512 research outputs found

    Development and application of a laminar coflow burner for combustion studies at high pressure

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    In the present thesis, it is attempted to build a bridge between the most simplified systems that have already been studied in literature (laminar flame burners, in which simple fuels such as methane, ethane or ethylene are burnt at atmospheric pressure) and the much more complex and demanding environment that is found in practical combustion engines. This is accomplished by designing and constructing a high pressure vessel and laminar burner (HPVB) integrated with an evaporation system. The capability of the HPVB setup of burning vaporized liquid fuels in laminar diffusion and partially premixed flames brings the important opportunity to isolate more easily the impact of fuel chemistry on the combustion behavior of relevant fuels and biofuels. This experimental setup is particularly designed to offer optical accessibility for laser diagnostic techniques, also allowing their assessment and development at elevated pressures. Background information on the type of burners mostly used for combustion studies in laminar flames is given in chapter 2 with focus on measurements in a high pressure environment. A detailed description of the design capabilities of the HPVB setup and the flame stability issues encountered are also presented and discussed. The theory behind the laser diagnostic techniques applied in this work are reviewed in chapter 3. The chapters 4 to 6 present the measurements carried out to characterize a large range of flames from gaseous and vaporized liquid fuels using laser diagnostics. In chapter 7, the heat flux method for laminar burning velocity measurements is presented and a feasibility study is performed to extend the applicability of the method to higher pressures. This is accomplished by integrating the heat flux burner in the high pressure vessel of the HPVB setup. Chapter 8 summarizes the conclusions and provide recommendations

    Evolution and function of CAG/polyglutamine repeats in protein-protein interaction networks

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    Expanded runs of consecutive trinucleotide CAG repeats encoding polyglutamine (polyQ) stretches are observed in the genes of a large number of patients with different genetic diseases such as Huntington's and several Ataxias. Protein aggregation, which is a key feature of most of these diseases, is thought to be triggered by these expanded polyQ sequences in disease-related proteins. However, polyQ tracts are a normal feature of many human proteins, suggesting that they have an important cellular function. To clarify the potential function of polyQ repeats in biological systems, we systematically analyzed available information stored in sequence and protein interaction databases. By integrating genomic, phylogenetic, protein interaction network and functional information, we obtained evidence that polyQ tracts in proteins stabilize protein interactions. This happens most likely through structural changes whereby the polyQ sequence extends a neighboring coiled-coil region to facilitate its interaction with a coiled-coil region in another protein. Alteration of this important biological function due to polyQ expansion results in gain of abnormal interactions, leading to pathological effects like protein aggregation. Our analyses suggest that research on polyQ proteins should shift focus from expanded polyQ proteins into the characterization of the influence of the wild-type polyQ on protein interactions

    Functional and genomic analyses of α-solenoid proteins

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    {alpha}-solenoids are flexible protein structural domains formed by ensembles of alpha-helical repeats (Armadillo and HEAT repeats among others). While homology can be used to detect many of these repeats, some {alpha}-solenoids have very little sequence homology to proteins of known structure and we expect that many remain undetected. We previously developed a method for detection of {alpha}-helical repeats based on a neural network trained on a dataset of protein structures. Here we improved the detection algorithm and updated the training dataset using recently solved structures of {alpha}-solenoids. Unexpectedly, we identified occurrences of {alpha}-solenoids in solved protein structures that escaped attention, for example within the core of the catalytic subunit of PI3KC. Our results expand the current set of known {alpha}-solenoids. Application of our tool to the protein universe allowed us to detect their significant enrichment in proteins interacting with many proteins, confirming that {alpha}-solenoids are generally involved in protein-protein interactions. We then studied the taxonomic distribution of {alpha}-solenoids to discuss an evolutionary scenario for the emergence of this type of domain, speculating that {alpha}-solenoids have emerged in multiple taxa in independent events by convergent evolution. We observe a higher rate of {alpha}-solenoids in eukaryotic genomes and in some prokaryotic families, such as Cyanobacteria and Planctomycetes, which could be associated to increased cellular complexity. The method is available at http://cbdm.mdc-berlin.de/~ard2/

    Antimycobacterial And Cytotoxicity Activities Of Free And Liposome-encapsulated 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4-bromo-phenyl)-n,n- Dimethyl-2-propen-1-amine

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    The antimycobacterial activity of 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4- bromo-phenyl)-N,N-dimethyl-2-propen-1-amine (BBAP), free or incorporated in preformed liposomes, on extracellular M. tuberculosis H37Rv was 8 and 25 μM (MIC), respectively. Extracellular antimycobacterial activity was not significantly improved by entrapment of BBAP in liposomes, but there was a 6.1-fold reduction of BBAP cytotoxicity on J774 macrophages. Liposomal BBAP or its free form showed IC50 values of 165 and 27 μM, resulting in a selectivity index (SI=IC50/MIC) of 3.4 and 6.6, respectively. Free BBAP in concentrations from 10 to 80 μM were quite effective in eliminating intracellular M. tuberculosis while liposomal formulation was less effective at these concentrations.334871874Corbett, E.L., Watt, C.J., Walker, N., Mayer, D.B.M., Willians, B.G., Raviglione, M.C., Dye, C., (2003) Arch. Intern. Med., 163, p. 1009Vynnycky, E., Fine, P.E., (1997) Epidemiol. Infec., 119, p. 183Pandey, R., Khuller, G.K., (2005) J. Antimicrob. Chemother., 55, p. 430De Souza, A.O., Aily D., C.G., Sato, D.N., Durán, N., (1998) J. Antimicrob. Chemother., 42, p. 407De Souza, A.O., Junior, R.R.S., Ferreira-Julio, J.F., Rodriguez, J.A., Melo, P.S., Haun, M., Sato, D.N., Durán, N., (2001) Eur. J. Med. Chem., 36, p. 843De Souza, A.O., Pereira, D.G., Durán, N., (2002) Ann. Rev. Biomed. Sci., 4, p. 53De Souza, A.O., Hemerly, F.P., Busollo, A.C., Melo, P.S., Machado, G.M.C., Miranda, C.C., Santa-Rita, R.M., Durán, N., (2002) J. Antimicrob. Chemother., 50, p. 629De Souza, A.O., Santos, R.R., Sato, D.N., De Azevedo, M.M.M., Ferreira, D.A., Melo, P.S., Haun, M., Durán, N., (2004) J. Braz. Chem. Soc., 15, p. 682De Souza, A.O., Alderete, J.B., Faljoni-Alario, A., Silva, C.L., Durán, N., (2005) J. Chil. Chem. Soc., 50, p. 591De Conti, R., Gimenez, S.M.M., Haun, M., Pilli, R.A., De Castro, S.L., Durán, N., (1996) Eur. J. Med. Chem., 31, p. 915Bangham, A.D., Standish, M.M., Watkins, J.C., (1965) J. Mol. Biol., 13, p. 238Chen, P.S., Toribara, T.Y., Warner, H., (1956) Anal. Chem., 28, p. 1756Oh, Y.K., Nix, D.E., Straubinger, R.M., (1995) Antimicrob. Agents Chemother., 39, p. 2104Collins, L.A., Franzblau, S.G., (1997) Antimicrob. Agents Chemother., 41, p. 1004Denizot, F., Lang, R., (1986) J. Immun. Methods, 89, p. 27

    Association of apolipoprotein E polymorphism with plasma lipids and Alzheimer's disease in a Southern Brazilian population

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    http://www.kulturerbe-digital.de sammelt Informationen zur Digitalisierung

    Changes In Sexual Behavior Following A Sex Education Program In Brazilian Public Schoolsm [mudanças No Comportamento Sexual De Adolescentes De Escolas Públicas No Brasil Após Um Programa De Educação Sexual]

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    This paper describes an evaluation of possible changes in sexual behavior in adolescents who participated in a school-based sex education program in selected public schools in four municipalities in the state of Minas Gerais, Brazil. The program is inserted within the context of reproductive rights, deals with risks involved in unsafe sexual practices and focuses on the positive aspects of sexuality. A quasi-experimental design with pre and post-tests and a non-equivalent control group was used to evaluate the intervention. A total of 4,795 questionnaires were included in this analysis. The program succeeded in more than doubling consistent condom use with casual partners and in increasing the use of modern contraceptives during last intercourse by 68%. The intervention had no effect on age at first intercourse or on adolescents' engagement in sexual activities. The sex education program was effective in generating positive changes in the sexual behavior of adolescents, while not stimulating participation in sexual activities.25511681176(2006) Promoting and Safeguarding the Sexual and Reproductive Health of Adolescents, , World Health Organization, Geneva: World Health Organization, (Policy Brief, 4. Implementing the Global Reproductive Health Strategy)Ross, J., Godeau, E., Dias, S., Sexual health (2004) Young People's Health In Context: Health Behaviour In School-aged Children (hbsc) Study. International Report From the 2001/2002 Survey, pp. 153-60. , In: Currie C, Roberts C, Morgan A, Smith R, Settertobulte W, Samdal O, et al., editors, Copenhagen: WHO Regional Office for Europe, (Health Policy for Children and Adolescents, 4)Kirby, D.B., Laris, B.A., Rolleri, L.A., Sex and HIV education programs: Their impact on sexual behaviors of young people throughout the world (2007) J Adolesc Health, 40, pp. 206-17Figueiró, N.M.D., A produção teórica no Brasil sobre educação sexual (1996) Cad Pesqui, (98), pp. 50-63Figueiró, N.M.D., Revendo a história da educação sexual no Brasil: Ponto de partida para construção de um novo rumo (1998) Nuances, 4, pp. 123-33(1998) Temas Transversais: Orientação Sexual, , Secretaria de Educação Fundamental, Ministério da Educação. Parâmetros curriculares nacionais, Brasília: Secretaria de Educação Fundamental, Ministério da EducaçãoPaiva, V., Pupo, L.R., Barboza, R., O direito à prevenção e os desafios da redução da vulnerabilidade ao HIV no Brasil (2006) Rev Saúde Pública, 40 (SUPPL.), pp. 109-19Hughes, J., McCauley, A.P., Improving the fit: Adolescents' needs and future programs for sexual and reproductive health in developing countries (1998) Stud Fam Plann, 29, pp. 233-45Díaz, M., Mello, M.B., Sousa, M.H., Cabral, F., Silva, R.C., Campos, M., Et al., Outcomes of three different models for sex education and citizenship programs concerning knowledge, attitudes, and behavior of Brazilian adolescents (2005) Cad Saúde Pública, 21, pp. 589-97(1999) Projeto Educação Afetivo-sexual: Sucessos E Desafios Na Educação Sexual De Adolescentes Da Rede Pública Estadual De Ensino De Belo Horizonte - Relatório Da Avaliação Externa, , Centro de Pesquisas em Saúde Reprodutiva de Campinas/Fundação Odebrecht, Campinas: Centro de Pesquisas em Saúde Reprodutiva de Campinas/Salvador: Fundação OdebrechtCosta, A.C.G., (2000) Protagonismo Juvenil: Adolescência, Educação E Participação Democrática, , Salvador: Fundação OdebrechtAndrade, H.H.S.M., Marques, C.M., Gouveia, M.C., Gregório, Y.M., Atendimento ambulatorial de adolescentes: A experiência do PAIA/ABEB (1996) J Pediatr (rio J), 72, pp. 319-23Cronbach, L.J., Coefficient alpha and the internal structure of tests (1951) Psychometrika, 16, pp. 297-334Mello, M.B., Fruet, M.S.B., Diaz, M., Silva, R.C., Paiva, V., Avaliação preliminar de impactos de um programa de orientação sexual de longa duração (1999) Anais Do Vii Congresso Brasileiro De Sexualidade Humana, p. 74. , Rio de Janeiro: Sociedade Brasileira de Estudos em Sexualidade HumanaFleiss, J.L., (1981) Statistical Methods For Rates and Proportions, , 2nd Ed. New York: John Wiley and SonsBertrand, J.T., Magnani, R.J., Rutenberg, N., (1996) Evaluating Family Planning Programs: With Adaptations For Reproductive Health, , Chapel Hill: Carolina Population Center, University of North Carolina at Chapel HillHosmer, D.W., Lemeshow, S., (1989) Applied Logistic Regression, , New York: John Wiley and SonsGrunseit, A., Kippax, S., (1997) Impact of Hiv and Sexual Health Education On the Sexual Behaviour of Young People: A Review Update, , Geneva: United Nations Joint Programme on HIV/AIDSKirby, D., (1995) A Review of Educational Programs to Designed to Reduce Sexual Risk-taking Behaviors Among School-aged Youth In the United States, , Santa Cruz: ETR AssociatesKirby, D., (2001) Emerging Answers: Research Findings On Programs to Reduce Teen Pregnancy, , Washington DC: National Campaign to Prevent Teen PregnancyAntunes, M.C., Peres, C.A., Paiva, V., Stall, R., Hearst, N., Diferenças na prevenção da AIDS entre homens e mulheres jovens de escolas públicas em São Paulo, SP (2002) Rev Saúde Pública, 36 (4 SUPPL.), pp. 88-95Magnani, R.J., Gaffikin, L., Aquino, E.M.L., Seiber, E.E., Almeida, M.C.C., Lipovsek, V., Impact of an integrated adolescent reproductive health program in Brazil (2001) Stud Fam Plann, 32, pp. 230-43Taquette, S.R., Vilhena, M.M., Paula, M.C., Doenças sexualmente transmissíveis e gênero: Um estudo transversal com adolescentes no Rio de Janeiro (2004) Cad Saúde Pública, 20, pp. 282-90Oliveira, F.A., Pfleger, V., Lang, K., Heukelbach, J., Miralles, I., Fraga, F., Sexually transmitted infections, bacterial vaginosis, and candidiasis in women of reproductive age in rural Northeast Brazil: A population-based study (2007) Mem Inst Oswaldo Cruz, 102, pp. 751-6(1999) Adolescentes, Jovens E a Pesquisa Nacional Sobre Demografia E Saúde: Um Estudo Sobre Fecundidade, Comportamento Sexual E Saúde Reprodutiva, , Bem-Estar Familiar no Brasil, Rio de Janeiro: Bem-Estar Familiar no BrasilAlmeida, M.C., Aquino, E.M., Barros, A.P., School trajectory and teenage pregnancy in three Brazilian state capitals (2006) Cad Saúde Pública, 22, pp. 1397-409Chalem, E., Mitsuhiro, S.S., Ferri, C.P., Barros, M.C.M., Guinsburg, R., Laranjeira, R., Gravidez na adolescência: Perfil sócio-demográfico e comportamental de uma população da periferia de São Paulo (2007) Brasil. 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    Spin transport of electrons through quantum wires with spatially-modulated strength of the Rashba spin-orbit interaction

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    We study ballistic transport of spin-polarized electrons through quantum wires in which the strength of the Rashba spin-orbit interaction (SOI) is spatially modulated. Subband mixing, due to SOI, between the two lowest subbands is taken into account. Simplified approximate expressions for the transmission are obtained for electron energies close to the bottom of the first subband and near the value for which anticrossing of the two lowest subbands occurs. In structures with periodically varied SOI strength, {\it square-wave} modulation on the spin transmission is found when only one subband is occupied and its possible application to the spin transistor is discussed. When two subbands are occupied the transmission is strongly affected by the existence of SOI interfaces as well as by the subband mixing

    Identification of human proteins that modify misfolding and proteotoxicity of pathogenic ataxin-1

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    Proteins with long, pathogenic polyglutamine (polyQ) sequences have an enhanced propensity to spontaneously misfold and self-assemble into insoluble protein aggregates. Here, we have identified 21 human proteins that influence polyQ-induced ataxin-1 misfolding and proteotoxicity in cell model systems. By analyzing the protein sequences of these modifiers, we discovered a recurrent presence of coiled-coil (CC) domains in ataxin-1 toxicity enhancers, while such domains were not present in suppressors. This suggests that CC domains contribute to the aggregation- and toxicity-promoting effects of modifiers in mammalian cells. We found that the ataxin-1–interacting protein MED15, computationally predicted to possess an N-terminal CC domain, enhances spontaneous ataxin-1 aggregation in cell-based assays, while no such effect was observed with the truncated protein MED15ΔCC, lacking such a domain. Studies with recombinant proteins confirmed these results and demonstrated that the N-terminal CC domain of MED15 (MED15CC) per se is sufficient to promote spontaneous ataxin-1 aggregation in vitro. Moreover, we observed that a hybrid Pum1 protein harboring the MED15CC domain promotes ataxin-1 aggregation in cell model systems. In strong contrast, wild-type Pum1 lacking a CC domain did not stimulate ataxin-1 polymerization. These results suggest that proteins with CC domains are potent enhancers of polyQ-mediated protein misfolding and aggregation in vitro and in vivo

    Resolution of dark matter problem in f(T) gravity

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    In this paper, we attempt to resolve the dark matter problem in f(T) gravity. Specifically, from our model we successfully obtain the flat rotation curves of galaxies containing dark matter. Further, we obtain the density profile of dark matter in galaxies. Comparison of our analytical results shows that our torsion-based toy model for dark matter is in good agreement with empirical data-based models. It shows that we can address the dark matter as an effect of torsion of the space.Comment: 14 pages, 3 figure
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