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The Computational and Qualitative Analysis of Failures in the Studies on the Vulnerability of Guyed Towers Modelación computacional y análisis cualitativo de fallas en el estudio de la vulnerabilidad de torres atirantadas de telecomunicaciones
Vivian Elena Parnás,Patricia Martín Rodríguez
Revista Cubana de Ingeniería , 2011, DOI: 10.1234/rci.v2i1.37
Abstract: Guyed masts are a specialized type of structure commonly used in the broadcasting industry to support equipment at substantial heights. Surprisingly, the failure rate of this structural typology with respect to others of similar complexity is high. Therefore, this study searches for the reason behind the failure of telecommunication towers under extreme wind action, which does so by making a comparison between qualitative analysis and the physical –mathematic computational models of the failed towers. The results of the physical- mathematic models are obtained by means of a non – lineal geometric analysis of the structures. Results are then discussed after which are used to outline the importance of both studies as a means of validating results Las torres atirantadas son estructuras comúnmente empleadas en el área de las telecomunicaciones que soportan antenas a grandes alturas. El índice de fallo de esta tipología estructural con respecto a otras de similar complejidad es elevado. En este trabajo se expone el análisis de torres de telecomunicaciones falladas bajo la acción de vientos extremos a partir de la comparación entre el análisis cualitativo y la modelación físico-matemática de la torre fallada. Los resultados de la modelación físico-matemática se obtienen por medio del análisis no lineal geométrico de la estructura. Ambos estudios, por su importancia y necesidad, son empleados como vía para validar los resultados.
Non-Linear Geometric Analysis in Guyed Masts No linealidad geométrica en torres atirantadas
Vivian Elena Parnás,Ingrid Fernández Lorenzo
Revista Cubana de Ingeniería , 2011, DOI: 10.1234/rci.v2i3.56
Abstract: A guyed mast is an example of structures with non-lineal behaviour under extreme wind loads. Cables are used to stabilize structures; changes in the stiffness of these structures give rise to non linearity. The variations in stiffness are produced as results of displacements of structures under wind loads and of variations in tension in cables. The aim of this paper is to analyse the variations obtained in internal stresses in tower members under extreme wind loads by considering and not considering the geometric non-linearity alternatively in order to value the necessity of non-lineal geometric application in guyed mast under extreme wind loads. Results obtained from the guyed mast model reflect considerable increases in stress in all members of the tower under non-linear analysis compared to linear analysis and confirm that linear analysis conduces to increases in vulnerability under wind loads and hence to an unsafe design. Las torres atirantadas son estructuras con un alto comportamiento estructural no lineal geométrico bajo la acción de cargas de viento extremas. La no linealidad es debida a los cambios en la rigidez que experimentan los cables que las estabilizan, lo cual se produce a partir de los desplazamientos de la estructura bajo cargas de dise o y la consecuente variación de tensión en los cables. Los cables a barlovento incrementan los valores de tensión mientras que los cables a sotavento experimentan distensión. Este trabajo tiene por objeto estudiar las variaciones en los esfuerzos internos obtenidos en los elementos de una torre atirantada bajo carga de viento extrema considerando la no linealidad geométrica y sin considerarla, a fin de valorar la necesidad de este tipo de análisis. Los resultados obtenidos de la modelación de la torre reflejaron incrementos significativos en los esfuerzos para todos los elementos, confirmando la necesidad de aplicación de análisis no lineal en torres bajo carga de viento extrema. Los resultados permiten afirmar que la no consideración de la no linealidad geométrica produce un au
Exploring the functional interaction between POSH and ALIX and the relevance to HIV-1 release
J?rg Votteler, Elena Iavnilovitch, Orit Fingrut, Vivian Shemesh, Daniel Taglicht, Omri Erez, Stefan S?rgel, Torsten Walther, Norbert Bannert, Ulrich Schubert, Yuval Reiss
BMC Biochemistry , 2009, DOI: 10.1186/1471-2091-10-12
Abstract: In this study we identified ALIX as a POSH ubiquitination substrate in human cells: POSH induces the ubiquitination of ALIX that is modified on several lysine residues in vivo and in vitro. This ubiquitination does not destabilize ALIX, suggesting a regulatory function. As it is well established that ALIX rescues virus release of L-domain mutant HIV-1, HIV-1ΔPTAP, we demonstrated that wild type POSH, but not an ubiquitination inactive RING finger mutant (POSHV14A), substantially enhances ALIX-mediated release of infectious virions derived from HIV-1ΔPTAP L-domain mutant (YPXnL-dependent HIV-1). In further agreement with the idea of a cooperative function of POSH and ALIX, mutating the YPXnL-ALIX binding site in Gag completely abrogated augmentation of virus release by overexpression of POSH. However, the effect of the POSH-mediated ubiquitination appears to be auxiliary, but not necessary, as silencing of POSH by RNAi does not disturb ALIX-augmentation of virus release.Thus, the cumulative results identified ALIX as an ubiquitination substrate of POSH and indicate that POSH and ALIX cooperate to facilitate efficient virus release. However, while ALIX is obligatory for the release of YPXnL-dependent HIV-1, POSH, albeit rate-limiting, may be functionally interchangeable.The release of nascent retrovirus particles requires the deployment of the ESCRT (endosomal sorting complex required for transport) to the site of virus budding at the cell surface [1-4]. ESCRT consists of four sub-complexes (ESCRT0-III) that normally reside on the cytoplasmic leaflet of the membrane of late endosomes where they function in tandem to target endocytosed plasma membrane proteins into mutivesicular bodies (MVBs) en route to lysosomes [5-7]. Recruitment of ESCRT to the site of virus budding is facilitated by interaction of specific ESCRT proteins with short peptide sequences termed late (L-) domains of retroviruses Gag proteins such as the p6 and p9 of human immunodeficiency virus (HIV)-1
EFECTO DE LA ADMINISTRACIóN INTRACEREBRAL DE MK-801 Y (-) NICOTINA EN LAS CONCENTRACIONES EXTRACELULARES DE GLU Y GABA EN EL NúCLEO PEDUNCULOPONTINO DE RATAS
BLANCO LEZCANO,LISETTE; LORIGADOS PEDRE,LOURDES DEL CARMEN; GONZáLEZ FRAGUELA,MARíA ELENA; SERRANO SáNCHEZ,TERESA; PAVóN FUENTES,NANCY; BLANCO LEZCANO,VIVIAN; FRANCIS TURNER,LILIANA;
Acta Biológica Colombiana , 2011,
Abstract: although the pharmacological manipulation of the glutamatergic and cholinergic systems have been studied in animal models of parkinson′s disease (pd), only some authors have done work on this topic at the pedunculopontine nucleus (ppn). the present work studied the changes in glutamate (glu) and δ-aminobutyric acid (gaba) extracellular concentrations (ec) in the ppn from hemiparkinsonian rats by 6hydroxydopamine injection. the rats were locally perfused by mk-801 (10 μmol/l) or (-) nicotine (10 mm) solutions by cerebral microdyalisis. the biochemical studies were carried out through high performance liquid chromatography coupled to fluorescence detection. mk-801 infusion induced a significant decrease of glu (p< 0.01) and gaba (p< 0.01) ec in ppn. on the other hand (-) nicotine infusion induced a significant increase of glu (p< 0.001) and gaba (p< 0.001) ec in ppn from hemiparkinsonian rats. the local blockade of nmda receptors by mk-801 infusion facilitates the interaction between glu and their metabotropic receptors that take part in presynaptic inhibition mechanisms and interfere with neurotransmitters release. meanwhile, the nicotine infusion sums the effects of nicotinic receptor activation with the glutamatergic and gabaergic neurotransmission changes produced in the ppn in the parkinsonian condition. the cholinergic and glutamergic drug infusion in ppn impose a new adjustment to the neurotransmition at this level that is added to the neurochemical changes associated to dopaminergic denervation.
Civic Education in Europe: Pedagogic Challenge versus Social Reality  [PDF]
Elena Arbués
Sociology Mind (SM) , 2014, DOI: 10.4236/sm.2014.43023
Abstract:
Since the final decade of the 20th century western democracies have witnessed the ongoing development and consolidation of education for democratic citizenship. It has been seen as a solution to specific problems faced by our societies (Cortina, 1997; Altarejos & Naval, 2005; Bolivar, 2007). Governments have attempted to implement the various recommendations of the Council of Europe (2002, 2010). The introduction of educational reforms and the ongoing development of curricula have provided an opportunity to include civic education in the national curriculum of most European countries (Naval, Print, & Veldhuis, 2002). The aim of this article is to suggest the likely future tendencies for this situation within Europe, bearing in mind, among other things, the challenges posed by an increasingly globalised and technological society as well as the objectives of the European Higher Education Area.
The Perception of South African Adolescents Regarding Primary Health Care Services
Magdalena S. Richter,Vivian Mfolo
The Scientific World Journal , 2006, DOI: 10.1100/tsw.2006.161
Abstract:
COMPLEXES OF Sn(IV) AND Zr(IV) WITH A SCHIFF BASE LIGAND DERIVED FROM ISATIN AND O-AMINOPHENOL
Angela Kriza,Carmen Parn?u,N. Popa
Analele Universitatii Bucuresti : Chimie , 2002,
Abstract:
Influencia del mesoclima sobre la madurez de fruto de toronjo (Citrus paradisi Macf.) en Cuba
Betancourt Grandal, Mayda;Sistachs Vega, Vivian;Sánchez García, Cira;García álvarez, María Eugenia;Nú?ez Vázquez, Miriam;Solano Ojeda, Oscar;Noriega Carrera, Caridad;Oliva Díaz, Hugo;Acosta Porta, Zita María;Delgado, Carmen Gloria;Martín Padrón, María Elena;
Agricultura técnica en México , 2006,
Abstract: climate constitutes a critical factor on plant development by limiting and modifying biological processes. this study was carried out during five consecutive years, during 2000 to 2004, in a commercial plantation of grapefruit (citrus paradisi macf.) cv. 'marsh seedless' in the island of youth (cuba). the objective of this research was to determine the influence of the mesoclimate during the yearly growth cycle on fruit maturity. the analysis was done in two stages of fruit development, a period from 121 to 180 and from 181 to 300 days after full bloom. total soluble solids, acidity, maturity index and juice content were evaluated and related to nine meteorological variables. these meteorological variables were considered at 10, 30 and 90 days before fruit sampling. results show that the interaction among different variables of the mesoclimate, such as temperature, wind speed, insolation, evapotranspiration, rainfall and relative humidity, modified the maturity of grapefruit, mainly during the second stage of fruit development.
Linfoma de Hodkin en Chile: Experiencia de 15 a?os del Programa Nacional de Cáncer del Adulto
Cabrera C,M Elena; García L,Hernán; Lois V,Vivian; León R,Alvaro; Pe?a N,Karina; Rossle S,Alberto; Cerda A,Berta; Rojas R,Hernán; Meneses C,Pedro; Merino M,Carlos; Aspillaga M,Augusto; Vittini de R,Cecilia; Oliva L,Jacqueline; Hales D,Cecilia; Rosas H,Janet;
Revista médica de Chile , 2007, DOI: 10.4067/S0034-98872007000300009
Abstract: background: hodgkin lymphoma is a highly curable disease. aim: to evaluate the clinical characteristics and the treatment results of hodgkin lymphoma patients of the national cancer program in chile. patients and methods: prospective assessment of 682 patients treated in 18 adult cancer centers. progression free survival (pfs) and overall survival (os) were calculated. median follow up was 127, 95, 87, 72 and 50 months for c-mopp, radiotherapy (rt), c-mopp/abv, novp and abvd, respectively. results: median age was 37 years (15-84). nodular sclerosis and mixed cellularity were equally expressed. advanced stages (iii & iv) were present at diagnosis in 61% of cases. age over 40 was an adverse prognostic factor (p <0.001). the rate of pfs at 5 and 10 years for early stages was 73% and 66% with rt, 80% and 74% with c-mopp+rt, 73% and 71% with c-mopp/abv, 59% and 59% with novp+rt, and 81% with abvd+rt, at 5 years, being significantly lower for novp (p =0.02). the rate of os at 5 and 10 years for advanced stages was 82% and 70% with rt, 82% and 76% with c-mopp+rt, 82% and 80% with c-mopp/abv, 68% and 60% with novp, and 85% with abvd at 5 years, also significantly lower for novp (p =0.04). for advanced stages, the rate of pfs at 5 and 10 years was 49% and 43% with c-mopp, 69% and 62% with c-mopp/abvd or c-mopp/abv, and 71% at 5 years with abvd, significantly lower for c-mopp (p =0.01). the rate of os at 5 and 10 years was 52% and 46% with c-mopp, 70% and 63% with c-mopp/abvd or c-mopp/abv and 76% with abvd at 5 years, significantly lower for c-mopp (p =0.0002). conclusions: age over 40 years was an adverse prognostic factor. c-mopp/abvd, c-mopp/abv and abvd had comparable results and reached a high tumor control and overall survival in both early and advanced stages
Know about your English learning process: checklists as a means of self-assessment
Martínez Sánchez,Vivian A;
Educaci?3n M??dica Superior , 2003,
Abstract: a way to sort out questions students migth ask themselves to face the responsability of improving their perfomance in the learning of english as a foreing language is presented. these questions demand reflection and guide to know how to improve the learning strategies. some answers are given aimed at guiding students in the learning process and helping them to solve difficulties, since we cannot address every need or individual query. it is not intended to replace the role of the english professor
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