3,522 research outputs found
Induced QCD and Hidden Local ZN Symmetry
We show that a lattice model for induced lattice QCD which was recently
proposed by Kazakov and Migdal has a gauge symmetry which, in the strong
coupling phase, results in a local confinement where only color singlets are
allowed to propagate along links and all Wilson loops for non-singlets average
to zero. We argue that, if this model is to give QCD in its continuum limit, it
must have a phase transition. We give arguments to support presence of such a
phase transition
Dual variables for the SU(2) lattice gauge theory at finite temperature
We study the three-dimensional SU(2) lattice gauge theory at finite
temperature using an observable which is dual to the Wilson line. This
observable displays a behaviour which is the reverse of that seen for the
Wilson line. It is non-zero in the confined phase and becomes zero in the
deconfined phase. At large distances, it's correlation function falls off
exponentially in the deconfined phase and remains non-zero in the confined
phase. The dual variable is non-local and has a string attached to it which
creates a Z(2) interface in the system. It's correlation function measures the
string tension between oppositely oriented Z(2) domains. The construction of
this variable can also be made in the four-dimensional theory where it measures
the surface tension between oppositely oriented Z(2) domains.Comment: 13 pages, LaTeX, 4 figures are included in the latex fil
Numerical Solution of a Complete Formulation of Flow in a Perfusion Bone-Tissue Bioreactor Using Lattice Boltzmann Equation Method
We report the key findings from numerical solutions of a model of transport
within an established perfusion bioreactor design. The model includes a
complete formulation of transport with fully coupled convection-diffusion and
scaffold cell attachment. It also includes the experimentally determined
internal (Poly-L-Lactic Acid (PLLA)) scaffold boundary, together with the
external vessel and flow-port boundaries. Our findings, obtained using parallel
lattice Boltzmann equation method, relate to (i) whole-device, steady-state
flow and species distribution and (ii) the properties of the scaffold. In
particular the results identify which elements of the problem may be addressed
by coarse grained methods such as the Darcy approximation and those which
require a more complete description. The work demonstrates that appropriate
numerical modelling will make a key contribution to the design and development
of large scale bioreactors.Comment: 9 pages, 3 figure
Oscillating epidemics in a dynamic network model: stochastic and mean-field analysis
An adaptive network model using SIS epidemic propagation with link-type-dependent link activation and deletion is considered. Bifurcation analysis of the pairwise ODE approximation and the network-based stochastic simulation is carried out, showing that three typical behaviours may occur; namely, oscillations can be observed besides disease-free or endemic steady states. The oscillatory behaviour in the stochastic simulations is studied using Fourier analysis, as well as through analysing the exact master equations of the stochastic model. By going beyond simply comparing simulation results to mean-field models, our approach yields deeper insights into the observed phenomena and help better understand and map out the limitations of mean-field models
Comparison of the estimated incidence of acute leptospirosis in the Kilimanjaro Region of Tanzania between 2007-08 and 2012-14
Background:
The sole report of annual leptospirosis incidence in continental Africa of 75–102 cases per 100,000 population is from a study performed in August 2007 through September 2008 in the Kilimanjaro Region of Tanzania. To evaluate the stability of this estimate over time, we estimated the incidence of acute leptospirosis in Kilimanjaro Region, northern Tanzania for the time period 2012–2014.
Methodology and Principal Findings:
Leptospirosis cases were identified among febrile patients at two sentinel hospitals in the Kilimanjaro Region. Leptospirosis was diagnosed by serum microscopic agglutination testing using a panel of 20 Leptospira serovars belonging to 17 separate serogroups. Serum was taken at enrolment and patients were asked to return 4–6 weeks later to provide convalescent serum. Confirmed cases required a 4-fold rise in titre and probable cases required a single titre of ≥800. Findings from a healthcare utilisation survey were used to estimate multipliers to adjust for cases not seen at sentinel hospitals. We identified 19 (1.7%) confirmed or probable cases among 1,115 patients who presented with a febrile illness. Of cases, the predominant reactive serogroups were Australis 8 (42.1%), Sejroe 3 (15.8%), Grippotyphosa 2 (10.5%), Icterohaemorrhagiae 2 (10.5%), Pyrogenes 2 (10.5%), Djasiman 1 (5.3%), Tarassovi 1 (5.3%). We estimated that the annual incidence of leptospirosis was 11–18 cases per 100,000 population. This was a significantly lower incidence than 2007–08 (p<0.001).
Conclusions:
We estimated a much lower incidence of acute leptospirosis than previously, with a notable absence of cases due to the previously predominant serogroup Mini. Our findings indicate a dynamic epidemiology of leptospirosis in this area and highlight the value of multi-year surveillance to understand leptospirosis epidemiology
Universality, vortices and confinement: modified SO(3) lattice gauge theory at non-zero temperature
We investigate the adjoint SU(2) lattice gauge theory in 3+1 dimensions with
the Wilson plaquette action modified by a Z(2) monopole suppression term. For
the zero-twist sector we report indications for the existence of a finite
temperature effect decoupled from the unphysical bulk transitions.Comment: 17 pages, 10 figures. Some figures and text added. To appear on Phys.
Rev.
One health research in Northern Tanzania – challenges and progress
East Africa has one of the world’s fastest growing human populations—many of whom are dependent on livestock—as
well as some of the world’s largest wildlife populations. Humans, livestock, and wildlife often interact closely, intimately
linking human, animal, and environmental health. The concept of One Health captures this interconnectedness, including
the social structures and beliefs driving interactions between species and their environments. East African policymakers
and researchers are recognising and encouraging One Health research, with both groups increasingly playing a leading
role in this subject area. One Health research requires interaction between scientists from different disciplines, such as the
biological and social sciences and human and veterinary medicine. Different disciplines draw on norms, methodologies,
and terminologies that have evolved within their respective institutions and that may be distinct from or in conflict with one
another. These differences impact interdisciplinary research, both around theoretical and methodological approaches and
during project operationalisation. We present experiential knowledge gained from numerous ongoing projects in northern
Tanzania, including those dealing with bacterial zoonoses associated with febrile illness, foodborne disease, and anthrax.
We use the examples to illustrate differences between and within social and biological sciences and between industrialised
and traditional societies, for example, with regard to consenting procedures or the ethical treatment of animals. We
describe challenges encountered in ethical approval processes, consenting procedures, and field and laboratory logistics
and offer suggestions for improvement. While considerable investment of time in sensitisation, communication, and collaboration
is needed to overcome interdisciplinary challenges inherent in One Health research, this can yield great
rewards in paving the way for successful implementation of One Health projects. Furthermore, continued investment in
African institutions and scientists will strengthen the role of East Africa as a world leader in One Health research
Fixed twist dynamics of SO(3) gauge theory
We perform a throughout study of 3+1 dim. SO(3) LGT for any fixed-twist
background. We concentrate in particular on the physically significant trivial
and 1-twist sectors. Introducing a Z(2) monopole chemical potential the 1st
order bulk transition is moved down in the strong coupling region and weakened
to 2nd order in the 4-dim Ising model universality class. In this extended
phase diagram we gain access to a confined phase in every fixed twist sector of
the theory. The Pisa disorder operator is employed together with the Polyakov
loop to study the confinement-deconfinement transition in each sector. Due to
the specific properties of both operators, most results can be used to gain
insight in the ergodic theory, where all twist sectors should be summed upon.
An explicit mapping of each fixed twist theory to effective positive plaquette
models with fixed twisted boundary conditions is applied to better establish
their properties in the different phases.Comment: 20 pages, 11 Figures. Minor changes in text and figures, to appear in
Eur.Phys.J.
Metalanguage in L1 English-speaking 12-year-olds: which aspects of writing do they talk about?
Traditional psycholinguistic approaches to metalinguistic awareness in L1 learners elicit responses containing metalanguage that demonstrates metalinguistic awareness
of pre-determined aspects of language knowledge. This paper, which takes a more ethnographic approach, demonstrates how pupils are able to engage their own focus of metalanguage when reflecting on their everyday learning activities involving written language. What is equally significant is what their metalanguage choices reveal about
their understanding and application of written language concepts
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