11,761 research outputs found
Twisted C*-algebras associated to finitely aligned higher-rank graphs
We introduce twisted relative Cuntz-Krieger algebras associated to finitely
aligned higher-rank graphs and give a comprehensive treatment of their
fundamental structural properties. We establish versions of the usual
uniqueness theorems and the classification of gauge-invariant ideals. We show
that all twisted relative Cuntz-Krieger algebras associated to finitely aligned
higher-rank graphs are nuclear and satisfy the UCT, and that for twists that
lift to real-valued cocycles, the K-theory of a twisted relative Cuntz-Krieger
algebra is independent of the twist. In the final section, we identify a
sufficient condition for simplicity of twisted Cuntz-Krieger algebras
associated to higher-rank graphs which are not aperiodic. Our results indicate
that this question is significantly more complicated than in the untwisted
setting.Comment: Version 2: This paper has now appeared in Documenta Mathematica. This
version on arXiv exactly matches the pagination and format of the published
version. Original published version available from
http://www.math.uni-bielefeld.de/documenta/vol-19/28.htm
The Potential Economic Benefits of Integrated and Sustainable Ocean Observation Systems: The Southeast Atlantic Region
The South East Atlantic Coastal Ocean Observing System (SEACOOS) collects, manages and disseminates coastal oceanic and atmospheric observation information along the Atlantic coast of the southeastern United States. This paper estimates the benefits of SEACOOS information in eleven benefit categories. Following a methodology used in similar studies of other U.S. coastal regions, we evaluate the impacts of conservative changes in economic activity in each sector. The annual economic benefit of SEACOOS information is 's), an estimate that falls between annual benefits of 381 million for the Gulf of Mexico.
Spatial Hedonic Models for Measuring the Impact of Sea-Level Rise on Coastal Real Estate
This study uses a unique integration of geospatial and hedonic property data to estimate the impact of sea-level rise on coastal real estate in North Carolina. North Carolina’s coastal plain is one of several large terrestrial systems around the world threatened by rising sea-levels. High-resolution topographic LIDAR (Light Detection and Ranging) data are used to provide accurate inundation maps for all properties that will be at risk under six different sea-level rise scenarios. A simulation approach based on spatial hedonic models is used to provide consistent estimates of the property value losses. Results indicate that the northern part of the North Carolina coastline is comparatively more vulnerable to the effect of sea-level rise than the southern part. Low-lying and heavily developed areas in the northern coastline are especially at high risk from sea-level rise. Key Words: Climate change, coastal real estate, sea-level rise, spatial hedonic models
Measuring the Impacts of Sea Level Rise on Marine Recreational Shore Fishing in North Carolina
We develop estimates of the economic effects of sea level rise on marine recreational shore fishing in North Carolina. We estimate the relationship between angler behavior and spatial differences in beach width using the Marine Recreational Fishing Statistics Survey and geospatial data. We exploit the empirical relationship between beach width and site choice by simulating the effects of (1) sea level rise on beach width and (2) beach width on angler site choice. We find that the welfare losses are potentially substantial, ranging up to a present value of $1.26 billion over 75 years. Key Words: marine recreational fishing, travel cost method, climate change, sea level rise
An audit of dressing practice by occupational therapists in acute stroke settings in England
Introduction
Dressing independence is commonly affected after stroke, with clinical guidelines recommending that dressing practice should routinely be provided for those with dressing difficulties. The aim of this study was to update the literature on current practice in the treatment of dressing problems in stroke rehabilitation units.
Method
A questionnaire survey of occupational therapists experienced in stroke care was sent to 157 stroke units in England.
Results
Responses were received from 70 stroke units. Frequency and duration of dressing practice varied substantially between units, with respondents typically providing dressing practice for six to 10 patients per week and spending 30 to 45 minutes per treatment session. Only 17 respondents (24.3%) stated that they regularly used standardised assessments of dressing ability. The functional approach was used more widely than the remedial approach. Service priorities, working environment and limitations of time and staffing were reported to influence dressing practice.
Conclusion
There is widespread variability in dressing practice. There is a lack of use of standardised dressing assessments, and therapists’ rationale for their choice of approach is unclear
Structural transect through Silurian turbidites of the Fredericton Belt southwest of Fredericton, New Brunswick: the role of the Fredericton Fault in late Iapetus convergence
Excavations along the 23 km stretch of the Longs Creek to Fredericton section of the new Trans-Canada Highway created new exposures affording a transect through part of the Fredericton Belt west of, and including, the Fredericton Fault. This transect lies entirely in the Burtts Corner beds of the Silurian Kingsclear Group, revealing a multi-deformation history. Earliest structural elements in the turbidites include a slaty cleavage (S1) that is close to being bedding-parallel in most places. No F1 fold closures have been identified, but small enclaves of inverted bedding imply that such structures exist but are of limited scale and restricted occurrence. The most conspicuous structures are upright to overturned, open to tight F2 folds with chevron profiles, a locally well-developed axial planar slaty cleavage (S2) and a related crenulation lineation on S1 (L12). These folds have curvilinear hinge-lines that show an increase in curvilinearity toward the Fredericton Fault, coincident with a tightening of the interlimb angle. Lineations related to layer-parallel slip during F2 fold generation remain constant implying the changing geometry is a consequence of changing bulk strain rather than fold interference.
Post-F2 structures include a sparsely developed set of chevron folds with horizontal axial planes (F3) and a poorly developed axial planar slaty cleavage (S3). At least two sets of late kinks have also been noted.
Systematic variations in style and form of the F2 folds suggest a relationship with the precursor to the Fredericton Fault, implying a role for this structure in Acadian orogenic deformation starting out as a sub-horizontal detachment prior to rotation into its current vertical attitude. This low-angle dip-slip phase is related to the convergence of Avalonia* with the Miramichi terrane (the remains of the Ordovician Miramichi arc, incorporated into the Brunswick subduction complex by the mid-Silurian), and preceded the behaviour of the Fredericton Fault as an orogen-parallel strike-slip feature in later Acadian orogenesis.
* Avalonia' here refers to the composite terrane in southern New Brunswick consisting of Avalonia sensu stricto and a number of peri-Gondwanan terranes, see Barr and White (1996, 1999), or a southern terrane that is a composite of Avalonia and Ganderia (see for instance, van Staal et al. 2002). This contribution does not present any data allowing a choice between these models.
RÉSUMÉ
Des excavations le long d'un tronçon de 23 kilomètres de la section de la nouvelle transcanadienne menant de Long Creek à Fredericton ont créé de nouveaux affleurements représentant une coupe transversale d'une partie de la ceinture de Fredericton à l'ouest de la faille de Fredericton, inclusivement. Ce transect se trouve entièrement à l'intérieur des strates de Burtts Corner du groupe silurien de Kingsclear et témoigne d'un passé ayant comporté plusieurs déformations. Les éléments structuraux les plus précoces dans les turbidites comprennent une schistosité ardoiseuse (S1) presque parallèle aux strates dans la majorité des endroits. Aucune fermeture de plis F1 n'a été relevée, mais de petites enclaves de strates renversées laissent entendre que de telles structures existent mais qu'elles sont d'une échelle limitée et de fréquence réduite. Les structures les plus visibles comprennent des plis F2 ouverts à aigus, verticaux à renversés, aux profils en guirlandes, une schistosité ardoiseuse de plan axial bien développée (S2) et une linéation à crénulation apparentée sur S1 (L12). Ces plis possèdent des charnières curvilignes présentant une curvilinéarité accrue en direction de la faille de Fredericton; le phénomène correspond à un resserrement de l'angle inter-flancs. La linéation reliée au plissement parallèle aux couches pendant la production du pli F2 demeure constante, ce qui laisse supposer que la géométrie changeante est due à la déformation générale changeante plutôt qu'à l'interférence de plis.
Les structures ultérieures à F2 comprennent un ensemble peu développé de plis en guirlandes à plans axiaux horizontaux (F3) et une schistosité ardoiseuse de plan axial faiblement développée (S3). Au moins deux ensembles de flexures tardives ont également été relevés.
Les variations systématiques du style et de la forme des plis F2 laissent supposer un rapport avec la structure ayant précédé la faille de Fredericton, laissant entendre que cette structure a joué un rôle dans la déformation de l'orogenèse acadienne en commençant comme détachement subhorizontal avant sa rotation dans sa position verticale actuelle. Cette phase de rejet incliné à angle peu prononcé est apparentée à la convergence d'Avalonia* avec le terrane de Miramichi (vestiges de l'arc ordovicien de Miramichi, incorporés dans le complexe de subduction de Brunswick vers le milieu du Silurien) et a précédé le comportement de la faille de Fredericton qui est devenu un décrochement parallèle à l'orogène vers la fin de l'orogenèse acadienne.
* Le terme «Avalonia» désigne ici le terrane composite du Sud du Nouveau-Brunswick constitué d'Avalonia au sens strict et d'un certain nombre de terranes périgondwaniens (voir Barr et White, 1996, 1999), ou un terrane méridional composé d'Avalonia et de Ganderia (voir par exemple van Staal et coll., 2002). La présente contribution ne fournit aucune donnée permettant un choix entre ces modèles.
[Traduit par la rédaction.
- …