Aportación de la densitometría ósea en las artroplastias de rodilla

El presente trabajo consiste en una revisión clínica y radiológica de 84 artroplastias modulares de rodilla de las cuales, en 19 se ha estudiado la masa ósea periprotésica (7 cementadas y 12 sin cementar) antes, al mes y a los seis meses de la intervención mediante un densitómetro de doble fotón. Aparte, se ha probado la correlación directa entre la indicación peroperatoria de no cementar y una mayor masa ósea en todas las zonas periprotésicas; por otro lado, se ha observado una diferente distribución de la densidad mineral ósea en la tibia tras la intervención, según se haya utilizado o no cemento. Estos hallazgos confirman el estudio densitométrico previo a la intervención como un método complementario útil en la indicación de la cementación de la artroplastia total de rodilla.A clinical and radiological revision of 84 modular knee arthroplasties is presented. Periprosthesis bone mineral content was studied in 19 prostheses (7 cemented and 12 uncemented) before, surgery one and 6 months after the intervention using a densitometer of double energy. A direct correlation between the implantation of a non-cemented prosthesis and the growth of the bone mass in all the periprosthesis areas was found, existing a different distribution of the mineral bone density of the tibia after the intervention depending on the use of cement. These findings show that the densitometric study previous to an intervention as a useful complementary method in the indication of cemented total knee arthroplasty

Chaotic scattering with direct processes: A generalization of Poisson's kernel for non-unitary scattering matrices

The problem of chaotic scattering in presence of direct processes or prompt responses is mapped via a transformation to the case of scattering in absence of such processes for non-unitary scattering matrices, \tilde S. In the absence of prompt responses, \tilde S is uniformly distributed according to its invariant measure in the space of \tilde S matrices with zero average, < \tilde S > =0. In the presence of direct processes, the distribution of \tilde S is non-uniform and it is characterized by the average (\neq 0). In contrast to the case of unitary matrices S, where the invariant measures of S for chaotic scattering with and without direct processes are related through the well known Poisson kernel, here we show that for non-unitary scattering matrices the invariant measures are related by the Poisson kernel squared. Our results are relevant to situations where flux conservation is not satisfied. For example, transport experiments in chaotic systems, where gains or losses are present, like microwave chaotic cavities or graphs, and acoustic or elastic resonators.Comment: Added two appendices and references. Corrected typo

Dripping Faucet Dynamics Clarified by an Improved Mass-Spring Model

An improved mass-spring model for a dripping faucet is presented. The model is constructed based on the numerical results which we recently obtained from fluid dynamical calculations. Both the fluid dynamical calculations and the present mass-spring model exhibit a variety of complex behavior including transition to chaos in good agreement with experiments. Further, the mass-spring model reveals fundamental dynamics inherent in the dripping faucet system.Comment: 17 pages, 17 figure

Estudio comparativo de la fijación con o sin cemento en Prótesis Total de Rodilla

Revisamos retrospectivamente una serie de 86 pacientes portadores de 110 prótesis totales modulares de rodilla colocadas como tratamiento de la gonartrosis. Se analizan los resultados obtenidos en los pacientes a los que se le realizó una fijación híbrida cementada (componente femoral no cementado y componente tibial y patelar cementado) respecto a los que se le realizó una prótesis de anclaje biológico sin ningún tipo de cementación. El análisis de la función clínica, movilidad de la rodilla, estudio radiológico y complicaciones de ambas series no demuestran diferencias significativas entre ambos grupos con un periodo de seguimiento de 45 meses (r=12-60).We have retrospectively review 86 patients with 110 total knee arthroplasty for the treatment of osteoarthrosis. We have analyzed the results obtained in a group of patients with partial fixation with cement and another group fixated without any cement. Clinical and radiological results and complications in both groups were similar without significant differences with an average follow-up of 45 months (12-60)

Experiencia a medio plazo con prótesis total de rodilla semiconstreñida

Revisamos 25 prótesis totales de rodilla semiconstreñidas tipo Endo-Model Waldemar- Link implantadas en 23 pacientes con una edad media de 69,5 años y un seguimiento medio de 32 meses. Para la evaluación de los resultados clínicos hemos utilizado el protocolo de la Academia Americana en el que se incluyen los parámetros de: dolor, capacidad para la marcha, facilidad para subir y bajar escaleras, necesidad o no de bastones y flexoextensión de la articulación, tanto antes como después de la intervención. Asimismo hemos realizado un estudio radiológico de las prótesis en el que se ha valorado el centraje de los componentes protésicos en dos planos AP y L y las imágenes líticas periprotésicas. Los resultados obtenidos han sido satisfactorios observando en la totalidad de los pacientes una disminución del dolor y un aumento de su capacidad funcional. En ningún caso se han observado infecciones profundas de la prótesis. Se ha comprobado un aumento en el arco de flexión en las prótesis en que la punta del vástago femoral estaba desviada hacia la cortical anterior, sin que esto se acompañase de un déficit en la extensión.We have reviewed 25 total knee prosthesis (Endo-Model type, Waldemar-Link) performed in 23 patients with an age average of 69,5 years-old and a average follow-up of 32 months. The clinical assessment applied was the AAOS protocol including the parameters of: pain, ability to go up and down the stairs, to need of sticks, flexion and extension of the joint, before and after the operation. In the radiological study we have evaluated the correct alignment of the components in two planes A-P and L, and the periprosthetic lucencies. The results obtained have been satisfying in all the patients with a diminution of the pain and better function of the joint. No deep infection was observed and the flexion was better in prosthesis with anterior deviation of the femoral rod in the lateral plane

Self-sufficient asymmetric reduction of β-ketoesters catalysed by a novel and robust thermophilic alcohol dehydrogenase co-immobilised with NADH

β-Hydroxyesters are essential building blocks utilised by the pharmaceutical and food industries in the synthesis of functional products. Beyond the conventional production methods based on chemical catalysis or whole-cell synthesis, the asymmetric reduction of β-ketoesters with cell-free enzymes is gaining relevance. To this end, a novel thermophilic (S)-3-hydroxybutyryl-CoA dehydrogenase from Thermus thermophilus HB27 (Tt27-HBDH) has been expressed, purified and biochemically characterised, determining its substrate specificity towards β-ketoesters and its dependence on NADH as a cofactor. The immobilization of Tt27-HBDH on agarose macroporous beads and its subsequent coating with polyethyleneimine has been found the best strategy to increase the stability and workability of the heterogeneous biocatalyst. Furthermore, we have embedded NADH in the cationic layer attached to the porous surface of the carrier. Since Tt27-HBDH catalyses cofactor recycling through 2-propanol oxidation, we achieve a self-sufficient heterogeneous biocatalyst where NADH is available for the immobilised enzymes but its lixiviation to the reaction bulk is avoided. Taking advantage of the autofluorescence of NADH, we demonstrate the activity of the enzyme towards the immobilised cofactor through single-particle analysis. Finally, we tested the operational stability in the asymmetric reduction of β-ketoesters in batch, succeeding in the reuse of both the enzyme and the co-immobilised cofactor up to 10 reaction cycles

On the Derivational Entropy of Left-to-Right Probabilistic Finite-State Automata and Hidden Markov Models

[EN] Probabilistic finite-state automata are a formalism that is widely used in many problems of automatic speech recognition and natural language processing. Probabilistic finite-state automata are closely related to other finite-state models as weighted finite-state automata, word lattices, and hidden Markov models. Therefore, they share many similar properties and problems. Entropy measures of finite-state models have been investigated in the past in order to study the information capacity of these models. The derivational entropy quantifies the uncertainty that the model has about the probability distribution it represents. The derivational entropy in a finite-state automaton is computed from the probability that is accumulated in all of its individual state sequences. The computation of the entropy from a weighted finite-state automaton requires a normalized model. This article studies an efficient computation of the derivational entropy of left-to-right probabilistic finite-state automata, and it introduces an efficient algorithm for normalizing weighted finite-state automata. The efficient computation of the derivational entropy is also extended to continuous hidden Markov models.This work has been partially supported through the European Union's H2020 grant READ (Recognition and Enrichment of Archival Documents) (Ref: 674943) and the MINECO/FEDER-UE project TIN2015-70924-C2-1-R. The second author was supported by the "Division de Estudios de Posgrado e Investigacion" of Instituto Tecnologico de Leon.Sánchez Peiró, JA.; Rocha, MA.; Romero, V.; Villegas, M. (2018). On the Derivational Entropy of Left-to-Right Probabilistic Finite-State Automata and Hidden Markov Models. Computational Linguistics. 44(1):17-37. https://doi.org/10.1162/COLI_a_00306S1737441Abney, S., McAllester, D., & Pereira, F. (1999). 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Estudio de la marcha en pacientes tratados ortopédicamente de fractura unilateral del calcáneo

Veinticinco pacientes afectos de fractura unilateral desplazada articular de calcá- neo fueron tratados mediante inmovilización con yeso, siendo los resultados a los 6 años (rango: 3-10), excelentes en 5 pacientes, buenos en 4, regulares en 7 y malos en 9. De este grupo se excluyeron los afectos de patología local o general asociada, siendo útiles para el estudio de la marcha 12 pacientes a los que se les hizo deambular sobre plataformas dinamométricas para registrar la fuerza de reacción al suelo, demostrando una disminución de la fuerza vertical de apoyo y despegue (F1 y F3) y un aumento estadísticamente significativo del tiempo de apoyo total durante la marcha. Abogamos por la restitución anatómica del calcáneo como medio para mejorar la capacidad funcional del paciente.Twenty-five patients with unilateral displaced joint calcaneus fracture were treated by cast being the results after 6 years (range: 3-10), excellent in 5 patients, good in 4 patients, poor in 7 and bad in 9. We excluded for the study the patients with associated local or general pathology being useful for our study 12 patients. These patients walked on a dynamometric platform in order to analyse floor reaction forces, proving a diminuí ion of vertical support and takeoff forces (Fl and F2), and statistically significant a increase of total support phase during gait