1,125 research outputs found
Time-dependent local Green's operator and its applications to manganites
An algorithm is presented to calculate the electronic local time-dependent
Green's operator for manganites-related hamiltonians. This algorithm is proved
to scale with the number of states in the Hilbert-space to the 1.55 power,
is able of parallel implementation, and outperforms computationally the Exact
Diagonalization (ED) method for clusters larger than 64 sites (using
parallelization). This method together with the Monte Carlo (MC) technique is
used to derive new results for the manganites phase diagram for the spatial
dimension D=3 and half-filling on a 12x12x12 cluster (3456 orbitals). We obtain
as a function of an insulating parameter, the sequence of ground states given
by: ferromagnetic (FM), antiferromagnetic AF-type A, AF-type CE, dimer and
AF-type G, which are in remarkable agreement with experimental results.Comment: 9 pages, 11 figure
Effect of Sr substitution on superconductivity in Hg2(Ba1-ySry)2YCu2O8-d (part2): bond valence sum approach of the hole distribution
The effects of Sr substitution on superconductivity, and more particulary the
changes induced in the hole doping mechanism, were investigated in
Hg2(Ba1-ySry)2YCu2O8-d by a "bond valence sum" analysis with Sr content from y
= 0.0 to y = 1.0. A comparison with CuBa2YCu2O7-d and Cu2Ba2YCu2O8 systems
suggests a possible explanation of the Tc enhancement from 0 K for y = 0.0 to
42 K for y = 1.0. The charge distribution among atoms of the unit cell was
determined from the refined structure, for y = 0.0 to 1.0. It shows a charge
transfer to the superconducting CuO2 plane via two doping channels pi(1) and
pi(2), i.e. through O2(apical)-Cu and Ba/Sr-O1 bonds respectively.Comment: 13 pages, 5 figures, accepted for publication in Journal of Physics:
Condensed Matte
A method for the location of noise-polluted area
This paper deals with the working out of a method suitable to locate the critical areas from an acoustic point of view inside the pertinence zones of the roads. We have applied our method to about one thousand kilometres of major roads managed by ANAS in Lombardia. The procedure is based on the coupling of a Geographic Information System (GIS) with an acoustics simulation model. In order to characterize the noise sources in the prediction software, it has been necessary to estimate in every significant section of the streets the day and night average fluxes of vehicles, the vehicle typology and their average velocity. This study started from a statistical analysis of the experimental data obtained by sound measurements and by counting the vehicle fluxes. As a result, we have obtained on a GIS the acoustics map of the whole Lombardia road network with information on where the noise limits classes are exceeded
Errors evaluation in the estimate of the noise from the road traffic
Specific algorithms together with noise data acquired during a measurement campaign, consisting of approximately 80 one-hour records, were utilized to model the noise levels of a road network. Experimental measurements were used to evaluate the reliability of the model by analyzing the differences between the measured values and the estimated ones. We think that these differences have to
be especially ascribed to an imperfect representation of the combined effects of the attenuation due to acoustic wave diffraction and the attenuation produced by the
ground effect
Ferromagnetic Polarons in La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3
Unrestricted Hartree-Fock calculations on La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3
in the full magnetic unit cell show that the magnetic ground states of these
compounds consist of 'ferromagnetic molecules' or polarons ordered in
herring-bone patterns. Each polaron consists of either three or five Mn ions
separated by O- ions with a magnetic moment opposed to those of the Mn ions.
Ferromagnetic coupling within the polarons is strong while coupling between
them is relatively weak. Magnetic moments on the Mn ions range between 3.8 and
3.9 Bohr magnetons in La0.5Ca0.5MnO3 and moments on the O- ions are -0.7 Bohr
magnetons. Each polaron has a net magnetic moment of 7.0 Bohr magnetons, in
good agreement with recently reported magnetisation measurements from electron
microscopy. The polaronic nature of the electronic structure reported here is
obviously related to the Zener polaron model recently proposed for
Pr0.6Ca0.4MnO3 on the basis of neutron scattering data.Comment: 4 pages 5 figure
Immunohistochemical localization of constitutive and inducible heat shock protein 70 in carp (Cyprinus carpio) and trout (Oncorhynchus mykiss) exposed to transport stress.
In the present work we investigated by immunohistochemistry the cellular localization of constitutive as well as inducible heat shock protein 70 in several tissues of common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) exposed to transport stress. In carp, the constitutive form (HSC70) was detected only in red skeletal muscle of both control and stressed animals. In the same species, the inducible form (HSP70) was evident in the epithelia of renal tubules, gills and skin of stressed animals, whereas in controls only red skeletal muscle exhibited an immunopositivity to HSP70 antibody. In trout, immunostaining to HSC70 antibody was found mainly in the epithelia of intestine, gills and skin of both control and stressed animals although the reactivity was generally higher in animals exposed to transport stress. In the same species immunostaining to HSP70 antibody was observed only in red skeletal muscle and epidermis of control animals
Characteristics of Invasive Pneumococcal Disease in Young Children before the Introduction of PCV13 in Lombardy, Italy
An active surveillance system of invasive pneumococcal disease (IPD) started on September 2008 in Lombardy, Italy, among children aged less than 60 months and admitted for suspicion of IPD at emergency room of ten hospitals. This study examined the clinical characteristics of children enrolled up to December 2010, that is just before the introduction in this region of voluntary mass vaccination, free of charge, based on the 13-valent pneumococcal conjugate vaccine (PCV13). Two hundred fifty one children were suspected and 20 were confirmed as having IPD, based on isolation of Streptococcus pneumoniae from blood. Thirty-nine percent of children had received pneumococcal vaccination previously, and full vaccination with three doses of hepta-valent vaccine (PCV7) had been administered in 21.4%. Co-morbidity conditions were more frequent in children with confirmed than non-confirmed IPD (10.0% vs. 0.9%). The annual incidence rate of confirmed IPD was 28.6/100,000 (binomial 95% confidence interval, 18.6 to 44.1/100,000. Among confirmed IPD children, 11 exhibited pneumonia with bacteremia, 6 bacteremia without focus, 2 septicemia, 1 meningitis. Seventeen (85%) isolates were identified, and nine serotypes. The overall serotype coverage was 29.4% for PCV7 and 82.3% for PCV13. In non-vaccinated children, the coverage of PCV7 and PCV13 was 41.7% and 75.0%, respectively. Non-vaccine serotypes 12B, 15C, and 23B were identified. Antibiotic resistance was found in seven children, that is against penicillin (serotype 15C), erythromycin (14, 19A, 19F), tetracycline (15C, 19F), chloramphenicol (23F), and trimethoprim-sulfamethoxazole (23F). Two of these children had received antibiotic therapy (penicillin or azithromycin) during the week before hospital admission. The coverage vaccination rate in Lombardy was relatively low during the surveillance period and serotype distribution widespread. The introduction of PCV13 and a mass vaccination program in young children might impact positively on invasive pneumococcal disease in this surveilled population. Active long-term surveillance of non-vaccine serotypes is required wordwide
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