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Search Results: 1 - 10 of 714517 matches for " A. M. NICOLETTI "
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Comment on "Terahertz time-domain spectroscopy of transient metallic and superconducting states" (arXiv:1506.06758)
D. Nicoletti,M. Mitrano,A. Cantaluppi,A. Cavalleri
Physics , 2015,
Abstract: We comment on the model proposed by Orenstein and Dodge in arXiv:1506.06758v1, which describes time-domain terahertz measurements of transiently generated, high-electron-mobility (or superconducting) phases of solids. The authors' main conclusion is that time-domain terahertz spectroscopy does not measure a response function that is mathematically identical to the transient optical conductivity. We show that although this is correct, the difference between the measured response function and the microscopic optical conductivity is small for realistic experimental parameters. We also show that for the experiments reported by our group on light-induced superconducting-like phases in cuprates and in organic conductors, the time-domain terahertz yields a very good estimate for the optical conductivity.
Ceramic matrices applied to aerostatic porous journal bearings: material characterization and bearing modeling
Silveira, Z. C;Nicoletti, R;Fortulan, C. A;Purquerio, B. M;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000200016
Abstract: this paper presents the development of an advanced ceramic material for manufacturing aerostatic porous bearing. the results show that there is homogeneous distribution of the pores in the alumina matrix by using different concentrations of the added component (sucrose). the average pore diameter remained around 0.14 μm and respective porosity around 28%, with small standard deviation. the mathematical model of the aerostatic porous bearing is presented, and numerical results indicate that the parameter related to porous medium (г) strongly affects the resultant bearing load capacity and stiffness. considering the experimental and numerical results, the porous matrix obtained with 40% of sucrose concentration is more suitable for the aerostatic porous bearing application in study.
USO DE SUBPRODUTOS AGROINDUSTRIAIS NO DESENVOLVIMENTO DE MACARR O NUTRICIONALMENTE MELHORADO
A. M. NICOLETTI,L. P. SILVA,L. H. HECKTHEUER,G. S. P. TOLEDO
Alimentos e Nutri??o , 2008,
Abstract: O presente trabalho teve como objetivo desenvolver uma formula § £o de macarr £o nutricionalmente melhorado. Tal produto foi escolhido para o desenvolvimento deste estudo por ser um alimento popular, amplamente consumido e barato; por m, de caracter -stica prioritariamente energ tica, com defici ancias no teor e qualidade prot icas. Para corrigir estas defici ancias foram usados, como ingredientes majorit rios, a quirera de arroz e o farelo de soja, que s £o subprodutos agroindustriais de baixo custo e abundantemente produzidos no Pa -s. A formula § £o desenvolvida apresentou teor de prote -na 34,5% superior ao macarr £o convencional, bem como teor de fibra e minerais totais 2,6 e 1,9 vezes superiores, respectivamente, por m, sem alterar significativamente os valores energ ticos. Houve uma complementa § £o do padr £o aminoac -dico desta formula § £o, suprindo as recomenda § μes da FAO/WHO/ UNU tanto para crian §as como para adultos. Os resultados da an lise sensorial mostraram valores de aceitabilidade acima de 80% do macarr £o nutricionalmente melhorado, para ambos os p oblicos.
La Patagonia en los textos de geofrafía de la editorial "Obra de Don Bosco" de principios del siglo XX
Nicoletti,María Andrea;
Universum (Talca) , 2006, DOI: 10.4067/S0718-23762006000100005
Abstract: in this work we analyze the patagonia in the scholar books of geography belonging to the salesians (beginning of the xxth century). we observe this territorial construction as reflex and refraction of the social and political interests. about the treatment of these contents and the structuring we can see this region just in the difficult historical process of the incorporation to the nation. the congregation incorporates in these books, with official programs, information that denotes a special knowledge of the region in the different editions. these books reflect the national vision on the territories and describe the patagonia with images that show the civilization, the no-civilization, the unexplored land, the beauty and the wealth, against the unfertility and the dryness. the notes in the text bring us information about patagonia with productive potential and national future, capturing even the opinion of his inhabitants and the salesians.
La Patagonia en los textos de geofrafía de la editorial "Obra de Don Bosco" de principios del siglo XX
María Andrea Nicoletti
Universum : Revista de Humanidades y Ciencias Sociales , 2006,
Abstract: En este trabajo analizamos, a través de textos escolares de Geografía pertenecientes a la Congregación Salesiana de principios del siglo XX, los contenidos sobre la Patagonia. Nuestro objetivo es observar esta construcción territorial como reflejo y refracción del conjunto social y los intereses políticos. El tratamiento de estos contenidos y su jerarquización respecto de otros, es un modo de identificar y visualizar esta región -aun cuando no era considerada en los textos una región- en el discurso, en el marco del conflictivo proceso histórico de su incorporación a la Nación. La Congregación incorpora en los textos, más allá de su adhesión a los programas oficiales, información que denota un conocimiento más cercano de la región que se profundiza con el avance de las ediciones. Por un lado, refleja la visión nacional sobre los territorios y describe a la Patagonia por medio de imágenes contrapuestas que manifiestan en el espacio "lo civilizado y lo incivilizado e inexplorado", la belleza y la riqueza contra la infertilidad y la aridez. Por el otro, sus notas aclaratorias profundizan la información y nos acercan a una Patagonia con potencial productivo y futuro nacional, plasmando incluso la opinión de sus habitantes y de quienes la han recorrido: los mismos Salesianos In this work we analyze the Patagonia in the scholar books of Geography belonging to the Salesians (beginning of the XXth century). We observe this territorial construction as reflex and refraction of the social and political interests. About the treatment of these contents and the structuring we can see this region just in the difficult historical process of the incorporation to the Nation. The Congregation incorporates in these books, with official programs, information that denotes a special knowledge of the region in the different editions. These books reflect the national vision on the territories and describe the Patagonia with images that show the civilization, the no-civilization, the unexplored land, the beauty and the wealth, against the unfertility and the dryness. The notes in the text bring us information about Patagonia with productive potential and national future, capturing even the opinion of his inhabitants and the Salesians.
Los misioneros salesianos y la polémica sobre la extinción de los Selk’nam de Tierra del Fuego
María Andrea Nicoletti
Anthropologica , 2006,
Abstract: El proceso de extinción de los selk’nam generó una polémica dentro de la congregación de los salesianos alrededor de las causas que suscitaron su desaparición. Por medio de la reducción Nuestra Se ora de la Candelaria llevada a cabo por monse or Fagnano en 1893, se puso en marcha un plan de evangelización y civilización de los selk’nam. Estos aborígenes buscaban refugio en la reducción ante la persecución y asesinato perpetrados por los estancieros fueguinos. Las acechanzas, el contagio de enfermedades a las que los aborígenes no eran inmunes y el impacto cultural que provocó el sistema de reducciones, contribuyeron a su extinción. Los misioneros salesianos, protagonistas del proceso reduccional, analizaron las causas de la extinción poniendo el acento fundamentalmente en las matanzas de los estancieros y la violencia aplicada por las autoridades estatales, aun admitiendo las ocasionadas por el cambio cultural. La siguiente generación de salesianos, desde el estudio de las fuentes y la construcción de su propia historia, desplazó la causa violenta hacia motivos fisiológicos y culturales, con el fin de no poner en tela de juicio el rol que las familias de estancieros Braun Menéndez y Menéndez Behety, colaboradoras con la obra salesiana, tuvieron en este nefasto proceso.
Pressure-temperature phase diagram of charge ordering in Nd1/2Sr1/2MnO3
P. Maselli,D. Nicoletti,A. Nucara,F. M. Vitucci,A. Irizawa,K. Shoji,T. Nanba,P. Calvani
Physics , 2010, DOI: 10.1209/0295-5075/92/47001
Abstract: We observe how the charge-ordering (CO) temperature of Nd1/2Sr1/2MnO3 decreases with the external pressure p from 160 K at p = 0 down to 30 K at p ~ 4.5 GPa, by measuring the values p, T where the far-infrared spectral weight of the metallic phase is fully recovered. We thus determine the (p, T) phase diagram of CO in that manganite. We also find that the parameter d(lnTCO)/dp which describes this metallization from the CO phase is equal and opposite to the quantity d(lnTc)/dp which governs the metallization of the paramagnetic state at comparable Curie temperatures Tc, in similar manganites at half doping.
Infrared study of the charge-ordered multiferroic LuFe(2)O(4)
F. M. Vitucci,A. Nucara,D. Nicoletti,Y. Sun,C. H. Li,J. C. Soret,U. Schade,P. Calvani
Physics , 2010, DOI: 10.1103/PhysRevB.81.195121
Abstract: The reflectivity of a large LuFe(2)O(4) single crystal has been measured with the radiation field either perpendicular or parallel to the c axis of its rhombohedral structure, from 10 to 500K, and from 7 to 16000 cm-1. The transition between the two-dimensional and the three-dimensional charge order at T_(CO) = 320 K is found to change dramatically the phonon spectrum in both polarizations. The number of the observed modes above and below T_(CO), according to a factor-group analysis, is in good agreement with a transition from the rhombohedral space group R{bar 3}m to the monoclinic C2/m. In the sub-THz region a peak becomes evident at low temperature, whose origin is discussed in relation with previous experiments.
An optically stimulated superconducting-like phase in K3C60 far above equilibrium Tc
M. Mitrano,A. Cantaluppi,D. Nicoletti,S. Kaiser,A. Perucchi,S. Lupi,P. Di Pietro,D. Pontiroli,M. Riccò,A. Subedi,S. R. Clark,D. Jaksch,A. Cavalleri
Physics , 2015,
Abstract: The control of non-equilibrium phenomena in complex solids is an important research frontier, encompassing new effects like light induced superconductivity. Here, we show that coherent optical excitation of molecular vibrations in the organic conductor K3C60 can induce a non-equilibrium state with the optical properties of a superconductor. A transient gap in the real part of the optical conductivity and a low-frequency divergence of the imaginary part are measured for base temperatures far above equilibrium Tc=20 K. These findings underscore the role of coherent light fields in inducing emergent order.
Quasiparticle evolution and pseudogap formation in V2O3: An infrared spectroscopy study
L. Baldassarre,A. Perucchi,D. Nicoletti,A. Toschi,G. Sangiovanni,K. Held,M. Capone,M. Ortolani,L. Malavasi,M. Marsi,P. Metcalf,P. Postorino,S. Lupi
Physics , 2007, DOI: 10.1103/PhysRevB.77.113107
Abstract: The infrared conductivity of V2O3 is measured in the whole phase diagram. Quasiparticles appear above the Neel temperature TN and eventually disappear further enhancing the temperature, leading to a pseudogap in the optical spectrum above 425 K. Our calculations demonstrate that this loss of coherence can be explained only if the temperature dependence of lattice parameters is considered. V2O3 is therefore effectively driven from the metallic to the insulating side of the Mott transition as the temperature is increased.
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