Relativistic quark models and the current algebra

In this thesis we are concerned with finding representations of the algebra of SU(3) vector and axial-vector charge densities at infinite momentum (the "current algebra") to describe the mesons, idealizing the real continua of multiparticle states as a series of discrete resonances of zero width. Such representations would describe the masses and quantum numbers of the mesons, the shapes of their Regge trajectories, their electromagnetic and weak form factors, and (approximately, through the PCAC hypothesis) pion emission or absorption amplitudes.

We assume that the mesons have internal degrees of freedom equivalent to being made of two quarks (one an antiquark) and look for models in which the mass is SU(3)-independent and the current is a sum of contributions from the individual quarks. Requiring that the current algebra, as well as conditions of relativistic invariance, be satisfied turns out to be very restrictive, and, in fact, no model has been found which satisfies all requirements and gives a reasonable mass spectrum. We show that using more general mass and current operators but keeping the same internal degrees of freedom will not make the problem any more solvable. In particular, in order for any two-quark solution to exist it must be possible to solve the "factorized SU(2) problem," in which the currents are isospin currents and are carried by only one of the component quarks (as in the K meson and its excited states).

In the free-quark model the currents at infinite momentum are found using a manifestly covariant formalism and are shown to satisfy the current algebra, but the mass spectrum is unrealistic. We then consider a pair of quarks bound by a potential, finding the current as a power series in 1/m where m is the quark mass. Here it is found impossible to satisfy the algebra and relativistic invariance with the type of potential tried, because the current contributions from the two quarks do not commute with each other to order 1/m³. However, it may be possible to solve the factorized SU(2) problem with this model.

The factorized problem can be solved exactly in the case where all mesons have the same mass, using a covariant formulation in terms of an internal Lorentz group. For a more realistic, nondegenerate mass there is difficulty in covariantly solving even the factorized problem; one model is described which almost works but appears to require particles of spacelike 4-momentum, which seem unphysical.

Although the search for a completely satisfactory model has been unsuccessful, the techniques used here might eventually reveal a working model. There is also a possibility of satisfying a weaker form of the current algebra with existing models.

Polychaetous annelids (order Sabellida) from the Karachi coast, Pakistan

Fifteen species of polychaete worms, belonging to order Sabellida, are described from the Karachi coast. Of these 10 are new records for Pakistan: Hydroides albiceps (Grube, 1870), H. exaltatus (Marenzellar, 1885), Protula sp. Spirobranchus tetraceros (Schmarda, 1861), Vermiliopsis infundibulum glandigera group, Demonax sp. and Bispira cf tricyclia (Schmarda, 1861).

Divorce deals and bankruptcy

Discusses the rights and responsibilities of trustees and beneficiaries of co-owned land under the Trusts of Land and Appointment of Trustees Act 1996, in particular s.14 which allows the court to make an order declaring the extent and nature of a person's interest in the property. Refers to the Court of Appeal decision in Avis v Turner on whether the existence of an earlier court order postponing the sale of matrimonial property following the owners' divorce meant that an application could not be brought by a trustee in bankruptcy under s.14. Considers the "exceptional circumstances" which could allow the court to postpone the sale. [From Legal Journals Index]

Fixed versus Flexible: lessons from EMS order Flow

We extend the literature on regime-dependent volatility in two ways. First, our microstructural model provides a qualitatively new explanation. Second, we test implications of our model using Europe's recent shift to rigidly fixed rates (EMS to EMU). In the model, shocks to order flow induce more volatility under flexible rates because the elasticity of speculative demand is (endogenously) low, leading to pronounced portfolio-balance effects. New data on FF/DM transactions show that order flow had persistent effects on the exchange rate before EMU parities were announced. After announcement, the FF/DM rate was decoupled from order flow, as the model predicts.

Evidence-Based Clinical Pathways To Manage Urinary Tract Infections in Long-Term Care Facilities:A Qualitative Case Study Describing Administrator and Nursing Staff Views

Objectives: This article examines the views of nursing staff and administrators in long-term care facilities (LTCFs) regarding a clinical pathway for managing urinary tract infections (UTIs) in LTCF residents. Design: A qualitative (case study) design was used. Setting: Data were collected from 8 LTCFs in southern Ontario and 2 in Iowa enrolled in a larger randomized controlled trial of clinical pathway for managing UTIs in LTCF residents, conducted between September 2001 and March 2003. The clinical pathway, designed to more effectively identify, diagnose, and treat UTIs, and reduce inappropriate antibiotics use for asymptomatic UTIs, introduced 2 decision tools to determine when to order a urine culture and initiate antibiotic treatment for suspected UTIs. Participants: We conducted 19 individual interviews with administrators and 10 focus groups with 52 nurses. Findings: Nurses generally thought that the pathways were well developed and easy to use, and administrators believed they were an important educational resource. Barriers to their use varied by group-initial lack of buy-in from nurses (medical directors), additional work (directors of nursing), and the need to change the protocol to exclude certain residents based on prior health conditions and/or pressure from physicians or families (nurses). Conclusions: Both administrators and staff, once familiar with a new clinical protocol to improve UTI management in LTCFs, generally supported its use. © 2007 American Medical Directors Association.

Predictability in high-stakes examinations: students' perspectives on a perennial assessment dilemma

Key debates within educational assessment continuously encourage us to reflect on the design, delivery and implementation of examination systems as well as their relevance to students. In more recent times, such reflections have also required a rethinking of who is authoritative about assessment issues and whose views we seek in order to better understand these perennial assessment dilemmas. This paper considers one such dilemma, predictability in high-stakes assessment, and presents students’ perspectives on this issue. The context is the Irish Leaving Certificate (LC) taken by upper secondary students (aged between 16 and 18) in order (mainly) to enter tertiary-level education. The data come from 13 group interviews with 81 students across a range of schools in Ireland. Listening to students about complex, high-stakes examining problems has a limited history within the educational assessment literature. The findings from the study address this shortcoming and depict how students’ insightful reflections can improve our understanding of these dilemmas. Further, students are more than able to reflect on their own situations with regard to high stakes examining contexts and have important contributions to make to our fuller understanding of those elements that will promote high quality and fair assessment.

Contribution of biobanks to care services

Approaches to the management of patients with cancer have been revolutionised by the ability to examine tumours at a genetic and molecular level and tailor treatments accordingly. Underpinning this work is the need for large numbers of high-quality human biospecimens for use in translational research studies to identify new biomarkers for the prediction, diagnosis and treatment of cancer. Biobanking has subsequently emerged as a dedicated activity to provide the infrastructure required for the standardised collection, storage and distribution of high quality human biospecimens for research purposes. This article provides an overview of the role of biobanks and the vital contribution they make to the delivery of cancer care for patients now and in the future

Using VEs to enhance chronological understanding of history in middle school children.

Studies with computer-experienced children in the UK and less experienced in Ukraine explored the potential for VEs in teaching historical chronology to middle-school children aged 10–12 years old. Active fly-through VEs had been previously used successfully with primary school children aged 8–9 years old (given specific training with the environment) when they were subsequently tested for their ability to order events chronologically. All VEs in the present studies included a training element and active challenge, both found previously to enhance learning in other age groups. Ukraine children were trained and tested. UK children here were trained and tested, then retrained and retested to examine savings. Unlike other age groups, no significant benefit was seen for VE training compared with PowerPoint and Text conditions in either study. Possible explanations for the ineffectiveness of VE training for children of middle school age will be discussed. Keywords: timeline, chronographics

Validação de uma escala de atitudes de alunos relativamente ao uso de uma plataflrma de ensino ao longo da vida

Dissertação de Mestrado, Ciências da Educação, Área de Especialização de Educação e Formação de Adultos, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2007

Gestão de stocks aplicada a uma instituição de saúde privada

A gestão de stocks tem-se tornado uma ferramenta fundamental na racionalização de custos das empresas permitindo uma maior eficiência operacional. Os modelos de gestão de stocks procuram ajudar a determinar as quantidades a encomendar e quando encomendar, com um custo total de aprovisionamento mínimo. Este trabalho visa o estudo da gestão de stocks, dos modelos existentes e a aplicação de um deles num prestador de saúde, em particular, na área da imagiologia. Neste estudo optou-se por efectuar a classificação ABC dos produtos e posteriormente procurou-se definir o modelo de gestão de stocks que melhor se adeqúe à realidade empresarial em estudo de modo a manter o nível de stock correcto associado a um menor custo. Optou-se pelo modelo de revisão periódica de stocks que permite efectuar a encomenda sempre com o mesmo intervalo de tempo e efectuar ajustes nas quantidades necessárias. Com base nos dados fornecido efectuou-se uma previsão da procura e assim definiram-se as quantidades a encomendar, bem como o stock de segurança necessário. Implementaram-se as quantidades e o stock de segurança e efectuou-se uma avaliação dos resultados obtidos e analisou-se o impacto da gestão de stocks no prestador de saúde.

Acção do vento em pontes: estudo comparativo RSA/NP EN 1991-1-4

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Estruturas

Application of [Lambda] to the fourth perturbation theory in calculating the equation of state of rare gas solids and fcc metals

We have calculated the thermodynamic properties of monatomic fcc crystals from the high temperature limit of the Helmholtz free energy. This equation of state included the static and vibrational energy components. The latter contribution was calculated to order A4 of perturbation theory, for a range of crystal volumes, in which a nearest neighbour central force model was used. We have calculated the lattice constant, the coefficient of volume expansion, the specific heat at constant volume and at constant pressure, the adiabatic and the isothermal bulk modulus, and the Gruneisen parameter, for two of the rare gas solids, Xe and Kr, and for the fcc metals Cu, Ag, Au, Al, and Pb. The LennardJones and the Morse potential were each used to represent the atomic interactions for the rare gas solids, and only the Morse potential was used for the fcc metals. The thermodynamic properties obtained from the A4 equation of state with the Lennard-Jones potential, seem to be in reasonable agreement with experiment for temperatures up to about threequarters of the melting temperature. However, for the higher temperatures, the results are less than satisfactory. For Xe and Kr, the thermodynamic properties calculated from the A2 equation of state with the Morse potential, are qualitatively similar to the A 2 results obtained with the Lennard-Jones potential, however, the properties obtained from the A4 equation of state are in good agreement with experiment, since the contribution from the A4 terms seem to be small. The lattice contribution to the thermal properties of the fcc metals was calculated from the A4 equation of state, and these results produced a slight improvement over the properties calculated from the A2 equation of state. In order to compare the calculated specific heats and bulk moduli results with experiment~ the electronic contribution to thermal properties was taken into account~ by using the free electron model. We found that the results varied significantly with the value chosen for the number of free electrons per atom.

A treatment of atomic mean square displacement in higher order perturbation theory

A general derivation of the anharmonic coefficients for a periodic lattice invoking the special case of the central force interaction is presented. All of the contributions to mean square displacement (MSD) to order 14 perturbation theory are enumerated. A direct correspondance is found between the high temperature limit MSD and high temperature limit free energy contributions up to and including 0(14). This correspondance follows from the detailed derivation of some of the contributions to MSD. Numerical results are obtained for all the MSD contributions to 0(14) using the Lennard-Jones potential for the lattice constants and temperatures for which the Monte Carlo results were calculated by Heiser, Shukla and Cowley. The Peierls approximation is also employed in order to simplify the numerical evaluation of the MSD contributions. The numerical results indicate the convergence of the perturbation expansion up to 75% of the melting temperature of the solid (TM) for the exact calculation; however, a better agreement with the Monte Carlo results is not obtained when the total of all 14 contributions is added to the 12 perturbation theory results. Using Peierls approximation the expansion converges up to 45% of TM• The MSD contributions arising in the Green's function method of Shukla and Hubschle are derived and enumerated up to and including 0(18). The total MSD from these selected contributions is in excellent agreement with their results at all temperatures. Theoretical values of the recoilless fraction for krypton are calculated from the MSD contributions for both the Lennard-Jones and Aziz potentials. The agreement with experimental values is quite good.

Exploring the experience of the pioneers of change

The world of work with Western society appears to be undergoing a major change. The literature has described this phenomenon as a change from an industrialbased economy to a knowledge-based economy. This change will represent a complete transformation of the world of work; some suggest that everything we have come to accept and know as normal will change. Our present society seems to be in a period of transition. It is a time with many challenges and problems, many of which cannot be solved with thinking patterns from an old industrial-based economy. A fundamental shift in thinking patterns consistent with a new emerging world of work must take place. This change in thinking represents a fundmental shift from traditional and linear ways of seeing the world (worldview), to more holistic ways of seeing the world. In this investigation the word paradigm was used to define how people see their world. A paradigm shift is defined as a change in how a person sees their world: a change from an old to new or different way of viewing the world. Those individuals who are the first to shift their paradigm are called paradigm pioneers. These individuals do not only shift their ways of seeing the world, but they also begin to act and behave in ways consistent with the new paradigm. Thus far the research literature has adequately described the concepts of paradigms and paradigm shifts. However, little is known regarding how people actually and eventually make a shift. As it will be important for each individual to make a personal paradigm shift, then it will be extremely valuable to learn more about the process itself. The purpose of this investigation was to explore these issues in more detail and specifically, describe the experience of paradigm shifts and explore the experience of paradigm pioneers. A qualitative research methodology involving in-depth interviews was used to investigate the experiences of four participants identified as paradigm pioneers. It is interesting to note that the participants in this study did not describe an allencompassing paradigm shift. In fact, each participant, defined a paradigm shift in several different ways. They did relate several examples of paradigm shifts. However, even among these examples, there was a high degree of variability. The findings of this investigation centered upon the participants' experience as pioneers. Each pioneer shared many of the same qualities, the first quality of which described how these pioneers dealt with change. I called this a change-sense quality. The pioneers viewed change in an open and positive manner, and were also aware of change taking place in their world. Finally, they displayed an understanding of change, and a bias to take positive action in the face it. The participants also shared an inner quality. The four pioneers demonstrated a personal purpose and vision, and were selfdirected individuals. They also had an innate curiosity which translated into a love of learning. They also displayed a quality where relationships with others were highly valued. Relationships were important to the pioneers because they played a support role to help them deal with the challenges of being a pioneer. Pioneers also valued relationships because, they relied on others to make change happen. The above mentioned qualities enabled pioneers to be effective in a changing world of work. The findings from this investigation have many implications for research and practice. First, the concept of paradigms and paradigm shifts must be further researched. A great deal more must be learned in order to better understand the kind of shift individuals must make to be effective in the new world of work. Second, the qualities displayed by pioneers are important for all members of the world of work to develop. The qualities shared by pioneers appeared to represent an enduring set of traits that can possibly help individuals deal more positively with uncertainty and rapid change taking place in today's North American world of work.

Youth Involvement in Organizational Decision Making: The Connection to Youth Initiative and Organizational Functioning

Studying positive adolescent development requires an examination of the mutually beneficial associations between youth and their environment. These youthcontext relations include both the contributions that youth make to others and society and the youth-context interactions that might predict positive youth outcomes. Community and youth-serving organizations, where youth may be involved in decision-making roles such as service delivery, advocacy, or on boards of directors, can provide one important context for youth contributions and for positive adolescent development. Research on the outcomes of youth involvement in organizational decision-making, however, is limited, and largely consists of exploratory qualitative studies. This dissertation is formatted as an integrated article dissertation. It begins with a review of the literature on contexts of structured youth activities and positive youth development. This review is intended to describe theory on development-context relations, in which development is considered an interactive process that occurs between individuals and their contexts, as it pertains the positive development of youth who are involved in various structured activities (e.g., volunteering). This description follows with a review of current research, and conclusions and rationale for the current studies. Following this theoretical and research background, the dissertation includes reports of two studies that were designed to address gaps in the research on youth involvement in organizational decision-making. The first was a qualitative research synthesis to elucidate and summarize the extant qualitative research on the outcomes of youth involvement in organizational decision making on adults and organizations. Results of this study suggested a number of outcomes for service provision, staff, and broader organizational functioning, including both benefits to organizations as well as some costs. The second study was a quantitative analysis of the associations among youth involvement, organizations' learning culture, and youth initiative, and relied on survey data gathered from adults and youth in community-based organizations with youth involvement. As expected, greater youth involvement in organizational decision making was associated with higher learning culture within the organization. Two dimensions of youth involvement, greater program engagement and relationships with adults, were related to greater youth initiative. A third dimension, sense of ownership, was not- .-.- associated with youth's level of initiative. Moreover, the association between relationships with adults and youth initiative was only significant in organizations with relatively low learning culture. Despite some limitations, these studies contribute to the research literature by providing some indication of the potential benefits and costs of youth involvement and by making an important contribution toward the early stages of context-level analyses of youth development. Findings have important implications for practitioners, funders, future research, and lifespan development theory.