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Canadian Literature, No 233 (2017): Literary History

As far as pointing is concerned, a solar telescope is merely an ordinary astronomical telescope but with enhancements for observing solar and coronal features. The paper discusses the additional coordinate systems that need to be supported, shows how to generate the required solar ephemerides (both orbital and physical), and sets out a suitable application programming interface for the telescope control system to use when making solar observations.

To observe temporal changes in retinal physiology and histology in a rat model of laser-induced retinal vein occlusion (RVO).Ophthalmoscopy, fundus photography, and fluorescein angiography (FA) were performed following laser-induced central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) immediately after laser treatment and at 3 and 6 hr and 2, 4, 7, 14, and 21 days. Retinal histology was examined at 4, 7, 14, and 21 days. Full-field electroretinogram was recorded from both eyes simultaneously at day 4.For CRVO and BRVO, reperfusion of occluded branch veins was observed 1 to 2 days after treatment. Despite complete reperfusion of branch veins, retinal edema and hemorrhages peaked on day 4, and by day 14, treated retinas appeared pale and edematous upon ophthalmoscopy. In BRVO animals, retinal hemorrhages were limited to the vein-occluded region, although edema was more widespread and, to a limited extent, involved the untreated hemi-retina. Significant GCL cell loss was observed in both CRVO and BRVO groups after day 14. Regional analysis showed that relative GCL loss was greatest in the peripheral retina in BRVO group. Electroretinography disclosed moderate to severe functional deficits in photoreceptors, bipolar, and amacrine and ganglion cells.Laser-induced RVO in rats results in targeted vascular occlusion that persisted for 1 to 2 days. Functional deficits were evident and significant GCL cell loss was seen, notably within peripheral retina of the BRVO model. This reproducible model provides a valuable tool for the study of the molecular events associated with retinal ischemia and cell death.

In mouse anococcygeus cells, simultaneous measurements of membrane currents and changes in intracellular Ca 2+ were obtained using “perforated-patch” whole-cell recordings and Fura-2 microfluorimetry. Carbachol (50 μM) and cyclopiazonic acid (10 μM) produced a biphasic inward current; a transient Ca 2+ -dependent chloride current ( I ClCa ), followed by a smaller, sustained current ( I DOC ). This response was mirrored by a biphasic increase in the intracellular Ca 2+ concentration. SKF96365 (1-{β-[3-(4-methoxyphenyl) propoxyl]-4-methoxyphenethyl}-1 H -imidazole; 10 μM) and Cd 2+ (100 μM) inhibited both I DOC and the sustained increase in intracellular Ca 2+ ; La 3+ (400 μM) inhibited neither response. The results confirm that the non-selective cation current I DOC underlies capacitative Ca 2+ influx supporting sustained contractions in this tonic smooth muscle.

Purpose: To evaluate the efficacy of macular grid photocoagulation in preserving or improving central visual acuity in eyes with macular edema due to central vein occlusion (CVO) and best-corrected visual acuity of 20/50 or poorer. Methods: Patients with angiographically documented macular edema due to CVO were entered into a multicenter randomized controlled clinical trial supported by the National Eye Institute. Eligibility was determined based on both clinical examination findings and photographic documentation evaluated at a photograph reading center. Eyes were assigned randomly to macular grid photocoagulation (77 eyes) or no treatment (78 eyes). Patients were followed every 4 months for 3 years or until the end of the study. The outcome measure was visual acuity. Results: The study population consisted of 155 eyes in 155 patients. There was no difference between treated and untreated eyes in visual acuity at any point during the follow-up period. Initial median visual acuity was 20/160 in treated eyes and 20/ 125 in control eyes. Final median visual acuity was 20/200 in treated eyes and 20/160 in control eyes. However, treatment clearly reduced angiographic evidence of macular edema. Conclusion: The results of this study do not support a recommendation for macular grid photocoagulation for the population meeting the Central Vein Occlusion Study macular edema group eligibility criteria.

The Cornell Caltech Atacama Telescope1 is a 25m aperture sub-millimeter wavelength telescope to be built in northern Chile at an altitude of 5600m. Like any modern telescope, CCAT will require a powerful and comprehensive control system; writing one from scratch is not affordable, so the CCAT TCS must be based, at least in part, on existing software. This paper describes how the search for a suitable system (or systems) was carried out, looks at the criteria used to judge the feasibility of various approaches to developing the new system, and suggests the further studies needed to validate the choices. Although the purpose of the study was to find a control system for a specific telescope with its own particular technical requirements, many of the factors considered, such as maintainability, the ability to adapt to new requirements in the future and so on, are of concern to all telescopes. Consequently, the processes used to select the system for CCAT are relevant to other projects faced with the same decision, even if the conclusions turn out to be different.

The solar submillimeter-wave telescope (SST) is the only one of its kind dedicated to solar continuous observations. Two radiometers at 0.740 mm (405 GHz), and four at 1.415 mm (212 GHz) are placed in the Cassegrain focal plane of the 1.5-m dish at El Leoncito high altitude site, San Juan, Argentina. The aperture efficiencies are close to design predictions: 20% and 35% for 2 and 4 arcminutes beam sizes at 405 and 212 GHz, respectively. The positioner absolute pointing accuracy is 10 arcseconds. Spectral coverage is complemented by ground-based mid-infrared telescopes developed for high cadence observations in the continuum 10 micron band (30 THz), using small apertures and room-temperature microbolometer cameras. Using the system, a new solar burst spectral component was discovered, exhibiting fluxes increasing for smaller wavelengths, separated from the well known microwave component. Rapid sub-second pulsations are common for all bursts. The pulsations onset times of appear to be connected to the launch times of CMEs. Active regions are brighter for shorter submillimeter-waves. Mid-IR bright regions are found closely associated with calcium plages and magnetic structures near the solar photosphere. Intense and rapid 10 micron brightening was detected on active centers in association with weak flares. These results raise challenging difficulties for interpretation.

The accuracy requirements for pointing a ground-based telescope or antenna are comparatively modest; the latest Earth orientation models used by specialists have precision goals measured in microarcseconds and are excessive for such humble applications. Abridged formulations offer an attractive alternative: easier to get right, and much quicker to compute. Moreover, the revised computational procedures that the IAU introduced in 2000 to assist high-precision studies of Earth rotation lend themselves to approximation. Together with basic models for aberration and refraction, a page of inline C code is enough to predict the observed altazimuth coordinates of a star to an accuracy of 1-2 arcseconds, which is adequate for pointing a small telescope. This can be complemented by a similarly concise formulation of the basic pointing corrections for an equatorial or altazimuth mount.

The sarcoplasmic reticulum Ca-ATPase inhibitor thapsigargin (Tg; 0.4-100 nM) produced concentration-related, strong and sustained contractions of the mouse-isolated anococcygeus muscle; these contractions were dependent on extracellular calcium but were only partially reduced (by about 50%) in the presence of verapamil (10 and 100 microM). The verapamil-resistant component of the Tg-induced contraction was relaxed by the general calcium entry blockers SKF96365 (0.4-40 microM) and cadmium (50-300 microM), and by the tyrosine kinase inhibitor genistein (10-180 microM). In single smooth muscle cells loaded with Fura-2, addition of Tg (100 nM) to calcium-free medium produced a small, transient increase in fluorescence; subsequent addition of calcium (2.5 mM) produced a larger and sustained increase which was abolished on return to calcium-free conditions, but was only partially reduced by verapamil (10 microM; by about 30%). Manganese quenching of Fura-2 was enhanced in cells treated with Tg. The verapamil-resistant calcium influx was reduced by SKF96365 (20 microM) and to a lesser extent by genistein (40 microM); cadmium (200 microM) produced an initial decrease in fluorescence followed by a marked increase. These results demonstrate that, in the mouse anococcygeus, Tg can cause sustained contractions and elevations of calcium influx in the presence of verapamil; the time-course, calcium dependence and, although to a lesser extent, pharmacology of these effects generally support the proposal that excitation-contraction coupling in this tonic smooth muscle involves sustained capacitative calcium influx.

We report a system for photographic grading of the posterior fundus features of retinopathy of prematurity and correlation of such features with potential future visual function. The severity of temporal vessel traction, retinal fold, macular ectopia, retinal detachment, retrolental mass, blood vessel attenuation, retinal pigment epithelial scarring, and cataract was assessed by review of photographs at the Fundus Photograph Reading Center, Portland, Ore, according to a scheme designed to avoid bias or knowledge of treatment status. Reliability for all features was in the fair to excellent range (kappa greater than .40), except for blood vessel attenuation (kappa = .18), which was not a factor in the final outcome determination. The grading scheme provided the basis for the 3-month conclusions of the multicenter trial of cryotherapy for retinopathy of prematurity. This system will have further application in the 12-month Cryotherapy for Retinopathy of Prematurity Study conclusions and in future long-term correlation with visual acuity as the trial patients mature.

Gillichthys urotensin II (GUII; 1.5-150 nmol kg-1) reduced blood pressure in anesthetized rats, diastolic pressure being reduced to a greater extent than systolic. The effect was slow in onset (peak at 4-5 min) and longlasting (up to 60 min), and was accompanied by a reflex tachycardia. The hypotension was not blocked by propranolol or by mepyramine. In pithed rats, GUII (150 nmol kg-1) reduced the pressor responses to sympathetic nerve stimulation, noradrenaline, and Arg-vasopressin. Somatostatin (150 nmol kg-1) had no effect on the sympathetic pressor response but reduced heart rate. It is concluded that GUII is a vasodilator in the rat, an action not shared with somatostatin.

In this paper I outline the methods of pointing and tracking that are to be used on the 10-meter telescope of the W. M. Keck Observatory. I discuss the relevant reference frames and timescales, giving recipes for achieving the required transformations, and then go on to show how various telescope pointing corrections are taken into account.