Showing papers by "Spanish National Research Council published in 1995"
TL;DR: Submerged vegetation respond to increased nutrient loading through a shift from slow-growing seagrasses and large Macroalgae to fast-growing macroalgae, and the ultimate dominance of phytoplankton at high nutrient loadings, which reflects a change from nutrient to light limitation along the eutrophication gradient.
Abstract: Submerged vegetation respond to increased nutrient loading through a shift from slow-growing seagrasses and large macroalgae to fast-growing macroalgae, and the ultimate dominance of phytoplankton at high nutrient loadings. This shift reflects a change from nutrient to light limitation along the eutrophication gradient. Slow-growing seagrasses and large macroalgae are good competitors when nutrients are limiting because they have relatively low nutrient requirements, are able of efficient internal nutrient recycling, and can access the elevated nutrient pools in the sediment. Fast-growing macroalgae and phytoplankton are superior competitors when light is limiting because they are positioned closer to the water surface, and capture and use light more efficiently. The important ecosystem consequences of altered nutrient regimes derive from the shift in dominant vegetation types. Slow-growing seagrasses and large macroalgae are longevous, decompose slowly, and experience only moderate grazing losse...
896 citations
TL;DR: It is shown that free-living elderly Europeans, regardless of geographical location, are at substantial risk of inadequate vitamin D status during winter and that dietary enrichment or supplementation with vitamin D should be seriously considered during this season.
788 citations
TL;DR: In this article, a measure of complexity based on a probabilistic description of physical systems is proposed, which can be applied to many physical situations and to different descriptions of a given system.
756 citations
710 citations
TL;DR: Results obtained suggest that in the cellular toxicity of NaCl in pea plants, superoxide- and H 2 O 2 -mediated oxidative damage in chloroplasts may play an important role.
694 citations
TL;DR: In this article, it has been shown that the intrinsic activity of MCM-41 is lower than Ti-Beta and TS-1 when using H2O2 as oxidant.
614 citations
TL;DR: In this article, a review summarizes published data on catalytic performances of different vanadium-containing oxides, including unsupported and supported V2O5, vanadates, solid solutions and mixed phases, in the oxidative dehydrogenation of C2-C5 alkanes.
Abstract: This review summarizes published data on catalytic performances of different vanadium-containing oxides, including unsupported and supported V2O5, vanadates, solid solutions and mixed phases, in the oxidative dehydrogenation of C2–C5 alkanes. The analysis of the structure-activity relationships shows that various species characterized by a different reactivity exist on the surface of these catalysts. There are some indications that tetrahedral vanadium species are the most favourable for alkane oxidehydrogenation. Its intrinsic activity seems to be largely dependent on the structure of the nearest surrounding and, therefore, can be modified by changing the nature and number of the neighbouring ions. Although the reaction mechanism is generally accepted to be through the redox cycle between V5+ and V4+, opposite relationships between catalyst activity/selectivity and reducibility have been established, even for the same catalytic systems. No clear interpretation regarding the mode of alkane activation can be derived from a survey of the literature. This and some other aspects of the reaction mechanism need further studies at a molecular level.
599 citations
TL;DR: In this article, the role of anhydrite (CaSO4) in the sorption of trace elements such as As, B, Ge, Se, Pb, Mo, Zn and Tl from flue gas and in the reduction of emissions of potentially toxic elements was investigated.
544 citations
TL;DR: Immunoblots show that GLYT1 is expressed at the highest concentrations in the spinal cord, brainstem, diencephalon, and retina, and, in a lesser degree, to the olfactory bulb and brain hemispheres, whereas it is not detected in peripheral tissues.
Abstract: Glycine is the major inhibitory neurotransmitter in the spinal cord and brainstem and is also required for the activation of NMDA receptors. The extracellular concentration of this neuroactive amino acid is regulated by at least two glycine transporters (GLYT1 and GLYT2). To study the localization and properties of these proteins, sequence- specific antibodies against the cloned glycine transporters have been raised. Immunoblots show that the 50–70 kDa band corresponding to GLYT1 is expressed at the highest concentrations in the spinal cord, brainstem, diencephalon, and retina, and, in a lesser degree, to the olfactory bulb and brain hemispheres, whereas it is not detected in peripheral tissues. Pre-embedding light and electron microscopic immunocytochemistry show that GLYT1 is expressed in glial cells around both glycinergic and nonglycinergic neurons except in the retina, where it is expressed by amacrine neurons, but not by glia. The expression of a 90–110 kDa band corresponding to GLYT2 is restricted to the spinal cord, brain-stem, and cerebellum; in addition, very low levels occur in the diencephalon. GLYT2 is found in presynaptic elements of neurons thought to be glycinergic. However, in the cerebellum, GLYT2 is expressed both in terminal boutons and in glial elements. The physiological consequences of the regional and cellular distributions of these two proteins as well as the possibility of the existence of an unidentified neuronal form of GLYT1 are discussed.
520 citations
TL;DR: In this article, the structures and relative stabilities of several CeO2 surfaces, and of anion vacancy centers formed on them, were studied using theoretical molecular mechanics methods, and it was shown that the compact (111) surface appears as the most stable one; it is followed by (110), (211) and (100).
477 citations
TL;DR: In this paper, the photocatalytic degradation of malic acid was investigated on several rigid substrates, including glass and stainless steel, and the resulting materials have been characterized by XPS, SEM/EDX, XRD and UV-vis absorption spectroscopy.
Abstract: In the present study TiO 2 has been supported on several rigid substrates. Deposition on glass and quartz was carried out by a dip coating procedure and the deposition on stainless steel by an electrophoretic deposition process. The resulting materials have been characterized by XPS, SEM/EDX, XRD and UV-vis absorption spectroscopy. The materials were then tested for the photocatalytic degradation of malic acid. For this reaction, the sample supported on quartz showed the highest catalytic activity. The photocatalytic activity pattern as a function of the nature of the support (fused silica, glass, stainless steel) followed the decreasing order: TiO 2 /quartz > TiO 2 /steel ≈ TiO 2 /glassaphotolysis. This decline in activity has been correlated with the presence of cationic impurities (Si 4+ , Na + , Cr 3+ , Fe 3+ ) in the layer as a consequence of the necessary thermal treatments to improve the cohesion of the titania layer and its adhesion onto the support.
TL;DR: Analysis of the complete genome of African swine fever virus (ASFV) strain BA71V confirms the intermediate characteristics of ASFV between poxviruses and iridoviruses, supporting the notion that AsFV belongs to an independent virus family.
TL;DR: This ELISPOT assay can be performed with spleen cells from immunized mice, and provide the precise number of antigen specific CD8+ T cells present in mixed lymphocyte populations, and is more sensitive than the chromium-51 release assay, and much simpler than the conventional precursor frequency analysis.
TL;DR: A family of new noncompetitive antagonists of AMPA receptors (GYKI 52466 and 53655) minimally affects kainate-induced responses at kainates receptors while completely blocking AMPA receptor-mediated currents, making it possible to separate the responses mediated by each receptor.
TL;DR: The MCM-41-based catalyst was seen to give superior HDS, HDN, and HC activities to the latter two catalysts in a one-stage operation using an untreated gasoil.
TL;DR: It is shown here that mutations in the minibrain (mnb) gene cause an abnormal spacing of neuroblasts in the outer proliferation center (opc) of larval brain, with the implication that mnb opc neuroblast produce less neuronal progeny than do wild type.
TL;DR: The results demonstrate that mycorrhizal hyphae can take up water and that there are considerable variations in both the behaviour of these two VAM fungi and in the mechanisms involved in their effects on plant water relations.
Abstract: Vesicular-arbuscular mycorrhizae may increase resistance of plants to drought by a number of mechanisms, such as increased root hydraulic conductivity, stomatal regulation, hyphal water uptake and osmotic adjustment. However, a substantial contribution of vesicular-arbuscular mycorrhizal (VAM) hyphae to water uptake has not been demonstrated unequivocally. The objective of this investigation was to examine the contribution of hyphae from two VAM fungi to water uptake and transport by the host plant. Lettuce (Lactuca saliva L.) plants were grown in a container divided by a screen into two compartments. One was occupied by roots, the other only by VAM hyphae, which the screen permitted to pass. Roots were colonized by the VAM fungi Glomus deserticola or Glomus fasciculatum, or were left uninoculated but P-supplemented. Water was supplied to the hyphal compartment at a distance of 10 cm from the screen (root). CO 2 exchange rate, water-use efficiency, transpiration, stomatal conductance and photosynthetic phosphorus-use efficiency of VAM or P-amended control plants were evaluated at three levels of water application in the hyphal compartment. Results indicate that much of the water was taken up by the hyphae in VAM plants. VAM plants, which had access to the hyphal compartment, had higher water and nutrient contents. G. deserticola functioned efficiently under water limitation and mycelium from G. fasciculatum-colonized plants was very sensitive to water in the medium. This discrepancy in VAM behaviour reflects the various abilities of each fungus according to soil water levels. Different abilities of specific mycelia were also expressed in terms of nutritional and leaf gas-exchange parameters. G. fasciculatum caused a significant increase in net photosynthesis and rate of water use efficiency compared to G. deserticola and P-fertilized plants. In contrast, the G. deserticola treatment was the most efficient affecting N, P and K nutrition, leaf conductance and transpiration. Since no differences in the intra- and extra-radical hyphal extension of the two endophytes were found, the results demonstrate that mycorrhizal hyphae can take up water and that there are considerable variations in both the behaviour of these two VAM fungi and in the mechanisms involved in their effects on plant water relations.
TL;DR: In this paper, the maximum penetration of localized attack on steel embedded in concrete containing chlorides was found to be about four to eight times the average general penetration of the deepest pits.
TL;DR: It is observed that nitric oxide release prevents the drop in the expression of the protooncogene bcl-2, both at the mRNA and protein levels, suggesting the existence of an unknown pathway that links nitricoxide signaling with Bcl-1 expression.
Abstract: Incubation of ex vivo cultured mature B cells in the presence of nitric oxide or nitric oxide-donor substances delays programmed cell death as determined by the appearance of DNA laddering in agarose gel electrophoresis or by flow-cytometry analysis of DNA. Nitric oxide also rescues B cells from antigen-induced apoptosis but fails to provide a co-stimulatory signal that converts the signal elicited by the antigen into a proliferative response. The protective effects of nitric oxide against programmed cell death can be reproduced by treatment of the cells with permeant analogues of cyclic GMP. Regarding the mechanisms by which nitric oxide prevents apoptosis in B cells, we have observed that nitric oxide release prevents the drop in the expression of the protooncogene bcl-2, both at the mRNA and protein levels, suggesting the existence of an unknown pathway that links nitric oxide signaling with Bcl-2 expression.
TL;DR: In this paper, the authors reported the discovery of a brown dwarf near the centre of the Pleiades star cluster, whose luminosity and temperature are so low that its mass must be less than 0.08 solar masses, the accepted lower limit on the mass of a true star.
Abstract: BROWN dwarfs are cool star-like objects that have insufficient mass to maintain stable nuclear fusion in their interiors. Although brown dwarfs are not stars, they are expected to form in the same way, and their frequency of occurrence should reflect the trends seen in the birthrates of low-mass stars. But finding brown dwarfs has proved to be difficult, because of their low intrinsic luminosity. The nearby Pleiades star cluster is widely recognized as a likely host for detectable brown dwarfs because of its young age — the still-contracting brown dwarfs should radiate a large fraction of their gravitational energy at near-infrared wavelengths. Here we report the discovery of a brown dwarf near the centre of the Pleiades. The luminosity and temperature of this object are so low that its mass must be less than 0.08 solar masses, the accepted lower limit on the mass of a true star1–3. The detection of only one brown dwarf within our survey area is consistent with a smooth extrapolation of the stellar mass function of the Pleiades4, suggesting that brown dwarfs, although probably quite numerous in the Galactic disk, are unlikely to comprise more than ˜1% of its mass.
TL;DR: In this paper, the mass of the lightest Higgs boson in the Minimal Supersymmetric Standard Model was derived in a model-independent way, including leading and next-to-leading order (two-loop) radiative corrections.
TL;DR: In this article, an optimized hydrotalcite showed excellent catalytic properties for the synthesis of 2′,4,4′-trimethoxychalcone (Vesidryl), a product of pharmacological interest.
TL;DR: In this paper, the authors re-examine the lower bound on the mass of the Higgs boson, Mh, from standard model stability including next-to-leading-log radiative corrections, and show that the bound is O (10 GeV) less stringent than in previous estimates.
TL;DR: In this paper, XPS and Factor Analysis (FA) were applied to characterize the surface state of three polycrystalline cobalt oxide samples with different crystallographic bulk structure (CO 3 O 4 and CoO) and surface characteristics.
TL;DR: It is shown that LOV-induced apoptosis is associated with intracellular acidification and that activation of the Na+/H+ antiporter induces a raise in pH which is sufficient to prevent or arrest DNA digestion.
Woods Hole Oceanographic Institution1, Freiberg University of Mining and Technology2, Texas A&M University3, University of Michigan4, University of Miami5, Spanish National Research Council6, Max Planck Society7, Kyushu University8, IFREMER9, University of Tasmania10, Columbia University11, Geological Survey of Canada12, Stockholm University13, University of Strasbourg14, Cardiff University15, National Institute of Advanced Industrial Science and Technology16, Indiana University17, Rutgers University18, University of Houston19, University of San Diego20, University of California, Santa Cruz21
TL;DR: In this article, the authors report results obtained from drilling a series of holes into an actively forming sulphide deposit on the Mid-Atlantic Ridge, and demonstrate the importance of anhydrite in the growth of massive sulphide deposits, despite its absence in those preserved on land.
Abstract: THE hydrothermal circulation of sea water through permeable ocean crust results in rock–water interactions that lead to the formation of massive sulphide deposits. These are the modern analogues of many ancient ophiolite-hosted deposits1–4, such as those exposed in Cyprus. Here we report results obtained from drilling a series of holes into an actively forming sulphide deposit on the Mid-Atlantic Ridge. A complex assemblage of sulphide–anhydrite–silica breccias provides striking evidence that such hydrothermal mounds do not grow simply by the accumulation of sulphides on the sea floor. Indeed, the deposit grows largely as an in situ breccia pile, as successive episodes of hydrothermal activity each form new hydrothermal precipitates and cement earlier deposits. During inactive periods, the collapse of sulphide chimneys, dissolution of anhydrite, and disruption by faulting cause brecciation of the deposit. The abundance of anhydrite beneath the present region of focused hydrothermal venting reflects the high temperatures ( > 150 °C) currently maintained within the mound, and implies substantial entrainment of cold sea water into the interior of the deposit. These observations demonstrate the important role of anhydrite in the growth of massive sulphide deposits, despite its absence in those preserved on land.
TL;DR: It is shown here that MAPK and MEK are activated in vivo by an active mutant of zeta PKC, and that a kinase‐defective dominant negative mutant of zeppelin PKC dramatically impairs the activation of both MEK and MAPK by serum and tumour necrosis factor (TNF alpha).
Abstract: Protein kinase C zeta (zeta PKC) is critically involved in the control of a number of cell functions, including proliferation and nuclear factor kappa B (NF-kappa B) activation. Previous studies indicate that zeta PKC is an important step downstream of Ras in the mitogenic cascade. The stimulation of Ras initiates a kinase cascade that culminates in the activation of MAP kinase (MAPK), which is required for cell growth. MAPK is activated by phosphorylation by another kinase named MAPK kinase (MEK), which is the substrate of a number of Ras-activated serine/threonine kinases such as c-Raf-1 and B-Raf. We show here that MAPK and MEK are activated in vivo by an active mutant of zeta PKC, and that a kinase-defective dominant negative mutant of zeta PKC dramatically impairs the activation of both MEK and MAPK by serum and tumour necrosis factor (TNF alpha). The stimulation of other kinases, such as stress-activated protein kinase (SAPK) or p70S6K, is shown here to be independent of zeta PKC. The importance of MEK/MAPK in the signalling mechanisms activated by zeta PKC was addressed by using the activation of a kappa B-dependent promoter as a biological read-out of zeta PKC.
TL;DR: De la Fuente et al. as discussed by the authors found that disparities in the stocks of human and public capital account for a third of observed regional inequality, about evenly split between the two factors.
Abstract: Regional policy and Spain
infrastructure and education as instruments of regional policy: evidence from Spain
Governments have often tried to influence the regional distribution of economic activity through supply-side measures such as investment in training and infrastructure. Using evidence from Spain, we examine whether such policies can have an impact and whether they have done so in the past.
Our results indicate that disparities in the stocks of human and public capital account for a third of observed regional inequality, about evenly split between the two factors. Hence public investment can in principle be used to reduce regional disparity. Its actual impact, however, will depend both on its overall volume and on the extent to which its regional allocation does indeed vary with regional need. In Spain, investment in infrastructure has made only a small contribution to regional convergence, primarily because it has not in practice been allocated to redistribute across regions to any great extent. In contrast, EFRD transfers have clearly been allocated among regions with redistribution in mind. The impact of the Fund has been significant, but it has been limited by the relatively small size of the programme.
— Angel de la Fuente and Xavier Vives
TL;DR: The evidence suggests that ensheathing glia are unique, have their own identity, and do not belong to any previously described glial type.
Abstract: The olfactory bulb (OB) is a structure of the central nervous system (CNS) in which axonal growth occurs throughout the lifetime of the organism. A major difference between the OB and the remaining CNS is the presence of ensheathing glia in the first two layers of the OB. Ensheathing glia display properties that might be involved in the process of regeneration and they appear to be responsible for the permissibility of the adult OB to axonal growth. In fact, transplants of ensheathing glia can be used as promoters of axonal regeneration within the adult CNS. The axonal growth-promoting properties of ensheathing glia make the study of this cell type interesting for understanding the mechanisms underlying axonal regeneration. Several groups have studied OB ensheathing cells extensively in an attempt to classify them within any of the known glial groups. However, this cell type does not exhibit the phenotypic features of any glial population described thus far. In this article we review the characteristics that differentiate ensheathing glia from other peripheral and central glial populations as well as the properties that involve them in axonal regeneration. The evidence suggests that ensheathing glia are unique, have their own identity, and do not belong to any previously described glial type.
TL;DR: Within the framework of theories where both scalars and fermions are present, a systematic prescription for the construction of [ital CP]-violating quantities that are invariant under basis transformations of those matter fields is developed.
Abstract: Within the framework of theories where both scalars and fermions are present, we develop a systematic prescription for the construction of [ital CP]-violating quantities that are invariant under basis transformations of those matter fields. In theories with spontaneous symmetry breaking, the analysis involves the VEV transformation properties under a scalar basis change, with a considerable simplification of the study of [ital CP] violation in the scalar sector. These techniques are then applied in detail to the two-Higgs-doublet model with quarks. It is shown that there are new invariants involving scalar-fermion interactions, in addition to those already derived in previous analyses for the fermion-gauge and scalar-gauge sectors.