36 research outputs found
Tarski monoids: Matui's spatial realization theorem
We introduce a class of inverse monoids, called Tarski monoids, that can be
regarded as non-commutative generalizations of the unique countable, atomless
Boolean algebra. These inverse monoids are related to a class of etale
topological groupoids under a non-commutative generalization of classical Stone
duality and, significantly, they arise naturally in the theory of dynamical
systems as developed by Matui. We are thereby able to reinterpret a theorem of
Matui on a class of \'etale groupoids as an equivalent theorem about a class of
Tarski monoids: two simple Tarski monoids are isomorphic if and only if their
groups of units are isomorphic. The inverse monoids in question may also be
viewed as countably infinite generalizations of finite symmetric inverse
monoids. Their groups of units therefore generalize the finite symmetric groups
and include amongst their number the classical Thompson groups.Comment: arXiv admin note: text overlap with arXiv:1407.147
\'Etale groupoids and Steinberg algebras, a concise introduction
We give a concise introduction to (discrete) algebras arising from \'etale
groupoids, (aka Steinberg algebras) and describe their close relationship with
groupoid C*-algebras. Their connection to partial group rings via inverse
semigroups also explored
Identification of Vehicular Axle Weights with a Bridge Weigh-in-Motion System Considering Transverse Distribution of Wheel Loads
Tiling groupoids and Bratteli diagrams
Let T be an aperiodic and repetitive tiling of R^d with finite local
complexity. Let O be its tiling space with canonical transversal X. The tiling
equivalence relation R_X is the set of pairs of tilings in X which are
translates of each others, with a certain (etale) topology. In this paper R_X
is reconstructed as a generalized "tail equivalence" on a Bratteli diagram,
with its standard AF-relation as a subequivalence relation.
Using a generalization of the Anderson-Putnam complex, O is identified with
the inverse limit of a sequence of finite CW-complexes. A Bratteli diagram B is
built from this sequence, and its set of infinite paths dB is homeomorphic to
X. The diagram B is endowed with a horizontal structure: additional edges that
encode the adjacencies of patches in T. This allows to define an etale
equivalence relation R_B on dB which is homeomorphic to R_X, and contains the
AF-relation of "tail equivalence".Comment: 34 pages, 4 figure
The use of electronic alerts in primary care computer systems to identify the excessive prescription of short-acting beta2-agonists for people with asthma: a systematic review.
Computers are increasingly used to improve prescribing decisions in the management of long-term conditions however the effects on asthma prescribing remain unclear. We aimed to synthesise the evidence for the use of computerised alerts that identify excessive prescribing of short-acting beta2-agonists (SABAs) to improve asthma management for people with asthma. MEDLINE, CINAHL, Embase, Cochrane and Scopus databases (1990-2016) were searched for randomised controlled trials using electronic alerts to identify excessive prescribing of SABAs for people with asthma in primary care. Inclusion eligibility, quality appraisal (Cochrane risk of bias tool) and data extraction were performed by two independent reviewers. Findings were synthesised narratively. A total of 2035 articles were screened and four trials were eligible. Three studies had low risk of bias: one reported a positive effect on our primary outcome of interest, excessive SABA prescribing; another reported positive effects on the ratio of inhaled corticosteroid (ICS)-SABA prescribing, and asthma control; a third reported no effect on outcomes of interest. One study at high risk of bias reported a reduction in exacerbations and primary care consultations. There is some evidence that electronic alerts reduce excessive prescribing of SABAs, when delivered as part of a multicomponent intervention in an integrated health care system. However due to the variation in health care systems, intervention design and outcomes measured, further research is required to establish optimal design of alerting and intervening systems.The authors wish to thank Asthma UK and Queen Mary University London for funding
this work as part of a PhD studentship carried out by S.M. A.D.S. is funded by a NIHR
Academic Clinical Lectureship. A.B. is a National Institute for Health Research (NIHR)
Senior Investigator and additionally was supported by the NIHR Respiratory Disease
Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust
and Imperial College London. M.T. is supported by the NIHR Collaboration for
Leadership in Applied Health Research and Care (CLAHRC) Wessex, NIHR School of
Primary Care Research and NIHR Southampton Biomedical Research Centre. C.G. is
supported by the NIHR CLAHRC North Thames at Bart’s Health NHS Trust. The views
expressed are those of the author(s) and not necessarily those of the NHS, the NIHR
or the Department of Health. This work is funded by Asthma UK and Queen Mary
University of London
Prevalence of depression in Parkinson's disease: effects of disease stage, motor subtype and gender
Contains fulltext :
96218.pdf (publisher's version ) (Closed access)Depression is one of the most common non-motor symptoms of Parkinson's disease (PD) with a large negative impact on the quality of life. Factors such as disease stage, subtype of PD and gender might play an important role in the prevalence of depression, but a large study investigating all these factors in a within-subject design is lacking. Therefore we studied a homogeneous group of 256 Dutch PD patients (60% men, mean age=65.12 (+/-9.6) years). In total, 36.3% of the subjects had a BDI-score indicative for a minor depression, while 12.9% had a major depression. Notably, only 8.6% of the minor depressed patients and 30.3% of the major depressed patients were taking antidepressants. A higher prevalence of depression was observed in the later stages of the disease. However, this finding was absent in a smaller subsample after correction for cognitive impairment. Our data did not show a difference in the prevalence of depression between the motor subtypes and showed a trend towards higher prevalence of depression in the tremor dominant group. There was no significant difference in the prevalence of depression between men and women. We will discuss the relevance of these results in relation to the findings of other studies
Étale groupoids and Steinberg Algebras : a concise introduction
In the last couple of years, étale groupoids have become a focal point in several areas of mathematics. The convolution algebras arising from étale groupoids, considered both in analytical setting [50] and algebraic setting [23, 54], include many deep and important examples such as Cuntz algebras [27] and Leavitt algebras [40] and allowsystematic treatment of them. Partial actions and partial symmetries can also be realised as étale groupoids (via inverse semigroups), allowing us to relate convolution algebras to partial crossed products [28, 30]. Realising that the invariants long studied in topological dynamics can be modelled on étale groupoids (such as homology, full groups and orbit equivalence [41]) and that these are directly related to invariants long studied in analysis and algebra (such as K-theory) allows interaction between areas; we can use techniques developed in algebra in analysis and vice versa. The étale groupoid is the Rosetta stone