The inverse problem of the calculus of variations and the stabilization of controlled Lagrangian systems

We apply methods of the so-called `inverse problem of the calculus of variations' to the stabilization of an equilibrium of a class of two-dimensional controlled mechanical systems. The class is general enough to include, among others, the inverted pendulum on a cart and the inertia wheel pendulum. By making use of a condition that follows from Douglas' classification, we derive feedback controls for which the control system is variational. We then use the energy of a suitable controlled Lagrangian to provide a stability criterion for the equilibrium

Rental Housing Discrimination and the Persistence of Ethnic Enclaves

We conduct a field experiment to show that discrimination in the rental market represents a significant obstacle for the geographical assimilation process by immigrants. We employ the Internet platform to identify vacant rental apartments in different areas of the two largest Spanish cities, Madrid and Barcelona. We send emails showing interest in the apartments and signal the applicants' ethnicity by using native and foreign-sounding names. We find that, in line with previous studies, immigrants face a differential treatment when trying to rent an apartment. Our results also indicate that this negative treatment varies considerably with the concentration of immigrants in the area. In neighborhoods with a low presence of immigrants the response rate is 30 percentage points lower for immigrants than for natives, while this differential disappears when the immigration share reaches 50%. We conclude that discriminatory practices in the rental housing market contribute to perpetuate the ethnic spatial segregation observed in large cities.immigration, discrimination, spatial segregation

Information and discrimination in the rental housing market: evidence from a field experiment

This paper investigates the effect of disclosing information on the discriminatory behaviour against immigrants in the Spanish rental market. We conduct a field experiment where emails are sent showing interest on vacant rental apartments. Fictitious applicants whose names represent different ethnic groups send emails with different amount of information about their ability to pay the rent. Our results show that applicants with a Moroccan sounding name are 15 percentage points less likely to be contacted by the property owner than those with a Spanish name. We also find that revealing positive information about the socioeconomic status of the Moroccan candidate increases the probability of being contacted by 8 percentage points. However, the information revealed does not completely eliminate discriminatory behavior, suggesting the presence of negative attitudes towards immigrants.Discrimination, migration, rental market, field experiment

Rental housing discrimination and the persistence of ethnic enclaves

We conduct a field experiment to show that discrimination in the rental market represents a significant obstacle for the geographical assimilation process by immigrants. We employ the Internet platform to identify vacant rental apartments in different areas of the two largest Spanish cities, Madrid and Barcelona. We send emails showing interest in the apartments and signal the applicants’ ethnicity by using native and foreign-sounding names. We find that, in line with previous studies, immigrants face a differential treatment when trying to rent an apartment. Our results also indicate that this negative treatment varies considerably with the concentration of immigrants in the area. In neighbourhoods with a low presence of immigrants the response rate is 30 percentage points lower for immigrants than for natives, while this differential disappears when the immigration share reaches 50%. We conclude that discriminatory practices in the rental housing market contribute to perpetuate the ethnic spatial segregation observed in large cities.immigration, discrimination, spatial segregation.

El análisis del discurso como metodología para reconstruir el conocimiento didáctico del contenido

Las investigaciones sobre el CDC se han basado en cuestionarios escritos, entrevistas, técnicas inferenciales, mapas conceptuales, y representaciones pictóricas. Nuestras indagaciones mostraron que esta metodología es especialmente útil para la detección del conocimiento declarativo de los profesores que se manifiesta como ideas explícitas. No obstante, hemos encontrado que los profesores de nivel universitario con menor formación pedagógica que sus pares del secundario, presentan dificultades para expresar y describir lo que hacen durante sus clases y el cómo o el por qué lo hacen. Esto nos llevó a buscar nuevas metodologías para indagar sus concepciones implícitas y sus teorías en uso. En este sentido, el análisis del discurso ha resultado una potente alternativa para aproximarnos al estudio de las prácticas de enseñanza y en particular, para el estudio del CDC

El análisis del discurso como metodología para reconstruir el conocimiento didáctico del contenido

Las investigaciones sobre el CDC se han basado en cuestionarios escritos, entrevistas, técnicas inferenciales, mapas conceptuales, y representaciones pictóricas. Nuestras indagaciones mostraron que esta metodología es especialmente útil para la detección del conocimiento declarativo de los profesores que se manifiesta como ideas explícitas. No obstante, hemos encontrado que los profesores de nivel universitario con menor formación pedagógica que sus pares del secundario, presentan dificultades para expresar y describir lo que hacen durante sus clases y el cómo o el por qué lo hacen. Esto nos llevó a buscar nuevas metodologías para indagar sus concepciones implícitas y sus teorías en uso. En este sentido, el análisis del discurso ha resultado una potente alternativa para aproximarnos al estudio de las prácticas de enseñanza y en particular, para el estudio del CDC

Rental housing discrimination and the persistence of ethnic enclaves

We conduct a field experiment to show that discrimination in the rental market represents a significant obstacle for the residential mobility of immigrants and contributes to the ethnic residential segregation observed in large cities. We employ the Internet platform to identify vacant rental apartments in different areas of the two largest Spanish cities, Madrid and Barcelona. We send emails showing interest in the apartments and signal the applicants’ ethnicity by using native and foreign-sounding names. We find that, in line with previous studies, immigrants face a differential treatment when trying to rent an apartment. Our results also indicate that this negative treatment varies considerably with the share of immigrants in the area. In neighborhoods with a scarce presence of immigrants the response rate is 30 percentage points lower for immigrants than for natives, while this differential decays towards zero as the immigration share increases. This evidence indicates that discriminatory practices may perpetuate the spatial segregation of minority groups.Financial support from Fundación Ramón Areces to the project “Discriminación por raza y género en el mercado español” is gratefully acknowledged. We also acknowledge the IVIE (Instituto Valenciano de Investigaciones Económicas), the Government of Catalonia (Project SGR2014-325) and the Generalitat Valenciana for Grant PROMETEO/2013-037

First record of Oligochoerus limnophilus (Acoela, Acoelomorpha) from British waters

Primer registro de Oligochoerus limnophilus (Acoela, Acoelomorpha) en aguas británicas Informamos de la existencia de poblaciones del acelo Oligochoerus limnophilus (Acoelomorpha) en la islas Británicas sobre la base de los especímenes capturados en el río Támesis (también conocido localmente como río Isis) a su paso por Oxford, Inglaterra, ampliando así considerablemente el área de distribución de la especie, restringida hasta ahora al continente europeo. La información gráfica que aportamos, imágenes de especímenes vivos y proyecciones CLSM de estructuras informativas seleccionadas por su valor sistemático, corrobora su estrecha relación con el género Convoluta Ørsted, 1843.We report the occurrence of the acoel Oligochoerus limnophilus (Acoelomorpha) from the British Islands, based on specimens captured in the river Thames (locally known as the river Isis) in Oxford, England, thereby considerably widening the distributional range of the species that had formerly been reported only from continental Europe. We further present live images and CLSM-projections of systematically informative structures that corroborate a close relationship with the genus Convoluta Ørsted, 1843.Primer registre d'Oligochoerus limnophilus (Acoela, Acoelomorpha) en aigües britàniques Informem de l'existència de poblacions de l'acel Oligochoerus limnophilus (Acoelomorpha) a les illes Britàniques sobre la base dels espècimens capturats al riu Tàmesi (també conegut localment com a riu Isis) al pas per Oxford, Anglaterra, amb la qual cosa ampliem considerablement l'àrea de distribució de l'espècie, restringida fins ara al continent europeu. La informació gràfica que aportem, imatges d'espècimens vius i projeccions CLSM d'estructures informatives seleccionades pel seu valor sistemàtic, corrobora l'estreta relació amb el gènere Convoluta Ørsted, 1843