Chaotic, memory, and cooling rate effects in spin glasses: Evaluation of the Edwards-Anderson model

We investigate chaotic, memory, and cooling rate effects in the three-dimensional Edwards-Anderson model by doing thermoremanent (TRM) and ac susceptibility numerical experiments and making a detailed comparison with laboratory experiments on spin glasses. In contrast to the experiments, the Edwards-Anderson model does not show any trace of reinitialization processes in temperature change experiments (TRM or ac). A detailed comparison with ac relaxation experiments in the presence of dc magnetic field or coupling distribution perturbations reveals that the absence of chaotic effects in the Edwards-Anderson model is a consequence of the presence of strong cooling rate effects. We discuss possible solutions to this discrepancy, in particular the smallness of the time scales reached in numerical experiments, but we also question the validity of the Edwards-Anderson model to reproduce the experimental results.

Investigating independent language learning in classroom-based EFL Learners

La recerca efectuada sobre les estratègies d’aprenentatge de llengües ha demostrat que els aprenents que utilitzen estratègies metacognitives (planificació, revisió i avaluació) desenvolupen estratègies cognitives més eficaces (Anderson, 2002). Aquest article descriu les activitats que 43 estudiants de llengua estrangera de la Universitat de Vic van emprendre de forma independent i dedueix les estratègies metacognitives que van utilitzar sense cap formació prèvia en estratègies. Els estudiants van completar un dossier on expressaven les necessitats d’aprenentatge, la planificació i supervisió de les activitats i finalment l’avaluació de l’aprenentatge que havien portat a terme de manera independent fora de les hores lectives. La primera fase de l’anàlisi de les dades revela que, tot i que els estudiants foren capaços d’expressar les necessitats d’aprenentatge en general, la formulació d’objectius i la supervisió de les activitats fou escassa. La discussió gira entorn de la formació dels estudiants de llengües estrangeres en estratègies metacognitives i la integració de l’aprenentatge autònom dins el currículum docent.

Urban spatial structure and suburbanisation. The case of the Barcelona Metropolitan

The metropolitan spatial structure displays various patterns, sometimes monocentricity and sometimes multicentricity, which seems much more complicated than the exponential density function used in classic works such as Clark (1961), Muth (1969) or Mills (1973) among others, can effectively represent. It seems that a more flexible density function,such as cubic spline function (Anderson (1982), Zheng (1991), etc.) to describe the density-accessibility relationship is needed. Also, accessibility, the fundamental determinant of density variations, is only partly captured by the inclusion of distance to the city centre as an explanatory variable. Steen (1986) has proposed to correct that miss-especification by including an additional gradient for distance to the nearest transportation axis. In identifying the determinants of urban spatial structure in the context of inter-urban systems, some of the variables proposed by Muth (1969), Mills (1973) and Alperovich (1983) such as city age or population, make no sense in the case of a single urban system. All three criticism to the exponential density function and its determinants apply for the Barcelona Metropolitan Region, a polycentric conurbation structured on well defined transportation axes.

La historiografia de la malaltia durant el segle XX

Fins a ben endins la dècada de 1920 la idea de que les malalties són entitats naturals essencialment contínues en l’espai i el temps —i, com a màxim, susceptibles en el cas de les afeccions infeccioses, d’experimentar canvis explicables per les lleis bioevolutives que regulen les relacions entre els diferents éssers vius— fou incontestable entre els historiadors de la malaltia, en gran manera en raó del paper “disciplinari” i, abans de res, legitimador de la ciència mèdica moderna, que la història de la medicina havia jugat des de la seva institucionalització a finals del segle XIX. Aquesta nota repassa la historiografia del segle XX sobre la malaltia humana des de la història de la medicina. Se n’examinen sucessivament: la “perspectiva bacteriològica”, la influència de la història cultural i social, i l’impacte del socioconstructivisme. A la fi, se n’apunten les propostes més recents des del “gir lingüístic” i el postrelativisme.

La concepció evolucionista de la natura en el programa de difusió de la cultura cientí­fica d'Antoni Bergnes de las Casas (1801-1879)

La recerca es centra en l'™obra de divulgació cientí­fica d'™Antoni Bergnes de las Casas al llarg del segle XIX a Barcelona. En les obres i revistes que publicà destaca la difusió de noves concepcions en la història natural. En elles es divulga la teoria evolucionista de Lamarck i d'altres models evolutius similars, però que defensen la intervenció divina en el procés. Aquests fets posen de manifest la presència de teories evolutives a Catalunya i a Espanya en la primera meitat del segle XIX, i de la teoria evolucionista de Lamarck a principi dels anys seixanta del segle.

El dret civil català davant la transposició de la directiva 2008/112, relativa a certs aspectes contractuals de l’aprofitament per torns de béns mobles i immobles

L’objectiu principal d’aquest estudi consisteix a determinar quines implicacions té en l’ordenament jurídic civil català l’aprovació de la Directiva 2008/122, del Parlament Europeu i del Consell, 14.1.2009, relativa a la protecció dels consumidors respecte a determinats aspectes dels contractes d’aprofitament per torn de béns d’ús turístic, d’adquisició de productes de vacances de llarga durada, de revenda i d’intercanvi.

Revisió dels resultats de les fractures diafisàries de tíbia

Estudi d’avaluació dels resultats del tractament de fractures diafisàries de tíbia mitjançant la tècnica quirúrgica d’enclavat endomedul•lar fresat i bloquejat, amb un seguiment mig de 14 mesos. Els criteris d’inclusió han estat les fractures tancades i obertes, segons la Classificació de la AO i la Classificació de Gustilo-Anderson per les fractures obertes, excloent fractures amb traç articular o afectació metafisària. Es tracta d’un estudi retrospectiu de totes les històries clíniques, realitzant una valoració radiològica pre i postquirúrgica. Posteriorment s’ha realitzat una valoració clínica mitjançant l’escala de Karlström i Olerud. Finalment, s’ha dut a terme una revisió actualitzada de la literatura.

Towards closure between measured and modelled UV under clear skies at four diverse sites

The purpose of this work is determine the extent of closure between measurements and models of UV irradiances at diverse sites using state of the art instruments, models, and the best available data as inputs to the models. These include information about aerosol optical depth (unfortunately not extending down as far into the UVB region as desirable because such information is not generally available), ozone column amounts, as well as vertical profiles of temperature. We concentrate on clear-sky irradiances, and report the results in terms of UV Index (UVI)

"El Precio de la muerte" : anàlisi del mercat funerari a la ciutat de Barcelona

Heu contractat alguna vegada un servei funerari? Encara que la resposta de molts de nosaltres és que no, és ben segur que algun cop en la nostra vida ho haurem de fer i potser és millor pensar quin tipus de servei estarem contractant abans que arribi el moment de fer-ho. “El precio de la muerte” és un treball on s’ha fet un anàlisi del mercat funerari a Barcelona i la seva utilitat rau en el fet de que aquest tipus de serveis, encara avui dia, segueix sent molt desconegut i és per això que aquí donarem respostes a les principals preguntes que pugui tenir el lector. Si voleu saber en qui recau la responsabilitat d’oferir aquest servei, com es fixen els preus o qui es queda els 10 milions d’euros que dona de benefici una empresa d’aquest tipus no dubteu en llegir aquest treball, i aquesta i moltes preguntes més trobaran resposta.Finalment, ens plau pensar que l’esforç de reunir aquesta informació serveixi als consumidors per afrontar un tràmit tan forçós des d’una posició d’igualtat davant l’empresa oferidora, i evitar així preus abusius i serveis innecessaris.

Flexibility vs. rigidity: Does Spain have the worst of both worlds?

In this paper we study the structure of labor market flows in Spain and compare them with France and the US. We characterize a number of empirical regularities and stylized facts. One striking result is that the job finding rate is slightly higher than in France, while the jon loss rate is much higher, putting Spain half-way between France and the US. This suggests that while Spain has borne the full cost of its labor market reforms in terms of job precarity, the benefits in terms of job creation have been quite modest. We hypothesize that this has been due to the reform s credibility being imperfect, which leads toexpectation of reversal.

Nitrogen incorporation effects in Fe(001) thin films

Nitrogen incorporates into Fe thin films during reactively sputtered TiN capping layer deposition. The influence that this nitrogen incorporation has both on the structure and magnetic properties is discussed for a series of Fe~001! thin films grown at different temperatures. A higher nitrogen content is accompanied by distortion in the Fe lattice and by reduction in the Fe magnetization saturation as well as in the effective anisotropy constant, K. The reduction of K brings as a consequence lowering in the coercive field with respect to equivalent Fe films with no nitrogen present.

Growth and magnetic properties of multiferroic LaxBi1-xMnO3 thin films

A comparative study of LaxBi1-xMnO3 thin films grown on SrTiO3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of LaxBi1-xMnO3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions.

Continuous phase transition in a spin-glass model without time-reversal symmetry

We investigate the phase transition in a strongly disordered short-range three-spin interaction model characterized by the absence of time-reversal symmetry in the Hamiltonian. In the mean-field limit the model is well described by the Adam-Gibbs-DiMarzio scenario for the glass transition; however, in the short-range case this picture turns out to be modified. The model presents a finite temperature continuous phase transition characterized by a divergent spin-glass susceptibility and a negative specific-heat exponent. We expect the nature of the transition in this three-spin model to be the same as the transition in the Edwards-Anderson model in a magnetic field, with the advantage that the strong crossover effects present in the latter case are absent.

The non-LTR retrotransposons in Ciona intestinalis: new insights into the evolution of chordate genomes

Background: Non-long terminal repeat (non-LTR) retrotransposons have contributed to shaping the structure and function of genomes. In silico and experimental approaches have been used to identify the non-LTR elements of the urochordate Ciona intestinalis. Knowledge of the types and abundance of non-LTR elements in urochordates is a key step in understanding their contribution to the structure and function of vertebrate genomes. Results: Consensus elements phylogenetically related to the I, LINE1, LINE2, LOA and R2 elements of the 14 eukaryotic non-LTR clades are described from C. intestinalis. The ascidian elements showed conservation of both the reverse transcriptase coding sequence and the overall structural organization seen in each clade. The apurinic/apyrimidinic endonuclease and nucleic-acid-binding domains encoded upstream of the reverse transcriptase, and the RNase H and the restriction enzyme-like endonuclease motifs encoded downstream of the reverse transcriptase were identified in the corresponding Ciona families. Conclusions: The genome of C. intestinalis harbors representatives of at least five clades of non-LTR retrotransposons. The copy number per haploid genome of each element is low, less than 100, far below the values reported for vertebrate counterparts but within the range for protostomes. Genomic and sequence analysis shows that the ascidian non-LTR elements are unmethylated and flanked by genomic segments with a gene density lower than average for the genome. The analysis provides valuable data for understanding the evolution of early chordate genomes and enlarges the view on the distribution of the non-LTR retrotransposons in eukaryotes.

Heparin attenuates TNF-alpha induced inflammatory response through a CD11b dependent mechanism

Background In addition to its anticoagulant properties, heparin has anti-inflammatory effects, the molecular and mechanistic bases of which are incompletely defined. AIMS The current studies were designed to test the hypothesis that heparin abrogates the expression or function of leucocyte-endothelial adherence molecules which are fundamental to the acute inflammatory response. Methods The effects of heparin on tumour necrosis factor alpha (TNF-¿) induced leucocyte rolling, adhesion, and migration as well as vascular permeability were assessed in rat mesenteric venules using intravital microscopy. Expression of adhesion molecules was quantitated using a double radiolabelled monoclonal antibody (mAb) binding technique in vivo (P-selectin, intercellular cell adhesion molecule type 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1)) or flow cytometry (CD11a, CD11b, and L-selectin). Ex vivo binding of heparin to neutrophils was assessed by flow cytometry. RESULTS TNF-alpha induced a significant increase in leucocyte rolling, adhesion, and migration, and vascular permeability, coincident with a significant increase in expression of P-selectin, ICAM-1, and VCAM-1. Ex vivo assessment of blood neutrophils showed significant upregulation of CD11a and CD11b and significant downregulation of L-selectin within five hours of TNF-¿ administration. Heparin pretreatment significantly attenuated leucocyte rolling, adhesion, and migration but did not affect expression of cell adhesion molecules or vascular permeability elicited by TNF-¿ administration. Binding of heparin was significantly increased on blood neutrophils obtained five hours after TNF-¿ administration. Preincubation with an anti-CD11b mAb but not with an anti-CD11a or anti-L-selectin antibody significantly diminished heparin binding ex vivo.