Estudi ambiental del Centre Esportiu Puigverd: aigua, residus i característiques físiques

El medi ambient està creixent i adquirint actualment una importància fins ara mai vista. La societat reconeix el medi ambient com un factor de benestar social i personal, i alhora una característica de modernitat. En aquest estudi s’analitzen tots els factors ambientals presents en l’activitat quotidiana d’un centre esportiu. El centre escollit es troba situat en el municipi de Castellar del Vallès, a la comarca del Vallès Occidental, província de Barcelona. Aquest centre construït fa 17 anys per la demanda continua dels habitants del poble i per les pressions dels nuclis urbans pròxims, ha sofert uns canvis que actualment encara estan presents. Els objectius de l’estudi són la descripció, l’anàlisi i el tractament de la gestió actual del centre envers els recursos utilitzats. L’aigua, els residus i per últim les propietats físiques de l’edificació, com a innovació en aquesta tipologia d’estudis. L’anàlisi i tractament d’aquests, permet conèixer els punts forts i febles del centre. Les flaqueses observades afecten majoritàriament als factors ambientals. Conseqüentment, es dissenyen unes propostes de millora per tal de poder minimitzar els impactes soferts i redireccionar la gestió ambiental del centre, afrontant així un futur amb un desenvolupament sostenible.

Stochastic semiclassical equations for weakly inhomogeneous cosmologies

Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar field in a spatially flat cosmological background are derived. Use is made of the fact that for this problem the in-in or closed time path effective action is simply related to the Feynman-Vernon influence functional which describes the effect of the ``environment,'' the quantum field which is coarse grained here, on the ``system,'' the gravitational field which is the field of interest. This leads to identify the dissipation and noise kernels in the in-in effective action, and to derive a fluctuation-dissipation relation. A tensorial Gaussian stochastic source which couples to the Weyl tensor of the spacetime metric is seen to modify the usual semiclassical equations which can be veiwed now as mean field equsations. As a simple application we derive the correlation functions of the stochastic metric fluctuations produced in a flat spacetime with small metric perturbations due to the quantum fluctuations of the matter field coupled to these perturbations.

Seguidilles, fandangos i boleros a les sonates ibèriques per tecla dels compositors Domenico Scarlatti, José de Nebra i Antoni Soler

Aquest projecte neix amb la finalitat d’oferir una perspectiva sobre les sonates ibèriques de les dècades centrals del segle XVIII, i en concret dels cèlebres compositors Domenico Scarlatti, José de Nebra i Antoni Soler, centrada en alguns dels balls de major popularitat a l’època com són les seguidilles, els fandangos i els boleros. Algunes de les sonates ibèriques d’aquests compositors es corresponen amb molts dels paràmetres que condicionen aquests balls i com a conseqüència són sonates que poden ser ballades, tot i que desconeixem si a l’època s’interpretaven amb ballarins. Al voltant d’aquest tema se’ns formulen algunes preguntes referents al gènere i l’estil de les sonates o a la relació dels seus compositors amb els moviments culturals de la ciutat de Madrid que podien haver propiciat aquesta connexió.

On the closed-form approximation of short-time random strike options

In this paper we propose a general technique to develop first and second order closed-form approximation formulas for short-time options withrandom strikes. Our method is based on Malliavin calculus techniques andallows us to obtain simple closed-form approximation formulas dependingon the derivative operator. The numerical analysis shows that these formulas are extremely accurate and improve some previous approaches ontwo-assets and three-assets spread options as Kirk's formula or the decomposition mehod presented in Alòs, Eydeland and Laurence (2011).

Parrondo-like behavior in continuous-time random walks with memory

The continuous-time random walk (CTRW) formalism can be adapted to encompass stochastic processes with memory. In this paper we will show how the random combination of two different unbiased CTRWs can give rise to a process with clear drift, if one of them is a CTRW with memory. If one identifies the other one as noise, the effect can be thought of as a kind of stochastic resonance. The ultimate origin of this phenomenon is the same as that of the Parrondo paradox in game theory.

Statistical treatment of grain-size curves and empirical distributions: densities as compositions?

The preceding two editions of CoDaWork included talks on the possible considerationof densities as infinite compositions: Egozcue and D´ıaz-Barrero (2003) extended theEuclidean structure of the simplex to a Hilbert space structure of the set of densitieswithin a bounded interval, and van den Boogaart (2005) generalized this to the setof densities bounded by an arbitrary reference density. From the many variations ofthe Hilbert structures available, we work with three cases. For bounded variables, abasis derived from Legendre polynomials is used. For variables with a lower bound, westandardize them with respect to an exponential distribution and express their densitiesas coordinates in a basis derived from Laguerre polynomials. Finally, for unboundedvariables, a normal distribution is used as reference, and coordinates are obtained withrespect to a Hermite-polynomials-based basis.To get the coordinates, several approaches can be considered. A numerical accuracyproblem occurs if one estimates the coordinates directly by using discretized scalarproducts. Thus we propose to use a weighted linear regression approach, where all k-order polynomials are used as predictand variables and weights are proportional to thereference density. Finally, for the case of 2-order Hermite polinomials (normal reference)and 1-order Laguerre polinomials (exponential), one can also derive the coordinatesfrom their relationships to the classical mean and variance.Apart of these theoretical issues, this contribution focuses on the application of thistheory to two main problems in sedimentary geology: the comparison of several grainsize distributions, and the comparison among different rocks of the empirical distribution of a property measured on a batch of individual grains from the same rock orsediment, like their composition

Compositional evolution with mass transfer in closed systems

Evolution of compositions in time, space, temperature or other covariates is frequentin practice. For instance, the radioactive decomposition of a sample changes its composition with time. Some of the involved isotopes decompose into other isotopes of thesample, thus producing a transfer of mass from some components to other ones, butpreserving the total mass present in the system. This evolution is traditionally modelledas a system of ordinary di erential equations of the mass of each component. However,this kind of evolution can be decomposed into a compositional change, expressed interms of simplicial derivatives, and a mass evolution (constant in this example). A rst result is that the simplicial system of di erential equations is non-linear, despiteof some subcompositions behaving linearly.The goal is to study the characteristics of such simplicial systems of di erential equa-tions such as linearity and stability. This is performed extracting the compositional differential equations from the mass equations. Then, simplicial derivatives are expressedin coordinates of the simplex, thus reducing the problem to the standard theory ofsystems of di erential equations, including stability. The characterisation of stabilityof these non-linear systems relays on the linearisation of the system of di erential equations at the stationary point, if any. The eigenvelues of the linearised matrix and theassociated behaviour of the orbits are the main tools. For a three component system,these orbits can be plotted both in coordinates of the simplex or in a ternary diagram.A characterisation of processes with transfer of mass in closed systems in terms of stability is thus concluded. Two examples are presented for illustration, one of them is aradioactive decay

Impedance boundary conditions for pseudo-spectral time-domain methods in room acoustics

The pseudo-spectral time-domain (PSTD) method is an alternative time-marching method to classicalleapfrog finite difference schemes in the simulation of wave-like propagating phenomena. It is basedon the fundamentals of the Fourier transform to compute the spatial derivatives of hyperbolic differential equations. Therefore, it results in an isotropic operator that can be implemented in an efficient way for room acoustics simulations. However, one of the first issues to be solved consists on modeling wallabsorption. Unfortunately, there are no references in the technical literature concerning to that problem. In this paper, assuming real and constant locally reacting impedances, several proposals to overcome this problem are presented, validated and compared to analytical solutions in different scenarios.

Impedance boundary conditions for pseudo-spectral time-domain methods in room acoustics

The Pseudo-Spectral Time Domain (PSTD) method is an alternative time-marching method to classical leapfrog finite difference schemes inthe simulation of wave-like propagating phenomena. It is based on the fundamentals of the Fourier transform to compute the spatial derivativesof hyperbolic differential equations. Therefore, it results in an isotropic operator that can be implemented in an efficient way for room acousticssimulations. However, one of the first issues to be solved consists on modeling wall absorption. Unfortunately, there are no references in thetechnical literature concerning to that problem. In this paper, assuming real and constant locally reacting impedances, several proposals toovercome this problem are presented, validated and compared to analytical solutions in different scenarios.

Sequential estimation of time-varying multipath channel for MIMO-OFDM systems

In this paper, we introduce a pilot-aided multipath channel estimator for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. Typical estimation algorithms assume the number of multipath components and delays to be known and constant, while theiramplitudes may vary in time. In this work, we focus on the more realistic assumption that also the number of channel taps is unknown and time-varying. The estimation problem arising from this assumption is solved using Random Set Theory (RST), which is a probability theory of finite sets. Due to the lack of a closed form of the optimal filter, a Rao-Blackwellized Particle Filter (RBPF) implementation of the channel estimator is derived. Simulation results demonstrate the estimator effectiveness.

A comparison of full-rate full-diversity 2x2 space-time codes for WiMAX systems

Multiple-input multiple-output (MIMO) techniques have become an essential part of broadband wireless communications systems. For example, the recently developed IEEE 802.16e specifications for broadband wireless access include three MIMOprofiles employing 2×2 space-time codes (STCs), and two of these MIMO schemes are mandatory on the downlink of Mobile WiMAX systems. One of these has full rate, and the other has full diversity, but neither of them has both of the desired features. The third profile, namely, Matrix C, which is not mandatory, is both a full rate and a full diversity code, but it has a high decoder complexity. Recently, the attention was turned to the decodercomplexity issue and including this in the design criteria, several full-rate STCs were proposed as alternatives to Matrix C. In this paper, we review these different alternatives and compare them to Matrix C in terms of performances and the correspondingreceiver complexities.

A consistency test of the time trade-off

This paper tests the internal consistency of time trade-off utilities.We find significant violations of consistency in the direction predictedby loss aversion. The violations disappear for higher gauge durations.We show that loss aversion can also explain that for short gaugedurations time trade-off utilities exceed standard gamble utilities. Ourresults suggest that time trade-off measurements that use relativelyshort gauge durations, like the widely used EuroQol algorithm(Dolan 1997), are affected by loss aversion and lead to utilities thatare too high.

Realització d'una aplicació de gestió de xarxes per a la xarxa sensefils de Manresa GuifiBages

En els últims anys, la popularitat de les xarxes sensefils (WIFI) ha anat en augment a un ritme incansable. Des de petits aparells instal•lats a les cases amb aquesta tecnologia com a complement dels routers d’accés a internet instal•lats per diverses companyies, fins a empreses fent petits desplegaments per comunicar entre si les seves seus. Al marge d’aquests escenaris, s’ha produït un fenomen social d’acolliment d’aquesta tecnologia a nivell mundial, en forma del que coneixem com a xarxes ciutadanes / xarxes lliures / xarxes socials. Aquestes xarxes han estat possibles gràcies a diverses raons que han fet assequible a col•lectius de persones, tant els aparells com els coneixements necessaris per dur a terme aquestes actuacions. Dintre d’aquest marc, al Bages, concretament a Manresa, es va començar a desenvolupar una d’aquestes xarxes. Les decisions d’aquesta xarxa d’utilitzar exclusivament hardware i software de codi obert, i determinats aspectes tècnics de la xarxa, ha comportat que la xarxa fos incompatible amb algunes de les aplicacions de gestió de xarxes existents desenvolupades per comunicats com gufi.net a Osona. És per això que per garantir el creixement, la supervivència i l’èxit d’aquesta xarxa en el temps, és indispensable poder comptar amb una eina de gestió que s’adigui a les característiques de GuifiBages. L’objectiu principal d’aquest treball és dotar a la xarxa GuifiBages de les eines necessàries per poder gestionar tota la informació referent a l’estructura de la seva xarxa, tant per facilitar l’accés a nous usuaris sense molts coneixements tècnics, com per facilitar nous desplegaments / reparacions / modificacions de la xarxa d’una manera automàtica. Com a conclusió d’aquest treball, podem afirmar que les avantatges que proporciones tecnologies com Plone, faciliten enormement la creació d’aplicacions de gestió de continguts en entorn web. Alhora, l’ús de noves tècniques de programació com AJAX o recursos com els que ofereix Google, permeten desenvolupar aplicacions web que no tenen res a envejar al software tradicional. D’altra banda, voldríem destacar l’ús exclusiu de programari lliure tant en els paquets de software necessaris pel desenvolupament, com en el sistema operatiu i programes dels ordinadors on s’ha dut a terme, demostrant que es poden desenvolupar sistemes de qualitat sense dependre de programari privatiu.

Time-scale and other invariants of integrative mechanical behavior in living cells.

In dealing with systems as complex as the cytoskeleton, we need organizing principles or, short of that, an empirical framework into which these systems fit. We report here unexpected invariants of cytoskeletal behavior that comprise such an empirical framework. We measured elastic and frictional moduli of a variety of cell types over a wide range of time scales and using a variety of biological interventions. In all instances elastic stresses dominated at frequencies below 300 Hz, increased only weakly with frequency, and followed a power law; no characteristic time scale was evident. Frictional stresses paralleled the elastic behavior at frequencies below 10 Hz but approached a Newtonian viscous behavior at higher frequencies. Surprisingly, all data could be collapsed onto master curves, the existence of which implies that elastic and frictional stresses share a common underlying mechanism. Taken together, these findings define an unanticipated integrative framework for studying protein interactions within the complex microenvironment of the cell body, and appear to set limits on what can be predicted about integrated mechanical behavior of the matrix based solely on cytoskeletal constituents considered in isolation. Moreover, these observations are consistent with the hypothesis that the cytoskeleton of the living cell behaves as a soft glassy material, wherein cytoskeletal proteins modulate cell mechanical properties mainly by changing an effective temperature of the cytoskeletal matrix. If so, then the effective temperature becomes an easily quantified determinant of the ability of the cytoskeleton to deform, flow, and reorganize.

Mean first-passage time of continuous non-Markovian processes driven by colored noise

An equation for mean first-passage times of non-Markovian processes driven by colored noise is derived through an appropriate backward integro-differential equation. The equation is solved in a Bourret-like approximation. In a weak-noise bistable situation, non-Markovian effects are taken into account by an effective diffusion coefficient. In this situation, our results compare satisfactorily with other approaches and experimental data.