978 resultados para internal structure


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A multi-variate descriptive model of environmental and nature conservation attitudes and values is proposed and empirically supported. A mapping sentence is developed out of analysis of data from a series of Repertory Grid interviews addressing conservation employees' attitudes towards their profession's activities. The research is carried out within the meta-theoretical framework of Facet Theory. A mapping sentence is developed consisting of 9 facets. From the mapping sentence 3 questionnaires were constructed viewing the selective orientations towards environmental concern. A mapping sentence and facet model is developed for each study. Once the internal structure of this model had been established using Similarity Structure Analysis, the elements of the facets are subjected to Partial Order Scalogram Analysis with base coordinates. A questionnaire was statistically analysed to assess the relationship between facet elements and 4 measures of attitudes towards, and involvement with, conservation. This enabled the comparison of the relative strengths of attitudes associated with each facet element and each measure of conservation attitude. In general, the relationship between the social value of conservation and involvement pledges to conservation were monotonic; perceived importance of a conservation issue appearing predictive of personal involvement. Furthermore, the elements of the life area and scale facets were differentially related to attitude measures. The multi-variate descriptive model of environmental conservation values and attitudes is discussed in relation to its implications for psychological research into environmental concern and for environmental and nature conservation.

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The problems associated with x-ray-transparent denture base are defined and conventional approaches to their solution are assessed. Consideration of elemental absorption parameters leads to the postulation that atoms such as zinc, and bromine, may be effective radiopacifiers over at least part of the clinical x-ray spectrum. These elements had hitherto been considered too light to be effective. Investigation of copolymers of methylmethacrylate and p-bromostyrene revealed no deleterious effects arising from the aromatically brominated monomer (aliphatic bromination caused UV destabilisation). For effective x-ray absorption a higher level of bromination would be necessary, but the expense of suitable compounds made further study unjustifiable. Incorporation of zinc atoms into the polymer was accomplished by copolymerisation of zinc acrylate with methylmethacrylate in solution. At high zinc levels this produced a powder copolymer convenient for addition to dental polymers in the dough moulding process. The resulting mouldings showed increasing brittleness at high loadings of copolymer. Fracture was shown to be through the powder particles rather than around them, indicating the source of weakness to be in the internal structure of the copolymer. The copolymer was expected to be cross-linked through divalent zinc ions and its insolubility and infusibility supported this. Cleavage of the ionic cross links with formic acid produced a zinc-free linear copolymer of high molecular weight. Addition of low concentrations of acrylic acid to the dough moulding monomer appeared to 'labilise' the cross links producing a more homogeneous moulding with adequate wet strength. Toxicologically the zinc-containing materials are satisfactory and though zinc is extracted at a measurable rate in an aqueous system, this is very small and should be acceptable over the life of a denture. In other respects the composite is quite satisfactory and though a marketable product is not claimed the system is considered worthy of further study.

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Gelatin is a principal excipient used as a binder in the formulation of lyophilized orally disintegrating tablets. The current study focuses on exploiting the physicochemical properties of gelatin by varying formulation parameters to determine their influence on orally disintegrating tablet (ODT) characteristics. Process parameters, namely pH and ionic strength of the formulations, and ball milling were investigated to observe their effects on excipient characteristics and tablet formation. The properties and characteristics of the formulations and tablets which were investigated included: glass transition temperature, wettability, porosity, mechanical properties, disintegration time, morphology of the internal structure of the freeze-dried tablets, and drug dissolution. The results from the pH study revealed that adjusting the pH of the formulation away from the isoelectric point of gelatin, resulted in an improvement in tablet disintegration time possibly due to increase in gelatin swelling resulting in greater tablet porosity. The results from the ionic strength study revealed that the inclusion of sodium chloride influenced tablet porosity, tablet morphology and the glass transition temperature of the formulations. Data from the milling study showed that milling the excipients influenced formulation characteristics, namely wettability and powder porosity. The study concludes that alterations of simple parameters such as pH and salt concentration have a significant influence on formulation of ODT. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

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The morphology of asphalt mixture can be defined as a set of parameters describing the geometrical characteristics of its constituent materials, their relative proportions as well as spatial arrangement in the mixture. The present study is carried out to investigate the effect of the morphology on its meso- and macro-mechanical response. An analysis approach is used for the meso-structural characterisation based on the X-ray computed tomography (CT) data. Image processing techniques are used to systematically vary the internal structure to obtain different morphology structures. A morphology framework is used to characterise the average mastic coating thickness around the main load carrying structure in the structures. The uniaxial tension simulation shows that the mixtures with the lowest coating thickness exhibit better inter-particle interaction with more continuous load distribution chains between adjacent aggregate particles, less stress concentrations and less strain localisation in the mastic phase.

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Pt catalyst series were prepared on mesoporous SBA-15, SBA-16, KIT-6, true liquidcrystal-templated meso-macroporous SBA-15 and a commercial, low surface area silicasupport. Support structure can be easily fabricated using surfactant templating as a mode ofstringent control on porosity, surface area and internal structure. The impact of varying Pt-support physicochemical properties was systematically studied for the selective transformation of allylic substrates under chemoselective oxidation and hydrogenation regimes, a class of reactions highly applicable to industry. Pt-based heterogeneous catalysts are well-known for their utilisation in the hydrogenation of α,β-unsaturated aldehydes,although the mode of action and lack of systematic studies in the literature fuels continuing debate into the role of Pt nanoparticles and support choice for this area. This project attempts to shed some light on several frequently asked questions in this field. Successful support synthesis and stability after Pt impregnation is confirmed through HRTEM, XRD and N2 porosimetry. Decreasing metal loading promoted dispersion values,regardless of support choice, with surface PtO2 content also showing visible enhancement.Increasing support surface area and mesoporosity exhibited the following trend on Pt dispersion augmentation; low surface area commercial silica < true liquid crystal-templated SBA-15 < SBA-15 < SBA-16 ~ KIT-6. For the selective oxidation of cinnamyl alcohol,increasing PtO2 surface population confers substantial rate enhancements, with turnover frequencies evidencing PtO2 to be the active species .In the Pt-catalysed hydrogenation of cinnamaldehyde, strong support insensitivity was observed towards catalytic activity; as turnover frequencies normalised to Pt metal reveal constant values. However, structure sensitivity to the desired unsaturated alcohol arose,evidencing the requirement of flat, extended Pt (111) facets for C=O hydrogenation. Pt/SBA-15 proved the most selective, reflecting suppressed cinnamyl alcohol hydrogenation, with DRIFTS and in-situ ATR-IR evidencing the key role of support polarity in re-orientation of cinnamaldehyde to favour di-σCO adsorption and C=O versus C=C hydrogenation. High pressures increased activity, whilst a dramatic shift in selectivity from dominant C=C (1 bar)to C=O hydrogenation (10 bar) was also observed, attributed to surface crowding and suppression of di-σCC and η4 di-σCO+πC=C cinnamaldehyde binding modes.

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An inverse turbulent cascade in a restricted two-dimensional periodic domain creates a condensate—a pair of coherent system-size vortices. We perform extensive numerical simulations of this system and carry out theoretical analysis based on momentum and energy exchanges between the turbulence and the vortices. We show that the vortices have a universal internal structure independent of the type of small-scale dissipation, small-scale forcing, and boundary conditions. The theory predicts not only the vortex inner region profile, but also the amplitude, which both perfectly agree with the numerical data.

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This study explored the strategies that community-based, consumer-focused advocacy, alternative service organizations (ASOs), implemented to adapt to the changes in the nonprofit funding environment (Oliver & McShane, 1979; Perlmutter, 1988a, 1994). It is not clear as to the extent to which current funding trends have influenced ASOs as little empirical research has been conducted in this area (Magnus, 2001; Marquez, 2003; Powell, 1986). ^ This study used a qualitative research design to investigate strategies implemented by these organizations to adapt to changes such as decreasing government, foundation, and corporate funding and an increasing number of nonprofit organizations. More than 20 community informants helped to identify, locate, and provide information about ASOs. Semi-structured interviews were conducted with a sample of 30 ASO executive directors from diverse organizations in Miami-bade and Broward Counties, in South Florida. ^ Data analysis was facilitated by the use of ATLAS.ti, version 5, a qualitative data analysis computer software program designed for grounded theory research. This process generated five major themes: Funding Environment; Internal Structure; Strategies for Survival; Sustainability; and Committing to the Cause, Mission, and Vision. ^ The results indicate that ASOs are struggling to survive financially by cutting programs, decreasing staff, and limiting service to consumers. They are also exploring ways to develop fundraising strategies; for example, increasing the number of proposals written for grants, focusing on fund development, and establishing for-profit ventures. Even organizations that state that they are currently financially stable are concerned about their financial vulnerability. There is little flexibility or cushioning to adjust to "funding jolts." The fear of losing current funding levels and being placed in a tenuous financial situation is a constant concern for these ASOs. ^ Further data collected from the self-administered Funding Checklist and demographic forms were coded and analyzed using Statistical Package for the Social Sciences (SPSS). Descriptive information and frequencies generated findings regarding the revenue, staff compliment, use of volunteers and fundraising consultants, and fundraising practices. The study proposes a model of funding relationships and presents implications for social work practice, and policy, along with recommendations for future research. ^

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A Mediation System utilizes a central security mediator that is primarily concerned with securing the internal structure of the Mediation System. The current problem is that clients are unable to have authority and administrative rights over the security of their data during a transaction. In addition, this Mediation System is unsuited in presenting a metric that measures the level of confidence of security access rights. This creates a black-box perspective from the client towards the Mediation System and also gives no assurance to these clients that they have assigned the proper security access rights that reflect the current environment of the mediation system. This dissertation presents a Collaborative Information System (CIS) that uses an agent based approach to encapsulate collaborative information and security policies within the Mediation System which are under the control of the clients of the Mediation System. In conjunction with the CIS's Stochastic Security Framework it is possible to take a probabilistic approach in modeling the security access rights of a collaboration transaction. The research results showed that it is feasible to construct a Mediation System utilizing agents and stochastic equations to establish an environment where the client has authority and administrative control in assigning security access rights to their collaborative data that can establish a metric that measures the level of confidence of these assigned rights.

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This dissertation consists of four studies examining two constructs related to time orientation in organizations: polychronicity and multitasking. The first study investigates the internal structure of polychronicity and its external correlates in a sample of undergraduate students (N = 732). Results converge to support a one-factor model and finds measures of polychronicity to be significantly related to extraversion, agreeableness, and openness to experience. The second study quantitatively reviews the existing research examining the relationship between polychronicity and the Big Five factors of personality. Results reveal a significant relationship between extraversion and openness to experience across studies. Studies three and four examine the usefulness of multitasking ability in the prediction of work related criteria using two organizational samples (N = 175 and 119, respectively). Multitasking ability demonstrated predictive validity, however the incremental validity over that of traditional predictors (i.e., cognitive ability and the Big Five factors of personality) was minimal. The relationships between multitasking ability, polychronicity, and other individual differences were also investigated. Polychronicity and multitasking ability proved to be distinct constructs demonstrating differential relationships with cognitive ability, personality, and performance. Results provided support for multitasking performance as a mediator in the relationship between multitasking ability and overall job performance. Additionally, polychronicity moderated the relationship between multitasking ability and both ratings of multitasking performance and overall job performance in Study four. Clarification of the factor structure of polychronicity and its correlates will facilitate future research in the time orientation literature. Results from two organizational samples point to work related measures of multitasking ability as a worthwhile tool for predicting the performance of job applicants.

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The electromagnetic form factors are the most fundamental observables that encode information about the internal structure of the nucleon. The electric (GE) and the magnetic ( GM) form factors contain information about the spatial distribution of the charge and magnetization inside the nucleon. A significant discrepancy exists between the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors of the proton. One possible explanation for the discrepancy is the contributions of two-photon exchange (TPE) effects. Theoretical calculations estimating the magnitude of the TPE effect are highly model dependent, and limited experimental evidence for such effects exists. Experimentally, the TPE effect can be measured by comparing the ratio of positron-proton elastic scattering cross section to that of the electron-proton [R = σ(e +p)/σ(e+p)]. The ratio R was measured over a wide range of kinematics, utilizing a 5.6 GeV primary electron beam produced by the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This dissertation explored dependence of R on kinematic variables such as squared four-momentum transfer (Q2) and the virtual photon polarization parameter (&epsis;). A mixed electron-positron beam was produced from the primary electron beam in experimental Hall B. The mixed beam was scattered from a liquid hydrogen (LH2) target. Both the scattered lepton and the recoil proton were detected by the CEBAF Large Acceptance Spectrometer (CLAS). The elastic events were then identified by using elastic scattering kinematics. This work extracted the Q2 dependence of R at high &epsis;(&epsis; > 0.8) and the $&epsis; dependence of R at ⟨Q 2⟩ approx 0.85 GeV2. In these kinematics, our data confirm the validity of the hadronic calculations of the TPE effect by Blunden, Melnitchouk, and Tjon. This hadronic TPE effect, with additional corrections contributed by higher excitations of the intermediate state nucleon, largely reconciles the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors.

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Radiolarians in the Arctic Ocean have been studied lately in both plankton and sediment trap samples in the Chukchi Sea area. These studies have shed light on new radiolarian taxa, especially within the order Entactinaria, including two new species of Joergensenium, Joergensenium arcticum from the western Arctic Ocean, so far restricted to the Pacific Winter Water in the Chukchi Sea, and Joergensenium clevei hitherto found in the northern part of the Norwegian Sea south of the Fram Strait. The taxonomic position of the order Entactinaria is discussed and the genus Joergensenium has been emended. We have also observed in detail the internal structure of J. arcticum using Microfocus X-ray Computed Tomography and have utilized three-dimensional imaging for the first time in a species description.

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Twenty-four manganese nodules from the surface of the sea floor and fifteen buried nodules were studied. With three exceptions, the nodules were collected from the area covered by Valdivia Cruise VA 04 some 1200 nautical miles southeast of Hawaii. Age determinations were made using the ionium method. In order to get a true reproduction of the activity distribution in the nodules, they were cut in half and placed for one month on nuclear emulsion plates to determine the alpha-activity of the ionium and its daughter products. Special methods of counting the alpha-tracks resolution to depth intervals of 0.125 mm. For the first time it was possible to resolve zones of rapid growth (impulse growth) with growth rates, s > 50 mm/106 yr and interruptions in growth. With few exceptions the average rate of growth of all nodules was surprisingly uniform at 4-9 mm/10 yr. No growth could be recognized radioactively in the buried nodules. One exceptional nodule has had recent impulse growth and, in the material formed, the ionium is not yet in equilibrium with its daughter products. Individual layers in one nodule from the Indian Ocean could be dated and an average time interval of t = 2600±400 yr was necessary to form one layer. The alternation between iron and manganese-rich parts of the nodules was made visible by colour differences resulting from special treatment of cut surfaces with HCl vapour. The zones of slow growth of one nodule are relatively enriched in iron. Earlier attempts to find paleomagnetic reversals in manganese nodules have been continued. Despite considerable improvement in areal resolution, reversals were not detected in the nodules studied. Comparisons of the surface structure, microstructure in section and the radiometric dating show that there are erosion surfaces and growth surfaces on the outer surfaces of the manganese nodules. The formation of cracks in the nodules was studied in particular. The model of age-dependent nodule shrinkage and cracking surprisingly indicates that the nodules break after exceeding a certain age and/or size. Consequently, the breaking apart of manganese nodules is a continuous process not of catastrophic or discontinuous origin. The microstructure of the nodules exhibits differences in the mechanism of accretion and accretion rate of material, shortly referred to as accretion form. Thus non-directional growth inside the nodules as well as a directional growth may be observed. Those nodules with large accretion forms have grown faster than smaller ones. Consequently, parallel layers indicate slow growth. The upper surfaces of the nodules, protruding into the bottom water appear to be more prone to growth disturbances than the lower surfaces, immersed in the sediment. Features of some nodules show, that as they develop, they neither turned nor rolled. Yet unknown is the mechanism that keeps the nodules at the surface during continuous sedimentation. All in all, the nodules remain the objects of their own distinctive problems. The hope of using them as a kind of history book still seems to be very remote.

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Voice disorders (VD) in the elderly can interfere negatively in communication, emotional well-being and quality of life, conditions that correspond to greater exposure to illness and social isolation bringing consequent economic impact for the health system. It is assumed that institutionalized confinement, weakness and morbidity associated to nursing home (NH) contribute to transform VD an especially prevalent condition in institutionalized elderly, including those without cognitive impairment. Thus, the aim of this study was to determine the prevalence and associated factors of VD in NH elderly residents without cognitive impairment. There is no epidemiological diagnostic instruments of VD for elderly populations, so the first step of this study was dedicated to prepare and analyze the psychometric properties of a short, inexpensive and easy to use questionnaire named Screening for Voice Disorders in Older Adults (Rastreamento de Alterações Vocais em Idosos—RAVI). The methodological procedures of this step followed the guidelines of the Standards for Educational and Psychological Testing and contemplated validity evidence based on test content, based on response processes, based on internal structure and based on relations with other variables, as well as reliability analysis and clinical consistency. The result of the validation process showed that the RAVI final score generate valid and reliable interpretations for the epidemiological diagnosis of VD in the elderly, which endorsed the use of the questionnaire in the second stage of the study, performed in ten NH located in the city of Natal, Rio Grande do Norte. At this stage, data from socioeconomic and demographic variables, lifestyle, general health conditions and characterization of the institution were collected. It was performed a bivariate analysis and it was calculated the prevalence ratio as a magnitude association measure, with a confidence interval of 95%. The variables with p-value less than 0.20 were included in the multiple logistic regression model that followed the Forward selection method. The odds ratio found in the multivariate model was converted into prevalence ratio and the level of significance was 5%. The sample consisted of 117 subjects with predominance of females and average of 79.68 (± 7.92) years old. The prevalence of VD was 39.3% (95% CI: 30.4-48.1%). The multivariate model showed statistically significant association between VD and depressive symptoms, smoking for a year or more and selfreported hearing loss. In conclusion, VD is a prevalent health condition in NH elderly residents without cognitive impairment and is associated with factors involving psychosocial, lifestyle and communicative disability that require attention of managers and professionals involved with NH environment. Strategies to encourage communication and social integration, actions to combat smoking and minimizing the effects of hearing loss could stimulate the physical well-being, emotional and mental health of institutionalized elderly population, contributing to the vocal and communicative maintenance, a more effective social inclusion and better overall health condition.

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A set of methods has been used for studying composition, structure and distribution of Fe-Mn-micronodules in bottom sediments of the Northeast Pacific. It has been shown that there are two types of Fe-Mn micronodules differing in size, external shape, internal structure and composition of constituent manganese minerals.

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Le but de cette thèse est d’explorer le potentiel sismique des étoiles naines blanches pulsantes, et en particulier celles à atmosphères riches en hydrogène, les étoiles ZZ Ceti. La technique d’astérosismologie exploite l’information contenue dans les modes normaux de vibration qui peuvent être excités lors de phases particulières de l’évolution d’une étoile. Ces modes modulent le flux émergent de l’étoile pulsante et se manifestent principalement en termes de variations lumineuses multi-périodiques. L’astérosismologie consiste donc à examiner la luminosité d’étoiles pulsantes en fonction du temps, afin d’en extraire les périodes, les amplitudes apparentes, ainsi que les phases relatives des modes de pulsation détectés, en utilisant des méthodes standards de traitement de signal, telles que des techniques de Fourier. L’étape suivante consiste à comparer les périodes de pulsation observées avec des périodes générées par un modèle stellaire en cherchant l’accord optimal avec un modèle physique reconstituant le plus fidèlement possible l’étoile pulsante. Afin d’assurer une recherche optimale dans l’espace des paramètres, il est nécessaire d’avoir de bons modèles physiques, un algorithme d’optimisation de comparaison de périodes efficace, et une puissance de calcul considérable. Les périodes des modes de pulsation de modèles stellaires de naines blanches peuvent être généralement calculées de manière précise et fiable sur la base de la théorie linéaire des pulsations stellaires dans sa version adiabatique. Afin de définir dans son ensemble un modèle statique de naine blanche propre à l’analyse astérosismologique, il est nécessaire de spécifier la gravité de surface, la température effective, ainsi que différents paramètres décrivant la disposition en couche de l’enveloppe. En utilisant parallèlement les informations obtenues de manière indépendante (température effective et gravité de surface) par la méthode spectroscopique, il devient possible de vérifier la validité de la solution obtenue et de restreindre de manière remarquable l’espace des paramètres. L’exercice astérosismologique, s’il est réussi, mène donc à la détermination précise des paramètres de la structure globale de l’étoile pulsante et fournit de l’information unique sur sa structure interne et l’état de sa phase évolutive. On présente dans cette thèse l’analyse complète réussie, de l’extraction des fréquences à la solution sismique, de quatre étoiles naines blanches pulsantes. Il a été possible de déterminer les paramètres structuraux de ces étoiles et de les comparer remarquablement à toutes les contraintes indépendantes disponibles dans la littérature, mais aussi d’inférer sur la dynamique interne et de reconstruire le profil de rotation interne. Dans un premier temps, on analyse le duo d’étoiles ZZ Ceti, GD 165 et Ross 548, afin de comprendre les différences entre leurs propriétés de pulsation, malgré le fait qu’elles soient des étoiles similaires en tout point, spectroscopiquement parlant. L’analyse sismique révèle des structures internes différentes, et dévoile la sensibilité de certains modes de pulsation à la composition interne du noyau de l’étoile. Afin de palier à cette sensibilité, nouvellement découverte, et de rivaliser avec les données de qualité exceptionnelle que nous fournissent les missions spatiales Kepler et Kepler2, on développe une nouvelle paramétrisation des profils chimiques dans le coeur, et on valide la robustesse de notre technique et de nos modèles par de nombreux tests. Avec en main la nouvelle paramétrisation du noyau, on décroche enfin le ”Saint Graal” de l’astérosismologie, en étant capable de reproduire pour la première fois les périodes observées à la précision des observations, dans le cas de l’étude sismique des étoiles KIC 08626021 et de GD 1212.