139 resultados para Two Dimensions
em University of Queensland eSpace - Australia
Resumo:
A balanced sampling plan excluding contiguous units (or BSEC for short) was first introduced by Hedayat, Rao and Stufken in 1988. These designs can be used for survey sampling when the units are arranged in one-dimensional ordering and the contiguous units in this ordering provide similar information. In this paper, we generalize the concept of a BSEC to the two-dimensional situation and give constructions of two-dimensional BSECs with block size 3. The existence problem is completely solved in the case where lambda = 1.
Resumo:
We examined the unique relations between the five dimensions of the Attachment Style Questionnaire (ASQ; Feeney, Noller, & Hanrahan, 1994) and depression and agoraphobic behavior (i.e., avoidance of situations where high anxiety is experienced). In addition, we examined mediation models in an attempt to clarify the link between adult attachment and these two dimensions of psychopathology. In testing these models, we administered the ASQ, General Self-Efficacy Scale, Agoraphobic Catastrophic Cognitions Questionnaire, Beck Depression Inventory, and the Mobility Inventory for Agoraphobia (a measure of the degree to which situations are avoided that are typically anxiety provoking for people with agoraphobia) to 122 participants (44 with agoraphobia, 25 with a current major depressive disorder, and 53 with no current psychopathology). The results showed that the insecure attachment dimensions of need for approval, preoccupation with relationships, and relationships as secondary were uniquely associated with depression and that general self-efficacy partly mediated the relationship between need for approval and depression. In contrast, only preoccupation with relationships was uniquely associated with agoraphobic behavior, and catastrophic cognitions about bodily sensations partly mediated this association.
Resumo:
Impulsivity is now widely viewed as a multidimensional construct consisting of a number of related dimensions. Although many measures of impulsivity are correlated, most recent factor analyses support at least a two-factor model. In the current paper, these two factors have been labelled reward sensitivity, reflecting one of the primary dimensions of Gray's personality theory, and rash-spontaneous impulsiveness. The evidence supporting the existence of two dimensions of impulsivity is reviewed in relation to substance misuse and binge eating. (C) 2004 Elsevier Ltd. All rights reserved.
Resumo:
In a previous study (Jones and Smith, 1999) we established that much the same core pattern of national identity characterizes many developed countries. Using the national identity module from the 1995 International Social Survey Programme, we identified two dimensions of national identity: an ascriptive dimension resembling the concept of ethnic identity described in the historical and theoretical literature, and a voluntarist dimension closer to the notion of civic identity. Some writers view these dimensions in terms of a historical sequence but we find that both constructs coexist in the minds of individual respondents in the nations we examine (we exclude Bulgaria and the Philippines from the present but not the earlier analysis). The dataset used for the multilevel analyses reported here consists of 28 589 respondents in the remaining 21 countries included in the national identity database for the 1995 round of surveys. The macrosociological literature on national identity does not offer well-defined predictions about what precise patterns of national identification we might expect to find among the masses of the developed countries. There are, however, recurring themes from which one can construct plausible hypotheses about how countries might differ according to their level of development, broadly conceived. Thus, we hypothesize that forces such as post-industrialism and globalization tend to favour the more open voluntaristic form of national identity over the more restrictive ascribed form. We develop different multi-level models in order to evaluate specific hypotheses pertaining to such issues, by simultaneously relating individual and societal characteristics to the relative strength of individual commitment to these different types of national identity.
Resumo:
The particle-based Lattice Solid Model (LSM) was developed to provide a basis to study the physics of rocks and the nonlinear dynamics of earthquakes (MORA and PLACE, 1994; PLACE and MORA, 1999). A new modular and flexible LSM approach has been developed that allows different microphysics to be easily included in or removed from the model. The approach provides a virtual laboratory where numerical experiments can easily be set up and all measurable quantities visualised. The proposed approach provides a means to simulate complex phenomena such as fracturing or localisation processes, and enables the effect of different micro-physics on macroscopic behaviour to be studied. The initial 2-D model is extended to allow three-dimensional simulations to be performed and particles of different sizes to be specified. Numerical bi-axial compression experiments under different confining pressure are used to calibrate the model. By tuning the different microscopic parameters (such as coefficient of friction, microscopic strength and distribution of grain sizes), the macroscopic strength of the material and can be adjusted to be in agreement with laboratory experiments, and the orientation of fractures is consistent with the theoretical value predicted based on Mohr-Coulomb diagram. Simulations indicate that 3-D numerical models have different macroscopic properties than in 2-D and, hence, the model must be recalibrated for 3-D simulations. These numerical experiments illustrate that the new approach is capable of simulating typical rock fracture behaviour. The new model provides a basis to investigate nucleation, rupture and slip pulse propagation in complex fault zones without the previous model limitations of a regular low-level surface geometry and being restricted to two-dimensions.
Resumo:
Regional commodity forecasts are being used increasingly in agricultural industries to enhance their risk management and decision-making processes. These commodity forecasts are probabilistic in nature and are often integrated with a seasonal climate forecast system. The climate forecast system is based on a subset of analogue years drawn from the full climatological distribution. In this study we sought to measure forecast quality for such an integrated system. We investigated the quality of a commodity (i.e. wheat and sugar) forecast based on a subset of analogue years in relation to a standard reference forecast based on the full climatological set. We derived three key dimensions of forecast quality for such probabilistic forecasts: reliability, distribution shift, and change in dispersion. A measure of reliability was required to ensure no bias in the forecast distribution. This was assessed via the slope of the reliability plot, which was derived from examination of probability levels of forecasts and associated frequencies of realizations. The other two dimensions related to changes in features of the forecast distribution relative to the reference distribution. The relationship of 13 published accuracy/skill measures to these dimensions of forecast quality was assessed using principal component analysis in case studies of commodity forecasting using seasonal climate forecasting for the wheat and sugar industries in Australia. There were two orthogonal dimensions of forecast quality: one associated with distribution shift relative to the reference distribution and the other associated with relative distribution dispersion. Although the conventional quality measures aligned with these dimensions, none measured both adequately. We conclude that a multi-dimensional approach to assessment of forecast quality is required and that simple measures of reliability, distribution shift, and change in dispersion provide a means for such assessment. The analysis presented was also relevant to measuring quality of probabilistic seasonal climate forecasting systems. The importance of retaining a focus on the probabilistic nature of the forecast and avoiding simplifying, but erroneous, distortions was discussed in relation to applying this new forecast quality assessment paradigm to seasonal climate forecasts. Copyright (K) 2003 Royal Meteorological Society.
Resumo:
At a broad level, it has been shown that different institutional contexts, policy regimes and business systems affect the kinds of activities in which a nation specialises. This paper is concerned with the way in which different national business systems affect the nature of participation of a nation in the knowledge economy. The paper seeks to explain cross-national variations in the knowledge economy in the Australia, Denmark and Sweden with reference to dominant characteristics of the business system. Although Australia, Denmark and Sweden are all small wealthy countries, they each have quite distinctive business systems. Australia has been regarded as a variant of the competitive business system and has generally been described as an entrepreneurial economy with a large small firm population. In contrast Sweden has a coordinated business system that has favoured large industrial firms. The Danish variant of the coordinated model, with its well-developed vocational training system, is distinguishable by its large population of networked small and medium size enterprises. The three countries also differ significantly on two dimensions of participation in the knowledge economy. First, there is cross-national variation in patterns of specialisation in knowledge intensive industries and services. Second, the institutional infrastructure of the knowledge economy (or the existing stock of knowledge and competence in the economy, the potential for generation and diffusion a new knowledge and the capacity for commercialisation of new ideas) differs across the three countries. This paper seeks to explain variations in these two dimensions of the knowledge economy with reference to characteristics of the business system in the three countries.
Resumo:
This paper examines the complexity of collaboration between child protection and mental health services, where a parent has a mental illness and there are protection concerns for children. The paper reports on data from focused in-depth interviews with 36 child protection workers, adult mental health workers and child and youth mental health workers. Data were analysed thematically, using NVivo to facilitate data management and analysis. Two dimensions were identified. The first, the process of collaboration, relates to four factors that assisted the collaborative process: communication, knowledge, role clarity and resources. The second dimension considers the challenges presented to collaborative work when a parent has a mental illness and a child is in need of protection, and identifies issues that are inherent in cases of this kind. Two types of challenge were identified. The first related to characteristics of mental illness, and included the episodic and/or unpredictable nature of mental illness, incorporating information from psychiatric and parenting capacity assessments, and the provision of ongoing support. The second type of challenge concerned the tension between the conflicting needs of parents and their children, and how this was viewed from both the adult mental health and the child protection perspective. Implications for policy and practice are identified in relation to the need for service models that provide ongoing, flexible support that can be intensified or held back as needed.
Resumo:
An appreciation of the physical mechanisms which cause observed seismicity complexity is fundamental to the understanding of the temporal behaviour of faults and single slip events. Numerical simulation of fault slip can provide insights into fault processes by allowing exploration of parameter spaces which influence microscopic and macroscopic physics of processes which may lead towards an answer to those questions. Particle-based models such as the Lattice Solid Model have been used previously for the simulation of stick-slip dynamics of faults, although mainly in two dimensions. Recent increases in the power of computers and the ability to use the power of parallel computer systems have made it possible to extend particle-based fault simulations to three dimensions. In this paper a particle-based numerical model of a rough planar fault embedded between two elastic blocks in three dimensions is presented. A very simple friction law without any rate dependency and no spatial heterogeneity in the intrinsic coefficient of friction is used in the model. To simulate earthquake dynamics the model is sheared in a direction parallel to the fault plane with a constant velocity at the driving edges. Spontaneous slip occurs on the fault when the shear stress is large enough to overcome the frictional forces on the fault. Slip events with a wide range of event sizes are observed. Investigation of the temporal evolution and spatial distribution of slip during each event shows a high degree of variability between the events. In some of the larger events highly complex slip patterns are observed.
Resumo:
The mechanism of bainite growth has been investigated using in situ transmission electron microscopy observations. It was found that, in a number of alloys studied, a bainitic embryo is made of basic transformation units. These units are either a group of stacking faults or, in two dimensions, a series of parallelograms of different sizes. Thickening/widening of the bainite embryo takes place through shear along the stacking fault planes or twining planes. The bainite embryo is elongated by the formation of new transformation units at both tips of the bainite plate. The three-dimensional morphology of bainite is a convex tens-like lath. It is believed that the bainite embryo grows by shearing, which is controlled by the diffusion of solute atoms during the transformation. As the growth rate is much lower than that of martensite, it is therefore detectable. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Resumo:
This Study invesdgated the impact of teacher behaviours on student quaUt}' of school Ufe (SQSL). A measure of teacher organisadonal cidzenship behaviour (OCB) was developed, tapping two dimensions of organisadon-focused OCB (OCBO) and one dimension of individual-focused OCB (OCBI). In Une with previous research suggesdng that OCBOs may consdtute efficacyenhancing experiences, as weU as studies demonstradng the posidve consequences of teacher efficacy for students, we expected teacher efficacy to mediate the reladonship between OCBO and SQSL. Hypotheses were tested in a muldlevel design in which 171 teachers and their students (N=3018) completed quesdonnaires. A significant propordon of variance in SQSL was attributable to classroom factors. Support was found for the main effects of OCBO, as well as the main and mediadng effects of teacher efficacy.
Resumo:
As part of a major ongoing project, we consider and compare contemporary patterns of address pronoun use in four major European languages- French, German, Italian and Swedish. We are specifically interested in two major aspects: intralingual behaviour, that is, within the same language community, and interlingual dimensions of address pronoun use. With respect to the former, we summarize our key findings to date. We then give consideration in a more preliminary fashion to issues and evidence relevant to the latter.
Resumo:
Two major factors are likely to impact the utilisation of remotely sensed data in the near future: (1)an increase in the number and availability of commercial and non-commercial image data sets with a range of spatial, spectral and temporal dimensions, and (2) increased access to image display and analysis software through GIS. A framework was developed to provide an objective approach to selecting remotely sensed data sets for specific environmental monitoring problems. Preliminary applications of the framework have provided successful approaches for monitoring disturbed and restored wetlands in southern California.
Resumo:
One of the primary personality dimensions or traits that has consistently been linked to substance abuse is impulsivity. However, impulsivity is not a homogenous construct and although many of the measures of impulsivity are correlated, the most recent review of published factor analytic studies has proposed two independent dimensions of impulsivity: reward sensitivity, reflecting one of the primary dimension of J. A. Gray's personality theory, and rash impulsiveness. These two facets of impulsivity derived from the field of personality research parallel recent developments in the neurosciences where changes in the incentive value of rewarding substances has been linked to alterations in neural substrates involved in reward seeking and with a diminished capacity to inhibit behavior due to chronic drug exposure. In this paper, we propose a model that integrates the findings from research into individual differences with recent models of neural substrates implicated in the development of substance misuse. (C) 2004 Elsevier Ltd. All rights reserved.
Resumo:
A new conceptual model for soil pore-solid structure is formalized. Soil pore-solid structure is proposed to comprise spatially abutting elements each with a value which is its membership to the fuzzy set ''pore,'' termed porosity. These values have a range between zero (all solid) and unity (all pore). Images are used to represent structures in which the elements are pixels and the value of each is a porosity. Two-dimensional random fields are generated by allocating each pixel a porosity by independently sampling a statistical distribution. These random fields are reorganized into other pore-solid structural types by selecting parent points which have a specified local region of influence. Pixels of larger or smaller porosity are aggregated about the parent points and within the region of interest by controlled swapping of pixels in the image. This creates local regions of homogeneity within the random field. This is similar to the process known as simulated annealing. The resulting structures are characterized using one-and two-dimensional variograms and functions describing their connectivity. A variety of examples of structures created by the model is presented and compared. Extension to three dimensions presents no theoretical difficulties and is currently under development.