Indicaciones en la colocación de un mantenedor de espacio

La pérdida prematura de un diente deciduo puede causar, en general, un problema potencial en la alineación de la arcada dentaria. En este artículo se comentan las consecuencias que pueden ocurrir tras la pérdida prematura de los diferentes dientes deciduos, en los distintos momentos del desarrollo de la oclusión, indicando aquellas situaciones más convenientes para la colocación de un mantenedor de espacio, así como el tipo más adecuado para cada una de estas situaciones.

Aproximación al tratamiento precoz de la mordida cruzada anterior

La mordida cruzada anterior debe tratarse precozmente, para mejorar el entorno dentoalveolar y favorecer el crecimiento correcto de los maxilares. En este artículo se analizan: la etiología, el diagnóstico de la mordida cruzada anterior y se mencionan diferentes formas de tratamiento de esta maloclusión en dentición primaria y mixta.

La mordida cruzada posterior. Razones y medios para su tratamiento precoz

En este artículo se señalan las causas que pueden producir una mordida cruzada posterior, se exponen las razones para su corrección precoz, en el período de dentición primaría y en la primera fase de dentición mixta y se mencionan los diferentes medios de tratamiento de que dispone el clínico, indicando cuáles pueden ser más adecuados para esta edad temprana.

Study of post-deposition contamination in low-temperature deposited polysilicon films

The presence of hydrogen in polysilicon films obtained at low temperatures by hot-wire CVD and the post-deposition oxidation by air-exposure of the films are studied in this paper. The experimental results from several characterization techniques (infrared spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry and wavelength dispersive spectroscopy) showed that hydrogen and oxygen are homogeneously distributed at grain boundaries throughout the depth of the films. Hydrogen is introduced during the growth process and its concentration is higher in samples deposited at lower temperatures. Oxygen diffuses along the grain boundaries and binds to silicon atoms, mainly in Si 2O groups.

Effect of meal ingestion on liver stiffness in patients with cirrhosis and portal hypertension.

BACKGROUND AND AIMS: Liver stiffness is increasingly used in the non-invasive evaluation of chronic liver diseases. Liver stiffness correlates with hepatic venous pressure gradient (HVPG) in patients with cirrhosis and holds prognostic value in this population. Hence, accuracy in its measurement is needed. Several factors independent of fibrosis influence liver stiffness, but there is insufficient information on whether meal ingestion modifies liver stiffness in cirrhosis. We investigated the changes in liver stiffness occurring after the ingestion of a liquid standard test meal in this population. METHODS: In 19 patients with cirrhosis and esophageal varices (9 alcoholic, 9 HCV-related, 1 NASH; Child score 6.9±1.8), liver stiffness (transient elastography), portal blood flow (PBF) and hepatic artery blood flow (HABF) (Doppler-Ultrasound) were measured before and 30 minutes after receiving a standard mixed liquid meal. In 10 the HVPG changes were also measured. RESULTS: Post-prandial hyperemia was accompanied by a marked increase in liver stiffness (+27±33%; p<0.0001). Changes in liver stiffness did not correlate with PBF changes, but directly correlated with HABF changes (r = 0.658; p = 0.002). After the meal, those patients showing a decrease in HABF (n = 13) had a less marked increase of liver stiffness as compared to patients in whom HABF increased (n = 6; +12±21% vs. +62±29%,p<0.0001). As expected, post-prandial hyperemia was associated with an increase in HVPG (n = 10; +26±13%, p = 0.003), but changes in liver stiffness did not correlate with HVPG changes. CONCLUSIONS: Liver stiffness increases markedly after a liquid test meal in patients with cirrhosis, suggesting that its measurement should be performed in standardized fasting conditions. The hepatic artery buffer response appears an important factor modulating postprandial changes of liver stiffness. The post-prandial increase in HVPG cannot be predicted by changes in liver stiffness.

Aportaciones a la mejora de la evaluación de la accesibilidad en entornos web 2.0 interactivos administrados mediante sistemas de gestión de contenido

El objetivo final de este trabajo es estudiar las metodologías, técnicas y herramientas que faciliten el proceso de desarrollo de entornos web interactivos dentro de lo que se conoce como paradigma de la web 2.0. Inicialmente se analiza el estado del arte en cuanto a la accesibilidad de entornos digitales y se presentan las características y problemas específicos de accesibilidad de los sistemas de gestión de contenido (o entornos CMS). Posteriormente se describe una metodología para la ingeniería de la accesibilidad en entornos web 2.0. También se presenta un framework con la intención de sustentar la metodología propuesta con el mayor grado de automatización y disminución del esfuerzo requerido por parte de las personas encargadas de gestionar la evaluación de la accesibilidad. Finalmente, se presentan una serie de prototipos que estudian el resultado que ha de ofrecer el framework respecto a diversos casos de estudio referentes a entornos web 2.0 administrados mediante gestores de contenido, concretamente un entorno genérico, una wiki y un blog.

A Semantic wiki for quality management in software development projects

Quality management has become a strategic issue for organisations and is very valuable to produce quality software. However, quality management systems (QMS) are not easy to implement and maintain. The authors' experience shows the benefits of developing a QMS by first formalising it using semantic web ontologies and then putting them into practice through a semantic wiki. The QMS ontology that has been developed captures the core concepts of a traditional QMS and combines them with concepts coming from the MPIu'a development process model, which is geared towards obtaining usable and accessible software products. Then, the ontology semantics is directly put into play by a semantics-aware tool, the Semantic MediaWiki. The developed QMS tool is being used for 2 years by the GRIHO research group, where it has manages almost 50 software development projects taking into account the quality management issues. It has also been externally audited by a quality certification organisation. Its users are very satisfied with their daily work with the tool, which manages all the documents created during project development and also allows them to collaborate, thanks to the wiki features.

Guia de contingut digital accessible: vídeo

La guia consta d’un conjunt de documents en format pdf i d’una web (http://www.videoaccessible.udl.cat) que es complementen per donar pautes, recomanacions i exemples necessaris per poder mostrar informació en format vídeo digital accessible per a les persones amb diferents discapacitats.

Controlling the spin of metal atoms adsorbed on oxide surfaces: Ni on regular and defective sites of the MgO(001) surface

We have analyzed the relative energy of nonmagnetic and magnetic low-lying electronic states of Ni atoms adsorbed on regular and defective sites of the MgO(001) surface. To this end cluster and periodic surface models are used within density functional theory. For Ni atoms adsorbed on oxygen vacancies at low coverage, the interaction energy between the metal and the support is much larger than on regular sites. Strong bonding results in a diamagnetic adsorbed species and the energy required to reach the high-spin state increases. Moreover, a correlation appears between the low-spin to high-spin energy difference and the interaction energy hypothesizing that it is possible to prepare the surface to tune the high-spin to low-spin energy difference. Magnetic properties of adsorbed thin films obtained upon increasing coverage are more difficult to interpret. This is because the metallic bond is readily formed and dominates over the effect of the atoms directly bound to the vacancy.

Determinación de la paleosalinidad, mediante la relación Br/Cl, en las sales de la cuenca potásica catalana (Sallent, Barcelona, España)

Debido a su acumdación en las salmueras de las cubetas de deposición evaporítica, el Br se concentra progresivamente en los ultimos precipitados de los cloruros. La relación Br/Cl ha sido utilizada (BOEKE y EITEL, 1923; D'ANS y KÜHN, 1944) para determinar variaciones en la concentración de la salmuera durante la deposición evaporítica. Para la determinación cuantitativa del Br y CL en varias muestras recogidas en la explotación de Sallent, se ha utilizado la fluorescencia de rayos X.

Effect of meal ingestion on liver stiffness in patients with cirrhosis and portal hypertension.

BACKGROUND AND AIMS: Liver stiffness is increasingly used in the non-invasive evaluation of chronic liver diseases. Liver stiffness correlates with hepatic venous pressure gradient (HVPG) in patients with cirrhosis and holds prognostic value in this population. Hence, accuracy in its measurement is needed. Several factors independent of fibrosis influence liver stiffness, but there is insufficient information on whether meal ingestion modifies liver stiffness in cirrhosis. We investigated the changes in liver stiffness occurring after the ingestion of a liquid standard test meal in this population. METHODS: In 19 patients with cirrhosis and esophageal varices (9 alcoholic, 9 HCV-related, 1 NASH; Child score 6.9±1.8), liver stiffness (transient elastography), portal blood flow (PBF) and hepatic artery blood flow (HABF) (Doppler-Ultrasound) were measured before and 30 minutes after receiving a standard mixed liquid meal. In 10 the HVPG changes were also measured. RESULTS: Post-prandial hyperemia was accompanied by a marked increase in liver stiffness (+27±33%; p<0.0001). Changes in liver stiffness did not correlate with PBF changes, but directly correlated with HABF changes (r = 0.658; p = 0.002). After the meal, those patients showing a decrease in HABF (n = 13) had a less marked increase of liver stiffness as compared to patients in whom HABF increased (n = 6; +12±21% vs. +62±29%,p<0.0001). As expected, post-prandial hyperemia was associated with an increase in HVPG (n = 10; +26±13%, p = 0.003), but changes in liver stiffness did not correlate with HVPG changes. CONCLUSIONS: Liver stiffness increases markedly after a liquid test meal in patients with cirrhosis, suggesting that its measurement should be performed in standardized fasting conditions. The hepatic artery buffer response appears an important factor modulating postprandial changes of liver stiffness. The post-prandial increase in HVPG cannot be predicted by changes in liver stiffness.

Simple sugar intake and hepatocellular carcinoma: epidemiological and mechanistic insight

Sugar intake has dramatically increased during the last few decades. Specifically, there has been a clear trend towards higher consumption of fructose and high fructose corn syrup, which are the most common added sugars in processed food, soft drinks and other sweetened beverages. Although still controversial, this rising trend in simple sugar consumption has been positively associated with weight gain and obesity, insulin resistance and type 2 diabetes mellitus and non-alcoholic fatty liver disease. Interestingly, all of these metabolic alterations have also been related to the development of hepatocellular carcinoma. The purpose of this review is to discuss the evidence coming from epidemiological studies and data from animal models relating the consumption of simple sugars, and specifically fructose, with an increased risk of hepatocellular carcinoma and to gain insight into the putative molecular mechanisms involved.

Sinusoidal Endothelial Dysfunction Precedes Inflammation and Fibrosis in a Model of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. Most morbidity associated with the metabolic syndrome is related to vascular complications, in which endothelial dysfunction is a major pathogenic factor. However, whether NAFLD is associated with endothelial dysfunction within the hepatic vasculature is unknown. The aims of this study were to explore, in a model of diet-induced overweight that expresses most features of the metabolic syndrome, whether early NAFLD is associated with liver endothelial dysfunction. Wistar Kyoto rats were fed a cafeteria diet (CafD; 65% of fat, mostly saturated) or a control diet (CD) for 1 month. CafD rats developed features of the metabolic syndrome (overweight, arterial hypertension, hypertryglyceridemia, hyperglucemia and insulin resistance) and liver steatosis without inflammation or fibrosis. CafD rats had a significantly higher in vivo hepatic vascular resistance than CD. In liver perfusion livers from CafD rats had an increased portal perfusion pressure and decreased endothelium-dependent vasodilation. This was associated with a decreased Akt-dependent eNOS phosphorylation and NOS activity. In summary, we demonstrate in a rat model of the metabolic syndrome that shows features of NAFLD, that liver endothelial dysfunction occurs before the development of fibrosis or inflammation.

Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: Application to Escherichia coli

The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to pre-concentrate the sample, and an impedance analyser, to measure concentrated bacteria levels. The system is composed by a single micro-fluidic chamber with interdigitated electrodes and a instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time.