296 research outputs found
Discrete Model of Ideological Struggle Accounting for Migration
A discrete in time model of ideological competition is formulated taking into
account population migration. The model is based on interactions between global
populations of non-believers and followers of different ideologies. The complex
dynamics of the attracting manifolds is investigated.
Conversion from one ideology to another by means of (i) mass media influence
and (ii) interpersonal relations is considered. Moreover a different birth rate
is assumed for different ideologies, the rate being assumed to be positive for
the reference population, made of initially non-believers. Ideological
competition can happen in one or several regions in space. In the latter case,
migration of non-believers and adepts is allowed; this leads to an enrichment
of the ideological dynamics. Finally, the current ideological situation in the
Arab countries and China is commented upon from the point of view of the
presently developed mathematical model. The massive forced conversion by
Ottoman Turks in the Balkans is briefly discussed.Comment: 24 pages, with 5 figures and 52 refs.; prepared for a Special issue
of Advances in Complex System
Antiferromagnetic 4-d O(4) Model
We study the phase diagram of the four dimensional O(4) model with first
(beta1) and second (beta2) neighbor couplings, specially in the beta2 < 0
region, where we find a line of transitions which seems to be second order. We
also compute the critical exponents on this line at the point beta1 =0 (F4
lattice) by Finite Size Scaling techniques up to a lattice size of 24, being
these exponents different from the Mean Field ones.Comment: 26 pages LaTeX2e, 7 figures. The possibility of logarithmic
corrections has been considered, new figures and tables added. Accepted for
publication in Physical Review
Summing Divergent Perturbative Series in a Strong Coupling Limit. The Gell-Mann - Low Function of the \phi^4 Theory
An algorithm is proposed for determining asymptotics of the sum of a
perturbative series in the strong coupling limit using given values of the
expansion coefficients. Operation of the algorithm is illustrated by test
examples, method for estimating errors is developed, and an optimization
procedure is described. Application of the algorithm to the theory
gives a behavior at large for its Gell-Mann
-- Low function. The fact that the exponent is close to unity can be
interpreted as a manifestation of the logarithmic branching of the type
(with ), which is
confirmed by independent evidence. In any case, the theory is
internally consistent. The procedure of summing perturbartive series with
arbitrary values of expansion parameter is discussed.Comment: 23 pages, PD
Identification of the factors associated with outcomes in a condition management programme
<p>Background: A requirement of the Government’s Pathways to Work (PtW) agenda was to introduce a Condition Management Programme (CMP). The aim of the present study was to identify the differences between those who engaged and made progress in this telephone-based biopsychosocial intervention, in terms of their health, and those who did not and to determine the client and practitioner characteristics and programme elements associated with success in a programme aimed at improving health.</p>
<p>Methods: Data were obtained from the CMP electronic spreadsheets and clients paper-based case records. CMP
standard practice was that questionnaires were administered during the pre- and post-assessment phases over the
telephone. Each client’s record contains their socio-demographic data, their primary health condition, as well as the pre- and post-intervention scores of the health assessment tool administered. Univariate and multivariate statistical analysis was used to investigate the relationships between the database variables. Clients were included in the study if their records were available for analysis from July 2006 to December 2007.</p>
<p> Results: On average there were 112 referrals per month, totalling 2016 referrals during the evaluation period. The
majority (62.8%) of clients had a mental-health condition. Successful completion of the programme was 28.5% (575
“completers”; 144 “discharges”). Several factors, such as age, health condition, mode of contact, and practitioner
characteristics, were significant determinants of participation and completion of the programme. The results
showed that completion of the CMP was associated with a better mental-health status, by reducing the number of
clients that were either anxious, depressed or both, before undertaking the programme, from 74% to 32.5%.</p>
<p>Conclusions: Our findings showed that an individual's characteristics are associated with success in the
programme, defined as completing the intervention and demonstrating an improved health status. This study
provides some evidence that the systematic evaluation of such programmes and interventions could identify ways
in which they could be improved.</p>
The U(1)-Higgs Model: Critical Behaviour in the Confinig-Higgs region
We study numerically the critical properties of the U(1)-Higgs lattice model,
with fixed Higgs modulus, in the region of small gauge coupling where the Higgs
and Confining phases merge. We find evidence of a first order transition line
that ends in a second order point. By means of a rotation in parameter space we
introduce thermodynamic magnitudes and critical exponents in close resemblance
with simple models that show analogous critical behaviour. The measured data
allow us to fit the critical exponents finding values in agreement with the
mean field prediction. The location of the critical point and the slope of the
first order line are accurately given.Comment: 21 text pages. 12 postscript figures available on reques
Representations of sport in the revolutionary socialist press in Britain, 1988–2012
This paper considers how sport presents a dualism to those on the far left of the political spectrum. A long-standing, passionate debate has existed on the contradictory role played by sport, polarised between those who reject it as a bourgeois capitalist plague and those who argue for its reclamation and reformation. A case study is offered of a political party that has consistently used revolutionary Marxism as the basis for its activity and how this party, the largest in Britain, addresses sport in its publications. The study draws on empirical data to illustrate this debate by reporting findings from three socialist publications. When sport did feature it was often in relation to high profile sporting events with a critical tone adopted and typically focused on issues of commodification, exploitation and alienation of athletes and supporters. However, readers’ letters, printed in the same publications, revealed how this interpretation was not universally accepted, thus illustrating the contradictory nature of sport for those on the far left
Divergent Perturbation Series
Various perturbation series are factorially divergent. The behavior of their
high-order terms can be found by Lipatov's method, according to which they are
determined by the saddle-point configurations (instantons) of appropriate
functional integrals. When the Lipatov asymptotics is known and several lowest
order terms of the perturbation series are found by direct calculation of
diagrams, one can gain insight into the behavior of the remaining terms of the
series. Summing it, one can solve (in a certain approximation) various
strong-coupling problems. This approach is demonstrated by determining the
Gell-Mann - Low functions in \phi^4 theory, QED, and QCD for arbitrary coupling
constants. An overview of the mathematical theory of divergent series is
presented, and interpretation of perturbation series is discussed. Explicit
derivations of the Lipatov asymptotic forms are presented for some basic
problems in theoretical physics. A solution is proposed to the problem of
renormalon contributions, which hampered progress in this field in the late
1970s. Practical schemes for summation of perturbation series are described for
a coupling constant of order unity and in the strong-coupling limit. An
interpretation of the Borel integral is given for 'non-Borel-summable' series.
High-order corrections to the Lipatov asymptotics are discussed.Comment: Review article, 45 pages, PD
Aspects of noncommutative descriptions of planar systems in high magnetic fields
We study some aspects of recent proposals to use the noncommutative
Chern-Simons theory as an effective description of some planar condensed matter
models in strong magnetic fields, such as the Quantum Hall Effect. We present
an alternative justification for such a description, which may be extended to
other planar systems where a uniform magnetic field is present
Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer's disease
Natural Cross Chlamydial Infection between Livestock and Free-Living Bird Species
The study of cross-species pathogen transmission is essential to understanding the epizootiology and epidemiology of infectious diseases. Avian chlamydiosis is a zoonotic disease whose effects have been mainly investigated in humans, poultry and pet birds. It has been suggested that wild bird species play an important role as reservoirs for this disease. During a comparative health status survey in common (Falco tinnunculus) and lesser (Falco naumanni) kestrel populations in Spain, acute gammapathies were detected. We investigated whether gammapathies were associated with Chlamydiaceae infections. We recorded the prevalence of different Chlamydiaceae species in nestlings of both kestrel species in three different study areas. Chlamydophila psittaci serovar I (or Chlamydophila abortus), an ovine pathogen causing late-term abortions, was isolated from all the nestlings of both kestrel species in one of the three studied areas, a location with extensive ovine livestock enzootic of this atypical bacteria and where gammapathies were recorded. Serovar and genetic cluster analysis of the kestrel isolates from this area showed serovars A and C and the genetic cluster 1 and were different than those isolated from the other two areas. The serovar I in this area was also isolated from sheep abortions, sheep faeces, sheep stable dust, nest dust of both kestrel species, carrion beetles (Silphidae) and Orthoptera. This fact was not observed in other areas. In addition, we found kestrels to be infected by Chlamydia suis and Chlamydia muridarum, the first time these have been detected in birds. Our study evidences a pathogen transmission from ruminants to birds, highlighting the importance of this potential and unexplored mechanism of infection in an ecological context. On the other hand, it is reported a pathogen transmission from livestock to wildlife, revealing new and scarcely investigated anthropogenic threats for wild and endangered species
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