7,933 research outputs found
Phase Diagram of the One Dimensional model with Ferromagnetic nearest-neighbor and Antiferromagnetic next-nearest neighbor interactions
We have studied the phase diagram of the one dimensional model
with ferromagnetic nearest-neighbor and antiferromagnetic next-nearest neighbor
interactions. We have applied the quantum renormalization group (QRG) approach
to get the stable fixed points and the running of coupling constants. The
second order QRG has been implemented to get the self similar Hamiltonian. This
model shows a rich phase diagram which consists of different phases which
possess the quantum spin-fluid and dimer phases in addition to the classical
N\'{e}el and ferromagnetic ones. The border between different phases has been
shown as a projection onto two different planes in the phase space
Dynamics of O(N) Model in a Strong Magnetic Background Field as a Modified Noncommutative Field Theory
In the presence of a strong magnetic field, the effective action of a
composite scalar field in an scalar O(N) model is derived using two different
methods. First, in the framework of worldline formalism, the 1PI n-point vertex
function for the composites is determined in the limit of strong magnetic
field. Then, the n-point effective action of the composites is calculated in
the regime of lowest Landau level dominance. It is shown that in the limit of
strong magnetic field, the results coincide and an effective field theory
arises which is comparable with the conventional noncommutative field theory.
In contrast to the ordinary case, however, the UV/IR mixing is absent in this
modified noncommutative field theory.Comment: Latex file, 19 pp, no figur
Non-western contexts: the invisible half
Like many other disciplines within the broad area of social sciences (e.g., anthropology, gender studies, psychology, sociology, etc.), consumer research is also highly navigated by scholars from Western countries. This, however, does not mean, by any means, that consumer research is devoted to studying Western contexts only. As evident from the ever-increasing number of regional conferences (e.g., Asia-Pacific and Latin American conferences of the Association for Consumer Research) and non-Western students' enrolment in doctoral programs at Western universities, there are many more researchers (from non-Western countries) who are entering the field and enriching it by their colourful contributions. Yet, given the low number of publications on consumer research in non-Western contexts, it seems that our current knowledge in these societies has a long way to go to flourish. More specifically, and in the domain of consumption culture research, this gap is even further widened by the fact that the culture of consumption in such contexts is largely interpreted with reference to the 'grand narratives' of Western scholars (e.g., Foucault, Mafessoli, Bourdieu, Deleuze, Baudrillard, Nietzsche, Durkheim, Derrida, etc.). Therefore, from an ontological perspective, it seems that our existing knowledge about non-Western societies lies heavily on the 'theoretical structures' that are 'constructed' by Western philosophy as a set of ideas, beliefs, and practices (Said, 1978). As Belk (1995) reminds us, consumption culture always existed in all human societies. What makes contemporary societies different from that of our predecessors' is not the fact that consumption culture did not exist in those societies, but that consumption culture has become a prevailing feature in modern society (Slater, 1997; Lury, 1996; Fırat and Venkatesh, 1995; McCracken, 1988). Therefore, the nature and dynamics of consumption culture in each society should be studied not only against the sociocultural, historical, and economic background of a given context (Western or non-Western) but also with reference to the philosophical and epistemological viewpoints that analyse and interpret cultural practices of that society from within that culture. Addressing such issues, this paper discusses some of the key reasons for lack of theory development in the field from non-western contexts. The paper invites scholars in non-Western contexts to introduce the less articulated, and sometime hidden, body of knowledge from their own contexts into the field of marketing in general and consumer research in particular
Analytic height correlation function of rough surfaces derived from light scattering
We derive an analytic expression for the height correlation function of a
rough surface based on the inverse wave scattering method of Kirchhoff theory.
The expression directly relates the height correlation function to diffuse
scattered intensity along a linear path at fixed polar angle. We test the
solution by measuring the angular distribution of light scattered from rough
silicon surfaces, and comparing extracted height correlation functions to those
derived from atomic force microscopy (AFM). The results agree closely with AFM
over a wider range of roughness parameters than previous formulations of the
inverse scattering problem, while relying less on large-angle scatter data. Our
expression thus provides an accurate analytical equation for the height
correlation function of a wide range of surfaces based on measurements using a
simple, fast experimental procedure.Comment: 6 pages, 5 figures, 1 tabl
The potential link between corporate innovations and corporate competitiveness:Evidence from IT firms in the UK
Purpose: The purpose of this paper is to provide a thorough empirical investigation of the potential link between corporate innovations and corporate competitiveness in the context of the UK IT industry. Design/methodology/approach: This research uses a panel of 216 UK IT firms for the period from 2000 to 2016. The sample data for this study were extracted from the Worldscope, extracted from the Datastream database from Thomson Reuters. For the analysis of the data, the generalised method of moments model is applied. Findings: The results of this study provide empirical evidence that there exists a strong, positive link between corporate innovations and corporate competitiveness. Such evidence further reinforces the common view in the current literature of strategic management that because of the nature of their business, firms in the IT industry need to enhance their innovative capacities on a continual basis because of their critical role on these firmsâ success and survival. Also, it is found that when the proxies for corporate innovations are lagged by two periods, their impact on corporate competitiveness becomes relatively more significant. However, when they are further lagged, i.e. by three periods, such an impact turns out to be relatively less pronounced. Research limitations/implications: The data gathered for this paper was restricted to IT-oriented firms in the UK. Using a secondary database (Datastream), the paper considered the period of 2000-2016. Originality/value: The research makes a significant contribution to the current debate on the relationship between information technology, innovation and performance, referred to in the literature as the productivity paradox, by studying the problem in the IT industry. It supports organisations from the sector in their efforts to deal with the dynamic nature of technological innovations and of the context where they operate. Methodologically, the way the study has measured the concepts of innovation and performance and the lessons learned from their analysis has also brought value to the research
Pipeline Monitoring Architecture based on observability and controllability Analysis
Recently many techniques with different applicability have been developed for damage detection in the pipeline. The pipeline system is designed as a distributed parameter system, where the state space of the distributed parameter system has infinite dimension. This paper is dedicated to the problem of observability as well as controllability analysis in the pipeline systems. Some theorems are presented in order to test the observability and controllability of the system. Computing the rank of the controllability and observability matrix is carried out using Matlab
Modelling and Analysis of Flow Rate and Pressure Head in Pipelines
Currently, various approaches with several utilities are proposed to identify damage in the pipeline. The pipeline system is modeled in the form of a distributed parameter system, such that the state space related to the distributed parameter system contains infinite dimension. In this paper, a novel technique is proposed to analyze and model the flow in the pipeline. Important theorems are proposed for testing the observability as well as controllability of the proposed model
Creation and characterization of vortex clusters in atomic Bose-Einstein condensates
We show that a moving obstacle, in the form of an elongated paddle, can
create vortices that are dispersed, or induce clusters of like-signed vortices
in 2D Bose-Einstein condensates. We propose new statistical measures of
clustering based on Ripley's K-function which are suitable to the small size
and small number of vortices in atomic condensates, which lack the huge number
of length scales excited in larger classical and quantum turbulent fluid
systems. The evolution and decay of clustering is analyzed using these
measures. Experimentally it should prove possible to create such an obstacle by
a laser beam and a moving optical mask. The theoretical techniques we present
are accessible to experimentalists and extend the current methods available to
induce 2D quantum turbulence in Bose-Einstein condensates.Comment: 9 pages, 9 figure
Blockage Detection in Pipeline Based on the Extended Kalman Filter Observer
Currently numerous approaches with various applicability have been generated in order to detect damage in pipe networks. Pipeline faults such as leaks and partial or complete blockages usually create serious problems for engineers. The model-based leak, as well as block detection methods for the pipeline systems gets more and more attention. Among these model-based methods, the state observer and state feedback based methods are usually used. While the observability, as well as controllability, are taken to be the prerequisites for utilizing these techniques. In this work, a new technique based on the extended Kalman filter observer is proposed in order to detect and locate the blockage in the pipeline. Furthermore, the analysis of observability and controllability in the pipe networks is investigated. Important theorems are given for testing the observability as well as controllability of the pipeline system
Out-of-equilibrium phase diagram of long-range superconductors
Within the ultimate goal of classifying universality in quantum many-body
dynamics, understanding the relation between out-of-equilibrium and equilibrium
criticality is a crucial objective. Models with power-law interactions exhibit
rich well-understood critical behavior in equilibrium, but the
out-of-equilibrium picture has remained incomplete, despite recent experimental
progress. We construct the rich dynamical phase diagram of free-fermionic
chains with power-law hopping and pairing, and provide analytic and numerical
evidence showing a direct connection between nonanalyticities of the return
rate and zero crossings of the string order parameter. Our results may explain
the experimental observation of so-called \textit{accidental} dynamical
vortices, which appear for quenches within the same topological phase of the
Haldane model, as reported in [Fl\"aschner \textit{et al.}, Nature Physics
\textbf{14}, 265 (2018)]. Our work is readily applicable to modern
ultracold-atom experiments, not least because state-of-the-art quantum gas
microscopes can now reliably measure the string order parameter, which, as we
show, can serve as an indicator of dynamical criticality.Comment: 17 pages, 9 figures, accepted versio
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