929 research outputs found
First-order transitions and triple point on a random p-spin interaction model
The effects of competing quadrupolar- and spin-glass orderings are
investigated on a spin-1 Ising model with infinite-range random -spin
interactions. The model is studied through the replica approach and a phase
diagram is obtained in the limit . The phase diagram, obtained
within replica-symmetry breaking, exhibits a very unusual feature in magnetic
models: three first-order transition lines meeting at a commom triple point,
where all phases of the model coexist.Comment: 9 pages, 2 ps figures include
Differences between regular and random order of updates in damage spreading simulations
We investigate the spreading of damage in the three-dimensional Ising model
by means of large-scale Monte-Carlo simulations. Within the Glauber dynamics we
use different rules for the order in which the sites are updated. We find that
the stationary damage values and the spreading temperature are different for
different update order. In particular, random update order leads to larger
damage and a lower spreading temperature than regular order. Consequently,
damage spreading in the Ising model is non-universal not only with respect to
different update algorithms (e.g. Glauber vs. heat-bath dynamics) as already
known, but even with respect to the order of sites.Comment: final version as published, 4 pages REVTeX, 2 eps figures include
Uso múltiplo da água e lâminas de irrigação da bananeira FHIA 18 nas condições de semiárida.
Este trabalho objetivou avaliar a contribuição nutricional do uso múltiplo da água da piscicultura na irrigação da bananeira cv. Fhia 18. O experimento foi desenvolvido no Projeto Piloto de Fruticultura Irrigada do Vale de Parnaíba, localizado no município de Santa Rosa do Piauí, região semi-árida do Piauí
Machine-assisted Cyber Threat Analysis using Conceptual Knowledge Discovery
Over the last years, computer networks have evolved into highly dynamic and interconnected environments, involving multiple heterogeneous devices and providing a myriad of services on top of them. This complex landscape has made it extremely difficult for security administrators to keep accurate and be effective in protecting their systems against cyber threats. In this paper, we describe our vision and scientific posture on how artificial intelligence techniques and a smart use of security knowledge may assist system administrators in better defending their networks. To that end, we put forward a research roadmap involving three complimentary axes, namely, (I) the use of FCA-based mechanisms for managing configuration vulnerabilities, (II) the exploitation of knowledge representation techniques for automated security reasoning, and (III) the design of a cyber threat intelligence mechanism as a CKDD process. Then, we describe a machine-assisted process for cyber threat analysis which provides a holistic perspective of how these three research axes are integrated together
Ability-based view in action: a software corporation study
This research investigates antecedents, developments and consequences of dynamic capabilities in an organization. It contributes by searching theoretical and empirical answers to the questions: (a) What are the antecedents which can provide an organization with dynamic and ordinary capabilities?; (b) How do these antecedents contribute to create capabilities in an organization?; (c) How do they affect an organization's competitive advantage?; (d) Can we assess and measure the antecedents and consequences to an organization? From a first (theoretical) perspective, this paper searches answers to the first, second and third questions by reviewing concepts of an ability-based view of organizations that involves the abilities of cognition, intelligence, autonomy, learning and knowledge management, and which contributes to explain the dynamic behavior of the firm in the pursuit of competitive advantage. From a second (empirical) perspective, this paper reinforces and delivers findings to the second, third and fourth questions by presenting a case study that evidences the ability-based view in action in a software corporation, where it contributes by investigating: (a) the development of organizational capabilities; (b) the effects of the new capabilities on the organization; and (c) the assessment and measurement of the abilities and consequences
Efeito da adubação nitrogenada sobre os componentes de produção da mamoneira sob condições de estresse salino.
Construyendo el conocimiento agroecologico en asentamientos de la reforma agraria en la busqueda por la consolidación de un nuevo modelo de producción en elEestado de São Paulo, Brasil.
Duality in finite-dimensional spin glasses
We present an analysis leading to a conjecture on the exact location of the
multicritical point in the phase diagram of spin glasses in finite dimensions.
The conjecture, in satisfactory agreement with a number of numerical results,
was previously derived using an ansatz emerging from duality and the replica
method. In the present paper we carefully examine the ansatz and reduce it to a
hypothesis on analyticity of a function appearing in the duality relation. Thus
the problem is now clearer than before from a mathematical point of view: The
ansatz, somewhat arbitrarily introduced previously, has now been shown to be
closely related to the analyticity of a well-defined function.Comment: 12 pages, 3 figures; A reference added; to appear in J. Stat. Phy
Morphometric study of Acipenser nuccurii (Bonaparte, 1836) in fish farm individuals
The main objective of this study was to analyse differences and
similarities in morphometric characteristics among specimens of
the same year class of Acipenser naccarii (Bonaparte, 1836),
comparing fish raised either in Italy or Spain. All specimens were
F1 of captive broodstock in Italy.
Fifteen biometric variables were measured, and three derived
indices were calculated, on 30 individuals of 3+ year class from
Lombardy (Italy) and 90 individuals of I+, 2+ and 3+ year class
from Riofrio (Granada, Spain). A stepwise discriminate analysis
(SDA) was carried out, and the results were contrasted using a
non-hierarchical cluster analysis. The two groups proved to be
similar, so a principal component analysis and a simple
regression analysis were performed on all individuals, taking total
length (TI) as the independent variable and all the biometric
variables as dependent.
The study revealed that although the Soljan index (i.e. ratio of
mouth width to snout length) is related to TI, and is a valid
taxonomic characteristic, the CA index (i.e. relative position of
the barbels) and FB index (i.e. ratio of snout length to width) are also valid characteristics for individuals longer than 57 cm, being independent of TI
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