H infinity control design for generalized second order systems based on acceleration sensitivity function

This article presents an Hinfinty control design method based on the Acceleration Sensitivity (AS) function. This approach can be applied to any fully actuated generalized second order system. In this framework, classical modal specifications(pulsations / damping ratios) are expressed in terms of Hinfinty templates allowing other frequency domain specifications to betaken into account. Finally, a comparison between AS with a more classical Hinfinty approach and with the Cross Standard Form(CSF) is presented. A 2 degrees of freedom spring-damper-mass academic example is used to illustrate the properties of the AS,though this method was developed and is used for atmospheric reentry control design

Launcher attitude control: some additional design and optimization tools

This paper deals with the launcher attitude control during atmospheric flight. A two step approach combining an H1 control design and an optimization procedure is proposed. The first step is multi-objective stationary H1 design based on the Cross Standard Form. It provides easily a first rough solution from a few physical tuning parameters. The second step is a fine tuning using an multi-constraint satisfaction algorithm. This algorithm enables the certification criteria computed on the validation model to be met and is also used to propagate the nominal tuning to the full flight envelope

Oportunidades y límites de la nueva información geográfica para uso turístico en destino: El caso de la ciudad de Barcelona

Contar con un buen mapa turístico en destino es fundamental para la óptima orientación y localización del visitante, erigiéndose como instrumento indispensable que acompaña y guía durante toda la estancia. En este mismo contexto, la aparición en el panorama turístico de una nueva forma de consumir la información geográfica en manos del turista - incorporada en los modernos dispositivos móviles-, está aportando un valor diferencial que los mapas convencionales no llegan a alcanzar. Mayor dinamismo, actualización de contenidos, grandes posibilidades de la geolocalización, son entre muchos otros, factores suficientes que suponen una nueva manera de descubrir el territorio turístico. A partir de un estudio llevado a cabo por el Grupo de Investigación de Turismo, Cultura y Territorio de la Escuela Universitaria de Hotelería y Turismo CETT-UB, se desgranan cuáles son los factores que motivan a los turistas en decantarse, o no, por esta nueva cartografía. Tomando como marco de referencia la ciudad de Barcelona, se analiza la variedad existente en información geográfica que tiene el visitante a su disposición para conocer este destino. De este modo se pretende evidenciar cuáles son las principales ventajas e inconvenientes de optar por un formato u otro para desplazarse por el espacio turístico

A reason why the ERBB2 gene is amplified and not mutated in breast cancer

Alterations of receptor-type tyrosine kinases (RTK) are frequent in human cancers. They can result from translocation, mutation or amplification. The ERBB2 RTK is encoded by a gene that is amplified in about 20% breast cancers. The question is: why is this RTK specifically subjected to this type of alteration? We propose that ERBB2 gene amplification is used to overcome repression of its expression by sequence-specific transcription factors

Chronologie des occupations précolombiennes de l'île de Saint-Martin (Petites Antilles) et relations avec les paléoenvironnements

International audienceLa séquence de l'occupation précolombienne de l'île de Saint-Martin couvre une fourchette chronologique d'environ 4000 ans, de 2500 av. J.C. à 1500 ap.J.C.. On perçoit trois principales phases culturelles : une période précéramique suivie de deux phases céramiques, saladoïde et postsaladoïde. Deux référentiels chronologiques sont en cours d'élaboration. Le premier concerne l'occupation humaine restituée à partir de l'analyse de gisements précolombiens récemment documentés. Le second, qui se rapporte à l'évolution des paléomilieux, est construit à partir d'une analyse pluridisciplinaire du remplissage sédimentaire de plusieurs lagunes. La séquence étudiée a fourni à la base une datation vers 2900 av. J.C., elle couvre toute la période précolombienne. Les premiers résultats montrent des possibilités de corrélations entre les phases de transitions culturelles et les changements paléoclimatiques durant l'Holocène

The popliteal cyst

A popliteal cyst, originally called Baker's cyst, is a synovial fluid-filled mass located in the popliteal fossa. The most common synovial popliteal cyst is considered to be a distension of the bursa located beneath the medial head of the gastrocnemius muscle. Usually, in an adult patient, an underlying intra-articular disorder is present. In children, the cyst can be isolated and the knee joint normal. The anatomy, etiopathogenesis, clinical presentation, differential diagnosis, imaging and treatment modalities of the popliteal cyst are presented. The authors try to answer some questions dealing with this condition. Is the cyst isolated, can it be treated as such, is its origin always well-defined and does surgical excision provide a permanent cure