bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does optic disc topography vary during office hours?
Authors: Gunvant P. , Broadway D. , Watkins R. 
Published: March 2003

Purpose:  To investigate whether there is variation in optic disc topography as measured by the Heidelberg Retina Tomograph (HRT), in normals during office hours.Methods:  Thirty normal subjects (22 females and 8 males, median age 28 years, range 18–58) underwent Goldmann tonometry and optic disc analysis with the HRT. Three HRT readings were taken at each visit and a mean topographic image (MTI) produced. Measurements were performed in the morning (07.00–09.00 hours) and were repeated later the same day (17.00–19.00 hours). We studied the following topographic parameters: cup‐to‐disc area ratio (CDR), rim volume (RV), cup shape measure (CSM), and retinal nerve fibre layer thickness (RNFLT) in relation to time of day and the change in intraocular pressure (IOP).Results:  The median changes in the topographic parameters were as follows (a negative value indicates a larger value in the evening): CDR (median 0.001, 95% CI: −0.007 to 0.007), RV (median 0.003, 95% CI: −0.021 to 0.016), CSM (median: −0.003, 95% CI: −0.015 to 0.007) and RNFLT (median 0.006, 95% CI: −0.010 to 0.009). No parameter exhibited statistically significant change. The median morning IOP was 14 mmHg (95% CI: 13–16 mmHg) and was not significantly different (Wilcoxon's W = 234; p = 0.27) to evening IOP when it was 13 mmHg (95% CI: 12–15 mmHg). The median difference in IOP was 1 mmHg higher in the morning than the evening (range 6 mmHg higher in the morning to 4 mmHg higher in the evening). The parameter changes between the morning MTI and the evening MTI were independent of IOP changes using Kendall's tau statistic for each parameter.Conclusions:  There was no variation in HRT parameters when measured during office hours. Small intraindividual changes in IOP do not significantly affect optic disc topography.
Effects of ethnic origin on pulsatile ocular blood flow
Authors: Gunvant P. , Broadway D. C. , Watkins R. J. 
Published: March 2003

Purpose:  To study the effect of ethnicity on pulsatile ocular blood flow (POBF).Methods:  Eighty subjects from the staff and student population at Anglia Polytechnic University were examined. Forty subjects (20 males, 20 females) were Asian (originating from the Indian subcontinent) and 40 (20 males, 20 females) were white people. The subjects underwent a complete ophthalmic examination including refraction, slitlamp examination and biomicroscopic fundoscopy. Subjects with ocular pathology were excluded from the study. Subjects underwent POBF measurement on a randomly selected eye with an Ocular Blood Flow Analyzer (Paradigm Medical Industries, Salt Lake City, UT, USA). The Analyzer probe was mounted on a slitlamp and all measurements were performed by an experienced observer (PG).Results:  The median age of the Asian subjects was 22 years (males 22 years; females 22 years) and of the white people was 24 years (males 26 years; females 23 years). The racial groups were comparable for age (Mann–Whitney U = 686.5, p = 0.27), refraction (Mann–Whitney U = 735.5, p = 0.4658) and IOP (Mann–Whitney U = 856, p = 0.5899). The mean POBF values in the Caucasian and Asian groups were 1033 µL min−1 (95% CI: 940–1125 µL min−1) and 1061 µL min−1 (95% CI: 958–1165 µL min−1), respectively. The difference in POBF between the ethnic groups did not reach statistical significance (Mann–Whitney U = 0.07, p = 0.7987). Females had a higher mean POBF than males (Mann–Whitney U = 1163; p = 0.0005) but there was no interaction with race (two‐way anovaF = 1.09; p = 0.2997).Conclusions:  There was no significant difference between the mean POBF values for subjects originating from the Indian subcontinent and Caucasian subjects. The previously reported gender difference in mean POBF was confirmed. We suggest that reported differences in POBF values in different races may arise from instrumental factors.
The use of critical flicker frequency (CFF) as a potential vision test prior to cataract surgery: a pilot study
Authors: Vianya M. , Douthwaite W. A. , Elliott D. B. 
Published: March 2003

Background:  To determine whether a patient would benefit from cataract surgery, a pre‐operative evaluation of retinal visual function is required. Age‐related macular disease has been reported as the most important factor leading to poor outcome after cataract surgery. The critical flicker frequency (CFF) is a psychophysical test that measures temporal resolution properties in the visual system.Purpose:  (1) To evaluate if CFF can be used as a tool to predict visual outcome after cataract surgery. (2) To assess if lens opacities and/or retinal damage affects CFF values. (3) To assess the optimal configuration for the CFF target in relation to stimulus size.Methods:  Thirty‐two patients have been included in the pilot study. Subjects were divided into the following categories: cataract, central retinal disease, pseudophakes and cataract after pupil dilatation. CFF threshold measurements were obtained after optimal refraction and visual acuity measurement using a Bailey–Lovie logMAR chart. A staircase method was used to find the CFF threshold. For each subject, three different stimulus sizes were analysed.Results:  Critical flicker frequency measurements were unaffected by the presence of cataract (p > 0.05). Pupil dilatation gave slight higher results in patients with cataracts, although this difference was not statistically significant (anovaF = 3.6, p = 0.07). A significant difference for the three targets sizes was found (anovaF = 41.94, p < 0.05). Retinal disease produced an insignificant decrease in CFF (p > 0.05, n = 5).Conclusions:  Critical flicker frequency appears to be independent of the image degrading effects of cataract. Comparison of the means for the different conditions studied show a slight decrease in CFF measurement for retinal disease in comparison to the cataract group. However, more subjects are needed to determine the usefulness of CFF as a potential vision test.
Changes in short‐wavelength resolution acuity with age and defocus in the periphery: implications for relative ganglion cell loss
Authors: Anderson R. S. , Zlatkova M. B. , Coulter E. , Demirel S. 
Published: March 2003

Purpose:  Resolution acuity is known to be sampling limited for achromatic gratings in peripheral vision. In addition, peripheral achromatic resolution is unaffected by defocus up to 3 D. We have also shown resolution for Short Wavelength Sensitive (SWS) system isolating gratings to be sampling limited in both the fovea and periphery. This means that measurements of peripheral resolution with either stimulus can potentially be used to estimate the density of the corresponding underlying retinal ganglion cell population. We wished to examine the effect of optical defocus on detection and resolution acuity for this stimulus and also determine how peripheral resolution declined with age for both the achromatic and SWS system.Methods:  We measured detection and resolution for SWS‐isolating gratings in the fovea and at 20° eccentricity for optical defocus between 0 and 4 D. In addition we measured resolution acuity for both achromatic and SWS‐isolating gratings at 13° in four retinal locations in 50 normal subjects ranging in age from 12 to 70 years. Measurements of lens density (age‐related yellowing) were also made in subjects over 60 years of age.Results:  Detection acuity was initially higher than resolution accompanied by observations of aliasing. Detection acuity declined steadily with defocus but SWS resolution acuity showed no decline until 1 D in the fovea and 3 D at 20°. Resolution acuity was higher for achromatic gratings than SWS‐isolating gratings at all ages and neither displayed any decline in performance until around 55 years. After this both declined in a parallel fashion at a rate of 10% per decade. The individual ratio of SWS/achromatic resolution (0.25) showed no correlation with increasing lens density.Conclusions:  As resolution for both short‐wavelength and achromatic gratings is robust to optical attenuation and declines in a parallel fashion after 55 years there appears to be no selective loss of SWS‐driven ganglion cell density relative to achromatic density with age.
An Update on Exercise Therapy for Knee Osteoarthritis
Authors: Baker Kristin 
Published: March 2003

AbstractKnee osteoarthritis (OA) is the most common joint disorder in the United States. In the elderly population, symptomatic knee OA accounts for more dependency in lower‐extremity tasks than any other disease. Treatments have generally targeted pain, assuming that disability would be lessened as a direct result of improvements in pain control. However, there is evidence that pain and disability have different determinants. Exercise has the potential to mitigate many of the factors that lead to disability. In 1995, on the basis of several small, positive studies, the American College of Rheumatology recommended strength training and aerobic exercise for the treatment of knee OA. In the past several years, a number of intervention studies on exercise have been published. It is notable that all of the recent exercise studies report positive effects on pain and/or disability, although there is considerable variability in the magnitude of the effect. This variability may be due to differences in study design, exercise protocols, and study participants. Further studies are needed to better define the mechanisms responsible for the positive effects of exercise and to formulate a clear, concise exercise protocol that may have the potential to become a public health intervention for knee OA.
Exercise for Disease Prevention in the Geriatric Population
Authors: Singh Maria A. Fiatarone 
Published: March 2003

Abstract
Old age does not mitigate the importance of disease prevention as a primary therapeutic goal of healthcare practitioners. The rationale for the use of exercise as one way to achieve this goal rests upon the relationship of physical activity to a wide variety of chronic diseases, its role in risk‐factor reduction, its relationship to frailty, and its intersection with psychological health, nutritional status, and other health‐related behaviors. Evidence for the efficacy of exercise as a preventive strategy in the geriatric cohort comes from both large epidemiological studies and randomized clinical trials. The most promising are!as of benefit have to do with falls, type 2 diabetes, stroke,! coronary heart disease, osteoporosis, obesity, and depression. Primary‐prevention trials in healthy elders remain to be conducted for some disease outcomes; the same is true for vulnerable cohorts at high risk of incident disease, as there is a paucity of well‐designed clinical trials in those over the age of 75. Current knowledge suggests that various elements of the exercise prescription for disease prevention in the older adult should be individualized depending on patient profile and treatment goals. Variable emphasis on aerobic, resistive, and balance exercises is recommended, given the physiological specificity of adaptations to these modalities of activity. Concomitant behavioral strategies specific to sedentary elders and adapted to individual pragmatic needs, barriers to exercise adoption, and adherence are critical to the success of the exercise prescription in this setting.
Evaluation and Treatment of Iron Deficiency in Adults
Authors: Ross Elizabeth M. 
Published: March 2003

AbstractIron deficiency is prevalent in populations seen in primary practices. It is easily evaluated and treated, but often undiagnosed. Iron deficiency can lead not only to anemia but to decreased work capacity, abnormal neurotransmitter function, and altered immunologic and inflammatory defenses. Risk for iron deficiency is a function of iron loss, iron intake, iron absorption, and physiologic demands. Women of child‐bearing age are at especially high risk for iron deficiency due to ongoing menstrual blood losses. This article presents and describes a simple algorithm incorporating dietary considerations for evaluation and treatment of iron deficiency in primary care settings.
Model for the development of kyanite during partial convective overturn of Archean granite–greenstone terranes: the Pilbara Craton, Australia
Authors: COLLINS  , VAN KRANENDONK*  
Published: March 2003

Restricted occurrences of early, syn‐ and late‐kinematic kyanite adjacent to large domal batholiths in the Archean granite–greenstone terrane of the east Pilbara craton, Australia, are considered to result from partial convective overturn of the crust. The analogue models of Dixon & Summers (1983) and thermo‐mechanical models of Mareschal & West (1980), involving gravitionational overturn of dense greenstone crust that initially overlay sialic basement, successfully explain the geometry, dimension, kinematics and strain patterns of the batholiths and greenstone rims. Application of these models suggests that andalusite and sillimanite are the stable aluminosilicate polymorphs in domal crests and rims, where prograde clockwise P–T–t paths, with small pressure changes, should be recorded. Both aluminosilicates are predicted to overprint kyanite, which is observed locally around the east Pilbara domes. Kyanite is the predicted aluminosilicate polymorph in the deeper parts of domal rims and within sinking greenstone keels, reflecting rapid, near‐isothermal burial. The narrow zones of kyanite‐bearing schists adjacent to some batholiths in the Pilbara craton are metamorphosed, highly strained equivalents of altered felsic volcanic rocks in the low‐grade greenstone succession, dragged to mid‐crustal depths (6 kbar) during greenstone sinking. The schists rebounded as an arcuate tectonic wedge along the southern Mount Edgar batholith rim, during the later stages of doming, and were juxtaposed against regional, greenschist facies, low‐strain greenstones. Thus, kyanite was preserved: if the walls had remained at depth, it would have been overprinted by the higher‐temperature aluminosilicate polymorphs during thermal recovery.Kyanite growth in the Pilbara craton is unlikely to have resulted from ballooning of plutons, mantled gneiss doming, metamorphic core complex formation, or early crustal overthickening. The typical subvertical foliations and lineations of the tectonic wedge suggest that subvertical fabrics extended to mid‐crustal depths (c. 20 km) before rebound, providing a three‐dimensional glimpse of Archean dome‐and‐keel structures. The general occurrence of large granitoid domes in Archean granite–greenstone terranes, restriction of rare kyanite to the adjacent, high‐strain batholith margins, and its absence from the batholiths, suggest that partial convective overturn of the crust may have been a common process at this early stage of Earth history.
Constraints on the application of carbon isotope thermometry in high‐ to ultrahigh‐temperature metamorphic terranes
Authors: Satish‐Kumar M. , Wada H. , Santosh M. 
Published: March 2003

AbstractNine marble horizons from the granulite facies terrane of southern India were examined in detail for stable carbon and oxygen isotopes in calcite and carbon isotopes in graphite. The marbles in Trivandrum Block show coupled lowering of δ13C and δ18O values in calcite and heterogeneous single crystal δ13C values (− 1 to − 10‰) for graphite indicating varying carbon isotope fractionation between calcite and graphite, despite the granulite facies regional metamorphic conditions. The stable isotope patterns suggest alteration of δ13C and δ18O values in marbles by infiltration of low δ13C–δ18O‐bearing fluids, the extent of alteration being a direct function of the fluid‐rock ratio. The carbon isotope zonation preserved in graphite suggests that the graphite crystals precipitated/recrystallized in the presence of an externally derived CO2‐rich fluid, and that the infiltration had occurred under high temperature and lowfO2conditions during metamorphism. The onset of graphite precipitation resulted in a depletion of the carbon isotope values of the remaining fluid+calcite carbon reservoir, following a Rayleigh‐type distillation process within fluid‐rich pockets/pathways in marbles resulting in the observed zonation. The results suggest that calcite–graphite thermometry cannot be applied in marbles that are affected by external carbonic fluid infiltration. However, marble horizons in the Madurai Block, where the effect of fluid infiltration is not detected, record clear imprints of ultrahigh temperature metamorphism (800–1000 °C), with fractionations reaching <2‰. Zonation studies on graphite show a nominal rimward lowering δ13C on the order of 1 to 2‰. The zonation carries the imprint of fluid deficient/absent UHT metamorphism. Commonly, calculated core temperatures are  > 1000 °C and would be consistent with UHT metamorphism.
Grain‐scale melt distribution in two contact aureole rocks: implications for controls on melt localization and deformation
Authors: Marchildon N. , Brown M. 
Published: March 2003

AbstractThe grain‐scale spatial arrangement of melt in layer‐parallel leucosomes in two anatectic rocks from two different contact aureoles located in central Maine, USA, is documented and used to constrain the controls on grain‐scale melt localization. The spatial distribution of grain‐scale melt is inferred from microstructural criteria for recognition of mineral pseudomorphs after melt and mineral grains of the solid matrix that hosted the melt. In both rocks, feldspar mimics the grain‐scale distribution of melt, and quartz is the major constituent of the solid matrix. The feldspar pockets consist of individual feldspar grains or aggregates of feldspar grains that show cuspate outlines. They have low average width/length ratios (0.54 and 0.55, respectively), and are interstitial between more rounded and equant (width/length ratios 0.65 for both samples) quartz grains. In two dimensions, the feldspar pockets extend over distances equivalent to multiple quartz grain diameters, possibly forming a connected three‐dimensional intergranular network. Both samples show similar mesoscopic structural elements and in both samples the feldspar pockets have a shape‐preferred orientation. In one sample, feldspar inferred to replace melt is aligned subparallel to the shape‐preferred orientation of quartz, indicating that pre‐ or syn‐anatectic strain controlled the grain‐scale distribution of melt. In the other sample, the preferred orientation of feldspar inferred to replace melt is different from the orientations of all other mesoscopic or microscopic structures in the rock, indicating that differential stress controlled grain‐scale melt localization. This is probably facilitated by conditions of higher differential stress, which may have promoted microfracturing. Grain‐scale melt distribution and inferred melt localization controls give insight into possible grain‐scale deformation mechanisms in melt‐bearing rocks. Application of these results to the interpretation of deep crustal anatectic rocks suggests that grain‐scale melt distribution should be controlled primarily by pre‐ or syn‐anatectic deformation. Feedback relations between melt localization and deformation are to be expected, with important implications for deformation and tectonic evolution of melt‐bearing rocks.
Calc‐silicate reactions and bedding‐controlled isotopic exchange in the Notch Peak aureole, Utah: implications for differential fluid fluxes with metamorphic grade
Authors: Nabelek P. I. 
Published: March 2003

AbstractFluid compositions and bedding‐scale patterns of fluid flow during contact metamorphism of the Weeks Formation in the Notch Peak aureole, Utah, were determined from mineralogy and stable isotope compositions. The Weeks Formation contains calc‐silicate and nearly pure carbonate layers that are interbedded on centimetre to decimetre scales. The prograde metamorphic sequence is characterized by the appearance of phlogopite, diopside, and wollastonite. By accounting for the solution properties of Fe, it is shown that the tremolite stability field was very narrow and perhaps absent in the prograde sequence. Unshifted oxygen and carbon isotopic ratios in calcite and silicate minerals at all grades, except above the wollastonite isograd, show that there was little to no infiltration of disequilibrium fluids. The fluid composition is poorly constrained, but X(CO2)fluid must have been >0.1, as indicated by the absence of talc, and has probably increased with progress of decarbonation reactions.The occurrence of scapolite and oxidation of graphite in calc‐silicate beds of the upper diopside zone provide the first evidence for limited infiltration of external aqueous fluids. Significantly larger amounts of aqueous fluid infiltrated the wollastonite zone. The aqueous fluids are recorded by the presence of vesuvianite, large decreases in δ18O values of silicate minerals from c. 16‰ in the diopside zone to c. 10‰ in the wollastonite zone, and extensive oxidation of graphite. The carbonate beds interacted with the fluids only along margins where graphite was destroyed, calcite coarsened, and isotopic ratios shifted.The wollastonite isograd represents a boundary between a high aqueous fluid‐flux region on its higher‐grade side and a low fluid‐flux region on its lower‐grade side. Preferential flow of aqueous fluids within the wollastonite zone was promoted by permeability created by the wollastonite‐forming reaction and the natural tendency of fluids to flow upward and down‐temperature near the intrusion‐wall rock contact.
Regional‐scale Grenvillian‐age UHT metamorphism in the Mollendo–Camana block (basement of the Peruvian Andes)
Authors: Martignole J , Martelat J.‐E 
Published: March 2003

AbstractThe Mollendo–Camana Block (MCB) is a 50 × 150 km Precambrian inlier of the Andean belt that outcrops along the Pacific coast of southern Peru. It consists of stromatic migmatites of Paleoproterozoic heritage intensely metamorphosed during the Grenville event (c. 1 Ga; U‐Pb and U‐Th‐Pb ages on zircon and monazite). In the migmatites, aluminous mesosomes (FMAS) and quartzofeldspathic leucosomes (KFMASH), contain various amounts of K‐feldspar (Kfs), orthopyroxene (XMg Opx = 0.86), plagioclase (Pl), sillimanite (Sil; exceptionally kyanite, Ky) ilmenite (Ilm), magnetite (Mag), quartz (Qtz), and minor amounts of garnet (XMg Grt = 0.60), sapphirine (XMg Spr = 0.87), cordierite (XMg Crd = 0.92) and biotite (XMg Bt = 0.83). The ubiquitous peak mineral assemblage is Opx‐Sil‐Kfs‐Qtz‐(± Grt) in most of the MCB, which, together with the high Al content of orthopyroxene (10% Al2O3) and the local coexistence of sapphirine‐quartz, attest to regional UHT metamorphism (> 900 °C) at pressures in excess of 1.0 GPa. Fluid‐absent melting of biotite is responsible for the massive production of orthopyroxene that proceeded until exhaustion of biotite (and most of the garnet) in the southern part of the MCB (Mollendo‐Cocachacra areas). In this area, a first stage of decompression from 1.1–1.2 to 0.8–0.9 GPa at temperatures in excess of 950 °C, is marked by the breakdown of Sil‐Opx to Spr‐Opx‐Crd assemblages according to several bivariant FMAS reactions. High‐T decompression is also shown by Mg‐rich garnet being replaced by Crd‐Spr‐ and Crd‐Opx‐bearing symplectites, and reacting with quartz to produce low‐Al‐Opx‐Sil symplectites in quartz‐rich migmatites. Neither osumilite nor spinel‐quartz assemblages being formed, isobaric cooling at about 0.9 GPa probably followed the initial decompression and proceeded with massive precipitation of melts towards the (Os) invariant point, as demonstrated by Bt‐Qtz‐(± pl) symplectites in quartz‐rich migmatites (melt + Opx + Sil = Bt + Grt + Kfs + Qtz). Finally, Opx rims around secondary biotite attest to late fluid‐absent melting, compatible with a second stage of decompression below 900 °C. The two stages of decompression are interpreted as due to rapid tectonic denudation whereas the regional extent of UHT metamorphism in the area, probably results from large‐scale penetration of hot asthenospheric mantle at the base of an over‐thickened crust.