929 resultados para Three-wave processes


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In previous papers, the type-I intermittent phenomenon with continuous reinjection probability density (RPD) has been extensively studied. However, in this paper type-I intermittency considering discontinuous RPD function in one-dimensional maps is analyzed. To carry out the present study the analytic approximation presented by del Río and Elaskar (Int. J. Bifurc. Chaos 20:1185-1191, 2010) and Elaskar et al. (Physica A. 390:2759-2768, 2011) is extended to consider discontinuous RPD functions. The results of this analysis show that the characteristic relation only depends on the position of the lower bound of reinjection (LBR), therefore for the LBR below the tangent point the relation {Mathematical expression}, where {Mathematical expression} is the control parameter, remains robust regardless the form of the RPD, although the average of the laminar phases {Mathematical expression} can change. Finally, the study of discontinuous RPD for type-I intermittency which occurs in a three-wave truncation model for the derivative nonlinear Schrodinger equation is presented. In all tests the theoretical results properly verify the numerical data

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En este trabajo doctoral se evaluó la bioaccesibilidad in vitro para As, Co, Cr, Cu, Ni, Pb y Zn (en la fracción menor de 100μm) por tres procedimientos distintos en 32 muestras de suelo superficial, recogidas en 16 parques infantiles de la ciudad de Madrid.. Dos de los métodos de extracción (SBET y extracción con HCl a pH=1.5) reproducen únicamente la fase gástrica, mientras que otro (RIVM) tiene en cuenta un proceso completo de digestión (gástrico+intestinal). La bioaccesibilidad (%) se definió frente a las concentraciones pseudototales de los elementos traza estudiados (agua regia), utilizando un modelo de regresión lineal pasando por el origen. Los dos métodos gástricos ofrecieron resultados similares y consistentes con datos de otros estudios, siendo el orden de bioaccesibilidad As ≈ Cu ≈ Pb ≈ Zn > Co > Ni > Cr, con rangos entre el 63 y el 7%. Para el procedimiento RIVM (gástrico + intestinal) se obtuvieron valores de un orden similar a los obtenidos en fase gástrica para los elementos As, Cu, Pb y Zn (muy similares para el Zn, algo superiores para Cu y Pb, y algo inferiores para As). Por el contrario, la bioaccesibilidad de Co y Cu es, en este caso, muy superior a la resultante de los ensayos en fase gástrica. El orden de bioaccesibilidad es Co ≈ Cu ≈ Pb > As ≈ Cr ≈ Zn, con rangos entre el 42 y el 69%. Los resultados de los tres procedimientos evaluados correlacionan muy intensamente para los elementos traza As, Cu, Pb y Zn, existiendo intensas correlaciones entre casi todos los elementos estudiados para las dos fases gástricas, no siendo así en el ensayo de digestión completa. Se estudiaron algunas propiedades físico-químicas de los suelos muestreados, así como su composición en algunos elementos mayoritarios con el objeto de evaluar su influencia sobre la bioaccesibilidad. Se observa una dependencia de la bioaccesibilidad (%) de distintos elementos respecto a algunas propiedades de los suelos estudiados, tales como: contenido en Fe, Ca (carbonatos) y P, materia orgánica y pH. El contenido en Fe resulta ser muy relevante en cuanto a la bioaccesibilidad obtenida. En todos los casos correlaciona negativamente con el porcentaje de bioaccesibilidad siendo más significativo este fenómeno en el caso de las extracciones en fase gástrica. Se sugiere que dada la baja solubilización de los óxidos de hierro en los medios extractantes empleados hay una fuerte adsorción de complejos aniónicos (metal-anión cloruro) sobre la superficie de estos óxidos de Fe, con la consiguientes disminución de la bioaccesibilidad. En cuanto al contenido en calcio (carbonatos) este dato parece muy relevante si nos referimos a la bioaccesibilidad del As. Efectivamente el As aparece ligado al Ca del suelo y su solubilización en medios ácidos implicaría un aumento de la bioaccesibilidad del As, mientras que su precipitación al pasar a pH básico (fase intestinal) provocaría una disminución de la bioaccesibilidad. La materia orgánica sólo se ha demostrado relevante respecto a los contenidos pseudototales para el Zn. Para el porcentaje de bioaccesibilidad es significativo para muchos elementos en los ensayos en fase gástrica. La influencia del pH de los suelos estudiados sólo parece ser muy significativo en el caso del Cr. Los valores altamente homogéneos del pH de los suelos estudiados sin duda hacen que este parámetro no resulte significativo para más elementos, tal como se desprende de estudios anteriores. ABSTRACT A total of 32 samples of superficial soil were collected from 16 playground areas in Madrid. The in vitro bioaccessibility of As, Co, Cr, Ni, Pb and Zn (fraction below 100μm) was evaluated by means of three extraction processes. Two of them (SBET and HCl-extraction, pH=1.5) simulate the gastric enviroment, while the other one (RIVM) reproduces a gastric+intestinal digestion sequence. Bioaccessibility (%) was compared against pseudo-total concentrations of trace elements studied (aqua regia) with a linear regression model (forced to intercept the origin) Both gastric methods offered very similar and consistent results with data from other studies, with bioaccessibilities following the order: As ≈ Cu ≈ Pb ≈ Zn > Co > Ni > Cr, and ranging from 63% to 7% The values obtained through RIVM (gastric+ intestinal) method are similar to those obtained in gastric environment for elements: As, Cu, Pb and Zn (very similar to Zn, to a higher extent Cu and Pb, and to a lower extent As). On the contrary the bioaccessibility obtained for elements Co and Cu is considerable higher than in gastric environment sequence. Bioaccessibilities follows the order Co ≈ Cu ≈ Pb >As ≈ Cr ≈ Zn, ranging between 42 and 69%. The three procedures used correlate very intensively to trace elements As,Cu, Pb and Zn, existing strong correlations between almost all elements studied for the two gastric environment, not in the case of the complete digestion sequence. Some soil physical – chemical properties selected were studied, as well as their composition in some main elements in order to assess their influence on bioaccessibility. A dependence was observed between different elements bioaccesibility (%) and some soil properties, such as: Fe, Ca (carbonate) content and P, organic matter and pH. Fe content becomes very relevant regarding the bioaccessibility obtained. In all cases it correlated negatively with bioaccessibility percentage being more significant this phenomenon in gastric environment extractions. It is suggested that given the low solubility of iron oxide in the extractant media used there has to be a strong adsorption of anionic complexes (metal – chloride anion) on these Fe oxides surface, with a consequent decrease of bioaccessibility. Regarding calcium (carbonate) content this data seems very relevant referred to As bioaccessibility. Indeed, As appears to be bound to soil Ca and its solubilisation in acid media would increase As bioaccessibility, while its precipitation at basic pH (intestinal environment) would cause a reduction in bioaccessibility. The influence of organic matter only seemed significant for Zn “total” content, while it is significant in terms of gastric bioaccessibility for many elements. Soil pH only seems to be very significant in case of Cr. The highly homogeneous values for soil pH makes the influence of this parameter negligible for the other elements, unlike what has been observed in several previous studies.

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Aunque los conjuntos de vivienda social carecen en Europa de un nivel de protección patrimonial comparable a otras áreas urbanas, las negociaciones que surgen a raíz del anuncio de su remodelación o rehabilitación resultan inexplicables si no se supone su aceptación como patrimonio por parte de algunos de los actores implicados. Nos encontraríamos entonces no con un repertorio patrimonial consolidado, sino ante un proceso de patrimonialización, entendido no sólo como el paso de la categoría de no-patrimonio a la de patrimonio mediante la protección jurídica o urbanística, sino también como la construcción del consenso social suficiente en torno la posesión de ciertos valores preexistentes, así como la producción y reproducción social e histórica de estos valores. Ante el incipiente proceso de patrimonialización de determinados Barrios de Promoción Oficial madrileños, la tesis aborda dos cuestiones fundamentales, los mecanismos que conducen a su construcción social e histórica como nuevos elementos patrimoniales, y la evolución y estado actual del conjunto de elementos eventualmente patrimonializables, los Barrios de Promoción Oficial madrileños. De esta forma, propone un modelo teórico del proceso de patrimonialización de los conjuntos de vivienda social, basado en la identificación de discursos, valores, sujetos y etapas, así como de su relación con las características físicas y sociales originales de los barrios y su evolución hasta la actualidad. Para ello, se reconstruye la evolución física, social y de la protección patrimonial de los Barrios de Promoción Oficial madrileños, y se analizan tres procesos concretos de patrimonialización, la participación de la Colonia del Tercio y Terol en la defensa ciudadana de las Colonias Históricas madrileñas (1973-1979), la incorporación de criterios patrimoniales en la rehabilitación integral del Poblado Dirigido de Caño Roto (1991-2004), y la protección patrimonial como obstáculo para la remodelación de la U.V.A. de Hortaleza (2004-2015). ABSTRACT Comparatively speaking, few social housing estates are legally protected as cultural heritage in Europe. However, when a physical intervention is announced, the ensuing negotiation often defies explanation unless one assumes that the estate is regarded as cultural heritage by some of the players involved. Therefore, one should not so much talk of social housing as heritage, but of the process of patrimonialisation, which refers not only to the change of these estates from the status of non-heritage to that of cultural heritage through their legal recognition, but also to the process that leads to the acknowledgment of certain values in these estates, and even the social and cultural shaping of these values. This thesis tackles two main issues: the mechanisms that lead to the social and historical construction of new heritage elements or repertoires, and the evolution and current status of the Barrios de Promoción Oficial in Madrid. It proposes a theoretical model of the process of patrimonialisation of social housing estates, based on the identification of discourses, values, subjects and phases, as well as its relationship with the original physical and social features of these estates and their further evolution up to the present. In order to do so, the changes in the physical and social features of the Barrios de Promoción Oficial and in their heritage protection are reconstructed, and three particular processes are analysed. These are the role of Colonia del Tercio y Terol in the citizens’ movement for the preservation of the Colonias Históricas in Madrid (1973-1979), the incorporation of conservation criteria in the refurbishment of Poblado Dirigido de Caño Roto (1991-2004), and heritage as an obstacle to urban renewal in U.V.A. de Hortaleza (2004-2015).

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O argumento desta tese é que a lenta configuração social do racismo na província do Maranhão pode ser observada como uma consequência inesperada da combinação de três processos distintos entre si, dotados de causalidades e efeitos próprios, mas cujo amálgama histórico impulsou a valorização simbólica e política das classificações de cor como critério de distinção e controle social. Em primeiro lugar, o processo econômico de derrocada do setor de exportação, diretamente vinculado à plantation escravista em relação à produção voltada para o mercado interno. Em segundo lugar, o crescimento demográfico da população livre de cor no conjunto dos trabalhadores, grupo que se tornou majoritário ainda na primeira metade do século dezenove. Por fim, o lugar periférico do Estado do Maranhão na política brasileira desde o processo de independência. Para demonstrar esta tese analiso a combinação desses processos na cidade de São Luís do Maranhão e os impasses da integração da população negra nessa sociedade que se imaginou como uma Atenas brasileira.

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Animals from flies to humans adjust their development in response to environmental conditions through a series of developmental checkpoints, which alter the sensitivity of organs to environmental perturbation. Despite their importance, we know little about the molecular mechanisms through which this change in sensitivity occurs. Here we identify two phases of sensitivity to larval nutrition that contribute to plasticity in ovariole number, an important determinant of fecundity, in Drosophila melanogaster. These two phases of sensitivity are separated by the developmental checkpoint called "critical weight"; poor nutrition has greater effects on ovariole number in larvae before critical weight than after. We find that this switch in sensitivity results from distinct developmental processes. In precritical weight larvae, poor nutrition delays the onset of terminal filament cell differentiation, the starting point for ovariole development, and strongly suppresses the rate of terminal filament addition and the rate of increase in ovary volume. Conversely, in postcritical weight larvae, poor nutrition affects only the rate of increase in ovary volume. Our results further indicate that two hormonal pathways, the insulin/insulin-like growth factor and the ecdysone-signaling pathways, modulate the timing and rates of all three developmental processes. The change in sensitivity in the ovary results from changes in the relative contribution of each pathway to the rates of terminal filament addition and increase in ovary volume before and after critical weight. Our work deepens our understanding of how hormones act to modify the sensitivity of organs to environmental conditions, thereby affecting their plasticity.

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In this article we investigate voter volatility and analyze the causes and motives of switching vote intentions. We test two main sets of variables linked to volatility in literature; political sophistication and ‘political (dis)satisfaction’. Results show that voters with low levels of political efficacy tend to switch more often, both within a campaign and between elections. In the analysis we differentiate between campaign volatility and inter-election volatility and by doing so show that the dynamics of a campaign have a profound impact on volatility. The campaign period is when the lowly sophisticated switch their vote intention. Those with higher levels of interest in politics have switched their intention before the campaign has started. The data for this analysis are from the three wave PartiRep Belgian Election Study (2009).

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Thesis (Ph.D.)--University of Washington, 2016-06

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Plants are necessarily complex systems that require monitoring of multiple environmental signals and, in response to those signals, coordination of differentiation and development of an extensive array of cell types at multiple locations. This coordination must rely on integration of long-distance signals that provide a means of communication among different plant parts. We propose that the relatively well-characterized classical phytohormones must act with several other long-distance signals to achieve this level of organization with dynamic yet measured responses. This is supported by observations that classical phytohormones: (i) operate in complex yet experimentally unresolved networks involving cross-talk and feedback, (ii) are generally multifunctional and nonspecific and hence must rely on other long-distance cues or pre-set conditions to achieve specificity and (iii) are likely to mask roles of other long-distance signals in several experimental contexts. We present evidence for involvement of novel long-distance signals in three developmental processes-branching, flowering and nodulation, and discuss the possible identities of novel signalling molecules.

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Purpose - The purpose of this paper is to develop an integrated quality management model that identifies problems, suggests solutions, develops a framework for implementation and helps to evaluate dynamically healthcare service performance. Design/methodology/approach - This study used the logical framework analysis (LFA) to improve the performance of healthcare service processes. LFA has three major steps - problems identification, solution derivation, and formation of a planning matrix for implementation. LFA has been applied in a case-study environment to three acute healthcare services (Operating Room utilisation, Accident and Emergency, and Intensive Care) in order to demonstrate its effectiveness. Findings - The paper finds that LFA is an effective method of quality management of hospital-based healthcare services. Research limitations/implications - This study shows LFA application in three service processes in one hospital. This very limited population sample needs to be extended. Practical implications - The proposed model can be implemented in hospital-based healthcare services in order to improve performance. It may also be applied to other services. Originality/value - Quality improvement in healthcare services is a complex and multi-dimensional task. Although various quality management tools are routinely deployed for identifying quality issues in healthcare delivery, they are not without flaws. There is an absence of an integrated approach, which can identify and analyse issues, provide solutions to resolve those issues, develop a project management framework to implement those solutions. This study introduces an integrated and uniform quality management tool for healthcare services. © Emerald Group Publishing Limited.

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Purpose - The purpose of the paper is to develop an integrated quality management model, which identifies problems, suggests solutions, develops a framework for implementation and helps evaluate performance of health care services dynamically. Design/methodology/approach - This paper uses logical framework analysis (LFA), a matrix approach to project planning for managing quality. This has been applied to three acute healthcare services (Operating room utilization, Accident and emergency, and Intensive care) in order to demonstrate its effectiveness. Findings - The paper finds that LFA is an effective method of quality management of hospital-based healthcare services. Research limitations/implications - This paper shows LFA application in three service processes in one hospital. However, ideally this is required to be tested in several hospitals and other services as well. Practical implications - In the paper the proposed model can be practised in hospital-based healthcare services for improving performance. Originality/value - The paper shows that quality improvement in healthcare services is a complex and multi-dimensional task. Although various quality management tools are routinely deployed for identifying quality issues in health care delivery and corrective measures are taken for superior performance, there is an absence of an integrated approach, which can identify and analyze issues, provide solutions to resolve those issues, develop a project management framework (planning, monitoring, and evaluating) to implement those solutions in order to improve process performance. This study introduces an integrated and uniform quality management tool. It integrates operations with organizational strategies. © Emerald Group Publishing Limited.

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During the early stages of employment, newly hired employees find out what their new organisations are like. Their first impressions are extremely important in determining the course of subsequent attitudes and behaviour. Recently, a considerable progress has been made towards the understanding of adjustment process, however, the literature remain divided along a number of fronts. Moreover, newcomer research has been conducted independent and irrespective of newcomer personality individual differences. This seems to be a critical oversight because there is overlap in predictions involving these constructs. The current research extended the previous one by examining these multiple antecedents, including Big Five personality traits of newcomer to the tandem process of adjustment as well as outcomes that immediate, or ?proximal? to the process of newcomer adjustment. Following a cross sectional pilot study of recent college graduate, a three- wave longitudinal study of newcomers in seven organisations examined Big Five personality traits, proactive behaviour, and socialisation influence (formal training, leaders, co-workers) as antecedents of proximal adjustment outcomes (group integration, political knowledge of organisation, and task performance). The main study results suggested that personality traits were related to proximal adjustment outcomes, specifically, Conscientiousness was positively related to all proximal adjustment outcomes. Openness to experience was related to task performance and political knowledge. Group integration is independently related to Agreeableness, Extraversion and Neuroticism. The socialisation influence moderate these relations, for example, leader socialisation moderate Conscientiousness as it relates to political knowledge and group integration, while co-worker moderate Extraversion as it relates to task performance. Finally, it was found that, the relationship between proximal adjustment outcomes and the personality dimensions Openness was mediated by proactive behaviour. Overall, the results suggested that individual differences have a role in newcomer adjustment as it facilitate the socialisation influence, and Big Five was one of the key determinants of newcomer adjustment.

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Background: Although pregnancy loss is a distressing health event for many women, research typically equates women’s experiences of pregnancy loss to ‘married heterosexual women’s experiences of pregnancy loss’. The objective of this study was to explore lesbian and bisexual women’s experiences of miscarriage, stillbirth and neonatal death. Methods: This study analysed predominantly qualitative online survey data from 60 non-heterosexual, mostly lesbian, women from the UK, USA, Canada and Australia. All but one of the pregnancies was planned. Most respondents had physically experienced one early miscarriage during their first pregnancy, although a third had experienced multiple losses. Results: The analysis highlights three themes: processes and practices for conception; amplification of loss; and health care and heterosexism. Of the respondents, 84% conceived using donor sperm; most used various resources to plan conception and engaged in preconception health care. The experience of loss was amplified due to contextual factors and the investment respondents reported making in impending motherhood. Most felt that their loss(es) had made a ‘significant’/‘very significant’ impact on their lives. Many respondents experienced health care during their loss. Although the majority rated the overall standard of care as ‘good’/‘very good’/‘outstanding’, a minority reported experiencing heterosexism from health professionals. Conclusions: The implications for policy and practice are outlined. The main limitation was that the inflexibility of the methodology did not allow the specificities of women’s experiences to be probed further. It is suggested that both coupled and single non-heterosexual women should be made more visible in reproductive health and pregnancy loss research.

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Chronic exposure to aluminium (Al) remains a controversial possible cause of sporadic forms of Alzheimer's disease (AD). This article reviews the evidence that once Al enters the brain and individual brain cells, it may be involved in three pathological processes: (1) the production of abnormal forms of tau leading to the formation of cellular neurofibrillary tangles and neuropil threads; (2) the processing of the amyloid precursor protein, resulting in the formation of beta-amyloid deposits and senile plaques, and (3) that via the mutual histocompatibility system, Al could be involved in the initiation of the immune response observed in AD patients. Despite recent evidence that Al could be involved in these processes, a conclusive case that exposure to Al initiates the primary pathological process in sporadic AD remains to be established.

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Guided by theory in both the trust and leadership domains, the overarching aim of this thesis was to answer a fundamental question. Namely, how and when does trust-building between leaders and followers enhance leader-member exchange (LMX) development and organisational trust? Although trust is considered to be at the crux of the leader-follower relationship, surprisingly little theoretical or empirical attention has been devoted to understanding the precise nature of this relationship. By integrating both a typology of trustworthy behaviour and a process model of trust development with LMX theory, study one developed and tested a new model of LMX development with leader-follower trust-building as the primary mechanism. In a three wave cross-lagged design, 294 student dyads in a business simulation completed measures of trust perceptions and LMX across the first 6 months of the LMX relationship. Trust-building was found to account for unexplained variance in the LMX construct over time, while controlling for initial relationship quality, thus confirming the critical role of the trust-building process in LMX development. The strongest evidence was found for the role of integrity-based trust-building behaviour, albeit only when such behaviour was not attributed to insincere motives. The results for ability and benevolence-based trustworthy behaviour revealed valued insights into the developmental nature of trustworthiness perceptions within LMX relationships. Thus, the pattern of results in study one provided a more comprehensive and nuanced understanding of the dynamic interplay between trust and LMX. In study two, leader trust-building was investigated cross-sectionally within an organisational sample of 201 employees. The central aim of this study was to investigate whether leader trust-building within leader-follower relationships could be leveraged for organisational trust. As expected, the trust-building process instigated by members in study one was replicated for leaders in study two. In addition, the results were most consistent for benevolence-based trust building, whereas both integrity- and ability-based trust-building were moderated by the position of the leader within the organisation’s hierarchy. Overall, the findings of this thesis shed considerable light on the richness of trusting perceptions in organisations, and the critical role of trust-building in LMX development and organisational trust.

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The microstructural stability of aluminide diffusion coatings, prepared by means of a two-stage pack-aluminization treatment on single-crystal nickel-base superalloy substrates, is considered in this article. Edge-on specimens of coated superalloy are studied using transmission electron microscopy (TEM). The effects of coating thickness and post-coating heat treatment (duration, temperature, and atmosphere) on coating microstructure are examined. The article discusses the partial transformation of the matrix of the coating, from a B2-type phase (nominally NiAl) to a L12 phase (nominally Ni3(Al, Ti)), during exposure at temperatures of 850 °C and 950 °C in air and in vacuum for up to 138 hours. Three possible processes that can account for decom- position of the coating matrix are investigated, namely, interdiffusion between the coating and the substrate, oxidation of the coating surface, and aging of the coating. Of these processes, aging of the coating is shown to be the predominant factor in the coating transformation under the conditions considered. © 1992 The Minerals, Metals and Materials Society, and ASM International.