Nota sobre caràbids (coleoptera) de Catalunya. 1a nota

Es relacionen diverses especies de coleòpters de la família Carabidae, capturats a Catalunya, que els autors consideren de cert interès, tant per ser la primera vegada que es capturen al Principat com perquè les seves captures són sempre rares o esporàdiques en territori català.Note about Carabidae (Coleoptera) of Catalonia. Note 1. Records are given of severa] species of coleoptera of the Carabidae family, collected in Catalonia, which are considered of interest by the authors both because it is the flrst time that they have been collected in the Principat and because their captures are always rare or sporadic in catalan territory

Modeling Premartensitic effects in Ni2MnGa: A Mean Field and Monte Carlo Simulation Study

The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by including both structural and magnetic degrees of freedom in order to elucidate premartensitic effects. Special attention is paied to the effect of the magnetoelastic coupling in Ni2MnGa. The microscopic model is constructed and justified based on the analysis of the experimentally observed strain variables and precursor phenomena. The description includes the (local) tetragonal distortion, the amplitude of the plane-modulating strain, and the magnetization. The model is solved by means of mean-field theory and Monte Carlo simulations. The results show that a variety of premartensitic effects may appear due to the magnetoelastic coupling. For large values of the magnetoelastic coupling parameter we find a premartensitic first-order transition line ending in a critical point. This critical point is responsible for the existence of large premartensitic fluctuations which manifest as broad peaks in the specific heat, not always associated with a true phase transition. The main conclusion is that premartensitic effects result from the interplay between the softness of the anomalous phonon driving the modulation and the magnetoelastic coupling. In particular, the premartensitic transition occurs when such coupling is strong enough to freeze the involved mode phonon.Comment: 28 pages, 15 eps figures, accepted for publication in Phys. Rev.

Naturalistes dels Països Catalans dedicats a l'estudi dels coleòpters

E s presenta una sinopsi sobre els naturalistes dels Països Catalans ja desapareguts i dedicats a l?estudi dels coleòpters. Amb una breu introducció històrica als estudis naturalístics des del segle xvi fins als nostres dies. Un total de 53 notes biogràfiques que corresponen a 6 entomòlegs de la Catalunya del Nord, 29 entomòlegs del principat, 9 entomòlegs del País Valencià i 9 entomòlegs de les Illes Balears. Per a cadascun d?ells es presenta una breu sinopsi biogràfica amb informació sobre les seves coŀleccions i publicacions. S?aporta també una completa bibliografia sobre els naturalistes ressenyats i les imatges de les etiquetes personalitzades de vint autors.A presentation is made on deceased naturalists from the Catalan Countries who were dedicated to the study of coleoptera insects. Within this, a brief historical introduction is given on naturalistic studies made from the 16th century to now. It contains a total of 53 biographical notes corresponding to 6 naturalists from Northern Catalonia, 29 naturalists from the Principality of Catalonia, 9 from the Valencian Country and 9 from the Balearic Islands. A brief biographical note is included containing information relating to collections and publication for each one. A complete bibliography is also included on the reviewed naturalists and the images of insects labels belonging to twenty authors.Se presenta una sinopsis sobre los naturalistas de los Països Catalans ya desaparecidos y dedicados al estudio de los coleópteros. Con una breve introducción histórica a los estudios naturalísticos desde el siglo XVI hasta nuestros días. Se reúnen un total de 53 notas biográficas que corresponden a 6 entomólogos de la Catalunya Nord, 29 entomólogos del principado, 9 entomólogos del País Valenciano y 9 entomólogos de las Islas Baleares. Para cada uno de ellos se presenta una breve sinopsis biográfica con información sobre sus recopilatorios y publicaciones. Se aporta también una completa bibliografía sobre los naturalistas reseñados y las imágenes de las etiquetas personalizadas de veinte autores