624 research outputs found
On quantification of weak sequential completeness
We consider several quantities related to weak sequential completeness of a
Banach space and prove some of their properties in general and in -embedded
Banach spaces, improving in particular an inequality of G. Godefroy, N. Kalton
and D. Li. We show some examples witnessing natural limits of our positive
results, in particular, we construct a separable Banach space with the
Schur property that cannot be renormed to have a certain quantitative form of
weak sequential completeness, thus providing a partial answer to a question of
G. Godefroy.Comment: 9 page
Hierarchical Consensus Formation Reduces the Influence of Opinion Bias
We study the role of hierarchical structures in a simple model of collective
consensus formation based on the bounded confidence model with continuous
individual opinions. For the particular variation of this model considered in
this paper, we assume that a bias towards an extreme opinion is introduced
whenever two individuals interact and form a common decision. As a simple proxy
for hierarchical social structures, we introduce a two-step decision making
process in which in the second step groups of like-minded individuals are
replaced by representatives once they have reached local consensus, and the
representatives in turn form a collective decision in a downstream process. We
find that the introduction of such a hierarchical decision making structure can
improve consensus formation, in the sense that the eventual collective opinion
is closer to the true average of individual opinions than without it. In
particular, we numerically study how the size of groups of like-minded
individuals being represented by delegate individuals affects the impact of the
bias on the final population-wide consensus. These results are of interest for
the design of organisational policies and the optimisation of hierarchical
structures in the context of group decision making.Comment: 12 pages, 5 figure
Gaussian Belief with dynamic data and in dynamic network
In this paper we analyse Belief Propagation over a Gaussian model in a
dynamic environment. Recently, this has been proposed as a method to average
local measurement values by a distributed protocol ("Consensus Propagation",
Moallemi & Van Roy, 2006), where the average is available for read-out at every
single node. In the case that the underlying network is constant but the values
to be averaged fluctuate ("dynamic data"), convergence and accuracy are
determined by the spectral properties of an associated Ruelle-Perron-Frobenius
operator. For Gaussian models on Erdos-Renyi graphs, numerical computation
points to a spectral gap remaining in the large-size limit, implying
exceptionally good scalability. In a model where the underlying network also
fluctuates ("dynamic network"), averaging is more effective than in the dynamic
data case. Altogether, this implies very good performance of these methods in
very large systems, and opens a new field of statistical physics of large (and
dynamic) information systems.Comment: 5 pages, 7 figure
Target-specific glioma therapy in an immunocompetent mouse model : meeting abstract
Objective: Establishment of an immunocompetent mouse model representing the typical progressive stages observed in malignant human gliomas for the in vivo evaluation of novel target-specific regimens.
Methods: Isolated clones from tumours that arose spontaneously in GFAP-v-src transgenic mice were used to develop a transplantable brain tumour model in syngeneic B6C3F1 mice. STAT3 protein was knocked down by infection of tumour cells with replication-defective lentivirus encoding STAT3-siRNA. Apoptosis is designed to be induced by soluble recombinant TRAIL + chemical Bcl-2/Bcl-xL inhibitors.
Results: Striatal implantation of 105 mouse tumour cells resulted in the robust development of microscopically (2 – 3 mm) infiltrating malignant gliomas. Immunohistochemically, the gliomas displayed the astroglial marker GFAP and the oncogenic form of STAT3 (Tyr-705-phosphorylated) which is found in many malignancies including gliomas. Phosphorylated STAT3 was particularly prominent in the nucleus but was also found at the plasma membrane of peripherally infiltrating glioma cells. To evaluate the role of STAT3 in tumour progression, we stably expressed siRNA against STAT3 in several murine glioma cell lines. The effect of STAT3 depletion on proliferation, invasion and survival will be first assessed in vitro and subsequently after transplantation in vivo. Upstream and downstream components of the STAT3 signalling pathway as well as possible non-specific side effects of STAT3-siRNA expression after lentiviral infection will be examined, too.
Conclusions: Its high rate of engraftment, its similarity to the malignant glioma of origin, and its rapid locally invasive growth should make this murine model useful in testing novel therapies for malignant gliomas
Cardiovascular collapse caused by carbon dioxide insufflation during one-lung anaesthesia for thoracoscopic dorsal sympathectomy
Publisher's copy made available with the permission of the publisherCarbon dioxide insufflation into the pleural space during one-lung anaesthesia for thoracoscopic surgery is used in some centres to improve surgical access, even though this practice has been associated with well-described cardiovascular compromise. The present report is of a 35-year-old woman undergoing thoracoscopic left dorsal sympathectomy for hyperhidrosis. During one-lung anaesthesia the insufflation of carbon dioxide into the non-ventilated hemithorax for approximately 60 seconds, using a pressure-limited gas inflow, was accompanied by profound bradycardia and hypotension that resolved promptly with the release of the gas. Possible mechanisms for the cardiovascular collapse are discussed, and the role of carbon dioxide insufflation as a means of expediting lung collapse for procedures performed using single-lung ventilation is questioned.RJD Harris, G Benveniste, J Pfitznerhttp://www.aaic.net.au/Article.asp?D=200119
Betweenness Preference: Quantifying Correlations in the Topological Dynamics of Temporal Networks
We study correlations in temporal networks and introduce the notion of
betweenness preference. It allows to quantify to what extent paths, existing in
time-aggregated representations of temporal networks, are actually realizable
based on the sequence of interactions. We show that betweenness preference is
present in empirical temporal network data and that it influences the length of
shortest time-respecting paths. Using four different data sets, we further
argue that neglecting betweenness preference leads to wrong conclusions about
dynamical processes on temporal networks.Comment: 10 pages, 4 figure
Shear viscosity of the A_1-phase of superfluid 3He
The scattering processes between the quasiparticles in spin- up superfluid
with the quasiparticles in spin-down normal fluid are added to the other
relevant scattering processes in the Boltzmann collision terms. The Boltzmann
equation has been solved exactly for temperatures just below T_c_1. The shear
viscosity component of the A_1- phase drops as C_1(1-T/T_c_1)^(1/2). The
numerical factor C_1 is in fairly good agreement with the experiments
On peak phenomena for non-commutative
A non-commutative extension of Amar and Lederer's peak set result is given.
As its simple applications it is shown that any non-commutative
-algebra has unique predual,and moreover some
restriction in some of the results of Blecher and Labuschagne are removed,
making them hold in full generality.Comment: final version (the presentation of some part is revised and one
reference added
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