15 research outputs found
The genetic epidemiology of joint shape and the development of osteoarthritis
Congruent, low-friction relative movement between the articulating elements of a synovial joint is an essential pre-requisite for sustained, efficient, function. Where disorders of joint formation or maintenance exist, mechanical overloading and osteoarthritis (OA) follow. The heritable component of OA accounts for ~ 50% of susceptible risk. Although almost 100 genetic risk loci for OA have now been identified, and the epidemiological relationship between joint development, joint shape and osteoarthritis is well established, we still have only a limited understanding of the contribution that genetic variation makes to joint shape and how this modulates OA risk. In this article, a brief overview of synovial joint development and its genetic regulation is followed by a review of current knowledge on the genetic epidemiology of established joint shape disorders and common shape variation. A summary of current genetic epidemiology of OA is also given, together with current evidence on the genetic overlap between shape variation and OA. Finally, the established genetic risk loci for both joint shape and osteoarthritis are discussed
Ecos de la academia: Revista de la Facultad de Educación, Ciencia y Tecnología - FECYT Nro 6
Ecos de la academia, Revista de la Facultad de Educación Ciencia y Tecnología es una publicación científica de la Universidad Técnica del Norte, con revisión por pares a doble ciego que publica artículos en idioma español, quichua, portugués e inglés. Se edita con una frecuencia semestral con dos números por año.En ella se divulgan trabajos originales e inéditos generados por los investigadores, docentes y estudiantes de la FECYT, y contribuciones de profesionales de instituciones docentes e investigativas dentro y fuera del país, con calidad, originalidad y relevancia en las áreas de ciencias sociales y tecnología aplicada.Modelos multidimensionales del bienestar en contextos de enseñanza- aprendizaje: una revisión sistemática.
Nuevas tendencias para el área académica de la Publicidad en la zona 1 del Ecuador.
Propuesta de un curso de escritura académica bajo la base de modelos experienciales.
Aproximación al estudio de las emociones.
Seguimiento a egresados y graduados para actualizar el perfil de egreso y profesional.
Impacto de la Gerencia de Calidad en el clima organizacional en Educación Básica.
Comunicación efectiva del gerente educativo orientada al manejo de conflictos en el personal docente.
Meritocracia: Democratización o exclusión en el acceso a la educación superior en Ecuador.
Asertividad y desempeño académico en estudiantes universitarios.
La creatividad en la formación profesional.
Aspectos metodológicos en el proceso de enseñanza- aprendizaje de la gimnasia en estudiantes
de Educación Física.
English Language Learning Interaction through Web 2.0 Technologies.
La sistematización de la práctica educativa y su relación con la metodología de la investigación.
El ozono y la oxigenación hiperbárica: una vía para mejorar la recuperación en lesiones deportivas.
La labor tutorial: Independencia del aprendizaje en el contexto universitario.
Motivación hacia la profesión docente en la Enseñanza Secundaria.
El uso académico de Facebook y WhatsApp en estudiantes universitarios...
La educación superior en Ecuador: situación actual y factores de mejora de la calidad.
El Proyecto de Investigación “Imbabura Étnica”
Caracterización Textural Y Química De Catalizadores TI-SIO2 Cristalinos Usados En La Epoxidación De Ésteres Grasos
Discrete TiIV centers dispersed in a SiO2 matrix acts as strong electron acceptors,
therefore, they are useful in activating molecules or moieties which are electron-rich. The amount,
dispersion, accessibility and coordination of these centers determine their chemical efficiency. Several
Ti-MCM-41 materials where characterized using DRX, FT-IR, UV-Vis and nitrogen adsorption to
evaluate the dispersion, coordination and accessibility of Ti centers as well as the crystallinity, porosity
and surface area of the SiO2 matrix. This study allows a correlation between the chemical environment
of titanium, textural properties of the catalyst and its performance in the activation of O-O bonds
present in peroxides, used for the epoxidation of plant oils. Results suggest that the presence of
crystalline pores, in the epoxidation of oleic acid methylester with TBHP catalyzed by Ti-MCM-41, is
not necessary, because the reaction occurs in large extension on the external surface area. The
important issue is to have the titanium centers finely dispersed on a relatively high surface area.
Temperature should be below 70°C to minimize the ketone formation.Centros discretos de TiIV dispersos en una matriz de SiO2 actúan como fuertes aceptores
de electrones por lo cual son útiles para la activación de moléculas o funciones químicas densas en
electrones. La cantidad de estos centros, su dispersión, accesibilidad y coordinación, determinan su
eficiencia química; para determinar estas propiedades, varios materiales Ti-MCM-41 se caracterizaron
mediante DRX, FTIR, UV-Vis e isotermas de adsorción de N2; también se determinaron la
cristalinidad, porosidad y superficie específica de la matriz SiO2 permitiendo correlacionar el ambiente
fisicoquímico del titanio y las propiedades texturales del catalizador, con su efectividad en la
activación de enlaces O-O presentes en moléculas tipo peróxidos, usados en la epoxidación de aceites
vegetales. Los resultados sugieren que la presencia de poros cristalinos, en la epoxidación del
metiléster del ácido oleico con TBHP y catalizada con Ti-MCM-41, no es necesaria, puesto que la
reacción ocurre principalmente en el área externa a los poros. Lo realmente importante es tener centros
de Ti finamente dispersos sobre una área superficial alta y accesible. Por otro lado, la temperatura de
reacción deber estar por debajo de 70°C para minimizar la formación de subproductos (cetona)
Evolutionary Dynamics of GII.4 Noroviruses over a 34-Year Period▿ †
Noroviruses are a major cause of epidemic gastroenteritis in children and adults, and GII.4 has been the predominant genotype since its first documented occurrence in 1987. This study examined the evolutionary dynamics of GII.4 noroviruses over more than three decades to investigate possible mechanisms by which these viruses have emerged to become predominant. Stool samples (n = 5,424) from children hospitalized at the Children's Hospital in Washington, DC, between 1974 and 1991 were screened for the presence of noroviruses by a custom multiplex real-time reverse transcription-PCR. The complete genome sequences of five GII.4 noroviruses (three of which predate 1987 by more than a decade) in this archival collection were determined and compared to the sequences of contemporary strains. Evolutionary analysis determined that the GII.4 VP1 capsid gene evolved at a rate of 4.3 × 10−3 nucleotide substitutions/site/year. Only six sites in the VP1 capsid protein were found to evolve under positive selection, most of them located in the shell domain. No unique mutations were observed in or around the two histoblood group antigen (HBGA) binding sites in the P region, indicating that this site has been conserved since the 1970s. The VP1 proteins from the 1974 to 1977 noroviruses contained a unique sequence of four consecutive amino acids in the P2 region, which formed an exposed protrusion on the modeled capsid structure. This protrusion and other observed sequence variations did not affect the HBGA binding profiles of recombinant virus-like particles derived from representative 1974 and 1977 noroviruses compared with more recent noroviruses. Our analysis of archival GII.4 norovirus strains suggests that this genotype has been circulating for more than three decades and provides new ancestral strain sequences for the analysis of GII.4 evolution
Methanol to Gasoline-Range Hydrocarbons: Influence of Nanocrystal Size and Mesoporosity on Catalytic Performance and Product Distribution of ZSM-5
Improvement of synthesis methods for ZSM-5 zeolite, as a heteregeneous catalyst, is essential for a wide variety of different reactions in the chemical industry. Decreasing zeolite crystal size and introducing mesoporosity into the zeolite structure can improve its performance in catalytic reaction through decreasing the micropore diffusion path-length and increasing the external surface area. In this study, three different ZSM-5 zeolites (Nano-ZSM-5, Meso-ZSM-5, and Con-ZSM-5) were prepared by a single-templating procedure, and the reaction of methanol to gasoline-range hydrocarbons was evaluated over synthesized ZSM-5 crystals in a fixed-bed continuous flow reactor. Good correlation was observed between catalytic performance, product distribution, mesoporosity, and crystal size of ZSM-5 zeolites. Both nanocrystal and mesoporous ZSM-5 zeolites showed long-term catalytic stability compared with the conventional one. In contrast to conventional ZSM-5 catalyst, the nanocrystal and mesoporous ZSM-5 catalysts showed high selectivities for light olefins and alkyl aromatics, respectively, in the conversion of methanol to gasoline. These results clearly indicate that both crystal size and mesoporosity significantly influence the ZSM-5 lifetime and product distribution