4,333 research outputs found
On Tracial Operator Representations of Quantum Decoherence Functionals
A general `quantum history theory' can be characterised by the space of
histories and by the space of decoherence functionals. In this note we consider
the situation where the space of histories is given by the lattice of
projection operators on an infinite dimensional Hilbert space . We study
operator representations for decoherence functionals on this space of
histories. We first give necessary and sufficient conditions for a decoherence
functional being representable by a trace class operator on , an
infinite dimensional analogue of the Isham-Linden-Schreckenberg representation
for finite dimensions. Since this excludes many decoherence functionals of
physical interest, we then identify the large and physically important class of
decoherence functionals which can be represented, canonically, by bounded
operators on .Comment: 14 pages, LaTeX2
Weakly compact operators and the strong* topology for a Banach space
Peer reviewedPublisher PD
A Hyperfinite Factor which is not an Injective C*-Algebra
Peer reviewedPostprin
Non-Commutative Locally Convex Measures
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Quarterly Journal of Mathematics following peer review. The version of record: José Bonet and J. D. Maitland Wright Non-Commutative Locally Convex Measures Q J Math (2011) 62 (1): 21-38 first published online June 2, 2009 doi:10.1093/qmath/hap018 is available online at: http://qjmath.oxfordjournals.org/content/62/1/21We study weakly compact operators from a C*-algebra with values in a complete locally convex space. They constitute a natural non-commutative generalization of finitely additive vector measures with values in a locally convex space. Several results of Brooks, Sato and Wright are extended to this more general setting. Building on an approach due to Sato and Wright, we obtain our theorems on non-commutative finitely additive measures with values in a locally convex space, from more general results on weakly compact operators defined on Banach spaces X whose strong dual X' is weakly sequentially complete. Weakly compact operators are also characterized by a continuity property for a certain 'Right topology' as in joint work by Peralta, Villanueva, Wright and Ylinen. © 2009. Published by Oxford University Press. All rights reserved.The research of J. B. was partially supported by MEC and FEDER Project MTM2007-62643 and by GV Project Prometeo/2008/101. The support of the University of Aberdeen and the Universidad Politecnica of Valencia is gratefully acknowledged.Bonet Solves, JA.; Wright, JDM. (2011). Non-Commutative Locally Convex Measures. Quarterly Journal of Mathematics. 62(1):21-38. https://doi.org/10.1093/qmath/hap018S213862.
On Kalmbach measurability
summary:In this note we show that, for an arbitrary orthomodular lattice , when is a faithful, finite-valued outer measure on , then the Kalmbach measurable elements of form a Boolean subalgebra of the centre of
Incidence and clinical characteristics of group A rotavirus infections among children admitted to hospital in Kilifi, Kenya
Background
Rotavirus, predominantly of group A, is a major cause of severe diarrhoea worldwide, with
the greatest burden falling on young children living in less-developed countries. Vaccines
directed against this virus have shown promise in recent trials, and are undergoing
effectiveness evaluation in sub-Saharan Africa. In this region limited childhood data are
available on the incidence and clinical characteristics of severe group A rotavirus disease.
Advocacy for vaccine intervention and interpretation of effectiveness following implementation
will benefit from accurate base-line estimates of the incidence and severity of rotavirus
paediatric admissions in relevant populations. The study objective was to accurately define the
incidence and severity of group A rotavirus disease in a resource-poor setting necessary to
make informed decisions on the need for vaccine prevention.
Methods and Findings
Between 2002 and 2004 we conducted prospective surveillance for group A rotavirus
infection at Kilifi District Hospital in coastal Kenya. Children < 13 y of age were eligible as
"cases" if admitted with diarrhoea, and "controls" if admitted without diarrhoea. We calculated
the incidence of hospital admission with group A rotavirus using data from a demographic
surveillance study of 220,000 people in Kilifi District. Of 15,347 childhood admissions 3,296
(22%) had diarrhoea, 2,039 were tested for group A rotavirus antigen and, of these, 588 (29%)
were positive. 372 (63%) rotavirus-positive cases were infants. Of 620 controls 19 (3.1%, 95%
confidence interval [CI] 1.9–4.7) were rotavirus positive. The annual incidence (per 100,000
children) of rotavirus-positive admissions was 1,431 (95% CI 1,275–1,600) in infants and 478
(437–521) in under-5-y-olds, and highest proximal to the hospital. Compared to children with
rotavirus-negative diarrhoea, rotavirus-positive cases were less likely to have coexisting
illnesses and more likely to have acidosis (46% versus 17%) and severe electrolyte imbalance
except hyponatraemia. In-hospital case fatality was 2% among rotavirus-positive and 9%
among rotavirus-negative children.
Conclusions
In Kilifi > 2% of children are admitted to hospital with group A rotavirus diarrhoea in the first
5 y of life. This translates into over 28,000 vaccine-preventable hospitalisations per year across
Kenya, and is likely to be a considerable underestimate. Group A rotavirus diarrhoea is
associated with acute life-threatening metabolic derangement in otherwise healthy children.
Although mortality is low in this clinical research setting this may not be generally true in
African hospitals lacking rapid and appropriate management
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