pediatric FNL improves after the PGY -1 year. Current training consists of the traditional “see one, do one, teach one” rubric. Future educational goals should focus on developing a curriculum to shorten the time to achieve proficiency in pediatric FNL

A Systematic Review of Pica and Geophagy in Japan and Korea

Pica, the craved and purposive consumption of non-food substances, is a globally widespread behavior that has critical connections to public health. Although there is a rich literature describing these behaviors from nearly every culture around the world, there is a dearth of English language literature reporting these behaviors in Japan and Korea. Here, we systematically reviewed the medical evidence of pica in Korean and Japanese language journals to confirm their presence in these cultures and to characterize culturally-specific factors associated with these behaviors. We used Ichusi-Web and KoreaMed with a broad variety of recombined search terms including “pica,” “geophagy,” “amylophagy,” and “trichobezoar” in Korean and Japanese characters. Our results confirm that pica is present in both of these cultures, with particularly frequent reports of trichobezoar (the consumption of human hair)