Antineutrophil cytoplasmic antibodies in sera from colectomised ulcerative colitis patients and its relation to the presence of pouchitis.

BACKGROUND: Few studies have evaluated the influence of colectomy on antineutrophil cytoplasmic antibody (ANCA) positivity in ulcerative colitis (UC). In small series of patients it has been suggested that ANCA positivity in UC might be predictive for development of pouchitis after colectomy. AIMS: To assess the prevalence of ANCA in UC patients treated by colectomy and a Brooke's ileostomy (UC-BI) or ileal pouch anal anastomosis (UC-IPAA), and the relation between the presence of ANCA, the type of surgery, and the presence of pouchitis. SUBJECTS: 63 UC patients treated by colectomy (32 with UC-BI and 31 with UC-IPAA), 54 UC, and 24 controls. METHODS: Samples were obtained at least two years after colectomy. ANCA were detected by indirect immunofluorescent assay. RESULTS: There were no differences between patients with (36.3%) or without pouchitis (35.0%) and between patients with UC (55%), UC-BI (40.6%), and UC-IPAA (35.4%). However, ANCA prevalence significantly decreases in the whole group of operated patients (38.0%) compared with non-operated UC (p = 0.044). CONCLUSIONS: The prevalence of ANCA in operated patients was significantly lower than in non-operated UC, suggesting that it might be related either to the presence of inflamed or diseased tissue. ANCA persistence is not related to the surgical procedure and it should not be used as a marker for predicting the development of pouchitis.

Chiral unitary approach to eta'N scattering at low energies

We study the eta'N interaction within a chiral unitary approach which includes piN , etaN and related pseudoscalar meson-baryon coupled channels. Since the SU(3) singlet does not contribute to the standard interaction and the eta' is mostly a singlet, the resulting scattering amplitude is very small and inconsistent with experimental estimations of the eta' N scattering length. The additional consideration of vector meson-baryon states into the coupled channel scheme, via normal and anomalous couplings of pseudoscalar to vector mesons, enhances substantially the eta' N amplitude. We also exploit the freedom of adding to the Lagrangian a new term, allowed by the symmetries of QCD, which couples baryons to the singlet meson of SU(3). Adjusting the unknown strength to the eta' N scattering length, we obtain predictions for the elastic eta'N -> etaN and inelastic eta' N -> etaN , piN , KLambda, KEpsilon cross sections at low eta' energies, and discuss their significance.

Magnetic field effect on quantum corrections to the low-temperature conductivity in mettalic perovskite oxides

The transport and magnetotransport properties of the metallic and ferromagnetic SrRuO3 (SRO) and the metallic and paramagnetic LaNiO3 (LNO) epitaxial thin films have been investigated in fields up to 55 T at temperatures down to 1.8 K . At low temperatures both samples display a well-defined resistivity minimum. We argue that this behavior is due to the increasing relevance of quantum corrections to the conductivity (QCC) as temperature is lowered; this effect being particularly relevant in these oxides due to their short mean free path. However, it is not straightforward to discriminate between contributions of weak localization and renormalization of electron-electron interactions to the QCC through temperature dependence alone. We have taken advantage of the distinct effect of a magnetic field on both mechanisms to demonstrate that in ferromagnetic SRO the weak-localization contribution is suppressed by the large internal field leaving only renormalized electron-electron interactions, whereas in the nonmagnetic LNO thin films the weak-localization term is relevant.

Phenomenological approach to nonlinear Langevin equations

In this paper we address the problem of consistently constructing Langevin equations to describe fluctuations in nonlinear systems. Detailed balance severely restricts the choice of the random force, but we prove that this property, together with the macroscopic knowledge of the system, is not enough to determine all the properties of the random force. If the cause of the fluctuations is weakly coupled to the fluctuating variable, then the statistical properties of the random force can be completely specified. For variables odd under time reversal, microscopic reversibility and weak coupling impose symmetry relations on the variable-dependent Onsager coefficients. We then analyze the fluctuations in two cases: Brownian motion in position space and an asymmetric diode, for which the analysis based in the master equation approach is known. We find that, to the order of validity of the Langevin equation proposed here, the phenomenological theory is in agreement with the results predicted by more microscopic models

Impaired uptake of glutathione by hepatic mitochondria from chronic ethanol-fed rats. Tracer kinetic studies in vitro and in vivo and susceptibility to oxidant stress.

Isolated hepatocytes incubated with [35S]-methionine were examined for the time-dependent accumulation of [35S]-glutathione (GSH) in cytosol and mitochondria, the latter confirmed by density gradient purification. In GSH-depleted and -repleted hepatocytes, the increase of specific activity of mitochondrial GSH lagged behind cytosol, reaching nearly the same specific activity by 1-2 h. However, in hepatocytes from ethanol-fed rats, the rate of increase of total GSH specific radioactivity in mitochondria was markedly suppressed. In in vivo steady-state experiments, the mass transport of GSH from cytosol to mitochondria and vice versa was 18 nmol/min per g liver, indicating that the half-life of mitochondrial GSH was approximately 18 min in controls. The fractional transport rate of GSH from cytosol to mitochondria, but not mitochondria to cytosol, was significantly reduced in the livers of ethanol-fed rats. Thus, ethanol-fed rats exhibit a decreased mitochondrial GSH pool size due to an impaired entry of cytosol GSH into mitochondria. Hepatocytes from ethanol-fed rats exhibited a greater susceptibility to the oxidant stress-induced cell death from tert-butylhydroperoxide. Incubation with glutathione monoethyl ester normalized the mitochondrial GSH and protected against the increased susceptibility to t-butylhydroperoxide, which was directly related to the lowered mitochondrial GSH pool size in ethanol-fed cells.

Anàlisi d'una experiència basada en el mètode de la recerca del medi i amb el suport de les TIC

Avui en dia les Tecnologies de la Informació i la Comunicació (TIC) s’han convertit en eines d’ús quotidià i alhora invisibles en diversos àmbits de la societat i les escoles no n’estan al marge. No cal ensenyar a fer servir eines tecnològiques, sinó que cal entendre-les com un suport. Recerques recents han demostrat que un bon ús d’aquestes potencien un bon ensenyament i aprenentatge. Al mateix temps, es potencien mètodes globalitzats a les aules que permeten construir coneixements significatius a partir de situacions i problemes. Per això, l’objectiu principal d’aquest estudi consisteix en investigar quins canvis s’observen en la motivació de l’alumnat i quins canvis succeeixen a l’aula en general quan s’usen les TIC com a suport en un mètode globalitzat anomenat la recerca del medi. Per tal de resoldre aquest problema d’investigació es recullen diverses dades d’una intervenció didàctica basada en aquest mètode que es porta a terme en dos cursos de cinquè de Primària. Tal com s’observarà, l’ús de les noves tecnologies en un mètode que permet apropar els infants a la realitat n’augmenta la motivació i promou canvis a l’aula que ajuden i faciliten la tasca del docent i alhora afavoreix un aprenentatge significatiu.

Creation and Validation of Chronojump-Boscosystem: A Free Tool to Measure Vertical Jumps

Measuring the height of the vertical jump is an indicator of the strength and power of the lower body. The technological tools available to measure the vertical jump are black boxes and are not open to third-party verification or adaptation. We propose the creation of a measurement system called Chronojump-Boscosystem, consisting of open hardware and free software. Methods: A microcontroller was created and validated using a square wave generator and an oscilloscope. Two types of contact platforms were developed using different materials. These platforms were validated by the minimum pressure required for activation at different points by a strain gauge, together with the on/off time of our platforms in respect of the Ergojump-Boscosystem platform by a sample of 8 subjects performing submaximal jumps with one foot on each platform. Agile methodologies were used to develop and validate the software. Results: All the tools fall under the free software / open hardware guidelines and are, in that sense, free. The microcontroller margin of error is 0.1%. The validity of the fiberglass platform is 0.95 (ICC). The management software contains nearly 113.000 lines of code and is available in 7 languages.

An epidemiological study of dental agenesis in a primary health area in Spain: estimated prevalence and associated factors

Objectives: To evaluate the prevalence of dental agenesis and its possible association with other developmental dental anomalies and systemic entities. Setting and Sample Population: Descriptive transversal study, for which 1518 clinical records, of patients visited by the Odontological Service of the Primary Health Centre of Cassà de la Selva (Girona-Spain) between December 2002 and February 2006 were reviewed. The data were recorded in relation to the oral and dental anomalies and the associated systemic entities, between the ones referred as concomitant in literature. Results: Values of 9.48% (7.25% excluding the third molars) for dental agenesis and 0.39% for oligodontia were obtained. The presence of dental agenesis concomitant with some other forms of oral and dental anomalies was observed. Attention must be drawn to the fact that a greater number of concomitant systemic entities were observed in those patients that presented a severe phenotypical pattern of dental agenesis. Conclusions: The results of the present study do not differ from the ones reported in studies of similar characteristics among Occidental and Spanish populations. The relationship observed between certain systemic entities and developmental dental anomalies suggest a possible common genetic etiology

Beyond the Net Generation debate: A comparison between digital learners in face-to-face and virtual universities

This paper is based on the hypothesis that the use of technology to support learning is not related to whether a student belongs to the Net Generation, but that it is mainly influenced by the teaching model. The study compares behaviour and preferences towards ICT use in two groups of university students: face-to-face students and online students. A questionnaire was applied to asample of students from five universities with different characteristics (one offers online education and four offer face-to-face education with LMS teaching support).

Short communication.Wood identification based on their common name and their transversal surface anatomy. Application to the batch from the expedition of Ruiz and Pavon

Aim of study: To identify species of wood samples based on common names and anatomical analyses of their transversal surfaces (without microscopic preparations). Area of study: Spain and South America Material and methods: The test was carried out on a batch of 15 lumber samples deposited in the Royal Botanical Garden in Madrid, from the expedition by Ruiz and Pavon (1777-1811). The first stage of the methodology is to search and to make a critical analysis of the databases which list common nomenclature along with scientific nomenclature. A geographic filter was then applied to the information resulting from the samples with a more restricted distribution. Finally an anatomical verification was carried out with a pocket microscope with a magnification of x40, equipped with a 50 micrometers resolution scale. Main results: The identification of the wood based exclusively on the common name is not useful due to the high number of alternative possibilities (14 for “naranjo”, 10 for “ébano”, etc.). The common name of one of the samples (“huachapelí mulato”) enabled the geographic origin of the samples to be accurately located to the shipyard area in Guayaquil (Ecuador). Given that Ruiz y Pavon did not travel to Ecuador, the specimens must have been obtained by Tafalla. It was possible to determine correctly 67% of the lumber samples from the batch. In 17% of the cases the methodology did not provide a reliable identification. Research highlights: It was possible to determine correctly 67% of the lumber samples from the batch and their geographic provenance. The identification of the wood based exclusively on the common name is not useful.

A simple model to describe the thixotropic behavior of paints.

We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.

Beyond the net generation debate: A comparison of digital learners in face-to-face and virtual universities

In the last decade, an important debate has arisen about the characteristics of today"s students due to their intensive experience as users of ICT. The main belief is that frequent use of technologies in everyday life implies that competent users are able to transfer their digital skills to learning activities. However, empirical studies developed in different countries reveal similar results suggesting that the"digital native" label does not provide evidence of a better use of technology to support learning. The debate has to go beyond the characteristics of the new generation and focus on the implications of being a learner in a digitalised world. This paper is based on the hypothesis that the use of technology to support learning is not related to whether a student belongs to the Net Generation, but that it is mainly influenced by the teaching model. The study compares behaviour and preferences towards ICT use in two groups of university students: face-to-face students and online students. A questionnaire was applied to a sample of students from five universities with different characteristics (one offers online education and four offer face-to-face education with LMS teaching support). Findings suggest that although access to and use of ICT is widespread, the influence of teaching methodology is very decisive. For academic purposes, students seem to respond to the requirements of their courses, programmes, and universities. There is a clear relationship between students" perception of usefulness regarding certain ICT resources and their teachers" suggested uses of technologies. The most highly rated technologies correspond with those proposed by teachers. The study shows that the educational model (face-to-face or online) has a stronger influence on students" perception of usefulness regarding ICT support for learning than the fact of being a digital native.

Bystander responses to a violent incident in an immersive virtual environment

Under what conditions will a bystander intervene to try to stop a violent attack by one person on another? It is generally believed that the greater the size of the crowd of bystanders, the less the chance that any of them will intervene. A complementary model is that social identity is critical as an explanatory variable. For example, when the bystander shares common social identity with the victim the probability of intervention is enhanced, other things being equal. However, it is generally not possible to study such hypotheses experimentally for practical and ethical reasons. Here we show that an experiment that depicts a violent incident at life-size in immersive virtual reality lends support to the social identity explanation. 40 male supporters of Arsenal Football Club in England were recruited for a two-factor between-groups experiment: the victim was either an Arsenal supporter or not (in-group/out-group), and looked towards the participant for help or not during the confrontation. The response variables were the numbers of verbal and physical interventions by the participant during the violent argument. The number of physical interventions had a significantly greater mean in the ingroup condition compared to the out-group. The more that participants perceived that the Victim was looking to them for help the greater the number of interventions in the in-group but not in the out-group. These results are supported by standard statistical analysis of variance, with more detailed findings obtained by a symbolic regression procedure based on genetic programming. Verbal interventions made during their experience, and analysis of post-experiment interview data suggest that in-group members were more prone to confrontational intervention compared to the out-group who were more prone to make statements to try to diffuse the situation.

Multiple supernumerary teeth not associated with complex syndromes: a retrospective study

Objectives: To determine the epidemiology and describe the clinical and radiographic characteristics, the type of treatment, and the possible delayed appearance of new supernumerary teeth in patients with non-syndromic multiple hyperdontia. Patients and Methods: We conducted a small retrospective observational study of 8 patients diagnosed with nonsyndromic multiple hyperdontia. Multiple hyperdontia not associated to complex syndromes was defined as apparently generally healthy patients with one or more supernumerary teeth in two or more areas. Results: The average patient age was 16.23 years; males predominated (3:1). Multiple hyperodontia with a minimum of 2 and a maximum of 9 supernumerary teeth was found (total: 34 mean: 4.25). The most frequent location was the upper jaw (76.47%). Eumorphic teeth were seen at lower premolar level, while the rest were all heteromorphic. There was altered eruption of the contiguous teeth of 4 of the impacted supernumerary teeth all the rest being asymptomatic. Extraction was the treatment in all patients, and in one of them the delayed appearance of 4 supernumerary teeth was detected. Conclusions: Multiple hyperodontia rarely occurs without being associated with complex syndromes. Prophylactic surgical removal of the supernumerary teeth is generally the treatment of choice.

Mergers and difference-in-difference estimator : why firms do not increase prices?

Difference-in-Difference (DiD) methods are being increasingly used to analyze the impact of mergers on pricing and other market equilibrium outcomes. Using evidence from an exogenous merger between two retail gasoline companies in a specific market in Spain, this paper shows how concentration did not lead to a price increase. In fact, the conjectural variation model concludes that the existence of a collusive agreement before and after the merger accounts for this result, rather than the existence of efficient gains. This result may explain empirical evidence reported in the literature according to which mergers between firms do not have significant effects on prices.