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Showing papers by "University of Florence published in 1999"


Journal ArticleDOI
TL;DR: It is proposed that, above all in response to acute cadmium stress, various mechanisms might operate both in an additive and in a potentiating way, and a holistic and integrated approach seems to be necessary in the study of the response of higher plants to Cadmium.

2,189 citations


Journal ArticleDOI
TL;DR: Hyperquad simulation and speciation (HySS) as mentioned in this paper is a computer program written for the Windows operating system on personal computers which provides simulating titration curves and a system for providing speciation diagrams.

1,400 citations


Journal ArticleDOI
02 Apr 1999-Science
TL;DR: Transitions between quantum numbers M = -S and (S - n), with n even or odd, revealed a parity effect that is analogous to the suppression of tunneling predicted for half-integer spins, direct evidence of the topological part of the quantum spin phase (Berry phase) in a magnetic system.
Abstract: An experimental method based on the Landau-Zener model was developed to measure very small tunnel splittings in molecular clusters of eight iron atoms, which at low temperature behave like a nanomagnet with a spin ground state of S = 10. The observed oscillations of the tunnel splittings as a function of the magnetic field applied along the hard anisotropy axis are due to topological quantum interference of two tunnel paths of opposite windings. Transitions between quantum numbers M = -S and (S - n), with n even or odd, revealed a parity effect that is analogous to the suppression of tunneling predicted for half-integer spins. This observation is direct evidence of the topological part of the quantum spin phase (Berry phase) in a magnetic system.

1,179 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local universe.
Abstract: We use hard X-ray data for an "optimal" sample of Seyfert 2 galaxies to derive the distribution of the gaseous absorbing column densities among obscured active nuclei in the local universe. Of all Seyfert 2 galaxies in the sample, 75% are heavily obscured (NH > 1023 cm-2), and about half are Compton thick (NH > 1024 cm-2). Intermediate type 1.8-1.9 Seyfert galaxies are characterized by an average NH much lower than "strict" Seyfert 2 galaxies. No correlation is found between NH and the intrinsic luminosity of the nuclear source. This NH distribution has important consequences for the synthesis of the cosmic X-ray background. In addition, the large fraction of Compton-thick objects implies that most of the obscuring gas is located within a radius of a few 10 pc from the nucleus.

621 citations


Journal ArticleDOI
TL;DR: This paper refers mostly to conditions in the Mediterranean area and focuses on the progress achieved in the understanding of esca over the last few years, as well as the relations between esca and related syndromes or diseases.
Abstract: “Esca” disease of grapevine has long been known wherever grapes are grown. The disease may be as old as vine cultivation itself. References to esca-like symptoms are found in several ancient Greek and Latin works. Greater descriptive accuracy is found in medieval works such as the Kitab al-Felahah by Ibn al-Awam, a Spanish Muslim who lived in Seville at the end of the twelfth century, and the Opus Ruralium Commodorum by Pietro de’ Crescenzi, born around 1233 in Bologna. Esca is a Latin word meaning food, aliment, or, figuratively, bait. The name indirectly refers to the fruiting bodies of certain wood-rotting fungi. For example, Fomes, which in Latin means “tinder,” is the name of a genus of basidiomycetes once used to make a dry, easily ignited material suitable to start fires when using flints. Wood decayed by these fungi, including rotted grapevine wood, burned slowly and was used to keep fires aglow without a flame. Esca is a complex disease that comprises an array of symptoms, some of which have locally given their own names to the disease. For example in California, the dark, tiny spotting of the grapes is called “black measles.” In many grapevine-growing areas of the world, the sudden wilting of esca-affected vines in summer has earned this form of the disease the name “apoplexy.” Research on the etiology of esca, which started at the end of the nineteenth century in France, can be divided into three periods. The first period began in 1898 with Ravaz (61) and ended in 1926 with Viala (79). The overall conclusion of this period was that two basidiomycetous fungi, Stereum hirsutum (Willd.) Pers. and Phellinus (Fomes) igniarius (L.:Fr.) Quél., were the causal agents, although this could not be shown by pathogenicity tests. However, in Italy in 1912, Petri (58) successfully reproduced some early internal esca symptoms with two undetermined species of Cephalosporium and one of Acremonium that had also been associated with the disease. The second period in esca research started in California in 1957 with Hewitt (35) and lasted until 1959, when Chiarappa (9) detected the relationship between internal wood decay and black measles. He also showed how a Cephalosporium sp. reproduced in vivo some of the symptoms observed in the wood of diseased vines, and how P. igniarius caused wood decay in vitro. The third period, initiated by Larignon and Dubos in 1987 (39) and still underway, is directed at understanding the role of the mitosporic (asexually reproducing) fungi that act alone or together with the basidiomycetes to cause esca and related diseases. In the 1990s, studies on esca and its etiology have intensified. This came after a dramatic upsurge in the disease, especially in Germany, Italy, and Greece, where the arsenites, traditionally used to keep esca under control, have been banned and were replaced by less effective fungicides. However, even in France, Portugal, and Spain, where restricted use of sodium arsenite is still permitted, esca is widespread in all vine-growing regions. This paper refers mostly to conditions in the Mediterranean area and focuses on the progress achieved in our understanding of esca over the last few years. Reference is also made to a decline of young grapevines caused by some of the same mitosporic fungi as those commonly associated with esca in adult vines. Finally, the relations between esca and related syndromes or diseases are also discussed.

586 citations


Journal ArticleDOI
TL;DR: VEGF‐E is thus a potent angiogenic factor selectively binding to VEGF receptor‐2 alone can efficiently stimulate angiogenesis, and strongly indicates that activation of V EGF receptor-2 aloneCan efficiently stimulateAngiogenesis.
Abstract: The different members of the vascular endothelial growth factor (VEGF) family act as key regulators of endothelial cell function controlling vasculogenesis, angiogenesis, vascular permeability and endothelial cell survival. In this study, we have functionally characterized a novel member of the VEGF family, designated VEGF-E. VEGF-E sequences are encoded by the parapoxvirus Orf virus (OV). They carry the characteristic cysteine knot motif present in all mammalian VEGFs, while forming a microheterogenic group distinct from previously described members of this family. VEGF-E was expressed as the native protein in mammalian cells or as a recombinant protein in Escherichia coli and was shown to act as a heat-stable, secreted dimer. VEGF-E and VEGF-A were found to possess similar bioactivities, i.e. both factors stimulate the release of tissue factor (TF), the proliferation, chemotaxis and sprouting of cultured vascular endothelial cells in vitro and angiogenesis in vivo. Like VEGF-A, VEGF-E was found to bind with high affinity to VEGF receptor-2 (KDR) resulting in receptor autophosphorylation and a biphasic rise in free intracellular Ca2+ concentration, whilst in contrast to VEGF-A, VEGF-E did not bind to VEGF receptor-1 (Flt-1). VEGF-E is thus a potent angiogenic factor selectively binding to VEGF receptor-2. These data strongly indicate that activation of VEGF receptor-2 alone can efficiently stimulate angiogenesis.

540 citations


Journal ArticleDOI
TL;DR: In this article, a three-dimensional diagnostic diagram for Seyfert 2 galaxies obtained using X-ray and [O III] data on a large sample of objects was presented.
Abstract: We present and discuss a three-dimensional diagnostic diagram for Seyfert 2 galaxies obtained using X-ray and [O III] data on a large sample of objects (reported in the Appendix). The diagram shows the Kα iron line equivalent width as a function of both the column density derived from the photoelectric cutoff and the 2-10 keV flux normalized to the [O III] optical-line flux (the latter corrected for extinction and assumed to be a true indicator of the source intrinsic luminosity). We find that the hard X-ray properties of type 2 objects depend on a single parameter, the absorbing column density along the line of sight, in accordance with the unified model. The diagram can be used to identify Compton-thick sources and to isolate and study peculiar objects. From this analysis we have obtained a column density distribution of Seyfert 2 galaxies that is thought to be a good approximation of the real distribution. A large population of heavily absorbed objects is discovered, including many Compton-thick candidates. Our results indicate that the mean log NH cm-2 in type 2 Seyfert galaxies is 23.5 and that as many as 23%-30% of sources have NH ≥ 1024 cm-2.

495 citations


Journal ArticleDOI
TL;DR: The Th1/Th2 paradigm provides the rationale for the development of new types of vaccines against infectious agents and of novel strategies for the therapy of allergic and autoimmune disorders and may play some role in a more rapid evolution of human immunodeficiency virus infection to the full-blown disease.
Abstract: A large body of evidence indicates the existence of functionally polarized CD4+ T-cell responses based on their profile of cytokine secretion. Type 1 T helper (Th1) cells produce interferon-gamma, interleukin (IL)-2, and tumour necrosis factor (TNF)-beta, which activate macrophages and are responsible for cell-mediated immunity and phagocyte-dependent protective responses. By contrast, type 2 Th (Th2) cells produce IL-4, IL-5, IL-10, and IL-13, which are responsible for strong antibody production, eosinophil activation, and inhibition of several macrophage functions, thus providing phagocyte-independent protective responses. Th1 cells mainly develop following infections by intracellular bacteria and some viruses, whereas Th2 cells predominate in response to infestations by gastrointestinal nematodes. Polarized Th1 and Th2 cells not only exhibit different functional properties, but also show the preferential expression of some activation markers and distinct transcription factors. Several mechanisms may influence the Th cell differentiation, which include the cytokine profile of "natural immunity" evoked by different offending agents, the nature of the peptide ligand, as well as the activity of some costimulatory molecules and microenvironmentally secreted hormones, in the context of the individual genetic background. In addition to playing different roles in protection, polarized Th1-type and Th2-type responses are also responsible for different types of immunopathological reactions. Th1 cells are involved in the pathogenesis of organ-specific autoimmune disorders, Crohn's disease, Helicobacter pylori-induced peptic ulcer, acute kidney allograft rejection, and unexplained recurrent abortions. In contrast, allergen-specific Th2 responses are responsible for atopic disorders in genetically susceptible individuals. Moreover, Th2 responses against still unknown antigens predominate in Omenn's syndrome, idiopathic pulmonary fibrosis, and progressive systemic sclerosis. Finally, the prevalence of Th2 responses may play some role in a more rapid evolution of human immunodeficiency virus infection to the full-blown disease. The Th1/Th2 paradigm also provides the rationale for the development of new types of vaccines against infectious agents and of novel strategies for the therapy of allergic and autoimmune disorders.

411 citations


Journal ArticleDOI
TL;DR: In this article, the synthesis, crystal structure, and magnetic characterization of a novel tetranuclear iron(III) methoxo-bridged cluster of formula Fe4(OCH3)6(dpm)6 (where Hdpm = dipivaloylmethane) is reported.
Abstract: The synthesis, crystal structure, and magnetic characterization of a novel tetranuclear iron(III) methoxo-bridged cluster of formula Fe4(OCH3)6(dpm)6 (where Hdpm = dipivaloylmethane) is reported. The cluster has a ground spin state of S = 5, which is selectively populated below 20 K. High-field EPR spectra revealed that the system has a uniaxial magnetic anisotropy, corresponding to a zero field splitting parameter D = −0.2 cm-1 of the S = 5. Such anisotropy below 1 K gives rise to the slow relaxation of the magnetization similar to that of super-paramagnets. To investigate the origin of the magnetic anisotropy we have evaluated the projection of the single-ion and dipolar contributions to the zfs of the ground state. The zfs tensors of the three structurally independent iron(III) centers have been calculated from the coordination geometry and spectroscopic data using the angular overlap model. To test the reliability of the approach high-field EPR spectra of the parent monomer Fe(dpm)3 have been recorded...

400 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that a finite-dimensional continuous-time system is forward complete if solutions exist globally, for positive time, in a necessary and sufficient manner by means of smooth scalar growth inequalities.

389 citations


Journal ArticleDOI
TL;DR: In this article, the stability and stabilizability properties of systems with discontinuous righthand side (with solutions intended in Filippov's sense) by means of locally Lipschitz continuous and regular Lyapunov functions were studied.
Abstract: We study stability and stabilizability properties of systems with discontinuous righthand side (with solutions intended in Filippov's sense) by means of locally Lipschitz continuous and regular Lyapunov functions. The stability result is obtained in the more general context of differential inclusions. Concerning stabilizability, we focus on systems affine with respect to the input: we give some sufficient conditions for a system to be stabilized by means of a feedback law of the Jurdjevic-Quinn type.

Journal ArticleDOI
TL;DR: A number of metabolites affecting brain function originate from tryptophan metabolism and selective inhibitors of their forming enzymes may be useful to understand their role in physiology or as therapeutic agents in pathology.

Journal ArticleDOI
TL;DR: It is found that grape berries that are damaged are very rich depositories of microorganisms including S. cerevisiae, and that one in four such berries is S. Cerevisiae-positive, and it is believed that the yeasts are brought to the berries by insects such as bees, wasps, and Drosophila and that they multiply in the rich medium of the grape interior.

Journal ArticleDOI
TL;DR: In this article, the authors present a self-consistent empirical model for several plasma parameters in the extended solar corona above a polar coronal hole, derived from observations with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) during the period between 1996 November and 1997 April.
Abstract: We present a comprehensive and self-consistent empirical model for several plasma parameters in the extended solar corona above a polar coronal hole. The model is derived from observations with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) during the period between 1996 November and 1997 April. We compare observations of H I Lyα and O VI λλ1032, 1037 emission lines with detailed three-dimensional models of the plasma parameters and iterate for optimal consistency between measured and synthesized observable quantities. Empirical constraints are obtained for the radial and latitudinal distribution of density for electrons, H0, and O5+, as well as the outflow velocity and unresolved anisotropic most probable speeds for H0 and O5+. The electron density measured by UVCS/SOHO is consistent with previous solar minimum determinations of the white-light coronal structure; we also perform a statistical analysis of the distribution of polar plumes using a long time series. From the emission lines we find that the unexpectedly large line widths of H0 atoms and O5+ ions at most heights are the result of anisotropic velocity distributions. These distributions are not consistent with purely thermal motions or the expected motions from a combination of thermal and transverse wave velocities. Above 2 R☉, the observed transverse most probable speeds for O5+ are significantly larger than the corresponding motions for H0, and the outflow velocities of O5+ are also significantly larger than the corresponding velocities of H0. Also, the latitudinal dependence of intensity constrains the geometry of the wind velocity vectors, and superradial expansion is more consistent with observations than radial flow. We discuss the constraints and implications on various theoretical models of coronal heating and acceleration.

Journal ArticleDOI
TL;DR: The results of this study indicate that there is a direct relation between flap thickness and recession reduction (P <0.0001), and flap thickness >0.8 mm was associated with 100% of root coverage.
Abstract: This clinical study was designed to determine whether the thickness of the flap can influence root coverage when gingival recessions associated with traumatic toothbrushing are treated using a coronally advanced flap (CAF). Nineteen patients, aged from 25 to 57 years, with high levels of oral hygiene (full-mouth plaque scores or =2 mm were treated. After local anesthesia and before flap elevation, the exposed root surface was planed with a sharp curet. A trapezoidal full- and partial-thickness flap was then elevated, displaced coronally, and sutured to cover the treated root surface. Before suturing, flap thickness was measured in the alveolar mucosa with a gauge. After surgery, all patients were recalled for control and professional prophylaxis once a week during the first month and monthly up to the third month. The mean initial recession depth was 3.0+/-0.9 mm. Mean flap thickness (FT) was 0.7+/-0.2 mm. Three months later, mean recession depth was 0.6+/-0.6 (P 0.8 mm was associated with 100% of root coverage. The results of this study indicate that there is a direct relation between flap thickness and recession reduction (P <0.0001).

Journal ArticleDOI
TL;DR: In this paper, the authors contribute to the current debate on welfare regimes, bringing together the widespread need for a fourth welfare regime besides Esping-Andersen's well-known typology, and the results of a recent study.
Abstract: The article contributes to the current debate on welfare regimes, bringing together the widespread need for a fourth welfare regime besides Esping-Andersen's well-known typol ogy, and the results o...

Journal ArticleDOI
TL;DR: In this paper, the chemical evolution of the Galaxy for elements from Ba to Eu, using an evolutionary model suitable for reproducing a large set of Galactic (local and nonlocal) and extragalactic constraints, has been studied.
Abstract: We follow the chemical evolution of the Galaxy for elements from Ba to Eu, using an evolutionary model suitable for reproducing a large set of Galactic (local and nonlocal) and extragalactic constraints. Input stellar yields for neutron-rich nuclei have been separated into their s-process and r-process components. The production of s-process elements in thermally pulsing asymptotic giant branch stars of low mass proceeds from the combined operation of two neutron sources: the dominant reaction 13C(α, n)16O, which releases neutrons in radiative conditions during the interpulse phase, and the reaction 22Ne(α, n)25Mg, marginally activated during thermal instabilities. The resulting s-process distribution is strongly dependent on the stellar metallicity. For the standard model discussed in this paper, there is a sharp production of the Ba-peak elements around Z Z☉/4. Concerning the r-process yields, we assume that the production of r-nuclei is a primary process occurring in stars near the lowest mass limit for Type II supernova progenitors. The r-contribution to each nucleus is computed as the difference between its solar abundance and its s-contribution, given by the Galactic chemical evolution model at the epoch of the formation of the solar system. We compare our results with spectroscopic abundances of elements from Ba to Eu at various metallicities (mainly from F and G stars), showing that the observed trends can be understood in the light of present knowledge of neutron capture nucleosynthesis. Finally, we discuss a number of emerging features that deserve further scrutiny.

Journal ArticleDOI
01 Aug 1999-Fuel
TL;DR: In this article, the upgrading of wood pyrolysis oils produced in the ENEL fast-pyrolytic plant located in Bastardo, Italy, and in the Union Fenosa fast-polymerous plants located in La Coruna, Spain was studied by using HZSM-5 and H-Y zeolites in a fixed-bed laboratory scale reactor, at different temperatures and residence times.

Journal ArticleDOI
TL;DR: Comparison of the rates of folding of AcP and four other proteins with the same topology, including ADA2h, supports the concept that the average distance in sequence between interacting residues (that is, the contact order) is an important determinant of the rate of protein folding.
Abstract: Muscle acylphosphatase (AcP) is a small protein that folds very slowly with two-state behavior. The conformational stability and the rates of folding and unfolding have been determined for a number of mutants of AcP in order to characterize the structure of the folding transition state. The results show that the transition state is an expanded version of the native protein, where most of the native interactions are partially established. The transition state of AcP turns out to be remarkably similar in structure to that of the activation domain of procarboxypeptidase A2 (ADA2h), a protein having the same overall topology but sharing only 13% sequence identity with AcP. This suggests that transition states are conserved between proteins with the same native fold. Comparison of the rates of folding of AcP and four other proteins with the same topology, including ADA2h, supports the concept that the average distance in sequence between interacting residues (that is, the contact order) is an important determinant of the rate of protein folding.

Journal ArticleDOI
TL;DR: Elastography has the potential to become a reliable and accurate modality for HIFU therapy monitoring and a high correlation between the damaged areas as depicted by the elastograms and the corresponding areas as measured from the gross pathology photographs was found.
Abstract: The elastographic visualization and evaluation of high-intensity focused ultrasound (HIFU)-induced lesions were investigated. The lesions were induced in vitro in freshly excised canine livers. The use of different treatment intensity levels and exposure times resulted in lesions of different sizes. Each lesion was clearly depicted by the corresponding elastogram as being an area harder than the background. The strain contrast of the lesion/background was found to be dependent on the level of energy deposition. A lesion/background strain contrast between 22.5 dB and 23.5 dB was found to completely define the entire zone of tissue damage. The area of tissue damage was automatically estimated from the elastograms by evaluating the number of pixels enclosed inside the isointensity contour lines corresponding to a strain contrast of 22.5, 23 and 23.5 dB. The area of the lesion was measured from a tissue photograph obtained at approximately the same plane where elastographic data were collected. The estimated lesion areas ranged between approximately 10 mm 2 and 110 mm 2 . A high correlation between the damaged areas as depicted by the elastograms and the corresponding areas as measured from the gross pathology photographs was found (r 2 5 0.93, p value < 0.0004, n 5 16). This statistically significant high correlation demonstrates that elastography has the potential to become a reliable and accurate modality for HIFU therapy monitoring. © 1999 World Federation for Ultrasound in Medicine & Biology.

Journal ArticleDOI
TL;DR: In this paper, a review of different experimental situations is presented, including a discussion on suitable indicators which characterize the different regimes, and a view on perspective new phenomena and applications include an extension to atom optics.

Journal ArticleDOI
TL;DR: The data confirm the validity of EPDS in identifying postnatal depression also in its Italian version and the scale could be used as an useful instrument in the clinical practice.

Journal ArticleDOI
TL;DR: A compositional approach increases the level of representation that can be automatically extracted and used in a visual information retrieval system.
Abstract: A compositional approach increases the level of representation that can be automatically extracted and used in a visual information retrieval system. Visual information at the perceptual level is aggregated according to a set of rules. These rules reflect the specific context and transform perceptual words into phrases capturing pictorial content at a higher, and closer to the human, semantic level.

Journal ArticleDOI
TL;DR: A potential direct profibrogenic action of MCP‐1 is shown via HSC chemotaxis for the first time, and this study shows that the increase in cell migration was almost completely a result ofChemotaxis rather than chemokinesis.

Journal ArticleDOI
TL;DR: In this paper, an improved small-x$ equation with exact leading and next-to-leading Balitski-Kuraev-Lipatov kernels and renormalization group constraints was proposed and analyzed.
Abstract: We propose and analyze an improved small-$x$ equation which incorporates exact leading and next-to-leading Balitski\ifmmode \breve{\imath}\else \u{\i}\fi{}-Fadin-Kuraev-Lipatov kernels on one hand and renormalization group constraints in the relevant collinear limits on the other. We work out in detail the recently proposed $\ensuremath{\omega}$ expansion of the solution, derive the Green's function factorization properties and discuss both the gluon anomalous dimension and the hard Pomeron. The resummed results are stable, nearly renormalization-scheme independent, and join smoothly with the fixed order perturbative regime. Two critical hard Pomeron exponents ${\ensuremath{\omega}}_{c}{(Q}^{2})$ and ${\ensuremath{\omega}}_{s}{(Q}^{2})$ are provided, which --- for reasonable strong-coupling extrapolations --- are argued to provide bounds on the Pomeron intercept ${\ensuremath{\omega}}_{P}.$

Journal ArticleDOI
TL;DR: This study has demonstrated the feasibility of outdoor cultivation of Nannochloropsis sp.

Journal ArticleDOI
TL;DR: The results indicate that OMWW extracts are able to inhibit human LDL oxidation and to scavenge superoxide anions and hypochlorous acid at concentrations as low as 20 ppm.
Abstract: During olive oil production, large volumes of water are generated and subsequently discarded. Olives contain a variety of bioactive components, and some of them, according to their partition coefficients, end up in the water phase. The current investigation aimed at comparing different methods for the extraction of biologically active components of the olive mill waste waters (OMWW) and evaluating the in vitro antioxidant and anti-inflammatory activities of the resulting extracts. The results indicate that OMWW extracts are able to inhibit human LDL oxidation (a process involved in the pathogenesis of atherosclerosis) and to scavenge superoxide anions and hypochlorous acid at concentrations as low as 20 ppm. Finally, two of the three extracts also inhibited the production of leukotrienes by human neutrophils. The potency of the extracts depended on their degree of refinement: extracts containing only low molecular weight phenols were the most effective.

Journal ArticleDOI
TL;DR: The effectiveness of the treatment using calcinogenic bacteria has been evaluated with laboratory tests specifically developed to evaluate the parameters such as porosity, superficial strength and chromatic changes, influenced by the treatment itself, to indicate that this type of treatment might not be suitable for monumental stone conservation.

Journal ArticleDOI
TL;DR: Compared with indomethacin, ibuprofen did not significantly reduce mesenteric and renal blood flow velocity, and blood flow increased 120 minutes after treatment.

Journal ArticleDOI
TL;DR: Magnetostratigraphic and biostrigraphic results from Neogene deposits in the Taza-Guercif Basin, located at the southern margin of the Rifian Corridor in Morocco, were presented in this paper.