Online measurement and evaluation of the Er:YAG laser ablation process using an integrated OCT system

Laser surgery has gained clinical importance due to numerous advantages including contact-free processing, arbitrary cutting geometries, and high precision. However, online process control remains a challenge for widespread clinical use. Therefore, we established a combined setup of a pulsed Er:YAG laser ( = 2940 nm) and an optical coherence tomogra-phy (OCT) ( = 930 nm) for in situ monitoring of hard tissue ablation. The optical setup facilitates an interactive control of the laser ablation depth and remaining tissue strength through the depth resolution of OCT. The 3D OCT data-set, which is acquired after ablation, provides contours and layer thicknesses

Chargino Production at LEP2 in a Supergravity Model

In the framework of a particular supergravity model which provides a natural solution to the $\mu$--problem we show how the discovery of a chargino at LEP2 and the measurement of its mass and production cross--section, together with the measurement of the mass of the lightest neutralino, would determine the entire Higgs and SUSY spectrum. We give detailed predictions for the Higgs and SUSY spectrum as a function of the chargino production cross--section, for constant values of the lightest chargino and gluino masses.Comment: 11 pages, latex, 4 figures uufile

The Cyborg Astrobiologist: Testing a Novelty-Detection Algorithm on Two Mobile Exploration Systems at Rivas Vaciamadrid in Spain and at the Mars Desert Research Station in Utah

(ABRIDGED) In previous work, two platforms have been developed for testing computer-vision algorithms for robotic planetary exploration (McGuire et al. 2004b,2005; Bartolo et al. 2007). The wearable-computer platform has been tested at geological and astrobiological field sites in Spain (Rivas Vaciamadrid and Riba de Santiuste), and the phone-camera has been tested at a geological field site in Malta. In this work, we (i) apply a Hopfield neural-network algorithm for novelty detection based upon color, (ii) integrate a field-capable digital microscope on the wearable computer platform, (iii) test this novelty detection with the digital microscope at Rivas Vaciamadrid, (iv) develop a Bluetooth communication mode for the phone-camera platform, in order to allow access to a mobile processing computer at the field sites, and (v) test the novelty detection on the Bluetooth-enabled phone-camera connected to a netbook computer at the Mars Desert Research Station in Utah. This systems engineering and field testing have together allowed us to develop a real-time computer-vision system that is capable, for example, of identifying lichens as novel within a series of images acquired in semi-arid desert environments. We acquired sequences of images of geologic outcrops in Utah and Spain consisting of various rock types and colors to test this algorithm. The algorithm robustly recognized previously-observed units by their color, while requiring only a single image or a few images to learn colors as familiar, demonstrating its fast learning capability.Comment: 28 pages, 12 figures, accepted for publication in the International Journal of Astrobiolog

Classically time-controlled quantum automata

In this paper we introduce classically time-controlled quantum automata or CTQA, which is a slight but reasonable modification of Moore-Crutchfield quantum finite automata that uses time-dependent evolution operators and a scheduler defining how long each operator will run. Surprisingly enough, time-dependent evolutions provide a significant change in the computational power of quantum automata with respect to a discrete quantum model. Furthermore, CTQA presents itself as a new model of computation that provides a different approach to a formal study of “classical control, quantum data” schemes in quantum computing.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Cáncer de colon y recto

JUSTIFICACIÓN: el cáncer de colon y recto es la tercera neoplasia más frecuente en el mundo, en la cual se han presentado notables avances en el tamizaje, diagnóstico y tratamiento. OBJETIVO: realizar una revisión de los avances en la epidemiología, diagnóstico y terapéutica del cáncer de colon y recto. METODOLOGÍA DE BÚSQUEDA: se realizó una búsqueda en Medline, según la metodología Cochrane, de artículos publicados desde enero de 1980 a enero de 2006 usando los términos colorectal carcinoma; de esta búsqueda se seleccionaron los manuscritos considerados relevantes por parte de los autores. CONCLUSIONES: se han producido notables avances en el diagnóstico precoz, y tratamiento del cáncer de colon y recto lo cual se traduce en un mejor pronóstico para los pacientes afectados por esta patología.  Palabras clave: Neoplasias del Colon. Epidemiología. Diagnóstico. Tratamiento.&nbsp

Colloquium: quantum coherence as a resource

The coherent superposition of states, in combination with the quantization of observables, represents one of the most fundamental features that mark the departure of quantum mechanics from the classical realm. Quantum coherence in many-body systems embodies the essence of entanglement and is an essential ingredient for a plethora of physical phenomena in quantum optics, quantum information, solid state physics, and nanoscale thermodynamics. In recent years, research on the presence and functional role of quantum coherence in biological systems has also attracted a considerable interest. Despite the fundamental importance of quantum coherence, the development of a rigorous theory of quantum coherence as a physical resource has only been initiated recently. In this Colloquium we discuss and review the development of this rapidly growing research field that encompasses the characterization, quantification, manipulation, dynamical evolution, and operational application of quantum coherence

MIUSCAT: extended MILES spectral coverage. I. Stellar populations synthesis models

We extend the spectral range of our stellar population synthesis models based on the MILES and CaT empirical stellar spectral libraries. For this purpose we combine these two libraries with the Indo-U.S. to construct composite stellar spectra to feed our models. The spectral energy distributions (SEDs) computed with these models and the originally published models are combined to construct composite SEDs for single-age, single-metallicity stellar populations (SSPs) covering the range 3465 - 9469\AA at moderately high, and uniform, resolution (FWHM=2.51\AA). The colours derived from these SSP SEDs provide good fits to Galactic globular cluster data. We find that the colours involving redder filters are very sensitive to the IMF, as well as a number of features and molecular bands throughout the spectra. To illustrate the potential use of these models we focus on the NaI doublet at 8200 \AA and with the aid of the newly synthesized SSP model SEDs we define a new IMF-sensitive index that is based on this feature, which overcomes various limitations from previous index definitions for low velocity dispersion stellar systems. We propose an index-index diagram based on this feature and the neighboring CaII triplet at 8600 \AA, to constrain the IMF if the age and [Na/Fe] abundance are known. Finally we also show a survey-oriented spectrophotometric application which evidences the accurate flux calibration of these models for carrying out reliable spectral fitting techniques. These models are available through our user-friendly website.Comment: 16 pages, 17 figures, 2 tables; MNRAS in press. Model predictions available at our website: http://miles.iac.e

Evidence of strong quasar feedback in the early Universe

Most theoretical models invoke quasar driven outflows to quench star formation in massive galaxies, this feedback mechanism is required to account for the population of old and passive galaxies observed in the local universe. The discovery of massive, old and passive galaxies at z=2, implies that such quasar feedback onto the host galaxy must have been at work very early on, close to the reionization epoch. We have observed the [CII]158um transition in SDSSJ114816.64+525150.3 that, at z=6.4189, is one of the most distant quasars known. We detect broad wings of the line tracing a quasar-driven massive outflow. This is the most distant massive outflow ever detected and is likely tracing the long sought quasar feedback, already at work in the early Universe. The outflow is marginally resolved on scales of about 16 kpc, implying that the outflow can really affect the whole galaxy, as required by quasar feedback models. The inferred outflow rate, dM/dt > 3500 Msun/yr, is the highest ever found. At this rate the outflow can clean the gas in the host galaxy, and therefore quench star formation, in a few million years.Comment: 5 pages, 3 figures, accepted for publication in MNRAS Letter

MODELADO Y SIMULACIÓN DEL CONTROL DE VELOCIDAD DE UN MOTOR HIDRÁULICO

En este artículo se presenta una metodología de selección de un motor hidráulico y el control de su velocidad, a partir de unos requerimientos de funcionamiento. Se presenta el modelado del sistema, la selección de los componentes, y se presentan los resultados de la simulación

Growth of Calcium Carbonate in the Presence of Cr(VI)

The extended use of hexavalent chromium Cr(VI) compounds in industrial processes caused a significant increase of the concentration of this highly toxic heavy metal in natural environments. In order to investigate the influence of Cr(VI) in the formation of CaCO3, crystallization experiments were carried out in a double diffusion system, using silica hydrogel with different Cr(VI) contents as the growth medium. Crystalline products were examined by scanning electron microscopy, Raman spectroscopy, electron microprobe analysis, and single crystal X-ray diffraction. Increasing Cr(VI) concentration caused inhibition of the nucleation and growth of calcite and promoted the formation of the metastable polymorphs aragonite and vaterite. This effect correlated with a decrease of crystal size. Furthermore, the habit of calcite crystals changed with increasing Cr(VI) concentrations from {104} to forms increasingly elongated parallel to the c-axis. Raman spectroscopy, single crystal X-ray diffraction (XRD), and electron microprobe analysis (EMPA) gave strong indications of an isomorphic anion substitution of trigonal planar carbonate by the tetrahedral chromate within the calcite lattice. The apparent partitioning coefficients of Cr(VI) into calcite determined in this work suggest that the fate of this pollutant in natural environments can be significantly influenced by CaCO3 precipitation processes