9,050 research outputs found
Recommended from our members
An ontology to model the research process in information systems
The IS community has relied mostly on two main paradigms to undertake IS research: positivist and interpretivist. This paper argues that the ongoing debate around which of these paradigms is better suited to undertake IS research has created confusion amongst IS researchers, particularly between those who are relatively inexperienced (e.g. PhD researchers). Inexperienced researchers tend to place emphasis on the justification of their research approaches in the context of existing paradigms without offering a clear description of how the chosen methods and paradigms are applied in the context of their own research, a key issue to assess and understand any research output. This paper does not attempt to give any suggestions as to which research methods/paradigms should be used for IS research, but to raise the awareness that the way we currently communicate our thoughts in the research methods domain may not be very effective. We argue that an initial step to undertake this challenge could be to take a more “practical” approach by focusing on the process of thinking and planning the research activity rather than focusing on the justification of the use of one or many research methods usually “loaned” from other discipline
Two-time Green's functions and spectral density method in nonextensive quantum statistical mechanics
We extend the formalism of the thermodynamic two-time Green's functions to
nonextensive quantum statistical mechanics. Working in the optimal Lagrangian
multipliers representation, the -spectral properties and the methods for a
direct calculation of the two-time % -Green's functions and the related
-spectral density ( measures the nonextensivity degree) for two generic
operators are presented in strict analogy with the extensive ()
counterpart. Some emphasis is devoted to the nonextensive version of the less
known spectral density method whose effectiveness in exploring equilibrium and
transport properties of a wide variety of systems has been well established in
conventional classical and quantum many-body physics. To check how both the
equations of motion and the spectral density methods work to study the
-induced nonextensivity effects in nontrivial many-body problems, we focus
on the equilibrium properties of a second-quantized model for a high-density
Bose gas with strong attraction between particles for which exact results exist
in extensive conditions. Remarkably, the contributions to several thermodynamic
quantities of the -induced nonextensivity close to the extensive regime are
explicitly calculated in the low-temperature regime by overcoming the
calculation of the grand-partition function.Comment: 48 pages, no figure
Spectral density method in quantum nonextensive thermostatistics and magnetic systems with long-range interactions
Motived by the necessity of explicit and reliable calculations, as a valid
contribution to clarify the effectiveness and, possibly, the limits of the
Tsallis thermostatistics, we formulate the Two-Time Green Functions Method in
nonextensive quantum statistical mechanics within the optimal Lagrange
multiplier framework, focusing on the basic ingredients of the related Spectral
Density Method. Besides, to show how the SDM works we have performed, to the
lowest order of approximation, explicit calculations of the low-temperature
properties for a quantum -dimensional spin-1/2 Heisenberg ferromagnet with
long-range interactions decaying as ( is the distance between
spins in the lattice)Comment: Contribution to Next-SigmaPhi conference in Kolymbari, Crete, Greece,
August 13-18, 2005, 9 page
The Classical Spectral Density Method at Work: The Heisenberg Ferromagnet
In this article we review a less known unperturbative and powerful many-body
method in the framework of classical statistical mechanics and then we show how
it works by means of explicit calculations for a nontrivial classical model.
The formalism of two-time Green functions in classical statistical mechanics is
presented in a form parallel to the well known quantum counterpart, focusing on
the spectral properties which involve the important concept of spectral
density. Furthermore, the general ingredients of the classical spectral density
method (CSDM) are presented with insights for systematic nonperturbative
approximations to study conveniently the macroscopic properties of a wide
variety of classical many-body systems also involving phase transitions. The
method is implemented by means of key ideas for exploring the spectrum of
elementary excitations and the damping effects within a unified formalism.
Then, the effectiveness of the CSDM is tested with explicit calculations for
the classical -dimensional spin- Heisenberg ferromagnetic model with
long-range exchange interactions decaying as () with distance
between spins and in the presence of an external magnetic field. The analysis
of the thermodynamic and critical properties, performed by means of the CSDM to
the lowest order of approximation, shows clearly that nontrivial results can be
obtained in a relatively simple manner already to this lower stage. The basic
spectral density equations for the next higher order level are also presented
and the damping of elementary spin excitations in the low temperature regime is
studied. The results appear in reasonable agreement with available exact ones
and Monte Carlo simulations and this supports the CSDM as a promising method of
investigation in classical many-body theory.Comment: Latex, 58 pages, 12 figure
Low-Temperature Quantum Critical Behaviour of Systems with Transverse Ising-like Intrinsic Dynamics
The low-temperature properties and crossover phenomena of -dimensional
transverse Ising-like systems within the influence domain of the quantum
critical point are investigated solving the appropriate one-loop
renormalization group equations. The phase diagram is obtained near and at
and several sets of critical exponents are determined which describe
different responses of a system to quantum fluctuations according to the way of
approaching the quantum critical point. The results are in remarkable agreement
with experiments for a wide variety of compounds exhibiting a quantum phase
transition, as the ferroelectric oxides and other displacive systems.Comment: 36 pages, 2 figures, accepted in Physica
Assessment of the radiological impact of a decommissioning nuclear power plant in Italy
The assessment of the radiological impact of a decommissioning Nuclear Power
Plant is presented here through the results of an environmental monitoring
survey carried out in the area surrounding the Garigliano Power Plant. The
levels of radioactivity in soil, water, air and other environmental matrices
are shown, in which {\alpha}, {\beta} and {\gamma} activity and {\gamma}
equivalent dose rate are measured. Radioactivity levels of the samples from the
Garigliano area are analyzed and then compared to those from a control zone
situated more than 100 km away. Moreover, a comparison is made with a previous
survey held in 2001. The analyses and comparisons show no significant
alteration in the radiological characteristics of the area surroundings the
plant, with an overall radioactivity depending mainly from the global fallout
and natural sources.Comment: 13 pages, 6 figures, 2 table
Assessment of the radiological impact of a decommissioning nuclear power plant in Italy
The assessment of the radiological impact of a decommissioning Nuclear Power
Plant is presented here through the results of an environmental monitoring
survey carried out in the area surrounding the Garigliano Power Plant. The
levels of radioactivity in soil, water, air and other environmental matrices
are shown, in which {\alpha}, {\beta} and {\gamma} activity and {\gamma}
equivalent dose rate are measured. Radioactivity levels of the samples from the
Garigliano area are analyzed and then compared to those from a control zone
situated more than 100 km away. Moreover, a comparison is made with a previous
survey held in 2001. The analyses and comparisons show no significant
alteration in the radiological characteristics of the area surroundings the
plant, with an overall radioactivity depending mainly from the global fallout
and natural sources
Recommended from our members
An ontological approach for recovering legacy business content
Legacy Information Systems (LIS) pose a challenge for many organizations. On one hand, LIS are viewed as aging systems needing replacement; on the other hand, years of accumulated business knowledge have made these systems mission-critical. Current approaches however are often criticized for being overtly dependent on technology and ignoring the business knowledge which resides within LIS. In this light, this paper proposes a means of capturing the business knowledge in a technology agnostic manner and transforming it in a way that reaps the benefits of clear semantic expression - this transformation is achieved via the careful use of ontology. The approach called Content Sophistication (CS) aims to provide a model of the business that more closely adheres to the semantics and relationships of objects existing in the real world. The approach is illustrated via an example taken from a case study concerning the renovation of a large financial system and the outcome of the approach results in technology agnostic models that show improvements along several dimensions
- …