Influence of gas flow rate on liquid distribution in trickle-beds using perforated plates as liquid distributors

Two wire mesh tomography devices and a liquid collector were used to study the influence of the gas flow rate on liquid distribution when fluids distribution on top of the reactor is ensured by a perforated plate. In opposition to most of the studies realized by other authors, conditions in which the gas has a negative impact in liquid distribution were evidenced. Indeed, the obtained results show that the influence of gas flow rate depends on the quality of the initial distribution, as the gas forces the liquid to "respect" the distribution imposed at the top of the reactor. Finally, a comparison between the two measuring techniques shows the limitations of the liquid collector and the improper conclusions to which its use could lead

Tratamiento de última generación químico-mecánico de la caries dental

El tratamiento de última generación químico-mecánico de la caries dental es preconizada por la OMS, como alternativa al tratamiento rehabilitador para países como el nuestro, así como para poblaciones marginales y/o rurales, donde hay dificultades para practicar una odontología convencional, por falta de equipos y/o de energía eléctrica. Esta técnica de restauración TRA, debe ser insertada en todo Programa Preventivo Promocional de Salud Oral. En nuestra Facultad, en que se forman recursos humanos conocedores de su realidad epidemiológica de salud oral nacional, se les debe de preparar en la práctica de Clínica Comunitaria en el ámbito de la periferia de la Universidad, como prácticas preprofesionales, contribuyendo así a la formación de profesionales capaces de enfrentar las adversidades, con armas científicas contundentes, logrando el sueño de nuestra profesión que es el de disminuir los altos índices de prevalencia de las caries dental, pudiendo alcanzar metas de la OMS para el año 2010.El tratamiento de última generación químico-mecánico de la caries dental es preconizada por la OMS, como alternativa al tratamiento rehabilitador para países como el nuestro, así como para poblaciones marginales y/o rurales, donde hay dificultades para practicar una odontología convencional, por falta de equipos y/o de energía eléctrica. Esta técnica de restauración TRA, debe ser insertada en todo Programa Preventivo Promocional de Salud Oral. En nuestra Facultad, en que se forman recursos humanos conocedores de su realidad epidemiológica de salud oral nacional, se les debe de preparar en la práctica de Clínica Comunitaria en el ámbito de la periferia de la Universidad, como prácticas preprofesionales, contribuyendo así a la formación de profesionales capaces de enfrentar las adversidades, con armas científicas contundentes, logrando el sueño de nuestra profesión que es el de disminuir los altos índices de prevalencia de las caries dental, pudiendo alcanzar metas de la OMS para el año 2010

Theory of inelastic scattering from quantum impurities

We use the framework set up recently to compute non-perturbatively inelastic scattering from quantum impurities [G. Zar\'and {\it et al.}, Phys. Rev. Lett. {\bf 93}, 107204 (2004)] to study the the energy dependence of the single particle $S$-matrix and the inelastic scattering cross section for a number of quantum impurity models. We study the case of the spin $S=1/2$ two-channel Kondo model, the Anderson model, and the usual $S=1/2$ single-channel Kondo model. We discuss the difference between non-Fermi liquid and Fermi liquid models and study how a cross-over between the non-Fermi liquid and Fermi liquid regimes appears in case of channel anisotropy for the $S=1/2$ two-channel Kondo model. We show that for the most elementary non-Fermi liquid system, the two-channel Kondo model, half of the scattering remains inelastic even at the Fermi energy. Details of the derivation of the reduction formulas and a simple path integral approach to connect the $T$-matrix to local correlation functions are also presented.Comment: published versio

Tunable Kondo effect in a single donor atom

The Kondo effect has been observed in a single gate-tunable atom. The measurement device consists of a single As dopant incorporated in a Silicon nanostructure. The atomic orbitals of the dopant are tunable by the gate electric field. When they are tuned such that the ground state of the atomic system becomes a (nearly) degenerate superposition of two of the Silicon valleys, an exotic and hitherto unobserved valley Kondo effect appears. Together with the regular spin Kondo, the tunable valley Kondo effect allows for reversible electrical control over the symmetry of the Kondo ground state from an SU(2)- to an SU(4) -configuration.Comment: 10 pages, 8 figure

Body weight distortions in an auditory-driven body illusion in subclinical and clinical eating disorders.

Previous studies suggest a stronger influence of visual signals on body image in individuals with eating disorders (EDs) than healthy controls; however, the influence of other exteroceptive sensory signals remains unclear. Here we used an illusion relying on auditory (exteroceptive) signals to manipulate body size/weight perceptions and investigated whether the mechanisms integrating sensory signals into body image are altered in subclinical and clinical EDs. Participants' footstep sounds were altered to seem produced by lighter or heavier bodies. Across two experiments, we tested healthy women assigned to three groups based on self-reported Symptomatology of EDs (SED), and women with Anorexia Nervosa (AN), and used self-report, body-visualization, and behavioural (gait) measures. As with visual bodily illusions, we predicted stronger influence of auditory signals, leading to an enhanced body-weight illusion, in people with High-SED and AN. Unexpectedly, High-SED and AN participants displayed a gait typical of heavier bodies and a widest/heaviest visualized body in the 'light' footsteps condition. In contrast, Low-SED participants showed these patterns in the 'heavy' footsteps condition. Self-reports did not show group differences. The results of this pilot study suggest disturbances in the sensory integration mechanisms, rather than purely visually-driven body distortions, in subclinical/clinical EDs, opening opportunities for the development of novel diagnostic/therapeutic tools

Cardiac abnormalities in the toxic oil syndrome, with comparative observations on the eosinophilia-myalgia syndrome

AbstractEarly in the course of studies of the Spanish toxic oil syndrome it was recognized that vascular lesions were a major problem, most logically attributable to endothelial damage by the toxic oil. However, most clinical attention has been directed to the pulmonary complications and the evolution into a scleroderma-like illness later. p]In this study of 11 victims of the toxic oil syndrome careful postmortem studies of the coronary arteries and conduction system and neural structures of the heart demonstrated major injury to all those components of the heart. Obliterative fibrosis of the sinus node in four cases resembled findings in fatal scleroderma heart disease, and in eight the cardiac lesions resembled those of lupus erythematosus.The more impressive pathologic features involved the coronary arteries and neural structures, which were abnormal in every heart. The arterial disease included widespread focal fibromuscular dysplasia, but there was also an unusual myointimal proliferative degeneration of both small and large coronary arteries in five patients, four of whom were young women. In two hearts, portions of the inner wall of the sinus node artery had actually detached and embolized downstream. Coronary arteritis was rarely found. Inflammatory and noninflammatory degeneration of cardiac nerves was widespread. Fatty infiltration, fibrosis and degeneration were present in the coronary chemoreceptor.In most respects these cardiac abnormalities resemble those described in the eosinophilia-myalgia syndrome caused by an altered form of l-tryptophan. In both diseases there is good reason to anticipate more clinical cardiac difficulties than have so far been reported, and even more basis for future concern, especially relative to coronary disease and cardiac electrical instability

Design, Participation, and Social Change: What Design in Grassroots Spaces Can Teach Learning Scientists

hile a science of design (and theory of learning) is certainly useful in design-based research, a participatory design research framework presents an opening for learning scientists to rethink design and learning as processes. Grounded in the autoethnographic investigation of a grassroots organization\u27s design of a local campaign, the author traces the successive transformations of design artifacts, delineating a narrative character to design within grassroots spaces. One major lesson is that centering the question of participation is not just about including historically marginalized peoples at the core of design; it has the potential to “desettle” projects at a fundamental level, challenging dominant epistemologies that inform the practices of learning scientists, and thus transforming the field in ways that have yet to be systematically explored. More broadly, this study highlights the need for future research on design practices as they take form within understudied spaces, such as grassroots organizations

SOLIDEZ DE LOS AGREGADOS PÉTREOS MEDIANTE LA ADICION SULFATO DE MAGNESIO

El concreto es un material heterogéneo que depende de numerosas variables. Esto da lugar a que haya variación en las propiedades del mismo, lo cual se verá reflejado en la duración y calidad del producto final elaborado con este. El concreto preparado con ciertos agregados pétreos, puede ocasionar posibles deterioros, en ambientes favorables a la ocurrencia de reacciones químicas entre los agregados y los álcalis presentes en el cemento. Este artículo presenta el análisis del comportamiento de unas muestras de agregado pétreo, tomadas de la Cantera vista Hermosa (Mosquera) y la mina Cemex (Apulo), el objetivo del ensayo fue determinar la solidez de los agregados frente a la acción del sulfato de magnesio; para llegar a esto se sometieron las muestras del agregado, a la acción de ciclos de exposición y secado en una solución saturada de sulfato de magnesio y se determinaron los efectos de esta sobre las partículas del agregado. La solidez de los agregados frente a la acción del sulfato, arrojo para la cantera de Vista Hermosa (Mosquera) un comportamiento menos favorable que para la Mina Cemex (Apulo). La Cantera Vista Hermosa presento materiales altamente porosos, lo cual ocasionó disgregación de los mismos debido a su friabilidad, a pesar de ello el contenido de partículas oxidadas fue inferior que en la Mina Cemex. Así mismo con esta investigación se pretende comprender los tipos de reacciones químicas que se pueden generar a causa de los agregados pétreos empleados en la elaboración de concretos, y la incidencia de estos en deterioro en las estructuras

Quantum phase transition in a two-channel-Kondo quantum dot device

We develop a theory of electron transport in a double quantum dot device recently proposed for the observation of the two-channel Kondo effect. Our theory provides a strategy for tuning the device to the non-Fermi-liquid fixed point, which is a quantum critical point in the space of device parameters. We explore the corresponding quantum phase transition, and make explicit predictions for behavior of the differential conductance in the vicinity of the quantum critical point