135 research outputs found
Enumeration of idempotents in planar diagram monoids
We classify and enumerate the idempotents in several planar diagram monoids:
namely, the Motzkin, Jones (a.k.a. Temperley-Lieb) and Kauffman monoids. The
classification is in terms of certain vertex- and edge-coloured graphs
associated to Motzkin diagrams. The enumeration is necessarily algorithmic in
nature, and is based on parameters associated to cycle components of these
graphs. We compare our algorithms to existing algorithms for enumerating
idempotents in arbitrary (regular *-) semigroups, and give several tables of
calculated values.Comment: Majorly revised (new title, new abstract, one additional author), 24
pages, 6 figures, 8 tables, 5 algorithm
Tina Fuchs Interview 2016
A 2016 interview with Tina Fuchs, the Dean of Students at Western Oregon University. In her interview, she discusses her career and the changes in student diversity and sustainability that she has witnessed over her 27 years at as an administrator at Western Oregon University
Are routinely collected NHS administrative records suitable for endpoint identification in clinical trials? Evidence from the West of Scotland coronary prevention study
Background: Routinely collected electronic patient records are already widely used in epidemiological research. In this work we investigated the potential for using them to identify endpoints in clinical trials.<p></p>
Methods: The events recorded in the West of Scotland Coronary Prevention Study (WOSCOPS), a large clinical trial of pravastatin in middle-aged hypercholesterolaemic men in the 1990s, were compared with those in the record-linked deaths and hospitalisations records routinely collected in Scotland.<p></p>
Results: We matched 99% of fatal study events by date. We showed excellent matching (97%) of the causes of fatal
endpoint events and good matching (.80% for first events) of the causes of nonfatal endpoint events with a slightly lower
rate of mismatching of record linkage than study events (19% of first study myocardial infarctions (MI) and 4% of first record linkage MIs not matched as MI). We also investigated the matching of non-endpoint events and showed a good level of matching, with .78% of first stroke/TIA events being matched as stroke/TIA. The primary reasons for mismatches were record linkage data recording readmissions for procedures or previous events, differences between the diagnoses in the routinely collected data and the conclusions of the clinical trial expert adjudication committee, events occurring outside Scotland and therefore being missed by record linkage data, miscoding of cardiac events in hospitalisations data as âunspecified chest painâ, some general miscoding in the record linkage data and some record linkage errors.<p></p>
Conclusions: We conclude that routinely collected data could be used for recording cardiovascular endpoints in clinical
trials and would give very similar results to rigorously collected clinical trial data, in countries with unified health systems such as Scotland. The endpoint types would need to be carefully thought through and an expert endpoint adjudication committee should be involved.<p></p>
3D simulations of turbulent mixing in a simplified slab-divertor geometry
Three-dimensional simulations of plasma turbulence have been run using the STORM module of BOUTâŻâŻ+âŻ+âŻin a simple slab geometry aimed at representing a single, isolated tokamak divertor leg. Turbulence is driven primarily by the Kelvin-Helmholtz mechanism due to the sheared ExB flow that forms around the separatrix due to strong radial gradients in the sheath potential which arise from strong radial gradients in the electron temperature. The turbulence forms a mixing layer around the separatrix which spreads heat and particles into the private-flux region. The resulting spread of the electron heat flux is within the experimental range measured on MAST. An effective thermal transport coefficient which is approximately 10% of the Bohm value is measured from the simulations. When a transport coefficient of this magnitude is used in a diffusive axisymmetric simulation, the time-averaged radial profiles share similar features to the full turbulence simulation
Haidingerâs brushes elicited at varying degrees of polarization rapidly and easily assesses total macular pigmentation
Macular pigments (MPs), by absorbing potentially toxic short-wavelength (400â500Â nm) visible light, provide protection against photo-chemical damage thought to be relevant in the pathogenesis of age-related macular degeneration (AMD). A method of screening for low levels of MPs could be part of a prevention strategy for helping people to delay the onset of AMD. We introduce a new method for assessing MP density that takes advantage of the polarization-dependent absorption of blue light by MPs, which results in the entoptic phenomenon called Haidingerâs brushes (HB). Subjects were asked to identify the direction of rotation of HB when presented with a circular stimulus illuminated with an even intensity of polarized white light in which the electric field vector was rotating either clockwise or anti-clockwise. By reducing the degree of polarization of the stimulus light, a threshold for perceiving HB (degree of polarization threshold) was determined and correlated (r2=0.66) to macular pigment optical density assessed using dual-wavelength fundus autofluoresence. The speed and ease of measurement of degree of polarization threshold makes it well suited for large-scale screening of macular pigmentation
Role of G proteinâcoupled receptor kinases (GRKs) in β2âadrenoceptorâmediated glucose uptake
Truncation of the Câterminal tail of the β2âAR, transfection of βARKct or overâexpression of a kinaseâdead GRK mutant reduces isoprenalineâstimulated glucose uptake, indicating that GRK is important for this response. We explored whether phosphorylation of the β2âAR by GRK2 has a role in glucose uptake or if this response is related to the role of GRK2 as a scaffolding protein. CHOâGLUT4myc cells expressing wildâtype and mutant β2âARs were generated and receptor affinity for [3H]âCGP12177A and density of binding sites determined together with the affinity of isoprenaline and BRL37344. Following receptor activation by β2âAR agonists, cAMP accumulation, GLUT4 translocation, [3H]â2âdeoxyglucose uptake, and β2âAR internalization were measured. Bioluminescence resonance energy transfer was used to investigate interactions between β2âAR and βâarrestin2 or between β2âAR and GRK2. Glucose uptake after siRNA knockdown or GRK inhibitors was measured in response to β2âAR agonists. BRL37344 was a poor partial agonist for cAMP generation but displayed similar potency and efficacy to isoprenaline for glucose uptake and GLUT4 translocation. These responses to β2âAR agonists occurred in CHOâGLUT4myc cells expressing β2âARs lacking GRK or GRK/PKA phosphorylation sites as well as in cells expressing the wildâtype β2âAR. However, β2âARs lacking phosphorylation sites failed to recruit βâarrestin2 and did not internalize. GRK2 knockâdown or GRK2 inhibitors decreased isoprenalineâstimulated glucose uptake in rat L6 skeletal muscle cells. Thus, GRK phosphorylation of the β2âAR is not associated with isoprenalineâ or BRL37344âstimulated glucose uptake. However, GRKs acting as scaffold proteins are important for glucose uptake as GRK2 knockâdown or GRK2 inhibition reduces isoprenalineâstimulated glucose uptake
A unique recipe for glass beads at Iron Age Sardis
In large parts of the Mediterranean recipes for the earliest man-made glass changed from melting mixtures of crushed quartz pebbles and halophytic plant ashes in the Late Bronze Age to the use of quartz sands and mineral soda during the Early Iron Age. Not much is known about this transition and the experimental materials which would inevitably have been connected to such technological change. In this paper we present a unique snapshot of developments in glass technology in Anatolia during the Middle Iron Age, when glass is still a relatively rare commodity. The present work focusses on black glass beads decorated with yellow trails from eighth to seventh century BCE Sardis, glass beads that are very rare for this period, and on this site. A full elemental analysis of the beads was made, and Sr, Pb and B isotope ratios were determined. This study reveals the use of a combination of a previously unknown source of silica and of mineral soda, giving rise to elevated (granite-like) Sr isotope signatures, as well as high alumina and B concentrations. The yellow trails of glass on the beads consist of lead-tin yellow type II, lead stannate, showing the earliest occurrence of this type of opacifier/colourant so far, predating any other findings by at least four centuries. The production of these glass beads may be local to Sardis and experimental in nature. It is therefore suggested that Sardis may have played its role in the technological development of the glass craft during the Iron Age
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