Giant vesicles compressed by actin polymerization

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 45-46).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Actin polymerization plays a critical role in generating propulsive force to drive many types of cell motility. The discovery of actin based motility of the bacterial pathogen Listeria monocytogenes has lead to clearer understandings of the essential ingredients required for cell motility. The biophysical mechanisms by which these proteins generate forces is the subject of intense investigation. A novel system to study force generation by this polymerization engine is introduced by combining the well characterized mechanical properties of synthetic Giant Vesicles with the well understood biochemistry of actin polymerization. Giant Vesicles mimic the structural features of eukaryotic cell membranes. We find that Giant Vesicles coated with a protein that catalyzes actin polymerization form thick actin shells which produce a compressive force. The polymerization force directed at the membrane interface causes the membrane to rupture. In the resulting collapse we find that the shell thickens inward with a constant radial velocity and is characterized by radial lines of lipid and actin. We show that actin polymerization is the primary force driving the collapse.by Hyman A. Carrel.S.M

Predicting Avian Influenza Co-Infection with H5N1 and H9N2 in Northern Egypt.

Human outbreaks with avian influenza have been, so far, constrained by poor viral adaptation to non-avian hosts. This could be overcome via co-infection, whereby two strains share genetic material, allowing new hybrid strains to emerge. Identifying areas where co-infection is most likely can help target spaces for increased surveillance. Ecological niche modeling using remotely-sensed data can be used for this purpose. H5N1 and H9N2 influenza subtypes are endemic in Egyptian poultry. From 2006 to 2015, over 20,000 poultry and wild birds were tested at farms and live bird markets. Using ecological niche modeling we identified environmental, behavioral, and population characteristics of H5N1 and H9N2 niches within Egypt. Niches differed markedly by subtype. The subtype niches were combined to model co-infection potential with known occurrences used for validation. The distance to live bird markets was a strong predictor of co-infection. Using only single-subtype influenza outbreaks and publicly available ecological data, we identified areas of co-infection potential with high accuracy (area under the receiver operating characteristic (ROC) curve (AUC) 0.991)

Successful heart transplantation in a patient with Ivemark syndrome combined with situs inversus, single atrium and ventricle after total cavo-pulmonary connection

Heart transplantation represents a valuable therapeutical option for patients with congenital heart disease and end-stage heart failure. We report the case of a young adult patient with a situs inversus and additional complex congenital malformations of the heart who underwent several prior palliative interventions, a biventricular repair being impossible. Orthotopic cardiac transplantation with several technical modifications was performed successfully at the age of 19 year

Relationships between flood control and cholera in Matlab, Bangladesh

Implementation of flood control strategies has been empirically associated with rises in disease rates in the developing world. This research examines the impact of flood protection measures on cholera incidence among a rural Bangladeshi population. Using longitudinal health and demographic data collected over 21 years, analysis of clustering patterns and statistical relationships between cholera incidence and environmental factors was conducted for timeframes prior to and following the introduction of flood control in Matlab, Bangladesh. Results indicate that alteration of normal flooding patterns both temporally and spatially shifted cholera occurrence within the study area, and that these shifts demonstrate further differentiation when information on cholera strain is included in the analysis. These outcomes suggest that introducing flood protection to rural Bangladesh will have significant but complex effects on cholera incidence patterns

Space-time differentiation of drivers of and barriers to H5N1 avian influenza evolution in Vietnam

The emergence and re-emergence of human pathogens resistant to traditional medical treatment will present a challenge to the international public health community in the coming decades. Geography is uniquely positioned to examine the progressive evolution of pathogens across space and through time, and to link molecular change to interactions between population and environmental drivers. The widespread outbreak of H5N1 avian influenza across Asia in 2003, and its continued circulation within both poultry and human populations, presents an opportunity for the integration of traditional disease ecology with the emergent field of landscape genetics. Combining spatial statistical methods with genetic analytic techniques, geographic space is used to explore genetic evolution of H5N1 highly pathogenic avian influenza viruses (HPAIV) at the sub-national scale in Vietnam. This dissertation investigates the following topics: differences in genetic characteristics by species of isolation, location and timing of barriers to gene flow, and population-environment characteristics associated with increased viral evolution in Vietnam from 2003 to 2007. A variety of methods are used, including cluster analysis, multidimensional scaling, analysis of variance, and linear regression. Results indicate that genetic differentiation of these viruses varies significantly according to both their host species and the isolation time, but has a complex relationship with the geographic location of virus isolation. The effect of geographic space, and underlying landscape differentiation, does not appear to create boundaries to gene exchange across Vietnam. Taking these indicators of the influence of species, temporal characteristics and geographic space into account, the drivers of molecular evolution of H5N1 HPAIV in Vietnam are as predicted by a disease ecology framework, a combination of both population and environmental characteristics. These findings indicate that there are significant spatial and temporal effects on the evolution of H5N1 HPAIVs, and that local-level conditions can affect viral genetic evolution. Given that areas of rapid genetic evolution are more likely to produce a highly pathogenic virus capable of sustained human-to-human transmission, further exploration of spatial variation in molecular change is needed

360-degree Video Stitching for Dual-fisheye Lens Cameras Based On Rigid Moving Least Squares

Dual-fisheye lens cameras are becoming popular for 360-degree video capture, especially for User-generated content (UGC), since they are affordable and portable. Images generated by the dual-fisheye cameras have limited overlap and hence require non-conventional stitching techniques to produce high-quality 360x180-degree panoramas. This paper introduces a novel method to align these images using interpolation grids based on rigid moving least squares. Furthermore, jitter is the critical issue arising when one applies the image-based stitching algorithms to video. It stems from the unconstrained movement of stitching boundary from one frame to another. Therefore, we also propose a new algorithm to maintain the temporal coherence of stitching boundary to provide jitter-free 360-degree videos. Results show that the method proposed in this paper can produce higher quality stitched images and videos than prior work.Comment: Preprint versio

Relevamiento y sistematización de instrumentos de promoción de la investigación y desarrollo de las universidades de la Asociación de Universidad del Grupo Montevideo (AUGM)

El trabajo presenta resultados de un relevamiento realizado con el fin de sistematizar las principales características de los instrumentos de promoción de la I+D que se implementan en el núcleo de Universidad de la AUGM. Tal caracterización persigue un doble objetivo, por un lado conocer la diversidad de modalidades de promoción de la I+D que se da entre las universidades, y por el otro establecer el origen de los fondos que se canalizan en los diversos instrumentos. Con el primero de los objetivos se busca conocer la heterogeneidad de instrumentos que existen entre las Universidades del grupo, teniendo en cuenta la diversidad de los objetivos que los mismos persiguen, su modalidad de implementación y los mecanismos de evaluación previstos. Con el segundo de los objetivos, se pretende establecer las distintas fuentes de financiamientos que utilizan las Universidades para la promoción de la I+D. Para ello, el trabajo se divide en tres secciones y unas breves conclusiones. En la primera sección se realiza un breve presentación de la AUGM y de los objetivos del proyecto en el cual se realizó el relevamiento. En la segunda sección se analizan las principales características e los instrumentos, teniendo en cuenta los objetivos, la modalidad de implementación y los mecanismos de evaluación, en tanto que en la tercera sección se analizan las distintas fuentes de financiamiento, prestando especial atención a si los fondos provienen de la propia universidad, o si por el contrario, las fuentes de financiamiento son exógenas, en cuyo caso se establece el origen (sector gobierno, privado, etc.). Al final, unas breves conclusiones destacan los principales puntos del análisis. Todos los datos presentados son el resultado de un trabajo de campo (encuestas y entrevistas) aplicadas a las áreas de gestión de I+D de Universidades de AUGM, actividades que se enmarcan en un Proyecto de Promoción de la Universidad Argentina (PPUA).Fil: Comba, Daniel A.. Universidad Nacional del LitoralFil: Carrel, Lucila. Universidad Nacional del LitoralFil: Barros de Barros, Fabiana. Universidad de Melbourne (Australia)Fil: Hynes, Erica. Consejo Nacional de Investigaciones Científicas y Técnica