Sexual and size dimorphism in two deep-water hermit crabs (Decapoda: Parapaguridae) from the Western Atlantic Ocean

Abstract The Parapaguridae comprises hermit crabs that inhabit deep-water environments. In these environments, shell availability can be limited, mostly consisting of small and fragile-shelled gastropods. Thus, different strategies have evolved to mitigate this limited shell supply. Sympagurus dimorphus (Studer, 1883) lives in association with a zoanthid cnidarian that creates a pseudo-shell that grows with the hermit crab. In contrast, Oncopagurus gracilis (Henderson, 1888) inhabits small, calcified gastropod shells. Therefore, we selected these two species as models to test sexual dimorphism and shape patterns of their chelipeds and cephalothoracic shield, due to their different shelter acquisition methods. We photographed the animals and digitized the images to employ comparative geometric morphometric techniques. We tested the differences in shape between the sexes within each species, and also tested sexual size dimorphism based on centroid size. For O. gracilis, we found shape differences for the chelipeds and cephalothoracic shield, however, we only observed sexual size dimorphism for the chelipeds. For S. dimorphus, an inverse pattern was found, in which females presented more robust chelipeds, and sexual size dimorphism was present in which males were larger. These differences can be reasonably explained by their shelter acquisition methods, in which O. gracilis depends on small shells that limit growth, while S. dimorphus grows with its cnidarian pseudo-shell. The robustness found in the shape patterns may also be related to their behaviors, e.g., in addition to competition for shells, they also fight during mating. However, we emphasize that future studies with other populations of these species are needed for comparative purposes

Conditions for efficient charge generation preceded by energy transfer process in non-fullerene organic solar cells

The minimum driving force strategy is applied to promote the exciton dissociation in organic solar cells (OSCs) without significant loss of open-circuit voltage. However, this strategy tends to promote F\"orster resonance energy transfer (FRET) from the donor to the acceptor (D-A), a consequence generally ignored until recently. In spite of the advances reported on this topic, the correlation between charge-transfer (CT) state binding energy and driving force remains unclear, especially in the presence of D-A FRET. To address this question, we employ a kinetic approach to model the charge separation in ten different D/A blends using non-fullerene acceptors. The model considers the influence of FRET on photoluminescence (PL) quenching efficiency. It successfully predicts the measured PL quenching efficiency for D or A photoexcitation in those blends, including the ones for which the D-A FRET process is relevant. Furthermore, the application of the model allows to quantifying the fractions of quenching loss associated with charge transfer and energy transfer. Fundamental relationships that controls the exciton dissociation was derived evidencing the key roles played by the Marcus inverted regime, exciton lifetime and mainly by the correlation between the driving force and binding energy of CT state. Based on those findings, we propose some strategies to maximize the quenching efficiency and minimize energy loss of OSCs in the presence of D-A FRET.Comment: 44 pages, 10 figures, 3 table

Improved Performance of Organic Light-Emitting Transistors Enabled by Polyurethane Gate Dielectric

Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that combine in a single structure the advantages of organic light emitting diodes (OLEDs) and organic field-effect transistors (OFETs). However, low charge mobility and high threshold voltage are critical hurdles to practical OLETs implementation. This work reports on the improvements obtained by using polyurethane films as dielectric layer material in place of the standard poly(methylmethacrylate) (PMMA) in OLET devices. It was found that polyurethane drastically reduces the number of traps in the device thereby improving electrical and optoelectronic device parameters. In addition, a model was developed to rationalize an anomalous behavior at the pinch-off voltage. Our findings represent a step forward to overcome the limiting factors of OLETs that prevent their use in commercial electronics by providing a simple route for low-bias device operation.Comment: 25 pages, 5 figures, 1 tabl

A complete year of urology residency training under COVID-19: impact on education and health

ABSTRACT Objectives: To evaluate the impact of COVID-19 pandemics on clinical and surgical practice, educational activities, health and lifestyle behavior of Brazilian urology residents after 1 year of socio-economic restrictions. Materials and Methods: An electronic survey was e-mailed to all postgraduate (PG) students registered by the Brazilian Society of Urology. The survey included an assessment of socio-demographic, clinical practice, educational, health-related and behavior parameters. We also evaluated which subareas of urology were predominantly affected. A similar survey was adapted and sent to the directors of all urology residency programs. Results: COVID-19 pandemic has severely impacted the clinical, surgical, and educational activities of urology residents in Brazil. Urology residents reported >50% decrease in multiple surgical modalities. We highlight kidney transplantation surgeries (66.2%), minor surgeries (62.3%), endoscopic surgeries (42.6%) and reconstructive surgeries (38.8%). This could represent a critical skills gap that residents may face beyond the COVID-19 pandemic. Furthermore, PG students faced stressful situations that caused worsening of mental and physical health, such as getting redirected to assistance of COVID-19 patients (66.9%), and high rate of infection by SARS-CoV-2 (58.2%). Conclusions: The COVID-19 pandemic has severely impacted the clinical, surgical, and educational activities of urology residents in Brazil. This could represent a critical skills gap that residents may face beyond the COVID-19 pandemic. PG students faced stressful situations that caused worsening of mental and physical health such as redirection to assistance of COVID-19 patients, concern about their own contamination and of family members

Dianthracenylazatrioxa[8]circulene: synthesis, characterization and application in OLEDs

A soluble, green-blue fluorescent, pi-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding pi-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm(2) V-1 s(-1). The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m(-2) and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.Peer reviewe

O COTIDIANO E A HISTÓRIA: CONSTRUINDO NOVOS OLHARES NA ADMINISTRAÇÃO

The purpose of this article is to discuss the possible contributions of studies that combine history and everyday life to build new perspectives about Management. To achieve this goal, we discuss the association of Management, history, and studies about everyday life as an option to produce alternative perspectives within Management. We conclude by reiterating that the construction of these dialogues can open interesting paths to the development of self-reflective knowledge that are politically, socially, and geographically positioned