On the disintegration of cosmic ray nuclei by solar photons

We discuss in detail the possibility of observing pairs of simultaneous parallel air showers produced by the fragments of cosmic ray nuclei which disintegrated in collisions with solar photons. We consider scenarios with different cosmic ray compositions, exploring the predicted rates for existing and planned detectors and looking for methods to extract information on the initial composition from the characteristics of the signal. In particular, we find that fluorescence detectors, such as HiRes or the Telescope Array, due to their low threshold ($\sim 10^{17}$ eV) and large area ($\sim 10^4 km^2$) may observe several events per year if cosmic rays at those energies are indeed heavy nuclei. The possibility of exploiting the angular orientation of the plane containing the two showers to further constrain the cosmic ray composition is also discussed.Comment: 15 page

Power accretion in social systems

We consider a model of power distribution in a social system where a set of agents plays a simple game on a graph: The probability of winning each round is proportional to the agent’s current power, and the winner gets more power as a result. We show that when the agents are distributed on simple one-dimensional and two-dimensional networks, inequality grows naturally up to a certain stationary value characterized by a clear division between a higher and a lower class of agents. High class agents are separated by one or several lower class agents which serve as a geometrical barrier preventing further flow of power between them. Moreover, we consider the effect of redistributive mechanisms, such as proportional (nonprogressive) taxation. Sufficient taxation will induce a sharp transition towards a more equal society, and we argue that the critical taxation level is uniquely determined by the system geometry. Interestingly, we find that the roughness and Shannon entropy of the power distributions are a very useful complement to the standard measures of inequality, such as the Gini index and the Lorenz curveWe acknowledge financial support from the Spanish Government through Grants No. FIS2015-69167-C2-1-P, No. FIS2015-66020-C2- 1-P, and No. PGC2018-094763-B-I0

Flux through a time-periodic gate: Monte Carlo test of a homogenization result

We investigate via Monte Carlo numerical simulations and theoretical considerations the outflux of random walkers moving in an interval bounded by an interface exhibiting channels (pores, doors) which undergo an open/close cycle according to a periodic schedule. We examine the onset of a limiting boundary behavior characterized by a constant ratio between the outflux and the local density, in the thermodynamic limit. We compare such a limit with the predictions of a theoretical model already obtained in the literature as the homogenization limit of a suitable diffusion problem

La comunidad por-venir

El presente ensayo reflexiona sobre el concepto de comunidad y sobre las formas de pensamiento en grado de interrumpir la totalizadora y a menudo violenta homogeneidad de la identidad (o de la diferencia), es decir, sobre la prioridad del sujeto y el pap

The Effect of a Standardized Handoff Tool on Communication, Interunit Transitions, and Wait Time: A Quality Improvement Project

This project sought not only to improve the communication and interunit transitions of care between emergency department providers (EDPs) and inpatient providers (IPs) using a standardized handoff tool, but also to reduce the Emergency Room (ED) wait time for patients admitted to the community hospital. The project employed a quantitative quasi-experimental pre-test/post-test design to explore provider satisfaction with an evidence-based standardized handoff tools and wait time. Forty-eight providers completed the survey before the I-PASS implementation, and 43 providers completed the survey post I-PASS implementation. Though not statistically significant, data indicates that wait time increased for the post-implementation months of December, January, and February 2022 when compared with pre-implementation months of February, March, and April of the previous year. From the discussion with the facility quality team, the increase in weight time is mainly due to nursing staffing and vacancies rates. Significant positive differences were seen in 18 of the 19 items on the provider satisfaction survey indicating that providers were more satisfied with handoff using the I-PASS tool than prior to implementation of the standardized tool. The only exception was that the agreement for need of standardized handoff tool was not significantly different in comparing pre and post survey responses. Findings from this project support the need for a standardized handoff tool in ED. Prior to the implementation of the tool, providers described missing information, inaccurate information, and incomplete care plans in handoffs. The I-PASS tool addressed all these items and was easy to use

Influence of the notch-sharpening technique on styrene-acrylonitrile fracture behavior

The Centre Catala del Plastic and Universidad Rey Juan Carlos laboratories joined forces to investigate the effect of the notch-sharpening technique on the fracture parameters of styrene-acrylonitrile. Contact notch-sharpening techniques, such as razor tapping, razor sliding, and razor broaching, and a noncontact procedure, femtolaser, were analyzed. The fracture values of the samples with notches sharpened via contact techniques were divided into two groups: one with pop-in and the other with no pop-in in the load-displacement records; this resulted in the lowest and highest fracture toughnesses, respectively. The fracture parameters of the specimens with notches sharpened via a femtolaser were between those of the samples with notches sharpened via contact procedures in which pop-in occurred and those in which it did not. To explain these results, the crack front of the nontested specimens after sharpening was investigated in depth, we identified the type of damage and measured its size and the crack tip radii. The morphology of the crack front was related to the fractographic study.Postprint (author's final draft