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Thresholds for gully initiation and sedimentation in Mediterranean Europe

Vandekerckhove, L.; Poesen, Jean; Oostwoud-Wijdenes, D.; Nachtergaele, J.; Kosmas, D.; Roxo, M. J.; Figueiredo, Tomás de
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.35%
In Mediterranean areas the dynamics of gully development act as an important indicator of desertification. However, little is known about the influence of climate and land-use changes, and almost no field data exist to assess the sensitivity of a landscape to gully erosion. Two important components of gully erosion studies are the prediction of where gullies begin and where they end. To address some of these issues, topographical thresholds for gully initiation and sedimentation in six different Mediterranean study areas were established. Field measurements of local soil surface slope (S) and drainage-basin area (A) at the point of initiation of ephemeral gullies in intensively cultivated fields (five datasets) and permanent gullies in rangelands (three datasets) were carried out. A negative power relationship of the form S = aA−b was fitted through all datasets, and defined as the mean topographical threshold for gullying in the respective area. Topographically controlled slopes of sedimentation at the gully bottom were also measured. Compared to theoretical relationships for channel initiation by overland flow, relatively low values for b are obtained, suggesting a dominance of overland flow and an influence of subsurface flow. The influence of landsliding at steeper slopes appeared from the flattening of the overall negative trend in the higher slope range (S > 0·30) of the integrated dataset. Comparing the threshold lines of our datasets to the average trend lines through data found in literature revealed that vegetation type and cover could better explain differences in topographical thresholds level than climatic conditions. In cultivated fields...

Testing the influence of far-field topographic forcing on subduction initiation at a passive margin

Marques, Fernando O.; Nikolaeva, Ksenia; Assumpcao, Marcelo Sousa de; Gerya, Taras V.; Bezerra, Francisco H.R.; Nascimento, Aderson F. do; Ferreira, Joaquim M.
Fonte: Amsterdam Publicador: Amsterdam
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.39%
Despite favourable gravitational instability and ridge-push, elastic and frictional forces prevent subduction initiation fromarising spontaneously at passive margins. Here,we argue that forces arising fromlarge continental topographic gradients are required to initiate subduction at passivemargins. In order to test this hypothesis,we use 2Dnumerical models to assess the influence of the Andean Plateau on stressmagnitudes and deformation patterns at the Brazilian passive margin. The numerical results indicate that “plateau-push” in this region is a necessary additional force to initiate subduction. As the SE Brazilianmargin currently shows no signs of self-sustained subduction, we examined geological and geophysical data to determine if themargin is in the preliminary stages of subduction initiation. The compiled data indicate that the margin is presently undergoing tectonic inversion, which we infer as part of the continental–oceanic overthrusting stage of subduction initiation. We refer to this early subduction stage as the “Brazilian Stage”, which is characterized by N10 kmdeep reverse fault seismicity at themargin, recent topographic uplift on the continental side, thick continental crust at themargin, and bulging on the oceanic side due to loading by the overthrusting continent. The combined results of the numerical simulations and passivemargin analysis indicate that the SE Brazilian margin is a prototype candidate for subduction initiation.; ETH Research Grant TH-12/05-3; SNF Research Grant 200021-113672/1; CNPq

Leucine-rich diet alters the eukaryotic translation initiation factors expression in skeletal muscle of tumour-bearing rats

Ventrucci, Gislaine; Mello, Maria Alice R.; Gomes-Marcondes, Maria Cristina C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
Background: Cancer-cachexia induces a variety of metabolic disorders on protein turnorver, decreasing protein synthesis and increasing protein degradation. Controversly, insulin, other hormones, and branched-chain amino acids, especially leucine, stimulate protein synthesis and modulate the activity of translation initiation factors involved in protein synthesis. Since the tumour effects are more pronounced when associated with pregnancy, ehancing muscle-wasting proteolysis, in this study, the influence of a leucine-rich diet on the protein synthesis caused by cancer were investigated. Methods: Pregnant rats with or without Walker 256 tumour were distributed into six groups. During 20 days of experiment, three groups were fed with a control diet: C - pregnant control, W - tumour-bearing, and P - pair-fed, which received the same amount of food as ingested by the W group; three other groups of pregnant rats were fed a leucine-rich diet: L - pregnant leucine, WL - tumour-bearing, and PL - pair-fed, which received the same amount of food as ingested by the WL group. Results: The gastrocnemius muscle of WL rats showed increased incorporation of leucine in protein compared to W rats; the leucine-rich diet also prevented the decrease in plasma insulin normally seen in W. The expression of translation initiation factors increased when tumour-bearing rats fed leucine-rich diet...

Pedagogia do esporte e a iniciação ao tenis de campo : um estudo nos principais clubes de São Paulo; Sport pedagogy and the initiation to tennis : a study in the main sport clubs in São Paulo

Sabine Zink Bolonhini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/12/2009 PT
Relevância na Pesquisa
36.39%
Esse estudo promove, no primeiro momento, uma discussão teórica acerca da Pedagogia do Esporte e da iniciação esportiva ao Tênis de Campo. As reflexões basearam-se a partir dos autores que defendem a proposta pedagógica do Teaching Games For Understanding (TGFU). No decorrer das discussões teóricas, foi realizado um diálogo entre as propostas desses autores e as reflexões de autores brasileiros que abordam o tema da Pedagogia do Esporte. É importante ressaltar que, a partir do encontro e da comparação das propostas de dois grupos de autores, é possível contribuir de maneira significativa para avanços da produção teórica no tema da Pedagogia do Esporte e Iniciação Esportiva. Além de contribuir com a construção de um referencial teórico, este estudo teve como objetivo verificar quais as características da Iniciação Esportiva nos 4 principais clubes do Estado de São Paulo. Para isso, foi realizada uma pesquisa de campo dividida em dois momentos: realização de entrevistas semi-estruturadas com os professores envolvidos com as aulas de iniciação esportiva nos clubes e a realização de observações não-participantes das aulas ministradas por esses professores. O objetivo das entrevistas foi o de verificar o perfil do profissional que trabalha com a iniciação esportiva à modalidade: sua formação escolar...

A pesquisa na formação do estudante universitário : a iniciação científica como espaço de possibilidades; Research in the formation of undergraduate : scientific initiation as a space of possibilities

Jamile Cristina Ajub Bridi
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/02/2010 PT
Relevância na Pesquisa
36.43%
A universidade, em quase todos os países do mundo, tem o papel de contribuir com a sociedade tanto por meio da produção de conhecimento através da pesquisa científica como pela formação de profissionais e de cidadãos. A ênfase da pesquisa na graduação inicia-se com Humboldt, responsável pela criação de um modelo emblemático de universidade voltada para a pesquisa, ressaltando aspectos totalmente relevantes nos dias atuais como a interdisciplinaridade, a autonomia acadêmica e científica, a formação pela pesquisa e a indissociabilidade do ensino e da pesquisa. O presente trabalho analisa a atividade de Iniciação Científica desenvolvida em uma universidade pública do estado de São Paulo, a Universidade Estadual de Campinas (UNICAMP), partindo da suposição de que o espaço da Iniciação Científica vai além da formação do pesquisador especializado, contribuindo para a formação intelectual e moral do estudante. Nosso objetivo principal é identificar, através da percepção de alunos e de professores (orientadores) envolvidos nessa atividade, os espaços de formação de um espírito investigativo tal como o pensado pela proposta Humboldtiana da universidade moderna. Os sujeitos são os alunos inseridos em agosto de 2008 nos programas oficiais de Iniciação Científica da Unicamp...

Stochastic model of transcription initiation of closely spaced promoters in escherichia coli

Martins, Leonardo Pedro Donas-Boto de Vilhena
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2011 ENG
Relevância na Pesquisa
36.39%
Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica; The regulatory mechanisms of transcription allow organisms to quickly adapt to changes in their environment and often act during transcription initiation. Here, a stochastic model of transcription initiation at the nucleotide level is proposed to study the dynamics of RNA production in closely spaced promoters and their regulatory mechanisms. We study how different arrangements (convergent e divergent), distance between transcription start sites (TSS), and various kinetic parameters affect the dynamics of RNA production. Further, we analyze how the kinetics of various steps in transcription initiation can be regulated by varying locations of repressor binding sites. From the results, we observe that the rate limiting steps have strong influence in the kinetics of RNA production. We find that interferences between RNA polymerases in divergent overlapped and convergent geometries causes the distribution of time intervals between the production of consecutive RNA molecules from each TSS to increase in mean and standard deviation, which leads to stronger fluctuations in the temporal levels of RNA molecules. We observe that small changes in the distance between TSSs can lead to abrupt transitions in the dynamics of RNA production...

Rite of Passage, Kyriarchic Warrior Mentality, or Issues with Father? Universal Elements of Male Initiation and their Potential for Men in the West

Fanning, Ian Robert
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
36.52%
The decline of male initiation rituals in the West is lamented by authors articulating a variety of perspectives. However, the full extent of the decline and the subsequent impact on men, women and children is difficult to measure. There are many different descriptions of male initiation and many different conclusions regarding its purpose. Rather than concluding that the decline of male initiation contributes to hypermasculine behaviours or that the decline of male initiation frees men from forms of oppression, in this essay I both review a number of approaches in an assessment of current literature and undertake a search for common elements in such rituals with a view to determining whether a “good” ritual or rite of initiation for men in the West is possible, and, if so, what it might include. Identification of universal elements of male initiation across different approaches provides a starting point for re-defining and recovering “male initiation” in the West. Three of the most prominent approaches to male initiation in the West are those of ritual theorists, those of Christian ministers and scholars, and those of secular practitioners and writers. This paper examines perspectives on male initiation and the sub-topics within each of the three approaches. It traces the development of each perspective and identifies common elements of male initiation. Arguments will be made for the rejection of certain elements not common to all three approaches. My concluding analysis will review the elements I find to be universal and potentially valuable to new rites for men in the West.

Time Trends and Predictors of Initiation for Cigarette and Waterpipe Smoking Among Jordanian School Children: Irbid, 2008-2011

McKelvey, Karma L, PhD
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
36.47%
Smoking prevalence among adolescents in the Middle East remains high while rates of smoking have been declining among adolescents elsewhere. The aims of this research were to (1) describe patterns of cigarette and waterpipe (WP) smoking, (2) identify determinants of WP smoking initiation, and (3) identify determinants of cigarette smoking initiation in a cohort of Jordanian school children. Among this cohort of school children in Irbid, Jordan, (age ≈ 12.6 at baseline) the first aim (N=1,781) described time trends in smoking behavior, age at initiation, and changes in frequency of smoking from 2008-2011 (grades 7 – 10). The second aim (N=1,243) identified determinants of WP initiation among WP-naïve students; and the third aim (N=1,454) identified determinants of cigarette smoking initiation among cigarette naïve participants. Determinants of initiation were assessed with generalized mixed models. All analyses were stratified by gender. Baseline prevalence of current smoking (cigarettes or WP) for boys and girls was 22.9% and 8.7% respectively. Prevalence of ever- and current- any smoking, cigarette smoking, WP smoking, and dual cigarette/WP smoking was higher in boys than girls each year (p These studies reveal intensive smoking patterns at early ages among Jordanian youth in Irbid...

Single and multiple transverse fracture initiation from horizontal wells

Crosby, D. G.; Rahman, Md Motiur; Rahman, M. K.; Rahman, S. S.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
Relevância na Pesquisa
36.52%
The results of an analytical and experimental study of the initiation of transverse fractures from horizontal wells are presented. Analytical criteria for the initiation of single hydraulic fracture are reviewed, and criterion for initiation of multiple hydraulic fractures was developed by modification of the existing Drucker and Prager criterion for single hydraulic fracture initiation. The developed criterion for multiple fracture initiation was validated by comparisons with actual hydraulic fracture initiation pressures, which were obtained from scaled laboratory experiments and numerical results from boundary element analysis. Other criteria are assessed against the experimental results. Experimentally obtained transverse fracture initiation pressures were found close to longitudinal fracture initiation pressures estimated from maximum tensile stress criterion and Hoek and Brown criterion. One possible explanation of this finding is presented. Results from Drucker and Prager criteria for single and multiple fracture initiation were, however, found closer to experimental values. Therefore, these criteria could be useful to engineers involved with hydraulic fracturing for predicting transverse fracture initiation pressures from horizontal wells drilled parallel to the minimum horizontal in-situ stress.; D. G. Crosby...

Molecular characterisation of primary wool follicle initiation in Merino sheep.

McGrice, Hayley Ann
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
36.45%
Primary wool follicles are initiated in the skin of sheep foetuses at approximately day 50 of gestation as the result of complex reciprocal molecular interactions between the mesenchyme and overlying epithelium. The lifetime wool production potential and fibre diameter of the Merino sheep is dependent on the total number of follicles initiated in utero. Understanding the molecular events that surround primary wool follicle initiation may provide approaches to enhance or manipulate this process in order to maximise the profitability of wool production enterprises. In order to study the morphological and molecular changes occurring during early wool follicle development, a foetal skin series spanning primary follicle initiation was generated. Foetal skin was sampled from the shoulder, midside and rump of four foetuses at 8 time points between day 43 and day 68 of gestation. Histological characterisation of the shoulder skin samples revealed that primary epidermal placodes emerged at around day 53, dermal condensates were visible from day 57 and downgrowth of the follicle began at day 68. An equation relating age of the foetus (day of gestation post AI) and crown-rump length, specific to Merino foetuses, was developed for use in future studies of this nature. Molecular markers of fibroblast migration...

Inoculation with arbuscular mycorrhizal fungi suppresses initiation of haustoria in the root hemiparasite Pedicularis tricolor

Li, A.R.; Smith, S.; Smith, F.; Guan, K.Y.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
36.39%
BACKGROUND AND AIMS: Plant parasitism and arbuscular mycorrhizal (AM) associations have many parallels and share a number of regulatory pathways. Despite a rapid increase in investigations addressing the roles of AM fungi in regulating interactions between parasitic plants and their hosts, few studies have tested the effect of AM fungi on the initiation and differentiation of haustoria, the parasite-specific structures exclusively responsible for host attachment and nutrient transfer. In this study, we tested the influence of AM fungi on haustorium formation in a root hemiparasitic plant. METHODS: Using a facultative root hemiparasitic species (Pedicularis tricolor) with the potential to form AM associations, the effects of inoculation were tested with two AM fungal species, Glomus mosseae and Glomus intraradices, on haustorium initiation in P. tricolor grown alone or with Hordeum vulgare ‘Fleet’ (barley) as the host plant. This study consisted of two greenhouse pot experiments. KEY RESULTS: Both AM fungal species dramatically suppressed intraspecific haustorium initiation in P. tricolor at a very low colonization level. The suppression over-rode inductive effects of the parasite’s host plant on haustoria production and caused significant growth depression of P. tricolor. CONCLUSIONS: AM fungi had strong and direct suppressive effects on haustorium formation in the root hemiparasite. The significant role of AM fungi in haustorium initiation of parasitic plants was demonstrated for the first time. This study provides new clues for the regulation of haustorium formation and a route to development of new biocontrol strategies in management of parasitic weeds.; Ai-Rong Li...

A novel mechanism for the control of translation initiation by amino acids, mediated by phosphorylation of eukaryotic initiation factor 2B

Wang, X.; Proud, C.
Fonte: Amer Soc Microbiology Publicador: Amer Soc Microbiology
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
Relevância na Pesquisa
36.39%
Eukaryotic initiation factor 2B (eIF2B) plays a key role in controlling the initiation of mRNA translation. eIF2B is heteropentamer whose catalytic (ε) subunit promotes GDP/GTP exchange on eIF2. We show here that depriving human cells of amino acids rapidly results in the inhibition of eIF2B, independently of changes in eIF2 phosphorylation. Although amino acid deprivation also inhibits signaling through the mammalian target of rapamycin complex 1 (mTORC1), the inhibition of eIF2B activity by amino acid starvation is independent of mTORC1. Instead, amino acids repress the phosphorylation of a novel site in eIF2Bε. We identify this site as Ser525, located adjacent to the known phosphoregulatory region in eIF2Bε. Mutation of Ser525 to Ala abolishes the regulation of eIF2B and protein synthesis by amino acids. This indicates that phosphorylation of this site is crucial for the control of eIF2B and protein synthesis by amino acids. These findings identify a new way in which amino acids regulate a key step in translation initiation and indicate that this involves a novel amino acid-sensitive signaling mechanism.; Xuemin Wang and Christopher G. Proud

ABC50 promotes translation initiation in mammalian cells

Wang, X.; Paytubi, S.; Lam, Y.; Izquierdo, L.; Hunter, M.; Jan, E.; Hundal, H.; Proud, C.
Fonte: Amer Soc Biochemistry Molecular Biology Inc Publicador: Amer Soc Biochemistry Molecular Biology Inc
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
36.45%
ABC50 is an ATP-binding cassette (ABC) protein, which, unlike most ABC proteins, does not possess membrane-spanning domains. ABC50 interacts with eukaryotic initiation factor 2 (eIF2), which plays a key role in translation initiation and its control. ABC50 binds to ribosomes, and this interaction requires both the N-terminal domain and at least one ABC domain. Knockdown of ABC50 by RNA interference impaired translation of both cap-dependent and -independent reporters, consistent with a positive role for ABC50 in the function of eIF2, which is required for both types of translation initiation. Mutation of the Walker box A or B motifs in both ABC regions of ABC50 yielded a mutant protein that exerted a dominant-interfering phenotype with respect to protein synthesis and translation initiation. Importantly, although dominant-interfering mutants of ABC50 impaired cap-dependent translation, translation driven by certain internal ribosome entry segments was not inhibited. ABC50 is located in the cytoplasm and nucleoplasm but not in the nucleolus. Thus, ABC50 is not likely to be directly involved in early ribosomal biogenesis, unlike some other ABC proteins. Taken together, the present data show that ABC50 plays a key role in translation initiation and has functions that are distinct from those of other non-membrane ABC proteins.; Sonia Paytubi...

Fracture Initiation and Propagation in Low Porosity Crystalline Rocks: Implications for Excavation Damage Zone (EDZ) Mechanics

Ghazvinian, Ehsan
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.35%
The Deep Geological Repository (DGR) is the globally preferred concept for long-term storage of nuclear waste, in which the combination of engineered barriers and the surrounding geology are designed to safely and securely contain the radioactive waste. The construction processes of underground openings in hard rocks at depth are commonly associated with introducing some damage to the surrounding rock mass through the initiation and propagation of fractures parallel to the excavation boundary due to disturbance to the in situ stress condition, as well as the excavation process quality. The induced fractures in depth away from the excavation surface can provide a migration path for the radionuclides in case of damage to the engineered barriers. Therefore, different damage zones are defined according to the crack density and change in hydraulic permeability of the rock mass surrounding the waste storage tunnel and rooms, these are commonly referred to as the Excavation Damage Zones (EDZs). Crack initiation (CI) and propagation (CD) characteristics of massive rock masses have a significant influence on the mechanics and geometry of EDZs, and this research aims to provide a better understanding of these parameters for brittle rocks. This research addresses the short- and long-term in situ behaviour of massive brittle rock masses through characterization of the micro-mechanics of crack initiation and crack damage progress for rock specimens in the laboratory. Particular attention is paid to formulize the laboratory estimation of the crack damage thresholds. The effect of inherent fabric in intact rocks on the fabric-guided micro-fracturing is investigated through laboratory tests on different rock types. Similarly...

High cycle multiaxial fatigue crack initiation : experimental observations and microstructure simulations

AGBESSI, Komlan; SAINTIER, Nicolas; PALIN-LUC, Thierry
Fonte: Arts et Métiers ParisTech Publicador: Arts et Métiers ParisTech
Relevância na Pesquisa
36.35%
This study provides an analysis of high cycle multiaxial fatigue crack initiation modes based on SEM observations.The statistical study of crack initiation preferential sites shows that grains with multiple slip have a high probability of crack initiation. The application of Dang Van criterion at the grain scale using finite element analysis (cubic elasticity with / or without crystal plasticity) on 3D synthetic semi-periodic microstructures shows a strong heterogeneity of both the hydrostatic stress and shear. The evolution of this heterogeneity introduced by the material behavior is discussed. Finally, a method based on the extreme values statistics is proposed and applied to the fatigue indicative parameter associated to the Dang Van criterion. The effects of free surface and constitutive material model were analyzed.

Ribosome-Mediated Specificity in Vesicular Stomatitis Virus mRNA Translation Defines a New Role for rpL40 during Initiation

Lee, Amy
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
36.35%
Vesicular stomatitis virus (VSV) infection causes inhibition of host protein synthesis, in part by sequestering initiation factors required for mRNA cap recognition. The viral mRNAs share a common mRNA structure to those of the host cell, with a 5' cap and 3' polyadenylate tail, but continue to be efficiently translated despite host translational shutoff. This observation suggests that a non-canonical translation pathway is utilized for viral protein synthesis. To investigate this pathway, we performed an RNA interference screen to identify genes required for VSV replication. In contrast to bulk cellular translation, viral translation is hypersensitive to knockdown of a protein constituent of the 60S ribosomal subunit, rpL40. Depletion of rpL40 diminishes VSV protein synthesis by >90% and is restored through complementation with an siRNA-resistant mutant of rpL40. To delineate the mechanism by which rpL40 is required for viral protein synthesis, we reconstituted translation of VSV mRNA in yeast extracts in vitro. In the absence of rpL40, we show that the two ribosomal subunits fail to associate on VSV mRNA, and the small subunit does not scan to the initiation codon. Regulation by rpL40 occurs in context of the large subunit, providing direct evidence for translational control by the ribosome itself. This rpL40- dependent mechanism of translation initiation is broadly conserved within eukaryotes...

Iniciação sexual entre adolescentes de Pelotas, Rio Grande do Sul; Sexual initiation among adolescents of Pelotas, state of Rio Grande do Sul

Cruzeiro, Ana Laura Sica; Souza, Luciano Dias de Mattos; Silva, Ricardo Azevedo da; Horta, Bernardo Lessa; Muenzer, Renata Mendes; Faria, Augusto Duarte; Pinheiro, Ricardo Tavares
Fonte: Universidade de São Paulo. Faculdade de Saúde Pública Publicador: Universidade de São Paulo. Faculdade de Saúde Pública
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/08/2008 POR
Relevância na Pesquisa
36.35%
O objetivo do presente estudo foi avaliar a idade de início das atividades sexuais e fatores associados em adolescentes. Realizou-se estudo transversal em uma amostra representativa de adolescentes de 15 a 18 anos residentes na cidade de Pelotas. Sortearam-se, aleatoriamente, 90 setores a partir de 448 setores censitários, em cada setor foram visitados 86 domicílios. Os adolescentes respondiam a um questionário auto-aplicado e anônimo contendo questões sobre nível socioeconômico, sexo, escolaridade do adolescente e dos pais, idade, religião, morar com os pais, trabalho remunerado, uso de drogas, tabagismo, consumo de álcool e comportamento sexual. A iniciação sexual foi avaliada através da idade da primeira relação. A mediana da idade da primeira relação sexual foi calculada usando-se tabelas de sobrevida, e as medianas foram comparadas através do long rank teste e na análise multivariada utilizou-se a regressão de Cox. Foram entrevistados 960 adolescentes. A mediana da idade da primeira relação sexual foi de 16,7 anos. O risco de ter iniciação sexual em uma idade mais jovem foi maior entre os homens, assim como naqueles adolescentes que não residem com a mãe ou com o pai. O mesmo ocorreu com os jovens que não possuem trabalho remunerado...

Control of axillary bud initiation and shoot architecture in Arabidopsis through the SUPERSHOOT gene

Tantikanjana, T; Yong, Jean; Letham, D Stuart; Griffith, Megan; Hussein, M S; Ljung, Karen; Sandberg, Goran; Sundaresan, Venkatesan
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.35%
The aerial architecture of flowering plants is determined to a large extent by shoot growth and shoot branching arising from the initiation and growth of axillary meristems. We have identified an Arabidopsis mutant, supershoot (sps), which is characterized by a massive overproliferation of shoots, such that a single plant can generate 500 or more inflorescences. Analysis of the mutant plants shows that the primary defect is because of an increase in the number of meristems formed in leaf axils, together with release of bud arrest, resulting in reiterative branch formation from rosette and cauline leaves. The SPS gene is shown here to encode a cytochrome P450, and together with a 3- to 9-fold increase in levels of Z-type cytokinins in sps mutant plants, indicate a role for SPS in modulating hormone levels. The expression pattern of SPS, with strong expression at the leaf axils, correlates well with the phenotypic defects. Our results indicate that control of shoot branching in Arabidopsis may be accomplished in part by suppression of axillary meristem initiation and growth through the localized attenuation of cytokinin levels at sites of bud initiation.

Escape tactics and effects of perch height and habituation on flight initiation distance in two Jamaican anoles (Squamata: Polychrotidae)

Cooper, Jr,William E
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
36.45%
Escape by Anolis lizards is influenced by microhabitats and fight initiation distance increases with predation risk. Differences in microhabitat use among ecomorphs affect escape behavior, but only two studies have reported ecomorphological differences in flight initiation distance among Greater Antillean species. I studied effects of predation risk and microhabitats on escape behavior by conducting field experiments using two species of anoles, Anolis lineatopus and A. grahami, on the campus of the University of the West Indies at Mona, Jamaica. Because ecomorphological variation of anoles has evolved independently within each island of the Greater Antilles, but relationships between ecomorphs and escape behaviors are poorly known, I characterized microhabitat use and escape tactics, and determined relationships between flight initiation distance and two risk factors, habituation to human presence and perch height, in Anolis lineatopus, a trunk-ground anole and A. grahami, a trunk-crown anole. Sample sizes for A. lineatopus and A. grahami were 214 and 93, for microhabitat use and escape destinations, 74 and 34 for human presence and 125 and 34 for perch height. The two species occurred in similar microhabitats and exhibited similar escape tactics...

Some views of Xhosa women regarding the initiation of their sons

Venter,M.A.
Fonte: Koers Publicador: Koers
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
36.47%
Notwithstanding attempts from the Eastern Cape Department of Health and other organisations to regulate the process of initiation, each year initiates still die or are mutilated. The challenge is to keep the boys safe without interfering with the traditional customs. It appears that women's voices are rarely heard on this issue. Through a literature review the author attempts to understand the rite of initiation from a cultural perspective. The general meaning and specific usage of concepts such as 'culture', 'traditional', and 'masculinity' are explained, as well as how these concepts are used in the article. A questionnaire was designed and administered to establish the views of Xhosa women on the ritual of initiation. On comparing these results with results from previous research, it shows a decline in the number of women who favour the traditional way of initiation without medical intervention. Although this indicates a shift in women's views, a conflict is evident, as there is still overwhelming agreement that traditional initiation is a prerequisite for becoming a man who is respected by his community. The empirical research indicates that although women are forbidden to take part in discussions on this subject, some women did take the liberty to express their opinions.