171,253 research outputs found
Repeated evolution of underwater rebreathing in diving Anolis lizards
No full textThis repository contains all data used to generate all non-image figures (Figures 2-4, Supplementary figures) in Boccia et al 2021, "Repeated evolution of underwater rebreathing in diving Anolis lizards". Data are divided into behavioural and oxygen trace folders. Please see https://github.com/chrisboccia/anole-rebreathing-curbio for code and the data processing pipeline used.
Authors: Christopher K. Boccia, Lindsey Swierk, Fernando P. Ayala-Varela, James Boccia, Isabela L. Borges, Camilo Andres Estupiñán, Alexandra M. Martin, Ramón E. Martínez-Grimaldo, Sebastian Ovalle, Shreeram Senthivasan, Ken S. Toyama, María del Rosario Castañeda, Andrés García, Richard E. Glor, D. Luke Mahler
Abstract: Air-based respiration limits the use of aquatic environments by ancestrally terrestrial animals. To overcome this challenge, diving arthropods have evolved to respire without resurfacing using air held between their cuticle and surrounding water. Inspired by natural history observations in Haiti (DLM & REG pers. obs.) and Costa Rica, we conducted experiments documenting routine air-based underwater respiration in several distantly-related semi-aquatic Anolis lizard species. Semi-aquatic anoles live along neotropical streams and frequently dive for refuge or food, remaining underwater for up to 18 minutes. While submerged, these lizards iteratively expire and re-inspire narial air bubbles – underwater “rebreathing.” Rebreathed air is used in respiration, as the partial pressure of oxygen in the bubbles decreases with experimental submersion time in living anoles but not in mechanical controls. Non-aquatic anoles occasionally rebreathe when submerged but exhibit more rudimentary rebreathing behaviors. Anole rebreathing is facilitated by a thin air layer (i.e., a “plastron”, sensu Brocher) supported by the animal’s rugose skin upon submergence. We suggest that hydrophobic skin, which we observed in all sampled anoles, may have been exaptative, facilitating the repeated evolution of specialized rebreathing in species that regularly dive. Phylogenetic analyses strongly suggest that specialized rebreathing is adaptive for semi-aquatic habitat specialists. Air-based rebreathing may enhance dive performance by incorporating dead space air from the buccal cavity or plastron into the lungs, facilitating clearance of carbon dioxide, or allowing uptake of oxygen from surrounding water (i.e., a “physical gill” mechanism)
Epidemiology of cancer and principles of prevention
No full textNeoplasms include several hundreds of diseases, which can be distinguished by localization, morphology, clinical behaviour and response to therapy. The number of new cases of cancer which occurred worldwide in 2008 has been estimated at about 12,700,000. Of these, 6,600,000 occurred in men and 6,000,000 in women. About 5,600,000 cases occurred in high-income countries (North America, Japan, Europe including Russia, Australia and New Zealand) and 7,100,000 in low- and middle-income countries. Among men, lung, stomach, colorectal, prostate and liver cancer s are the most common malignant neoplasms, while breast, colorectal, cervical, lung and stomach are the most common neoplasms among women. Analytical studies have shown the causal role of several exposures in the aetiology of malignant neoplasms: The major causes of human cancer are tobacco smoking, dietary factors, obesity, alcohol drinking, infectious agents, occupation and pollution, reproductive factors and exogenous hormones, perinatal and growth factors, ionizing and nonionizing radiations, medical procedures and drugs, besides genetic factors. Consequently, the prevention of cancer includes primary and secondary prevention programmes. The main goal of primary prevention is to reduce the incidence of cancer through the reduction of exposure to risk factors for cancer at the population level, while secondary prevention takes place through the early detection of cancer. Where feasible, primary prevention programmes are largely cost-effective, i.e. the reduction of the burden of disease is achieved with a reasonable money investment, while this is not always the case for secondary prevention programmes. In this chapter, we aim to describe the current burden of cancer and the main health policies available, in order to provide key elements for public health professionals
Oral contraceptives, human papillomavirus and cervical cancer
No full textOncogenic human papillomavirus is the key determinant of cervical cancer, but other risk factors interact with it to define individual risk. Among these, there is oral contraceptive (OC) use. A quantitative review of the link between OCs and cervical cancer was performed. Long-term (>5 year) current or recent OC use has been related to an about two-fold excess risk of cervical cancer. Such an excess risk, however, levels off after stopping use, and approaches unity 10 or more years after stopping. The public health implications of OC use for cervical cancer are limited. In any case, such implications are greater in middle-income and low-income countries, as well as in central and eastern Europe and Latin America, where cervical cancer screening and control remain inadequate
Gender Participation and Performance in Boccia International-Level Events
No full textBackground/Objectives: Boccia is an attractive and growing adapted sport. For approximately 30 years, this parasport was played together by male and female athletes, a fact that recently changed, to our best knowledge, without scientific support. Hence, this study aimed to analyse the relationship between gender participation and performance in Boccia international-level events. Methods: For data collection, four specific international-level Boccia events between 2012 and 2018 were selected as partials were available in the official competition websites (2708 partials, which represent a total of 32,496 ball throws). Results: We found that partials won by male athletes systematically increased between 2012 and 2018 but tended to stabilize between 2017 and 2018, contrary to females, with a growing trend from 2016 onwards. No differences were observed, considering the players’ gender and the type of partials (adjusted, balanced, and unbalanced) in the Boccia classes BC1, BC2, and BC3. In BC4 differences were found, but with little variance or low association level (Cramer’s Phi coefficient of 0.114). Conclusions: The results emphasize that based on performance, both men and woman can play Boccia together. Although, if the focus of separating genders in Boccia is toward growing and effective female participation and equal success and reward opportunities, this study highlights as a good perspective aiming regular practice of physical activity, exercise, and sport in people with disabilities, promoting their quality of life
Epidemiology, Biostatistics and Public Health, EBPH: a new vision for two old journals
No full textThe launch of this new journal, Epidemiology, Biostatistics and Public Health (EBPH), enables us to embrace new challenges, and renew our commitment to our readers, our authors and fellow editors, and ultimately to the public health community worldwide
Addition of Hydrocarbons to H-Si(100) in Extra-Mild Conditions: A Novel Mechanism Valid for Single and Multiple C-C Bonds
No full textThe establishment of strong C-Si bonds connecting a molecular moiety to the Si surface has been widely reported with different synthetic recipes, but general and reliable reaction mechanisms have not been described yet for the distinct chemical routes. The coupling of a suitable functional group in the molecule with a reactive termination of the Si surface is a prerequisite for the reaction to happen, and the presence of a C-C multiple bond has long been thought to be necessary for an extra-mild attachment, as in the visible light induced organics-Si anchoring reaction. In this paper, the addition of saturated and unsaturated hydrocarbons to the hydrogenated Si(100) surface has been modeled by density functional theory calculations. The aim is to describe a mechanism allowing for the addition of single C-C bonds to Si(100) and the addition of C=C bonds with preservation of the unsaturation. In fact, both these reactions have been observed recently, but they are not explained by radical-initiated hydrosilylation, the more commonly invoked mechanism for this class of processes. The mechanism proposed here is described by computing the reaction path in the ground state and recomputing the energies in the first excited state. Both for saturated hydrocarbons and for unsaturated hydrocarbons we found that the activation barriers in the excited state reduce to about 60-65% of their ground state value. The barrier lowering is explained in terms of the frontier orbital change along the reaction path. These findings can explain why visible light can activate the formation of a C-Si bond, even if it is not energetic enough to break a H-Si bond
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