1,328 research outputs found

    Effects of Axial and Centrifugal Forces on the Stability of Liquid Bridges

    Full text link
    The equilibrium and stability equations for liquid bridges are well known, but they are nonlinear and it is difficult to guess real behavior, such as the sensitivity of the shape to axial and rotational forces (measured by Bond and Weber numbers, respectively) or to the geometry of the solid supports that support the bridge. A parametric study by numerical methods of the different effects and the analytical solutions at the bifurcation points in the stability diagrams is presented. The well known shooting method to numerically compute equilibrium shapes of liquid bridges, and their stability limits, is applied to a five parameter case, when different disc sizes (measured by H), bridge lengths (Lr), liquid volumes (Vr), residual axial acceleration (Bo), and solid body centrifugation (We) are contemplated. The bundle of diagrams presented give an idea of the complexities of such a multiparametric analysis and may help in further research to delimitate other forms of instability. The numerical results were used to check the validity of several analytical asymptotic expressions, with perfect agreement over the range of interest (long liquid bridges), but these models only take into consideration the subset (Lr, Vr = 1, H = 0, Bo, We) of the five parameter family. These results will be of great help to plan future space experiments on liquid columns and floating zones in space and in particular will show a method to easily measure very weak residual forces in microgravity platforms

    Introgression of Aegilops triuncialis into Triticum aestivum. A progress report.

    Get PDF
    A. Delibes, I. López-Braña, M. Mena y F. García-Olmedo. 1988. Introgression of Aegüops triuncialis into Triticum aestivum. A progress report. An. Aula Dei 19 (1-2): 189-194. The wild grass Aegüops triuncialis (genomes CCUU) has been crossed with the tetraploid wheat Triticum turgidum (AABB) and the resulting ABCU sterile hybrid has been rescued with pollen from the hexaploid T. aestivum (AABBDD). Seven spikes from two hybrid plants were pollinated with pollen from T. aestivum cv. Almatense and 8 kernels were obtained. After five rounds of selfing, plants with 28 to 41 chromosomes have been derived. Low fertility (3-5 viable kernels per plant) was observed throughout the process. Further crosses to T. aestivum will be performed to obtain stable lines that will be screened for Ae. triuncialis genetic material with the aid of previously identified biochemical chromosome markers and specially developed DNA probes

    Present progress in the characterization of Triticum aestivum/Aegilops ventricosa transfer lines

    Get PDF
    In the laboratory of M. Metzlaff, genome specific DNA probes from Hordeum vulgare were cloned and characterized by H. Junghans. Regarding repeated DNA sequences our further investigations will concéntrate on the proofof alien chromatin in the wheat -Ae. markgrafii crossing material and on the enlargement of the investigation to their distribution in Poaceae species

    Memory and intelligence : Interdependence according to processes and content of tasks

    Get PDF
    Este trabajo procura analizar las características de los factores específicos de la memoria (procesos o contenidos) asociados a Gsm del modelo CHC. Para esto, a una muestra de estudiantes universitarios se le administraron tareas de memoria con diferentes contenidos, varios tests de aptitudes y una prueba de inteligencia general. Se evaluaron dos modelos que relacionan la aptitud general Gsm, bien con la memoria de trabajo y la amplitud de memoria, bien con aptitudes verbales-numéricas y viso-espaciales. Los resultados muestran, para ambos modelos, buenos índices de ajuste, sin embargo, se encontraron datos de regresión estandarizados con una regresión positiva superior entre Gsm y memoria de trabajo y entre Gsm y contenido viso-espacial. También se debe destacar que en ambos modelos se observaron valores de regresión estandarizados de 0.54 y 0.73 entre Gsm y el factor g. Teniendo en cuenta los resultados obtenidos, se discuten algunas implicaciones del estudio para comprender la relación entre inteligencia y memoria.This study investigates the characteristics of the specific memory factors (processes and content) that are associated to the Gsm from the CHC model. Memory tasks with different content, including various aptitude tests and a general intelligence test, were administered to a sample of university students. Two models that relate the general Gsm aptitude, with working memory and memory span, and with verbal-numerical and visual-spatial aptitudes were tested. Results indicate good fit indices for both models tested, as well as evidence for a positive regression between Gsm and working memory and between Gsm and visuospatial content. In both models we observed standardized regression of 0.54 and of 0.73 between Gsm and factor g. Implications for the understanding of the relation between memory and intelligence are discussed.Fundação para a Ciência e a Tecnologia (FCT

    Competencias matemáticas y profesionales de los maestros

    Get PDF
    En esta comunicación describimos el proceso de estudio y puesta en común de un listado de competencias profesionales que sirven como directrices de nuestros cursos de formación de maestros de Educación Primaria, siempre desde el área de Matemáticas. Para esta descripción comenzamos por analizar la evolución reciente de la titulación de maestro en España, hasta establecer la idea de competencia. A continuación, examinamos la noción de competencia, distinguiéndola de la competencia matemática. Posteriormente describimos el trabajo realizado por los profesores del Departamento de Didáctica de la Matemática de la Universidad de Granada, para establecer un listado de las competencias que van a guiar la enseñanza de las asignaturas que impartimos dentro de la titulación de Maestro especialidad Educación Primaria

    The role of Spartina maritima and Sarcocornia fruticosa on trace metals retention in Ria Formosa, Portugal

    Get PDF
    Over the last years, phytoremediation has become an increasingly recognized pathway for contaminant removal from water and shallow soils. Assessing the phytoremediation potential of wetlands is complex due to variable conditions of hydrology, soil/sediment types, plant species diversity, growing season and water chemistry. Physico-chemical properties of wetlands provide many positive attributes for remediating contaminants. Saltmarsh plants can sequestrate and inherently tolerate high metal concentrations found in saltmarsh sediments

    Rapid decrease in titer and breadth of neutralizing anti-HCV antibodies in HIV/HCV-coinfected patients who achieved SVR

    Get PDF
    The main targets for neutralizing anti-hepatitis C virus (HCV) antibodies (HCV-nAbs) are the E1 and E2 envelope glycoproteins. We have studied the characteristics of HCV-nAbs through a retrospective study involving 29 HIV/HCV-coinfected patients who achieved sustained virological response (SVR) with pegIFNα+ribavirin anti-HCV therapy. Plasma samples at baseline and week 24 after SVR were used to perform neutralization assays against fve JFH1-based HCV recombinant viruses coding for E1 and E2 from genotypes 1a (H77), 1b (J4), 2a (JFH1), 3a (S52) and 4a (ED43). At baseline, the majority of plasma samples neutralized 1a, 1b, 2a, and 4a, but not 3a, genotypes. Twenty-four weeks following SVR, most neutralizing titers declined substantially. Furthermore, titers against 3a and 2a were not detected in many patients. Plasma samples with high HCV-nAb titers neutralized all genotypes, and the highest titers at the starting point correlated with the highest titers at week 24 after SVR. In conclusion, high titers of broad-spectrum HCV-nAbs were detected in HIV/HCV-coinfected individuals, however, those titers declined soon after SVRThis study was supported by grants from Instituto de Salud Carlos III (ISCIII; grant numbers PI14/01094 and PI17/00657 to JB, PI17/00903 to JGG, PI14CIII/00011 and PI17CIII/00003 to SR) and Ministerio de Sanidad, Servicios Sociales e Igualdad (grant number EC11-241). Te study was also funded by the RD16CIII/0002/0002, RD16/0025/0018, and RD16/0025/0017 projects as part of the Plan Nacional R+D+I and co-funded by ISCIII- Subdirección General de Evaluación and the Fondo Europeo de Desarrollo Regional (FEDER

    Experience with the use of Rituximab for the treatment of rheumatoid arthritis in a tertiary Hospital in Spain: RITAR study

    Full text link
    There is evidence supporting that there are no relevant clinical differences between dosing rituximab 1000 mg or 2000 mg per cycle in rheumatoid arthritis (RA) patients in clinical trials, and low-dose cycles seem to have a better safety profile. Our objective was to describe the pattern of use of rituximab in real-life practice conditions. Methods: Rituximab for RA in clinical practice (RITAR) study is a retrospective cohort study from 2005 to 2015. Eligibility criteria were RA adults treated with rituximab for active articular disease. Response duration was the main outcome defined as months elapsed from the date of rituximab first infusion to the date of flare. A multivariable analysis was performed to determine the variables associated with response duration. Results: A total of 114 patients and 409 cycles were described, 93.0% seropositive and 80.7% women. Rituximab was mainly used as second-line biological therapy. On demand retreatment was used in 94.6% of cases versus fixed 6 months retreatment in 5.4%. Median response duration to on demand rituximab cycles was 10 months (interquartile range, 7–13). Multivariable analysis showed that age older than 65 years, number of rituximab cycles, seropositivity, and first- or second-line therapy were associated with longer response duration. The dose administered at each cycle was not significantly associated with response duration. Conclusions: Our experience suggests that 1000 mg rituximab single infusion on demand is a reasonable schedule for long-term treatment of those patients with good response after the first cycles, especially in seropositive patients and when it is applied as a first- or second-line biological therap

    Atividade de extratos vegetais in vitro sobre ovos de nematóides gastrintestinais de ovinos.

    Get PDF
    Atualmente o uso indiscriminado de antiparasitários na ovinocultura se tornou rotina na maioria das propriedades e existe uma preocupação com relação aos resíduos dessas drogas nos produtos de origem animal e no ambiente. Além disto, a necessidade de se encontrar novos princípios ativos faz com que pesquisas com fitoterápicos se tornem cada vez mais freqüentes e assumam um caráter científico mais rigoroso. Esse estudo teve por objetivo avaliar a ação ovicida de extratos vegetais brutos sobre nematóides gastrintestinais de ovinos. Realizou-se testes in vitro por meio de metodologia padronizada de inibição de eclodibilidade. Foram avaliadas as seguintes espécies vegetais: extrato hidrometanólico das cascas do fruto (20 mg) e da semente (22 mg) de Trichilia elegans e partição metanólica das folhas de Euxylophora paraensis (20 mg). Os extratos foram produzidos no Departamento de Química da Universidade Federal de São Carlos e os testes foram realizados de acordo com a disponibilidade dos parasitas no Laboratório de Sanidade Animal da Embrapa Pecuária Sudeste (São Carlos, SP). Os ovos foram recuperados de fezes contaminadas por meio do uso seqüencial de peneiras e foram incubados (cerca de 100 ovos/poço) com os extratos em placas de 24 poços em B.O.D. a 25°C por 72 horas, quando foi realizada a contagem das larvas eclodidas. Os extratos tiveram seus solventes evaporados e depois testados a 100%, 50% e 25% da massa inicial, adicionando-se água destilada. Foram feitas três repetições e o controle contendo água destilada. Os extratos não apresentaram ação ovicida nas concentrações testadas, exceto o extrato hidrometanólico das cascas do fruto T. elegans a 100%. Enquanto no controle ocorreu eclodibilidade de 88,2% das larvas, neste tratamento a eclodibilidade foi de 21,5%, indicado a possibilidade de seu uso no controle desses parasitas
    corecore