Development of a planar multi-body model of the human knee joint

The aim of this work is to develop a dynamic model for the biological human knee joint. The model is formulated in the framework of multibody systems methodologies, as a system of two bodies, the femur and the tibia. For the purpose of describing the formulation, the relative motion of the tibia with respect to the femur is considered. Due to their higher stiffness compared to that of the articular cartilages, the femur and tibia are considered as rigid bodies. The femur and tibia cartilages are considered to be deformable structures with specific material characteristics. The rotation and gliding motions of the tibia relative to the femur can not be modeled with any conventional kinematic joint, but rather in terms of the action of the knee ligaments and potential contact between the bones. Based on medical imaging techniques, the femur and tibia profiles in the sagittal plane are extracted and used to define the interface geometric conditions for contact. When a contact is detected, a continuous non-linear contact force law is applied which calculates the contact forces developed at the interface as a function of the relative indentation between the two bodies. The four basic cruciate and collateral ligaments present in the knee are also taken into account in the proposed knee joint model, which are modeled as non-linear elastic springs. The forces produced in the ligaments, together with the contact forces, are introduced into the system’s equations of motion as external forces. In addition, an external force is applied on the center of mass of the tibia, in order to actuate the system mimicking a normal gait motion. Finally, numerical results obtained from computational simulations are used to address the assumptions and procedures adopted in this study.Fundação para a Ciência e a Tecnologia (FCT

Modeling of the condyle elements within a biomechanical knee model

The development of a computational multibody knee model able to capture some of the fundamental properties of the human knee articulation is presented. This desideratum is reached by including the kinetics of the real knee articulation. The research question is whether an accurate modeling of the condyle contact in the knee will lead to reproduction of the complex combination of flexion/extension, abduction/adduction and tibial rotation ob-served in the real knee? The model is composed by two anatomic segments, the tibia and the femur, whose characteristics are functions of the geometric and anatomic properties of the real bones. The biomechanical model characterization is developed under the framework of multibody systems methodologies using Cartesian coordinates. The type of approach used in the proposed knee model is the joint surface contact conditions between ellipsoids, represent-ing the two femoral condyles, and points, representing the tibial plateau and the menisci. These elements are closely fitted to the actual knee geometry. This task is undertaken by con-sidering a parameter optimization process to replicate experimental data published in the lit-erature, namely that by Lafortune and his co-workers in 1992. Then, kinematic data in the form of flexion/extension patterns are imposed on the model corresponding to the stance phase of the human gait. From the results obtained, by performing several computational simulations, it can be observed that the knee model approximates the average secondary mo-tion patterns observed in the literature. Because the literature reports considerable inter-individual differences in the secondary motion patterns, the knee model presented here is also used to check whether it is possible to reproduce the observed differences with reasonable variations of bone shape parameters. This task is accomplished by a parameter study, in which the main variables that define the geometry of condyles are taken into account. It was observed that the data reveal a difference in secondary kinematics of the knee in flexion ver-sus extension. The likely explanation for this fact is the elastic component of the secondary motions created by the combination of joint forces and soft tissue deformations. The proposed knee model is, therefore, used to investigate whether this observed behavior can be explained by reasonable elastic deformations of the points representing the menisci in the model.Fundação para a Ciência e a Tecnologia (FCT) - PROPAFE – Design and Development of a Patello-Femoral Prosthesis (PTDC/EME-PME/67687/2006), DACHOR - Multibody Dynamics and Control of Hybrid Active Orthoses MIT-Pt/BSHHMS/0042/2008, BIOJOINTS - Development of advanced biological joint models for human locomotion biomechanics (PTDC/EME-PME/099764/2008)

VALUACIÓN DE UNA FINCA DE REGADÍO ENFOCADA AL CULTIVO HORTÍCOLA

Objective: To evaluate a horticultural irrigated farm located in Puebla, which is focused on cultivating: bean, lettuce, tomato, carrot and wheat. Design/methodology/approximation: Some of the agrarian valuation methods that best suit the case study were used, specifically the synthetic method by comparison of rates and the updated analytical method. Results: The results obtained from the applied methods allowed to get a final value of the farm object of study of $20,951,695.68 mexican pesos Limitations of the study/implications: This definitive result implies a value with the theoretical underpinnings required to represent the effective contribution of a valid and universal knowledge with professional and academic relevance; and which is limited for the analysis of assets with similar characteristics. Findings/conclusions: The utility of employing effective valuation methods applicable to agricultural lands when considering the importance of such activities for both the economy of Puebla and for the corresponding to the entire mexican territory.Objetivo: Valuar una finca de regadío hortícola ubicada en Puebla enfocada en cultivar: haba, lechuga, jitomate, zanahoria y trigo. Diseño/metodología/aproximación: Se utilizaron algunos de los métodos de valuación agraria que más se adecúan al caso de estudio, específicamente el método sintético por comparación de tasas y el método analítico actualizado. Resultados: Los resultados obtenidos a partir de los métodos empleados permitieron llegar un valor final de la finca objeto de estudio de$20,951,695.68 pesos mexicanos. Limitaciones del estudio/implicaciones: Dicho resultado definitivo implica un valor con los sustentos teóricos requeridos para representar la contribución efectiva de un conocimiento válido y universal con pertinencia profesional y académica; y el cual está limitado para el análisis de activos con características similares. Hallazgos/conclusiones: La utilidad de emplear métodos de valuación efectivos aplicables a terrenos agrícolas al considerar la importancia de dichas actividades tanto para la economía de Puebla como para la correspondiente a todo el territorio mexicano

Cluster Monte Carlo and dynamical scaling for long-range interactions

Many spin systems affected by critical slowing down can be efficiently simulated using cluster algorithms. Where such systems have long-range interactions, suitable formulations can additionally bring down the computational effort for each update from O($N^2$) to O($N\ln N$) or even O($N$), thus promising an even more dramatic computational speed-up. Here, we review the available algorithms and propose a new and particularly efficient single-cluster variant. The efficiency and dynamical scaling of the available algorithms are investigated for the Ising model with power-law decaying interactions.Comment: submitted to Eur. Phys. J Spec. Topic

Degradabilidade in situ de híbridos de milho e de capim-elefante colhidos em quatro estádios de maturidade

Dentre as forragens, a silagem de milho é amplamente utilizada pelos fazendeiros que visam explorar o máximo do potencial genético dos animais. No entanto, outros volumosos tropicais como o capim-elefante (Pennisetum purpureum) são mais produtivos e, portanto, mais baratos do que a silagem de milho. Nosso objetivo foi comparar a degradabilidade in situ do capim-elefante com a degradabilidade de híbridos de milho, colhidos em quatro estágios de maturidade. O experimento seguiu um delineamento de blocos ao acaso com sub-parcelas. Dois híbridos de milho: AG5011 e ZN8392 foram colhidos com 25, 30, 35 e 40% matéria seca (MS) na planta toda e separados na fração colmo + bainha + folhas e espigas. Capim elefante foi colhido 30, 40, 50 e 60 dias após o corte de nivelamento. As amostras secas e trituradas foram incubadas no rúmen por 0, 6, 12, 24, 48 e 72 h para cálculo da cinética da degradação ruminal da MS e da fibra em detergente neutro (FDN). O avanço da maturidade aumentou os teores de FDN e fibra em detergente ácido (FDA) do capim elefante e reduziu a degradabilidade da MS. Entretanto, a maturidade teve pouco efeito sobre os teores de fibra e a degradabilidade da MS da fração planta dos híbridos de milho. O capim elefante apresentou maior degradabilidade da FDN do que híbridos de milho, e não houve efeito da maturidade sobre a degradabilidade da FDN das duas espécies. A degradabilidade da fibra de capim-elefante não é pior do que a de híbridos de milho e, portanto a escolha da forragem deve ser feita com base em análises econômicas ao invés de assumir um menor potencial de produção em dietas a base de capim elefanteAmong tropical forages, corn silage is largely used by farmers trying to explore the maximum genetic potential from the animals. However, other tropical forages, such as elephant-grass (Pennisetum purpureum), are more productive and therefore cheaper to use than corn silage. Our objective was to compare the in situ degradability of elephant-grass with that from corn hybrids, all harvested at four stages of maturity. The experimental design followed a randomized block design with nested subplots. Two corn hybrids: AG5011, ZN8392 were harvested with 25, 30, 35, and 40% dry matter (DM) in the whole plant, and separated in stem + leaf sheath + leaf blade (stover), and cobs. Elephant-grass was harvested with 30, 40, 50 and 60 days after a leveling cut. Dried and ground samples were incubated in nylon bags inside the rumen for 0, 6, 12, 24, 48 and 72 h to estimate the kinetics of ruminal DM and neutral detergent fiber (NDF) degradation. The advance of maturity increased the NDF and acid detergent fiber (ADF) content in elephant-grass, and reduced its DM degradability. However, maturity had little or no effect on fiber content and DM degradability of corn stover. Elephant-grass had a higher NDF degradability than corn stover, and there was no effect of maturity on NDF degradability of either elephant-grass or corn stover. Fiber degradability of elephant-grass was not worse than that of corn stover, and therefore the choice of forage should be made on economical analysis rather than assuming an intrinsic low production potential for elephant-grass based diet

Valuación de una finca de regadío enfocada al cultivo hortícola

Objective: To evaluate a horticultural irrigated farm located in Puebla, which is focused on cultivating: bean, lettuce, tomato, carrot and wheat.Design/methodology/approximation: Some of the agrarian valuation methods that best suit the case study were used, specifically the synthetic method by comparison of rates and the updated analytical method.Results: The results obtained from the applied methods allowed to get a final value of the farm object of study of $ 20,951,695.68 mexican pesos.Limitations of the study/implications: This definitive result implies a value with the theoretical underpinnings required to represent the effective contribution of a valid and universal knowledge with professional and academic relevance; and which is limited for the analysis of assets with similar characteristics.Findings/conclusions: The utility of employing effective valuation methods applicable to agricultural lands when considering the importance of such activities for both the economy of Puebla and for the corresponding to the entire mexican territory

Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

Peer reviewe

Obtención de carbones activados a partir de residuos agroindustriales y su evaluación en la remoción de color y carga orgánica en lactosuero ácido

Activated Carbon is the term used to describe carbon-based materials containing a well-developed internal pore structure. They are materials having specific properties of interest, such as thermal stability, resistance to acid attack, hydrophobicity, relative low cost and especially a porous structure, a property that has led to an increase  in the number of research to production and application. They are very effective adsorbent materials due to their highly developed porous structure, large surface area (500-3000 m2.g-1), and chemical characteristics variables. They are very versatile material with many applications in various fields, mainly in the field of environment. Lignocellulosic wastes from farm products are currently used as precursors for the production of potentially useful products with higher added value, such as coals. Currently, agricultural and forestry residues found use as raw materials for other uses; nevertheless, there is a lot of waste produced each year and require disposal, leading to an environmental problem. One of the current ways to reduce waste generated by agribusiness is the recovery and use of renewable raw materials. Therefore, a viable option is to convert this waste into activated to be implemented and evaluated in various environmental pollution problems coals. Get activated from agroindustrial waste barley hulls, corn cobs and agaves sheets by physical activation methods, chemical and microwave induced adsorbent for their ability to reduce color and organic load remaining coals treatments electrofloculation acid whey, are the objectives of this work.Carbones activados son materiales que presentan propiedades específicas de interés, como estabilidad térmica, resistencia al ataque ácido, carácter hidrófobo, bajo costo relativo y especialmente una estructura porosa, propiedad que ha propiciado el aumento en el número de investigaciones destinadas a su producción y aplicación. Materiales adsorbentes muy efectivos por su estructura porosa altamente desarrollada, grandes áreas de superficie (500-3000 m2g-1), y características químicas variables. Son muy versátiles con numerosas aplicaciones en diversas áreas. Los residuos lignocelulósicos provenientes de productos del campo han sido utilizados actualmente como precursores para la obtención de productos potencialmente útiles y con mayor valor agregado, como es el caso de los carbones; a pesar de ello, hay una gran cantidad de residuos que se producen cada año y que requieren su eliminación, lo cual conduce a un problema ambiental. Una de las formas actuales para reducir residuos generados por la agroindustria es la valorización y uso de materias primas renovables. Por tal motivo, una opción viable es la conversión de este tipo de residuos en carbones activados para ser aplicados y evaluados en diversos problemas de contaminación ambiental. Obtener carbones activados a partir de residuos agroindustriales de cascarilla de cebada, olotes de maíz y hojas de agaves mediante métodos de activación física, química e inducida con microondas para evaluar su capacidad adsorbente en la reducción de color y carga orgánica remanentes de tratamientos de electrofloculación en lactosuero ácido, son los objetivos de este trabajo

Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

Peer reviewe