Fast Retinal Vessel Detection and Measurement Using Wavelets and Edge Location Refinement

The relationship between changes in retinal vessel morphology and the onset and progression of diseases such as diabetes, hypertension and retinopathy of prematurity (ROP) has been the subject of several large scale clinical studies. However, the difficulty of quantifying changes in retinal vessels in a sufficiently fast, accurate and repeatable manner has restricted the application of the insights gleaned from these studies to clinical practice. This paper presents a novel algorithm for the efficient detection and measurement of retinal vessels, which is general enough that it can be applied to both low and high resolution fundus photographs and fluorescein angiograms upon the adjustment of only a few intuitive parameters. Firstly, we describe the simple vessel segmentation strategy, formulated in the language of wavelets, that is used for fast vessel detection. When validated using a publicly available database of retinal images, this segmentation achieves a true positive rate of 70.27%, false positive rate of 2.83%, and accuracy score of 0.9371. Vessel edges are then more precisely localised using image profiles computed perpendicularly across a spline fit of each detected vessel centreline, so that both local and global changes in vessel diameter can be readily quantified. Using a second image database, we show that the diameters output by our algorithm display good agreement with the manual measurements made by three independent observers. We conclude that the improved speed and generality offered by our algorithm are achieved without sacrificing accuracy. The algorithm is implemented in MATLAB along with a graphical user interface, and we have made the source code freely available. 

SUPERNOVA 1996cr: SN 1987A's WILD COUSIN?

We report on new VLT optical spectroscopic and multiwavelength archival observations of SN 1996cr, a previously identified ultraluminous X-ray source known as Circinus galaxy X-2. Our optical spectrum confirms SN 1996cr as a bona fide Type IIn supernova, while archival imaging from the Anglo-Australian Telescope archive isolates the explosion date to between 1995 February 28 and 1996 March 16. SN 1996cr is one of the closest SNe (approximate to 3.8 Mpc) in the last several decades, and in terms of flux ranks among the brightest radio and X-ray SNe ever detected. The wealth of optical, X-ray, and radio observations that exist for this source provide relatively detailed constraints on its postexplosion expansion and progenitor history, including a preliminary angular size constraint from VLBI. Archival X-ray and radio data imply that the progenitor of SN 1996cr evacuated a large cavity just prior to exploding: the blast wave likely spent similar to 1-2 yr in relatively uninhibited expansion before eventually striking the dense circumstellar material which surrounds SN 1996cr. The X-ray and radio emission, which trace the progenitor mass-loss rate, have respectively risen by a factor of greater than or similar to 2 and remained roughly constant over the past 7 years. This behavior is reminiscent of the late rise of SN 1987A, but 1000 times more luminous and much more rapid to onset. SN 1996cr may likewise provide us with a younger example of SN 1978K and SN 1979C, both of which exhibit flat X-ray evolution at late times. Complex oxygen line emission hints at a possible concentric shell or ringlike structure. The discovery of SN 1996cr suggests that a substantial fraction of the closest SNe observed in the last several decades have occurred in wind-blown bubbles, and argues for the phenomena being widespread.

Agency and Appetite for religious Song: Vexilla regis prodeunt and its first thousand years

When James Joyce made two of his characters in ‘‘Portrait of an Artist as a Young Man’’ refer approvingly to ‘‘Vexilla regis prodeunt’’ he was following in the footsteps of a long line of the Latin text’s admirers. Since Anglo-Saxon times English audiences had clearly appreciated the sonorous majesty of this processional hymn, largely because of the solemnity and craft with which it celebrated the nature of Christ’s martial triumph and sacrifice. This article offers a snapshot of different kinds of English appetite for Venantius Fortunatus’ famous religious song for the first thousand years of its existence, from the Anglo-Saxon period through to the mid sixteenth century.

Effect of glucose on endothelin-1-induced calcium transients in cultured bovine retinal pericytes

Published work has shown that endothelin-l-induced contractility of bovine retinal pericytes is reduced after culture in high concentrations of glucose. The purpose of the present study was to establish the profile of endothelin-l-induced calcium transients in pericytes and to identify changes occurring after culture in high concentrations of glucose. Glucose had no effect on basal levels of cytosolic calcium or on endothelin-l-induced calcium release from intracellular stores. However, influx of calcium from the extracellular medium after endothelin-l stimulation was reduced in pericytes that had been cultured in 25 mM D-glucose. L-type Ca2+ currents were identified by patch clamping. The L-type Ca2+ channel agonist, (-)-Bay K8644, caused less influx of calcium from the extracellular medium in pericytes that had been cultured in 25 mM D-glucose than in those cultured with 5 mM D-glucose. However, 3-O-methylglucose, a nonmetabolizable analogue of glucose which can cause glycation, had similar effects to those of high concentrations of glucose. The results suggest that reduced function of the L-type Ca2+ channel that occurs in bovine retinal pericytes after culture in high concentrations of D-glucose is probably due to glycation of a channel protein.

Acculturation and religion in schools: the views of young people from minority belief backgrounds

This paper aims to explore the relationship between religious identity, acculturation strategies and perceptions of acculturation orientation in the school context amongst young people from minority
belief backgrounds. Based on a qualitative study including interviews with 26 young people from religious minority belief backgrounds in Northern Ireland, it is argued that acculturation theory provides a useful lens for understanding how young people from religious minority belief backgrounds navigate majority religious school contexts. Using a qualitative approach to explore acculturation theory enables an in-depth understanding of the inter-relationship between minority belief youth’s acculturation strategies and their respective school contexts. Similar to previous research, integrationist attitudes generally prevailed amongst minority belief young people in this study. The findings highlight how young people negotiate their religious identities in a complex web of inter-relationships between their minority religious belief community and the mainstream school culture as represented through peer and staff attitudes, school ethos and practices and religious education. Young people demonstrated differentiated understandings of acculturation orientations within the school context, which they evaluated on the basis of complex perceptions of educational policy, interpersonal relationships and individuals’ motivations. Findings are discussed in view of acculturation tensions, which arose particularly in relation to the religious education curriculum and their implications for opt-out provision as stipulated by human rights law.

Diabetes downregulates large-conductance Ca2+-activated potassium beta 1 channel subunit in retinal arteriolar smooth muscle

Retinal vasoconstriction and reduced retinal blood flow precede the onset of diabetic retinopathy. The pathophysiological mechanisms that underlie increased retinal arteriolar tone during diabetes remain unclear. Normally, local Ca(2+) release events (Ca(2+)-sparks), trigger the activation of large-conductance Ca(2+)-activated K(+)(BK)-channels which hyperpolarize and relax vascular smooth muscle cells, thereby causing vasodilatation. In the present study, we examined BK channel function in retinal vascular smooth muscle cells from streptozotocin-induced diabetic rats. The BK channel inhibitor, Penitrem A, constricted nondiabetic retinal arterioles (pressurized to 70mmHg) by 28%. The BK current evoked by caffeine was dramatically reduced in retinal arterioles from diabetic animals even though caffeine-evoked [Ca(2+)](i) release was unaffected. Spontaneous BK currents were smaller in diabetic cells, but the amplitude of Ca(2+)-sparks was larger. The amplitudes of BK currents elicited by depolarizing voltage steps were similar in control and diabetic arterioles and mRNA expression of the pore-forming BKalpha subunit was unchanged. The Ca(2+)-sensitivity of single BK channels from diabetic retinal vascular smooth muscle cells was markedly reduced. The BKbeta1 subunit confers Ca(2+)-sensitivity to BK channel complexes and both transcript and protein levels for BKbeta1 were appreciably lower in diabetic retinal arterioles. The mean open times and the sensitivity of BK channels to tamoxifen were decreased in diabetic cells, consistent with a downregulation of BKbeta1 subunits. The potency of blockade by Pen A was lower for BK channels from diabetic animals. Thus, changes in the molecular composition of BK channels could account for retinal hypoperfusion in early diabetes, an idea having wider implications for the pathogenesis of diabetic hypertension.

Vegetarian diets, low-meat diets and health:a review

OBJECTIVE: To review the epidemiological evidence for vegetarian diets, low-meat dietary patterns and their association with health status in adults. DESIGN: Published literature review focusing primarily on prospective studies and meta-analyses examining the association between vegetarian diets and health outcomes. RESULTS: Both vegetarian diets and prudent diets allowing small amounts of red meat are associated with reduced risk of diseases, particularly CHD and type 2 diabetes. There is limited evidence of an association between vegetarian diets and cancer prevention. Evidence linking red meat intake, particularly processed meat, and increased risk of CHD, cancer and type 2 diabetes is convincing and provides indirect support for consumption of a plant-based diet. CONCLUSIONS: The health benefits of vegetarian diets are not unique. Prudent plant-based dietary patterns which also allow small intakes of red meat, fish and dairy products have demonstrated significant improvements in health status as well. At this time an optimal dietary intake for health status is unknown. Plant-based diets contain a host of food and nutrients known to have independent health benefits. While vegetarian diets have not shown any adverse effects on health, restrictive and monotonous vegetarian diets may result in nutrient deficiencies with deleterious effects on health. For this reason, appropriate advice is important to ensure a vegetarian diet is nutritionally adequate especially for vulnerable groups.

Improvising (Il)legality: Justice and the Irish Diaspora, NYC, 1930-32

The Seabury Commission, 1930-32, probed allegations of corruption made against, amongst others, the Irish-American Mayor of New York City, James J. ‘Jimmy’ Walker, and the Irish-dominated Tammany Hall, the Democratic political machine that had supported Walker. Taking the Seabury inquiry as its focus, this article explores these allegations from the perspective of Critical Studies in Improvisation (C.S.I.) fused with postcolonial critique. Improvisation, in accordance with C.S.I. principles, is not a lawless or extempore event; it is, instead, lawful, or full of law. The laws of improvisation may appear impenetrable to those unfamiliar with the practice. However, when read through a hibernocentric postcolonial perspective, their meaning and form become more understandable. As will be argued in this article, diasporic communities are inherently improvisatory; that is, they utilise improvisational techniques to help adapt and respond to new situations and social contexts. To be queried is whether the law and politics practiced by Tammany and Walker, taken together, constituted a markedly Irish approach to justice, one that entailed not scripted or planned illegality, as was alleged by Judge Seabury, but improvisations on Anglo-Protestant law as a response to the displacement of and discrimination against the Irish Diaspora in early twentieth century America.