Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals

The dynamical properties of an extended Hubbard model, which is relevant to quarter-filled layered organic molecular crystals, are analyzed. We have computed the dynamical charge correlation function, spectral density, and optical conductivity using Lanczos diagonalization and large-N techniques. As the ratio of the nearest-neighbor Coulomb repulsion, V, to the hopping integral, t, increases there is a transition from a metallic phase to a charge-ordered phase. Dynamical properties close to the ordering transition are found to differ from the ones expected in a conventional metal. Large-N calculations display an enhancement of spectral weight at low frequencies as the system is driven closer to the charge-ordering transition in agreement with Lanczos calculations. As V is increased the charge correlation function displays a collective mode which, for wave vectors close to (pi,pi), increases in amplitude and softens as the charge-ordering transition is approached. We propose that inelastic x-ray scattering be used to detect this mode. Large-N calculations predict superconductivity with d(xy) symmetry close to the ordering transition. We find that this is consistent with Lanczos diagonalization calculations, on lattices of 20 sites, which find that the binding energy of two holes becomes negative close to the charge-ordering transition.

Reducing the height of a circular array of monopoles using top hats and dielectric coatings

Using a Radial Guide Field Matching Method, an investigation is performed into reducing the height of an electronically steered circular array of monopole antennas composed of a central active element surrounded by passive elements being either short- or open-circuited. It is shown that a considerable height reduction can be achieved using top hats attached to monopoles ends and by applying dielectric coating underneath the top hats. The trade-off in achieving height reduction is narrower impedance bandwidth.

Full S matrix calculation via a single real-symmetric Lanczos recursion: The Lanczos artificial boundary inhomogeneity method

We present an efficient and robust method for the calculation of all S matrix elements (elastic, inelastic, and reactive) over an arbitrary energy range from a single real-symmetric Lanczos recursion. Our new method transforms the fundamental equations associated with Light's artificial boundary inhomogeneity approach [J. Chem. Phys. 102, 3262 (1995)] from the primary representation (original grid or basis representation of the Hamiltonian or its function) into a single tridiagonal Lanczos representation, thereby affording an iterative version of the original algorithm with greatly superior scaling properties. The method has important advantages over existing iterative quantum dynamical scattering methods: (a) the numerically intensive matrix propagation proceeds with real symmetric algebra, which is inherently more stable than its complex symmetric counterpart; (b) no complex absorbing potential or real damping operator is required, saving much of the exterior grid space which is commonly needed to support these operators and also removing the associated parameter dependence. Test calculations are presented for the collinear H+H-2 reaction, revealing excellent performance characteristics. (C) 2004 American Institute of Physics.

On the possibility of elastic strain localisation in a fault

The phenomenon of strain localisation is often observed in shear deformation of particulate materials, e.g., fault gouge. This phenomenon is usually attributed to special types of plastic behaviour of the material (e.g., strain softening or mismatch between dilatancy and pressure sensitivity or both). Observations of strain localisation in situ or in experiments are usually based on displacement measurements and subsequent computation of the displacement gradient. While in conventional continua the symmetric part of the displacement gradient is equal to the strain, it is no longer the case in the more realistic descriptions within the framework of generalised continua. In such models the rotations of the gouge particles are considered as independent degrees of freedom the values of which usually differ from the rotation of an infinitesimal volume element of the continuum, the latter being described for infinitesimal deformations by the non-symmetric part of the displacement gradient. As a model for gouge material we propose a continuum description for an assembly of spherical particles of equal radius in which the particle rotation is treated as an independent degree of freedom. Based on this model we consider simple shear deformations of the fault gouge. We show that there exist values of the model parameters for which the displacement gradient exhibits a pronounced localisation at the mid-layers of the fault, even in the absence of inelasticity. Inelastic effects are neglected in order to highlight the role of the independent rotations and the associated additional parameters. The localisation-like behaviour occurs if (a) the particle rotations on the boundary of the shear layer are constrained (this type of boundary condition does not exist in a standard continuum) and (b) the contact moment-or bending stiffness is much smaller than the product of the effective shear modulus of the granulate and the square of the width of the gouge layer. It should be noted however that the virtual work functional is positive definite over the range of physically meaningful parameters (here: contact stiffnesses, solid volume fraction and coordination number) so that strictly speaking we are not dealing with a material instability.

Empirical investigation of investment behaviour in Australia's pastoral region

Optimal intertemporal investment behaviour of Australian pastoralists is modelled using panel data for the period 1979-1993. Results indicate that quasi-fixity of inputs of labour, capital, sheep numbers and cattle numbers is characteristic of production in the pastoral region. It takes about two years for labour, four years for capital and a little over two years for both sheep numbers and cattle numbers to adjust towards long-run optimal levels. Results also indicate that, after accounting for adjustment costs, own-price product supply and input demand responses are inelastic in both the short and long run.

Anisotropic scattering and anomalous normal-state transport in a high-temperature superconductor

The metallic state of high-temperature copper-oxide superconductors, characterized by unusual and distinct temperature dependences in the transport properties(1-4), is markedly different from that of textbook metals. Despite intense theoretical efforts(5-11), our limited understanding is impaired by our inability to determine experimentally the temperature and momentum dependence of the transport scattering rate. Here, we use a powerful magnetotransport probe to show that the resistivity and the Hall coefficient in highly doped Tl2Ba2CuO6+delta originate from two distinct inelastic scattering channels. One channel is due to conventional electron electron scattering; the other is highly anisotropic, has the same symmetry as the superconducting gap and a magnitude that grows approximately linearly with temperature. The observed form and anisotropy place tight constraints on theories of the metallic state. Moreover, in heavily doped non-superconducting La2-xSrxCuO4, this anisotropic scattering term is absent(12), suggesting an intimate connection between the origin of this scattering and superconductivity itself.

Standardising bull breeding soundness evaluations and reporting in Australia

There is substantial variation in bull breeding soundness evaluation procedures and reports in Australia; the situation is compounded by difficulties in interpretation and the validity of many reports. In an effort to overcome this, the scientific literature was reviewed [Fordyce G. In: Fordyce G, editor. Bull fertility: selection and management in Australia. Eight Mile Plains, Australia: Australian Cattle Vets; 2002] and the needs of stakeholders were considered in preparing a manual, Evaluating and Reporting Bull Fertility [Entwistle KW, Fordyce G. Evaluating and reporting bull fertility. Eight Mile Plains, Australia: Australian Cattle Vets; 2003.] that outlined standards for assessing and reporting bull breeding soundness. A new recording and reporting system, called Bull Reporter, is based on standards from this manual and groups bull fertility traits into five summary categories: Scrotum, Physical, Crush-side Semen, Sperm Morphology, and Serving. The client will generally select which categories they wish to have included in the evaluation to suit their specific purposes. While there is adequate room for comments, the veterinarian is not required to make an overall judgment of whether the bull has normal capacity to sire calves under natural mating management, but ensures the standards for each selected category are met. Professional, standardised, easy-to-read reports are produced either electronically [Entwistle KW, Fordyce G. Evaluating and reporting bull fertility. Eight Mile Plains, Australia: Australian Cattle Vets; 2003.] or manually. A bull owner or their agent signs the certificate to affirm that bulls have not undergone procedures to rectify faults which may have otherwise caused them to fail the standards. An accreditation system for assessing sperm morphology was established because of its demonstrated relationship with pregnancy rates and because of the difficulties in achieving consistent and accurate assessments among laboratories. It is considered that Bull Reporter is applicable to beef and dairy bulls across all levels of management, genotypes and environments throughout Australia, with substantial potential for application elsewhere in the world. Crown Copyright (c) 2006 Published by Elsevier Inc. All rights reserved.

Online referral and OPD booking from the GP desktop

The Brisbane Inner South E-referral Project (BISEP) developed an application which allowed general practitioners, from their desktop, to successfully search for and book an available hospital outpatient appointment for patients with suspected cancer, send the referral electronically, and inform the patient of both the appointment and referral during the consultation. The hospital changed their outpatient department processes to allow such functionality for local GPs with patients with suspected cancer, working from a mutually agreed set of best practice referral criteria. A group of 19 GPs participated in an 11-week pilot implementation of the application, and were enthusiastic about continuing and expanding the approach. Patient satisfaction measures post intervention indicated that they perceived no major disadvantage in this form of outpatient department referral.

Increased health care utilization and increased antiretroviral use in HIV-infected individuals with mental health disorders

Objectives The aims of the study were to describe the prevalence and associations of mental health disorder (MHD) among a cohort of HIV-infected patients attending the Victorian HIV/AIDS Service between 1984 and 2000, and to examine whether antiretroviral therapy use or mortality was influenced by MHD (defined as a record of service provision by psychiatric services on the Victorian Psychiatric Case Register). It was hypothesized that HIV-positive individuals with MHD would have poorer treatment outcomes, reduced responses to highly active antiretroviral therapy (HAART) and increased mortality compared with those without MHD. Methods This is a retrospective cohort of 2981 individuals (73% of the Victorian population diagnosed with HIV infection) captured on an HIV database which was electronically matched with the public Victorian Psychiatric Case Register (VPCR) (accounting for 95% of public system psychiatry service provision). The prevalence, dates and recorded specifics of mental health disorders at the time of the electronic match on 1 June 2000 are described. The association with recorded MHD, gender, age, AIDS illness, HIV exposure category, duration and type of antiviral therapy, treatment era (prior to 1986, post-1987 and pre-HAART, and post-HAART) on hospitalization and mortality at 1 September 2001 was assessed. Results Five hundred and twenty-five individuals (17.6% of the Victorian HIV-positive population) were recorded with MHD, most frequently coded as attributable to substance dependence/abuse or affective disorder. MHD was diagnosed prior to HIV in 33% and, of those diagnosed after HIV, 93.8% were recorded more than 1 year after the HIV diagnosis. Schizophrenia was recorded in 6% of the population with MHD. Hospitalizations for both psychiatric and nonpsychiatric illness were more frequent in those with MHD (relative risk 5.4; 95% confidence interval 3.7, 8.2). The total number of antiretrovirals used (median 6.4 agents vs 5.5 agents) was greater in those with MHD. When adjusted for antiretroviral treatment era, HIV exposure category, CD4 cell count and antiretroviral therapy, survival was not affected by MHD. Conclusions MHD is frequent in this population with HIV infection and is associated with increased healthcare utilization but not with reduced survival.

A Z based approach to verifying security protocols

Security protocols preserve essential properties, such as confidentiality and authentication, of electronically transmitted data. However, such properties cannot be directly expressed or verified in contemporary formal methods. Via a detailed example, we describe the phases needed to formalise and verify the correctness of a security protocol in the state-oriented Z formalism.

SUPORTE SOCIAL E AUTOEFICÁCIA EM IDOSOS

As questões do desenvolvimento humano desde tempos remotos são de interesse das diversas áreas do conhecimento. Tendo em vista o aumento da expectativa de vida, as questões relacionadas ao processo de envelhecimento ganharam importância, principalmente no que tange às políticas de saúde. A saúde é preocupação central no campo do envelhecimento, uma vez que problemas de saúde podem acarretar diversas dificuldades para os idosos e para suas famílias. Este estudo teve por objetivo buscar identificar as associações entre percepções de suporte social e autoeficácia em idosos. Suporte social e autoeficácia são variáveis estudadas em contextos diversos. Estudos revelam que ambas são capazes de colaborar para proteger e promover saúde. Suporte social diz respeito ao grupo de informações que leva o indivíduo a acreditar que é valorizado, amado e estimado e que o faz sentir-se pertencente a uma rede social de comunicação recíproca. Autoeficácia pode ser definida como o conjunto de crenças que o indivíduo tem sobre suas capacidades para organizar e executar ações para o cumprimento de tarefas específicas. Portanto, identificar a existência de associações entre as percepções de suporte social e autoeficácia pode contribuir para dar maior solidez aos conhecimentos já existentes sobre esses temas e sobre o processo de envelhecimento. Participaram do estudo 61 idosos de ambos os sexos, com idade média de 67 anos, com grau de escolaridade que variou entre ensino fundamental até pós-graduação e participantes em ações de promoção à saúde. Todos foram voluntários e autorizaram sua participação por meio da assinatura de termo de consentimento. A coleta de dados foi feita mediante a aplicação de questionário contendo escalas para avaliar os construtos, além de questões para caracterização dos participantes. Os dados foram analisados eletronicamente por meio do cálculo de frequências, percentuais, médias e desvios padrão. Para se testar a hipótese, foi calculada a correlação (r de Pearson) entre as variáveis do estudo. Entre os resultados obtidos, a percepção de suporte social, tanto na dimensão emocional quanto na dimensão prática, para os idosos participantes deste estudo, é de que muitas vezes são amados, cuidados, estimados, valorizados e, que pertencem a uma rede de comunicação e obrigações mútuas. Em se tratando da percepção da autoeficácia, constatou-se que esses participantes possuem crenças de que às vezes é verdade que são eficazes e que conseguem organizar e executar ações para o cumprimento de tarefas específicas. Aponta-se ainda que não existem correlações significativas entre percepção de suporte social e autoeficácia, ou seja, os níveis de percepção de suporte social não variam proporcionalmente à variação das crenças de autoeficácia em idosos. Isto significa dizer que para estes participantes, não seria eficaz investir em melhorias do suporte social, pois isto não teria impacto em suas crenças de autoeficácia. Indica-se a realização de novas pesquisas com idosos não participantes de ações de promoção à saúde, pois se pode pensar que idosos não engajados nestes tipos de ações poderiam necessitar de maior suporte social e assim, terem suas crenças de autoeficácia associadas à sua percepção de suporte social.

IMPACTO DE FATORES PSICOSSOCIAIS SOBRE O DESEMPENHO: UM ESTUDO COM TUTORES EM EAD

Considerando a acelerada expansão da Educação a Distância (EaD) no Brasil e os desafios que ainda enfrenta, torna-se importante dedicar um olhar cuidadoso sobre as questões envolvidas. Do ponto de vista da Psicologia, o foco no indivíduo que trabalha com EaD é fundamental. Neste contexto, destaca-se o trabalho do tutor, um recorte deste complexo mundo do trabalho em EaD, alvo deste estudo. O desempenho profissional do tutor depende de fatores tecnológicos, ambientais e psicossociais. Neste este estudo, o objetivo foi verificar o impacto que as crenças de autoeficácia no trabalho, a percepção de suporte social e o engajamento no trabalho exercem sobre o desempenho de tutores de disciplinas oferecidas a distância. A pesquisa teve caráter transversal e foi desenvolvida em uma universidade brasileira com sede no Estado de São Paulo. Os 227 tutores participantes atuavam em diferentes localidades do Brasil; 62% eram mulheres, 65% casados, 66% possuíam idades entre 25 e 45 anos e 97% cursou pelo menos especialização. A coleta dos dados foi realizada por meio eletrônico. Foram aplicadas escalas válidas e confiáveis de autoeficácia, engajamento e percepção de suporte social no trabalho, além de um questionário de dados sociodemográficos. Foi ainda realizada pesquisa documental para levantar informações sobre desempenho. Cálculos de médias, desvios-padrão, medianas e quartis revelaram que os tutores possuem bons níveis de autoeficácia, engajamento no trabalho e desempenho. Mais de 75% deles percebem ter acesso a informações suficientes e importantes, bem como contar com relacionamentos confiáveis e afetivos no trabalho, enquanto metade percebe dispor de bons insumos materiais, financeiros, técnicos e gerenciais. Resultados de análises de variância revelaram não haver diferenças entre desempenho de grupos que exercem outras atividades profissionais além da tutoria e os que não exercem, nem entre grupos que possuem e não possuem formação específica para atuar em tutoria em EaD. Resultados de regressões lineares múltiplas revelaram que as crenças de autoeficácia no trabalho, a percepção de suporte social e o engajamento no trabalho não explicam significantemente a variância do desempenho de tutores. Os resultados foram discutidos, sustentados principalmente na pequena variabilidade das notas de desempenho, considerando que 98,8% dos tutores obtiveram pontuação superior à média do instrumento de avaliação utilizado pela instituição, o que pode revelar dificuldades no processo de avaliação ou problemas relativos à validade do instrumento. Discutiram-se, além disso, questões relacionadas ao desempenho humano, como fenômeno complexo e multidimensional, buscando abordar o papel das variáveis do estudo em sua determinação, à luz da literatura especializada. Ao final, foram apresentadas implicações metodológicas, teóricas e práticas, bem como limitações do estudo e agenda de pesquisa.

Documentation of antibiotic prescribing controls in UK NHS hospitals

Objectives: To identify the types, prevalence and nature of antibiotic prescribing control documents within NHS hospitals in the UK. Methods: A self-completion postal questionnaire was sent to each Chief Pharmacist at 465 NHS hospitals in 2001/2002. This contained questions covering hospital demographics, and hospital antibiotic prescribing control documentation, including format, dissemination, approval and review processes. Results: In total, 253 (54%) completed questionnaires were returned. Of these, 168 respondents' hospitals had an antibiotic formulary, 107 had a policy for antibiotic prescribing and 216 had guidelines on antibiotic use. All three types of antibiotic prescribing documents were used by 82 hospitals but 18 did not have any documents; 44% of formularies, 45% of policies and 35% of guidelines were available electronically. The Drug and Therapeutics Committee was the most frequently cited body for document approval and approximately one-third of documents had been approved during the current year of the questionnaire. Only about one-half of responding hospitals had an annual review of documents. Conclusions: Despite publication of high-profile national guidance in response to growing concerns regarding antimicrobial resistance, there has been little increase in the use of antibiotic prescribing control documents in NHS hospitals over the past decade. It is clear that appropriate controls for antibiotic prescribing are not yet universally applied in the UK and recommendations for action have been proposed. © The British Society for Antimicrobial Chemotherapy 2004; all rights reserved.

Development and validaton of an indicator to compare antibiotic usage in secondary care in England

The use of antibiotics was investigated in twelve acute hospitals in England. Data was collected electronically and by questionnaire for the financial years 2001/2, 2002/3 and 2003/4. Hospitals were selected on the basis of their Medicines Management Self-Assessment Scores (MMAS) and included a cohort of three hospitals with integrated electronic prescribing systems. The total sample size was 6.65% of English NHS activity for 2001/2 based on Finished Consultant Episode (FCE) numbers. Data collected included all antibiotics dispensed (ATC category J01), hospital activity FCE's and beddays, Medicines Management Self-assessment scores, Antibiotic Medicines Management scores (AMS), Primary Care Trust (PCT) of origin of referral populations, PCT antibiotic prescribing rates, Index of Multiple Deprivation for each PCT. The DDD/FCE (Defined Daily Dose/FCE) was found to correlate with the DDD 100beddays (r = 0.74 p