Showing papers by "Spanish National Research Council published in 1991"

Color-pigment correlation in virgin olive oil

Abstract: The chlorophyll and carotenoid content of virgin olive oils from five varieties harvested at varying degrees of ripeness were determined. Colors were evaluated from the chromatic ordinates L*, a*, b* of the absorption spectrum. Oil color changes for different varieties or stages of ripeness are directly related to pigment content and a* and b* values. The statistical study made on both series of parameters proves that there is a good correlation between them. The carotenoid content and b* have one of the best correlation coefficients (r) and is easily measured. This methodology evaluates chlorophyll and carotenoid content, an additional attribute for evaluation of virgin olive oil quality.

A Distance-Based Attribute Selection Measure for Decision Tree Induction

Abstract: This note introduces a new attribute selection measure for ID3-like inductive algorithms. This measure is based on a distance between partitions such that the selected attribute in a node induces the partition which is closest to the correct partition of the subset of training examples corresponding to this node. The relationship of this measure with Quinlan's information gain is also established. It is also formally proved that our distance is not biased towards attributes with large numbers of values. Experimental studies with this distance confirm previously reported results showing that the predictive accuracy of induced decision trees is not sensitive to the goodness of the attribute selection measure. However, this distance produces smaller trees than the gain ratio measure of Quinlan, especially in the case of data whose attributes have significantly different numbers of values.

Spatial and Temporal Patterns of Neurogenesis in the Chick Retina

Abstract: Chick embryo retinas were labelled in ovo by single injections of [3H]thymidine at selected times between days 2 and 12 of incubation. Embryos were later removed, at different stages of development, and the retinas processed for autoradiography of either serial sections or dissociated cell preparations. Analysis of unlabelled cells shows that neurogenesis starts, on day 2 of incubation, in a dorsotemporal area of the central retina, close to the posterior pole and to the optic nerve head. A gradient of neurogenesis spreads from this central area to the periphery, where neurogenesis ends, shortly after day 12, when the last few bipolar cells withdraw from the cell cycle. Additional dorsal-to-ventral and temporal-to-nasal gradients can be discerned in our autoradiographs. In all retinal sectors, ganglion cells start first to withdraw from the cell cycle, followed, with substantial overlapping, by amacrine, horizontal, photoreceptor plus Muller, and bipolar neuroblasts. Ganglion cells are also the first to reach the 50% level of unlabelled cells, followed this time by horizontal, photoreceptor, amacrine, Muller and bipolar cells. Finally, 100% levels of unlabelled cell populations are attained simultaneously by ganglion, horizontal and photoreceptor cells, followed by amacrine, then by Muller, and last by bipolar cells. Although all classes of neurons, in varying proportions, are being produced most of the time, our results also demonstrate that, in any given retinal area, the first cells leaving the cycle are determined to become ganglion cells, and the last ones bipolar cells, and not other types.

Protein-priming of DNA replication

Abstract: PERSPECTIVES AND SUMMARY . ....... . . . . . . . . . . . . ...... ... . . . . ... 40 ADENOVIRUS DNA REPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . �;;,t���:��� �� �:�:o:::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::::::: :: :::::::::: Viral Proteins Required for Replication . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . Cell�lar Protei�s Required for Replication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Repitcatwn OT/gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Replication of the Nontemplate Strand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BACTERIOPHAGE 4>29 DNA REPLICATION . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . .... ...... . . . . . Replication in Vivo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Replication in Vitro . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . Viral Proteins Essential for the Initiation of Replication . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . Other Viral Proteins Involved in Replication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Repitcatwn OT/gm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Replication of the Nontemplate Strand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BACTERIOPHAGE PRDI DNA REPLICATION ....... . . . . . ....... . . . . . . . .. . . . . . . . ... . .... . . . BACTERIOPHAGE Cp-l DNA REPLICATION . . . . . . . . . . . ...... ..... . . . ...... . . ... . BACTERIOPHAGE HB-3 TP .. . . . . . . . . . . . . . . . . . . . . ........ . . . . . . . . . . . . ....... .. . TERMINAL PROTEINS IN LINEAR PLASMIDS . . . . . . . . . . .... . .. . . . . . . . . . .... . . . . HEPADNAVIRUS TP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GENOME-LINKED PROTEINS OF RNA VIRUSES . . ....... . CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Atom- and field-state evolution in the Jaynes-Cummings model for large initial fields.

Abstract: An asymptotic result is derived for the Jaynes-Cummings model of a two-level atom interacting with a quantized single-mode field, which is valid when the field is initially in a coherent state with a large average photon number. It is shown that for certain initial atomic states the joint atom-field wave function factors into an atomic and a field part throughout the interaction, so that each system remains separately in a pure state. The atomic part of the wave function displays a crossing of trajectories in the atom Hilbert space that leads to a unique state for the atom, independent of its initial state, at a specific time to (equal to half the revival time). The field part of the wave function resembles a crescent squeezed state. The well-known collapses and revivals are investigated from this perspective. The collapse appears to be associated with a "measurement" of the initial state of the atom with the field as the measuring apparatus. The measurement is not complete for finite average photon number: the system is instead left in a coherent superposition of macroscopically distinct states. At the half-revival time to this superposition of states is entirely in the field part of the state vector, so that the (pure) state of the field at that time is of the form sometimes referred to as a "Schrodinger cat. " The revivals of the population inversion are seen to be entirely due to the fact that the linear superposition of the two macroscopically distinct field states is coherent (i.e., a pure state), as opposed to an incoherent mixture.

From genes to phenotype : dynamical systems and evolvability

Abstract: The advent of genetics as an autonomous field of inquiry is closely associated with the establishment of the concepts of genotype and phenotype (Sapp, 1983). Heritable variation is generated at the genotypic level. Mendelian laws specify how this variability is transmitted to the next generation while selection operates at the level of gene product, i.e., the phenotype, The definition of this conceptual genotype-phenotype dichotomy allowed, for example, the integration of Mendelian genetics and population dynamics; a powerful tool of analysis which has been at the core of the Neo-Darwinian Synthesis (e.g. Provine, 1971; Mayr & Provine, 1980). A consequence of the consolidation of this conceptual framework was the effective elimination of development from the corpus of theoretical evolutionary biology. In the theoretical scheme proposed by evolutionary genetics, development is the function that maps the genotype onto the phenotype. It is well known that, even at the lowest levels of protein transcription, the relationship genotype-phenotype is not one-to-one. At higher levels of interaction, such as morphological traits, the genotype-phenotype is more complex and non-linear. For such a reason, genetic theory has to postulate ad hoc properties, such as pleitropy, penetrance, covariance, etc. to deal with the non-linear interactions characteristic of developmental systems (Cheverud, 1984). This phenomenological treatment, although satisfactory when studying the dynamics of gene transmission and evolution, prevents the possibility of studying the role of development in evolution. These non-linear interactions at the molecular, cellular and tissue levels give a structure to developmental systems that may have important evolutionary consequences. In particular, I would like to review the mathematical properties of the genotype-phenotype mapping function, explore its emerging properties and relate them to the issue of opportunity and constraint in morphological evolution. I will conclude with a speculative hypothesis on the role of selection at the level of the dynamical properties of generative systems.

Hypotensive activity of fibroblast growth factor.

Abstract: Acidic and basic fibroblast growth factors (FGFs) are members of a family of proteins that are broad-spectrum mitogens, have diverse hormone-like activities, and function in tumorigenesis. FGF's ability to raise the concentration of intracellular calcium ion suggests that FGF could induce the synthesis of endothelium-derived relaxing factor (EDRF) and consequently vasodilation. Systemic administration of FGF decreased arterial blood pressure. This effect was mediated by EDRF and by adenosine triphosphate-sensitive potassium ion channels. The hypotensive effect of FGF was segregated from its mitogenic activity by protein engineering. These results extend the range of FGF autocrine activities and potential therapeutic applications, emphasize the role of endothelium as an arterial blood pressure--regulating organ, and provide insight on the structural basis of FGF functions.

Differential effects of clomipramine given locally or systemically on extracellular 5-hydroxytryptamine in raphe nuclei and frontal cortex. An in vivo brain microdialysis study.

Abstract: The antidepressant drug clomipramine (CIM) blocks 5-hydroxytryptamine (5-HT) uptake in vitro. Electrophysiological studies have shown that CIM also reduces the firing of serotonergic neurons in the dorsal raphe nucleus. In order to assess the effects of CIM on serotonergic transmission in vivo, the technique of intracerebral microdialysis was used. CIM was administered either through the dialysis probe or i. p., and dialysate 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) were determined in frontal cortex and/or raphe nuclei. In addition, the action of extracellular 5-HT in raphe nuclei on the release of 5-HT in frontal cortex was studied.

Selective interactions between different species of mycorrhizal fungi and Rhizobium meliloti strains, and their effects on growth, N2-fixation (15N) and nutrition of Medicago sativa L.

Abstract: summary Three isolates of vesicular-arbuscular (VA) mycorrhizal fungi, belonging to the species Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, G. fasciculatum (Taxter sensu Gerd.) Gerd, and Trappe, and G. caledonium (Nicol. and Gerd.) Trappe and Gerd, were inoculated in dual combinations with six strains of Rhizobium meliloti with the aim of testing these combinations for functional compatibility with their common host plant, the legume Medicago sativa L. Symbiotic efficiency (promotion of plant growth and N and P nutrition) was found to be dependent on the particular combination of Rhizobium strain and Glomus species indicating selective and specific compatibilities between strains and isolates of the two types of microsymbiont, but also between them and the common host plant. Observed effects on plant growth were in general, though not always, related to the extent of VA mycorrhizal colonization. Although the different mycorrhizal and/or rhizobial treatments produced different effects on plant growth, the rate of nodule formation on M. sativa roots remained constant. Most mycorrhizal treatments increased the concentration and/or content of N in plant shoots but effectiveness was in the order: G. fasciculatum > G. mosseae > G. caledonium. In some cases, this increase in N-content may be a consequence of a P-mediated stimulation of N2-fixation by VA mycorrhiza, as ascertained using 15N. In other instances, however, the increase seems to reflect a VA mycorrhizal-mediated enhancement of N-uptake from soil. VA mycorrhizal inoculation decreased the concentration of Ca and Mg in plant shoots and a buffering effect of VA mycorrhiza in situations of nutrient excess in soil is proposed.

Light scattering from random rough dielectric surfaces

Abstract: A theoretical and numerical study is made of the scattering of light and other electromagnetic waves from rough surfaces separating vacuum from a dielectric. The extinction theorem, both above and below the surface, is used to obtain the boundary values of the field and its normal derivative. Then we calculate the angular distribution of the ensemble average of intensity of the reflected and transmitted fields. The scattering equations are solved numerically by generating one-dimensional surface profiles through a Monte Carlo method. The effect of roughness σ and correlation distance T on the aforementioned angular distribution, as well as on the reflectance, is analyzed. Enhanced backscattering and new transmission effects are observed, also depending on the permittivity. The ratio σ/T is large in all cases studied, and thus no analytical approximation, such as the Kirchhoff approximation (KA) and small perturbation methods, could a priori be expected to hold. We find, however, that the range of validity of the KA can be much broader than that previously found in perfect conductors.

CAL1, a gene required for activity of chitin synthase 3 in Saccharomyces cerevisiae.

Abstract: The CAL1 gene was cloned by complementation of the defect in Calcofluor-resistant calR1 mutants of Saccharomyces cerevisiae. Transformation of the mutants with a plasmid carrying the appropriate insert restored Calcofluor sensitivity, wild-type chitin levels and normal spore maturation. Southern blots using the DNA fragment as a probe showed hybridization to a single locus. Allelic tests indicated that the cloned gene corresponded to the calR1 locus. The DNA insert contains a single open-reading frame encoding a protein of 1,099 amino acids with a molecular mass of 124 kD. The predicted amino acid sequence shows several regions of homology with those of chitin synthases 1 and 2 from S. cerevisiae and chitin synthase 1 from Candida albicans. calR1 mutants have been found to be defective in chitin synthase 3, a trypsin-independent synthase. Transformation of the mutants with a plasmid carrying CAL1 restored chitin synthase 3 activity; however, overexpression of the enzyme was not achieved even with a high copy number plasmid. Since Calcofluor-resistance mutations different from calR1 also result in reduced levels of chitin synthase 3, it is postulated that the products of some of these CAL genes may be limiting for expression of the enzymatic activity. Disruption of the CAL1 gene was not lethal, indicating that chitin synthase 3 is not an essential enzyme for S. cerevisiae.

40Ar/39Ar geochronology of Alpine tectonism in the Betic Cordilleras (southern Spain)

Abstract: The 40 Ar/ 39 Ar dating method has been applied to metamorphic rocks of the Alpujarride and Nevado-Filabride nappes (Alboran domain, SE Spain) in a first attempt to discriminate individual phases of deformation and metamorphism. The upper Nevado-Filabride nappes experienced an early eclogitic and blueschist metamorphism for which a barroisitic amphibole indicates a minimum age of 48 Ma. An Early Miocene age is attributed to the subsequent amphibolite facies metamorphism. Deformation associated with this metamorphic evolution is of unknown direction. The Alpujarride nappes record a plurifacial metamorphic evolution with the superimposition of low-pressure assemblages upon high-pressure ones with variable P – T ratios. Phengite from a carpholite-bearing high pressure-low temperature ( HP / LT ) assemblage gives an age of 25 Ma interpreted to reflect the end of the high-pressure evolution. Biotite and muscovite from high-grade metamorphic rocks overprinted under low-pressure conditions yield similar closure ages of 19 Ma dating cooling after the main episode of E – NE directed ductile deformation. This deformation was followed by W–SW directed extensional events producing brittle structures in the Alpujarride nappes and ductile-brittle shearing in the Nevado-Filabride nappes. Biotite and muscovite from ductile sheared rocks in the detachment zone between the two complexes have concordant ages of 16–17 Ma related to the end of the extensional ductile deformation. Therefore, a correlation of metamorphic and tectonic events between the two nappe complexes seems possible only since the Early Miocene and later.

Study on water extract of sewage sludge composts

Abstract: Quantitative changes in the components of the water extracts from the mixtures of sludge and organic residues during the composting and maturation processes were studied in order to identify parameters that can be used as indicators of compost maturity. The pH of the water extracts increased during the first 40 days of composting and then decreased. The EC increased in almost all the samples during composting. There was a significant decrease in the water soluble organic matter, water soluble C, organic N, and carbohydrate contents during composting and maturation. These processes were also responsible for a decrease in the amount of phytotoxic substances such as ammonium, phenols, and organic acids of low molecular weight. The organic matter content of the water extract, the water soluble carbon/water soluble nitrogen ratio, the sugar content and the biodegradability index can all be used as indices of maturity since, in addition to the decrease of the values with time, similar values were obtai...

Influence of sewage sludge application on crop yields and heavy metal availability

Abstract: A calcareous soil with a low content of organic matter was treated with aerobic or anaerobic sewage sludge. In the same way, chicken manure was used for comparison. Influences on crop yields and the supply of macronutrients and heavy metals to soil and plant tissues were studied. In the soil amended with the sludges the total N and extractable N and P contents increased, whereas the extractable K level remained nearly constant. Samples which had undergone a period of humification prior to sowing, mineralized part of their organic N and P during this period of time. Through sludge application, the levels of Cu, Zn, and Pb increased, the Fe content decreased while the extractability of Fe, Cu, Mn, Zn, and Pb increased as compared to the control. Sludge application enhanced the maize and barley yields as is the case of chicken manure. Sewage sludges supplied a considerable amount of available N to the plants, whereas the supply.of available K was low. In the barley plants it was observed that the hi...