5,554 research outputs found

    Normalizing Database Normalization Definitions In AIS Text Books

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    Due to the abstract nature of the definitions for normal forms, over the years the interpretations of the definitions published in the textbooks, both MIS and AIS disciplines, have been differentiated and even deviated from its original form. The concept of deviation from the original form is a phenomenon that linguists call “semantic drift.” The most noticeable deviations are on first and second normal forms (i.e., 1NF and 2NF). Their definitions range from “atomic attribute” to “removing repeating group” for 1NF and from “functional dependency” to “removing partial dependency” in addition to being 1NF for 2NF. The purpose of this paper is to compare definitions of first, second, and third normal forms from the textbooks with those of the earlier forms and to identify shortfalls if there are any

    Normalisasi Dalam Perancangan Basis Data Relasional Purchase Order (PO)

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    Abstrak: Basis data merupakan koleksi terpadu dari data yang saling terintegrasi dengan tujuan untuk kecepatan dalam pengambilan kembali data untuk memenuhi kebutuhan end user suatu perusahaan. Dalam melakukan perancangan basis data dapat dilakukan dengan menggunakan 2 (dua) pendekatan yaitu dengan melakukan normalisasi atau dengan konsep ERD (Entity Relationship Diagram). Normalisasi merupakan teknik formal yang digunakan dalam perancangan basis data untuk menghasilkan rancangan basis data yang optimal yang bebas anomali (insert, update dan delete). Dalam perancangan basis data dengan  normalisasi menggunakan kasus data Purchase Order (PO). Dalam normalisasi dilakukan dengan melakukan Unnormalized Form (UNF), First Normal Form  (1 NF), Second Normal Form (2NF), Thirt Normal Form (3NF) sampai terbentuknya ERD (Entity Relationship Diagram) dan terbentuknya perancangan struktur tabel dari tabel-tabel yang terbentuk dari hasil normalisasi.   Kata Kunci: Anomali, Entity Relationship Diagram, Normalisasi.   Abstract: A database is an integrated collection of data are integrated with the purpose to speed in taking back the data to meet the needs of the end user of a company. When doing database design can be done by using 2 (two) approach is to perform normalization or with the concept of an ERD (Entity Relationship Diagram). Normalization is a formal technique used in designing the database to produce an optimal database design that is free of anomalies (insert, update, and delete). In the design of data base with normalization using case data Purchase Order (PO). In the normalization is performed by doing the Unnormalized Form (EXTRACT), the First Normal Form (1 NF), Second Normal Form (2NF), Thirt Normal Form (3NF) until the formation of the ERD (Entity Relationship Diagrams) and the formation of table structure design tables of results of normalization.  Keywords: Anomalies, Entity Relationship Diagram, Normalization

    Thermodynamics of chiral symmetry at low densities

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    The phase diagram of two-color QCD as a function of temperature and baryon chemical potential is considered. Using a low-energy chiral Lagrangian based on the symmetries of the microscopic theory, we determine, at the one-loop level, the temperature dependence of the critical chemical potential for diquark condensation and the temperature dependence of the diquark condensate and baryon density. The prediction for the temperature dependence of the critical chemical potential is consistent with the one obtained for a dilute Bose gas. The associated phase transition is shown to be of second order for low temperatures and first order at higher temperatures. The tricritical point at which the second order phase transition ends is determined. The results are carried over to QCD with quarks in the adjoint representation and to ordinary QCD at a non-zero chemical potential for isospin.Comment: 29 pages, Latex, typos corrected, 1 Ref added. Version to appear in Nucl. Phys.

    Diquark Condensate in QCD with Two Colors at Next-to-Leading Order

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    We study QCD with two colors and quarks in the fundamental representation at finite baryon density in the limit of light quark masses. In this limit the free energy of this theory reduces to the free energy of a chiral Lagrangian which is based on the symmetries of the microscopic theory. In earlier work this Lagrangian was analyzed at the mean field level and a phase transition to a phase of condensed diquarks was found at a chemical potential of half the diquark mass (which is equal to the pion mass). In this article we analyze this theory at next-to-leading order in chiral perturbation theory. We show that the theory is renormalizable and calculate the next-to-leading order free energy in both phases of the theory. By deriving a Landau-Ginzburg theory for the order parameter we show that the finite one-loop contribution and the next-to-leading order terms in the chiral Lagrangian do not qualitatively change the phase transition. In particular, the critical chemical potential is equal to half the next-to-leading order pion mass, and the phase transition is second order.Comment: 29 pages, 2 figure

    Coherence in the Quasi-Particle 'Scattering' by the Vortex Lattice in Pure Type-II Superconductors

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    The effect of quasi-particle (QP) 'scattering' by the vortex lattice on the de-Haas van-Alphen oscillations in a pure type-II superconductor is investigated within mean field,asymptotic perturbation theory. Using a 2D electron gas model it is shown that, due to a strict phase coherence in the many-particle correlation functions, the 'scattering' effect in the asymptotic limit (EF/ωc1\sqrt{E_F/\hbar\omega_c}\gg 1) is much weaker than what is predicted by the random vortex lattice model proposed by Maki and Stephen, which destroys this coherence . The coherent many particle configuration is a collinear array of many particle coordinates, localized within a spatial region with size of the order of the magnetic length. The amplitude of the magnetization oscillations is sharply damped just below % H_{c2} because of strong 180180^{\circ} out of phase magnetic oscillations in the superconducting condensation energy ,which tend to cancel the normal electron oscillations. Within the ideal 2D model used it is found, however, that because of the relative smallness of the quartic and higher order terms in the expansion, the oscillations amplitude at lower fields does not really damp to zero, but only reverses sign and remains virtually undamped well below Hc2H_{c2}. This conclusion may be changed if disorder in the vortex lattice, or vortex lines motion will be taken into account. The reduced QP 'scattering' effect may be responsible for the apparent crossover from a strong damping of the dHvA oscillations just below Hc2H_{c2} to a weaker damping at lower fields observed experimentally in several 3D superconductors.Comment: 26 pages, Revtex no Figure

    Notes on Ricci solitons in ff-cosymplectic manifolds

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    The purpose of this article is to study an ff-cosymplectic manifold MM admitting Ricci solitons. Here we consider mainly two classes of Ricci solitons on ff-cosymplectic manifolds. One is the class of contact Ricci solitons. The other is the class of gradient Ricci solitons, for which we give the local classifications of MM. Meanwhile, we also give some properties of ff-cosymplectic manifolds

    Analytical treatment of interacting Fermi gas in arbitrary dimensional harmonic trap

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    We study normal state properties of an interacting Fermi gas in an isotropic harmonic trap of arbitrary dimensions. We exactly calculate the first-order perturbation terms in the ground state energy and chemical potential, and obtain simple analytic expressions of the total energy and chemical potential. At zero temperature, we find that Thomas-Fermi approximation agrees well with exact results for any dimension even though system is dilute and small, i.e. when the Thomas-Fermi approximation is generally expected to fail. In the high temperature (classical) region, we find interaction energy decreases in proportion to T^(-d/2), where T is temperature and d is dimension of the system. Effect of interaction in the ground state in two and three-dimensional systems is also discussed.Comment: 15 pages, 4 figure
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