Quantum critical behavior of electrons at the edge of charge order

We consider quantum critical points (QCP) in which quantum fluctuations associated with charge rather than magnetic order induce unconventional metallic properties. Based on finite-T calculations on a two-dimensional extended Hubbard model we show how the coherence scale T* characteristic of Fermi liquid behavior of the homogeneous metal vanishes at the onset of charge order. A strong effective mass enhancement reminiscent of heavy fermion behavior indicates the possible destruction of quasiparticles at the QCP. Experimental probes on quarter-filled layered organic materials are proposed for unveiling the behavior of electrons across the quantum critical region.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

Light-cone quantization of two dimensional field theory in the path integral approach

A quantization condition due to the boundary conditions and the compatification of the light cone space-time coordinate $x^-$ is identified at the level of the classical equations for the right-handed fermionic field in two dimensions. A detailed analysis of the implications of the implementation of this quantization condition at the quantum level is presented. In the case of the Thirring model one has selection rules on the excitations as a function of the coupling and in the case of the Schwinger model a double integer structure of the vacuum is derived in the light-cone frame. Two different quantized chiral Schwinger models are found, one of them without a $\theta$-vacuum structure. A generalization of the quantization condition to theories with several fermionic fields and to higher dimensions is presented.Comment: revtex, 14 p

Electron-phonon coupling in 122 Fe pnictides analyzed by femtosecond time-resolved photoemission

Based on results from femtosecond time-resolved photoemission, we compare three different methods for determination of the electron-phonon coupling constant {\lambda} in Eu and Ba-based 122 FeAs compounds. We find good agreement between all three methods, which reveal a small {\lambda} < 0.2. This makes simple electron-phonon mediated superconductivity unlikely in these compounds.Comment: 11 pages, 3 figure

Conserved Ising Model on the Human Connectome

Dynamical models implemented on the large scale architecture of the human brain may shed light on how function arises from the underlying structure. This is the case notably for simple abstract models, such as the Ising model. We compare the spin correlations of the Ising model and the empirical functional brain correlations, both at the single link level and at the modular level, and show that their match increases at the modular level in anesthesia, in line with recent results and theories. Moreover, we show that at the peak of the specific heat (the \it{critical state}) the spin correlations are minimally shaped by the underlying structural network, explaining how the best match between structure and function is obtained at the onset of criticality, as previously observed. These findings confirm that brain dynamics under anesthesia shows a departure from criticality and could open the way to novel perspectives when the conserved magnetization is interpreted in terms of an homeostatic principle imposed to neural activity

Morphological characterisation of the coronary arteries in African sheep (Ovis orientalis). Differential analysis with those of humans and other animal species

Background: Despite the importance of the coronary system in the African sheep as a possible experimental model, there is little information about this particular vascular system. The objective of this investigation was to characterise morpho- logically the coronary arteries and their branches in African sheep.  Materials and methods: This descriptive cross-sectional study evaluated the coronary arteries and their branches of 62 hearts of short hair sheep. The right and left coronary ostia were perfused with a semi-synthetic resin (Palatal GP40L 85%; styrene 15%) dyed with mineral red. The morphological characteristics were evaluated using a digital calibrator and the biometrics of the coronary arteries and their branches were registered.  Results: The right coronary artery had a proximal calibre of 2.11 ± 0.46 mm. The subsinusal interventricular branch ended at the middle third of the homonym sulcus in 19 (30.6%) specimens. The left coronary artery had a diameter of 5.38 ± ± 1.59 mm and a length of 4.67 ± 3.32 mm. This artery bifurcated itself in the paraconal interventricular branch and the left circumflex branch in 57 (91.9%) hearts and trifurcated with an additional left diagonal branch in 5 (8.1%) spec- imens. Left coronary artery dominance was observed in 51 (82.3%) specimens, whereas in 11 (17.7%) cases the coronary circulation dominance was balanced.  Conclusions: Due to the similitude in the features of the coronary arteries between African sheep and humans, this animal model can be proposed for procedural and haemodynamic activities.

Analysis of embedded CORBA middleware performance on urban distributed transportation equipments

The increasing number of ITS (Intelligent Transportation Systems) equipment spread across cities offers tre- mendous possibilities in the development of distributed smart environments. A middleware layer located be- tween the operating system and the fi nal application can be used for the communication among the equipment to spontaneously act and cooperate among themselves. However, this middleware layer has also a computational cost that should be quanti fi ed as it can affect the main application. This paper de fi nes a methodology for such quanti fi cation using as case example a modern ITS equipment related to vehicle tracking using arti fi cial vision. Experimental results illustrate the proposed methodology.Ministerio de Educación y Ciencia DPI2007-60128Consejería de Innovación, Ciencia y Empresa P07-TIC-0262

Plataforma para el desarrollo de sensores inteligentes y sistemas microprocesadores

En un esfuerzo por acercar a los alumnos el diseño y desarrollo de sensores inteligentes y sistemas microprocesadores actuales, el Departamento de Ingeniería Electrónica ha desarrollado un prototipo de sistema domótico, articulado en torno a un bus CAN, con el que se pretende hacer ver a los alumnos la importancia y las posibilidades que ofrecen estos sistemas estrechamente ligados a la instrumentación.Ministerio de Educación y Ciencia (TSI2005-24 068-E)

Controller area network domotic prototype using GPRS and Ethernet interfaces for virtual monitoring applications

Nowadays there are three basic technological supports which are suffering an enormous development. First we could mention field buses applications, which are getting more and more important in domotics. The second one, Web and Internet applications, is becoming popular and accessible in the last time. Finally, the third support, based on GSM networking, make one of the most important development focus up to now. The proposed system is based on the mentioned idea, the importance of the nexus between these three technological supports, developing a domotic system using CAN, a field bus which has been used mainly in automotive, and interconnected to the Internet employing Ethernet networks and GSM nodes via GPRS protocol