Magnon-polaron and Spin-polaron Signatures in the Specific Heat and Electrical Resistivity of La0.6Y0.1Ca0.3MnO3La_{0.6}Y_{0.1}Ca_{0.3}MnO_3 in Zero Magnetic Field, and the Effect of Mn−O−MnMn-O-Mn Bond Environment

$La_{0.6}Y_{0.1}Ca_{0.3}MnO_{3}$, an $ABO_{3}$ perovskite manganite oxide, exhibits a non trivial behavior in the vicinity of the sharp peak found in the resistivity $\rho$ as a function of temperature $T$ in zero magnetic field. The various features seen on $d\rho/dT$ are discussed in terms of competing phase transitions. They are related to the $Mn-O-Mn$ bond environment depending on the content of the $A$ crystallographic site. A Ginzburg-Landau type theory is presented for incorporating concurrent phase transitions. The specific heat $C$ of such a compound is also examined from 50 till 200 K. A log-log analysis indicates different regimes. In the low temperature conducting ferromagnetic phase, a collective magnon signature ($C \simeq T^{3/2}$) is found as for what are called magnon-polaron excitations. A $C \simeq T^{2/3}$ law is found at high temperature and discussed in terms of the fractal dimension of the conducting network of the weakly conducting (so-called insulating) phase and Orbach estimate of the excitation spectral behaviors. The need of considering both independent spin scattering and collective spin scattering is thus emphasized. The report indicates a remarkable agreement for the Fisher-Langer formula, i.e. $C$ $\sim$ $d\rho/dT$ at second order phase transitions. Within the Attfield model, we find an inverse square root relationship between the critical temperature(s) and the total local $Mn-O-Mn$ strain.Comment: 19 pages, 5 figures; to be published in Phys Rev

Paleozoic stratigraphy of the Central and Northern part of the Catalonian Coastal Ranges (NE Spain)

The Paleozoic stratigraphic succession in the Catalonian Coastal Ranges spans the interval from Cambrian(?) to Carboniferous, with only one break, separating the pre-Carboniferous part of the sequence from the Carboniferous. The oldest rocks exposed form a sequence of schists, fine grained sandstones, gneisses (laminar pre-Hercynian intrusions), marbles, orto- and para-amphibolites and calcsilicate rocks. comparison with other localities iuggests an Early Cambrian age (or perhaps in part older). Upwards the sequence becomes more monotonous andconsists only of schists (or slates where themetamorphic grade is lower) and thin fine-grained sandstone layers (Cambrian-Ordovician). Still higher in the sequence, an altemation of greywackes and slates is found, with interlayered mud-supported conglomerates at its lower part and acid volcanic rocks which occur throughout the whole sequence. This part of the sequence has provided the oldest faunas known in the Catalonian Coastal Ranges, which indicate the Caradoc. Finally, in its uppermost part, the Ordovician sequence contains some thin limestone layers that contain Ashgill faunas. The Silurian, from Llandovery to Lower Ludlow, consists of black graptolitic shales with dolerite sills, whilst the upper Ludlow, Pridolian and Devonian consist of nodular limestones and marls withpelagic and hemipelagic faunas. The youngest Devonian faunas found correspond in general to the Emsian. The existence of a gap at this point of the sequence suggests the possibility that part of the Devonian could have been eroded. The Carboniferous is characterized by a thick culm sequence (Visean to Westphalian?), resting on thin chert and limestone layers (Tournaisian and Visean). A comparison with neighbouring areas shows a similarity regarding succession and facies with other Paleozoic massifs around the Western Mediterranean

Acció conjunta i desenvolupament d’habilitats sensoriomotores a la sala de psicomotricitat

Aquest treball parteix de la teoria sociocultural de Vygotsky, en què la interacció és clau en el desenvolupament de l’infant. Pretenem analitzar de quina manera infants de tres a quatre anys construeixen el coneixement psicomotor de manera conjunta a partir de l’estudi de la interacció dins del joc sensoriomotor. L’anàlisi de les seqüències d’interacció mostren una gran diversitat d’interaccions entre els infants. D’altra banda, es posa de manifest que el paper de guia del psicomotricista deixa l’espai necessari perquè els infants creïn contextos d’acció propis

Degradation of LaMnO{3-y} surface layer in LaMnO{3-y}/ metal interface

We report electrical measurements showing the degradation processes of LaMnO$_{3-y}$ (LaMnO) in LaMnO/normal metal interface in both point contact and planar-type junctions. Immediately after the preparation of the interface, the degradation process was followed by measuring the evolution of the junction resistance versus time. This process is characterized by the appearance of a second maximum in the resistance vs. temperature (R-T) dependence at temperatures lower than the Curie temperature T$_c$, at which the metal-insulator transition occurs in the bulk. These effects are explained in terms of the formation of a depleted interface layer in LaMnO caused by an out-diffusion of oxygen from the manganite surface to the normal metal. This assumption is confirmed by XPS measurement. Similar results on LaSrMnO$_{3-y}$ interfaces are also obtained.Comment: 4 pages, 3 figures, accepted for publication in Appl. Phys. Lett.(2002

Stem Cells for Modeling Human Disease

Human pluripotent stem cells (PSCs) in the form of human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs) are capable of growing indefinitely in vitro, maintaining their capacity to differentiate into the three primary germ layers: mesoderm, endoderm and ectoderm. Different protocols have been developed to differentiate PSCs into almost any cellular type with different degree of success. This technology has allowed scientists to use patient‐derived iPSCs to study the physiopathology of the disease by analyzing the phenotype of the cells derived from these iPSCs. However, control iPSCs obtained from healthy individuals will always have different genomic environment than patient\u27s iPSCs, making it difficult the interpretation of the cells phenotype. The recent appearance of specific nucleases [zinc‐finger nucleases (ZFNs), the transcription activator‐like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeats (CRISPR)] has made it possible to edit the genome of PSCs. We can now generate syngeneic hESCs or iPSCs harboring the desired mutation and comparing the emerging cells with those derived from genetically identical PSCs that will differ only in the mutated gene. In this chapter, we summarize the progress made in this field and discuss the different approaches that have been used recently for the generation of syngeneic human pluripotent cellular models for different pathologies

Actituds i comportaments dels alumnes davant del treball matemàtic fora de l'aula

En l'article "Treballem la matemàtica fora de l'aula", publicat en el primer número d'aquesta mateixa revista, reflexionàvem sobre la conveniència de fer activitats matemàtiques al carrer. En concret, prevèiem la realització d'un joc de ciutat matemàtic al voltant de la catedral de Tarragona. Després d'haver portat a terme aquesta experiència amb alumnes de 6è, 7è i 8è d'EGB, us oferim la valoració que hem fet de les actituds, comportaments i reaccions d'aquests alumnes durant l'execució d'aquest joc de ciutat i de l'activitat complementària que l'acompanya

Treballem les matemàtiques fora de l’aula

Sovint s’utilitza el material didàctic per reforçar l’ensenyament i aprenentatge del càlcul, de la mesura i de la geometria. També força sovint prenem exemples de la realitat exterior per reforçar l’assimilació d’alguns coneixements. Però això només són models de la realitat. Si la volem presentar als alumnes amb tota la seva globalitat i complexitat, no ens queda cap més remei, ens cal sortir fora de l’aula, fora de l’escola a treballar les matemàtiques

Canalopatías en la epilepsia idiopática monogénica en perros

Epilepsy is a common neurological disorder both dogs and humans. Nevertheless, unlike occurs in humans, in dogs it is a badly characterized disease. In humans, it is known from some time ago, that some idiopathic epilepsies present patterns of mendelian inheritance, i.e., caused by the mutation in single genes. The majority of these mutations are in genes codifying by ion channels, being consider as channelopathies. In dogs, the predisposition of some breeds to suffer the disease has aimed to some research groups to study the hereditary basis of idiopathic epilepsy. This review summarizes some aspects relating to the interest to tackle the study of channelopathies in monogenic idiopathic epilepsy in dogs and shows its potential as future diagnostic or therapeutic targets.La epilepsia es una alteración neurológica común tanto en perros como en personas. Sin embargo, al contrario de lo que ocurre en estos últimos, en los perros es una enfermedad mal caracterizada. En personas, se conoce desde hace tiempo que algunas epilepsias idiopáticas, presentan patrones de herencia mendeliana, es decir, causadas por la mutación en un único gen. La mayoría de estas mutaciones ocurren en genes que codifican para canales iónicos, por lo que son consideradas como canalopatías. En perros, la predisposición de algunas razas a padecer la enfermedad ha animado a algunos grupos de investigación a estudiar los patrones de herencia de la epilepsia idiopática. Esta revisión resume algunos aspectos relativos al interés de abordar el estudio de la implicación de canalopatías en la epilepsia idiomática monogénica en perros y presenta su potencial como futuras dianas tanto de diagnóstico como terapéuticas

Analysis of inter-modulation products and nonlinear distortion in RF OFDM transmitter systems

Postprint (published version