1,144 research outputs found
Dynamical evolution of rotating dense stellar systems with embedded black holes
Evolution of self-gravitating rotating dense stellar systems (e.g. globular
clusters, galactic nuclei) with embedded black holes is investigated. The
interaction between the black hole and stellar component in differential
rotating flattened systems is followed. The interplay between velocity
diffusion due to relaxation and black hole star accretion is investigated
together with cluster rotation using 2D+1 Fokker-Planck numerical methods. The
models can reproduce the Bahcall-Wolf solution () inside the zone of influence of the black hole. Gravo-gyro and
gravothermal instabilities conduce the system to a faster evolution leading to
shorter collapse times with respect to the non-rotating systems. Angular
momentum transport and star accretion support the development of central
rotation in relaxation time scales. We explore system dissolution due to
mass-loss in the presence of an external tidal field (e.g. globular clusters in
galaxies).Comment: 16 pages, 23 figures, 6 table
The glycoprotein gp350 of EBV - an in vivo antigen and a promising druggable target molecule
Epstein-Barr virus (EBV) infects more than 90% of the human population worldwide. The virus is directly responsible for acute infectious mononucleosis (IM), and is related to several malignancies like Hodgkin lymphoma (HL), Burkitt lymphoma (BL), nasopharyngeal carcinoma (NPC) and posttransplant lymphoproliferative diseases (PTLD). EBV is also associated with various autoimmune diseases like Multiple Sclerosis (MS).
The present work aimed at investigating the biology of EBV in long-term infected healthy carriers, thereby focusing on the expression of the lytic envelope glycoprotein gp350. The protein is well known for its crucial role for the viral infection of human B cells and is therefore considered an attractive target for therapeutic approaches, and also a vaccine candidate. The first part of this thesis was dedicated to investigating the presence of gp350 and its potential role in vivo. Since gp350-specificic antibodies can be detected life-long in EBV seropositive individuals, there might be a constant trigger of the immune system by gp350. This hypothesis was corroborated by my observation that certain latently EBV infected cell lines express significant amounts of gp350 on the cell surface and/or release it via extracellular vesicles (EVs). Moreover, I could show for the first time that the gp350 protein is present on a subset of B cells from healthy EBV-seropositive donors, and that the protein is also present in sera. Intriguingly, I could observe a direct correlation between antibody and protein titers. Moreover, I could show that gp350 carrying vesicles isolated from donors reactivate autologous gp350-specific CD4+ T cells, implicating a potential immunological function, e.g., in maintaining viral latency and stable co-existence with the host. This is the first time that gp350 was detected in the blood of healthy donors. Additional studies are needed to elucidate its origin, exact status and biological function.
Therapeutic monoclonal antibodies are a success story in modern medicine. Of particular potential are fully human IgG antibodies which combine the unprecedented specificities of antibodies with a very low immunogenicity. However, fully human antibodies targeting gp350 are not existent. In the second part of this thesis, we therefore developed a new technique to generate fully human IgG antibodies in humanized mice in collaboration with Prof. R. Stripecke (Med. Hochschule Hannover). These humanized mice were immunized with Epstein-Barr-virus like particles (EB-VLPs), and splenocytes were then immortalized with EBV in vitro. The supernatants of the EBV immortalized B cells were tested for human gp350-specific antibodies with neutralizing potential. The most promising antibody from the biological and neutralization assays was cloned. The immunoglobulin sequence was obtained, and classified the antibody as human IgG3, an Ig class strongly related with infectious diseases. The collaboration with the Stripecke lab resulted in the first fully human IgG antibodies generated in humanized mice.
In summary, the present study showed for the first time that gp350 is present in sera from EBV-positive healthy carriers without previous viral reactivation. Moreover, this protein is able to reactivate specific cellular immune responses. Finally, a fully human IgG3 gp350-specific antibody was produced, that may be developed into a therapeutic tool for the treatment of EBV-associated diseases
Integrity, restricted competition and Covid-19: challenges for Peruvian public procurement.
Sistematizar la evidencia sobre el efecto de la carne y derivados en el riesgo de aparición de cáncer. Material y Métodos: Se crearon algoritmos de búsqueda y fue aplicado a las bases de datos PubMed, Cochrane y tripdatabaseTrabajo Académic
Essays in ‘global’ health utilization: How distance, gender, and stigma condition whether and when we seek care
The landscape of health service use varies across, and even within, countries and health sectors irrespective of payment model or health system, yet the fundamental purpose motivating its study is aimed at overcoming the challenges that prevent better and equitable uptake of effective interventions. This dissertation is fuelled by such purpose. Although each chapter poses a specific utilization question relevant to a unique target population, in its entirety, this work seeks to answer the following cross-cutting questions: (i) what are the factors that encourage and challenge utilization of health services, (ii) under which moderating conditions and through which channels is improved utilization supported, and (iii) how can a better understanding of the antecedents of improved utilization contribute to the design of well-targeted health interventions. In Chapter 1, we show that participation in health insurance increases the probability of meeting medical needs while decreasing the probability of incurring catastrophic out-of-pocket health payments in Ghana. Drawing on nationally representative survey data from India, Chapter 2 offers causal insight into the effect of female empowerment, in the form of marital age, on women’s utilization of cervical and breast screening. Our findings suggest that losses in female empowerment attributed to early marriage partly explain Indian women’s low cervical and breast screening participation. Aiming to contribute a better understanding of health utilization among hard-to-reach groups, Chapter 3 investigates the factors that determine the extent of thought given to screening in a sample of high-risk heavy smokers who attended the first free lung cancer screening program in Italy. We show that individuals with greater life-time smoking exposure, and therefore at higher risk of developing lung cancer, tend to contemplate screening less. Finally, Chapter 4 evaluates the cost-effectiveness of a population-based lung cancer screening program targeting high-risk prior and current heavy smokers (≥20 pack-years) aged between 55 and 74 years, in Italy. In doing so, we explore the economic relevance of programs designed with a view towards improving screening participation within hard-to-reach target populations. We offer evidence that rendering an annual LDCT-based screening – with three varying screening invitation strategies – available to the Italian heavy smoker population is more effective, yet more costly, than current clinical practice from the perspective of the national budget holder. Thus, in seeking to offer insight into the factors that encourage and challenge utilization, the conditions and channels that sustain it, and the design of programs that may, in turn, be sustained by it, this dissertation positions health utilization at centre stage
Dos mil años de fe: luces y sombras en la larga historia de la Iglesia (Reseña)
Reseña del libro de Guillermo PONS PONS, Dos mil años de fe: luces y sombras en la larga historia de la Iglesia, Eunate («Raíces y hojas» 5), Pamplona 1997,417 p
Mejoramiento del servicio de agua para riego del canal Yéncala león de los distritos Lambayeque y San José, provincia y departamento de Lambayeque
El presente trabajo de investigación, titulada: “MEJORAMIENTO DEL SERVICIO DE AGUA PARA RIEGO DEL CANAL YÉNCALA LEÓN DE LOS DISTRITOS LAMBAYEQUE Y SAN JOSÉ, PROVINCIA Y DEPARTAMENTO DE LAMBAYEQUE”, tiene como objetivo general el mejoramiento del canal Yéncala León, diagnosticando su situación actual, se concluyó que existen pérdidas de agua por infiltración debido a que el canal existente es de tierra y no cumple las características fundamentales de un canal. Se realizaron los estudios básicos correspondientes como la Topografía, estudio de Mecánica de Suelos, entre otros., con los resultados se procedió a determinar y diseñar las diferentes obras de arte que se necesitan, apoyándonos en los respectivos cálculos matemáticos, que nos permiten asegurar infraestructuras hidráulicas eficientes y estructuralmente seguras, para su eficaz operación. Concluyendo: se revestirá un total de 5,560 m. lineales de canal, y diferentes obras de arte (puentes peatonales, compuertas, etc.), beneficiando a 190 usuarios de agua de riego que irrigan un total de 337.34 has. Según la ingeniería de costos del proyecto, el monto para la ejecución del proyecto es de S/ 3’982,699.49 nuevos soles. Monto que incluye la formulación del expediente técnico y el estudio de impacto ambiental; el desarrollo de la infraestructura, y supervisión de la obra
Implementación de un sistema web para el registro de bitácoras de maquinaria pesada en la Empresa Corporación Imperio & CAN E.I.R.L. Sechura, 2019
La investigación tuvo como objetivo general implementar un sistema web para el
registro de bitácoras de maquinaria pesada en la Corporación Imperio y CAN
E.I.R.L – Sechura, cuyo producto tecnológico fue desarrollado en lenguaje de
programación PHP junto con la tecnología de JavaScript y TypeScript combinado
con el framework Codeigniter e Ionic, conectado a un gestor de base de datos
MySQL. Para el desarrollo del sistema web se utilizó la Metodología RUP (Rational
Unified Process o Proceso Unificado de Racional) que es un marco de referencia
de ingeniería de software para definir tareas y responsabilidades dentro de un grupo
de desarrollo de software.
Siendo el tipo de investigación experimental de nivel explicativo, el sistema web fue
orientada a realizar registros, búsquedas y emisor de reportes de bitácoras de
maquinaria pesada en la empresa Corporación Imperio & CAN E.I.R.L de Sechura,
siendo 25 trabajadores la muestra de población para la investigación, de las cuales
fueron participes de guías de observación y lista de cotejo, instrumentos que se
utilizaron para analizar y obtener datos antes y después de la ejecución del sistema
web en dicha empresa y determinar cuáles fueron las mejoras después de la
implementación del sistema para finalmente comparar ambas informaciones.
Según los resultados obtenidos señalan que antes de implementar el sistema web
se logró observar que el tiempo promedio de registros de las bitácoras fue de 14.65
minutos y con el sistema propuesto fue de 4.74; el tiempo promedio de búsqueda
de información de una bitácora en su momento fue de 275.07 segundos y con el
sistema se redujo a 66.93 segundos; el promedio para emitir reportes de bitácoras
en su primer momento antes de la implementación del sistema web fue de 8.77
minutos y con el sistema fue de 2.29 minutos, por último se midió los requerimientos
de calidad necesarios para que el sistema web cumpla de las características de
adecuación funcional, usabilidad, fiabilidad y seguridad establecidos por la ISO
9126. Teniendo un puntaje del 0 al 50, obteniendo el 40.12 (bueno), que por lo tanto
el sistema web cumple con los requerimientos establecidos por la ISO 9126
2D Fokker-Planck models of rotating clusters
Globular clusters rotate significantly, and with the increasing amount of
detailed morphologicaland kinematical data obtained in recent years on galactic
globular clusters many interesting features show up. We show how our
theoretical evolutionary models of rotating clusters can be used to obtain
fits, which at least properly model the overall rotation and its implied
kinematics in full 2D detail (dispersions, rotation velocities). Our simplified
equal mass axisymmetric rotatingmodel provides detailed two-dimensional
kinematical and morphological data for star clusters. The degree of rotation is
not dominant in energy, but also non-negligible for the phase space
distribution function, shape and kinematics of clusters. Therefore the models
are well applicable for galactic globular clusters. Since previously published
papers on that matter by us made it difficult to do detailed comparisons with
observations we provide a much more comprehensive and easy-to-use set of data
here, which uses as entries dynamical age and flattening of observed cluster
andthen offers a limited range of applicable models in full detail. The method,
data structure and some exemplary comparison with observations are presented.
Future work will improve modelling anddata base to take a central black hole, a
mass spectrum and stellar evolution into account
- …