1,971 research outputs found
Some results on the eigenfunctions of the quantum trigonometric Calogero-Sutherland model related to the Lie algebra E6
The quantum trigonometric Calogero-Sutherland models related to Lie algebras
admit a parametrization in which the dynamical variables are the characters of
the fundamental representations of the algebra. We develop here this approach
for the case of the exceptional Lie algebra E6.Comment: 17 pages, no figure
A New Fast Motion Estimation and Mode Decision algorithm for H.264 Depth Maps encoding in Free Viewpoint TV
In this paper, we consider a scenario where 3D scenes are modeled through a View+Depth representation. This representation is to be used at the rendering side to generate synthetic views for free viewpoint video. The encoding of both type of data (view and depth) is carried out using two H.264/AVC encoders. In this scenario we address the reduction of the encoding complexity of depth data. Firstly, an analysis of the Mode Decision and Motion Estimation processes has been conducted for both view and depth sequences, in order to capture the correlation between them. Taking advantage of this correlation, we propose a fast mode decision and motion estimation algorithm for the depth encoding. Results show that the proposed algorithm reduces the computational burden with a negligible loss in terms of quality of the rendered synthetic views. Quality measurements have been conducted using the Video Quality Metric
An XMM-Newton view of FeK{\alpha} in HMXBs
We present a comprehensive analysis of the whole sample of available
XMM-Newton observations of High Mass X-ray Binaries (HMXBs) until August, 2013,
focusing on the FeK{\alpha} emission line. This line is a key tool to better
understand the physical properties of the material surrounding the X-ray source
within a few stellar radii (the circumstellar medium). We have collected
observations from 46 HMXBs, detecting FeK{\alpha} in 21 of them. We have used
the standard classification of HMXBs to divide the sample in different groups.
We find that: (1) FeK{\alpha} is centred at a mean value of 6.42 keV.
Considering the instrumental and fits uncertainties, this value is compatible
with ionization states lower than FeXVIII. (2) The flux of the continuum is
well correlated with the flux of the line, as expected. Eclipse observations
show that the Fe fluorescence emission comes from an extended region
surrounding the X-ray source. (3) FeK{\alpha} is narrow (width lower than
0.15keV), reflecting that the reprocessing material does not move at high
speeds. We attempt to explain the broadness of the line in terms of three
possible broadening phenomena: line blending, Compton scattering and Doppler
shifts (with velocities of the reprocessing material V=1000-2000 km/s). (4) The
equivalent hydrogen column (NH) directly correlates with the EW of FeK{\alpha},
displaying clear similarities to numerical simulations. It highlights the
strong link between the absorbing and the fluorescent matter. The obtained
results clearly point to a very important contribution of the donors wind in
the FeK{\alpha} emission and the absorption when the donor is a supergiant
massive star.Comment: Accepted for publication in A&A. 13 pages, 16 figures + Appendice
Recommended from our members
Functional Signatures of the Epiphytic Prokaryotic Microbiome of Agaves and Cacti.
Microbial symbionts account for survival, development, fitness and evolution of eukaryotic hosts. These microorganisms together with their host form a biological unit known as holobiont. Recent studies have revealed that the holobiont of agaves and cacti comprises a diverse and structured microbiome, which might be important for its adaptation to drylands. Here, we investigated the functional signatures of the prokaryotic communities of the soil and the episphere, that includes the rhizosphere and phyllosphere, associated with the cultivated Agave tequilana and the native and sympatric Agave salmiana, Opuntia robusta and Myrtillocactus geometrizans by mining shotgun metagenomic data. Consistent with previous phylogenetic profiling, we found that Proteobacteria, Actinobacteria and Firmicutes were the main represented phyla in the episphere of agaves and cacti, and that clustering of metagenomes correlated with the plant compartment. In native plants, genes related to aerobic anoxygenic phototrophy and photosynthesis were enriched in the phyllosphere and soil, while genes coding for biofilm formation and quorum sensing were enriched in both epiphytic communities. In the episphere of cultivated A. tequilana fewer genes were identified, but they belonged to similar pathways than those found in native plants. A. tequilana showed a depletion in several genes belonging to carbon metabolism, secondary metabolite biosynthesis and xenobiotic degradation suggesting that its lower microbial diversity might be linked to functional losses. However, this species also showed an enrichment in biofilm and quorum sensing in the epiphytic compartments, and evidence for nitrogen fixation in the rhizosphere. Aerobic anoxygenic phototrophic markers were represented by Rhizobiales (Methylobacterium) and Rhodospirillales (Belnapia) in the phyllosphere, while photosystem genes were widespread in Bacillales and Cyanobacteria. Nitrogen fixation and biofilm formation genes were mostly related to Proteobacteria. These analyses support the idea of niche differentiation in the rhizosphere and phyllosphere of agaves and cacti and shed light on the potential mechanisms by which epiphytic microbial communities survive and colonize plants of arid and semiarid ecosystems. This study establishes a guideline for testing the relevance of the identified functional traits on the microbial community and the plant fitness
On an approach for computing the generating functions of the characters of simple Lie algebras
We describe a general approach to obtain the generating functions of the
characters of simple Lie algebras which is based on the theory of the quantum
trigonometric Calogero-Sutherland model. We show how the method works in
practice by means of a few examples involving some low rank classical algebras
Los hospitales docentes en la España contemporånea
Desde el siglo XVIII se produjo un avance significativo en la funciĂłn docente del hospital en Europa y en AmĂ©rica del norte. La unificaciĂłn entre la medicina y la cirugĂa y la integraciĂłn de prĂĄcticas clĂnicas en los planes de estudio mĂ©dicos generaron la necesidad de vincular las facultades de medicina a uno o varios hospitales. España se incorporĂł a este proceso progresiva y tardĂamente con sus propias particularidades. El objetivo del artĂculo es presentar una primera aproximaciĂłn a la historia de los hospitales clĂnicos universitarios, haciendo especial hincapiĂ© en la etapa en la que fueron gestionados por el Ministerio de EducaciĂłn. Desde un punto de vista polĂtico se podrĂĄ observar cĂłmo se establecen y desarrollan las relaciones entre las instituciones locales y el Estado central a la hora de gestionar la estructura hospitalaria en el paĂs, y, en concreto, los hospitales docentes.From the 18th century onwards, there were major developments in the teaching function of hospitals in Europe and North America. The unification of medicine and surgery and the integration of clinical practice into the curricula of medical studies created the need to link schools of medicine to hospitals. Spain only joined this process gradually and belatedly and with its own peculiarities. The aim of this article was to outline the history of teaching hospitals in Spain, particularly the university clinical hospitals managed by the Ministry of Education. The study also focuses on political aspects of the issue, especially the establishment and development of the relationship between local institutions and the central state in managing the country's hospital system in general and teaching hospitals in particular
- âŠ