Analysis of warm season thunderstorms using an object-oriented tracking method based on radar and total lightning data

Monitoring thunderstorms activity is an essential part of operational weather surveillance given their potential hazards, including lightning, hail, heavy rainfall, strong winds or even tornadoes. This study has two main objectives: firstly, the description of a methodology, based on radar and total lightning data to characterise thunderstorms in real-time; secondly, the application of this methodology to 66 thunderstorms that affected Catalonia (NE Spain) in the summer of 2006. An object-oriented tracking procedure is employed, where different observation data types generate four different types of objects (radar 1-km CAPPI reflectivity composites, radar reflectivity volumetric data, cloud-to-ground lightning data and intra-cloud lightning data). In the framework proposed, these objects are the building blocks of a higher level object, the thunderstorm. The methodology is demonstrated with a dataset of thunderstorms whose main characteristics, along the complete life cycle of the convective structures (development, maturity and dissipation), are described statistically. The development and dissipation stages present similar durations in most cases examined. On the contrary, the duration of the maturity phase is much more variable and related to the thunderstorm intensity, defined here in terms of lightning flash rate. Most of the activity of IC and CG flashes is registered in the maturity stage. In the development stage little CG flashes are observed (2% to 5%), while for the dissipation phase is possible to observe a few more CG flashes (10% to 15%). Additionally, a selection of thunderstorms is used to examine general life cycle patterns, obtained from the analysis of normalized (with respect to thunderstorm total duration and maximum value of variables considered) thunderstorm parameters. Among other findings, the study indicates that the normalized duration of the three stages of thunderstorm life cycle is similar in most thunderstorms, with the longest duration corresponding to the maturity stage (approximately 80% of the total time).

Improving QPF by blending techniques at the Meteorological Service of Catalonia

The current operational very short-term and short-term quantitative precipitation forecast (QPF) at the Meteorological Service of Catalonia (SMC) is made by three different methodologies: Advection of the radar reflectivity field (ADV), Identification, tracking and forecasting of convective structures (CST) and numerical weather prediction (NWP) models using observational data assimilation (radar, satellite, etc.). These precipitation forecasts have different characteristics, lead time and spatial resolutions. The objective of this study is to combine these methods in order to obtain a single and optimized QPF at each lead time. This combination (blending) of the radar forecast (ADV and CST) and precipitation forecast from NWP model is carried out by means of different methodologies according to the prediction horizon. Firstly, in order to take advantage of the rainfall location and intensity from radar observations, a phase correction technique is applied to the NWP output to derive an additional corrected forecast (MCO). To select the best precipitation estimation in the first and second hour (t+1 h and t+2 h), the information from radar advection (ADV) and the corrected outputs from the model (MCO) are mixed by using different weights, which vary dynamically, according to indexes that quantify the quality of these predictions. This procedure has the ability to integrate the skill of rainfall location and patterns that are given by the advection of radar reflectivity field with the capacity of generating new precipitation areas from the NWP models. From the third hour (t+3 h), as radar-based forecasting has generally low skills, only the quantitative precipitation forecast from model is used. This blending of different sources of prediction is verified for different types of episodes (convective, moderately convective and stratiform) to obtain a robust methodology for implementing it in an operational and dynamic way.

Reply to "Comment on 'Nature and entropy content of the ordering transitions in RCo2'"

In the previous Comment, Forker and co-workers claim that perturbed angular correlation (PAC) data leave no alternative to the conclusion that the spontaneous magnetization of PrCo2 and NdCo2 undergoes a discontinuous, first-order phase transition at TC. We show here that their claim is in clear contradiction with a wealth of experimental evidence, including our own. Finally, we propose a possible origin for the disagreement between their interpretation of the PAC results and the literature on this subject.

Resonant spin tunneling in small antiferromagnetic particles

The paper reports a detailed experimental study on magnetic relaxation of natural horse-spleen ferritin. ac susceptibility measurements performed on three samples of different concentration show that dipole-dipole interactions between uncompensated moments play no significant role. Furthermore, the distribution of relaxation times in these samples has been obtained from a scaling of experimental X" data, obtained at different frequencies. The average uncompensated magnetic moment per protein is compatible with a disordered arrangement of atomic spins throughout the core, rather than with surface disorder. The observed field dependence of the blocking temperature suggests that magnetic relaxation is faster at zero field than at intermediate field values. This is confirmed by the fact that the magnetic viscosity peaks at zero field, too. Using the distribution of relaxation times obtained independently, we show that these results cannot be explained in terms of classical relaxation theory. The most plausible explanation of these results is the existence, near zero field, of resonant magnetic tunneling between magnetic states of opposite orientation, which are thermally populated.

Epidemiology of foodborne Norovirus outbreaks in Catalonia, Spain

Background: Noroviruses are one of the principal biological agents associated with the consumption of contaminated food. The objective of this study was to analyse the size and epidemiological characteristics of foodborne outbreaks of gastroenteritis in Catalonia, a region in the northeast of Spain.Methods: In all reported outbreaks of gastroenteritis associated with food consumption, faecal samples of persons affected were analysed for bacteria and viruses and selectively for parasites. Study variables included the setting, the number of people exposed, age, sex, clinical signs and hospital admissions. The study was carried out from October 2004 to October 2005.Results: Of the 181 outbreaks reported during the study period, 72 were caused by Salmonella and 30 by norovirus (NoV); the incidence rates were 14.5 and 9.9 per 100,000 person-years, respectively. In 50% of the NoV outbreaks and 27% of the bacterial outbreaks (p = 0.03) the number of persons affected was ¿10; 66.7% of NoV outbreaks occurred in restaurants; no differences in the attack rates were observed according to the etiology. Hospitalizations were more common (p = 0.03) in bacterial outbreaks (8.6%) than in NoV outbreaks (0.15%). Secondary cases accounted for 4% of cases in NoV outbreaks compared with 0.3% of cases in bacterial outbreaks (p < 0.001)Conclusion: Norovirus outbreaks were larger but less frequent than bacterial outbreaks, suggesting that underreporting is greater for NoV outbreaks. Food handlers should receive training on the transmission of infections in diverse situations. Very strict control measures on handwashing and environmental disinfection should be adopted in closed or partially-closed institutions.

Foodborne norovirus outbreak: the role of an asymptomatic food handler

Background: In July 2005 an outbreak of acute gastroenteritis occurred on a residential summer camp in the province of Barcelona (northeast of Spain). Forty-four people were affected among residents and employees. All of them had in common a meal at lunch time on 13 July (paella, round of beef and fruit). The aim of this study was to investigate a foodborne norovirus outbreak that occurred in the residential summer camp and in which the implication of a food handler was demonstrated by laboratory tests. Methods: A retrospective cohort study was designed. Personal or telephone interview was carried out to collect demographic, clinical and microbiological data of the exposed people, as well as food consumption in the suspected lunch. Food handlers of the mentioned summer camp were interviewed. Ten stool samples were requested from symptomatic exposed residents and the three food handlers that prepared the suspected food. Stools were tested for bacteries and noroviruses. Norovirus was detected using RT-PCR and sequence analysis. Attack rate, relative risks (RR) and its 95% confidence intervals (CI) were calculated to assess the association between food consumption and disease. Results: The global attack rate of the outbreak was 55%. The main symptoms were abdominal pain (90%), nausea (85%), vomiting (70%) and diarrhoea (42.5%). The disease remitted in 24-48 hours. Norovirus was detected in seven faecal samples, one of them was from an asymptomatic food handler who had not eaten the suspected food (round of beef), but cooked and served the lunch. Analysis of the two suspected foods isolated no pathogenic bacteria and detected no viruses. Molecular analysis showed that the viral strain was the same in ill patients and in the asymptomatic food handler (genotype GII.2 Melksham-like). Conclusions: In outbreaks of foodborne disease, the search for viruses in affected patients and all food handlers, even in those that are asymptomatic, is essential. Health education of food handlers with respect to hand washing should be promoted.

Tecnologia i metodologia en l'ensenyament universitari

Aquest article ha estat concebut en dues parts diferenciades, la primera és una aproximació conceptual a l'ús de mitjans en l'ensenyament superior, la segona inclou una analisi crítica de l'ús i de les possibilitats d'aquests mitjans; aquesta analisi es porta a terme des de la perspectiva teórica plantejada anteriorment i amb una dimensió practica i normativa explícita.

Recursos tecnològics i àudio-visuals per a la formació a l'empresa

El director de personal d'una empresa va rebre un informe en que se li suggeria que un important problema de formació podria ser resolt amb l'ajut d'un sistema TEL. Es va plantajar el tema en una reunió de l'equip directiu, pero cap deis assistents no tenia una noció precisa del que significava aixo. Al director de formació li encarregaren d'estudiar la qüestió. Afortunadament, aquells dies se celebraven en una ciutat europea una conferencia i una exhibició sobre TEL, i va decidir d'anar-hi. Després de visitar molts stands, assistir a demostracions i establir diversos contactes, tingué la impressió que era més rellevant la qualitat deis grafics que no pas el contingut de formació; molts deis paquets d'EA0 no eran sinó reculls d'exercicis i molt rarament semblava que s'hi haguessin tingut en compte els principis d'aprenentatge més elementals.

Laboratori de mitjans, estat de la investigació. Grup I més D del Departament de Didàctica i Organització Educativa

M'han sol-licitat una breu presentació del treball que realitzem al grup 1 més 0, que jo coordino. Tractaré de resumir-ne les línies d'investigació en la brevetat de l'espai que m'han destinat. Com que el treball que es presenta és obra de diverses persones, hem inclas les seves adreces electròniques com a referéncies.

La investigación cooperativa

La "Collaborative Research" (Investigación cooperativa) se presenta como una alternativa del diseño "R and D" en Educación y una de las modalidades de la "Action Research". Puede considerarse a E. E. U. U. como país pionero de sus más importantes realizaciones. El artículo intenta presentar una síntesis de la evolución histórica de este tipo de investigación, deteniéndose especialmente en sus orígenes, vinculados a la "Action Research"; la crisis de esta ultima; la creación de los diseños interactivos IR and DT de Tikunoff, Ward y Griffin en 1975 (Interactive Research and Development on teaching) en un contexto internacional favorable al resurgimiento de la Action Research y explicitado en diversidad de corrientes y movimientos orientados a potenciar el cambio educativo y social a través de la investigación; finalmente, su expansión actual. Del estudio de las obras de sus representantes principales (Griffin, Oja, Pine, Smulyan, Tikunoff, Ward, etc. ), se extraen los elementos que podemos considerar claves para una definición de la Collaborative Research, los procesos y diseños de investigación empleados y las condiciones requeridas para que pueda llevarse a cabo. A partir de este análisis se ofrece una reflexión sobre los problemas concretos vinculados a este tipo de investigación: los que surgen al inicio de la misma; los que se dan en torno al proceso de comunicación y, sobre todo los relacionados con la producción real de conocimiento científico, señalando en cada uno de estos apartados posibles vías de soluci6n, apuntadas desde los nuevos enfoques de la investigación educativa. * Profesora Catedrática del Departamento de Métodos de Investigación y Diagnóstico en Educación.

L'educació intercultural. Entre el repte i l'utopia

Este artículo pretende introducir el espacio de reflexión crítica que representa la Tribuna señalando los cuatro interrogantes que guían la aportación de los participantes en ella: ¿Cómo se entiende, desde Cataluña, la educación intercultural? ¿Qué fuerzas la están impulsando? ¿Qué fuerzas la frenan? ¿Cuáles son las debilidades del sistema? ¿Hacia dónde habríamos de dirigir nuestros esfuerzos? En el primer apartado se constata una cierta contradicción entre el discurso teórico de los estudiosos y el discurso de la Administración y el de la propia práctica educativa. En el análisis de los modelos educativos encontrados en las aufas se descubre la tendencia hacia una afirmación hegemónica de la cultura del pa(s de acogida. Entre las fuerzas para impulsar la educación intercultural se encuentra prioritariamente la sensibilidad animada por los estudios, movimientos, organizaciones, cursos y escuelas de verano. También el Programa de Educación Compensatoria, el Programa de Educación en la Diversidad» y la misma actitud de la Administración catalana han favorecido la escolarización de las minorías culturales. E/ Plan Interdepartamental de Inmigración constituye en sr un trabajo para coordinar esluerzos y dar un marco global a las respuestas parciales. Ahora bien, la pobreza de origen de un colectivo de inmigrantes y la existencia de una minoría culturalmente diferenciada han determinado una fuerte asociación entre el hecho de la marginación y el hecho de la diversidad cultural. La asimetría cultural impide una verdadera educación intercultural. Nuestros esfuerzos habrían de dirigirse a crear condiciones para un proyecto educativo intercultural, centrarnos fundamentalmente en la formación del profesorado y en concreto en la revisión de su forma de enseñanza-aprendizaje, estilo de comunicación y tipo de disciplina, esenciales para crear una auténtica educación intercultural.

Cap a una ciutadania intercultural. Un tema emergent a la recerca educativa

En aquest article oferim una aproximació a l'estudi de la ciutadania intercultural des de l'investigació educativa. Per això, hem resumit en primer lloc, els nous plantejaments de la ciutadania que fonamentnen la investigació realitzada pel GREDI en aquests darrers anys. El nostre model recull, com trets claus de la ciutadania que pretenim es desenvolupi des de l'educació, el fet de ser, alhora, activa i responsable, crítica i intercultural; desenvolupada en l'àmbit local però oberta a nivells més amplis. Posteriorment, l'article sintetitza algunes de les investigacions dutes a terme en aquest camp. La segona part d'aquest article ofereix un resum d'una de les investigacions realitzades pel GREDI i que ha permès diagnosticar els elements que configuren el contepcte i la pràctica de la ciutadania en els joves de 14 a 16 anys a Barcelona. Es conclou assenyalant els elements significatius que poden trobar-se en les invesetigacions presentades i que permeten dibuixar les línees de progrés per a qui desitja endinsar-se en la investigació en aquesta àrea temàtica.

Educación multicultural. Líneas de investigación del Grupo de Investigación en Educación Intercultural (GREDI)

El estudio presenta dos investigaciones paralelas. La primera pretende caracterizar el medio familiar de las minorías estudiadas; conocer la percepción del profesorado sobre su práctica educativa en aulas con diferentes minorías culturales; diagnosticar los valores del alumnado de las minorías y conocer su nivel de integración en el aula, por último analizar las actitudes hacia la educación multicultural del profesorado en general. La segunda investigación pretende comprender la diversidad cultural en la escuela; analizar el tratamiento de la realidad multicultural desde la exploración de la vida en el aula: organización del ambiente de aprendizaje; procesos de enseñanza-aprendizaje; estilos de comunicación; relaciones existentes; tipos de disciplina; estimar el nivel de integración de las minorías y descubrir los modelos educativos empleados, dentro y fuera del aula, para abordar la realidad multicultural. A partir de las dos investigaciones se busca identificar las necesidades formativas de los profesores para llevar a cabo una propuesta educativa multicultural.