1,235 research outputs found

    Vibration propagation in discrete element particle models of rock

    Get PDF
    Vibrations in rock masses can be a significant hazard, leading to human discomfort and structural damage. Recent cases of subway excavation or tunnel excavation near existing dams in Portugal have raised again the importance of this topic. Traditional statistical tools have been used to study wave propagation in rock, but fall short when rock fracturing or faulting radically changes the way vibration propagates. Numerical models such as finite-element or finite-difference models also have some insufficiencies, namely in the way discontinuities are represented. We propose the utilization of bonded particle models based on the Particle Discrete Element Method. Synthetic rock samples are generated and their static elastic properties are calibrated by manipulating micro-properties (assembly organization and normal and shear contact stiffness). The static and dynamic properties of the rock cores are tested and the complete elastic response of the model is evaluated and discussed

    Tooth abnormalities in individuals with unilateral alveolar clefts : a comparison between sides using cone-beam computed tomography

    Get PDF
    Background: Tooth abnormalities are most often present in individuals with oral clefts than general population, and lead to a long-term impact on facial anatomy and self-esteem. The purpose of this study was to compare the proportion of dental anomalies between the cleft side and non-cleft side in individuals with non-syndromic unilateral alveolar clefts (AC). Material and Methods: Twenty cone beam computed tomography (CBCT) scans were converted into threedimensional (3D) virtual models. The dental anomalies considered were: tooth agenesis; supernumerary teeth; giroversion; and microdontia. Statistical analysis was performed using the McNemar?s test and Fisher?s exact test ( p < 0.05). Results: Statistically significant differences were not found either between the prevalence of individuals with dental abnormalities on the non-cleft side and the sides of the AC ( p = 1.00), or sex ( p = 0.36). Tooth agenesis was the most prevalent dental anomaly (55.6%). On the cleft side the lateral incisor was tooth most involved by dental anomalies; and the second premolar was the most affected on the non-cleft side. Conclusions: This study showed a high frequency of dental anomalies in the cleft individuals and indicated that the side of AC and sex do not interfere in the proportion of dental anomalies on non-cleft side

    Larval susceptibility of Aedes aegypti and Culex quinquefasciatus populations to chemical insecticides

    Get PDF
    OBJECTIVE: To evaluate the susceptibility to chemical insecticides of Culex quinquefasciatus and Aedes aegypt larvae from areas subjected to control treatments or not. METHODS: Bioassays for diagnostic concentration and multiple concentration were performed for organophosphate and pyrethroid insecticides according to World Health Organization parameters. The susceptibility was assessed for mosquito larvae collected from an area not subjected to chemical control (Campinas, State of São Paulo, SP) and from other areas (Campo Grande, Mato Grosso do Sul, MS, and Cuiabá, Mato Grosso, MT), in Brazil, subjected to such treatments. RESULTS: Tests for Culex quinquefasciatus larvae from Campinas, SP, allowed suspicion of resistance to cypermethrin and gave evidence of resistance to cyfluthrin. Larvae of this species collected in Campo Grande, MS, and Campinas, SP, presented resistance to temephos. For the colony from the latter locality, the following resistance rates were established: RR50=6.36 and RR95=4.94, in relation to a standard susceptible strain. Moreover, tests for Aedes aegypti showed similar susceptibility to temephos for a field population from Cuiabá, MT, and a laboratory population. CONCLUSIONS: The results indicate resistance of Culex quinquefasciatus to organophosphate and pyrethroid insecticides and make evident the need for evaluation and monitoring of the efficiency of insecticides to be used in mosquito control programs.OBJETIVO: Avaliar a susceptibilidade a inseticidas químicos de larvas de Culex quinquefasciatus e Aedes aegypti, provenientes de áreas sujeitas ou não a tratamentos de controle. MÉTODOS: Foram coletadas larvas de mosquitos em uma área não sujeita a tratamentos com inseticidas (Campinas, SP) e em áreas sujeitas a esses tratamentos (Campo Grande, MS e Cuiabá, MT). Foram usados bioensaios com concentrações diagnóstico e concentrações múltipla de inseticidas organofosforados e piretróides, segundo padrão da Organização Mundial de Saúde, para avaliar a susceptibilidade dessas larvas. RESULTADOS: Ensaios com larvas de Culex quinquefasciatus de Campinas, SP, permitiram a suspeita de resistência à cipermetrina e evidenciaram resistência à ciflutrina. Larvas dessa espécie coletadas em Campo Grande, MS, e Campinas, SP, apresentaram resistência ao temephos. Para a colônia campineira desta espécie, foram estabelecidas as razões de resistência: RR50=6,36 e RR95=4,94, com base em linhagem susceptível padrão. Adicionalmente, os testes com Aedes aegypti mostraram susceptibilidade similar ao temephos em uma população de campo (Cuiabá, MT) e uma de laboratório. CONCLUSÕES: Os resultados indicam resistência a organofosforado e piretróides em Culex quinquefasciatus, evidenciando a necessidade de avaliações e monitoramento da efetividade dos inseticidas a serem usados nos programas de controle de mosquitos

    BRS Mandobi: A New Forage Peanut Cultivar Propagated by Seeds for the Tropics

    Get PDF
    Forage peanut (Arachis pintoi) is a forage legume of relatively recent use in beef and dairy cattle feeding. Although it is native exclusively to Brazil, the first cultivar, Amarillo, was released in Australia in 1987. Forage peanut has a great number of favourable attributes for establishing grass-legume mixtures, which guarantee the persistence and high yields of high quality forage in cultivated pastures. Therefore, studies with this species have intensified in many tropical regions of the world (Assis and Valentim 2009). In the state of Acre, western Brazilian Amazon, 137,000 ha are cultivated with forage peanut, cv. Belmonte, benefiting thousands of producers, with annual economic impact of USD $46 M (Embrapa 2012). Social and environmental impacts resulting from the use of this legume are also highly positive. However, despite the success achieved in mixed pastures with forage peanut, expansion of the area sown has been relatively slow because vegetative propagation using stolons is labour intensive and requires large quantities of limited vegetative material. In Brazil, Embrapa has co-ordinated the development of new forage peanut cultivars and their evaluation in different biomes. The objective of this paper is to present a new cultivar of seed propagated forage peanut, developed for use in tropical regions, by Embrapa in partnership with Unipasto (Association for Promotion of Breeding Research in Tropical Forage)

    3-(2,4-Dibromo­anilino)-2,2-dimethyl-2,3-dihydro­naphtho[1,2-b]furan-4,5-dione: a new substituted aryl­amino nor-β-lapachone derivative

    Get PDF
    The title compound, C20H15Br2NO3, shows the furan ring to adopt a half-chair conformation and the two ring systems to be approximately perpendicular [dihedral angle = 71.0 (2)°]. In the crystal structure, inter­molecular C—H⋯O contacts link the mol­ecules

    Effects of Exercise Training under Hyperbaric Oxygen on Oxidative Stress Markers and Endurance Performance in Young Soccer Players: A Pilot Study

    Get PDF
    The aim of the present study was to determine the effects of three weeks of hyperbaric oxygen (HBO2) training on oxidative stress markers and endurance performance in young soccer players. Participants (18.6±1.6 years) were randomized into hyperbaric-hyperoxic (HH) training (n=6) and normobaric normoxic (NN) training (n=6) groups. Immediately before and after the 5th, 10th, and 15th training sessions, plasma oxidative stress markers (lipid hydroperoxides and uric acid), plasma antioxidant capacity (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid [TROLOX]), arterial blood gases, acid-base balance, bases excess (BE), and blood lactate analyses were performed. Before and after intervention, maximal oxygen uptake (VO2max) and peak power output (PPO) were determined. Neither HH nor NN experienced significant changes on oxidative stress markers or antioxidant capacity during intervention. VO2max and PPO were improved (moderate effect size) after HH training. The results suggest that HBO2 endurance training does not increase oxidative stress markers and improves endurance performance in young soccer players. Our findings warrant future investigation to corroborate that HBO2 endurance training could be a potential training approach for highly competitive young soccer players

    Avaliação antropométrica longitudinal de lactentes nascidos de mães infectadas pelo HIV-1

    Get PDF
    OBJETIVO: Evaluar los parámetros de crecimiento en lactantes nacidos de madres infectadas con el VIH-1. MÉTODOS: Evaluación longitudinal de los z-escores peso-edad (PI), estatura-edad (EI), peso-estatura (PE) fue realizada en una cohorte. Fueran estudiados 97 lactantes no infectados y 33 lactantes infectados nacidos de madres infectadas con el VIH-1 en Belo Horizonte, Sureste de Brasil, de 1995 a 2003. El tiempo medio de seguimiento para los lactantes infectados y no infectados fue de 15,8 meses (variación: 6,8 a 18,0 meses) y 14,3 meses (variación: 6,3 a 18,6 meses), respectivamente. Se utilizó el modelo de regresión linear de efectos mixtos ajustado por máxima verosimilitud restringida para construir las curvas de crecimiento. RESULTADOS: Los z-escores PI, EI y PE de los lactantes infectados con el VIH-1 presentaron decrecimiento. A los seis meses, la diferencia promedio en los z-escores PI, EI y PE entre lactantes infectados y no infectados con el VIH era, respectivamente, 1,02, 0,59 y 0,63 desviaciones-estándares. A los 12 meses, la diferencia promedio en los z-escores PI, EI y PE entre lactantes infectados y no infectados era, respectivamente, 1,15, 1,01 y 0,87 desviaciones-estándares. CONCLUSIONES: El comprometimiento precoz y creciente de los indicadores antropométricos de niños infectados con el VIH-1 muestra la importancia de identificar precozmente niños infectados con el VIH que están en riesgo nutricional y la necesidad de evaluarse continuamente las intervenciones nutricionales adoptadas.OBJECTIVE: To evaluate the growth parameters in infants who were born to HIV-1-infected mothers. METHODS: The study was a longitudinal evaluation of the z-scores for the weight-for-age (WAZ), weight-for-length (WLZ) and length-for-age (LAZ) data collected from a cohort. A total of 97 non-infected and 33 HIV-infected infants born to HIV-1-infected mothers in Belo Horizonte, Southeastern Brazil, between 1995 and 2003 was studied. The average follow-up period for the infected and non-infected children was 15.8 months (variation: 6.8 to 18.0 months) and 14.3 months (variation: 6.3 to 18.6 months), respectively. A mixed-effects linear regression model was used and was fitted using a restricted maximum likelihood. RESULTS: There was an observed decrease over time in the WAZ, LAZ and WLZ among the infected infants. At six months of age, the mean differences in the WAZ, LAZ and WLZ between the HIV-infected and non-infected infants were 1.02, 0.59, and 0.63 standard deviations, respectively. At 12 months, the mean differences in the WAZ, LAZ and WLZ between the HIV-infected and non-infected infants were 1.15, 1.01, and 0.87 standard deviations, respectively. CONCLUSIONS: The precocious and increasing deterioration of the HIV-infected infants' anthropometric indicators demonstrates the importance of the early identification of HIV-infected infants who are at nutritional risk and the importance of the continuous assessment of nutritional interventions for these infants.OBJETIVO: Avaliar os parâmetros de crescimento em lactentes nascidos de mães infectadas com o HIV-1. MÉTODOS: Avaliação longitudinal dos z-escores peso-idade (PI), estatura-idade (EI), peso-estatura (PE) foi realizada em uma coorte. Foram estudados 97 lactentes não-infectados e 33 lactentes infectados nascidos de mães infectadas com o HIV-1 em Belo Horizonte, MG, de 1995 a 2003. O tempo mediano de seguimento para os lactentes infectados e não-infectados foi de 15,8 meses (variação: 6,8 a 18,0 meses) e 14,3 meses (variação: 6,3 a 18,6 meses), respectivamente. Utilizou-se o modelo de regressão linear de efeitos mistos ajustado por máxima verossimilhança restrita para construir as curvas de crescimento. RESULTADOS: Os z-escores PI, EI e PE dos lactentes infectados com o HIV-1 apresentaram decréscimo. Aos seis meses, a diferença média nos z-escores PI, EI e PE entre lactentes infectados e não-infectados com o HIV era, respectivamente, 1,02, 0,59 e 0,63 desvios-padrão. Aos 12 meses, a diferença média nos z-escores PI, EI e PE entre lactentes infectados e não-infectados era, respectivamente, 1,15, 1,01 e 0,87 desvios-padrão. CONCLUSÕES: O comprometimento precoce e crescente dos indicadores antropométricos de crianças infectadas com o HIV-1 mostra a importância de identificar precocemente crianças infectadas com o HIV que estão em risco nutricional e a necessidade de se avaliarem continuamente as intervenções nutricionais adotadas
    • …
    corecore