Navegando por Data de Publicação, começando com "2025-03-14"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 5 de 5

Efeitos do contaminante emergente nonilfenol etoxilado (NPE) em múltiplos biomarcadores em girinos de rã-touro (Aquarana catesbeiana) sob o cenário do aquecimento global
(Universidade Federal de São Carlos, 2025-03-14) Gonçalves, Yan Costa; Monteiro, Diana Amaral; https://lattes.cnpq.br/0358411551730768; https://orcid.org/0000-0002-1178-6673; https://lattes.cnpq.br/4296128053314097; https://orcid.org/0000-0002-2839-0421
The global decline in amphibian populations has been extensively documented and is attributed to a complex interplay of environmental factors. Among these, chemical pollution from emerging contaminants, such as nonylphenol ethoxylate (NPE), combined with the increase in surface water temperatures due to climate change, stands out. These factors, acting synergistically, may exacerbate the significant decline in amphibian species. NPE, a surfactant widely used in the formulation of sanitary products, has frequently been detected in Brazilian aquatic ecosystems at alarming concentrations, exceeding international regulations. Despite its environmental relevance, there is a gap in knowledge regarding the sublethal effects of NPE on amphibians, particularly under thermal stress conditions. This study aimed to investigate the sublethal effects of acute exposure (48 h) to an environmentally relevant concentration of NPE (30 µg L-1) on Aquarana catesbeiana tadpoles at Gosner stage 25, under two distinct thermal conditions (25°C and 30°C), as well as to evaluate the interaction between these factors (NPE × temperature). Multiple biomarkers were analyzed: biometric indices (Fulton’s condition factor [K], hepatosomatic index [HSI], and relative ventricular mass [RVM]), physiological biomarkers (heart rate [fH], ventricular contraction force [Fc], cardiac pumping capacity [CPC], contraction rate [+dF/dt], and relaxation rate [-dF/dt]), biochemical biomarkers (activity of the antioxidant enzymes superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and glutathione peroxidase [GPx]; reduced glutathione content [GSH]; levels of lipid peroxidation [LPO] and protein carbonylation [PC] in hepatic, branchial, and muscular tissues), and neurotoxic biomarkers (acetylcholinesterase [AChE] activity in the brain and muscle). Exposure to NPE induced hepatotoxic effects (reduction in HSI and antioxidant defenses), cardiotoxic effects (reductions in RVM, Fc, +dF/dt, and -dF/dt), tachycardia, alterations in the antioxidant defense system, and oxidative stress in the gills and muscle, as well as inhibition of muscular AChE. The increase in temperature intensified the negative inotropic effect, depleted branchial antioxidant defenses, and exacerbated oxidative stress in the liver and muscle, in addition to causing central neurotoxicity. These results indicate that in environments contaminated with NPE, rising temperatures associated with climate change may aggravate the sublethal effects of NPE, even after short-term exposure. The absence of regulations for safe NPE concentrations in Brazilian legislation, coupled with global warming, represents a critical threat to biodiversity, particularly for amphibians, highlighting the urgent need for environmental guidelines and mitigation strategies.
Trivialidade topológica relativa de família de funções
(Universidade Federal de São Carlos, 2025-03-14) Figueira, Vitor de Moraes; Tomazella, João Nivaldo; https://lattes.cnpq.br/0051564735964760; https://orcid.org/0000-0003-2500-0886; https://lattes.cnpq.br/6307066011187330; https://orcid.org/0009-0002-1593-9793
In this work, we investigate the C^0-\mathcal{R}_X-triviality of families of germs h : (\mathbb{C}^n \times \mathbb{C}, 0) \to (\mathbb{C}, 0), extending the classical \mathcal{R}-equivalence to the context of the group \mathcal{R}_X, which preserves an analytic subvariety (X,0). We analyze sufficient conditions for topological triviality based on the integral closure of the tangent space to the group \mathcal{R}_X, with a particular focus on deformations in quasi-homogeneous varieties. We also study the constancy of the Bruce-Roberts number, \mu_{BR}, in families of functions with isolated singularities.
Efeitos do contaminante emergente nonilfenol etoxilado (NPE) em múltiplos biomarcadores em girinos de rã-touro (Aquarana catesbeiana) sob o cenário do aquecimento global
(Universidade Federal de São Carlos, 2025-03-14) Gonçalves, Yan Costa; Monteiro, Diana Amaral; https://lattes.cnpq.br/0358411551730768; https://orcid.org/0000-0002-1178-6673; https://lattes.cnpq.br/4296128053314097; https://orcid.org/0000-0002-2839-0421
The global decline in amphibian populations has been extensively documented and is attributed to a complex interplay of environmental factors. Among these, chemical pollution from emerging contaminants, such as nonylphenol ethoxylate (NPE), combined with the increase in surface water temperatures due to climate change, stands out. These factors, acting synergistically, may exacerbate the significant decline in amphibian species. NPE, a surfactant widely used in the formulation of sanitary, hygienic and agrochemical products, has frequently been detected in Brazilian aquatic ecosystems at alarming concentrations, exceeding international regulations. Despite its environmental relevance, there is a gap in knowledge regarding the sublethal effects of NPE on amphibians, particularly under thermal stress conditions. This study aimed to investigate the sublethal effects of acute exposure (48 h) to an environmentally relevant concentration of NPE (30 µg L-1) on Aquarana catesbeiana tadpoles at Gosner stage 25, under two distinct thermal conditions (25°C and 30°C), as well as to evaluate the interaction between these factors (NPE × temperature). Multiple biomarkers were analyzed: biometric indices (Fulton’s condition factor [K], hepatosomatic index [HSI], and relative ventricular mass [RVM]), physiological biomarkers (heart rate [fH], ventricular contraction force [Fc], cardiac pumping capacity [CPC], contraction rate [+dF/dt], and relaxation rate [-dF/dt]), biochemical biomarkers (activity of the antioxidant enzymes superoxide dismutase [SOD], catalase [CAT], glutathione S-transferase [GST], and glutathione peroxidase [GPx]; reduced glutathione content [GSH]; levels of lipid peroxidation [LPO] and protein carbonylation [PC] in hepatic, branchial, and muscular tissues), and neurotoxic biomarkers (acetylcholinesterase [AChE] activity in the brain and muscle). Exposure to NPE induced hepatotoxic effects (reduction in HSI and antioxidant defenses), cardiotoxic effects (reductions in RVM, Fc, +dF/dt, and -dF/dt), tachycardia, alterations in the antioxidant defense system, and oxidative stress in the gills and muscle, as well as inhibition of muscular AChE. The increase in temperature intensified the negative inotropic effect, depleted branchial antioxidant defenses, and exacerbated oxidative stress in the liver and muscle, in addition to causing central neurotoxicity. These results indicate that in environments contaminated with NPE, rising temperatures associated with climate change may aggravate the sublethal effects of NPE, even after short-term exposure. The absence of regulations for safe NPE concentrations in Brazilian legislation, coupled with global warming, represents a critical threat to biodiversity, particularly for amphibians, highlighting the urgent need for environmental guidelines and mitigation strategies.
Métodos de inferência para modelos de regressão aplicados a dados sorológicos de pacientes HIV+ com múltiplos níveis de censura à esquerda
(Universidade Federal de São Carlos, 2025-03-14) Felix, Matheus Henrique; Vieira, Afrânio Márcio Corrêa; https://lattes.cnpq.br/2859528672308405; https://orcid.org/0000-0003-1187-6377; Tomazella, Vera Lucia Damasceno; https://lattes.cnpq.br/8870556978317000; https://orcid.org/0000-0002-6780-2089; https://lattes.cnpq.br/3775653915719529
In this study, the focus is on data that exhibit the occurrence of left-censoring. This type of censoring occurs when the exact time of the event is unknown, but it is known to have occurred before the recorded time. A common example is in the analysis of serological laboratory data, which directly impacts decision-making by physicians, researchers, and other related specialists. Most published studies explore cross-sectional designs, where only one level of censoring is considered. However, occurrences of multiple left-censored measurements at different levels for a single patient are quite common when monitoring a patient's health over time. The same applies to tests conducted in different laboratories, as equipment varies, resulting in different censoring levels. Currently, researchers in the clinical field often exclude such data from their analyses. From a regression perspective, it is essential to adequately model the influence of time, factors, and/or covariates on viral load, as well as the correlation between repeated measurements for the same patient. These aspects are crucial for ensuring reliable statistical inferences, both in clinical trials and in observational cohort or case-control studies. In this context, the objective of this work is to present an appropriate methodology for handling data with multiple levels of left-censoring, particularly assuming Weibull and Log-Normal distributions, applied to real viral load data from HIV-infected patients.
Energias renováveis e mudanças climáticas - Uma jornada de convergências domésticas e internacionais? Análise da promoção da agenda de transição energética no Brasil
(Universidade Federal de São Carlos, 2025-03-14) Picchi, Livia; Vargas, Marcelo Coutinho; https://lattes.cnpq.br/8869018482093008; https://lattes.cnpq.br/0932023056754406
The presente work comprises a comprehensive approach to analyzing the issue os energy, trough a political perspective. The objective is to investigate and map the international and domestic factors that motivated the formulation of public policies to encourage energy generation from renewable sources in Brazil, as well as the actors and arenas, analyzing the influence of international guidelines and international cooperation agréments that deals with renewable energy and mapping the trajectory of policies enacted on the subject by each presidente, in a period rangin from the 1990s to 2016. To this end, two types of sources are used in research, primary and secondary. The list os primary sources will include a study of a oficial documents prepared and made available by the Brazilian State with the Federal Government as its main focus, as well as publications from international organizations, thus prioriziting multi-method analysis, wich includes historical and documents. It is evident that the dissemination of renewable energy as na important tool for guaranteeing energy security in Brazil i salso shaped, according to aspects that consider the opportunity to confront economic and environmental issues, in order to respond to demand inherent to national development and external projection of Brazil as an important “global player” on the international scene, with a focus on energy transition, in a contexto of the rise of international multilateral efforts, especially since the 1990s, to face demands related to climate change. In addition, in terms of results as the domestic level, it is noted that government agenda relating to the sector is quite diverse and that priorities fluctuate considerably over the Years, with periods of adjustments, as well as significant changes depending on each government. It i salso identified that “non-traditional” renewable energies gain prominence in the PT´s governments, while in the Collor, Itamar and Cardoso governments, priorities are focused almost exclusively on water sources. Furthermore, it is argued that between 1990 and 2016 the energy sector had two distinct policy images, one during the Cardoso governments and the others during the PT governments. From this perspective, the set of elements Around two factors, the 2001-2002 energy crisis, and Lula´s election makes the sector´s image change, as well as enabling the processo f diversification of the Brazilian eletrical matriz and the entry of issues relating to renewable energy on the government agenda, both nationally and internationally.