6,797 research outputs found
An infinite family of tight, not semi-fillable contact three-manifolds
We prove that an infinite family of virtually overtwisted tight contact
structures discovered by Honda on certain circle bundles over surfaces admit no
symplectic semi-fillings. The argument uses results of Mrowka, Ozsvath and Yu
on the translation-invariant solutions to the Seiberg-Witten equations on
cylinders and the non-triviality of the Kronheimer-Mrowka monopole invariants
of symplectic fillings.Comment: Published by Geometry and Topology at
http://www.maths.warwick.ac.uk/gt/GTVol7/paper30.abs.htm
The pale evidence for treatment of iron-deficiency anaemia in older people
Funding The authors have received funding to carry out a pilot RCT on management of IDA in older people from the Chief Scientist Office, Scotland.Peer reviewedPostprin
Moduli spaces of vector bundles over a Klein surface
A compact topological surface S, possibly non-orientable and with non-empty
boundary, always admits a Klein surface structure (an atlas whose transition
maps are dianalytic). Its complex cover is, by definition, a compact Riemann
surface M endowed with an anti-holomorphic involution which determines
topologically the original surface S. In this paper, we compare dianalytic
vector bundles over S and holomorphic vector bundles over M, devoting special
attention to the implications that this has for moduli varieties of semistable
vector bundles over M. We construct, starting from S, totally real, totally
geodesic, Lagrangian submanifolds of moduli varieties of semistable vector
bundles of fixed rank and degree over M. This relates the present work to the
constructions of Ho and Liu over non-orientable compact surfaces with empty
boundary (arXiv:math/0605587) .Comment: 19 pages, 1 figur
Evaluation Theory and Practice
One of the topics I was determined to discuss with my European colleagues at the Helsinki Conference was the use of theory in evaluation practice. I was thrilled to stumble upon several thought provoking discussions regarding the use of theory in evaluation. A common theme was the belief that teaching evaluation practitioners about theory was critical to a better future for the evaluation discipline. But why is theory so important? The session I addressed on this topic also involved Frans Leeuw, Evert Vedung and Gary Henry. I emerged from the session with some new (and old) insights about evaluation theory and evaluation practice. This brief article summarizes what I learnt – and what I said
An exotic smooth structure on CP^2+6CP^2-bar
We construct smooth 4-manifolds homeomorphic but not diffeomorphic to
CP^2+6CP^2-bar.Comment: Published by Geometry and Topology at
http://www.maths.warwick.ac.uk/gt/GTVol9/paper19.abs.htm
Comparison of the renal clearances of inulin and radioactive labelled hypaque as measures of the glomerular filtration rate in man
The standard method of estimating the rate of glomerular filtration
(G.F.R.) in man has been by the renal clearance of inulin since it was
demonstrated. that this plant polysaccharide is neither secreted nor reabsorbed by the renal tubules. The criteria which must be satisfied
by a substance for its renal clearance to cive a valid measure of glomerular filtration rate have been discussed in detail by Smith (1951).
Chemical methods for the determination of inulin in plasma and urine
have been rather unsatisfactory (Smith 1951) and a variety of substances
have been studied in an attempt to find a substitute for inulin. The
endogenous creatinine clearance is widely used for clinical purposes but
the creatinine/inulin clearance ratio exceeds unity in many human
subjects indicating a variable deree of tubular secretion of creatinine
(Smith 1 951 , Berlune et al 1 964) and this clearance is not a reliable
measure of glomerular filtration in man.Recently a number of compounds labelled with radioisotopes have
been studied and found to have clearances similar to'that of inulin.
Allyl inulin labelled with ¹²⁵I has a clearance virtually identical to
that of inulin in the dog (Concannon et al 1964) but is not readily
available and is difficult to sterilise. Radioactive ⁵⁷Co-labelled
cyanocobalamin gives a satisfactory measure of G.F.R. if only the free
vitamin in the plasma is measured (Nelp et al 1964, Cutler and Glatte 1965).
However, even after a large loading dose of unlabelled cyanocobalamin,
plasma protein binding, of the labelled compound occurs and is variable
in extent, nor is it easy to determine the proportion. of the labelled vitamin which is plasma bound in vivo (Skins and Sgherzi 1964,
Donaldson and Doig unpublished observations). The most convenient
inulin substitutes so far available are .the radiographic contrast media
sodium diatrizoate ( Hypaque) and meglumin diatrizoate (Renografin)
labelled with ¹³I or ¹²⁵I. In man Hypaque appears to fulfil many of
Smith's criteria, it is not significantly bound to plasma proteins
(Lasser et al 1962) nor does it readily penetrate red blood cells
(Denneberg et al 1961), its renal excretion is complete and its extrarenal excretion negligible (Denneberg 1965). Hypac,ue and Renografin
have been shown by various authors to have clearances very similar to
the simultaneous inulin or thiosulphate clearance in man and the
literature on these compounds has been well reviewed by Denneberg (1965).
However some authors have not found the Hypaque and inulin or thiosulphate clearances to be identical (Bianchi and Zampieri 1961, Woodruff
and Malvin 1560, Stokes et al 1 ;62, Denneberg 1565 and while some comparisons were carried out during continuous infusion of inulin and
Hypaque (Burbank et al 1963), others were made on the basis of a single
injection of Hypaque (Bianchi and Zampieri 1961). The latter are difficult
to interpret physiologically; the difficulties inherent in all "single
injection" clearances have been discussed by Smith (1951) and Robson et
al (1949) .It has been variously suggested that Hypaque is neither reabsorbed
nor secreted by the renal tubules in man (Burbank et al 1963), nor in
the dog Woodruff and Malvin 1960), that it is reabsorbed in man (Bianchi and Zampieri 1961) and in dog (Stokes et al 1962) and that it is
both secreted and reabsorbed in man (Denneberg 1965).Morris et al (1965) found that the clearance of ¹³¹I Renografin
did not alter when the plasma level was raised by large doses of inactive
Renografin, suggesting that this compound is not handled by the tubules.
However they studied only two subjects in this way. Hypaque would be
expected to behave in the renal tubules in the same way as Renografin
as it is the diatrizoate ion which is estimated in both cases. However
Denneberg (1965) found that the Hypaque /inulin clearance ratio fell, on
average, after the administration of the tubular blocking agent probenecid
and concluded that Hypaque is secreted and perhaps also reabsorbed by the
renal tubules in man.Because of this confusion in the literature about tubular handling
of Hypaque in man, the studies described in this paper were carried out
in an attempt to resolve the Question of whether or not radioactive
labelled Hypaque is handled by the renal tubules and to investigate its
clearance as a measure of the rate of glomerular filtration in human
subjects
Developing Capacity for International Developmental Evaluation
At the IDEAS Global Assembly this past May in the beautiful island of Barbados we engaged in discussions about improving international development evaluation capacity. With colleagues Tarek Azzam, Matthew Galen and John LaVelle, we discussed multiple initiatives ranging for the use of webinars, knowledge management systems, e-learning applications, massive open online courses, opportunities to use social media to enhance national and international conferences, and a range of university-based capacity development efforts. In this brief article we describe some of those initiatives
Remote Ergonomic Research in Space: Spacelab Findings and a Proposal
This paper discusses ergonomics research using remotely situated video camerasin spacecraft. Two prototype studies of crewmembers working in the micro-G environments aboard the first two flights of Spacelab are described. Various aspects of crew restraint, stabilization, manipulation of controls, and mobilization were observed, operationally defined, and quantified by observing videotaped scenes of Spacelab crewmembers. In the first study, four performance behaviors were quantified to provide estimates of their frequency of occurrence and variation over the course of each of the flights. The behaviors and their mean percent of observed times were: Hand-Hold 32.2%, Foot Restraint 35.3%, Translation 9.4%, and Struggle 3.7%. Because we observed that nearly a third of a crewmember\u27s time was spent inefficiently holding on With one hand while trying to work with the other, a second study was conducted exploring the use of foot restraints and hand stabilization. During 18 episodes of single-foot restraint, for example, there were 52 instances of hand stabilization and 135 instances of stabilization attempts with the other foot. The paper concludes with some defining charactenstics of adequate foot restraints, and a proposal for extending this research model to future spacecraft studies
Dissociating attention effects from categorical perception with ERP functional microstates
The research was supported by a University of Stirling Research Impact Fellowship awarded to B.D.When faces appear in our visual environment we naturally attend to them, possibly to the detriment of other visual information. Evidence from behavioural studies suggests that faces capture attention because they are more salient than other types of visual stimuli, reflecting a category-dependent modulation of attention. By contrast, neuroimaging data has led to a domain-specific account of face perception that rules out the direct contribution of attention, suggesting a dedicated neural network for face perception. Here we sought to dissociate effects of attention from categorical perception using Event Related Potentials. Participants viewed physically matched face and butterfly images, with each category acting as a target stimulus during different blocks in an oddball paradigm. Using a data-driven approach based on functional microstates, we show that the locus of endogenous attention effects with ERPs occurs in the N1 time range. Earlier categorical effects were also found around the level of the P1, reflecting either an exogenous increase in attention towards face stimuli, or a putative face-selective measure. Both category and attention effects were dissociable from one another hinting at the role that faces may play in early capturing of attention before top-down control of attention is observed. Our data support the conclusion that certain object categories, in this experiment, faces, may capture attention before top-down voluntary control of attention is initiated.Publisher PDFPeer reviewe
Elements of person knowledge : episodic recollection helps us to identify people but not to recognize their faces
This research was supported by the Scottish Imaging Network: A Platform for Scientific Excellence (www.sinapse.ac.uk) and a Grant from the Biotechnology and Biological Sciences Research Council (BB/L023644/1).Faces automatically draw attention, allowing rapid assessments of personality and likely behaviour. How we respond to people is, however, highly dependent on whether we know who they are. According to face processing models person knowledge comes from an extended neural system that includes structures linked to episodic memory. Here we use scalp recorded brain signals to demonstrate the specific role of episodic memory processes during face processing. In two experiments we recorded Event-Related Potentials (ERPs) while participants made identify, familiar or unknown responses to famous faces. ERPs revealed neural signals previously associated with episodic recollection for identify but not familiar faces. These findings provide novel evidence suggesting that recollection is central to face processing, providing one source of person knowledge that can be used to moderate the initial impressions gleaned from the core neural system that supports face recognition.Publisher PDFPeer reviewe
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