3,429 research outputs found
On Poisson quasi-Nijenhuis Lie algebroids
We propose a definition of Poisson quasi-Nijenhuis Lie algebroids as a
natural generalization of Poisson quasi-Nijenhuis manifolds and show that any
such Lie algebroid has an associated quasi-Lie bialgebroid. Therefore, also an
associated Courant algebroid is obtained. We introduce the notion of a morphism
of quasi-Lie bialgebroids and of the induced Courant algebroids morphism and
provide some examples of Courant algebroid morphisms. Finally, we use paired
operators to deform doubles of Lie and quasi-Lie bialgebroids and find an
application to generalized complex geometry.Comment: 12 page
On Jacobi quasi-Nijenhuis algebroids and Courant-Jacobi algebroid morphisms
We propose a definition of Jacobi quasi-Nijenhuis algebroid and show that any
such Jacobi algebroid has an associated quasi-Jacobi bialgebroid. Therefore,
also an associated Courant-Jacobi algebroid is obtained. We introduce the
notions of quasi-Jacobi bialgebroid morphism and Courant-Jacobi algebroid
morphism providing also some examples of Courant-Jacobi algebroid morphisms.Comment: 14 pages, to appear in Journal of Geometry and Physic
A RELAÇÃO ENTRE NATUREZA E CAPITAL: reflexões a partir da discussão da Propriedade Privada da Terra
O presente artigo visa discutir a relação da natureza com o capital nos marcos da sociedade capitalista. Parte-se de uma revisão bibliográfica, à luz da teoria marxista, compreendendo que a natureza pode apreendida a partir do materialismo histórico dialético. Nessa direção, buscar-se-á realizar num primeiro momento uma reflexão a partir da constituição da propriedade privada da terra enquanto um elemento fundante para a acumulação e circulação do capital. Num segundo momento, buscar-se-á apontar alguns elementos da contradição entre natureza e capital no atual estágio de desenvolvimento capitalista. Por fim, expõem-se algumas breves considerações finais, sem a pretensão de esgotamento a respeito da temática
A Frame-Based System for Automatic Classification of Semi- Structured Data
The problem of data classification goes back to the definition oftaxonomies covering knowledge areas. With the advent of the Web, the amount of data available increased several orders of magnitude, making manual data classification impossible. This work presents a tool to automatically classify semi-structured data, represented by frames, without any previous knowledge about structured classes. The tool uses a variation of the K-Medoid algorithm and organizes a set of frames into classes, structured as a strict hierarchy
Agrarian analysis of the land multi-functionality in the Alicante Province - Spain
Con el fin de la dictadura franquista (1975) y la entrada en la Unión Europea en 1986, España pasó a recibir un fuerte apoyo financiero (ayudas y subvenciones) del Fondo Europeo de Orientación y GarantÃa Agaria (FEOGA) y de la PolÃtica AgrÃcola Común (PAC). Estas ayudas han tenido una importancia capital en la reciente transformación de los espacios rurales españoles. En el caso de la provincia de Alicante – España, durante las últimas décadas ha pasado por un intenso proceso de alteración territorial y socioambiental, teniendo en el agua el principal factor de sostenibilidad ambiental de los sistemas productivos (industriales y agrÃcolas), sin olvidar el papel que han representado también las fuertes inversiones aplicadas en las áreas turÃsticas. Con relación a la estructura de las explotaciones agropecuarias, en la provincia de Alicante predominan las pequeñas empresas rurales con cultivos de secano (almendro, olivo, viñedo de vinificación, etc.) y también de regadÃo (cÃtricos, hortalizas, frutales, etc.). AsÃ, la implantación de las polÃticas agrÃcolas de la Unión Europea en el campo alicantino, a través del concepto de multifuncionalidad rural, ha ocasionado un aumento de la concentración de las explotaciones, el empobrecimiento y abandono de los pequeños y medianos agricultores, el aumento de la concurrencia de los productos foráneos, los incentivos para la especulación inmobiliaria, teniendo ala turismo como vector principal.The of Franco’s dictatorship (1975) and the admittance to the European Union (1986) enable Spain to get strong financial support (subsides) from the Agrarian Undertaking Funds (FEOGA) and from the Common Agricultural Policy (PAC). These investments had changed Spain into an industrialized and agricultural country. In the last decades the Alicante Province has undergone profound processes of socio-environmental and territorial changes, being water the main aspect of environmental sustainability of the productive systems (industrial and agricultural), as well as the strong investments into touristic areas. As regard to the agrarian structure, inside the Alicante province prevails the small rural properties with dry (grape, olive, etc.) and irrigated (vegetables, citrus, etc.) farming. Therefore, the implantation of agricultural policies from the European Union into the Alicante province, by the concept of rural multi-functionality, has increased the agrarian concentration, the pauperization of the small producers and has increased also the competition with external products and the incentive to the speculation, being the tourism the main vector
Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues
Light propagating in tissue attains a spectrum that varies with location due
to wavelength-dependent fluence attenuation by tissue optical properties, an
effect that causes spectral corruption. Predictions of the spectral variations
of light fluence in tissue are challenging since the spatial distribution of
optical properties in tissue cannot be resolved in high resolution or with high
accuracy by current methods. Spectral corruption has fundamentally limited the
quantification accuracy of optical and optoacoustic methods and impeded the
long sought-after goal of imaging blood oxygen saturation (sO2) deep in
tissues; a critical but still unattainable target for the assessment of
oxygenation in physiological processes and disease. We discover a new principle
underlying light fluence in tissues, which describes the wavelength dependence
of light fluence as an affine function of a few reference base spectra,
independently of the specific distribution of tissue optical properties. This
finding enables the introduction of a previously undocumented concept termed
eigenspectra Multispectral Optoacoustic Tomography (eMSOT) that can effectively
account for wavelength dependent light attenuation without explicit knowledge
of the tissue optical properties. We validate eMSOT in more than 2000
simulations and with phantom and animal measurements. We find that eMSOT can
quantitatively image tissue sO2 reaching in many occasions a better than
10-fold improved accuracy over conventional spectral optoacoustic methods.
Then, we show that eMSOT can spatially resolve sO2 in muscle and tumor;
revealing so far unattainable tissue physiology patterns. Last, we related
eMSOT readings to cancer hypoxia and found congruence between eMSOT tumor sO2
images and tissue perfusion and hypoxia maps obtained by correlative
histological analysis
- …