bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix‐based calculation scheme for toric intraocular lenses*
Authors: Langenbucher Achim , Reese Sven , Sauer Tomas , Seitz Berthold 
Published: October 2004

AbstractBackground and purpose:  While a number of intraocular lens power prediction formulas are well established for determination of spherical lenses, no common strategy is published for the computation of toric intraocular lenses. The purpose of this study is to describe a paraxial computing scheme using 4 × 4 system matrices to describe the ‘optical system eye’ containing astigmatic refractive surfaces with their axes at random.Methods:  Based on the definition of a centred optical system in the paraxial Gaussian space containing astigmatic surfaces using 4 × 4 refraction and translation matrices, we derived a methodology for calculating the refractive power of thin and thick toric intraocular lenses by solving a linear equation system. In a second step, we derived a methodology for prediction of the residual spectacle refraction after implantation of any toric lens implant with any orientation.Results:  The capabilities of this computing scheme are demonstrated with three examples. In example 1 we calculate a ‘thin toric lens’ for compensation of a corneal astigmatism to achieve a spherical target refraction. In example 2 we compute a ‘thick toric lens’, which has to compensate for an oblique corneal astigmatism and rotate the spectacle cylinder to the ‘against the rule’ position to enhance near vision. In example 3 we predict the residual refraction at the corneal plane after implantation of a thick toric lens, when the cylinder of the lens implant is compensating the corneal cylinder in part and the axis of implantation is not fully aligned with the axis of the corneal astigmatism.Conclusion:  We present an en bloc matrix‐based strategy for the calculation of thick or thin toric intraocular lenses, with the flexibility of crossing an unlimited number of cylinders with restrictions to paraxial optics. The resulting system matrix S is written as a product of 4 × 4 refraction and translation matrices. Residual refraction at the corneal (contact lens) or spectacle plane can be derived by inverting the order of matrices for calculation of the system matrix.
Measurement of refractive error and accommodation with the photorefractor PowerRef II
Authors: Jainta Stephanie , Jaschinski Wolfgang , Hoormann Jörg 
Published: October 2004

AbstractThe infrared photorefractor PowerRef II (PR II; PlusoptiX AG, Nürnberg, Germany) uses the principle of eccentric photorefraction. In eight subjects the mean non‐cycloplegic refraction measured with the ‘Full Scan’ mode of the PR II at a far viewing distance (0.2 D) was significantly more hypermetropic by 0.6 D compared with subjective refraction. The mean accommodation differed by about this same amount between the PR II and the Canon R1 at three different viewing distances (3, 2 and 1 D). The PR II refraction at the 1 m reference distance was 0.25 D more hypermetropic compared with the subjective refraction at far (5 m); these measures were moderately correlated (r = 0.7). To determine temporal changes, the ‘Dynamic Scan’ mode was used over a 2‐min period: the mean intraindividual standard deviation was 0.32 mm for pupil diameter and 0.29 D for accommodation, while the absolute measurement error of the ‘Dynamic Scan’ was found to be <0.12 D for the accommodation data. Interindividual reliabilities were satisfactory. However, the PR II did not provide a continuous stream of data and the specified sampling frequency of 25 Hz was rarely realized.
Microfluctuations of wavefront aberrations of the eye
Authors: Zhu Mingxia , Collins Michael J. , Robert Iskander D. 
Published: October 2004

AbstractTo investigate fluctuations in the wavefront aberrations of the eye and their relation to pulse and respiration frequencies we used a wavefront sensor to measure the dynamics of the Zernike aberrations up to the polynomial fourth radial order. Simultaneously, the subject's pulse rate was measured, from which the instantaneous heart rate was derived. We used an auto‐regressive process to derive the power spectra of the Zernike aberration signals, as well as pulse and instantaneous heart rate signals. Linear regression analysis was performed between the frequency components of Zernike aberrations and the pulse and instantaneous heart rate frequencies. Cross‐spectrum density and coherence analyses were also applied to investigate the relation between fluctuations of wavefront aberrations, and pulse and instantaneous heart rate. The correlations between fluctuations of individual Zernike aberrations were also determined. A frequency component of all Zernike aberrations up to the fourth radial order was found to be significantly correlated with the pulse frequency (all R2 ≥ 0.51, p < 0.02), and a frequency component of nine out of 12 Zernike aberrations was also significantly correlated with instantaneous heart rate frequency (all R2 ≥ 0.46, p < 0.05). The major correlations among Zernike aberrations occurred between second‐order and fourth‐order aberrations with the same angular frequencies. Higher order aberrations appear to be related to the cardiopulmonary system in a similar way to that reported for the accommodation signal and pupil fluctuations.
Macular pigment optical density in young Chinese adults
Authors: Tang Churk‐Yan , Yip Hoi‐shan , Poon Ming‐yeung , Yau Wai‐lam , Yap Maurice K. H. 
Published: October 2004

AbstractPurpose:  The purpose of this study was to determine the macular pigment optical density (MPOD) in a group of Chinese subjects using a simple customized light emitting diode‐based device.Methods:  Heterochromatic flicker photometry was used in this study. With a 1° diameter circular test stimulus, MPOD was estimated by comparing the relative sensitivities to a blue light, against a green reference, between foveal and parafoveal 4° temporal locations. Fixed alternating frequencies were used. Repeatability was determined on a small group of subjects. A further group of 67 young healthy subjects provided data for MPOD norms.Results:  All results were corrected to the common MPOD reference wavelength of 460 nm. The group‐averaged MPOD was 0.48 (S.D. 0.23). We found no gender difference in MPOD. The coefficient of variability was 7.2–8.0% and the coefficient of repeatability was 0.12.Conclusions:  The MPOD of Chinese subjects did not differ greatly from the reported MPOD in white subjects.
Reliability, normative data, and the effect of age‐related macular disease on the Eger Macular Stressometer photostress recovery time
Authors: Bartlett Hannah , Davies Leon N. , Eperjesi Frank 
Published: October 2004

AbstractPurpose:  To assess repeatability and reproducibility, to determine normative data, and to investigate the effect of age‐related macular disease, compared with normals, on photostress recovery time measured using the Eger Macular Stressometer (EMS).Method:  The study population comprised 49 healthy eyes of 49 participants. Four EMS measurements were taken in two sessions separated by 1 h by two practitioners, with reversal of order in the second session. EMS readings were also taken from 17 age‐related maculopathy (ARM), and 12 age‐related macular degeneration (AMD), affected eyes.Results:  EMS readings are repeatable to within ±7 s. There is a statistically significant difference between controls and ARM affected eyes (t = 2.169, p = 0.045), and AMD affected eyes (t = 2.817, p = 0.016). The EMS is highly specific, and demonstrates sensitivity of 29% for ARM, and 50% for AMD.Conclusions:  The EMS may be a useful screening test for ARM, however, direct illumination of the macula of greater intensity and longer duration may yield less variable results.
MODELS OF STOCK MARKET PREDICTABILITY
Authors: Malkiel Burton G. 
Published: October 2004

AbstractI briefly review the success of past studies purporting to explain equity valuations and predict future equity returns. The Campbell‐Shiller mean reversion models are contrasted with an expanded version of the so‐called Federal Reserve model. At least from 1970 to 2003, Federal Reserve–type models did somewhat better at predicting long‐horizon returns than did a mean reversion model based on dividend yields and price‐earnings multiples. However, timing investment strategies based on any of these prediction models do no better than a buy‐and‐hold strategy. Although some predictability of returns exists, there is no evidence of any systematic inefficiency that would enable investors to earn excess returns.
CAN INEFFICIENT TRADERS CREATE VALUE?
Authors: Krishnan C. N. V. 
Published: October 2004

AbstractI examine the aggregate expected profit generated by informed traders of diverse ability in a competitive market. I assume that efficient traders get perfect information on asset values whereas inefficient traders get noisy information. In the presence of order size restrictions, I show that the aggregate expected profit generated by efficient and inefficient traders together can be higher than that generated by efficient traders alone. Thus, inefficient traders can create value in a constrained trading environment.
ANALYZING STOCK MARKET VOLATILITY USING EXTREME‐DAY MEASURES
Authors: Jones Charles P. , Walker Mark D. , Wilson Jack W. 
Published: October 2004

AbstractWe develop a simple measure of volatility based on extreme‐day returns and apply it to market returns from 1885 to 2002. Because returns are not normally distributed, the extreme‐day measure, which is distribution free, might provide a better measure of stock market risk than the traditional standard deviation. The extreme‐day measure more accurately explains investor behavior relative to standard deviation as shown by equity fund flows, and we find evidence that large negative changes appear to influence investor behavior more than large positive changes.
Riparian Restoration in the Western United States: Overview and Perspective
Authors: Goodwin Craig N. , Hawkins Charles P. , Kershner Jeffrey L. 
Published: October 2004

AbstractThis historical and conceptual overview of riparian ecosystem restoration discusses how riparian ecosystems have been defined, describes the hydrologic, geomorphic, and biotic processes that create and maintain riparian ecosystems of the western USA, identifies the main types of anthropogenic disturbances occurring in these ecosystems, and provides an overview of restoration methods for each disturbance type. We suggest that riparian ecosystems consist of two zones: Zone I occupies the active floodplain and is frequently inundated and Zone I1 extends from the active floodplain to the valley wall. Successful restoration depends on understanding the physical and biological processes that influence natural riparian ecosystems and the types of disturbance that have degraded riparian areas. Thus we recommend adopting a process‐based approach for riparian restoration. Disturbances to riparian ecosystems in the western USA result from streamflow modifications by dams, reservoirs, and diversions; stream channelization; direct modification of the riparian ecosystem; and watershed disturbances. Four topics should be addressed to advance the state of science for restoration of riparian ecosystems: (1) interdisciplinary approaches, (2) a unified framework, (3) a better understanding of fundamental riparian ecosystem processes, and (4) restoration potential more closely related to disturbance type. Three issues should be considered regarding the cause of the degraded environment: (1) the location of the causative disturbance with respect to the degraded riparian area, (2) whether the disturbance is ongoing or can be eliminated, and (3) whether or not recovery will occur naturally if the disturbance is removed.
Prioritizing Watersheds in Oregon for Salmon Restoration
Authors: Nehlsen Willa 
Published: October 2004

AbstractThis paper describes an ecosystem approach (the Bradbury framework) to prioritizing watersheds for watershed restoration and salmon recovery, and gives an example of its application. The framework was applied at three spatial scales (in descending order) to prioritize (1) river basins within the north coast geographic area of Oregon (USA), (2) watersheds within the Tillamook Bay basin, and (3) restoration activities at the watershed level. Implementing the framework identified the Nehalem and Tillamook Bay basins as high priority for the north coast of Oregon. Within the Tillamook Bay basin, the Wilson, Kilchis, and Trask river watersheds emerged as high priority. Preliminary analysis indicated that controlling sediment sources by addressing upland road conditions and allowing floodplain and riparian ecosystems to recover are highest priority protection and restoration activities within the Tillamook Bay basin. The sample application demonstrates that an ecosystem approach (the Bradbury framework) is particularly advantageous where data are limited, although previous identification of relatively intact areas is required. Implementing the framework is intended to lead to restoration of native species, but it may not provide immediate assistance for some species or populations of concern.
Two‐Stage System for Prioritizing Riparian Restoration at the Stream Reach and Community Scales
Authors: Harris Richard , Olson Craig 
Published: October 2004

AbstractThis paper describes a two‐stage system for prioritizing stream reaches and riparian communities along a given river for protection or restoration. The system uses associations between geomorphology and riparian vegetation at stream reach and community scales as a basis for defining reference conditions. First‐stage reach classification involves collecting and analyzing data from topographic maps and aerial photographs. These data, along with judgment‐based criteria for ranking reaches relative to reference conditions, are used to classify stream reaches as suitable for protection, recommended for mitigation or restoration within existing site‐specific regulatory procedures, or requiring further analysis to evaluate community‐scale restoration needs. Second‐stage field sampling is conducted on the reaches needing further analysis to determine the riparian communities present, the associations between communities and floodplain landforms, and reference community conditions. This stage requires collection of field data on geomorphic conditions, plant species composition, and plant community structure. Cluster analysis or a comparable technique is used to classify plant communities associated with floodplain landforms and identify reference conditions for each landform. Community structure and species composition are compared to reference conditions to define restoration possibilities at the community scale. The combined results from stream reach and community‐scale analysis provide a strategy for protecting and restoring riparian resources for a whole river. Implementation requires further site‐specific information on hydrology, geomorphology, and other factors.
Vulnerability of Riparian Vegetation to Catastrophic Flooding: Implications for Riparian Restoration
Authors: Hawkins Charles P. , Bartz Kate L. , Neale Christopher M. U. 
Published: October 2004

AbstractIn this study, we examined the site‐specific effects of a large episodic flood on the riparian vegetation within the floodplain of the San Luis Rey River in southern California. Using multispectral airborne videography, we quantified percent cover of riparian vegetation, cultivated agricultural land, urban surfaces, upland vegetation, bare soil, and water within 22 sections of floodplain, both before and after a large flood (January 13, 1993). We also quantified the amount of these cover types within bands of the watershed 1 km wide × 5 km long directly upstream of each floodplain site. The amount of riparian vegetation destroyed by the flood within each section varied from nearly zero to almost 40% of pre‐flood coverage. The magnitude of loss in riparian vegetation was most strongly related to the amount of riparian vegetation initially present in the floodplain and the amount of urban surfaces in the nearby watershed. These results suggest that riparian vegetation within the San Luis Rey River floodplain is generally at high risk of destruction from large floods, and that this risk is exaggerated in areas with high urban development. We infer from these results that sites near existing large areas of intact riparian vegetation and away from urban development will have the highest potential for successful long‐term restoration.
Abnormal craniofacial development and expression patterns of extracellular matrix components in transgenic Del1 mice harboring a deletion mutation in the type II collagen gene
Authors: Savontaus M , Rintala‐Jämsä M , Morko J , Rönning O , Metsäranta M , Vuorio E 
Published: October 2004

Structured AbstractAuthors – Savontaus M, Rintala‐Jämsä M, Morka J, Rönning O, Metsäranta M, Vuorio EObjective – To analyze the effect of a type II collagen mutation on craniofacial development in transgenic Del1 mice.Design – Samples from homozygous (+/+) and heterozygous (+/−) transgenic Del1 mice harboring mutations in the type II collagen gene as well as non‐transgenic (−/−) littermates were collected at days 12.5, 14.5, 16.5 and 18.5 of gestation. The cartilaginous and bony elements of the craniofacial skeleton were analyzed after staining with alcian blue, alizarin red S and von Kossa. The expression patterns of type II, IX and X collagens and aggrecan were analyzed by immunohistochemistry and in situ hybridization.Results – Several abnormalities were observed in the craniofacial skeleton of transgenic Del1 mice. These include an overall retardation of chondrogenesis and osteogenesis in Del1 +/+ mice, and to a lesser extent also in Del1+/− mice. Characteristic findings in Del1 +/+ mice included a reduced anterioposterior length, a smaller size of the mandible, a palatal cleft and a downward bending snout. We also detected retarded ossification of calvarial bones in Del1 +/+ and +/− mice when compared with Del1 −/− mice. A surprising finding was the presence of both type II and X collagens and their mRNAs in the periosteum of the cranial base.Conclusion – The present study confirms the important role of type II collagen mutation in craniofacial development and growth. In addition to affecting endochondral ossification, the type II collagen mutation also disturbs intramembranous ossification in the developing craniofacial skeleton.
The efficacy of a fluoride varnish in reducing enamel demineralization adjacent to orthodontic brackets: an in vitro study
Authors: Demito CF , Vivaldi‐Rodrigues G , Ramos AL , Bowman SJ 
Published: October 2004

Structured AbstractAuthors – Demito CF, Vivaldi‐Rodrigues G, Ramos AL, Bowman SJObjectives – To test the hypothesis that fluoride varnish is effective in reducing demineralization (white spot) lesions adjacent to bonded orthodontic brackets.Design – Two similar samples of extracted bovine incisors, with bonded orthodontic brackets, were separated into an experimental group (fluoride varnish was applied) and control group (no fluoride varnish) to examine the preventive effects of fluoride varnish.Setting and Sample Population – The dental clinic of the State University of Maringá– UEM (Maringá, Paraná, Brazil). Thirty‐eight extracted bovine incisors with bonded orthodontic brackets.Experimental Variable – Fluoride varnish was applied topically to half of the sample of extracted bovine teeth. No varnish was applied to the other half.Outcome Measure – The depths of enamel demineralization (white spot) lesions were measured from polarized light microscopy images using image analysis software.Results – The teeth in both the experimental and control groups had been exposed to a cariogenic environment twice a day for 35 days. Those teeth that had been treated with two applications of fluoride varnish (one at the outset and another 15 days later) demonstrated about 38% less mean lesion depth than teeth where no varnish had been applied.Conclusion – Orthodontists may wish to consider the application of fluoride varnish during fixed orthodontic therapy to help reduce the development of enamel white spot lesions.
Polycarbonate Microfoams with a Smooth Surface and Higher Notched Impact Strength
Authors: Bledzki Andrzej K. , Kirschling Hendrik , Steinbichler Georg , Egger Peter 
Published: October 2004

Polycarbonate microfoams produced by physical blowing agents usually have an unacceptable surface quality. The surface is rough and the visual difference in the surface quality is striking. However, the surface quality can be improved by the gas counterpressure technology. Polycarbonate has a high elongation at break but a low notched impact strength. Earlier, the microfoams showed higher notched impact strength, but a considerably reduced elongation at break. Foams produced by the gas counter-pressure technology have both these positive mechanical properties.
Damage Analysis in Sandwich Beams with Cellular Core using Micromechanics Coupled to a Statistical Approach
Authors: Meraghni F. , Desrumaux F. , Benzeggagh M. L. 
Published: October 2004

This paper deals with the analysis of damage and mechanical properties of sandwich beams. The face sheets consist of glass mat-reinforced polyester (GMRP) perfectly bonded to core material. The latter is a regular array of thermoplastic tubular cells called Tubulam®. Mechanical behaviour of sandwich beams is analysed and simulated under three and four-point bending and correlated to experimental results. Sandwich beam modelling was performed according to two steps. First, skins behaviour is modelled by a micromechanical approach based upon the generalised Mori and Tanaka theory. Moreover, in the second step, an analytical model based on the laminate theory predicts the overall properties of core material. In this work, damage mechanisms are introduced in the modelling using probabilistic concepts applied at the microscopic scale of face sheets (fibres, matrix, interface between fibres and matrix) as well as at the mesoscopic scale namely tubular core and bond layer between core and skins. Finally, the developed model is validated by experimental tests: three and four-point bending. Experimentally measured global responses of the sandwich beams are compared to those numerically simulated and discussed in terms of damage chronology and evolution. The main point of the developed analysis is that the mechanical behaviour may be predicted on the basis of the structural parameters. Hence, it may provide an important analytical tool for aided design to optimise sandwich structures with respect to applied loading and micromechanical parameters.
Elevated levels of matrix metalloprotein-3 in patients with coronary aneurysm: A case control study
Authors: Tengiz Istemihan , Ercan Ertugrul , Aliyev Emil , Sekuri Cevad , Duman Can , Altuglu Imre 
Published: October 2004

Abstract
Background
Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of arterial aneurysms through increased proteolysis of extracellular matrix proteins. Increased proteolysis due to elevated matrix degrading enzyme activity in the arterial wall may act as a susceptibility factor for the development of coronary aneurysms. The aim of this study was to investigate the association between MMPs and presence of coronary aneurysms.

Methods
Thirty patients with aneurysmal coronary artery disease and stable angina were enrolled into study (Group 1). Fourteen coronary artery disease patients with stable angina were selected as control group (Group 2). MMP-1, MMP-3 and C-reactive protein (CRP) were measured in peripheral venous blood and matched between the groups.

Results
Serum MMP-3 level was higher in patients with aneurismal coronary artery disease compared to the control group (20.23 ± 14.68 vs 11.45 ± 6.55 ng/ml, p = 0.039). Serum MMP-1 (13.63 ± 7.73 vs 12.15 ± 6.27 ng/ml, p = 0.52) and CRP levels (4.78 ± 1.47 vs 4.05 ± 1.53 mg/l, p = 0.13) were not significantly different between the groups.

Conclusion
MMPs can cause arterial wall destruction. MMP-3 may play role in the pathogenesis of coronary aneurysm development through increased proteolysis of extracellular matrix proteins.