Showing papers by "University of Seville published in 2005"
TL;DR: In this paper, a new approach for the development of planar metamaterial structures is developed, and analytical equivalent circuit models are proposed for isolated and coupled split-ring resonators/CSRRs coupled to planar transmission lines.
Abstract: In this paper, a new approach for the development of planar metamaterial structures is developed. For this purpose, split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) coupled to planar transmission lines are investigated. The electromagnetic behavior of these elements, as well as their coupling to the host transmission line, are studied, and analytical equivalent-circuit models are proposed for the isolated and coupled SRRs/CSRRs. From these models, the stopband/passband characteristics of the analyzed SRR/CSRR loaded transmission lines are derived. It is shown that, in the long wavelength limit, these stopbands/passbands can be interpreted as due to the presence of negative/positive values for the effective /spl epsiv/ and /spl mu/ of the line. The proposed analysis is of interest in the design of compact microwave devices based on the metamaterial concept.
1,405 citations
TL;DR: A powerful in vivo activity of α-synuclein is revealed in protecting nerve terminals against injury and it is suggested that this activity operates in conjunction with CSPα and SNARE proteins on the presynaptic membrane interface.
881 citations
TL;DR: Its strong anti-inflammatory activity and the plausible mechanisms of these effects are reviewed to provide the reader an up-date of the bioavailability and pharmacokinetics of resveratrol and its impact on lifespan.
Abstract: Resveratrol is a phytoalexin polyphenolic compound found in various plants, including grapes, berries, and peanuts. Multiple lines of compelling evidence indicate its beneficial effects on neurological, hepatic, and cardiovascular systems. Also one of the most striking biological activities of resveratrol soundly investigated during the late years has been its cancer-chemopreventive potential. In fact, recently it has been demonstrated that this stilbene blocks the multistep process of carcinogenesis at various stages: tumor initiation, promotion, and progression. One of the possible mechanisms for its biological activities involves downregulation of the inflammatory response through inhibition of synthesis and release of pro-inflammatory mediators, modification of eicosanoid synthesis, inhibition of activated immune cells, or inhibiting such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) via its inhibitory effects on nuclear factor (kappa)B (NF-(kappa)B) or the activator protein-1 (AP-1). More recent data provide interesting insights into the effect of this compound on the lifespan of yeast and flies, implicating the potential of resveratrol as an anti-aging agent in treating age-related human diseases. It is worthy to note that the phenolic compound possesses a low bioavailability and rapid clearance from the plasma. As the positive effects of resveratrol on inflammatory response regulation may comprise relevant clinical implications, the purpose of this article is to review its strong anti-inflammatory activity and the plausible mechanisms of these effects. Also, this review is intended to provide the reader an up-date of the bioavailability and pharmacokinetics of resveratrol and its impact on lifespan.
660 citations
TL;DR: A design example showing the application of the FVF to build systems based on translinear loops is described which shows the potential of this cell for the design of high-performance low-power/low-voltage analog and mixed-signal circuits.
Abstract: In this paper, a basic cell for low-power and/or low-voltage operation is identified. It is evidenced how different versions of this cell, coined as "flipped voltage follower (FVF)" have been used in the past for many applications. A detailed classification of basic topologies derived from the FVF is given. In addition, a comprehensive list of recently proposed low-voltage/low-power CMOS circuits based on the FVF is given. Although the paper has a tutorial taste, some new applications of the FVF are also presented and supported by a set of simulated and experimental results. Finally, a design example showing the application of the FVF to build systems based on translinear loops is described which shows the potential of this cell for the design of high-performance low-power/low-voltage analog and mixed-signal circuits.
622 citations
TL;DR: The presence of immune system-synthesized melatonin, its direct immunomodulatory effects on cytokine production, and its masking effects on exogenous melatonin action are summarized.
Abstract: This review summarizes the numerous observations published in recent years which have shown that one of the most significant of melatonin’s pleiotropic effects is the regulation of the immune system. The overview summarizes the immune effects of pinealectomy and the association between rhythmic melatonin production and adjustments in the immune system as markers of melatonin’s immunomodulatory actions. The effects of both in vivo and in vitro melatonin administration on non-specific, humoral, and cellular immune responses as well as on cellular proliferation and immune mediator production are presented. One of the main features that distinguishes melatonin from the classical hormones is its synthesis by a number of nonendocrine extrapineal organs, including the immune system. Herein, we summarize the presence of immune system-synthesized melatonin, its direct immunomodulatory effects on cytokine production, and its masking effects on exogenous melatonin action. The mechanisms of action of melatonin in the immune system are also discussed, focusing attention on the presence of membrane and nuclear receptors and the characterization of several physiological roles mediated by some receptor analogs in immune cells. The review focuses on melatonin’s actions in several immune pathologies including infection, inflammation, and autoimmunity together with the relation between melatonin, immunity, and cancer.
605 citations
17 Jun 2005
TL;DR: A proposal to model and reason on an SPL using constraint programming is introduced, taking into account functional and extra–functional features, improve current proposals and present a running, yet feasible implementation.
Abstract: Software Product Line (SPL) Engineering has proved to be an effective method for software production. However, in the SPL community it is well recognized that variability in SPLs is increasing by the thousands. Hence, an automatic support is needed to deal with variability in SPL. Most of the current proposals for automatic reasoning on SPL are not devised to cope with extra–functional features. In this paper we introduce a proposal to model and reason on an SPL using constraint programming. We take into account functional and extra–functional features, improve current proposals and present a running, yet feasible implementation.
603 citations
TL;DR: This paper presents a new approach to guaranteed state estimation for non-linear discrete-time systems with a bounded description of noise and parameters with an algorithm to compute a set that contains the states consistent with the measured output and the given Noise and parameters.
555 citations
TL;DR: In this article, a trabajo tiene por objeto la determinación del indice de fenoles totales, antocianos totales (AT) and the capacidad antioxidante of las pulpas de frutos congelados, aplicando los metodos espectrofotometrico quimicos mas en boga for la determinacion de la actividad antioxidante (ABTS, DPPH, and DMPD).
Abstract: El Brazil es considerado un de los principales paises productores de zumos de frutos, ocupando en concreto la tercera posicion respecto a esto. La diversidad de frutos en el mercado es cada vez mayor, introduciendose diariamente nuevos frutos tropicales cuyas propiedades y actividades no estan aun totalmente determinadas. El gobierno brasileno apoya el comercio exterior de frutos, invirtiendo fondos en exposiciones que promueven y situan a los nuevos productos en los paises de la Union Europea, tal como la "Brazilian Fruit Festival" que promociona frutos in natura, pulpas congeladas y zumos procesados. Se publican cada vez en mayor numero nuevas investigaciones que asocian el consumo de frutas con efectos beneficiosos para la salud humana. Este trabajo tiene por objeto la determinacion del indice de fenoles totales (FT), antocianos totales (AT) y la capacidad antioxidante de las pulpas de frutos comerciales congelados, aplicando los metodos espectrofotometrico quimicos mas en boga para la determinacion de la actividad antioxidante (ABTS, DPPH y DMPD). Se ha determinado la capacidad antioxidante de las pulpas de los frutos tropicales de mayor consumo en el mercado del sur de Brazil (mora, uva, acai, guayaba, fresa, acerola, pina, mango, graviola, cupuacu y maracuya) aplicando el metodo ABTS con medidas a dos tiempos (1 y 7 minutos), DPPH (30 y 60 minutos) y DMPD (10 minutos). Los valores TEAC (capacidad antioxidante equivalente al Trolox) obtenidos de las pulpas oscilan entre minimos y maximos de 2,0 y 67,2 µmol/g aplicando el ensayo ABTS, 1,02 y 67,0 µmol/g aplicando DPPH y 4,2 y 46,6 µmol/g aplicando DMPD. La capacidad antioxidante obtenida por los metodos ABTS y DPPH se encuentra correlacionada con el contenido de compuestos fenolicos y antocianos.
452 citations
TL;DR: The physics of granular materials in ambient gases is governed by interparticle forces, gas-particle interaction, geometry of particle positions and geometry of particles contacts as mentioned in this paper, which are strongly dependent on the external forces, boundary conditions and on the assembling procedure.
Abstract: Memento, homo, qui pulvis est et pulverem reverteris. Genesis 3 Polvos seran, mas polvo enamorado. Francisco de Quevedo The physics of granular materials in ambient gases is governed by interparticle forces, gas–particle interaction, geometry of particle positions and geometry of particle contacts. At low consolidations these are strongly dependent on the external forces, boundary conditions and on the assembling procedure. For dry fine powders of micron and sub-micron particle size interparticle attractive forces are typically much higher than particle weight, and particles tend to aggregate. Because of this, cohesive powders fracture before breaking, flow and avalanche in coherent blocks much larger than the particle size. Similarly the drag force for micron sized particles is large compared to their weight for velocities as low as 1 mm/s. Due to this extreme sensitivity to interstitial gas flow, powders transit directly from plastic dense flows to fluidization without passing through collisional re...
450 citations
TL;DR: This review discusses recent advances in the understanding of the ways in which different organs detect and respond to acute changes in oxygen tension.
Abstract: This review discusses recent advances in the understanding of the ways in which different organs detect and respond to acute changes in oxygen tension. A group of specialized tissues constitutes an oxygen-sensing system that responds rapidly to even minor changes in oxygen tension.
445 citations
TL;DR: In this paper, photoactive titania powders with variable amount of anatase and rutile phases were prepared by heating of pure anatase in the temperatutre range 800-1150°C.
Abstract: Nanosized titanium dioxide photocatalysts with varying amount of anatase and rutile phases have been synthesized. Homogeneous precipitation of aqueous solutions containing TiOSO 4 with urea was used to prepare porous spherical clusters of anatase TiO 2. Photoactive titania powders with variable amount of anatase and rutile phases were prepared by heating of pure anatase in the temperatutre range 800–1150 °C. The structure evolution during heating of the starting anatase powders was studied by XRD analysis in overall temperature range of phase transformation. The morphology and microstucture characteristics were also obtained by HRTEM, BET and BJH. The spherical particle morphology of TiO 2 mixtures determined by SEM was stable in air up to 900 °C. The photocatalytic activity of the sample titania TIT85/825 heated to 825 °C in air, contained 77.4% anatase and 22.6% rutile was higher than that nanocrystalline anatase powder. Titania sample TIT85/825 reveals the highest catalytic activity during the photocatalyzed degradation of 4-chlorophenol in aqueous suspension.
TL;DR: In this paper, a compilation of the solutions or initiatives that can be implemented by local administrations in order to improve freight deliveries in urban environments is presented, which are classified into those related to public infrastructure, land use management, access conditions, traffic management, enforcement and promotion.
TL;DR: This work identified Shewanella algae, an environmental species from marine and fresh water, as its reservoir and is one of the very few examples of progenitor identification of an acquired antibiotic resistance gene.
Abstract: Plasmid-mediated resistance to quinolones is increasingly reported in studies of Enterobacteriaceae. Using a PCR-based strategy, a series of gram-negative species were screened for qnrA-like genes. Shewanella algae, an environmental species from marine and fresh water, was identified as its reservoir. This is a one of the very few examples of progenitor identification of an acquired antibiotic resistance gene.
TL;DR: In this paper, the main sensory defects found in virgin olive oil (winey-vinegary, mustiness-humidity, fusty and rancid) were studied by dynamic headspace high-resolution gas chromatography with flame ionisation and mass spectrometry detection.
TL;DR: Clinical studies showed that ethosomal systems were much more efficient at delivering the fluorescent substance into the skin in terms of quantity and depth, than either liposomes or hydroalcoholic solutions.
TL;DR: In this article, a structural equation modeling (SEM) specifically partial least squares (PLS) is proposed to assess the relationships between the constructs together with the predictive power of the research model.
Abstract: Purpose – To analyse the web acceptance and usage between goal‐directed users and experiential users, incorporating intrinsic motives to improve the particular and explanatory TAM (technology acceptance model) value – traditionally related to extrinsic motives.Design/methodology/approach – A survey instrument was used to gather data to test the relationships shown in the research model. Data were collected from a sample of online questionnaires filled out by subscribers located in three discussion‐mailing lists – administered by RedIris – about different topics (e.g. experimental sciences, social sciences and humanities). A structural equation modeling (SEM), specifically partial least squares (PLS), is proposed to assess the relationships between the constructs together with the predictive power of the research model.Findings – The empirical development suggests that there is scope for further extension of TAM to adapt to the web‐based usage and its profitable consequences. The article may help to furthe...
TL;DR: In this paper, the impact of marketing communications and price promotion on brand equity has been analyzed empirically, using structural equations models to confirm empirically the relationship between marketing communication efforts and the dimensions of brand equity: perceived quality, brand loyalty, brand awareness and brand image.
Abstract: This paper establishes a theoretical and empirical basis that shows the impact of marketing communications and price promotion on brand equity. The theoretical review supports applying analysis techniques based on structural equations models to confirm empirically the relationship between marketing communication efforts and the dimensions of brand equity: perceived quality, brand loyalty, brand awareness and brand image. This measurement model is verified on a sample group of families which purchased durable goods — in this case a washing machine. The results indicate the positive effect of marketing communication on brand equity, and offer strong support for the measures of perceived quality, brand loyalty, brand awareness and brand image as antecedents of brand equity.
TL;DR: This work provides evidence that one mechanism responsible for TAR is RNAP‐mediated replication impairment, and using novel plasmid‐borne recombination constructs in Saccharomyces cerevisiae shows that RNA polymerase II (RNAPII) transcription induces recombination by impairing replication fork progression.
Abstract: Homologous recombination safeguards genome integrity, but it can also cause genome instability of important consequences for cell proliferation and organism development. Transcription induces recombination, as shown in prokaryotes and eukaryotes for both spontaneous and developmentally regulated events such as those responsible for immunoglobulin class switching. Deciphering the molecular basis of transcription-associated recombination (TAR) is important in understanding genome instability. Using novel plasmid-borne recombination constructs in Saccharomyces cerevisiae, we show that RNA polymerase II (RNAPII) transcription induces recombination by impairing replication fork progression. RNAPII transcription concomitant to head-on oncoming replication causes a replication fork pause (RFP) that is linked to a significant increase in recombination. However, transcription that is codirectional with replication has little effect on replication fork progression and recombination. Transcription occurring in the absence of replication does not affect either recombination or replication fork progression. The Rrm3 helicase, which is required for replication fork progression through nucleoprotein complexes, facilitates replication through the transcription-dependent RFP site and reduces recombination. Therefore, our work provides evidence that one mechanism responsible for TAR is RNAP-mediated replication impairment.
TL;DR: Rh(I) mono- and biscarbenes from imidazo[1,5-a]pyridin-3-ylidenes (ImPy) and derivatives such as 13 from a mesoionic carbene were synthesized and characterized.
Abstract: The imidazo[1,5-a]pyridine skeleton provides a versatile platform for the generation of new types of stable N-heterocyclic carbenes. Rh(I) mono- (6) and biscarbenes (7) from imidazo[1,5-a]pyridin-3-ylidenes (ImPy) and derivatives such as 13 from a mesoionic carbene were synthesized and characterized.
TL;DR: In this paper, the authors used Homogeneity Analysis and Multiple Linear Regression (SPSS 11) to predict teacher burnout in the province of Seville (Spain) using self-applied interviews and the Maslach Burnout Inventory (MBI).
TL;DR: The results show that the area near the mouth of the Huelva estuary is where the highest metal concentrations are found in sediments and in the two bivalve species, including Donax trunculus and C. gallina.
TL;DR: This study investigates the intellectual structure that serves as a basis for the IM research, identifying the main research trends used in the most relevant IM journals and analyzing their dissemination within those journals.
TL;DR: The results obtained shown that lightness (L) was significantly correlated with S, Ca, Fe, As, Pb, and Cd for the dark honey types (avocado, heather, chestnut, and honeydew).
Abstract: The mineral content and color characteristics of 77 honey samples were analyzed. Eighteen minerals were quantified for each honey. Multiple linear regression (MLR) was used to establish equations relating the colorimetric CIELAB coordinates to the mineral data. The results obtained shown that lightness (L*) was significantly correlated with S, Ca, Fe, As, Pb, and Cd for the dark honey types (avocado, heather, chestnut, and honeydew). For the light and brown honey types (citrus, rosemary, lavender, eucalyptus, and thyme), Cab* and b* showed the lower correlation with the mineral content of the honeys; their regression functions involve a few independent variables (Mg and Al for b* and only Al for Cab*). Furthermore, by means of application of linear discriminant analysis to the mineral content, it was possible to obtain a model that classifies the honeys by their lightness. The prediction ability of the built model, determined with the test set method, was 85%. Keywords: ICP−OES; minerals; honey; color; mu...
TL;DR: In this article, the deformation data for superplastic yttria-stabilized zirconia polycrystals with grain size 0.10 wt% over the entire stress range is available.
Abstract: Available deformation data for superplastic yttria-stabilized zirconia polycrystals with grain size 0.10 wt%) over the entire stress range. The strain-rate enhancement with respect to high-purity materials is related to the grain-boundary amorphous phase present in such materials.
TL;DR: The best-grouped honeys were those from heather; eucalyptus honeys formed a more dispersed group and finally orange-blossom and rosemary honeys form a less distinguishable group.
TL;DR: Participants at this unique consensus meeting attempted to define and spearhead an approach to increase awareness of the risks of TBI-induced endocrinopathies, in particular growth hormone deficiency (GHD), and to outline necessary and practical objectives for managing this condition.
Abstract: Primary objective: The goal of this consensus statement is to increase awareness among endocrinologists and physicians treating patients with traumatic brain injury (TBI) of the incidence and risks...
TL;DR: The findings of the present investigation show that microcystins induce oxidative stress in a time-dependent manner and that the type of administration of the cyanobacterial cells influences the extent of these effects.
13 Jun 2005
TL;DR: In this article, the authors demonstrate the potential of sub-wavelength resonators, namely, split-ring resonators and complementary split ring resonators to suppress undesired spurious bands in microwave filters, a key aspect to improve their rejection bandwidths.
Abstract: The main aim of this paper is to demonstrate the potentiality of sub-wavelength resonators, namely, split-ring resonators, complementary split-ring resonators, and related structures to the suppression of undesired spurious bands in microwave filters, a key aspect to improve their rejection bandwidths. The main relevant characteristics of the cited resonators are their dimensions (which can be much smaller than signal wavelength at resonance) and their high-Q factor. This allows us to design stopband structures with significant rejection levels, few stages, and small dimensions, which can be integrated within the filter active region. By this means, no extra area is added to the device, while the passband of interest is virtually unaltered. A wide variety of bandpass filters, implemented in both coplanar-waveguide and microstrip technologies, have been designed and fabricated by the authors. The characterization of these devices points out the efficiency of the proposed approach to improve filter responses with harmonic rejection levels near 40 dB in some cases. It is also important to highlight that the conventional design methodology for the filters holds. For certain configurations, the presence of the resonators slightly lowers the phase velocity at the frequencies of interest with the added advantage of some level of reduction in device dimensions.
TL;DR: The results from the analysis of the measurement and structural model support the reliability and validity of the European Excellence Model as a reference framework for the implementation, evaluation and improvement of quality in the area of higher education.
Abstract: In the literature on quality management it is necessary to undertake empirical studies that go further into the knowledge and understanding of the relationships between the key implementation factors and the results. This work falls within that context and its reference is the EFQM Excellence Model and the field of higher education. The structural equations method is used and, more specifically, the Partial Least Squares (PLS) technique. The results from the analysis of the measurement and structural model support the reliability and validity of the European Excellence Model as a reference framework for the implementation, evaluation and improvement of quality in the area of higher education. The need to consider the agents together as the determinants of the results is also revealed, as well as there being an internal logic that connects the model's results. Moreover, the analysis has allowed us to conduct an in-depth study of the causal structure of the EFQM Model. An understanding of this stru...
TL;DR: In this article, a comparative study of the antioxidant activity of wine phenolics has been performed, including benzoic and cinnamic acids, flavanols, flavonols and resveratrol.