Quantum Zeno Effect Explains Magnetic-Sensitive Radical-Ion-Pair Reactions

Chemical reactions involving radical-ion pairs are ubiquitous in biology, since not only are they at the basis of the photosynthetic reaction chain, but are also assumed to underlie the biochemical magnetic compass used by avian species for navigation. Recent experiments with magnetic-sensitive radical-ion pair reactions provided strong evidence for the radical-ion-pair magnetoreception mechanism, verifying the expected magnetic sensitivities and chemical product yield changes. It is here shown that the theoretical description of radical-ion-pair reactions used since the 70's cannot explain the observed data, because it is based on phenomenological equations masking quantum coherence effects. The fundamental density matrix equation derived here from basic quantum measurement theory considerations naturally incorporates the quantum Zeno effect and readily explains recent experimental observations on low- and high-magnetic-field radical-ion-pair reactions.Comment: 10 pages, 5 figure

Movement and Countermovement Dynamics Between the Religious Right and LGB Community Arising from Colorado’s Amendment 2

This sample of the case study of Equality Colorado will demonstrate how counter movements and litigation may limit and change how an organization surrounding a social movement acts. Colorado for Family Values helped pass Colorado’s Amendment 2 in 1992, which limited any present and future anti-discrimination legislation that would protect sexuality as a class. This ballot initiative passed by 53% of Colorado voters, and other states like Idaho and Oregon attempted to replicate this type of initiative. Amendment 2 challenged the LGB community and compelled the movement to collectively respond to the religious right with coalitions, pooled resources, and litigation. Equality Colorado, established in 1992, will exemplify how a social movement could respond to prejudicial legislation. One of Equality Colorado’s primary tactics was to reframe religion as inclusive of gay rights. It did not cede religion entirely to its opponents and attempted to delegitimize them by labeling them “radical right” as opposed to the more popular term “religious right” or “Christian Conservatives”. Additionally, Equality Colorado tried to compensate for the downsides of litigation by “translating” the legal terms to the general public and connecting litigators with the broader movement

Generalized Holstein model for spin-dependent electron transfer reaction

Some chemical reactions are described by electron transfer (ET) processes. The underlying mechanism could be modeled as a polaron motion in the molecular crystal-the Holstein model. By taking spin degrees of freedom into consideration, we generalize the Holstein model (molecular crystal model) to microscopically describe an ET chemical reaction. In our model, the electron spins in the radical pair simultaneously interact with a magnetic field and their nuclear-spin environments. By virtue of the perturbation approach, we obtain the chemical reaction rates for different initial states. It is discovered that the chemical reaction rate of the triplet state demonstrates its dependence on the direction of the magnetic field while the counterpart of the singlet state does not. This difference is attributed to the explicit dependence of the triplet state on the direction when the axis is rotated. Our model may provide a possible candidate for the microscopic origin of avian compass.Comment: 9 pages, 6 figure

Responses of Ileal and Fecal Microbiota to Withdrawal of Pancreatic Enzyme Replacement Therapy in a Porcine Model of Exocrine Pancreatic Insufficiency

Little is known regarding the interplay between microbiota and pancreas functions in humans as investigations are usually limited to distal sites, namely the analyses of fecal samples. The aim of this study was to investigate both ileal and fecal microbiota in response to pancreatic enzyme replacement therapy (PERT) in a porcine model of exocrine pancreatic insufficiency (EPI). PERT was stopped for ten days in ileo-cecal fistulated minipigs with experimentally induced EPI (n = 8) and ileal digesta as well as fecal samples were obtained before withdrawal, during withdrawal and after the reintroduction of PERT. Profound community changes occurred three days after enzyme omission and were maintained throughout the withdrawal phase. A reduction in α-diversity together with relative abundance changes in several taxa, in particular increases in Bifidobacteria (at both sites) and Lactobacilli (only feces) were observed. Overall, dysbiosis events from the ileum had accumulating effects in distal parts of the gastrointestinal tract with additional alterations occurring only in the colon. Changes were reversible after continuing PERT, and one week later, bacterial communities resembled those at baseline. Our study demonstrates the rapid and profound impacts of enzyme withdrawal in bacterial communities, contributing to our understanding of the interplay between pancreas function and microbiot

Retention of Physician Assistants within a Specialty after Completion of a Postgraduate Training Program

Background: The advantages of a specialized training program have led to over 84 postgraduate training programs for Physician Assistants (PAs) covering over 25 specialties. Employee lateral mobility is more prevalent within the PA profession, which allows PA providers to switch between medical specialties. The versatility of PAs promotes higher turnover rates compared to physician counterparts. These high turnover rates can result in increased institutional burden. Postgraduate PA programs provide pre-employment exposure to more in-depth medical training, enabling a well-rounded knowledge base of the PA’s roles and responsibilities, minimizing turnover rates. Purpose: The goal of this survey study is to identify PA graduates’ perceptions of their retention rate, job satisfaction within a given specialty, factors influencing a PA’s decision to change their specialty, and specialty preparation provided by postgraduate training programs and specific educational training. Methods: A mixed method design was utilized to survey both program directors and graduates of PA postgraduate training programs. Results: Of the 398 postgraduate program graduates, 196 (49%) accepted a job within the institution where they trained. Across all postgraduate training programs, 87% of graduates have not changed their specialty since program completion. Ninety-six percent of respondents felt their postgraduate training gave them an accurate preview of employment in their specialty of interest, and all postgraduates would recommend a postgraduate training program to a new PA graduate

Generating non-Gaussian maps with a given power spectrum and bispectrum

We propose two methods for generating non-Gaussian maps with fixed power spectrum and bispectrum. The first makes use of a recently proposed rigorous, non-perturbative, Bayesian framework for generating non-Gaussian distributions. The second uses a simple superposition of Gaussian distributions. The former is best suited for generating mildly non-Gaussian maps, and we discuss in detail the limitations of this method. The latter is better suited for the opposite situation, i.e. generating strongly non-Gaussian maps. The ensembles produced are isotropic and the power spectrum can be jointly fixed; however we cannot set to zero all other higher order cumulants (an unavoidable mathematical obstruction). We briefly quantify the leakage into higher order moments present in our method. We finally present an implementation of our code within the HEALPIX packageComment: 22 pages submitted to PRD, astro-ph version only includes low resolution map

Ligand Migration and Cavities within Scapharca Dimeric HbI: Studies by Time-Resolved Crystallo- graphy, Xe Binding, and Computational Analysis

SummaryAs in many other hemoglobins, no direct route for migration of ligands between solvent and active site is evident from crystal structures of Scapharca inaequivalvis dimeric HbI. Xenon (Xe) and organic halide binding experiments, along with computational analysis presented here, reveal protein cavities as potential ligand migration routes. Time-resolved crystallographic experiments show that photodissociated carbon monoxide (CO) docks within 5 ns at the distal pocket B site and at more remote Xe4 and Xe2 cavities. CO rebinding is not affected by the presence of dichloroethane within the major Xe4 protein cavity, demonstrating that this cavity is not on the major exit pathway. The crystal lattice has a substantial influence on ligand migration, suggesting that significant conformational rearrangements may be required for ligand exit. Taken together, these results are consistent with a distal histidine gate as one important ligand entry and exit route, despite its participation in the dimeric interface