795 research outputs found
Langevin Trajectories between Fixed Concentrations
We consider the trajectories of particles diffusing between two infinite
baths of fixed concentrations connected by a channel, e.g. a protein channel of
a biological membrane. The steady state influx and efflux of Langevin
trajectories at the boundaries of a finite volume containing the channel and
parts of the two baths is replicated by termination of outgoing trajectories
and injection according to a residual phase space density. We present a
simulation scheme that maintains averaged fixed concentrations without creating
spurious boundary layers, consistent with the assumed physics
The biological effect of cyanoacrylate-combined calcium phosphate in rabbit calvarial defects
PURPOSE: The purpose of this study was to determine the biological effects of cyanoacrylate-combined calcium phosphate (CCP), in particular its potential to act as a physical barrier - functioning like a membrane - in rabbit calvarial defects.
METHODS: In each animal, four circular calvarial defects with a diameter of 8 mm were prepared and then filled with either nothing (control group) or one of three different experimental materials. In the experimental conditions, they were filled with CCP alone (CCP group), filled with biphasic calcium phosphate (BCP) and then covered with an absorbable collagen sponge (ACS; BCP/ACS group), or filled with BCP and then covered by CCP (BCP/CCP group).
RESULTS: After 4 and 8 weeks of healing, new bone formation appeared to be lower in the CCP group than in the control group, but the difference was not statistically significant. In both the CCP and BCP/CCP groups, inflammatory cells could be seen after 4 and 8 weeks of healing.
CONCLUSIONS: Within the limits of this study, CCP exhibited limited osteoconductivity in rabbit calvarial defects and was histologically associated with the presence of inflammatory cells. However, CCP demonstrated its ability to stabilize graft particles and its potential as an effective defect filler in bone augmentation, if the biocompatibility and osteoconductivity of CCP were improved.ope
BRS "Symmetry", prehistory and history
Prehistory - Starting from 't Hooft's (1971) we have a short look at Taylor's
and Slavnov's works (1971-72) and at the lectures given by Rouet and Stora in
Lausanne-1973 which determine the transition from pre-history to history.
History - We give a brief account of the main analyses and results of the BRS
collaboration concerning the renormalized gauge theories, in particular the
method of the regularization independent, algebraic renormalization, the
algebraic proof of S-matrix unitarity and that of gauge choice independence of
the renormalized physics. We conclude this report with a suggestion to the
crucial question: what could remain of BRS invariance beyond perturbation
theory.Comment: Talk given at: A Special day in honour of Raymond Stora, Annecy, July
8, 201
The impact of culture and sociological and psychological issues on Muslim patients with breast cancer in Pakistan
This is a non-final version of an article published in final form in Cancer Nursing, 32(4), 2009. The final published article is available from the link below.Breast cancer is the most common form of cancer in Muslim women in Pakistan. The impact of the initial diagnosis, culture, religion, and psychosocial and psychological aspects of the disease is not well established. This qualitative study examined the experience and coping strategies used by patients with breast cancer in relation to its impact on their physical, mental health, religious, and family issues. Thirty patients with breast cancer were interviewed. Data were analyzed using thematic analysis. The patient's experience of breast cancer focused on the range of emotions felt throughout the illness trajectory, the importance of religion and family support on coping strategies used to manage the adverse effects of chemotherapy, and also the financial concerns. This is the first study to examine Pakistani Muslim women's views on the lived experience of breast cancer. This article provides clarification of the voiced experiences of women with breast cancer. The data not only highlight the role of religion and family support as essential coping strategies but also emphasize the issues of isolation, aggression, and anger as common responses to chemotherapy. Unique features of this study are women's need to seek spiritual support for their illness and the overriding innate characteristic of maternal responsibility. These cultural features require further analysis and research
Renormalization of the Yang-Mills theory in the ambiguity-free gauge
The renormalization procedure for the Yang-Mills theory in the gauge free of
the Gribov ambiguity is constructed. It is shown that all the ultraviolet
infinities may be removed by renormalization of the parameters entering the
classical Lagrangian and the local redefinition of the fields.Comment: 20 pages. Some explanations extended, one reference added. Final
version published in the journa
The rolling problem: overview and challenges
In the present paper we give a historical account -ranging from classical to
modern results- of the problem of rolling two Riemannian manifolds one on the
other, with the restrictions that they cannot instantaneously slip or spin one
with respect to the other. On the way we show how this problem has profited
from the development of intrinsic Riemannian geometry, from geometric control
theory and sub-Riemannian geometry. We also mention how other areas -such as
robotics and interpolation theory- have employed the rolling model.Comment: 20 page
Immune-mediated competition in rodent malaria is most likely caused by induced changes in innate immune clearance of merozoites
Malarial infections are often genetically diverse, leading to competitive interactions between parasites. A quantitative understanding of the competition between strains is essential to understand a wide range of issues, including the evolution of virulence and drug resistance. In this study, we use dynamical-model based Bayesian inference to investigate the cause of competitive suppression of an avirulent clone of Plasmodium chabaudi (AS) by a virulent clone (AJ) in immuno-deficient and competent mice. We test whether competitive suppression is caused by clone-specific differences in one or more of the following processes: adaptive immune clearance of merozoites and parasitised red blood cells (RBCs), background loss of merozoites and parasitised RBCs, RBC age preference, RBC infection rate, burst size, and within-RBC interference. These processes were parameterised in dynamical mathematical models and fitted to experimental data. We found that just one parameter μ, the ratio of background loss rate of merozoites to invasion rate of mature RBCs, needed to be clone-specific to predict the data. Interestingly, μ was found to be the same for both clones in single-clone infections, but different between the clones in mixed infections. The size of this difference was largest in immuno-competent mice and smallest in immuno-deficient mice. This explains why competitive suppression was alleviated in immuno-deficient mice. We found that competitive suppression acts early in infection, even before the day of peak parasitaemia. These results lead us to argue that the innate immune response clearing merozoites is the most likely, but not necessarily the only, mediator of competitive interactions between virulent and avirulent clones. Moreover, in mixed infections we predict there to be an interaction between the clones and the innate immune response which induces changes in the strength of its clearance of merozoites. What this interaction is unknown, but future refinement of the model, challenged with other datasets, may lead to its discovery
On the gauge boson's properties in a candidate technicolor theory
The technicolor scenario replaces the Higgs sector of the standard model with
a strongly interacting sector. One candidate for a realization of such a sector
is two-technicolor Yang-Mills theory coupled to two degenerate flavors of
adjoint, massless techniquarks. Using lattice gauge theory the properties of
the technigluons in this scenario are investigated as a function of the
techniquark mass towards the massless limit. For that purpose the minimal
Landau gauge two-point and three-point correlation functions are determined,
including a detailed systematic error analysis. The results are, within the
relatively large systematic uncertainties, compatible with a behavior very
similar to QCD at finite techniquark mass. However, the limit of massless
techniquarks exhibits features which could be compatible with a
(quasi-)conformal behavior.Comment: 27 pages, 17 figures, 1 table; v2: persistent notational error
corrected, some minor modification
Introduction to the functional RG and applications to gauge theories
These lectures contain an introduction to modern renormalization group (RG)
methods as well as functional RG approaches to gauge theories. In the first
lecture, the functional renormalization group is introduced with a focus on the
flow equation for the effective average action. The second lecture is devoted
to a discussion of flow equations and symmetries in general, and flow equations
and gauge symmetries in particular. The third lecture deals with the flow
equation in the background formalism which is particularly convenient for
analytical computations of truncated flows. The fourth lecture concentrates on
the transition from microscopic to macroscopic degrees of freedom; even though
this is discussed here in the language and the context of QCD, the developed
formalism is much more general and will be useful also for other systems.Comment: 60 pages, 14 figures, Lectures held at the 2006 ECT* School
"Renormalization Group and Effective Field Theory Approaches to Many-Body
Systems", Trento, Ital
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