334 research outputs found

    SOFTWARE DEVELOPMENT BUSINESS MOVING TOWARDS A UNIFIED COLLABORATIVE SYSTEM IN IT. SAAS MAY BE THE NEW ORIENTATION.

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    In this paper we will present an alternative way of programming. Our opinion is that, in the next few years, software development business will suffer serious changes. Software vendors will adopt SaaS (Software as a Service) as the new way of selling their products. We will try to guide you through the basic concepts of this relatively new domain. The article also includes a brief description of an application, developed indoor but using SaaS applications for some of its modules. In the end we want to make an SWOT analysis of the opportunity of using SaaS.Software as a service (SaaS), informatics, business, vendors, new technology.

    The Design of a Distributed Database for Doctoral Studies Management

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    This paper aims to create a system that manages doctoral school requirements. The management of doctoral school implies administration of information like PhD personal information, Supervisors, Teachers, and other information that may be useful. We will debate on distributed database term as the proposed database project will have the same structure for four universities. Each university will be able to work on this database by accessing its own set of data and properly using the information received. This project will track the creation of a database to manage all the information needed and provide answers using these data.Distributed Database, Fragmentation, Top-Down Design Process

    Mesoscopic Fano Effect in a spin splitter with a side-coupled quantum dot

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    Cataloged from PDF version of article.We investigate the interplay between the spin interference and the Fano effect in a three-lead mesoscopic ring with a side-coupled quantum dot (QD). A uniform Rashba spin-orbit coupling and a perpendicular magnetic field are tuned such that the ring operates as a spin splitter in the absence of the QD: one lead is used to inject unpolarized electrons and the remaining (output) leads collect almost polarized spin currents. By applying a gate potential to the quantum dot a pair of spin-split levels sweeps the bias window and leads to Fano interference. The steady-state spin and charge currents in the leads are calculated for a finite bias applied across the ring via the non-equilibrium Green's function formalism. When the QD levels participate to transport we find that the spin currents exhibit peaks and dips whereas the charge currents present Fano lineshapes. The location of the side-coupled quantum dot and the spin splitting of its levels also affect the interference and the output currents. The opposite response of output currents to the variation of the gate potential allows one to use this system as a single parameter current switch. We also analyze the dependence of the splitter efficiency on the spin splitting on the QD. (C) 2012 Elsevier B.V. All rights reserved

    An Ultraviolet Study of Star-Forming Regions in M31

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    We present a comprehensive study of star-forming (SF) regions in the nearest large spiral galaxy M31. We use GALEX far-UV (1344-1786 \AA, FUV) and near-UV (1771-2831 \AA, NUV) imaging to detect young massive stars and trace the recent star formation across the galaxy. The FUV and NUV flux measurements of the SF regions, combined with ground-based data for estimating the reddening by interstellar dust from the massive stars they contain, are used to derive their ages and masses. The GALEX imaging, combining deep sensitivity and coverage of the entire galaxy, provides a complete picture of the recent star formation in M31 and its variation with environment throughout the galaxy. The FUV and NUV measurements are sensitive to detect stellar populations younger than a few hundred Myrs. We detected 894 SF regions, with size > 1600 pc^{2} above an average FUV flux limit of ~ 26 ABmag arcsecond^{-2}, over the whole 26 kpc galaxy disk. We derive the star-formation history of M31 within this time span. The star formation rate (SFR) from the youngest UV sources (age < 10 Myr) is comparable to that derived from H_{alpha}, as expected. We show the dependence of the results on the assumed metallicity. When star formation detected from IR measurements of the heated dust is added to the UV-measured star formation (from the unobscured populations) in the recent few Myrs, we find the SFR has slightly decreased in recent epochs, with a possible peak between 10 and 100 Myrs, and an average value of SFR ~ 0.6 or 0.7 M_{sun} yr^{-1} (for metallicity Z=0.02 or 0.05 respectively) over the last 400 Myrs.Comment: 39 pages, 14 figures, accepted for publication in ApJ, high resolution version available at this http://dolomiti.pha.jhu.edu/papers/2009_KangBianchiRey.pd

    The Compact Structure of Radio-Loud Broad Absorption Line Quasars

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    We present the results of EVN+MERLIN VLBI polarization observations of 8 Broad Absorption Line (BAL) quasars at 1.6 GHz, including 4 LoBALs and 4 HiBALs with either steep or flat spectra on VLA scales. Only one steep-spectrum source, J1122+3124, shows two-sided structure on the scale of 2 kpc. The other four steep-spectrum sources and three flat-spectrum sources display either an unresolved image or a core-jet structure on scales of less than three hundred parsecs. In all cases the marginally resolved core is the dominant radio component. Linear polarization in the cores has been detected in the range of a few to 10 percent. Polarization, together with high brightness temperatures (from 2*10^9-5*10^10 K), suggest a synchrotron origin for the radio emission. There is no apparent difference in the radio orphologies or polarization between low-ionization and high-ionization BAL QSOs nor between flat- and steep-spectrum sources. We discuss the orientation of BAL QSOs with both flat and steep spectra, and consider a possible evolutionary scenario for BAL QSOs. In this scenario, BAL QSOs are probably the young population of radio sources, which are Compact Steep Spectrum or GHz peaked radio source analog at the low end of radio power.Comment: 16 pages, 3 figures, 4 tables; accepted for publication in MNRA
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