Polaronic signature in the metallic phase of La0.7Ca0.3MnO3 films detected by scanning tunneling spectroscopy

In this work we map tunnel conductance curves with nanometric spatial resolution, tracking polaronic quasiparticle excitations when cooling across the insulator-to-metal transition in La0.7Ca0.3MnO3 films. In the insulating phase the spectral signature of polarons, a depletion of conductance at low bias flanked by peaks, is detected all over the scanned surface. These features are still observed at the transition and persist on cooling into the metallic phase. Polaron-binding energy maps reveal that polarons are not confined to regions embedded in a highly-conducting matrix but are present over the whole field of view both above and below the transition temperature.Comment: 10 pages, 4 figure

Strong-coupling analysis of scanning tunneling spectra in Bi2_2Sr2_2Ca2_2Cu3_3O10+δ_{10+\delta}

We study a series of spectra measured in the superconducting state of optimally-doped Bi-2223 by scanning tunneling spectroscopy. Each spectrum, as well as the average of spectra presenting the same gap, is fitted using a strong-coupling model taking into account the band structure, the BCS gap, and the interaction of electrons with the spin resonance. After describing our measurements and the main characteristics of the strong-coupling model, we report the whole set of parameters determined from the fits, and we discuss trends as a function of the gap magnitude. We also simulate angle-resolved photoemission spectra, and compare with recent experimental results.Comment: Published versio

Kawasaki disease in Sicily: clinical description and markers of disease severity

Background: Kawasaki disease (KD) is an acute systemic vasculitis of small and middle size arteries; 15-25 % of untreated patients and 5 % of patients treated with intravenous immunoglobulin (IVIG) develop coronary artery lesions (CAL). Many studies tried to find the most effective treatment in the management of resistant KD and to select the risk factors for CAL. Our data are assessed on children from west Sicily, characterized by a genetic heterogeneity. Methods: We studied the clinical data of 70 KD Sicilian children (36 males: 51 %; 34 females: 49 %), analysed retrospectively, including: demographic and laboratory parameters; echocardiographic findings at diagnosis, at 2, 6 and 8 weeks, and at 1 year after the onset of the illness. Results: Forty-seven had Typical KD, three Atypical KD and twenty Incomplete KD. Age at the disease onset ranged from 0.1 to 8.9 years. IVIG were administered 5 \ub1 2 days after the fever started. Defervescence occurred 39 \ub1 26 hours after the first IVIG infusion. Fifty-six patients (80 %) received 1 dose of IVIG (responders); 14 patients (20 %) had a resistant KD, with persistent fever after the first IVIG dose (non responders). Ten (14 %) non responders responded to the second dose, 4 (5 %) responded to three doses; one needed treatment with high doses of steroids and Infliximab. Cardiac involvement was documented in twenty-two cases (eighteen with transient dilatation/ectasia, fifteen with aneurysms). Pericardial effusion, documented in eleven, was associated with coronaritis and aneurysms, and was present earlier than coronary involvement in seven. Hypoalbuminemia, D-dimer pre-IVIG, gamma-GT pre-IVIG showed a statistically significant direct correlation with IVIG doses, highlighting the role of these parameters as predictor markers of refractory disease. The persistence of elevated CRP, AST, ALT levels, a persistent hyponatremia and hypoalbuminemia after IVIG therapy, also had a statistical significant correlation with IVIG doses. Non responders showed higher levels of D-dimer and gamma-GT pre-IVIG, persistent high levels of D-dimer, CRP, AST, ALT, hypoalbuminemia and hyponatremia after IVIG. Conclusions: This is the first study on KD in Sicily. We suggest some laboratory parameters as predictive criteria for resistant KD. Patients who show early pericarditis need careful surveillance for coronary lesions

Devolatilization of organo-sulfur compounds in coal gasification

Coal gasification is a thermo-chemical process aiming at the production of high heating value syngas. The coal charges present, typically, a low quantity of sulfur compounds for prevent the formation of a large amount of sulfuric acid (H2S), that is a pollutant and a poison for catalysts, in syngas stream. However, in the world there are a lot of coals that cannot be used for gasification because of their high sulfur content (e.g. Sulcis Italian coal or Inner Mongolia Chinese coal). The interest on these types of coal is increasing due to a novel technology that allows to convert H2S and CO2into syngas (AG2S\u2122). The aim of this work is to propose a predictive kinetic model of the release of sulfur compounds (e.g H2S) from coal. This kinetic scheme is implement into GASDS, a package that includes a gasifier mathematical model, which accurately describes the inter-phase mass and heat transfer. The first complexity relies in the characterization of the coal, in particular the relative amount of the different forms of sulfur components (e.g. inorganic such as pyritic and sulfates, and organic sulfur such as aliphatic, aromatic and thiophenic) and their pyrolysis and devolatilization process. The kinetic model, with the related rate parameters, is validated through comparison with experimental data from the literature and obtained during several experimental campaigns at the Sotacarbo S.p.A. pilot platform. Finally, different operating conditions of gasification are analyzed in order to obtain the best yield in the downstream process, with special reference to the novel Acid Gas to Syngas (AG2STM) process

Fingerprint of dynamical charge/spin correlations in the tunneling spectra of colossal magnetoresistive manganites

We present temperature-dependent scanning tunneling spectroscopy measurements on $La_{1-x}Ca_{x}MO_{3}$ ($x\sim0.33$) films with different degrees of biaxial strain. A depletion in normalized conductance around the Fermi level is observed both above and below the insulator-to-metal transition temperature $T_{MI}$, for weakly as well as highly-strained films. This pseudogap-like depletion globally narrows on cooling. The zero-bias conductance decreases on cooling in the insulating phase, reaches a minimum close to $T_{MI}$ and increases on cooling in the metallic phase, following the trend of macroscopic conductivity. These results support a recently proposed scenario in which dynamical short-range antiferromagnetic/charge order correlations play a preeminent role in the transport properties of colossal magnetoresistive manganites [R. Yu \textit{et al}., Phys. Rev. B \textbf{77}, 214434 (2008)].Comment: 9 pages, 4 figure

Systemic lupus erythematosus and bullous pemphigoid with dramatic response to dapsone

Objective: Unusual clinical course Background: Bullous pemphigoid is an autoimmune blistering disease, with relapses, isolated or associated with other autoimmune diseases such as systemic lupus erythematosus (SLE). Joint manifestations rapidly respond to small or moderate doses of corticosteroids, whereas skin manifestations usually respond to antimalarial drugs. Case Report: We describe the clinical case of an 11-year-old girl with SLE. She showed bullous skin lesions with arthralgia, mild proteinuria, resolved after steroid treatment. At the tapering of her prednisone dose, the patient had new skin lesions requiring an increased dose of prednisone. She started dapsone at the dosage of 1 mg/kg/day, maintaining low dose prednisone; this treatment was successfully followed by the dramatic disappearance of skin lesions and limb pain. Conclusions: Bullous skin lesions can represent the first clinical presentation of pediatric SLE and could influence the treatment and the outcome of these patients. This case showed an atypical course as both skin manifestations and arthritis promptly and persistently resolved with dapsone without the use of high-dose glucocorticoids. Only a few cases of patients with SLE associated with bullous pemphigoid have been reported in the literature, and very few in the pediatric population

Do not disturb the family: roles of colony size and human disturbance in the genetic structure of lesser kestrel

Dispersal and philopatry are fundamental processes influencing the genetic structure and persistence of populations and might be affected by isolation and habitat perturbation. Habitat degradation induced by human activities could have detrimental consequences on genetic structure of populations. Therefore, it is crucial to understand the role of human impacts in promoting or disrupting genetic structure. Here, we conducted a genetic analysis using 12 polymorphic microsatellite markers of 70 lesser kestrels (Falco naumanni) from 10 breeding colonies of two subpopulations in Sicily (southern Italy). Genetic differentiation between the two subpopulations was negligible, and linear distances played no role in the level of genetic relatedness recorded in the two sites. Linear distances between nests also resulted in no effects on the relatedness recorded within and between colonies in the largest subpopulation. Clusters of more versus less related individuals resulted when the two-dimensional positions of colonies (i.e., latitude and longitude) were tested as predictors of genetic proximity instead of linear distances. Specifically, analyses of colony features showed colony size and human disturbance as factors negatively affecting the relatedness among chicks from different nests. Regardless of colony size, less-related individuals were born in colonies located in the core of the agricultural plain, where we quantified a higher level of human disturbance. In contrast, more related individuals were in colonies that existed in the marginal, less disturbed, agricultural area. Given the high philopatry of this species, our results are consistent with disruption of colony fidelity related to intensification of agricultural practices. We discuss the possible implications of long-term effects of genetic variability in small and disturbed colonies on fitness and population viability

Coronal Abundances in Orion Nebula Cluster Stars

Following the Chandra Orion Ultradeep Project (COUP) observation, we have studied the chemical composition of the hot plasma in a sample of 146 X-ray bright pre-main sequence stars in the Orion Nebula Cluster. We report measurements of individual element abundances for a subsample of 86 slightly-absorbed and bright X-ray sources, using low resolution X-ray spectra obtained from the Chandra ACIS instrument. The X-ray emission originates from a plasma with temperatures and elemental abundances very similar to those of active coronae in older stars. A clear pattern of abundances vs. First Ionization Potential (FIP) is evident if solar photospheric abundances are assumed as reference. The results are validated by extensive simulations. The observed abundance distributions are compatible with a single pattern of abundances for all stars, although a weak dependence on flare loop size may be present. The abundance of calcium is the only one which appears to vary substantially between stars, but this quantity is affected by relatively large uncertainties. The ensemble properties of the X-ray bright COUP sources confirm that the iron in the emitting plasma is underabundant with respect to both the solar composition and to the average stellar photospheric values. Comparison of the present plasma abundances with those of the stellar photospheres and those of the gaseous component of the nebula, indicates a good agreement for all the other elements with available measurements, and in particular for the high-FIP elements (Ne, Ar, O, and S) and for the low-FIP element Si. We conclude that there is evidence of a significant chemical fractionation effect only for iron, which appears to be depleted by a factor 1.5--3 with respect to the stellar composition

POTENZIALI EVOCATI VISIVI DA FLASH IN GEMELLI IN EPOCA NEONATALE. CORRELAZIONI CON LA ADEGUATEZZA DEL PESO CON LA ETA' GESTAZIONALE (AGA VS SGA)

Neonati AGA, SGA, PE