Cosmological perturbations from stochastic gravity

In inflationary cosmological models driven by an inflaton field the origin of the primordial inhomogeneities which are responsible for large-scale structure formation are the quantum fluctuations of the inflaton field. These are usually calculated using the standard theory of cosmological perturbations, where both the gravitational and the inflaton fields are linearly perturbed and quantized. The correlation functions for the primordial metric fluctuations and their power spectrum are then computed. Here we introduce an alternative procedure for calculating the metric correlations based on the Einstein-Langevin equation which emerges in the framework of stochastic semiclassical gravity. We show that the correlation functions for the metric perturbations that follow from the Einstein-Langevin formalism coincide with those obtained with the usual quantization procedures when the scalar field perturbations are linearized. This method is explicitly applied to a simple model of chaotic inflation consisting of a Robertson-Walker background, which undergoes a quasi-de Sitter expansion, minimally coupled to a free massive quantum scalar field. The technique based on the Einstein-Langevin equation can, however, deal naturally with the perturbations of the scalar field even beyond the linear approximation, as is actually required in inflationary models which are not driven by an inflaton field, such as Starobinsky¿s trace-anomaly driven inflation or when calculating corrections due to nonlinear quantum effects in the usual inflaton driven models.

Mossbauer studies of amorphous FeSi compositionally modulated thin films

Conversion electron Mossbauer spectra of composition modulated FeSi thin films have been analysed within the framework of a quasi shape independent model in which the distribution function for the hyperfine fields is assumed to be given by a binomial distribution. Both the hyperfine field and the hyperfine field distribution depend on the modulation characteristic length.

Analytic behavior of the QED polarizability function at finite temperature

We revisit the analytical properties of the static quasi-photon polarizability function for an electron gas at finite temperature, in connection with the existence of Friedel oscillations in the potential created by an impurity. In contrast with the zero temperature case, where the polarizability is an analytical function, except for the two branch cuts which are responsible for Friedel oscillations, at finite temperature the corresponding function is non analytical, in spite of becoming continuous everywhere on the complex plane. This effect produces, as a result, the survival of the oscillatory behavior of the potential. We calculate the potential at large distances, and relate the calculation to the non-analytical properties of the polarizability.

Max-convex decompositions for cooperative TU games

We show that any cooperative TU game is the maximum of a finite collection of convex games. This max-convex decomposition can be refined by using convex games with non-negative dividends for all coalitions of at least two players. As a consequence of the above results we show that the class of modular games is a set of generators of the distributive lattice of all cooperative TU games. Finally, we characterize zero-monotonic games using a strong max-convex decomposition

Growth rate of fractal copper electrodeposits: Potential and concentration effects

Experiments are reported on fractal copper electrodeposits. An electrochemical cell was designed in order to obtain a potentiostatic control on the quasi-two-dimensional electrodeposition process. The aim was focused on the analysis of the growth rate of the electrodeposited phase, in particular its dependence on the electrode potential and electrolyte concentration.

Nanomechanical properties of molecular organic thin films

Using atomic force microscopy we have studied the nanomechanical response to nanoindentations of surfaces of highly oriented molecular organic thin films (thickness¿1000¿nm). The Young¿s modulus E can be estimated from the elastic deformation using Hertzian mechanics. For the quasi-one-dimensional metal tetrathiafulvalene tetracyanoquinodimethane E~20¿GPa and for the ¿ phase of the p-nitrophenyl nitronyl nitroxide radical E~2GPa. Above a few GPa, the surfaces deform plastically as evidenced by discrete discontinuities in the indentation curves associated to molecular layers being expelled by the penetrating tip.

Dynamics of transient pattern formation in nematic liquid crystals

We analyze the dynamics of a transient pattern formation in the Fréedericksz transition corresponding to a twist geometry. We present a calculation of the time-dependent structure factor based on a dynamical model which incorporates consistently the coupling of the director field with the velocity flow and also the effect of fluctuations. The appearance and development of a characteristic periodicity is described in terms of the time dependence of the maximum of the structure factor. We find a well-defined time for the appearance of the pattern and a subsequent stage of pattern development in which the characteristic periodicity tends to an asymptotic value.

Ab Initio study of magnetic interactions in the KCuF3 and K2CuF4 low-dimensional Systems

The ab initio cluster model approach has been used to study the electronic structure and magnetic coupling of KCuF3 and K2CuF4 in their various ordered polytype crystal forms. Due to a cooperative Jahn-Teller distortion these systems exhibit strong anisotropies. In particular, the magnetic properties strongly differ from those of isomorphic compounds. Hence, KCuF3 is a quasi-one-dimensional (1D) nearest neighbor Heisenberg antiferromagnet whereas K2CuF4 is the only ferromagnet among the K2MF4 series of compounds (M=Mn, Fe, Co, Ni, and Cu) behaving all as quasi-2D nearest neighbor Heisenberg systems. Different ab initio techniques are used to explore the magnetic coupling in these systems. All methods, including unrestricted Hartree-Fock, are able to explain the magnetic ordering. However, quantitative agreement with experiment is reached only when using a state-of-the-art configuration interaction approach. Finally, an analysis of the dependence of the magnetic coupling constant with respect to distortion parameters is presented.

Dynamics of transient domain structures in nematic liquid crystals: The splay Fréedericksz transition

We discuss the dynamics of the transient pattern formation process corresponding to the splay Fréedericksz transition. The emergence and subsequent evolution of the spatial periodicity is here described in terms of the temporal dependence of the wave numbers corresponding to the maxima of the structure factor. Situations of perpendicular as well as oblique field-induced stripes relative to the initial orientation of the director are both examined with explicit indications of the time scales needed for their appearance and posterior development.

Dones migrants al servei domèstic: conciliació de la vida de les conciliadores

Actualment el flux migratori internacional s"ha feminitzat, quasi la meitat és compost per dones. No obstant això, malgrat exercir una influència en el comportament i en els projectes migratoris, la variable de gènere habitualment no ha estat recollida com a variable específica. L"article posa atenció en el col·lectiu de treballadores de la llar atesa la poca visibilitat que tenen en el debat públic. Al mateix temps, ha d"assumir un triple risc d"exclusió social (dones, migrants i amb precarietat laboral). Aquest col·lectiu ha estat un suport important per a moltes famílies europees en permetre a la dona, que continua assumint amb major grau la responsabilitat de la llar, conciliar la vida familiar i professional. Les qüestions clau sobre les quals reflexionarem són les possibilitats de conciliació que tenen les mateixes «reconciliadores », i també les oportunitats de participació i, per tant, d"integració a la societat d"acollida. El sector econòmic no afavoreix l"accés a aquests dos processos atès que l"accés a drets laborals és desigual i també hi ha una part important de situacions dins l"economia submergida. Aquesta realitat no ha estat abordada en profunditat dins del debat públic. Són els moviments de dones dins del marc del feminisme dialògic els que estan formulant estratègies més efectives i equitatives d"inclusió social i d"igualtat d"oportunitats. Paraules clau: gènere, immigració, conciliació, inclusió.

Guia Managgend: Indicadors de gestió i de gènere per a la competitivitat i creixement dels sectors públic i privat de Catalunya en una societat del coneixement complexa.

L'actual crisi econòmica, del model de producció i les greus conseqüències que està tenint en el teixit industrial, productiu, econòmic, de consum, de diferents sectors, així com la pèrdua de competitivitat i el descens de la nostra productivitat com quasi la més baixa d'Europa, ens porta a cercar solucions i alternatives en la gestió empresarial i a la direcció de les organitzacions públiques i privades,com un dels factors estratègics que podrien ajudar a col·laborar a la sortida de la crisi.

El desplegament curricular de les competències bàsiques. Una proposta real d’intervenció

Les competències bàsiques han entrat a formar part dels currículums del país per donar resposta a les finalitats educatives que s'han descrit en l'àmbit internacional per definir les capacitats i els sabers que s'han d'haver adquirit al final de l'educació secundària obligatòria. A més dels tradicionals continguts relacionats amb les disciplines del saber, els canvis socials i culturals que estem vivim, les noves relacions personals i la complexitat en l'àmbit laboral han provocat que el currículum inclogui altres continguts relacionats amb la formació integral de la persona mitjançant les competències metadisciplinàries. El fet d'introduir les competències bàsiques en un currículum organitzat per àrees i amb una descripció quasi nul·la dels objectius i continguts de cada competència n'ha dificultat molt la comprensió i la posada en pràctica. Actuar de manera competent vol dir saber resoldre amb èxit un problema o una qüestió de la realitat a partir de la mobilització de diferents tipus de saber que s'ajustin a la selecció d'un esquema per resoldre'ls. La proposta presentada del desplegament curricular de les competències és una eina que aporta tres avantatges. Primerament, permet seqüenciar i garantir el treball de totes les competències des de totes les àrees. En segon lloc, permet incorporar continguts metodològics competencials dins de les àrees disciplinàries. En tercer lloc, facilita que es donin les condicions necessàries per ensenyar i aprendre les competències a través de la creació de l'àmbit comú.

Experimental investigation of the initial regime in fingering electrodeposition: Dispersion relation and velocity measurements.

Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper. We present here measurements of the dispersion relation of the growing front. The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.

Decision making techniques with similarity measures and OWA operators

We analyse the use of the ordered weighted average (OWA) in decision-making giving special attention to business and economic decision-making problems. We present several aggregation techniques that are very useful for decision-making such as the Hamming distance, the adequacy coefficient and the index of maximum and minimum level. We suggest a new approach by using immediate weights, that is, by using the weighted average and the OWA operator in the same formulation. We further generalize them by using generalized and quasi-arithmetic means. We also analyse the applicability of the OWA operator in business and economics and we see that we can use it instead of the weighted average. We end the paper with an application in a business multi-person decision-making problem regarding production management

Intervenció educativa per a la millora de la detecció precoç de la depressió major en adolescents

La depressió major és una patologia mental que afecta a persones de qualsevol edat, condició econòmica, nivell educatiu, cultural i suposen un gran cost per l’individu, la família, el sistema sanitari i la comunitat en general. Es creu que una de cada cinc persones arribarà a desenvolupar un trastorn depressiu al llarg de la seva vida i que al 2020 serà la segona causa de discapacitat i de pèrdua d’anys de vida saludables a escala mundial i la primera en països desenvolupats. L’objectiu d’aquest estudi quasi experimental és millorar la detecció precoç de la simptomatologia depressiva en adolescents, descriure els factors de risc i atendre les necessitats d’aquests joves. Utilitzarem el Test de Beck Depression Inventory-2nd (BDI-II) i el Patient Health Questionnaire-Adolescent version (PHQ-9) per detectar l’estat de salut mental dels alumnes. No tenim la certesa de que la mostra sigui representativa, ja que escollim un grup intacte d’alumnes de 1r d’ ESO, del municipi de Cardedeu, amb una edat per norma general de 12 -13 anys i per tant, potser una amenaça per la nostra validació ja que el factor entorn influeix directament en la situació sociodemografica de la població escollida, la situació econòmica i familiar.