3 research outputs found
The structure of Chariklo's rings from stellar occultations
Two narrow and dense rings (called C1R and C2R) were discovered around the
Centaur object (10199) Chariklo during a stellar occultation observed on 2013
June 3. Following this discovery, we planned observations of several
occultations by Chariklo's system in order to better characterize the physical
properties of the ring and main body. Here, we use 12 successful occulations by
Chariklo observed between 2014 and 2016. They provide ring profiles (physical
width, opacity, edge structure) and constraints on the radii and pole position.
Our new observations are currently consistent with the circular ring solution
and pole position, to within the km formal uncertainty for the ring
radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal
significant width variations from to 7.5 km. The width of the fainter
ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and
outer edges of C1R are consistent with infinitely sharp boundaries, with
typical upper limits of one kilometer for the transition zone between the ring
and empty space. No constraint on the sharpness of C2R's edges is available. A
1 upper limit of m is derived for the equivalent width of
narrow (physical width <4 km) rings up to distances of 12,000 km, counted in
the ring plane
Pre-clinical lung squamous cell carcinoma mouse models to identify novel biomarkers and therapeutic interventions
Primary lung carcinoma or lung cancer (LC) is classified into small-cell or non-small-cell (NSCLC) lung carcinoma. Lung squamous cell carcinoma (LSCC) is the second most common subtype of NSCLC responsible for 30% of all LCs, and its survival remains low with only 24% of patients living for five years or longer post-diagnosis primarily due to the advanced stage of tumors at the time of diagnosis. The pathogenesis of LSCC is still poorly understood and has hampered the development of effective diagnostics and therapies. This review highlights the known risk factors, genetic and epigenetic alterations, miRNA biomarkers linked to the development and diagnosis of LSCC and the lack of therapeutic strategies to target specifically LSCC. We will also discuss existing animal models of LSCC including carcinogen induced, transgenic and xenograft mouse models, and their advantages and limitations along with the chemopreventive studies and molecular studies conducted using them. The importance of developing new and improved mouse models will also be discussed that will provide further insights into the initiation and progression of LSCC, and enable the identification of new biomarkers and therapeutic targets
Exposição ao mercúrio e ao arsênio em Estados da Amazônia: sÃntese dos estudos do Instituto Evandro Chagas/FUNASA Exposure to mercury and arsenic in Amazon States: a summary of studies by the Evandro Chagas Institute/FUNASA
Este artigo é uma revisão das pesquisas da Seção de Meio Ambiente do Instituto Evandro Chagas/FUNASA sobre exposição ao mercúrio (Hg) no vale do rio Tapajós e Estado do Acre, e exposição ao arsênio (As) através de resÃduos da exploração de manganês (Mn) realizada pela ICOMI deixados no Porto de Santana-AP. Em relação ao mercúrio, têm sido pesquisadas populações sob risco através da via respiratória ou alimentar. No primeiro caso, os trabalhadores de casas de compra e venda de ouro têm apresentado teores mais elevados de Hg em urina do que os garimpeiros estudados. No segundo caso, as populações ribeirinhas têm mostrado nÃveis diferenciados de exposição (Hg em cabelo). Comunidades ribeirinhas situadas em áreas não afetadas pelo mercúrio da garimpagem e com hábitos alimentares semelhantes à s de área de risco têm sido avaliadas, visando a construção de parâmetros de normalidade regional. São também pesquisados os teores de Hg em materiais ambientais e na biota aquática. Os estudos de saúde humana e ambiente na cidade de Santana-AP objetivaram avaliar as fontes e possÃveis vias de exposição da população da comunidade do Elesbão ao arsênio. Verificou-se a existência de fonte de risco através dos rejeitos de Mn, porém os nÃveis de As na água consumida pela população mostraram-se dentro dos parâmetros de normalidade. As médias encontradas em sangue e cabelo coincidem com médias de normalidade referidas na literatura, em populações não expostas, e as associações entre variáveis epidemiológicas, avaliação clÃnico-laboratorial e os teores de arsênio não mostraram significância estatÃstica.<br>This article is a review of the studies carried out by Environmental Section of the Evandro Chagas Institute/FUNASA on mercury (Hg) exposure in the Tapajós river basin, and arsenic exposure (As) due to residues of the manganese (Mn) exploration, performed by ICOMI and left at the port of Santana-AP. Regarding mercury exposure, the populations under respiratory or ingestion risk have been studied. In the first case, gold shop workers have been showing higher Hg levels in urine than gold miners. In the second case, riverine populations have been showing differentiated exposure levels (Hg in hair). Riverine communities from areas not affected by gold mining mercury and with similar dietary habits to those of a risk area are studied seeking to establish what the normal parameters for the region area. Levels of Hg in environmental materials and in the aquatic biota were also studied. The studies of human and environmental health in the city of Santana-AP were carried out to evaluate sources and possible exposure routes of the Elesbão community to Arsenic. The existence of a risk source for As was verified through Mn wastes, although the As levels in the water consumed by the population were within normal standards. The averages found in blood and hair match normal averages found in the literature in non-exposed population, and the statistical associations between epidemiological variables, clinical evaluation, laboratorial results and arsenic levels were not significant