http://www.recercat.cat:80/handle/2072/4427 www.cerca.cat Tue, 21 May 2013 03:11:24 GMT 2013-05-21T03:11:24Z http://www.recercat.cat:80/bitstream/id/54338/ http://www.recercat.cat:80/handle/2072/4427 http://www.recercat.cat:80/handle/2072/205476 Statistical similarity between the compression of a porous material and earthquakes Baró, Jordi; Corral, Álvaro; Illa Vila, Xavier; Planes Vila, Antoni; Salje, Ekhard K. H.; Schranz, Wilfried; Soto-Parra, Daniel; Vives i Santa-Eulàlia, Eduard It has been long stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallelisms between these so separate phenomena. We study the Acoustic Emission events produced during the compression of Vycor (SiO&sub&2&/sub&). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate. Thu, 01 Nov 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205476 2012-11-01T00:00:00Z http://www.recercat.cat:80/handle/2072/210187 Conjugation of genetically-engineered protein phosphatases to magnetic particles for okadaic acid detection Garibo, Diana; Devic, Eric; Marty, Jean-Louis; Diogène Fadini, Jorge; Unzueta, Idoia; Blázquez, María; Campàs i Homs, Mònica This work presents the functional characterisation of a protein phosphatase 2A (PP2A) catalytic subunit obtained by genetic engineering and its conjugation to magnetic particles (MPs) via metal coordination chemistry for the subsequent development of assays for diarrheic lipophilic marine toxins. Colorimetric assays with free enzyme have allowed the determination of the best enzyme activity stabiliser, which is glycerol at 10%. They have also demonstrated that the recombinant enzyme can be as sensitive towards okadaic acid (OA) (LOD=2.3μg/L) and dinophysistoxin-1 (DTX-1) (LOD=15.2μg/L) as a commercial PP2A and, moreover, it has a higher operational stability, which makes possible to perform the protein phosphatase inhibition assay (PPIA) with a lower enzyme amount. Once conjugated to MPs, the PP2A catalytic subunit still retains its enzyme activity and it can also be inhibited by OA (LOD=30.1μg/L). Thu, 01 Dec 2011 00:00:00 GMT http://www.recercat.cat:80/handle/2072/210187 2011-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/209568 Gaviota de Audouin. Treinta años de nidificación en el Delta del Ebro Bertolero, Albert; Oro, Daniel; Genovart, Meritxell; Curcó, Antoni La punta de la banya, situada en el extremo meridional del delta del Ebro, acoge a una gran colonia nidificante de gaviota de Adouin, a la que recientemente se ha sumado un segundo núcleo reproductor asentado en el espigón portuario de la vecina localidad de SAnt Carles de la Ràpita. Al margen de las oscilaciones naturales de la colonia, la presencia de la especie en el delta del Ebro se remonta al año 1981, con un máximo histórico de 15.329 parejas censadas durante la temporada de cria del año 2006. Sun, 01 Jan 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/209568 2012-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/209324 Efficacy of elevated levels of a Citrobacter braakii phytase in turkey poult diets Esteve Garcia, Enric; Broz, Jiri; Fru, Fidelis; Ward, N. E. The efficacy of elevated levels of RONOZYME® HiPhos was assessed for turkey poults fed a low-P corn/SBM-based diet with an estimated 0.25% phytate Fri, 01 Mar 2013 00:00:00 GMT http://www.recercat.cat:80/handle/2072/209324 2013-03-01T00:00:00Z http://www.recercat.cat:80/handle/2072/208479 An integrated approach for the assessment of HAB dynamics in two NW Mediterranean bays from a GEOHAB perspective Bush, Julia A.; Cembella, Allan D., 1952-; Fernández-Tejedor, Margarita; Diogène Fadini, Jorge; Zielinski, Oliver Alfacs and Fangar Bay in the Ebro Delta, NW Mediterranean are the major sites in Catalonia for shellfish cultivation. These bays are subject to occasional closures in shellfish harvesting due to the presence of phycotoxins. Fish kills have also been associated with harmful algal blooms. The comparison of phytoplankton dynamics in both bays offers the opportunity to reveal differences in bloom patterns of species known to be harmful for the ecosystem and aquaculture activities. Field research is underway under the GEOHAB framework within the Core Research Project on HABs in Fjords and Coastal Embayments. The overall objective of this study is to improve our understanding of HAB biogeographical patterns, and key elements driving bloom dynamics in time and space within these semi-constrained embayments. Via the comparative approach we aim to improve the prediction for monitoring purposes, with a focus on Karlodinium spp. associated with massive kills of aquaculture species. This objective is addressed by incorporating long-term time series of phytoplankton identification and enumeration with the first results of recent field work in both bays. The latter includes the application of optical sensors, to yield a complementary view with enhanced spatial and temporal resolution of bloom phenomena. Fri, 01 Jan 2010 00:00:00 GMT http://www.recercat.cat:80/handle/2072/208479 2010-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/208425 Levels of PSP toxins in bivalves exposed to natural blooms of Alexandrium minutum in Catalan harbours Giménez Papiol, Gemma; Caillaud, A.; Cañete, E.; De la Iglesia González, Pablo; Eixarch Puigcerver, Helena; Fernández-Tejedor, Margarita; Franco, J.; Riobó, P.; Diogène Fadini, Jorge The development, validation, comparison and evaluation of analytical methods for marine toxins rely on the availability of toxic material. Within the project JACUMAR PSP, our interest is mainly focused on autochthonous bivalve species with the toxic profile of Alexandrium minutum, since this is the principal species involved regionally in PSP outbreaks. Mussels and oysters were exposed during few days in the harbor of Vilanova i la Geltrú, to blooms reaching a maximum A. minutum concentration of 200,000 cells L-1 in 2008, and 40,000 and 800,000 cells L-1, in 2009. Mussels, oysters and clams were exposed to one bloom of 22,000 cells L-1 in the harbor of Cambrils in 2009. In all situations higher toxic levels analyzed by HPLC-FD with postcolumn oxidation were observed in mussels (i.e. 1,200-2,500 μg eq. STX kg-1) than in oysters (i.e. 60-800 μg eq. STX kg-1) exposed to the same bloom. Blooms with higher concentrations of A. minutum did not correspond to higher levels of PSP toxins in bivalves. These differences may be explained by differences in A. minutum population dynamics, toxin production or in the physiological state or behaviour of shellfish. These results confirm that mussels concentrate more PSP toxins from A. minutum than oysters and clams. Fri, 01 Jan 2010 00:00:00 GMT http://www.recercat.cat:80/handle/2072/208425 2010-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/208419 Distribució actual de la tortuga Mediterrànea a Menorca Bertolero, Albert; Petrus, Joan A Menorca la tortuga mediterrànea Testudo hermanni és una espècie comuna que es distribueix per quasi tota l'illa. Els estudis anteriors sobre la seva distribució van ser realitzats entre els anys 1970 i 1994. Entre 2003 i 2006 es va prospectar la major part de Menorca amb la finalitat de determinar-ne la distribució actual. A partir de 3647 observacions d'exemplars, se'n va seleccionar aleatòriament una per quadrícula UTM de 0,5 x 0,5 km prospectada. Mitjançant una anàlisi kernel es va calcular que la seva distribució ocupava una superfície de 469 km2 (incloent-hi hàbitats no emprats per les tortugues, com ara zones urbanes o algunes zones boscoses). Aquesta distribució no és continua al llarg de l'illa, sinó que es formada per una sèrie de poblacions més o menys fragmentades i aïllades. D'altra banda, la distribució obtinguda coincideix amb la senyalada en treballs anteriors, la qual cosa s'interpreta com que no hi ha hagut canvis importants en la seva ocupació en els últims deu anys. Sun, 01 Jan 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/208419 2012-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/207587 Seasonal changes of whole root system conductance by a drought-tolerant grape root system Alsina Martí, Maria del Mar; Smart, David R.; Bauerle, Taryn; Herralde Traveria, Felicidad de; Biel Loscos, Carme; Stockert, Christine; Negron, Claudia; Savé i Montserrat, Robert, 1954- The role of root systems in drought tolerance is a subject of very limited information compared with above-ground responses. Adjustments to the ability of roots to supply water relative to shoot transpiration demand is proposed as a major means for woody perennial plants to tolerate drought, and is often expressed as changes in the ratios of leaf to root area (AL:AR). Seasonal root proliferation in a directed manner could increase the water supply function of roots independent of total root area (AR) and represents a mechanism whereby water supply to demand could be increased. To address this issue, seasonal root proliferation, stomatal conductance (gs) and whole root system hydraulic conductance (kr) were investigated for a drought-tolerant grape root system (Vitis berlandieri×V. rupestris cv. 1103P) and a non-drought-tolerant root system (Vitis riparia×V. rupestris cv. 101-14Mgt), upon which had been grafted the same drought-sensitive clone of Vitis vinifera cv. Merlot. Leaf water potentials (ψL) for Merlot grafted onto the 1103P root system (–0.91±0.02 MPa) were +0.15 MPa higher than Merlot on 101-14Mgt (–1.06±0.03 MPa) during spring, but dropped by approximately –0.4 MPa from spring to autumn, and were significantly lower by –0.15 MPa (–1.43±0.02 MPa) than for Merlot on 101-14Mgt (at –1.28±0.02 MPa). Surprisingly, gs of Merlot on the drought-tolerant root system (1103P) was less down-regulated and canopies maintained evaporative fluxes ranging from 35–20 mmol vine−1 s−1 during the diurnal peak from spring to autumn, respectively, three times greater than those measured for Merlot on the drought-sensitive rootstock 101-14Mgt. The drought-tolerant root system grew more roots at depth during the warm summer dry period, and the whole root system conductance (kr) increased from 0.004 to 0.009 kg MPa−1 s−1 during that same time period. The changes in kr could not be explained by xylem anatomy or conductivity changes of individual root segments. Thus, the manner in which drought tolerance was conveyed to the drought-sensitive clone appeared to arise from deep root proliferation during the hottest and driest part of the season, rather than through changes in xylem structure, xylem density or stomatal regulation. This information can be useful to growers on a site-specific basis in selecting rootstocks for grape clonal material (scions) grafted to them. Fri, 01 Jan 2010 00:00:00 GMT http://www.recercat.cat:80/handle/2072/207587 2010-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/207586 IX Jornada Tècnica de l'Arròs Jornada Tècnica de l'Arròs (9ena : 2013 : Deltebre) Només amb una millora continuada del cultiu es podran assolir els nous reptes que es presenten. La temàtica abordada serà molt variada: agronòmica, sanitat vegetal, ajuts i normatives. A més, enguany tindrem l’oportunitat d’aprofundir en el coneixement del cultiu de l’arròs a Andalusia. Per tot això, aquesta jornada tècnica ofereix a tots els arrossers la possibilitat d’ampliar els coneixements, debatre problemàtiques i alhora intercanviar experiències. Tue, 01 Jan 2013 00:00:00 GMT http://www.recercat.cat:80/handle/2072/207586 2013-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/207214 Protein phosphatase inhibition assays for okadaic acid detection in shellfish: matrix effects, applicability and comparison with LC-MS/MS analysis Garibo, Diana; Dàmaso, Esther; Eixarch Puigcerver, Helena; De la Iglesia González, Pablo de la; Fernández-Tejedor, Margarita; Diogène Fadini, Jorge; Pazos, Yolanda; Campàs i Homs, Mònica The applicability of the protein phosphatase inhibition assay (PPIA) to the determination of okadaic acid (OA) and its acyl derivatives in shellfish samples has been investigated, using a recombinant PP2A and a commercial one. Mediterranean mussel, wedge clam, Pacific oyster and flat oyster have been chosen as model species. Shellfish matrix loading limits for the PPIA have been established, according to the shellfish species and the enzyme source. A synergistic inhibitory effect has been observed in the presence of OA and shellfish matrix, which has been overcome by the application of a correction factor (0.48). Finally, Mediterranean mussel samples obtained from Rı´a de Arousa during a DSP closure associated to Dinophysis acuminata, determined as positive by the mouse bioassay, have been analysed with the PPIAs. The OA equivalent contents provided by the PPIAs correlate satisfactorily with those obtained by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Sun, 01 Jan 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/207214 2012-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206745 Technologies de procédé et de contrôle pour réduire la teneur en sel du jambon sec et des saucissons Arnau, J. (Arnau i Arboix, Jacint); Fulladosa i Tomàs, Elena; Garcia Gil, Núria; Serra Dalmau, Xavier; Guàrdia i Gasull, Ma Dolors; Gou i Botó, Pere; Comaposada i Beringues, Josep; Picouet, Pierre; Muñoz Moreno, Israel Dans certains pays européens, les produits carnés élaborés peuvent représenter près de 20% de la consommation journalière de sodium. De ce fait, les industries de la viande tentent de réduire la teneur en sel dans les produits carnés pour répondre, d’une part aux attentes des consommateurs et d’autre part aux demandes des autorités sanitaires. Le système Quick‐Dry‐Slice process (QDS®), couplé avec l’utilisation de sels substituant le chlorure de sodium (NaCl), a permis de fabriquer, avec succès, des saucisses fermentées à basse teneur en sel en réduisant le cycle de fabrication et sans ajout de NaCl supplémentaire. Les technologies de mesure en ligne non destructives, comme les rayons X et l’induction électromagnétique, permettent de classifier les jambons frais suivant leur teneur en gras, un paramètre crucial pour adapter la durée de l’étape de salaison. La technologie des rayons X peut aussi être utilisée pour estimer la quantité de sel incorporée pendant la salaison. L’information relative aux teneurs en sel et en gras est importante pour optimiser le processus d’élaboration du jambon sec en réduisant la variabilité de la teneur en sel entre les lots et dans un même lot, mais aussi pour réduire la teneur en sel du produit final. D’autres technologies comme la spectroscopie en proche infrarouge (NIRS) ou spectroscopie microondes sont aussi utiles pour contrôler le processus d’élaboration et pour caractériser et classifier les produits carnés élaborés, selon leur teneur en sel. La plupart de ces technologies peuvent être facilement appliquées en ligne dans l’industrie afin de contrôler le processus de fabrication et d’obtenir ainsi des produits carnés présentant les caractéristiques recherchées.; In some European countries, processed meat products can contribute up to 20% of the sodium intake of the diet. Therefore, meat industries are interested in reducing the salt content of meat products to match both consumer and health authority demands. The Quick‐Dry‐Slice process (QDS®) technology, in combination with the use of potassium salts as NaCl substitutes, has been successfully used to manufacture salt‐reduced fermented sausages in a short period of time and without added NaCl. Online non‐destructive technologies such as X‐ray and Electromagnetic Induction allow green hams to be classified according to their fat content which is a crucial parameter to adjust the duration of the salting period. X‐ray technologies can also be used to estimate the salt uptake after salting. Information regarding fat and salt contents is important to optimize the dry‐cured ham process by decreasing salt content variability (inter‐ and intra‐ batch) and by reducing the salt content of the final product. Other technologies such as Near Infrared Spectroscopy (NIRS) and Microwave Spectroscopy are useful to control the process and to characterize and classify the product according to its salt content. Most of these technologies can be easily implemented on line in the industry in order to control manufacturing processes, and to produce meat products with the desired characteristics. Tue, 01 Jan 2013 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206745 2013-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206454 The implementation of liquid chromatography tandem mass spectrometry for the official control of lipophilic toxins in seafood: Single-laboratory validation under four chromatographic conditions García-Altares, María; Diogène Fadini, Jorge; De la Iglesia González, Pablo de la We performed a comprehensive study to assess the fit for purpose of four chromatographic conditions for the determination of six groups of marine lipophilic toxins (okadaic acid and dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins, gymnodimine and spirolides) by LC-MS/MS to select the most suitable conditions as stated by the European Union Reference Laboratory for Marine Biotoxins (EURLMB). For every case, the elution gradient has been optimized to achieve a total run-time cycle of 12 min. We performed a single-laboratory validation for the analysis of three relevant matrices for the seafood aquaculture industry (mussels, pacific oysters and clams), and for sea urchins for which no data about lipophilic toxins have been reported before. Moreover, we have compared the method performance under alkaline conditions using two quantification strategies: the external standard calibration (EXS) and the matrix-matched standard calibration (MMS). Alkaline conditions were the only scenario that allowed detection windows with polarity switching in a 3200 QTrap mass spectrometer, thus the analysis of all toxins can be accomplished in a single run, increasing sample throughput. The limits of quantification under alkaline conditions met the validation requirements established by the EURLMB for all toxins and matrices, while the remaining conditions failed in some cases. The accuracy of the method and the matrix effects where generally dependent on the mobile phases and the seafood species. The MMS had a moderate positive impact on method accuracy for crude extracts, but it showed poor trueness for seafood species other than mussels when analyzing hydrolyzed extracts. Alkaline conditions with EXS and recovery correction for OA were selected as the most proper conditions in the context of our laboratory. This comparative study can help other laboratories to choose the best conditions for the implementation of LC-MS/MS according to their own necessities. Sun, 01 Jan 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206454 2012-01-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206198 Stochastic optimal bid to electricity markets with environmental risk constraints Cifuentes Rubiano, Julián There are many factors that influence the day-ahead market bidding strategies of a generation company (GenCo) in the current energy market framework. Environmental policy issues have become more and more important for fossil-fuelled power plants and they have to be considered in their management, giving rise to emission limitations. This work allows to investigate the influence of both the allowances and emission reduction plan, and the incorporation of the derivatives medium-term commitments in the optimal generation bidding strategy to the day-ahead electricity market. Two different technologies have been considered: the coal thermal units, high-emission technology, and the combined cycle gas turbine units, low-emission technology. The Iberian Electricity Market and the Spanish National Emissions and Allocation Plans are the framework to deal with the environmental issues in the day-ahead market bidding strategies. To address emission limitations, some of the standard risk management methodologies developed for financial markets, such as Value-at-Risk (VaR) and Conditional Value-at-Risk (CVaR), have been extended. This study offers to electricity generation utilities a mathematical model to determinate the individual optimal generation bid to the wholesale electricity market, for each one of their generation units that maximizes the long-run profits of the utility abiding by the Iberian Electricity Market rules, the environmental restrictions set by the EU Emission Trading Scheme, as well as the restrictions set by the Spanish National Emissions Reduction Plan. The economic implications for a GenCo of including the environmental restrictions of these National Plans are analyzed and the most remarkable results will be presented. Thu, 01 Nov 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206198 2012-11-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206096 Equidistribution estimates for Fekete points on complex manifolds Lev, Nir; Ortega Cerdà, Joaquim We study the equidistribution of Fekete points in a compact complex manifold. These are extremal point configurations defined through sections of powers of a positive line bundle. Their equidistribution is a known result. The novelty of our approach is that we relate them to the problem of sampling and interpolation on line bundles, which allows us to estimate the equidistribution of the Fekete points quantitatively. In particular we estimate the Kantorovich-Wasserstein distance of the Fekete points to its limiting measure. The sampling and interpolation arrays on line bundles are a subject of independent interest, and we provide necessary density conditions through the classical approach of Landau, that in this context measures the local dimension of the space of sections of the line bundle. We obtain a complete geometric characterization of sampling and interpolation arrays in the case of compact manifolds of dimension one, and we prove that there are no arrays of both sampling and interpolation in the more general setting of semipositive line bundles. Thu, 01 Nov 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206096 2012-11-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206095 Kuranishi type Moduli Spaces for proper CR submersions fibering over the circle Meersseman, Laurent Kuranishi's fundamental result (1962) associates to any compact complex manifold X&sub&0&/sub& a finite-dimensional analytic space which has to be thought of as a local moduli space of complex structures close to X&sub&0&/sub&. In this paper, we give an analogous statement for Levi-flat CR manifolds fibering properly over the circle by describing explicitely an infinite-dimensional Kuranishi type local moduli space of Levi-flat CR structures. We interpret this result in terms of Kodaira-Spencer deformation theory making clear the likenesses as well as the differences with the classical case. The article ends with applications and examples. Mon, 01 Oct 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206095 2012-10-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206094 Normal forms, stability and splitting of invariant manifolds II. Finitely differentiable Hamiltonians Bounemoura, Abed This paper is a sequel to ``Normal forms, stability and splitting of invariant manifolds I. Gevrey Hamiltonians", in which we gave a new construction of resonant normal forms with an exponentially small remainder for near-integrable Gevrey Hamiltonians at a quasi-periodic frequency, using a method of periodic approximations. In this second part we focus on finitely differentiable Hamiltonians, and we derive normal forms with a polynomially small remainder. As applications, we obtain a polynomially large upper bound on the stability time for the evolution of the action variables and a polynomially small upper bound on the splitting of invariant manifolds for hyperbolic tori. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206094 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206093 Normal forms, stability and splitting of invariant manifolds I. Gevrey Hamiltonians Bounemoura, Abed In this paper, we give a new construction of resonant normal forms with a small remainder for near-integrable Hamiltonians at a quasi-periodic frequency. The construction is based on the special case of a periodic frequency, a Diophantine result concerning the approximation of a vector by independent periodic vectors and a technique of composition of periodic averaging. It enables us to deal with non-analytic Hamiltonians, and in this first part we will focus on Gevrey Hamiltonians and derive normal forms with an exponentially small remainder. This extends a result which was known for analytic Hamiltonians, and only in the periodic case for Gevrey Hamiltonians. As applications, we obtain an exponentially large upper bound on the stability time for the evolution of the action variables and an exponentially small upper bound on the splitting of invariant manifolds for hyperbolic tori, generalizing corresponding results for analytic Hamiltonians. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206093 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206092 Holomorphic maps between moduli spaces Aramayona, Javier; Souto, Juan A. We prove that every non-constant holomorphic map&em&M&/em&&sub&g,p&/sub&→ &em&M&/em&&sub& g',p'&/sub& between moduli spaces of Riemann surfaces is a forgetful map, provided that g ≥ 6 and g' ≤ 2g-2. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206092 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206091 Rigidity phenomena in the mapping class group Aramayona, Javier; Souto, Juan A Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206091 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/206090 Variétés CR polarisées et G-polarisées, partie I Meersseman, Laurent Polarized and G-polarized CR manifolds are smooth manifolds endowed with a double structure: a real foliation &em&F&/em& (given by the action of a Lie group G in the G-polarized case) and a transverse CR distribution. Polarized means that (E,J) is roughly speaking invariant by&em&F&/em&. Both structures are therefore linked up. The interplay between them gives to polarized CR-manifolds a very rich geometry. In this paper, we study the properties of polarized and G-polarized manifolds, putting special emphasis on their deformations. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/206090 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/205953 Modelling the cardiovascular system for automatic interpretation of the blood pressure curve Myers, Timothy; Sáez de Tejada, Anna; McGuinness, Mark J.; Mitchell, Sarah L.; Ribas Ripoll, Vicent Jordi A four compartment model of the cardiovascular system is developed. To allow for easy interpretation and to minimise the number of parameters, an effort was made to keep the model as simple as possible. A sensitivity analysis is first carried out to determine which are the most important model parameters to characterise the blood pressure signal. A four stage process is then described which accurately determines all parameter values. This process is applied to data from three patients and good agreement is shown in all cases. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205953 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/205485 On concentrators and related approximation constants Bondarenko, Andriy; Prymak, A; Radchenko, Danylo Pippenger [Pi77] showed the existence of (6m,4m,3m,6)-concentrator for each positive integer m using a probabilistic method. We generalize his approach and prove existence of (6m,4m,3m,5.05)-concentrator (which is no longer regular, but has fewer edges). We apply this result to improve the constant of approximation of almost additive set functions by additive set functions from 44.5 (established by Kalton and Roberts in [KaRo83] to 39. We show a more direct connection of the latter problem to the Whitney type estimate for approximation of continuous functions on a cube in &b&R&/b&&sup&d&/sup& by linear functions, and improve the estimate of this Whitney constant from 802 (proved by Brudnyi and Kalton in [BrKa00] to 73. Sat, 01 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205485 2012-12-01T00:00:00Z http://www.recercat.cat:80/handle/2072/205484 One-dimensional solidification of supercooled melts Font Martínez, Francesc; Myers, T. G.; Mittchell, Sara L. In this paper a one-phase supercooled Stefan problem, with a nonlinear relation between the phase change temperature and front velocity, is analysed. The model with the standard linear approximation, valid for small supercooling, is first examined asymptotically. The nonlinear case is more difficult to analyse and only two simple asymptotic results are found. Then, we apply an accurate heat balance integral method to make further progress. Finally, we compare the results found against numerical solutions. The results show that for large supercooling the linear model may be highly inaccurate and even qualitatively incorrect. Similarly as the Stefan number β → 1&sup&+&/sup& the classic Neumann solution which exists down to β =1 is far from the linear and nonlinear supercooled solutions and can significantly overpredict the solidification rate. Tue, 04 Dec 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205484 2012-12-04T00:00:00Z http://www.recercat.cat:80/handle/2072/205482 Feuilletages par variétés complexes et problèmes d'uniformisation Meersseman, Laurent Ce texte est une introduction aux feuilletages par variétés complexes et aux problèmes d'uniformisation de tels feuilletages. Nous donnons en introduction une liste fondamentale de questions naturelles sur ces objets ainsi qu'un aperçcu des résultats connus. Thu, 01 Nov 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205482 2012-11-01T00:00:00Z http://www.recercat.cat:80/handle/2072/205479 Tenseness of Riemannian flows Nozawa, Hiraku; Royo Prieto, José Ignacio We show that any transversally complete Riemannian foliation &em&F&/em& of dimension one on any possibly non-compact manifold M is tense; namely, (M,&em&F&/em&) admits a Riemannian metric such that the mean curvature form of &em&F&/em& is basic. This is a partial generalization of a result of Domínguez, which says that any Riemannian foliation on any compact manifold is tense. Our proof is based on some results of Molino and Sergiescu, and it is simpler than the original proof by Domínguez. As an application, we generalize some well known results including Masa's characterization of tautness. Thu, 01 Nov 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/205479 2012-11-01T00:00:00Z http://www.recercat.cat:80/handle/2072/204756 Folner sequences and finite operators Yakubovich, Dmitry V.; Lledó, Fernando,1967- This article analyzes Folner sequences of projections for bounded linear operators and their relationship to the class of finite operators introduced by Williams in the 70ies. We prove that each essentially hyponormal operator has a proper Folner sequence (i.e. a Folner sequence of projections strongly converging to 1). In particular, any quasinormal, any subnormal, any hyponormal and any essentially normal operator has a proper Folner sequence. Moreover, we show that an operator is finite if and only if it has a proper Folner sequence or if it has a non-trivial finite dimensional reducing subspace. We also analyze the structure of operators which have no Folner sequence and give examples of them. For this analysis we introduce the notion of strongly non-Folner operators, which are far from finite block reducible operators, in some uniform sense, and show that this class coincides with the class of non-finite operators. Mon, 01 Oct 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/204756 2012-10-01T00:00:00Z http://www.recercat.cat:80/handle/2072/204699 Stability of cascade networks via fluid models Delgado de la Torre, Rosario; Morozov, Evsey Vegeu el resum a l'inici del document de l'arxiu adjunt Mon, 01 Oct 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/204699 2012-10-01T00:00:00Z http://www.recercat.cat:80/handle/2072/204697 An energy preserving discontinouous Galerkin method for Vlasov-Poisson system Hajian, Soheil Vegeu el resum a l'inici del document de l'arxiu adjunt Thu, 01 Sep 2011 00:00:00 GMT http://www.recercat.cat:80/handle/2072/204697 2011-09-01T00:00:00Z http://www.recercat.cat:80/handle/2072/204696 Young Set Theory Workshop : Centre de Recerca Matemàtica, 14-18 April 2009 Young Set Theory Workshop (2009 : Bellaterra, Catalunya) Wed, 01 Feb 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/204696 2012-02-01T00:00:00Z http://www.recercat.cat:80/handle/2072/204381 Semi-analytical implementation for the name concentration measurement in a credit portfolio Álvarez Jordan, Sandra Fri, 01 Jun 2012 00:00:00 GMT http://www.recercat.cat:80/handle/2072/204381 2012-06-01T00:00:00Z