Tight coupling in thermal Brownian motors

We study analytically a thermal Brownian motor model and calculate exactly the Onsager coefficients. We show how the reciprocity relation holds and that the determinant of the Onsager matrix vanishes. Such condition implies that the device is built with tight coupling. This explains why Carnot's efficiency can be achieved in the limit of infinitely slow velocities. We also prove that the efficiency at maximum power has the maximum possible value, which corresponds to the Curzon-Alhborn bound. Finally, we discuss the model acting as a Brownian refrigerator

Epifisiolisis triplana del extremo distal de la tibia asociada a fractura diafisaria ipsilateral de tibia: Caso clínico

Presentamos un caso de epifisiolisis triplana del extreme distal de la tibia asociado a una fractura ipsilateral de tibia, en un niño de 14 años. La asociación de estas dos fracturas no ha sido descrita previamente, en la amplia revisión bibliográfica realizada por los autores. Proponemos que este tipo de lesión sea incluido como tipo IV en la clasificación de Dias y Tachdjian.We report a case of simultaneus triplane fracture of the distal tibial epiphysis and spiral fracture of the ipsilateral tibial-shaft fracture in a 13 year-old boy. The association of these two lesions has not previously been reported and can be considered as a new lesional type IV triplane fracture of the distal tibial epiphysis

Aspectos epidemiológicos del traumatismo múltiple en un hospital de referencia: experiencia de 1 año

Se ha realizado un estudio epidemiológico de los traumatismos múltiples (TM) atendidos en el Servicio de Traumatología del Hospital Clínico de Valencia en 1992. De los 285 casos ingresados en el centro, 180 tuvieron su ingreso final en el Servicio de Traumatología. Ciento treinta y tres casos fueron varones y 47 mujeres, con edad media de 33 años. Se analizaron las variables edad, sexo, mecanismo lesional, días de ingreso, tipos de lesión, asociación de lesiones y tratamiento realizado. Por edad, la mayor incidencia fue de los l1 a los 40 años. La causa principal fue el accidente de tráfico. El Injury Severity Score (ISS) medio para toda la serie fue de 12,5 (rango: 3-48). El 75% de los pacientes tenían lesiones musculoesqueléticas en forma aislada. Las lesiones asociadas fueron traumatismo craneoencefálico (76 casos), traumatismo torácico (7 casos), traumatismo abdominal (6 casos) y combinaciones de ellos (16 casos). Se contabilizaron 345 fracturas (1,9 por paciente). La mayor frecuencia se observó en la extremidad inferior (48%), siendo la tibia el hueso más frecuentemente afectado. En total de 166 fracturas fueron tratadas en forma ortopédica, mientras que en 183 de ellas se realizó tratamiento quirúrgico (1,1 intervenciones por paciente). La estancia media hospitalaria fue de 14 días, con un tiempo de hospitalización significativamente mayor en los pacientes con un ISS mayor de 9.The cases of multiple trauma admitted in the University Clinic Hospital of Valencia during 1992 were epidemiologically assessed. A group of 180 patients were finally admitted in the Trauma Unit from a total of 285 hospital admittances. There were 133 men and 47 women, with mean age of 33 years. Age, sex, etiology, period of hospital discharge, type of injury, associated lesions and treatment were recorded from clinical charts. The age group between 11 and 40 years was the most frequently affected. Traffic accident was the most important cause of injury. The mean Injury Severity Score (ISS) for the hole series was 12,4 (3-48). Isolated musculoskeletal injury was found in 75% of the cases. Associated lesions were head trauma (76 cases), thoracic trauma (seven cases) and abdominal trauma (six cases). More than two combinations were found in 16 cases. A total of 345 fractures were recorded (1.9 fractures per patient). The highest frequency was observed in the lower extremity (48%). The tibia was the most affected bone. Conservative treatment was applied in 166 cases, while 183 cases were treated surgically (1.1 surgeries per patient). The mean hospital discharge was 14 days. Patients with ISS > 9 showed a significant higher hospital stay as compared to those with ISS < 9

From subdiffusion to superdiffusion of particles on solid surfaces

We present a numerical and partially analytical study of classical particles obeying a Langevin equation that describes diffusion on a surface modeled by a two dimensional potential. The potential may be either periodic or random. Depending on the potential and the damping, we observe superdiffusion, large-step diffusion, diffusion, and subdiffusion. Superdiffusive behavior is associated with low damping and is in most cases transient, albeit often long. Subdiffusive behavior is associated with highly damped particles in random potentials. In some cases subdiffusive behavior persists over our entire simulation and may be characterized as metastable. In any case, we stress that this rich variety of behaviors emerges naturally from an ordinary Langevin equation for a system described by ordinary canonical Maxwell-Boltzmann statistics

Paper de Lactobacillus sake i Lactobacillus curvatus en la maduració del fuet

Peer Reviewe

Lesión digital crónica por atrapamiento intradérmico del anillo: caso clínico

Se presenta un raro caso de lesión crónica por inclusión de un anillo en la base del dedo recubierto por epidermis. No se evidenció lesión neurovascular. La exéresis se realizó bajo anestesia local conservando el dedo. El presente caso ilustra la importancia de prevenir estas lesiones extrayendo los anillos en la fase de edema agudo.An unusual case of embedded ring injury is presented in a patient without neurovascular damage of the finger. The present case remarks the need of removing the ring at the early phase of finger edema

Fronts dynamics in the presence of spatio-temporal structured noises

Front dynamics modeled by a reaction-diffusion equation are studied under the influence of spatio-temporal structured noises. An effective deterministic model is analytical derived where the noise parameters, intensity, correlation time and correlation length appear explicitely. The different effects of these parameters are discussed for the Ginzburg-Landau and Schl\"ogl models. We obtain an analytical expression for the front velocity as a function of the noise parameters. Numerical simulations results are in a good agreement with the theoretical predictions.Comment: 11 pages, 6 figures; REVTEX; to be published in Phys.Rev.E, july 200

Diffusion on a solid surface: Anomalous is normal

We present a numerical study of classical particles diffusing on a solid surface. The particles' motion is modeled by an underdamped Langevin equation with ordinary thermal noise. The particle-surface interaction is described by a periodic or a random two dimensional potential. The model leads to a rich variety of different transport regimes, some of which correspond to anomalous diffusion such as has recently been observed in experiments and Monte Carlo simulations. We show that this anomalous behavior is controlled by the friction coefficient, and stress that it emerges naturally in a system described by ordinary canonical Maxwell-Boltzmann statistics