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Type 1 AGN and their Link to ULIRGS
Paola Andreani
Physics , 2001,
Abstract: Increasing observational evidence supports a picture for a close link among AGN phenomenum, star-formation processes and galaxy formation. Since the physical phenomena related to the onset of both AGN and star formation are very likely characterized by a strong far infrared (FIR) emission it becomes mandatory to investigate the FIR energy domain. However, because of their faintness in the FIR energy range, very little is known about the FIR properties of type 1 AGN, and type 2 AGN, which are supposed to be missed in classical searches, still lack definition and samples. Our aim is to investigate the FIR properties of optically selected type 1 AGN, compare them to Ultraluminous Infrared Galaxies (ULIRGs) and derive some general characteristics of the population. Expectations for future surveys are also presented.
ANALISIS FAKTOR-FAKTOR YANG MEMPENGARUHI HARGA SAHAM (Kasus Perusahaan Jasa Perhotelan yang Terdaftar di Pasar Modal Indonesia)
Edi Subiyantoro,Fransisca Andreani
Jurnal Manajemen dan Kewirausahaan , 2003,
Abstract: The study of testing the impact of several factors on stock price of hotel industry listed in Indonesia stock exchange is based on an approach to the constant growth of dividend discount model. By using regression analysis, this study provides evidence that stock price is influenced by book value equity per share and return on equity. The other factors of the research model such as return on asset (ROA), debt to equity ratio, stock return, market risk and return on the market index have no impact to the stock price. In general, it's discovered that all of the factors have weak influence in explaining stock price variation which means that mostly it is determined by other various things. Abstract in Bahasa Indonesia : Penelitian terhadap pengaruh beberapa faktor yang mempengaruhi harga saham perusahaan jasa perhotelan yang terdaftar di pasar modal Indonesia didasarkan atas suatu pendekatan terhadap pertumbuhan tetap dari devidend discount model. Dengan menggunakan analisa regresi maka diketahui bahwa harga saham dipengaruhi oleh book value equity per share dan return on equity. Faktor-faktor lain seperti return on asset (ROA), debt to equity ratio, stock return, market risk dan return on the market index ternyata tidak berpengaruh terhadap harga saham. Secara umum, dapat dikatakan bahwa faktor-faktor tersebut mempunyai pengaruh yang relatif lemah terhadap variasi harga saham. Ini berarti bahwa variasi harga saham ditentukan oleh faktor-faktor lainnya. Kata kunci: harga saham, equity, return on asset (ROA
1.25 mm Observations of a Complete Sample of IRAS Galaxies: (II) Dust Properties
P. Andreani,A. Franceschini
Physics , 1996, DOI: 10.1093/mnras/283.1.85
Abstract: We present 1.25 mm continuum data for a southern galaxy sample selected from the IRAS PSC and complete to S_60=2 Jy. Two thirds of the galaxies have been detected and significant limits on the remaining objects have been set. We find, on a statistical basis, indications that the dust emission in these galaxies is somewhat more centrally concentrated than that of the optical light, possibly tracing a higher metal content in the inner galactic regions. This result also allows to estimate the aperture corrections to the millimetric data. The latter, together with IRAS photometric data, have been used to compare the broad-band FIR/mm spectra with a simple dust model. According to their far-IR/mm spectrum, the sample galaxies show a dichothomy: almost half of the objects, those displaying bright 25-60um fluxes ascribed to warm dust residing in 'starburst' regions, are characterized by higher values of the bolometric (optical + FIR) luminosity, of the dust-to-gas mass ratio, of the dust optical depths and of the overall extinction. A complementary class of objects dominated by cold dust ('cirrus') shows opposite trends. Because of the favourable observational setup, selection wavelength and completeness, we believe these data provide an exhaustive and unbiased view of dust properties in spiral galaxies.
MM Observations of IRAS Galaxies: Dust Properties, Luminosity Functions and Contributions to the Sub-MM Background
P. Andreani,A. Franceschini
Physics , 1996,
Abstract: We have studied the FIR/{\it mm} spectrum of IR galaxies by combining IRAS photometry with new {\it mm} data on a complete southern IRAS galaxy sample. The observed spectra and a dust model emphasize a dicothomy in the galaxy population: half of the objects with a lot of warm dust are characterized by higher values of the bolometric (UV-FIR) luminosity, of the dust-to-gas mass ratio, of the dust optical depths and extinction, while those dominated by cold ({\it cirrus}) dust show opposite trends. From these data we derive the {\it mm} luminosity function of galaxies and estimate their contribution to the sub-{\it mm} background (BKG).
Millimeter Observations of a Complete Sample of IRAS Galaxies: Dust Emission and Absorption in Spirals
A. Franceschini,P. Andreani
Physics , 1994, DOI: 10.1086/187747
Abstract: We report on observations performed at 1.25 $mm$ of a southern galaxy sample, selected from the IRAS PSC and complete to $S_{60}=2 Jy$. We detected 18 sources and set significant limits on 10 further objects. We use these data to discuss the spatial distribution of cold dust, the broad-band far-IR/mm spectra, the overall amount of dust, the gas-to-dust mass ratio, the dust optical depth, and the overall extinction, for such a representative galaxy sample. These results are also supported by a successful comparison with values inferred for the Galaxy. Because of the favourable observational setup, selection wavelength and completeness, we believe these data provide an unbiased view of dust properties in spiral galaxies.
Considerations on some neglected but impotant issues concerning the In ternal Linear Combination method in Astronomy
R. Vio,P. Andreani
Physics , 2009,
Abstract: Although the ``internal linear'' combination method (ILC) is a technique widely used for the separation of the Cosmic Microwave Background signal from the Galactic foregrounds, its characteristics are not yet well defined. This can lead to misleading conclusions about the actual potentialities and limits of such approach in real applications. Here we discuss briefly some facts about ILC that to our knowledge are not fully worked out in literature and yet have deep effects in the interpretation of the results.
Use of ionic liquids in biodiesel production: a review
Andreani, L.;Rocha, J. D.;
Brazilian Journal of Chemical Engineering , 2012, DOI: 10.1590/S0104-66322012000100001
Abstract: this paper discusses the feasibility of the use of ionic liquids as catalysts in the biodiesel production field, describing some studies already published in the literature on this theme. ionic liquids are regarded as a new generation of catalysts in the chemical industry, with several uses in different commercial segments. however only a few publications involving this topic can be found in the literature addressing the manufacture of biodiesel from vegetable oils or animal fats. through the analysis of the data generated in the studies reviewed, it is possible to affirm that ionic liquids present great potential as catalysts for biodiesel production, but there are some challenges to be faced, such as the production of ionic liquids with low cost, easy recovery and with the possibility of reutilization of the catalyst for several cycles.
Quantum theory of spontaneous emission in multilayer dielectric structures
Celestino Creatore,Lucio Claudio Andreani
Physics , 2008, DOI: 10.1103/PhysRevA.78.063825
Abstract: We present a fully quantum-electrodynamical formalism suitable to evaluate the spontaneous emission rate and pattern from a dipole embedded in a non-absorbing and lossless multilayer dielectric structure. In the model here developed the electromagnetic field is quantized by a proper choice of a complete and orthonormal set of classical spatial modes, which consists of guided and radiative (partially and fully) states. In particular, by choosing a set of radiative states characterized by a single outgoing component, we get rid of the problem related to the quantum interference between different outgoing modes, which arises when the standard radiative basis is used to calculate spontaneous emission patterns. After the derivation of the local density of states, the analytical expressions for the emission rates are obtained within the framework of perturbation theory. First we apply our model to realistic Silicon-based structures such as a single Silicon/air interface and a Silicon waveguide in both the symmetric and asymmetric configurations. Then, we focus on the analysis of the spontaneous emission process in a silicon-on-insulator (SOI) Slot waveguide (a 6 layers model structure) doped with erbium ions (emitting at the telecom wavelength). In this latter case we find a very good agreement with the experimental evidence [M. Galli et al., Appl. Phys. Lett. 89, 241114 (2006)] of an enhanced TM/TE photoluminescence signal. Hence, this model is relevant to study the spontaneous emission in Silicon-based multilayer structures which nowadays play a fundamental role for the development of highly integrated multifunctional devices.
Etched distributed Bragg reflectors as three-dimensional photonic crystals: photonic bands and density of states
E. Pavarini,L. C. Andreani
Physics , 2002, DOI: 10.1103/PhysRevE.66.036602
Abstract: The photonic band dispersion and density of states (DOS) are calculated for the three-dimensional (3D) hexagonal structure corresponding to a distributed Bragg reflector patterned with a 2D triangular lattice of circular holes. Results for the Si/SiO$_2$ and GaAs/AlGaAs systems determine the optimal parameters for which a gap in the 2D plane occurs and overlaps the 1D gap of the multilayer. The DOS is considerably reduced in correspondence with the overlap of 2D and 1D gaps. Also, the local density of states (i.e., the DOS weighted with the squared electric field at a given point) has strong variations depending on the position. Both results imply substantial changes of spontaneous emission rates and patterns for a local emitter embedded in the structure and make this system attractive for the fabrication of a 3D photonic crystal with controlled radiative properties.
Josephson surface plasmons in spatially confined cuprate superconductors
Filippo Alpeggiani,Lucio Claudio Andreani
Physics , 2013, DOI: 10.1103/PhysRevB.88.174513
Abstract: In this work, we generalize the theory of localized surface plasmons to the case of high-Tc cuprate superconductors, spatially confined in the form of small spherical particles. At variance from ordinary metals, cuprate superconductors are characterized by a low-energy bulk excitation known as the Josephson plasma wave (JPW), arising from interlayer tunneling of the condensate along the c-axis. The effect of the JPW is revealed in a characteristic spectrum of surface excitations, which we call Josephson surface plasmons. Our results, which apply to any material with a strongly anisotropic electromagnetic response, are worked out in detail for the case of multilayered superconductors supporting both low-frequency (acoustic) and transverse-optical JPW. Spatial confinement of the Josephson plasma waves may represent a new degree of freedom to engineer their frequencies and to explore the link between interlayer tunnelling and high-Tc superconductivity.
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