246 research outputs found

    Oxygen-isotope effect on the in-plane penetration depth in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} as revealed by muon-spin rotation

    Full text link
    The oxygen-isotope (^16O/^18O) effect (OIE) on the in-plane penetration depth λab(0)\lambda_{ab} (0) in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} was studied by muon-spin rotation. A pronounced OIE on λab−2(0)\lambda_{ab}^{-2}(0) was observed with a relative isotope shift of Δλab−2/λab−2\Delta\lambda^{-2}_{ab}/\lambda^{-2}_{ab}=-5(2)% for x =0.3 and -9(2)% for x=0.4. It arises mainly from the oxygen-mass dependence of the in-plane effective mass mab∗m_{ab}^{\ast}. The OIE exponents of T_{c} and of λab−2(0)\lambda_{ab}^{-2}(0) exhibit a relation that appears to be generic for cuprate superconductors.Comment: 4 pages, 4 eps figures, RevTex

    Lantana camara (verbenaceae) : a potential threat to the effectiveness of protected areas to conserve flora and fauna in Benin

    Get PDF
    Invasive plant species are today among the biggest threats to integrity of many ecosystems including that of the protected areas. Climate change may exacerbate the negative effects of invasive plant species. Here, we used the Maximum Entropy model to project habitat suitability for Lantana camara L., an invasive plant species under current and future climates in the national protected areas network of Benin. The models were run using bioclimatic data and data on soil type. Nineteen percent of the total land in the protected areas network was highly suitable for L. camara under current climate. Highly suitable areas under current and future climates cover about 65 % of the Pendjari Biosphere Reserve, the major wildlife sanctuary in Benin. Other bio-reserves such as W National Park, Lama, Agoua, Dogo-Kétou, Atchérigbé, Mékrou and Kouandé Forest Reserves were also suitable for the species. Presence of L. camara in the protected areas represents a great potential threat to the global food webs being conserved. Based on these results, areas with highly suitable habitats are at high risk of invasion by L. camara, and should be accorded high priority when formulating appropriate management strategies.Keywords: Invasive species ; Climate change ; Habitat suitability ; Protected areas ; West AfricaLantana camara et les aires protegees au BeninLes espèces invasives font de nos jours partie des plus importantes menaces aux quelles font face les écosystèmes y compris les aires protégées. Les changements climatiques peuvent amplifier leurs effets négatifs. Dans la présente étude, nous avons utilisé un algorithme de modélisation de niche écologique, le Maximum Entropy pour analyser la susceptibilité des habitats à être colonisés par Lantana camara L., une plante invasive, sous les conditions climatiques actuelles et futures dans les aires protégées du Bénin. Les modèles ont été établis en utilisant des données bioclimatiques et des données relatives aux types de sol. Dans les conditions climatiques actuelles, 19 % de la superficie totale du réseau des aires protégées est significativement favorable à L. camara. Sous les conditions climatiques actuelles et futures, 65 % de la réserve de biosphère de Pendjari, le plus important sanctuaire de faune sauvage du Bénin, est hautement favorable à l’espèce. D’autres bio-réserves telles que le Parc National W et les reserves forestières de Lama, Agoua, Dogo-Kétou, Atchérigbé, Mékrou et Kouandé ont aussi des habitats favorable à l’espèce. En nous fondant sur ces résultats, les zones favorables sont à haut risque d’invasion par L. camara et  devraient être priorisées lors de la formulation de stratégies préventives appropriées.Mots clés: Espèces envahissantes ; Changements Climatiques ; Habitats favorables ; Aires protégées, Afrique de l’Ouest

    Association between migraine and HLA–DRB1 gene polymorphisms

    Get PDF
    We examined the distribution of HLA–DRB1 alleles in a cohort of 255 Italian migraine patients and in a control group of 325 healthy subjects. The frequency of DRB1*12 allele was found to be significantly reduced (p=0.02) in patients with migraine while the DRB1*16 allele was significantly increased (p=0.04) in comparison with controls. When the patients were divided into disease subgroups (migraine with and without aura), HLA–DRB1**16 allele was significantly increased (p<0.05) only in migraine without aura patients. We conclude that, in Italian patients, migraine is associated with different alleles of the HLA–DRB1 locus. Our data suggest the presence of a genetic susceptibility factor for migraine within the HLA region

    Acquisition Correction and Reconstruction for a Clinical SPECT/MRI Insert

    Get PDF
    The development of the first clinical simultaneous Single Photon Emission Computed Tomography (SPECT) and Magnetic Resonance Imaging (MRI) system was carried out within the INSERT project. The INSERT scanner was constructed under the initial project, but its performance was not fully evaluated; here we have reconstructed the first images on the SPECT system. Calibration and acquisition protocols were developed and used to establish the clinical feasibility of the system. The image reconstruction procedures were implemented on the first phantom images in order to assess the system's imaging capabilities. This study solved issues involving incomplete data sets and pixel failure in the prototype detector system. The final images determined a measure of trans-axial image resolution, giving average values of 9.14 mm and 6.75 mm in the radial and tangential directions respectively. The work carried out on the complete system produced several clinical phantom images which utilized the capabilities of both SPECT and MRI

    Oxygen-isotope effect on the in-plane penetration depth in cuprate superconductors

    Full text link
    Muon-spin rotation (muSR) studies of the oxygen isotope (^{16}O/^{18}O) effect (OIE) on the in-plane magnetic field penetration depth lambda_{ab} in cuprate high-temperature superconductors (HTS) are presented. First, the doping dependence of the OIE on the transition temperature T_c in various HTS is briefly discussed. It is observed that different cuprate families show a similar doping dependence of the OIE on T_c. Then, bulk muSR, low-energy muSR, and magnetization studies of the total and site-selective OIE on lambda_{ab} are described in some detail. A substantial OIE on lambda_{ab} was observed in various cuprate families at all doping levels, suggesting that cuprate HTS are non-adiabatic superconductors. The experiments clearly demonstrate that the total OIE on T_c and lambda_{ab} arise from the oxygen sites within the superconducting CuO_2 planes, demonstrating that the phonon modes involving the movement of planar oxygen are dominantly coupled to the supercarriers. Finally, it is shown that the OIE on T_c and lambda_{ab} exhibit a relation that appears to be generic for different families of cuprate HTS. The observation of these unusual isotope effects implies that lattice effects play an essential role in cuprate HTS and have to be considered in any realistic model of high-temperature superconductivity.Comment: 22 pages, 12 figures. To be published in a special issue of J. Phys. Cond. Ma

    Urticaria : recommendations from the Italian Society of Allergology, Asthma and Clinical Immunology and the Italian Society of Allergological, Occupational and Environmental Dermatology

    Get PDF
    Background: Urticaria is a disorder affecting skin and mucosal tissues characterized by the occurrence of wheals, angioedema or both, the latter defining the urticaria-angioedema syndrome. It is estimated that 12-22% of the general population has suffered at least one subtype of urticaria during life, but only a small percentage (estimated at 7.6-16%) has acute urticaria, because it is usually self-limited and resolves spontaneously without requiring medical attention. This makes likely that its incidence is underestimated. The epidemiological data currently available on chronic urticaria in many cases are deeply discordant and not univocal, but a recent Italian study, based on the consultation of a national registry, reports a prevalence of chronic spontaneous urticaria of 0.02% to 0.4% and an incidence of 0.1-1.5 cases/1000 inhabitants/year. Methods: We reviewed the recent international guidelines about urticaria and we described a methodologic approach based on classification, pathophysiology, impact on quality of life, diagnosis and prognosis, differential diagnosis and management of all the types of urticaria. Conclusions: The aim of the present document from the Italian Society of Allergology, Asthma and Clinical Immunology (SIAAIC) and the Italian Society of Allergological, Occupational and Environmental Dermatology (SIDAPA) is to provide updated information to all physicians involved in diagnosis and management of urticaria and angioedema

    Cerebellar astrocytes co-express several ADP receptors. Presence of functional P2Y13-like receptors

    Get PDF
    Astrocytes exhibit a form of excitability based on variations of intracellular Ca2+ concentration in response to various stimuli, including ADP, ATP, UTP and dinucleotides. Here, we investigate the presence of the recently cloned ADP-sensitive receptors, P2Y12 and P2Y13 subtypes, which are negatively coupled to adenylate cyclase, in cerebellar astrocytes. We checked the effect of specific agonists, 2-methylthioadenosine diphosphate (2MeSADP) and ADP, on adenylate cyclase stimulation induced by isoproterenol. Both agonists significantly reduced the cAMP accumulation induced by isoproterenol. The inhibitory effect was concentration-dependent with IC50 values of 46 ± 13 and 23 ± 14 nM for 2MeSADP and ADP, respectively. The experiments were carried out in the presence of MRS-2179, a specific antagonist of P2Y1 receptor, to avoid any contribution of this receptor. Using fura-2 microfluorimetry we also proved that astrocytes responded to 2MeSADP stimulations with calcium responses in the absence and also in the presence of MRS-2179. Both effects, inhibition of adenylate cyclase and intracellular calcium mobilization, were not modified by 2MeSAMP, an antagonist of P2Y12 receptor, suggesting that were mediated by P2Y13-like receptors

    Allergic sensitization to common pets (cats/dogs) according to different possible modalities of exposure: an Italian Multicenter Study

    Get PDF
    Background: The query "are there animals at home?" is usually administered for collecting information on anamnesis. This modality to consider exposure to pet allergens constitutes a potential bias in epidemiological studies and in clinical practice. The aim of our study was to evaluate/quantify different modalities of exposure to cat/dog in inducing allergic sensitization. Methods: Thirty Italian Allergy units participated in this study. Each centre was required to collect the data of at least 20 consecutive outpatients sensitized to cat/dog allergens. A standardized form reported all demographic data and a particular attention was paid in relieving possible modalities of exposure to cat/dog. Results: A total 723 patients sensitized to cat/dog were recorded, 359 (49.65%) reported direct pet contact, 213 patients (29.46%) were pet owners, and 146 subjects (20.19%) were exposed to pets in other settings. Other patients were sensitized by previous pet ownership (150-20.75%) or indirect contact (103-14.25%), in 111 subjects (15.35%) any contact was reported. Conclusions: Only 213 patients (29.46%) would be classified as "exposed to animals" and 510 (70.54%) as "not exposed" according to usual query. Our classification has shown that many "not-exposed" subjects (399-55.19%) were "really exposed". The magnitude of exposure to pet allergens at home is not related exclusively to pet ownership. These considerations should be taken into account during the planning of epidemiological studies and in clinical practice for the management of pet allergic individuals
    • …
    corecore