946 resultados para Three-state Potts model


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Regional climate change projections for the last half of the twenty-first century have been produced for South America, as part of the CREAS (Cenarios REgionalizados de Clima Futuro da America do Sul) regional project. Three regional climate models RCMs (Eta CCS, RegCM3 and HadRM3P) were nested within the HadAM3P global model. The simulations cover a 30-year period representing present climate (1961-1990) and projections for the IPCC A2 high emission scenario for 2071-2100. The focus was on the changes in the mean circulation and surface variables, in particular, surface air temperature and precipitation. There is a consistent pattern of changes in circulation, rainfall and temperatures as depicted by the three models. The HadRM3P shows intensification and a more southward position of the subtropical Pacific high, while a pattern of intensification/weakening during summer/winter is projected by the Eta CCS/RegCM3. There is a tendency for a weakening of the subtropical westerly jet from the Eta CCS and HadRM3P, consistent with other studies. There are indications that regions such of Northeast Brazil and central-eastern and southern Amazonia may experience rainfall deficiency in the future, while the Northwest coast of Peru-Ecuador and northern Argentina may experience rainfall excesses in a warmer future, and these changes may vary with the seasons. The three models show warming in the A2 scenario stronger in the tropical region, especially in the 5A degrees N-15A degrees S band, both in summer and especially in winter, reaching up to 6-8A degrees C warmer than in the present. In southern South America, the warming in summer varies between 2 and 4A degrees C and in winter between 3 and 5A degrees C in the same region from the 3 models. These changes are consistent with changes in low level circulation from the models, and they are comparable with changes in rainfall and temperature extremes reported elsewhere. In summary, some aspects of projected future climate change are quite robust across this set of model runs for some regions, as the Northwest coast of Peru-Ecuador, northern Argentina, Eastern Amazonia and Northeast Brazil, whereas for other regions they are less robust as in Pantanal region of West Central and southeastern Brazil.

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The correlation between the breaks in the metallicity distribution and the corotation radius of spiral galaxies has been already advocated in the past and is predicted by a chemodynamical model of our Galaxy that effectively introduces the role of spiral arms in the star formation rate. In this work, we present photometric and spectroscopic observations made with the Gemini Telescope for three of the best candidates of spiral galaxies to have the corotation inside the optical disc: IC 0167, NGC 1042 and NGC 6907. We observed the most intense and well-distributed H ii regions of these galaxies, deriving reliable galactocentric distances and oxygen abundances by applying different statistical methods. From these results, we confirm the presence of variations in the gradients of metallicity of these galaxies that are possibly correlated with the corotation resonance.

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The three poikilophydric and homoiochlorophyllous moss species Campylopus savannarum (C. Muell.) Mitt., Racocarpus fontinaloides (C. Muell.) Par. and Ptychomitrium vaginatum Besch. grow on sun-exposed rocks of a tropical inselberg in Brazil subject to regular drying and wetting cycles. Effective photo-oxidative protection in the light-adapted desiccated state in all three species is achieved by a reduction of ground chlorophyll fluorescence, F, to almost zero. Upon rewatering, the kinetics of the recovery of F in air dry cushions to higher values is very fast in the first 5min, but more than 80min are needed until an equilibrium is reached gradually. The kinetics were not different between the three species. The three moss species, have a distinct niche occupation and form a characteristic zonation around soil vegetation islands on the rock outcrops, where C. savannarum and R. fontinaloides form an inner and outer belt, respectively, around vegetation islands and P vaginatum occurs as small isolated cushions on bare rock. However, they were not distinguished by the reduction of F in the dry state and the rewetting recovery kinetics and only slightly different in their photosynthetic capacity. Stable isotope ratios (delta C-13, delta N-15) indicate that liquid films of water limiting diffusion of CO2 are important in determining carbon acquisition and suggest that limitation of CO2 fixation by water films must be more pronounced over time in P vaginatum than in the latter species. This is determined by both the micro site occupied and the form of the moss cushions. (c) 2007 Elsevier GmbH. All rights reserved.

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Attention is a critical mechanism for visual scene analysis. By means of attention, it is possible to break down the analysis of a complex scene to the analysis of its parts through a selection process. Empirical studies demonstrate that attentional selection is conducted on visual objects as a whole. We present a neurocomputational model of object-based selection in the framework of oscillatory correlation. By segmenting an input scene and integrating the segments with their conspicuity obtained from a saliency map, the model selects salient objects rather than salient locations. The proposed system is composed of three modules: a saliency map providing saliency values of image locations, image segmentation for breaking the input scene into a set of objects, and object selection which allows one of the objects of the scene to be selected at a time. This object selection system has been applied to real gray-level and color images and the simulation results show the effectiveness of the system. (C) 2010 Elsevier Ltd. All rights reserved.

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This work presents a finite difference technique for simulating three-dimensional free surface flows governed by the Upper-Convected Maxwell (UCM) constitutive equation. A Marker-and-Cell approach is employed to represent the fluid free surface and formulations for calculating the non-Newtonian stress tensor on solid boundaries are developed. The complete free surface stress conditions are employed. The momentum equation is solved by an implicit technique while the UCM constitutive equation is integrated by the explicit Euler method. The resulting equations are solved by the finite difference method on a 3D-staggered grid. By using an exact solution for fully developed flow inside a pipe, validation and convergence results are provided. Numerical results include the simulation of the transient extrudate swell and the comparison between jet buckling of UCM and Newtonian fluids.

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The structure of laser glasses in the system (B(2)O(3))(0.6){(Al(2)O(3))(0.4-x)(Y(2)O(3))(x)} (0.1 <= x <= 0.25) has been investigated by means of (11)B, (27)Al, and (89)Y solid state NMR as well as Y-3d core-level X-ray photoelectron spectroscopy, (11)B magic-angle spinning (MAS) NMR spectra reveal that the majority of the boron atoms are three-coordinated, and a slight increase of four-coordinated boron content with increasing x can be noticed. (27)Al MAS NMR spectra show that the alumina species are present in the coordination states four, five and six. All of them are in intimate contact with both the three- and the four-coordinate boron species and vice versa, as indicated by (11)B/(27)Al rotational echo double resonance (REDOR) data. These results are consistent with the formation of a homogeneous, nonsegregated glass structure. For the first time, (89)Y solid state NMR has been used to probe the local environment of Y(3+) ions in a glass-forming system. The intrinsic sensitivity problem associated with (89)Y NMR has been overcome by combining the benefits of paramagnetic doping with those of signal accumulation via Carr-Purcell spin echo trains. Both the (89)Y chemical shifts and the Y-3d core level binding energies are found to be rather sensitive to the yttrium bonding state and reveal that the bonding properties of the yttrium atoms in these glasses are similar to those found in the model compounds YBO(3) and YAl(3)(BO(3))(4), Based on charge balance considerations as well as (11)B NMR line shape analyses, the dominant borate species are concluded to be meta- and pyroborate anions.

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This thesis examines the bilateral trade between Vietnam and twenty three European countries based on a gravity model and panel data for years 1993 to 2004. Estimates indicate that economic size, market size and real exchange rate of Vietnam and twenty three European countries play major role in bilateral trade between Vietnam and these countries. Distance and history, however, do not seem to drive the bilateral trade. The results of gravity model are also applied to calculate the trade potential between Vietnam and twenty three European countries. It shows that Vietnam’s trade with twenty three European countries has considerable room for growth.

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Recent developments in the field of ultracold gases has led to the production of degenerate samples of polar molecules. These have large static electric-dipole moments, which in turn causes the molecules to interact strongly. We investigate the interaction of polar particles in waveguide geometries subject to an applied polarizing field. For circular waveguides, tilting the direction of the polarizing field creates a periodic inhomogeneity of the interparticle interaction. We explore the consequences of geometry and interaction for stability of the ground state within the Thomas-Fermi model. Certain combinations of tilt angles and interaction strengths are found to preclude the existence of a stable Thomas-Fermi ground state. The system is shown to exhibit different behavior for quasi-one-dimensional and three-dimensional trapping geometries.

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To gain the full educational benefits of the major new investments in corporate technologies supporting online teaching and learning it is argued that a strategic, systems based approach to academic professional development (APD) is required. Such an approach requires a clear view of the key areas of potential and enduring teaching and learning benefit which can be realised from online developments, including an understanding of the changing role of the academic teacher in higher education, the identification of the desired professional capacities to educate online, and the implementation of a number of coordinated initiatives to develop these professional capacities in order to engage constructively with the learning and technology opportunities. Based on previous work, we propose a 6three model of Academic Professional Capacities Development for effective APD of online teaching and learning. The model can help inform the actions of policy makers, executives and practitioners in ways that promote an authentic learning organisation.

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Important eCommerce requirements are a robust and secure technical infrastructure, and the ability to ensuring the security of information, and to satisfying certain related legal requirements. In this paper, based on a literature review, we present a high-level conceptual model of information security in eCommerce, consisting of three strategic dimensions: protecting organizations' information, satisfying certain legal requirements, and enabling trusted and secure electronic transactions. Our conceptual model can be used by eCommerce managers as a tool in the strategic planning and management process, to better understand and communicate the inter-dependencies between business and legal requirements. The model can also be used for devising the goals and objectives relevant to their specific organization, for designing the policies that are needed, and deciding how technology will be managed and what training is required.

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This paper will discuss the contributing factors of; increasing numbers of international students, and the advancement of learning technologies; that lead to the development of an exploratory research study into the creation of a three phase online lecture model. Aspects such as the differences between the major cultural groups currently enrolled in Australian Universities, indicates the variations that can be expected in student learning styles. This research study aims at determining the educational value of the inclusion of online lectures for a diverse and distributed cross-cultural audience.

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This study investigated the multiple, complex, dynamic and interactive variables influencing successful reintegration of ex-prisoners, with a particular focus on the role of emotional state in the reintegration process. This involved conduct of a survey to a large group of prisoners approaching release and subsequently following release from prisons in Victoria and Queensland. Participants were 101 adult prisoners who completed a pre-release questionnaire one month prior to their release that focused on prison-related variables, participant background, and anticipated conditions upon release. A post-release questionnaire was administered to the same participants at one to four weeks and three to four months post-release, focusing on the quality of life conditions experienced following release. As well, the Beck Depression Inventory, Beck Anxiety Inventory, and the State-Trait Anger Expression Inventory were completed at each interview. Of interest, was the level and degree of change in prisoner ratings of depression, anxiety, and anger at pre-release and extending over the post-release period. As well, the strength of relationship between emotional state and the main variables influencing reintegration was investigated; that is, the degree to which reintegration variables (such as social support, drug use, post-release program participation, rated health) are associated with depression, anxiety, and anger among ex-prisoners. The report commences with the description of an ecological model of community reintegration that enables the main variables that may influence reintegration of ex-prisoners to be easily conceptualised and understood. A review of the international and Australian literature relevant to community reintegration of ex-prisoners is then presented, consistent with this conceptual framework, with a specific emphasis on the role of emotional state in post-release outcomes for this group. In the second section, the study design and method are described, with the results presented in the third section. The fourth and final section of the report includes a discussion of the results, implications for reintegration theory, and practical implications for promoting successful reintegration of ex-prisoners.

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This thesis investigates the relationship between analysis and insight in Prasarigika Madhyamika Buddhism. More specifically it asks whether analysis is a necessary and/or a sufficient condition for the generation of insight. The thesis is divided into six chapters which include an introduction, an appendix which outlines Prasangika and Svatantrika views regarding the syllogism (svatantra) and a conclusion. The remaining chapters seek to demonstrate that analysis for the Prasarigika and the Tibetan Geluk-ba school is a necessary, but not a sufficient condition for the arising of insight. Chapter one is an investigation of certain Western psychological theories which deal with the effects on the mind of cogitating upon contradictions. Though the psychological theories are only suggestive, this chapter will lend support to the claim a) of the Prasaiigika, that analysis generates an altered state of consciousness; and b) that analysis may be a necessary and sufficient condition for the generation of insight. Chapter two seeks to construct a logico-psychological model of how insight is generated. In this model it is argued that insight is a conceptual and intuitive experience: i.e. non-inferential, and that all thought comes via the intuition. This model argues that analysis is a necessary, but not a sufficient condition for the generation of insight. In chapter three an investigation of the writings of Dzong-ka-ba (Tsong-Kha-pa) is undertaken in order to ascertain how the Tibetan Geluk-ba (dGe lugs pa) school regard the relationship between analysis and insight. The model of chapter two will be compared with the Tibetan Geluk-ba accounts to gauge its explanatory power and correspondence with the Geluk-ba views. Chapter four is an investigation of the writings of certain Western scholars. This investigation seeks to ascertain how these scholars may have regarded the relationship between analysis and insight. The chapter then compares these views with the model developed in chapter two.

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Active Peer-to-Peer worms are great threat to the network security since they can propagate in automated ways and flood the Internet within a very short duration. Modeling a propagation process can help us to devise effective strategies against a worm's spread. This paper presents a study on modeling a worm's propagation probability in a P2P overlay network and proposes an optimized patch strategy for defenders. Firstly, we present a probability matrix model to construct the propagation of P2P worms. Our model involves three indispensible aspects for propagation: infected state, vulnerability distribution and patch strategy. Based on a fully connected graph, our comprehensive model is highly suited for real world cases like Code Red II. Finally, by inspecting the propagation procedure, we propose four basic tactics for defense of P2P botnets. The rationale is exposed by our simulated experiments and the results show these tactics are of effective and have considerable worth in being applied in real-world networks.

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Constructability is an important approach that allows the building industry to achieve quality outputs making best use of resources – the linked goals of time, cost and quality. Information supply and knowledge transfer are central to this and are recognized as integral to an industry strategy to improve productivity. However, poor delivery of information to those at the construction site and lack of effective methods of transferring knowledge between parties involved in construction become major challenges. This paper reviews the building production practices and information networks adopted by three countries to achieve better constructability practices. The elements of ‘control’, ‘innovation’, ‘best practice’ and ‘audit’, identified as key to improving knowledge transfer, are modelled for the construction sectors of Singapore, Australia and Malaysia. A framework for knowledge transfer is proposed to promote better practices in the construction industry.