Simulation of the load-unload response ratio and critical sensitivity in the lattice solid model

The Load-Unload Response Ratio (LURR) method is an intermediate-term earthquake prediction approach that has shown considerable promise. It involves calculating the ratio of a specified energy release measure during loading and unloading where loading and unloading periods are determined from the earth tide induced perturbations in the Coulomb Failure Stress on optimally oriented faults. In the lead-up to large earthquakes, high LURR values are frequently observed a few months or years prior to the event. These signals may have a similar origin to the observed accelerating seismic moment release (AMR) prior to many large earthquakes or may be due to critical sensitivity of the crust when a large earthquake is imminent. As a first step towards studying the underlying physical mechanism for the LURR observations, numerical studies are conducted using the particle based lattice solid model (LSM) to determine whether LURR observations can be reproduced. The model is initialized as a heterogeneous 2-D block made up of random-sized particles bonded by elastic-brittle links. The system is subjected to uniaxial compression from rigid driving plates on the upper and lower edges of the model. Experiments are conducted using both strain and stress control to load the plates. A sinusoidal stress perturbation is added to the gradual compressional loading to simulate loading and unloading cycles and LURR is calculated. The results reproduce signals similar to those observed in earthquake prediction practice with a high LURR value followed by a sudden drop prior to macroscopic failure of the sample. The results suggest that LURR provides a good predictor for catastrophic failure in elastic-brittle systems and motivate further research to study the underlying physical mechanisms and statistical properties of high LURR values. The results provide encouragement for earthquake prediction research and the use of advanced simulation models to probe the physics of earthquakes.

Load-unload response ratio and accelerating moment/energy release critical region scaling and earthquake prediction

The main idea of the Load-Unload Response Ratio (LURR) is that when a system is stable, its response to loading corresponds to its response to unloading, whereas when the system is approaching an unstable state, the response to loading and unloading becomes quite different. High LURR values and observations of Accelerating Moment/Energy Release (AMR/AER) prior to large earthquakes have led different research groups to suggest intermediate-term earthquake prediction is possible and imply that the LURR and AMR/AER observations may have a similar physical origin. To study this possibility, we conducted a retrospective examination of several Australian and Chinese earthquakes with magnitudes ranging from 5.0 to 7.9, including Australia's deadly Newcastle earthquake and the devastating Tangshan earthquake. Both LURR values and best-fit power-law time-to-failure functions were computed using data within a range of distances from the epicenter. Like the best-fit power-law fits in AMR/AER, the LURR value was optimal using data within a certain epicentral distance implying a critical region for LURR. Furthermore, LURR critical region size scales with mainshock magnitude and is similar to the AMR/AER critical region size. These results suggest a common physical origin for both the AMR/AER and LURR observations. Further research may provide clues that yield an understanding of this mechanism and help lead to a solid foundation for intermediate-term earthquake prediction.

On-line writing: a link to learning in a teacher education program

This paper examines the use of on-line discussion as a medium for learning in a pre-service teacher education program. As part of an Education Studies course student teachers engaged in a discussion of issues related to technology and equity in schools. The design of the task and the subsequent analysis of the on-line text were part of a research project investigating whether and how communications technology can be used to integrate and extend the learning of teacher education students. The main argument developed in the paper is that through the on-line activity distinctive sets of writing practices were created. These practices enabled students to make connections between the often disparate parts of teacher education programs-theory and practice, campus and school, research and experience. (C) 2002 Elsevier Science Ltd. All rights reserved.

Aligning school reform and teacher education reform in the middle years: An Australian case study

This paper discusses the development of a new Bachelor of Education (Middle Years of Schooling) at The University of Queensland. The middle years of schooling have increasingly been the focus of education reform initiatives in Australia, but this has not been accompanied by significant increases in the number of teacher education institutions offering specialised middle schooling-level teacher preparation programmes. Considering the rapidly changing social and economic context and the emergent state of middle schooling in Australia, the programme represented a conceptual and practical opportunity and challenge for The University of Queensland team. Working collaboratively, the team sought to design a teacher education preservice programme that was both responsive and generative: that is, responsive to local school contexts and to current educational research and reform at national and international levels; and generative of cutting-edge theories and practices associated with middle schooling, teachers' work, and teacher education. This paper focuses on one component of the Middle Years of Schooling Teacher Education programme at The University of Queensland; namely, the practicum. We first present the underlying principles of the practicum programme and then examine "dilemmas" that emerged early in the practicum. These issues and tensions were associated with the ideals of "middle years" philosophy and the pragmatics of school reform associated with that new approach. In this paper, and within this context, we explore what it means to be both responsive and generative, and describe how we as teacher educators negotiated between the extremes these terms implied.

Experimental study of phase equilibria in the PbO-ZnO-"Fe2O3"-(CaO+SiO2) system in air for the lead and zinc blast furnace sinters (CaO/SiO2 weight ratio of 0.933 and PbO/(CaO+SiO2) ratios of 2.0 and 3.2)

Experimental studies on phase equilibria and liquidus in the multicomponent system PbO-ZnO-CaO-SiO2-FeO-Fe2O3 in air have been conducted over the temperature range between 1323 K (1050 degreesC) and 1623 K (1350 degreesC) to characterize the phase relations of the complex slag systems encountered in lead and zinc blast furnace sinters. The liquidus in two pseudoternary sections ZnO-Fe2O3-(PbO + CaO + SiO2) with the CaO/SiO2 weight ratio of 0.933 and PbO/(CaO + SiO2) weight ratios of 2.0 and 3.2 have been constructed.

Influence of the N/K ratio on the production and quality of cucumber in hydroponic system

The objective of this work was to evaluate the quality of fruits and the nutritional status of cucumber CV. Aodai cultivated in nutrient solutions with different N:K ratios. The hydroponic cultivation was initially performed, during the vegetative growth, in nutrient solution with 1:2.0 mmol L-1 N:K, and, later, during fruit setting, in four different nutrient solutions with N:K (w/w) at the ratios 1:1.4, 1:1.7, 1:2.0 and 1:2.5. An additional treatment with a nutrient solution containing the ratio 1:2.2 (w/w) N:K during the vegetative growth and N:K 1:1.4 (w/w) during fruit setting, both with 10% ammonium (NH4+) was included. The treatments were arranged in a randomized design with six replicates. Irrigation was carried out with deionized water until seed germination, and then with nutrient solution until 30 days after germination, when plants were transplanted. Plants in the hydroponic growing beds were irrigated with the solutions for vegetative growth, and, after 21 days, the solutions were replaced by solutions for fruit setting. At 45 and 60 days after transplanting, the fresh weight, length, diameter, volume and firmness of the fruit were evaluated, and, at 45 days after transplanting, the macronutrient concentrations in the leaves were determined. The use of different N:K ratios during fruit setting influenced the cucumber production. The ratio of 1.0:1.7 N: K (w/w), with 10% of N in the form of ammonia, is recommended for the whole cycle.

Applying complex network theory to the understanding of high-aspect-ratio carbon-filled composites

This work demonstrates that the theoretical framework of complex networks typically used to study systems such as social networks or the World Wide Web can be also applied to material science, allowing deeper understanding of fundamental physical relationships. In particular, through the application of the network theory to carbon nanotubes or vapour-grown carbon nanofiber composites, by mapping fillers to vertices and edges to the gap between fillers, the percolation threshold has been predicted and a formula that relates the composite conductance to the network disorder has been obtained. The theoretical arguments are validated by experimental results from the literature.

The influence of matrix mediated hopping conductivity, filler concentration, aspect ratio and orientation on the electrical response of carbon nanotube/polymer nanocomposites

A model to simulate the conductivity of carbon nanotube/polymer nanocomposites is presented. The proposed model is based on hopping between the fillers. A parameter related to the influence of the matrix in the overall composite conductivity is defined. It is demonstrated that increasing the aspect ratio of the fillers will increase the conductivity. Finally, it is demonstrated that the alignment of the filler rods parallel to the measurement direction results in higher conductivity values, in agreement with results from recent experimental work.

Comparison of pupil diameter and tear production in dogs treated with acepromazine, tramadol and their combination

Some ophthalmic surgeries require induction of mydriasis, however, drugs traditionally used for this purpose significantly reduces tear production. To evaluate the effect of acepromazine and tramadol, used alone or in combination, on pupil diameter, tear production, heart and respiratory rate, systolic blood pressure and rectal temperature, these drugs were administered to seven clinically normal dogs divided into three experimental groups (G1 - acepromazine; G2 - tramadol; G3 - tramadol + acepromazine) that differed only in the sedation protocol. Parameters were measured in four experimental moments. Miosis occurred in G1, in addition to reduced tear production and respiratory rate. No significant changes were found in the parameters assessed in G2, whereas in G3, there was decrease in tear production of the right eye, decrease in the respiratory rate and rectal temperature. Tramadol proved to be a drug suitable for pre-anesthetic procedures that require the maintenance of pupil diameter and keeps the tear production within normal parameters. However, the use of acepromazine alone or in combination with tramadol requires protection of the patient's eye surface to prevent the occurrence of undesirable ophthalmic changes.

Analysis of the return on preventive measures in musculoskeletal disorders through the benefitecost ratio: A case study in a hospital

Work-related musculoskeletal disorders (WMSDs) are among the most costly health problems that society is facing today. Prevention involves investments and it is important for organizations to make a cost ebenefit analysis of ergonomic projects. Return on prevention is a recent concern in the domain of occupational safety and health (OSH). There are many studies concerning the return on the prevention of WMSDs, in terms of the benefits for the organization in which the preventive measures are implemented. However, it is also important to perform an analysis of the impact of each measure on society (externalities). A model to perform a financial and economic costebenefit analysis related to OSH projects was developed and it was applied in the case of the prevention of WMSDs in a Portuguese hospital. An analysis of the accidents and corresponding costs has been made in six of the services of the hospital. Financial and an economic costebenefit analysis have been made and the benefitecost ratio (B/C) has been calculated. While the B/C financial ratio, considering only the benefits to the hospital, is around 2, the economic B/C ratio, taking into account all the external benefits that have been quantified, is higher than 14. Relevance to industry: Both the economic and the financial B/C ratio are important support tools for decision makers in public and private organizations, helping them to define which preventive measures should be implemented, taking into account the costs involved and the resulting quantified benefits, for the organization, for the workers and for the society.

"Odds ratio": algumas considerações

Tem sido grande o número de estudos retrospectivos e transversais controlados que utilizam o "odds ratio" como medida de intensidade de associação. Visando melhor compreensão do significado desta medida, o "odds ratio" foi comparado com a razão de prevalências; foi estudado o comportamento desta medida em relação a variação amostrai de prevalência do fator de risco nos casos e nos controles; e a importância de expressar o "odds ratio" com o respectivo intervalo de confiança.

O currículo e as necessidades educativas especiais : práticas de adequação curricular no terceiro ciclo

A responsabilidade da construção de uma escola para todos deve ser o grande objectivo de todo e qualquer professor, criando espaços de reflexão conjunta no sentido de serem traçados projectos curriculares diferenciados que dêem resposta a todos os alunos na sua diversidade plural. Assim, a concepção e construção da escola inclusiva implicam mudanças, quer nas atitudes e práticas dos agentes educativos, quer nas estruturas do sistema de ensino ao nível organizacional e da gestão curricular. Neste âmbito, a adequação do currículo às necessidades educativas especiais (NEE) dos alunos torna-se essencial na (re)construção e operacionalização dos diferentes processos curriculares. O trabalho que agora se apresenta foi desenvolvido através de um estudo de caso. Constitui uma tentativa de compreensão das percepções dos professores e das práticas pedagógicas que desenvolvem para efectuar adequações curriculares para alunos com NEE. Centrámo-nos nos professores de um conselho de turma do sétimo ano do terceiro ciclo do ensino básico (3º CEB) que inclui uma aluna com NEE, procurando saber o que pensam sobre o processo de adequação curricular, como o concebem e como o implementam. Como metodologia de recolha dos dados utilizamos as técnicas da entrevista, da análise documental e da observação naturalista. Concluímos que, apesar das dificuldades que expressam e demonstram, os professores assumem a necessidade de implementar adequações curriculares face às NEE dos alunos, como resposta às diferenças e particularidades de cada um, tendo em vista o desenvolvimento de competências essenciais e a conclusão da escolaridade obrigatória. As Adequações Curriculares são percepcionadas como muito vantajosas do ponto de vista da promoção do sucesso educativo para todos os alunos e em particular para os alunos com NEE, proporcionando a estes, acompanhar o currículo mais próximo do que é normal, sentirem-se como “iguais” aos seus colegas, melhorar a sua auto-estima, auto-confiança e motivação ABSTRACT The responsibility of building a school for all must be the ultimate goal of any teacher, creating spaces for joint reflection in order to draw differentiated curricular projects which respond to all students in their plural diversity. Thus, the design and construction of the inclusive school involve changes both in attitudes and practices of the educational agents, and in the structures of the education system regarding the organization and the curriculum management. In this context, the adequacy of the curriculum to students’ special educational needs (SEN) becomes essential in the (re) construction and operationalization of the different curriculum processes. The work now presented was developed through a case study. It attempts to understand the perceptions of teachers and the pedagogical practices they develop to make curricular adjustments for students with SEN. We focused on the teachers of a seventh year class of the third cycle of basic education (3rd CBE) which includes a pupil, a girl, with SEN, trying to find out what they think about the process of adapting the curriculum, how they conceive and implement it. As a methodology of data collection we used different techniques: the interview, the documentary analysis and the naturalistic observation. We concluded that, despite the difficulties that teachers express and demonstrate they assume the need to implement curricular adjustments in relation to pupils with SEN in response to the differences and particularities of each one in order to develop core competencies and to complete compulsory schooling. The Curriculum Adequacies are perceived as very advantageous from the standpoint of promoting educational success for all students and particularly for pupils with SEN, providing the latter the possibility of following the curriculum closer than usual, feeling as "equal" to their schoolmates, improving their self-esteem, self- confidence and motivation.

Becoming a teacher: student teachers´ experiences and perceptions about teaching practice

In an attempt to build a more comprehensive and holistic understanding of the complexity, dynamics and idiosyncrasies involved in becoming a teacher, this study focussed on the experiences of 295 student teachers. Their feelings, cognitions and perceptions regarding teaching practice were analysed using the short version of the Inventory of Experiences and Perceptions of the Teaching Practice. Results emphasise some of the difficulties experienced during this period (e.g., stress, sense of weariness and ‘vulnerability’), as well the positive perceptions of these student teachers regarding their growing knowledge and skilfulness, as well as their sense of efficacy, flexibility and spontaneity in their performance and interactions. Their perception of their accomplishments in achieving reasonable levels of acceptance and recognition within the school community and their positive evaluation of the guidance and support provided by their supervisors are also emphasised. Differences were found – in terms of gender and graduate course background – in the way these student teachers experienced some aspects of teaching practice.

OC/EC ratio observations in Europe: Re-thinking the approach for apportionment between primary and secondary organic carbon

This study explores a large set of OC and EC measurements in PM(10) and PM(2.5) aerosol samples, undertaken with a long term constant analytical methodology, to evaluate the capability of the OC/EC minimum ratio to represent the ratio between the OC and EC aerosol components resulting from fossil fuel combustion (OC(ff)/EC(ff)). The data set covers a wide geographical area in Europe, but with a particular focus upon Portugal, Spain and the United Kingdom, and includes a great variety of sites: urban (background, kerbside and tunnel), industrial, rural and remote. The highest minimum ratios were found in samples from remote and rural sites. Urban background sites have shown spatially and temporally consistent minimum ratios, of around 1.0 for PM(10) and 0.7 for PM(2.5).The consistency of results has suggested that the method could be used as a tool to derive the ratio between OC and EC from fossil fuel combustion and consequently to differentiate OC from primary and secondary sources. To explore this capability, OC and EC measurements were performed in a busy roadway tunnel in central Lisbon. The OC/EC ratio, which reflected the composition of vehicle combustion emissions, was in the range of 03-0.4. Ratios of OC/EC in roadside increment air (roadside minus urban background) in Birmingham, UK also lie within the range 03-0.4. Additional measurements were performed under heavy traffic conditions at two double kerbside sites located in the centre of Lisbon and Madrid. The OC/EC minimum ratios observed at both sites were found to be between those of the tunnel and those of urban background air, suggesting that minimum values commonly obtained for this parameter in open urban atmospheres over-predict the direct emissions of OC(ff) from road transport. Possible reasons for this discrepancy are explored. (C) 2011 Elsevier Ltd. All rights reserved.