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Search Results: 1 - 10 of 770 matches for " Giuliano Bellieni "
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Rapakivi texture in porphyritic dikes within the Karavanke Granitic Massif (Slovenia)
Meta Dobnikar,Tadej Dolenec,Giuliano Bellieni
Bulletin of the Geological Society of Finland , 2002,
Abstract: The northern Karavanke Granitic Massif straddles the Slovenian–Austrian border. The investigated area lies in northern Slovenia, and extends from the western Slovenian–Austrian border to the east for about 30 km, with a maximum width of 2 km. The massif exhibits a bimodal magmatic association comprising mainly syenogranite and syenite with contemporaneous gabbroic rocks. Rocks of intermediate composition are less abundant and show field, textural and chemical features suggesting that they have formed as a result of the interaction (mixing and mingling) between felsic and mafic magmas. Plagioclasemantled alkali feldspars occur in dikes of porphyritic syenite, which cut larger bodies of gabbroic rocks. Field, mineralogical, petrographic and geochemical evidences suggest that the porphyritic syenite is a hybrid rock, formed by the interaction of mafic and felsic magmas. The formation of plagioclase-mantled alkali feldspar can be explained by the introduction of alkali feldspar from felsic, syenogranitic magma into more mafic magma, causing local undercooling in the portion of mafic magma surrounding the crystals. This resulted in the growth of cellular plagioclase, with quartz infilling, in a thermally and compositionally equilibrating system.
Chemical composition as a criterion in identifying tourmalines from the Ravne pegmatite and surrounding metapelites, Slovenia
Petra Souvent,Anna M. Fioretti,Giuliano Bellieni,Tadej Dolenec
Geologija , 2000,
Análisis estadístico de datos geoquímicos de volcanitas jurásicas del Macizo del Deseado, provincia de Santa Cruz Statistical analysis of geochemical data from Jurassic volcanic rocks of the Deseado Massif, province of Santa Cruz
M. Alperin,H. Echeveste,R. Fernández,G. Bellieni
Revista de la Asociación Geológica Argentina , 2007,
Abstract: Durante el mapeo de detalle de la zona central del macizo del Deseado se reconoció un conjunto de unidades volcánicas jurásicas: lavas e ignimbritas de composición andesítica, dacítica y riolítica. Se realizó un análisis estadístico de los óxidos mayoritarios SiO2, TiO2, Al2O3, FeO (total), MnO, MgO, CaO, Na2O, K2O y P2O5 de 73 muestras provenientes de ocho unidades volcánicas. La composición geoquímica total constituye un conjunto de datos cerrados o datos composicionales ya que la suma de las partes para cada muestra es un valor fijo de 100%. Para analizar las relaciones entre óxidos, entre unidades volcánicas y para examinar la existencia de subpoblaciones se emplearon gráficos de dos dimensiones de datos composicionales como herramienta exploratoria, análisis de agrupamiento entre muestras y métodos de inferencia estadística. Los resultados hallados permitieron: (a) Constatar la existencia de dos grupos de unidades volcánicas, uno constituido casi exclusivamente por riolitas y otro formado principalmente por andesitas y dacitas. Si bien el primer grupo reúne volcanitas que podrían incluirse en la Formación Chon Aike, las unidades volcánicas del segundo grupo no se ajustan a ninguna de las unidades formacionales definidas para el volcanismo jurásico de esta región. (b) Definir subgrupos de muestras que se ajustan estrechamente a las unidades volcánicas reconocidas, lo que indica la marcada relación entre estas y sus respectivas composiciones químicas. (c) Confirmar la ausencia de un intervalo (gap) composicional evidenciado en los diagramas TAS y AFM. (d) Indicar como más adecuado el mapeo de detalle de unidades litológicas (volcánicas) y/o litofaciales que el de formaciones ya que permite una mejor reconstrucción de la evolución del volcanismo de la región. During the detailed mapping of the central zone of the Deseado Massif, a group of Jurassic volcanic units consisting of lavas and ignimbrites of andesitic, dacitic and rhyolitic composition was identified. A statistical analysis of major oxides SiO2, TiO2, Al2O3, FeO (total), MnO, MgO, CaO, Na2O, K2O y P2O5 from 73 samples originated from eight volcanic units was conducted. The total geochemical composition of each sample constitutes a closed set of data (or set of compositional data) as the sum of each sample's part is 100%. To analyze the relationships between oxides, between volcanic units, and to identify the existence of subsets, compositional biplots were used as an exploratory tool. In addition, cluster analysis of the samples and statistical inference were performed. The results allowed f
Volumetric Breast Ultrasound as a Screening Modality in Mammographically Dense Breasts
Vincenzo Giuliano,Concetta Giuliano
ISRN Radiology , 2013, DOI: 10.5402/2013/235270
Abstract: This investigation is part of an ongoing large scale study using volumetric breast ultrasound (VBUS) as a screening modality in mammographically dense breasts, offering a substantial benefit to MR imaging of the breast in terms of cost and efficiency. The addition of VBUS to mammography in women with greater than 50% breast density resulted in the detection of 12.3 per 1,000 breast cancers, compared to 4.6 per 1,000 by mammography alone with an overall attributable risk of breast cancer of 19.92 (95% confidence level, 16.75–23.61) in our screened population. These preliminary results may justify the cost benefit of implementing the judicious use of VBUS as an alternative to MR imaging of the breast in conjunction with mammography in the dense breast screening population. 1. Introduction Mammographic density as an independent risk factor for developing breast cancer has been documented since the 1970s [1]. The appearance of breast tissue is variable among women. The appearance of density on mammography is the result of the relative proportion of breast stroma, which is less radiolucent compared to fat, accounting for increased breast density. Wolfe classified breast density as an independent risk factor for breast cancer in women [2, 3]. Approximately 70 to 80% of breast cancers occur in women with no major predictors [4–6]. Population-based screening for early detection of breast cancer is therefore the primary strategy for reducing breast cancer mortality. Mammography has been used as the standard imaging method for breast cancer screening, with reduction in breast cancer mortality [7]. Computer-aided detection (CAD) technology with full-field digital mammography (FFDM) has been shown to have several advantages over screen-film mammography, including higher contrast resolution, better dynamic range, and lower noise [8, 9]. Previous studies have shown that CAD performance is similar for the detection of cancer in fatty breasts and dense breasts with screen-film mammography (90% versus 88%, resp.; ) [10] and with FFDM (95% versus 98%; ) [11]. Sensitivity in extremely dense breasts was only 60% [12]. There are numerous studies showing that CAD performance is limited by background parenchymal breast density, where the sensitivity of the detection of breast masses sensitivity is significantly higher for fatty breasts than for dense breasts [11, 13–15]. Breast density significantly reduces the ability to visualize cancers on mammography. All false-negative lesions detected with CAD manifested as masses [16]. The number of missed cancers is substantially
A simple representation of quantum process tomography
Giuliano Benenti,Giuliano Strini
Physics , 2009, DOI: 10.1103/PhysRevA.80.022318
Abstract: We show that the Fano representation leads to a particularly simple and appealing form of the quantum process tomography matrix $\chi_{_F}$, in that the matrix $\chi_{_F}$ is real, the number of matrix elements is exactly equal to the number of free parameters required for the complete characterization of a quantum operation, and these matrix elements are directly related to evolution of the expectation values of the system's polarization measurements. These facts are illustrated in the examples of one- and two-qubit quantum noise channels.
Computing the distance between quantum channels: Usefulness of the Fano representation
Giuliano Benenti,Giuliano Strini
Physics , 2010, DOI: 10.1088/0953-4075/43/21/215508
Abstract: The diamond norm measures the distance between two quantum channels. From an operational vewpoint, this norm measures how well we can distinguish between two channels by applying them to input states of arbitrarily large dimensions. In this paper, we show that the diamond norm can be conveniently and in a physically transparent way computed by means of a Monte-Carlo algorithm based on the Fano representation of quantum states and quantum operations. The effectiveness of this algorithm is illustrated for several single-qubit quantum channels.
Optimal purification of a generic n-qudit state
Giuliano Benenti,Giuliano Strini
Physics , 2008, DOI: 10.1103/PhysRevA.79.052301
Abstract: We propose a quantum algorithm for the purification of a generic mixed state $\rho$ of a $n$-qudit system by using an ancillary $n$-qudit system. The algorithm is optimal in that (i) the number of ancillary qudits cannot be reduced, (ii) the number of parameters which determine the purification state $|\Psi>$ exactly equals the number of degrees of freedom of $\rho$, and (iii) $|\Psi>$ is easily determined from the density matrix $\rho$. Moreover, we introduce a quantum circuit in which the quantum gates are unitary transformations acting on a $2n$-qudit system. These transformations are determined by parameters that can be tuned to generate, once the ancillary qudits are disregarded, any given mixed $n$-qudit state.
Gaussian wave packets in phase space: The Fermi g_F function
Giuliano Benenti,Giuliano Strini
Physics , 2008, DOI: 10.1119/1.3083268
Abstract: Any pure quantum state can be equivalently represented by means of its wave function psi(q) or of the Fermi function g_F(q,p), with q and p coordinates and conjugate momenta of the system under investigation.We show that a Gaussian wave packet can be conveniently visualized in phase space by means of the curve g_F(q,p)=0. The evolution in time of the g_F=0 curve is then computed for a Gaussian packet evolving freely or under a constant or a harmonic force. As a result, the spreading or shrinking of the packet is easily interpreted in phase space. Finally, we discuss a gedanken prism microscope experiment for measuring the position-momentum correlation. This gedanken experiment, together with the well-known Heisenberg microscope and von Neumann velocimeter, is sufficient to fully determine the state of a Gaussian packet.
Quantum simulation of the single-particle Schrodinger equation
Giuliano Benenti,Giuliano Strini
Physics , 2007, DOI: 10.1119/1.2894532
Abstract: The working of a quantum computer is described in the concrete example of a quantum simulator of the single-particle Schrodinger equation. We show that a register of 6-10 qubits is sufficient to realize a useful quantum simulator capable of solving in an efficient way standard quantum mechanical problems.
A bird's eye view of quantum computers
Giuliano Benenti,Giuliano Strini
Physics , 2007,
Abstract: Quantum computers are discussed in the general framework of computation, the laws of physics and the foundations of quantum mechanics.
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