bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climate change and greenhouse gases
Authors: Ledley Tamara S. , Sundquist Eric T. , Schwartz Stephen E. , Hall Dorothy K. , Fellows Jack D. , Killeen Timothy L. 
Published: September 2002

Infrared (IR) active gases, principally water vapor (H2O), carbon dioxide (CO2), and ozone (O3), naturally present in the Earth's atmosphere, absorb thermal IR radiation emitted by the Earth's surface and atmosphere. The atmosphere is warmed by this mechanism and, in turn, emits IR radiation, with a significant portion of this energy acting to warm the surface and the lower atmosphere. As a consequence the average surface air temperature of the Earth is about 30°C higher than it would be without atmospheric absorption and reradiation of IR energy [Kellogg, 1996; Peixoto and Oort, 1992; Henderson‐Sellers and Robinson, 1986].This phenomenon is popularly known as the “greenhouse effect,” and the IR active gases responsible for the effect are likewise referred to as “greenhouse gases.” The rapid increase in concentrations of greenhouse gases since the industrial period began has given rise to concern over potential resultant climate changes.
An overview of the current drugs scene
Authors: Edgar D. F. 
Published: September 2002

SummaryOphthalmic drugs, both diagnostic and therapeutic, play a central role in new developments in optometry, particularly as practitioners extend their involvement in primary care. Optometrists now dilate more patients in routine practice, and this brings increasing concern about the risk of provoking acute closed angle glaucoma (CAG) attacks. It would seem that the risk of inducing acute CAG is far outweighed by the potential benefit of examining the eye through a dilated pupil. Driving difficulties, reported subjectively to be the result of glare, are frequently encountered by patients after dilation, and advice from the College of Optometrists is welcomed. The local anaesthetic proxymetacaine 0.5% is now marketed in the UK in preservative‐free unit‐dose applicators both alone and in combination with fluorescein, and is a more comfortable alternative to existing anaesthetics in unit‐dose form. The second half of this paper includes a summary of the background to recent developments, as the UK profession takes its first steps towards the use of ocular therapeutic agents. Finally, some exciting new therapeutic preparations for use in the treatment of glaucoma, allergic eye disease, and dry eye conditions are discussed.
New developments in retinal drusen
Authors: Gibson J. M. 
Published: September 2002

SummaryRetinal drusen are an important manifestation of age‐related maculopathy, and increase with ageing. Recent studies have shown that gentle laser photocoagulation can lead to resolution of soft drusen and may lessen the high risk of development of choroidal neovascularisation in these cases. Laser induced regression of retinal drusen appears to be a safe technique, but no long term results are yet available. Retinal drusen may also occur as a dominantly inherited disorder and current evidence suggests that these represent more than one disorder. Misclassification of retinal drusen as retinal exudates is an important cause of false positive referral in diabetic retinopathy screening programmes.
Investigating and managing the child with special needs
Authors: Woodhouse J. Margaret 
Published: September 2002

SummaryChildren with disabilities are much more at risk of eye and vision problems than are able children. These problems can take the form of ‘optical’ defects such as refractive errors and poor accommodation. Thus children with all forms of special needs not only have a right to Optometric services, but have a greater need than the rest of the population. This paper presents recent data on the defects found specifically in children with Down's Syndrome, (but likely to occur in other children) and provides general guidelines for Optometrists working with children with special needs.
Contrast and glare sensitivity in diabetic patients with and without pan‐retinal photocoagulation
Authors: Mackie S. W. , Walsh G. 
Published: September 2002

SummaryPatients with diabetes mellitus often have ophthalmic dysfunction, as diabetic eye disease can affect the majority of the ocular structures. The present study investigated contrast sensitivity (experiment 1) and glare sensitivity (experiment 2) using Pelli‐Robson and Bailey‐Lovie charts in normal and diabetic patients with a range of degrees of ischaemic retinopathy (n=220). Contrast sensitivity thresholds reduced and glare sensitivity progressively increased throughout the range from normal to advanced stages of diabetic eye disease. However, the reduction in contrast sensitivity between adjacent groups was not significant (P>0.10). Conversely, glare sensitivity was found to be greater in those diabetic patients who had received laser treatment (P=0.001). The potential use of both tests is discussed.
Contrast restoration model for contrast matching of cosine gratings of various spatial frequencies and areas
Authors: Näsänen Risto , Tiippana Kaisa , Rovamo Jyrki 
Published: September 2002

SummaryThe purpose of the model presented in this paper is to explain the well known fact that perceived contrast becomes independent of optical low‐pass and neural high‐pass filtering as well as areal integration with increasing stimulus contrast. In the model we assume that perceived contrast is computed by two different parallel mechanisms. One of them integrates signal information across space to improve the signal‐to‐noise ratio and is affected by the optical low‐pass and neural high‐pass filtering. The other mechanism estimates external local contrast by using inverse filtering. These two factors are combined by a ‘restoration’ mechanism so that the first mechanism affects the perception of low contrast and the latter that of high contrast stimuli. The behaviour of the model was tested against experimental results obtained with normal human observers. At low contrast levels, contrast matching curves were similar in shape to the detection threshold curves both as a function of the spatial frequency and area of the grating. At high contrast levels, contrast matches became physically correct. The model described the experimental results accurately.
Vergence control across saccades in dyslexic adults
Authors: Moores Elisabeth , Frisby John P. , Buckley David , Reynolds Emma , Fawcett Angela 
Published: September 2002

SummaryMany aspects of vision have been investigated in developmental dyslexia. Some research suggests deficits in vergence control (e.g. Buzzelli, 1991,Optom. Vision Sci.68, 842–846), although ability to control vergence across saccades has not yet been investigated. We have explored this question indirectly using Enright's (1996Vision Res.36, 307–312.) sequential stereopsis task. The task requires observers to set two adjacent targets (whose textures cannot be resolved simultaneously if either is fixated) to appear equi‐distant. Enright has argued that sequential stereopsis stereoacuity thresholds offer an indication of vergence control across saccades. We report two experiments using a total of 17 dyslexic and 18 control adults. Performance was measured on a sequential stereopsis task and an ordinary ‘simultaneous’ stereopsis task. No significant differences between groups were found. However, whereas practice of the sequential task lowered control group thresholds on the simultaneous task, for the dyslexic group it significantly raised thresholds, suggesting that visual fatigue is especially important in investigations of visual functions in dyslexia. Although the small samples used limit conclusions at this stage, the main sequential stereopsis results suggest that, if Enright is correct, dyslexic adults can show normal vergence control across saccades.
Errors in determining the direction of the visual axis in the presence of defocus
Authors: Atchison David A. , Smith George , Charman W. Neil 
Published: September 2002

SummaryThe visual axis is the ray path from the fixation point to the fovea by way of the nodal points. Such a ray path does not exist in unaccommodated vision when the fixation point does not coincide with the far point of the eye because of induced or natural defocus. Nevertheless an approximation to the visual axis can be obtained by the position of a small pupil close to the cornea for which a bichromatic vernier target appears correctly aligned. When the visual axis is determined, an eye rotation from the usual fixation position must occur, which is reversed upon removing the small pupil. Upon engaging in any experiments for which the visual axis is then used as a reference, there is an error in this reference position. We develop simple paraxial equations to estimate this error. We show that these equations have good accuracy. The error associated with locating the visual axis at the cornea is 0.002 mm per dioptre of defocus, which is small enough to be ignored.
Vergence adaptation and the clinical AC/A ratio
Authors: Rosenfield Mark , Rappon Joseph M. , Carrel Meredith F. 
Published: September 2002

SummaryThe accuracy of the gradient technique for measuring the clinical accommodative convergence to accommodation (AC/A) ratio is dependent upon obtaining veridical heterophoria measurements. However, previous studies have demonstrated that the sustained output of slow fusional vergence, which may take several minutes or even hours to decay, can bias heterophoria assessment. In the clinical setting, it is usual to estimate the AC/A ratio after just a few seconds of dissociation. This study investigated whether the slow fusional vergence response alters this crosslink ratio by comparing values of AC/A measured both before and immediately after a 1‐hr period of continuous monocular occlusion. Sustained occlusion produced a significant change in near heterophoria in 10 out of the 21 subjects examined, but no significant change in AC/A was observed in either the adapting or non‐adapting subgroups. Accordingly, while the sustained output of slow fusional vergence will influence clinical measurements of heterophoria, its presence does not alter the stimulus AC/A ratio significantly.
Characteristics of a paediatric low vision population in a private eye hospital in India
Authors: Gothwal Vijaya K. , Herse Peter 
Published: September 2002

SummaryWhile private hospitals provide an important access point for low vision services for children in urban India, little is known about this service delivery route. A cross sectional survey was done of consecutive records of 220 children presenting at a newly opened paediatric low vision centre in a private eye hospital in Hyderabad. On presentation, 49% of the children were classified as moderately visually impaired, 31% were severely visually impaired and 20% were blind. The four major causes of visual impairment were the hereditary/genetic conditions of congenital glaucoma, hereditary macular degeneration, retinitis pigmentosa and albinism. Approach magnification was sufficient for required near tasks in all pre‐school children and about 50% of school children. Provision of a distance refraction decreased the prevalence of severe visual impairment and blindness by 31%. The most commonly prescribed low vision devices were spectacles indicating a key role for optometry in the management of visual impairment in Indian children. Establishment of low vision clinics in existing Indian eye hospitals using associated optometric staff would be a cost effective method to minimise visual impairment in Indian children.
Spatial location studies on the chemical composition of human tear ferns
Authors: Pearce E. Ian , Tomlinson Alan 
Published: September 2002

SummaryTear ferns are the patterns formed when tears are allowed to dry on a clean smooth surface. The patterns have been categorised according to confluence of pattern,with less confluent ferns indicative of tear film abnormalities. Little is known about the mechanism that gives rise to this phenomenon. Previous work has concentrated on correlation of alterations in tear film composition on the ferning phenomenon. The present study takes a new approach by analysing the locations of chemical elements in the fern to understand how the ferns form. By means of SEM coupled with EDXA, Na, K and Cl were detected within the fern. Sulphur, indicative of the presence of macromolecules such as mucins and proteins, was only found at the very periphery of the dry tear drop. The results suggest that macromolecules do not play a direct role in the formation of the ferns. A model is put forward to explain the observation whereby proteins and mucins are precipitated selectively by increasing salt concentration at the drop margin.
Oral and silent reading performance with macular degeneration
Authors: Lovie‐Kitchin Jan E. , Bowers Alex R. , Woods Russell L. 
Published: September 2002

SummaryPrevious studies have shown that reading rate for very large print (6°, 1.86 logMAR character size) is a strong predictor of oral reading rate with low vision devices (LVDs). We investigated whether this would apply using large print sizes more readily available in clinical situations (e.g. 2°, 1.4 logMAR), for subjects with macular degeneration. We assessed rauding rates—reading for understanding. A combination of near word visual acuity and large print reading rate (without LVDs) provided the best prediction of oral rauding rates (with LVDs). However, near word visual acuity alone was almost as good. Similarly, silent rauding rate was predicted best by near word visual acuity alone. We give near visual acuity limits as a clinical guide to expected oral and silent reading performance with LVDs for patients with macular degeneration.
Effects of prediction on timing and dynamics of vergence eye movements
Authors: Yuan Weihong , Semmlow John L. , Munoz Paula 
Published: September 2002

SummaryPeriodic square waves were used to generate predictable vergence eye movement responses. The timing and dynamic characteristics of vergence eye movement responses to predictable and non‐predictable stimuli were compared. Results showed significant changes in timing characteristics along with a highly characteristic anticipatory movement in the early part of predictable vergence responses. This phenomenon is similar to that seen in saccadic eye movements and appears to influence the timing and dynamics of the subsequent vergence response. A model‐based analysis of dynamics showed that the pulse width, pulse gain, and step gain of the motor command signal did not show major differences between predictable and non‐predictable response. However, other model parameters related to the acceleration of the response showed a substantial decrease when the movements were predictive.
Optical Fourier filtering for whole lens assessment of progressive power lenses
Authors: Spiers T. , Hull C. C. 
Published: September 2002

SummaryFour binary filter designs for use in an optical Fourier filtering set‐up were evaluated when taking quantitative measurements and when qualitatively mapping the power variation of progressive power lenses (PPLs). The binary filters tested were concentric ring, linear grating, grid and “chevron” designs. The chevron filter was considered best for quantitative measurements since it permitted a vernier acuity task to be used for measuring the fringe spacing, significantly reducing errors, and it also gave information on the polarity of the lens power. The linear grating filter was considered best for qualitatively evaluating the power variation. Optical Fourier filtering and a Nidek automatic focimeter were then used to measure the powers in the distance and near portions of five PPLs of differing design. Mean measurement error was 0.04 D with a maximum value of 0.13 D. Good qualitative agreement was found between the iso‐cylinder plots provided by the manufacturer and the Fourier filter fringe patterns for the PPLs indicating that optical Fourier filtering provides the ability to map the power distribution across the entire lens aperture without the need for multiple point measurements. Arguments are presented that demonstrate that it should be possible to derive both iso‐sphere and iso‐cylinder plots from the binary filter patterns.
Spectral filters in low‐vision correction
Authors: Rosenblum Y.Z. , Zak P.P. , Ostrovsky M.A. , Smolyaninova I.L. , Bora E.V. , Dyadina U.V. , Trofimova N.N. , Aliyev A.‐G.D. 
Published: September 2002

SummaryColoured filters are used to protect the lens, retina and other ocular tissues against the hazard of light damage and to improve the quality of vision mainly in cases of ocular media opacities.Four types of yellow, amber and orange filters have been designed as tinted glasses, shields and colour covering of spectacles. They were tested on 15 adult patients with partial cataract and on 80 children with congenital pathology (i.e. macular hypoplasia, albinism, aphakia after congenital cataract). The majority of the children had nystagmus. The filters with particular spectral characteristics provide reduction of light intensity in the light‐damaging range by at least a factor of five. Optimal filters were selected by examination of visual acuity, contrast frequency sensitivity, glare sensitivity and subjective selection by the patients. The effects of filters were: 11–43% increase in corrected visual acuity, 27–34% increase in contrast sensitivity function (CSF) for all frequencies and a marked reduction in glare sensitivity. All patients reported subjective improvement including reduction of photophobia, eye‐strain and eye discomfort. It is concluded that coloured filters are able to contribute substantially to rehabilitation of low‐vision patients.
Isomer Effect of the Production of Negative Ions from C6H4XY and C6H10X2 (X, Y = Halogen)
Authors: Nakagawa Seiko 
Published: September 2002

Abstract
The temperature dependence of the formation of negative ions from C6H4XY (X, Y = Cl, Br, I) and cyclo-C6H10X2 (X = Cl, Br) was studied using negative chemical ionization mass spectrometry. The heavier halide ion was mainly observed for C6H4XY. The production rate of halide ions became greater in the order C6H4ClBr &lt;&lt; C6H4ClI &lt; C6H4BrI. The relative production rate of the major ions between isomers is related to the character of the substituted halogen atom in the system. The main observed ion was X− for C6H10X2. The production rate of halide ions increased in the order cyclo-cis-1,4-C6H10Cl2 &lt; cyclo-trans-1,4-C6H10Cl2 ∼ cyclo-trans-1,2-C6H10Cl2 &lt;&lt; cyclo-trans-1,2-C6H10Br2. For cyclo-trans-1,2-C6H10Br2, not only Br−, but also Br2−, was observed. Four-center elimination with rotation of the C–Br bond seemed to occur when Br2− was produced from cyclo-trans-1,2-C6H10Br2.
cis-Dioxomolybdenum(VI) Complex with a Tripod-Like Tetradentate Ligand, N′, N′-Bis(2-hydroxy-3,5-dimethylbenzyl)-N, N-dimethylethylenediamine
Authors: Lim Jong-Wan , Park Yu-Chul , Mikuriya Masahiro 
Published: September 2002

Abstract
A cis-dioxomolybdenum(VI) complex with N′, N′-bis(2-hydroxy-3,5-dimethylbenzyl)-N, N-dimethylethylenediamine (H2L), cis-[MoO2(L)], was synthesized and characterized by measurements of NMR, infrared, and electronic spectra. The X-ray crystal structure shows that the compound has a distorted octahedral geometry with an N2O4 coordination environment.
Food consumption by clupeids in the Central Baltic: evidence for top-down control?
Authors: Möllmann Christian , Köster Friedrich W. 
Published: September 2002

Abstract
Considerable changes have taken place in the pelagic ecosystem of the Central Baltic Sea during the last decade. Owing to a combination of high fishing pressure and unfavourable hydrographic conditions, the cod (Gadus morhua) stock as the top predator in the system was reduced from a high level in the early 1980s to its lowest size on record in the early 1990s. The preferred prey species sprat (Sprattus sprattus) showed a significant increase in population size since the late 1980s to the highest level on record in recent years, while the herring (Clupea harengus), another important planktivore in the system, did not show such a response. We investigate whether fluctuations in clupeid stock size cascade down to the trophic level of mesozooplankton, based on stomach content data and daily ration estimates in combination with stock sizes estimated from Multispecies Virtual Population Analysis. Estimates of daily consumption by the populations of the two species for 1978–1990 were compared with standing stocks of mesozooplankton species. No evidence was found for food limitation as might be expected if clupeids exert a strong top-down control on mesozooplankton. Also no influence on interannual variability of mesozooplankton abundance was detected. However, predation did contribute to the seasonal development of two copepod species (Pseudocalanus elongatus and Temora longicornis).
Biology and functional morphology of the watering pot shell Brechites vaginiferus (Bivalvia: Anomalodesmata: Clavagelloidea)
Authors: Morton Brian 
Published: September 2002

AbstractLiving individuals of the bivalve ‘watering pot’ superfamily Clavagelloidea were collected from Withnell Bay, Burrup Peninsula, Dampier Archipelago, Western Australia. Details of the anatomy suggest that, in most respects, Brechites vaginiferus is a typical filter‐feeding bivalve, albeit encased in a tube of its own secretion. The true shell is tiny (∼ 4 mm long) and surrounded by a ‘saddle’ of initially‐secreted adult shell. To this is fused, by an internally produced layer of calcium carbonate, the adventitious tube which comprises a single layer, confirming that it is produced only once. Posteriorly, however, it can be added to internally as ‘plaited ruffles’ creating a multi‐layered structure. The anterior watering pot comprises a perforated plate fringed by tubules, with a small pedal aperture. Brechites vaginiferus pumps interstitial water into the mantle cavity via the watering pot, at least principally, not out of it as previously thought. In this way, the animal is either tapping an interstitial source of accessory food, or aerating the anterior end of its burrow (or both). It has also been demonstrated, however, that pumping interstitial water into the mantle cavity via the pedal gape results in hydraulic pressures being built up that extend the siphons. The pedal disc pump, therefore, acts in this amyarian bivalve in the same way as the adductor muscles do in more typical species. The ctenidia collect suspended material in the usual way from seawater and from interstitial water: they do not, however, possess chemoautotrophic sulphur‐oxidizing bacteria, and the species is thus not using sulphur as an energy source. Pedal gape feeding is considered to be the ancestral condition not only in the earliest anomalodesmatans, e.g. the Pholadomyidae, but also the autobranchs in general. This has been refined in the Clavagelloidea to create the unique form of the adventitious tube, its watering pot and a wholly surprising lifestyle. Tube form in B. vaginiferus varies in relation to habitat occupied. Its major habitat on Withnell Bay, however, is the riffles of a high‐salinity stream draining down the mangrove‐fringed shore from the semi‐arid land behind. Although much more is now known about B. vaginiferus and ‘watering pot’ shells, no pre‐tube juvenile is known and awaits discovery to confirm hypothesized life‐history details.
Suicide in late life
Authors: Snowdon John 
Published: September 2002

If we can better understand why people kill themselves, it should be possible to
reduce suicide rates. The major aim of this article is to consider whether any factors
associated with higher rates of suicide in old age are amenable to preventive interventions.It is said that epidemiology is the basic science of prevention. Multiple
interacting factors contribute to the causation of suicide, though commonly, in the
individual case, a single circumstance or condition can be identified as the major
precipitant of suicidal behaviour. Cross-sectional studies may reveal factors that
correlate with high suicide rates in particular populations, while long-term studies
can show associations between changes in suicide rate and in socio-environmental
conditions.