External fixator configurations in tibia fractures: 1D optimization and 3D analysis comparison

The use of external fixation devices in orthopedic surgery is very common in open tibial fractures. A properly applied fixator may improve the healing process while one improperly applied might delay the healing process. The several external fixator systems used in clinical today, can be categorized into uniplanar–unilateral, uniplanar–bilateral, biplanar and multiplanar. The stability on the fracture focus and, therefore, the fracture healing process, is related with the type of external fixator configuration that is selected. The aim of this study is to discuss the principles for the successful application of unilateral–uniplanar external fixation, the assembly of its components, for the case of a transverse fractures using computational models. In this context, the fixation stiffness characteristics are evaluated using a simplified 1D finite element model for the tibia and external fixator. The beams are modeled with realistic cross-sectional geometry and material properties instead of a simplified model. The VABS (the Variational Asymptotic Beam Section analysis) methodology is used to compute the cross-sectional model for the generalized Timoshenko model, which was embedded in the finite element solver FEAP. The use of Timoshenko beam theory allows accounting for several kinds of loads, including torsion moments. Optimal design is performed with respect to the assembly of fixator components using a genetic algorithm. The optimization procedure is based on the evaluation of an objective function, which is dependent on the displacement at the fracture focus. The initial and optimal results are compared by performing a 3D analysis, for which different three-dimensional finite element models are created. The geometrical model of a tibia is created on the basis of data acquired by CAT scan, made for a healthy tibia of a 22 year old male. The 3D comparison of the 1D optimal results show a clear improvement on the objective function for the several load cases and, therefore, it is shown that appropriate selection of the external fixator geometrical features can lead to an improvement on the stability of the external fixator. The results obtained show that the optimal position of the side beam and the first pin should be as close as possible to the bone interface and as close as possible to the fracture focus, respectively. Concerning the second pin, it should be placed away from the first pin in case of flexion loads, to axial and torsion loads the second pin should be placed near the first pin

Fresh-cut melon quality during storage: an NMR study of water transverse relaxation time

Molecular mobility is a fundamental parameter which reflects the dynamic properties of food components and contributes to food degradation reactions comprehension. Fresh-cut fruits have become an important food market segment. However, processing of fruits promotes faster its physiological deterioration, biochemical changes and microbial degradation. The purpose of this work was to use NMR methodology as a tool to evaluate fresh-cut fruit quality, during storage at refrigerated conditions. The fresh-cut melon transverse relaxation time (T2) was measured for a period of 7 days of storage at 5 °C. The relationship between the obtained values, microstructure and quality parameters was investigated. In general, results show the existence of one class of water fluidity in the system, the one present in cells after processing. T2, a measure of this fluidity, is affected by the processing and storage time. Also, it is possible to find a close relationships between T2 and quality parameters of total colour difference (TCD), firmness and aw. As T2 increases TCD also increases, while firmness and aw decrease. These results highlight the usefulness of NMR methodology application in food science.Author Joana F. Fundo acknowledges Fundacao para a Ciencia e a Tecnologia (grant SFRH/BD/62176/2009). The authors acknowledge the Portuguese NMR Network and Strategic Project PEst-C/CTM/LA0025/2013-14. This work was supported by National Funds from FCT through project PEst-OE/EQB/LA0016/201

Synthesis and characterization of the thermal and the solvatochromic properties of heterocyclic azo dyes derived from 5-N,N-dialkylamino-2,2´-bithiophene couplers

A series of heterocyclic azo dyes was synthesized by diazotation of several substituted anilines and coupling with 5-N,N-dialkylamino-2,2´-bithiophenes to give 4-phenylazo-5-N,N-dialkylamino-2,2´-bithiophenes 4-7. This reaction contrasts with the behavior of 5-alkoxy-2,2´-bithiophenes towards aryldiazonium salts which gave 5-phenylazo-5-alkoxy-2,2´-bithiophenes. The thermal stability of the derivatives was evaluated using thermogravimetric analysis. The solvatochromic behaviour of the novel bithiophene azo dyes was investigated in several solvents of different polarity. The experimental results indicate that, the heterocyclic azo dyes 4-7 could be used as thermally stable solvatochromic probes.Fundação para a Ciência e a Tecnologia (FCT

Kinetochore alignment within the metaphase plate is regulated by centromere stiffness and microtubule depolymerases

During mitosis in most eukaryotic cells, chromosomes align and form a metaphase plate halfway between the spindle poles, about which they exhibit oscillatory movement. These movements are accompanied by changes in the distance between sister kinetochores, commonly referred to as breathing. We developed a live cell imaging assay combined with computational image analysis to quantify the properties and dynamics of sister kinetochores in three dimensions. We show that baseline oscillation and breathing speeds in late prometaphase and metaphase are set by microtubule depolymerases, whereas oscillation and breathing periods depend on the stiffness of the mechanical linkage between sisters. Metaphase plates become thinner as cells progress toward anaphase as a result of reduced oscillation speed at a relatively constant oscillation period. The progressive slowdown of oscillation speed and its coupling to plate thickness depend nonlinearly on the stiffness of the mechanical linkage between sisters. We propose that metaphase plate formation and thinning require tight control of the state of the mechanical linkage between sisters mediated by centromeric chromatin and cohesion

Mineral content and volatile profiling of Prunus avium L. (sweet cherry) y-Products from Fundão Region (Portugal)

Large amounts of Prunus avium L. by-products result from sweet cherry production and processing. This work aimed to evaluate the mineral content and volatile profiling of the cherry stems, leaves, and flowers of the Saco cultivar collected from the Fundão region (Portugal). A total of 18 min erals were determined by ICP-MS, namely 8 essential and 10 non-essential elements. Phosphorus (P) was the most abundant mineral, while lithium (Li) was detected in trace amounts. Three different preparations were used in this work to determine volatiles: hydroethanolic extracts, crude extracts, and aqueous infusions. A total of 117 volatile compounds were identified using HS-SPME/GC MS, distributed among different chemical classes: 31 aldehydes, 14 alcohols, 16 ketones, 30 esters, 4 acids, 4 monoterpenes, 3 norisoprenoids, 4 hydrocarbons, 7 heterocyclics, 1 lactone, 1 phenol, and 2 phenylpropenes. Benzaldehyde, 4-methyl-benzaldehyde, hexanal, lilac aldehyde, and 6-methyl 5-hepten-2-one were the major volatile compounds. Differences in the types of volatiles and their respective amounts in the different extracts were found. This is the first study that describes the mineral and volatile composition of Portuguese sweet cherry by-products, demonstrating that they could have great potential as nutraceutical ingredients and natural flavoring agents to be used in the pharmaceutical, cosmetic, and food industries.info:eu-repo/semantics/publishedVersio

Experiencias en la programación de computadoras a partir de competencias

La programación de computadoras ha dejado de considerarse una actividad individual para pasar a convertirse en trabajo colaborativo de tal manera que los programadores trabajan en espacios virtuales construyendo partes de aplicaciones que luego resultan en implementaciones globales. La enseñanza de las diferentes metodologías de la programación de computadoras esta obligada a evolucionar hacia el aprendizaje colaborativo para ir incorporando en el estudiante, ese contexto de trabajo. Nuestro proyecto esta enfocado en realizar propuestas novedosas que modifiquen los hábitos del aprendizaje de la programación y el desarrollo de aplicaciones, aumentando el grado de interacción de los estudiantes entre si, así como el uso de la tecnología, para lograr como resultado aumentar la motivación y la construcción del conocimiento. En los dos últimos años hemos trabajado en adoptar diferentes enfoques que prioricen las practicas de aprendizaje colaborativo, y aprendizaje basado en proyectos competitivo. En la búsqueda de estrategias para la enseñanza de programación surgen los torneos utilizando herramientas tecnológicas para su evaluación y rankeado.Eje: Tecnología Informática Aplicada en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Experiencias en la programación de computadoras a partir de competencias

La programación de computadoras ha dejado de considerarse una actividad individual para pasar a convertirse en trabajo colaborativo de tal manera que los programadores trabajan en espacios virtuales construyendo partes de aplicaciones que luego resultan en implementaciones globales. La enseñanza de las diferentes metodologías de la programación de computadoras esta obligada a evolucionar hacia el aprendizaje colaborativo para ir incorporando en el estudiante, ese contexto de trabajo. Nuestro proyecto esta enfocado en realizar propuestas novedosas que modifiquen los hábitos del aprendizaje de la programación y el desarrollo de aplicaciones, aumentando el grado de interacción de los estudiantes entre si, así como el uso de la tecnología, para lograr como resultado aumentar la motivación y la construcción del conocimiento. En los dos últimos años hemos trabajado en adoptar diferentes enfoques que prioricen las practicas de aprendizaje colaborativo, y aprendizaje basado en proyectos competitivo. En la búsqueda de estrategias para la enseñanza de programación surgen los torneos utilizando herramientas tecnológicas para su evaluación y rankeado.Eje: Tecnología Informática Aplicada en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Experiencias en la programación de computadoras a partir de competencias

La programación de computadoras ha dejado de considerarse una actividad individual para pasar a convertirse en trabajo colaborativo de tal manera que los programadores trabajan en espacios virtuales construyendo partes de aplicaciones que luego resultan en implementaciones globales. La enseñanza de las diferentes metodologías de la programación de computadoras esta obligada a evolucionar hacia el aprendizaje colaborativo para ir incorporando en el estudiante, ese contexto de trabajo. Nuestro proyecto esta enfocado en realizar propuestas novedosas que modifiquen los hábitos del aprendizaje de la programación y el desarrollo de aplicaciones, aumentando el grado de interacción de los estudiantes entre si, así como el uso de la tecnología, para lograr como resultado aumentar la motivación y la construcción del conocimiento. En los dos últimos años hemos trabajado en adoptar diferentes enfoques que prioricen las practicas de aprendizaje colaborativo, y aprendizaje basado en proyectos competitivo. En la búsqueda de estrategias para la enseñanza de programación surgen los torneos utilizando herramientas tecnológicas para su evaluación y rankeado.Eje: Tecnología Informática Aplicada en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Dry Markets and Superreplication Bounds of American Derivatives

This paper studies the impact of dry markets for underlying assets on the pricing of American derivatives, using a discrete time framework. Dry markets are characterized by the possibility of non-existence of trading at certain dates. Such non-existence may be deterministic or probabilistic. Using superreplicating strategies, we derive expectation representations for the range of arbitrage-free values of the dervatives. In the probabilistic case, if we consider an enlarged filtration induced by the price process and the market existence process, ordinary stopping times are required. If not, randomized stopping times are required. Several comparisons of the ranges obtained with the two market restrictions are performed. Finally, we conclude that arbitrage arguments are not enough to define the optimal exercise policy.N/