N=2 minimal conformal field theories and matrix bifactorisations of x^d

We establish an action of the representations of N=2-superconformal symmetry on the category of matrix factorisations of the potentials x^d and x^d-y^d for d odd. More precisely we prove a tensor equivalence between (a) the category of Neveu–Schwarz-type representa-tions of the N = 2 minimal super vertex operator algebra at central charge 3–6/d, and (b) a full subcategory of graded matrix factorisations of the potential x^d − y^d . The subcategory in (b) is given by permutation-type matrix factorisations with consecutive index sets. The physical motivation for this result is the Landau–Ginzburg/conformal field theory correspondence, where it amounts to the equivalence of a subset of defects on both sides of the correspondence. Our work builds on results by Brunner and Roggenkamp [BR], where an isomorphism of fusion rules was established

Public Education for the Children Left Behind

This paper examines the role of public education in the context of parental migration, and it studies the effects of an expansive income tax policy that is adopted to increase public education expenditure per pupil. It is shown that such a policy may exacerbate income inequality in the long run if for the less skilled dynasties, the benefits of more public spending on education does not make up for the negative effects of increased parental absences. However, if the migration-induced tax base erosion is not severe, an expansive income tax policy indeed enhances future human capital for all dynasties, and moreover, it may help the less skilled households escape from the poverty trap, thus reducing long-run inequality.Human Capital; Income Inequality; Parental Migration; Public Education Expenditure; Tax Base Erosion

Public Education for the Children Left Behind

This paper examines the role of public education in the context of parental migration, and it studies the effects of an expansive income tax policy that is adopted to increase public education expenditure per pupil. It is shown that such a policy may exacerbate income inequality in the long run if for the less skilled dynasties, the benefits of more public spending on education does not make up for the negative effects of increased parental absences. However, if the migration-induced tax base erosion is not severe, an expansive income tax policy indeed enhances future human capital for all dynasties, and moreover, it may help the less skilled households escape from the poverty trap, thus reducing long-run income inequality.human capital, income inequality, parental migration, public education expenditure, tax base erosion

Second-harmonic generation of ZnO nanoparticles synthesized by laser ablation of solids in liquids

We report the synthesis of small zinc oxide nanoparticles (ZnO NPs) based colloidal suspensions and the study of second-harmonic generation from aggregated ZnO NPs deposited on glass substrates. The colloidal suspensions were obtained using the laser ablation of solids in liquids technique, ablating a Zn solid target immersed in acetone as the liquid medium, with ns-laser pulses (1064 nm) of a Nd-YAG laser. The per pulse laser fluence, the laser repetition rate frequency and the ablation time were kept constant. The absorption evolution of the obtained suspensions was optically characterized through absorption spectroscopy until stabilization. Raman spectroscopy, SEM and HRTEM were used to provide evidence of the ZnO NPs structure. HRTEM results showed that 5–8 nm spheroids ZnO NPs were obtained. Strong second-harmonic signal is obtained from random ZnO monocrystalline NPs and from aggregated ZnO NPs, suggesting that the high efficiency of the nonlinear process may not depend on the NPs size or aggregation state

OB stars at the lowest Local Group metallicity: GTC-OSIRIS observations of Sextans A

Our aim is to find and classify OB stars in Sextans A, to later determine accurate stellar parameters of these blue massive stars in this low metallicity region $(Z \sim 0.1 \rm Z_{\odot})$. Using UBV photometry, the reddening-free index Q and GALEX imaging, we built a list of blue massive star candidates in Sextans A. We obtained low resolution (R $\sim$ 1000) GTC-OSIRIS spectra for a fraction of them and carried out spectral classification. For the confirmed O-stars we derive preliminary stellar parameters. The target selection criteria and observations were successful and have produced the first spectroscopic atlas of OB-type stars in Sextans A. From the whole sample of 18 observed stars, 12 were classified as early OB-types, including 5 O-stars. The radial velocities of all target stars are in agreement with their Sextans A membership, although three of them show significant deviations. We determined the stellar parameters of the O-type stars using the stellar atmosphere code FASTWIND, and revisited the sub-SMC temperature scale. Two of the O-stars are consistent with relatively strong winds and enhanced helium abundances, although results are not conclusive. We discuss the position of the OB stars in the HRD. Initial stellar masses run from slightly below 20 up to 40 solar masses. The target selection method worked well for Sextans A, confirming the procedure developed in Garcia \& Herrero (2013). The stellar temperatures are consistent with findings in other galaxies. Some of the targets deserve follow-up spectroscopy because of indications of a runaway nature, an enhanced helium abundance or a relatively strong wind. We observe a correlation between HI and OB associations similar to the irregular galaxy IC1613, confirming the previous result that the most recent star formation of Sextans A is currently on-going near the rim of the H\,{\sc I} cavity

Distribución de la familia Parabathynellidae (Crustacea, Syncarida, Bathynellacea) en la Península Ibérica e Islas Baleares

This paper reviews all the knowledge on the presence and distribution of 26 species of the family Parabathynellidae Noodt, 1964 (Crustacea, Syncarida, Bathynellacea) on the Iberian Peninsula and Balearic Islands. The different genera, subgenera and species distributions are subjected to a basic analysis. The presence of these taxa in different subterranean aquatic habitats (caves, springs, wells and interstitial environment) is also discussed. The most sampled habitat was the interstitial environment (45%); the least sampled habitat was springs (5%). The most commonly found genus was Iberobathynella Schminke, 1973 (54%) and the rarest was Guadalopebathynella Camacho & Serban, 1998 (0.7%) All the knowledge on these taxa in the study area, in Europe and in the world is compared and evaluated. More species of the Parabathynellidae live on the Iberian Peninsula and Balearic Islands than in any other part of the world (26 species). Iberobathynella is a highly diversified genus endemic to the Iberian peninsula. Its diversity is comparable to another genus in the order, Hexabathynella Schminke, 1972, which also has 18 described species. However, Hexabathynella has a cosmopolitan distribution.En este trabajo se reúne y actualiza el conocimiento acerca de la presencia y distribución de 26 especies de batinelas de la familia Parabathynellidae (Crustacea, Syncarida, Bathynellacea) en la Península Ibérica y las Islas Baleares. Se analiza de forma crítica la distribución de los diferentes géneros, subgéneros y especies y se discute acerca de la presencia de los mismos en diferentes habitat acuáticos subterráneos (cuevas, fuentes o surgencias, pozos y medio intersticial asociado a ríos epigeos). El mayor número de puntos de muestreo corresponde al medio intersticial (45% del total) y en él se encuentran los cinco géneros presentes en el área de estudio; las surgencias constituyen el conjunto con menos puntos de muestreo (5%) y en ellas sólo se encuentran los géneros Iberobathynella (86%) y Hexaiberobathynella Camacho & Serban, 1998 (14%). El género Iberobathynella es el más común (54% de las muestras) y vive en todos los medios. El género Guadalopebathynella sólo se ha encontrado en el medio intersticial de un río. Se valora comparativamente el conocimiento de estos taxa en el área estudiada, en Europa y en el mundo. En la Península Ibérica y las Islas Baleares vive el mayor porcentaje de especies de todo el mundo (24%) y todas ellas son endémicas de esta zona. El género Iberobathynella, endémico de la Península Ibérica, cuenta con 18 especies conocidas y tal diversificación sólo se da, en todo el orden, dentro del género Hexabathynella (18 especies) que es el único género cosmopolita de Bathynellacea

Una pieza más de un género puzzle: una nueva especie de Iberobathynella Schminke, 1973 (Syncarida, Bathynellacea, Parabathynellidae) en la Península Ibérica

A new Iberian species of the genus Iberobathynella is described from the groundwater of Ojo Guareña cave, in the north of Spain (Burgos). The new species belongs to the subgenus Espanobathynella and presents a unique combination of characters, as follow: female thoracopod 8 with wrinkled cuticle and 1 tooth (the rest of species in this subgenus show a smooth cuticle); seven-eight spines on the furca; 10-12 spines on the sympod, four barbed setae on the exopod and an unarmed endopod of the uropod; labrum with 9 main teeth in the female and 8 in the male; maxilla with one, four and 15 setae on its three segments, respectively; seven teeth on the distal segment of the maxillule; seven teeth on the pars incisive and seven-nine teeth on the pars molaris of the mandible and antennule with 7 segments.Se describe una nueva especie del género Iberobathynella (consta de 21 especies endémicas de la Península Ibérica) encontrada en la cueva más grande de España, Ojo Guareña (Burgos). La nueva especie pertenece al subgénero Iberobathynella (Espanobathynella) compuesto por 4 especies, contando ésta. Este subgénero sólo se había encontrado hasta la fecha en 2 áreas muy pequeñas de Asturias y Cantabria, y siempre en agua subterránea de cuevas. La nueva especie presenta una combinación de caracteres única: el pereiopodo 8 de la hembra tiene la cutícula rugosa (el resto de especies del subgénero la tiene lisa) y una sola fanera; tiene 7-8 espinas en la furca; el simpodio del urópodo consta de 10-12 espinas, tiene 4 sedas ciliadas en el exopodio y carece de sedas en el endopodio; el labro con 9 dientes principales en la hembra y 8 en el macho (número habitual en el género); la maxila tiene 1, 4 y 15 sedas, respectivamente, en sus 3 segmentos; la maxílula consta de 7 dientes en el segmento distal; la mandíbula tiene 7 dientes en la pars incisiva y entre 7 y 9 en la pars molaris, y la anténula tiene 7 segmentos

An Overview of the Distribution of the Parabathynellidae (Crustacea, Syncarida Bathynellacea) on the Iberian Peninsula and Balearic Islands

[EN] This paper reviews all the knowledge on the presence and distribution of 26 species of the family Parabathynellidae Noodt, 1964 (Crustacea, Syncarida, Bathynellacea) on the Iberian Peninsula and Balearic Islands. The different genera, subgenera and species distributions are subjected to a basic analysis. The presence of these taxa in different subterranean aquatic habitats (caves, springs, wells and interstitial environment) is also discussed. The most sampled habitat was the interstitial environment (45%); the least sampled habitat was springs (5%). The most commonly found genus was Iberobathynella Schminke, 1973 (54%) and the rarest was Guadalopebathynella Camacho & Serban, 1998 (0.7%) All the knowledge on these taxa in the study area, in Europe and in the world is compared and evaluated. More species of the Parabathynellidae live on the Iberian Peninsula and Balearic Islands than in any other part of the world (26 species). Iberobathynella is a highly diversified genus endemic to the Iberian peninsula. Its diversity is comparable to another genus in the order, Hexabathynella Schminke, 1972, which also has 18 described species. However, Hexabathynella has a cosmopolitan distribution.[ES] En este trabajo se reune y actualiza el conocimiento acerca de la presencia y distribución de 26 especies de batinelas de la familia Parabathynellidae (Crustacea, Syncarida, Bathynellacea) en la Peninsula Ibérica y las Islas Baleares. Se analiza de forma crítica la distribución de los diferentes géneros, subgéneros y especies y se discute acerca de la presencia de los mismos en diferentes habitat acuáticos subterráneos (cuevas, fuentes o surgencias, pozos y medio intersticial asociado a ríos epigeos). El mayor número de puntos de muestreo corresponde al medio intersticial (45% del total) y en él se encuentran los cinco géneros presentes en el área de estudio; las surgencias constituyen el conjunto con menos puntos de muestreo (5%) y en ellas solo se encuentran los géneros Iberobathynella (86%) y Hexaiberobathynella Camacho & Serban, 1998 (14%). El género Iberobathynella es el más común (54% de las muestras) y vive en todos los medios. El género Guadalopebathynella sólo se ha encontrado en el medio intersticial de un río. Se valora comparativamente el conocimiento de estos taxa en el área estudiada, en Europa y en el mundo. En la Península Ibérica y las Islas Baleares vive el mayor porcentaje de especies de todo el mundo (24%) y todas ellas son endémicas de esta zona. El género Iberobathynella, endémico de la Península Ibérica, cuenta con 18 especies conocidas y tal diversificación sólo se da, en todo el orden, dentro del género Hexabathynella (18 especies) que es el único género cosmopolita de Bathynellacea.This work was supported by projects REN2000-2040 GLO, EVK2-CT-2001- 00121 (PASCALIS) and Convenio Junta de Castilla y León- CSIC (2002-2004).Peer reviewe