Showing papers by "University of Extremadura published in 2002"

Spatial/spectral endmember extraction by multidimensional morphological operations

Abstract: Spectral mixture analysis provides an efficient mechanism for the interpretation and classification of remotely sensed multidimensional imagery. It aims to identify a set of reference signatures (also known as endmembers) that can be used to model the reflectance spectrum at each pixel of the original image. Thus, the modeling is carried out as a linear combination of a finite number of ground components. Although spectral mixture models have proved to be appropriate for the purpose of large hyperspectral dataset subpixel analysis, few methods are available in the literature for the extraction of appropriate endmembers in spectral unmixing. Most approaches have been designed from a spectroscopic viewpoint and, thus, tend to neglect the existing spatial correlation between pixels. This paper presents a new automated method that performs unsupervised pixel purity determination and endmember extraction from multidimensional datasets; this is achieved by using both spatial and spectral information in a combined manner. The method is based on mathematical morphology, a classic image processing technique that can be applied to the spectral domain while being able to keep its spatial characteristics. The proposed methodology is evaluated through a specifically designed framework that uses both simulated and real hyperspectral data.

AUX1 Promotes Lateral Root Formation by Facilitating Indole-3-Acetic Acid Distribution between Sink and Source Tissues in the Arabidopsis Seedling

Abstract: Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between indole-3-acetic acid (IAA) source and sink tissues. Gas chromatography-selected reaction monitoring-mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

Biodiesel Fuels from Vegetable Oils: Transesterification of Cynara cardunculus L. Oils with Ethanol

Abstract: A study was made of the transesterification reaction of Cynara cardunculus L. oil by means of ethanol, using sodium hydroxide and potassium hydroxide as catalysts. The objective of the work was to ...

Atrial structure and fibres: morphologic bases of atrial conduction

Abstract: The relationship between anatomy and function has long been recognised. Understanding the gross structure, and the myoarchitecture, of the atriums is fundamental to investigations into the substrates and therapy of atrial fibrillation. Based primarily on our experience with normal human hearts, this review provides, firstly, a basis of comparison of gross structures as seen in the clinical situation, and in animals commonly used in experimental studies. Secondly, we discuss the general arrangement of myocardial fibres with respect to gross topography in the normal human heart. The right atrium is dominated by an extensive array of pectinate muscles within the extensive appendage, whereas the left atrium is relatively smooth-walled, with a much smaller tubular appendage. Myoarchitecture displays parallel alignment of fibres along distinct muscle bundles, such as the terminal crest and Bachmann's bundle. Within the smooth wall of the left atrium, there is a marked transmural change in the orientation of the muscular fibres. Abrupt changes in orientation, and mixed arrangements, are common between bundles. Other than Bachmann's bundle, the muscular bridges which provide interatrial connections, and connections between the left atrium and the coronary sinus and inferior caval vein, are highly variable. Inhomogeneities both in gross structure and myoarchitecture are common in the normal heart. These should be taken into account when investigating hearts from patients known to have had a history of arrhythmias, in devising computer models, or when refining diagnostic and therapeutic strategies.

Using Fractional Order Adjustment Rules and Fractional Order Reference Models in Model-Reference Adaptive Control

Abstract: This paper investigates the use of Fractional Order Calculus (FOC) inconventional Model Reference Adaptive Control (MRAC) systems. Twomodifications to the conventional MRAC are presented, i.e., the use offractional order parameter adjustment rule and the employment offractional order reference model. Through examples, benefits from theuse of FOC are illustrated together with some remarks for furtherresearch.

Catalytic ozonation of oxalic acid in an aqueous TiO2 slurry reactor

Abstract: The ozonation of oxalic acid has been carried out in an agitated slurry semibatch reactor where powdered TiO2 has been used as a catalyst. The presence of TiO2 catalyst significantly improved the ozonation rate of oxalic acid compared to the results from non-catalytic ozonation. For gas flow rates higher than 12 l h−1 and agitation speed above 100 rpm, the catalytic process rate was chemically controlled. The kinetic study led to a zero-order kinetics for both the non-catalytic and catalytic ozonations. These experimental findings were corroborated by a mechanism of reactions. This kinetics also supported experimental results at different temperatures, ozone partial pressure and mass of catalyst per slurry volume. At low gas flow rate, where both mass transfer and chemical reaction controlled the process rate, the external gas to liquid mass transfer coefficient was also determined.

Excessive exercise in anorexia nervosa and bulimia nervosa: relation to eating characteristics and general psychopathology.

Abstract: Objective Excessive exercise is a well-known phenomenon in anorexia nervosa, but less is known about its role in bulimia nervosa. In addition, there is little evidence regarding the psychopathological processes that might act as predisposing, triggering, or maintaining factors for such exercise. The present study examined the presence of excessive exercise in different women with eating disorders, and its psychopathological correlates. Methods Case notes from 63 anorexia nervosa and 61 bulimia nervosa patients were examined. Two-way multivariate analyses of variance (diagnosis × use of excessive exercise) were used to determine the impact of the two factors upon eating characteristics (EAT-40 and BITE) and psychopathological symptoms (SCL-90-R). Results While high levels of depression were more likely among all patients who used excessive exercise, levels of anxiety and somatization were particularly high only among those anorexics who exercised excessively. Discussion Possible explanatory models are advanced to account for this pattern of findings, focusing on the possible use of exercise as an affect regulation strategy among anorexia nervosa patients. Further research is suggested to test and develop this model, and possible clinical implications are outlined. © 2002 by Wiley Periodicals, Inc. Int J Eat Disord 31: 370–375, 2002.

Pharmacokinetics of losartan and its metabolite E-3174 in relation to the CYP2C9 genotype.

Abstract: Background And Aim Losartan is metabolized by polymorphic CYP2C9 to E-3174. Our aim was to evaluate the pharmacokinetics of losartan and E-3174 in relation to the CYP2C9 genotype. Methods A 50-mg oral dose of losartan was given to 22 Swedish volunteers with different CYP2C9 genotypes. Losartan and E-3174 were analyzed by HPLC in plasma and urine samples collected up to 24 hours after drug intake. Furthermore, losartan and E-3174 were analyzed in 8-hour urine samples collected from 17 Spanish subjects after a single oral dose of 25 mg losartan. Results The maximum plasma concentration of E-3174 was significantly (P < .05) lower in the CYP2C9*1/*3 (n = 5) and CYP2C9*2/*3 (n = 4) groups compared with the CYP2C9*1/*1 (n = 6) and CYP2C9*1/*2 (n = 3) groups and extremely low in 1 subject with the CYP2C9*3/*3 genotype. The ratio of the total losartan area under the plasma concentration–time curve (AUC) to the total E-3174 AUC (AUClosartan/AUCE-3174) was higher in the subject with the CYP2C9*3/*3 genotype (30-fold) and also in the CYP2C9*1/*3 and *2/*3 groups (approximately 2- and 3-fold, respectively) compared with the CYP2C9*1/*1 group. The plasma ratios correlated significantly with the 0- to 8-hour urinary losartan/E-3174 ratios. Among the total of 39 subjects, the urinary ratio was significantly higher in subjects with the CYP2C9*1/*3 (n = 10) and *2/*3 (n = 4) genotypes than in those with the CYP2C9*1/*1 genotype (n = 11; P < .01) and approximately 40-fold higher in subjects with the CYP2C9*3/*3 genotype (n = 3). Conclusion The CYP2C9*3 allele was shown to be associated with decreased formation of E-3174 from losartan. The significant differences between genotypes in plasma and urine losartan/E-3174 ratios and the good correlation between the plasma and urine ratios suggest that the losartan/E-3174 ratio in 0- to 8-hour urine specimens may serve as a phenotyping assay for CYP2C9 activity. Further studies in larger populations will be required to establish this. Clinical Pharmacology & Therapeutics (2002) 71, 89–98; doi: 10.1067/mcp.2002.121216

Overview: Damage in brittle layer structures from concentrated loads

Abstract: In this article, we review recent advances in the understanding and analysis of damage initiation and evolution in laminate structures with brittle outerlayers and compliant sublayers in concentrated loading. The relevance of such damage to lifetime-limiting failures of engineering and biomechanical layer systems is emphasized. We describe the results of contact studies on monolayer, bilayer, trilayer, and multilayer test specimens that enable simple elucidation of fundamental damage mechanics and yet simulate essential function in a wide range of practical structures. Damage processes are observed using post mortem (“bonded-interface”) sectioning and direct in situ viewing during loading. The observations reveal a competition between damage modes in the brittle outerlayers—cone cracks or quasiplasticity at the top (near-contact) surfaces and laterally extending radial cracks at the lower surfaces. In metal or polymeric support layers, yield or viscoelasticity can become limiting factors. Analytical relations for the critical loads to initiate each damage mode are presented in terms of key system variables: geometrical (layer thickness and indenter radius); material (elastic modulus, strength and toughness of brittle components, hardness of deformable components). Such relations provide a sound physical basis for the design of brittle layer systems with optimal damage thresholds. Other elements of the damage process—damage evolution to failure, crack kinetics (and fatigue), flaw statistics, and complex (tangential) loading—are also considered.

Kinetics of Heterogeneous Catalytic Ozone Decomposition in Water on an Activated Carbon

Abstract: Ozone decomposition in water in the presence of an activated carbon has been studied. Variables investigated were agitation speed, carbon particle size, temperature and pH. In all cases, the presence of activated carbon improved the ozone decomposition rate. Between pH 2 and 7 the ozone decomposition rate due to both the homogeneous and heterogeneous mechanisms hardly varied while a significant increase was noticed with increasing pH. A kinetic study based on a Langmuir-Hinselwood type mechanism for the heterogeneous surface reaction was undertaken. According to this mechanism the heterogeneous ozone decomposition kinetics can be simplified to follow a first order process. Fit of experimental results to the kinetic equations derived from the mechanism allowed for the determination of the apparent first order rate constants of the ozone surface heterogeneous reaction and adsorption equilibrium constants.

Kinetics of Catalytic Ozonation of Oxalic Acid in Water with Activated Carbon

Abstract: The ozonation kinetics of oxalic acid in water in the presence of an activated carbon has been investigated at acid pH. The presence of the activated carbon significantly enhances the degradation rate of oxalic acid if compared to single ozonation and single adsorption. According to total organic carbon measurements, nearly complete mineralization of oxalic acid can be achieved depending on the experimental conditions. The presence of tert-butyl alcohol, which scarcely adsorbs on the carbon surface at the conditions investigated, led to a significant reduction of the oxalic acid removal rate. Consequently, experimental results suggest that the reaction proceeds in the water phase between oxalic acid and oxidant species, likely hydroxyl radicals, coming from the ozone decomposition on the carbon surface. The proposed mechanism yielded a first-order kinetics with respect to ozone, close to the 0.8 order experimentally observed. Also, the energy of activation was found to be approximately 15 kcal mol-1.

Characterization of the most odor-active compounds of Iberian ham headspace.

Abstract: Gas chromatography-olfactometry (GC-O) based on detection frequency (DF) was used to characterize the most odor-active compounds from the headspace of Iberian ham. Twenty-eight odorants were identified by GC-O on two capillary columns, including aldehydes (11), sulfur-containing compounds (7), ketones (5), nitrogen-containing compounds (2), esters (2), and an alcohol. Among them, the highest odor potencies (DF values) were found for 2-methyl-3-furanthiol, 2-heptanone, 3-methylbutanal, methanethiol, hexanal, hydrogen sulfide, 1-penten-3-one, 2-methylpropanal, ethyl 2-methylbutyrate, and (E)-2-hexenal. Nine of the 28 most odor-active compounds were identified for the first time as aroma components of dry-cured ham, including hydrogen sulfide, 1-penten-3-one, (Z)-3-hexenal, 1-octen-3-one, and the meaty-smelling compounds 2-methyl-3-furanthiol, 2-furfurylthiol, 3-mercapto-2-pentanone, 2-acetyl-1-pyrroline, and 2-propionyl-1-pyrroline.

Cork Taint of Wines: Role of the Filamentous Fungi Isolated from Cork in the Formation of 2,4,6-Trichloroanisole by O Methylation of 2,4,6-Trichlorophenol

Abstract: Cork taint is a musty or moldy off-odor in wine mainly caused by 2,4,6-trichloroanisole (2,4,6-TCA). We examined the role of 14 fungal strains isolated from cork samples in the production of 2,4,6-TCA by O methylation of 2,4,6-trichlorophenol (2,4,6-TCP). The fungal strains isolated belong to the genera Penicillium (four isolates); Trichoderma (two isolates); and Acremonium, Chrysonilia, Cladosporium, Fusarium, Mortierella, Mucor, Paecilomyces, and Verticillium (one isolate each). Eleven of these strains could produce 2,4,6-TCA when they were grown directly on cork in the presence of 2,4,6-TCP. The highest levels of bioconversion were carried out by the Trichoderma and Fusarium strains. One strain of Trichoderma longibrachiatum could also efficiently produce 2,4,6-TCA in liquid medium. However, no detectable levels of 2,4,6-TCA production by this strain could be detected on cork when putative precursors other than 2,4,6-TCP, including several anisoles, dichlorophenols, trichlorophenols, or other highly chlorinated compounds, were tested. Time course expression studies with liquid cultures showed that the formation of 2,4,6-TCA was not affected by a high concentration of glucose (2% or 111 mM) or by ammonium salts at concentrations up to 60 mM. In T. longibrachiatum the O methylation of 2,4,6-TCP was catalyzed by a mycelium-associated S-adenosyl-l-methionine (SAM)-dependent methyltransferase that was strongly induced by 2,4,6-TCP. The reaction was inhibited by S-adenosyl-l-homocysteine, an inhibitor of SAM-dependent methylation, suggesting that SAM is the natural methyl donor. These findings increase our understanding of the mechanism underlying the origin of 2,4,6-TCA on cork, which is poorly understood despite its great economic importance for the wine industry, and they could also help us improve our knowledge about the biodegradation and detoxification processes associated with chlorinated phenols.

CYP3A4 variant alleles in white individuals with low CYP3A4 enzyme activity.

Abstract: Objective Our objective was to evaluate the presence of CYP3A4 gene variants in white individualswith low CYP3A4 enzyme activity. Methods Persons with extremely low enzyme activity, either in vitro or in vivo, were selected in a panel of 97 healthy subjects. Genetic analyses for CYP3A4 variant alleles present in white subjects, including CYP3A4*1B, CYP3A4*2, CYP3A4*4, CYP3A4*5, CYP3A4*6, CYP3A4*8, CYP3A4*11, CYP3A4*12, and CYP3A4*13, were performed on genomic deoxyribonucleic acid from these subjects by amplification-restriction and sequencing. Results With the exception of CYP3A4*1B, none of the variant alleles analyzed were present in30 genes from persons with extremely low enzyme activity. CYP3A4*1B was present in the population studied with an allele frequency of 5.5%. Nevertheless, the presence of CYP3A4*1B does not correlate with low enzyme activity, either in vivo or in vitro, in either heterozygosity or homozygosity. CYP3A4*2 was not identified in 290 genes from Spanish persons or in 70 genes from Finnish persons. Conclusions Although the genetic component of the interindividual variability of CYP3A4 enzyme activity seems to be high, our findings do not support a key role for the variant alleles analyzed on the majority of white persons with low CYP3A4 activity. This suggests the occurrence of as yet unknown mutations that affect CYP3A4 orother functionally related genes. Clinical Pharmacology & Therapeutics (2002) 71, 196–204; doi: 10.1067/mcp.2002.121371

The terminal crest: morphological features relevant to electrophysiology

Abstract: Objective: To investigate the detailed anatomy of the terminal crest (crista terminalis) and its junctional regions with the pectinate muscles and intercaval area to provide the yardstick for structural normality. Design: 97 human necropsy hearts were studied from patients who were not known to have medical histories of atrial arrhythmias. The dimensions of the terminal crest were measured in width and thickness from epicardium to endocardium, at the four points known to be chosen as sites of ablation. Results: The pectinate muscles originating from the crest and extending along the wall of the appendage towards the vestibule of the tricuspid valve had a non-uniform trabecular pattern in 80% of hearts. Fine structure of the terminal crest studied using light and scanning electron microscopy consisted of much thicker and more numerous fibrous sheaths of endomysium with increasing age of the patient. 36 specimens of 45 (80%) specimens studied by electron microscopy had a predominantly uniform longitudinal arrangement of myocardial fibres within the terminal crest. In contrast, in all specimens, the junctional areas of the terminal crest with the pectinate muscles and with the intercaval area had crossing and non-uniform architecture of myofibres. Conclusions: The normal anatomy of the muscle fibres and connective tissue in the junctional area of the terminal crest/pectinate muscles and terminal crest/intercaval bundle favours non-uniform anisotropic properties.

Odor-active compounds of Iberian hams with different aroma characteristics.

Abstract: The odor-active compounds of different commercial types of Iberian hams (Montanera and Pienso) were researched by gas chromatography-olfactometry based on a detection frequency method. The hams (long- and short-Montanera and Pienso Iberian hams) showed different sensory profiles, differences being significant for Montanera ham typical odor, aroma intensity and persistence, and cured and moldy aroma. Significant differences were also found for some odorants. The largest differences appeared in 2-acetyl-1-pyrroline, hexanal, (Z)-3-hexenal, ethyl 2-methylbutyrate, (E)-2-hexenal, 1-octen-3-one, 1-octen-3-ol, 2-propionyl-1-pyrroline, octanal, and an unknown odorant. Sensory characteristics and olfactometric profiles were significantly different between Montanera and Pienso hams. Significant differences also appeared between long- and short-Montanera hams, which shows great variability in this commercial type. Otherwise, the largest scores for moldy aroma in long-Montanera hams matched with the largest detection frequency of 1-octen-3-one and 1-octen-3-ol in this group.

Kinetic temperatures for a granular mixture

Abstract: An isolated mixture of smooth, inelastic hard spheres supports a homogeneous cooling state with different kinetic temperatures for each species This phenomenon is explored here by molecular dynamics simulation of a two component fluid, with comparison to predictions of the Enskog kinetic theory The ratio of kinetic temperatures is studied for two values of the restitution coefficient $\ensuremath{\alpha}=095$ and 080, as a function of mass ratio, size ratio, composition, and density Good agreement between theory and simulation is found for the lower densities and higher restitution coefficient; significant disagreement is observed otherwise The phenomenon of different temperatures is also discussed for driven systems, as occurs in recent experiments Differences between the freely cooling state and driven steady states are illustrated

Fate map of the chicken neural plate at stage 4.

Abstract: A detailed fate map was obtained for the early chick neural plate (stages 3d/4). Numerous overlapping plug grafts were performed upon New-cultured chick embryos, using fixable carboxyfluorescein diacetate succinimidyl ester to label donor chick tissue. The specimens were harvested 24 hours after grafting and reached in most cases stages 9-11 (early neural tube). The label was detected immunocytochemically in wholemounts, and cross-sections were later obtained. The positions of the graft-derived cells were classified first into sets of purely neural, purely non-neural and mixed grafts. Comparisons between these sets established the neural plate boundary at stages 3d/4. Further analysis categorized graft contributions to anteroposterior and dorsoventral subdivisions of the early neural tube, including data on the floor plate and the eye field. The rostral boundary of the neural plate was contained within the earliest expression domain of the Ganf gene, and the overall shape of the neural plate was contrasted and discussed with regard to the expression patterns of the genes Plato, Sox2, Otx2 and Dlx5 (and others reported in the literature) at stages 3d/4.