Evolution Operators for Linearly Polarized Two-Killing Cosmological Models

We give a general procedure to obtain non perturbative evolution operators in closed form for quantized linearly polarized two Killing vector reductions of general relativity with a cosmological interpretation. We study the representation of these operators in Fock spaces and discuss in detail the conditions leading to unitary evolutions.Comment: Accepted for publication in Physical Review

Hamiltonian Dynamics of Linearly Polarized Gowdy Models Coupled to Massless Scalar Fields

The purpose of this paper is to analyze in detail the Hamiltonian formulation for the compact Gowdy models coupled to massless scalar fields as a necessary first step towards their quantization. We will pay special attention to the coupling of matter and those features that arise for the three-handle and three-sphere topologies that are not present in the well studied three torus case -in particular the polar constraints that come from the regularity conditions on the metric. As a byproduct of our analysis we will get an alternative understanding, within the Hamiltonian framework, of the appearance of initial and final singularities for these models.Comment: Final version to appear in Classical and Quantum Gravit

Examining the reciprocal relationship between bus rapid transit and the built environment in Latin America

There has been a rapid growth of Bus Rapid Transit (BRT) systems in the world over the last two decades with more than 200 cities currently with this type of transportation system. Empirical evidence of BRT’s effects on land use and development is still limited and its relationship with affordable housing is largely unexplored. Likewise, very few studies have examined the influence of the built environment on BRT ridership. The first aim of this dissertation examines land use and development impacts of BRT in Bogota and Quito using a multimethod approach. The quantitative approach estimates the average treatment effect of BRT on built-up area and land uses with a difference-in-difference research design. The analysis runs propensity score weighted regression models with treatment and control land parcels. In Bogota, parcels with BRT had a minimum effect on built-up area changes and mixed results regarding changes of residential and commercial uses in relation to control corridors. In Quito mixed results were found, with similarly positive and negative effects of the BRT on new developments in relation to the control corridor. The qualitative approach examined semi-structured interviews with key participants finding five themes explaining the mixed results of development impacts of BRT: coordination, expertise, development, management and equity issues. The second aim of this dissertation examines whether population density and built environment attributes explain ridership in a sample of 120 BRT stations in seven cities in Latin America. Results found no association between population density and BRT ridership but adding the built environment attributes around stations increased the explanatory power of the model. Two built environment factors as a result of factor analysis suggest high-rise multifamily developments, mixed uses and presence of facilities are positively associated with BRT ridership. Six BRT station typologies as a result of cluster analysis suggest transit oriented development features like non-motorized transport infrastructure play an important role explaining ridership. Based on this work, this dissertation recommends the implementation of BRT as urban development projects integrating land use and transportation planning with an equity perspective, and an assessment of built environment attributes around stations for predictions of BRT ridership.Doctor of Philosoph

The marine biogeography of Ragay Gulf and Burias Pass, Philippines

Ragay Gulf and Burias Pass are among the traditional fishing grounds of the country being considered by the government for an integrated approach to fishery management (Smith, et al., 1980; Samson, et al., 1977, World Bank, 1976). The Department of Marine Fisheries, College of Fisheries, University of the Philippines in the Visayas (UPV) in cooperation with the German Technical Cooperation Agency (GTZ), and under the financial auspices of the National Science and Technology Authority (NSTA) and the Ministry of Natural Resources (MNR), was awarded a contract to do a multidisciplinary research survey of the area from November, 1981 to February, 1983 under the aegis of the NSTA-MNR-UPVCF Project no. 8203 Ag. "Assessment of Trawlable Areas in the Philippines II- Ragay Gulf, Burias Pass, Ticao Pass, and Waters North of Samar Sea." To date, much of what remains to be done involves the processing and analyses of the volumes of research data accumulated by this project. The main objective of the above research was to assess the status of the fishery resources of the area for the rational management of the commercial and subsistence fishing industry. However, much of the basic information generated by this multidisciplinary research can be used for other purposes as well. This paper is a contribution to this extensive research effort. Specifically, the objectives of this research are as follows: 1) to understand the seasonal monsoons and local topography and how they affect the environmental processes and patterns in Ragay Gulf and Burias Pass, 2) to determine the biogeographic distribution of ichthyoplankton in the Ragay Guif-Burias Pass area and their relationship with their fluid environment, and 3) based on the above fmdings, identify potential sites that are suitable for the establishment of fish sanctuaries

Unitary evolution of free massless fields in de Sitter space-time

We consider the quantum dynamics of a massless scalar field in de Sitter space-time. The classical evolution is represented by a canonical transformation on the phase space for the field theory. By studying the corresponding Bogoliubov transformations, we show that the symplectic map that encodes the evolution between two instants of time cannot be unitarily implemented on any Fock space built from a SO(4)-symmetric complex structure. We will show also that, in contrast with some effectively lower dimensional examples arising from Quantum General Relativity such as Gowdy models, it is impossible to find a time dependent conformal redefinition of the massless scalar field leading to a quantum unitary dynamics.Comment: 20 pages. Comments and references adde

El acceso a los servicios de salud bucodental para la población adulta mayor en la red hospitalaria pública de Medellín (Colombia)

Antecedentes/Objetivos: La población adulta mayor es un grupo poblacional significativo teniendo en cuenta los cambios demográficos de las últimas décadas. En el país y en la ciudad de Medellín, este grupo presenta alta vulnerabilidad social, así mismo se observan necesidades en salud bucal, descritas en los estudios nacionales y regionales en el tema. Aunque se han realizado investigaciones que tratan de identificar determinantes que afectan el acceso y la utilización de los servicios de salud, los estudios en salud bucal son más escasos y en especial en la población adulta mayor. Objetivo: identificar barreras y facilitadores de acceso a los servicios de salud bucal en población adulta mayor atendida en la red hospitalaria pública de Medellín desde la perspectiva del personal de salud. Métodos: Estudio cualitativo. Se realizaron 34 entrevistas semiestructuradas en personal que presta servicios de salud en la red Metrosalud de Medellín. Se identificaron barreras y facilitadores según el modelo de Tanahashi sobre cobertura en los servicios de salud a través de 4 categorías: disponibilidad (D), accesibilidad (A), aceptabilidad (P) y contacto con el servicio (C). Se utilizó la herramienta informática AtlasTi. Resultados: Se identificaron barreras relacionadas con: dificultades en la implementación de políticas sociales debido a que la salud bucal no es una prioridad; se han priorizado otras poblaciones para dar atención en salud bucal y existe insuficiente recurso humano para prestar los servicios de salud (D); la situación de discapacidad de los adultos mayores (A); aspectos educativos, culturales y de género (P); y la crisis del sector salud como una barrera estructural del sistema (C). En cuanto a los facilitadores se mencionan: la existencia de programas que facilitan la demanda inducida a programas de salud bucal y de mecanismos para hacer valer los derechos en salud a través de instancias gubernamentales y otras (D); la ubicación de las unidades y centros de salud en zonas de fácil acceso (A); la capacidad de los profesionales para atender esta población (P) y la articulación de la odontología con otras áreas (C). Conclusiones: Se identificaron determinantes que afectan el acceso a servicios sanitarios en la población adulta mayor, por lo que se requieren estrategias para mejorar la calidad de la atención en salud bucal en este grupo socialmente vulnerable.E.S.E Metrosalud. Medellín (Código: C02-E11-L3-01)

Viability and Burden of Leishmania in Extralesional Sites during Human Dermal Leishmaniasis

Understanding of the dynamics and distribution of Leishmania in the human host is fundamental to the targeting of control measures and their evaluation. Amplification of parasite gene sequences in clinical samples from cutaneous leishmaniasis patients has provided evidence of Leishmania in blood, other tissues and sites distinct from the lesion and of persistence of infection after clinical resolution of disease. However, there is uncertainty about the interpretation of the presence of Leishmania DNA as indicative of viable parasites. Because RNA is short-lived and labile, its presence provides an indicator of viability. We amplified Leishmania 7SLRNA, a molecule involved in intracellular protein translocation, to establish viability and estimate parasite load in blood monocytes, tonsil swab samples, and tissue fluid from healthy skin of patients with dermal leishmaniasis. Results showed that during active dermal leishmaniasis, viable Leishmania are present in blood monocytes, tonsils and normal skin in quantities similar to that in lesions, demonstrating widespread dissemination of infection and subclinical involvement of tissues beyond the lesion site. Leishmania 7SLRNA will be useful in deciphering the role of human infection in transmission

Quantization of Midisuperspace Models

We give a comprehensive review of the quantization of midisuperspace models. Though the main focus of the paper is on quantum aspects, we also provide an introduction to several classical points related to the definition of these models. We cover some important issues, in particular, the use of the principle of symmetric criticality as a very useful tool to obtain the required Hamiltonian formulations. Two main types of reductions are discussed: those involving metrics with two Killing vector fields and spherically symmetric models. We also review the more general models obtained by coupling matter fields to these systems. Throughout the paper we give separate discussions for standard quantizations using geometrodynamical variables and those relying on loop quantum gravity inspired methods.Comment: To appear in Living Review in Relativit

Prospects for progress on health inequalities in England in the post-primary care trust era : professional views on challenges, risks and opportunities

Background - Addressing health inequalities remains a prominent policy objective of the current UK government, but current NHS reforms involve a significant shift in roles and responsibilities. Clinicians are now placed at the heart of healthcare commissioning through which significant inequalities in access, uptake and impact of healthcare services must be addressed. Questions arise as to whether these new arrangements will help or hinder progress on health inequalities. This paper explores the perspectives of experienced healthcare professionals working within the commissioning arena; many of whom are likely to remain key actors in this unfolding scenario. Methods - Semi-structured interviews were conducted with 42 professionals involved with health and social care commissioning at national and local levels. These included representatives from the Department of Health, Primary Care Trusts, Strategic Health Authorities, Local Authorities, and third sector organisations. Results - In general, respondents lamented the lack of progress on health inequalities during the PCT commissioning era, where strong policy had not resulted in measurable improvements. However, there was concern that GP-led commissioning will fare little better, particularly in a time of reduced spending. Specific concerns centred on: reduced commitment to a health inequalities agenda; inadequate skills and loss of expertise; and weakened partnership working and engagement. There were more mixed opinions as to whether GP commissioners would be better able than their predecessors to challenge large provider trusts and shift spend towards prevention and early intervention, and whether GPs’ clinical experience would support commissioning action on inequalities. Though largely pessimistic, respondents highlighted some opportunities, including the potential for greater accountability of healthcare commissioners to the public and more influential needs assessments via emergent Health & Wellbeing Boards. Conclusions - There is doubt about the ability of GP commissioners to take clearer action on health inequalities than PCTs have historically achieved. Key actors expect the contribution from commissioning to address health inequalities to become even more piecemeal in the new arrangements, as it will be dependent upon the interest and agency of particular individuals within the new commissioning groups to engage and influence a wider range of stakeholders.</p

Arnis-based Exercise Program for Balance Control in Community-Dwelling Older Adults: Study Protocol for a Pilot Randomized Controlled Trial

Background: Aging causes impairment in balance and increases the prevalence of falls in older adults. Martial arts are now incorporated into exercise programs to improve balance. Arnis, a Filipino Martial Art, can improve the balance control of older adults. Objectives: This study primarily aims to determine the effects of an Arnis-based exercise program on balance control of healthy community-dwelling older adults. This study also aims to describe its effect on older adults’ concerns about falling and lower limb functional strength. Methods:This will be a single-blind, pilot randomized controlled trial. Participants will be randomly allocated to either the intervention or control group. The intervention group will perform an Arnis-based exercise program for 40-60 minutes per session thrice a week for 12 weeks. The control group will continue to do their usual activities for the duration of the study. Participants will be measured at baseline and 12 weeks after for balance, concern for falling, and lower limb strength using the Berg Balance Scale, Timed-Up and Go Test, Falls Efficacy Scale-International Filipino, and the 30-second Chair Sit-to-stand Test, respectively. Data will be analysed through independent and paired t-tests. A p-value Expected Results: Significant improvements in the balance scores in the intervention group are expected after 12 weeks of the Arnis-based exercise program, along with its effects on concerns for falling and lower extremity strength. The pilot study will provide data on the effectiveness of Arnis as a reference for future larger experimental studies