bluuebunny/crossref_metadata_2025 huggingface dataset:
THE WAGE–WAGE‐ . . . ‐WAGE–PROFIT RELATION IN A MULTISECTOR BARGAINING ECONOMY
Authors: Julius A. J.
Published: April 2009

The equalization of profit rates across industries subject to firm‐level bargaining over wages generates an interindustry wage structure with higher wages in capital‐intensive sectors. The familiar inverse wage–profit relation gives way to a wage–wage‐ . . . ‐wage–profit surface on which the profit rate can vary directly with the wage paid in an individual industry. Institutional changes that decrease workers' bargaining power and increase the incomes of the unemployed tend to compress the wage distribution; these changes draw political support from cross‐class coalitions of low‐wage workers and capital‐intensive firms. Some capital‐using, labor‐saving technical changes that raise capitalists' profits in current prices lower the equilibrium profit rate.
COMPETITION IN PRODUCT DESIGN: AN EXPERIMENT EXPLORING INNOVATION BEHAVIOR
Authors: Cantner Uwe , Güth Werner , Nicklisch Andreas , Weiland Torsten
Published: April 2009

We experimentally investigate competition for innovations in a patent race scenario. Pairs of subjects compete as seller firms on a duopoly market, investing in risky search. Successful innovations resulting thereof are rewarded via temporary monopoly rents. Classifying investor types reveals that most of them invest according to objective investment criteria, such as probability of search success and cash flow, as well as to non‐pecuniary criteria, such as intensity of competition and relative performance. For a minority, however, no such correlation is ascertained.
SCHLEIERMACHERIAN TRANSCENDENTAL SPIRITUALITY AND THE BOOK OF JOB
Authors: TURNBLOOM DAVID J.
Published: April 2009

The Book of Job is certainly one of the most enigmatic and attractive books in all of the Hebrew Scriptures. As a masterfully written poem, Job utilizes imagery and metaphor in such a way as to leave even the secular reader in awe. It tells the story of a pious man who, through many sufferings, is tested by the Divine and sent on a spiritual journey which culminates in a face to face meeting with God. As a poem and as Scripture, Job has been the subject many interpretations over thousands of years. Often read as an insight into the mysteries of evil, innocent suffering, human nature, and the Divine, this piece of poetic Scripture has been the source of much debate and frustration among scholars and the faithful alike. It is not the purpose of this essay to attempt an overview of these various interpretations with the intention of settling upon one superior interpretation. Also, it is not the purpose of this essay to refute any previous interpretations. What I will offer is merely one interpretation among many – an interpretation which I hope might further, if only to the smallest degree, the significance of this great text for even one reader.

This essay will take the theology of Friedrich Schleiermacher and, relying on an interpretation of Job given by Gustavo Gutierrez, offer a way of reading Job which leads to a transcendental spirituality. I will accomplish this in three parts: first, I will lay out certain Schleiermacherian concepts which advocate a form of transcendental spirituality; next, relying on Gutierrez's interpretation, I will draw parallels between Schleiermacher's concepts and the spiritual journey of Job; finally, I will show how the book of Job itself can be read as a tool for developing a transcendental spirituality within the reader. In the end, it will be clear that, without fear of ‘misinterpretation,’ the Book of Job can guide the reader to a transcendental spirituality.
Legal Tenure Security, Perceived Tenure Security and Housing Improvement in Buenos Aires: An Attempt towards Integration
Authors: VAN GELDER JEAN‐LOUIS
Published: April 2009

This article critically reviews several claims underlying different positions in the debate on tenure legalization and empirically investigates them in a low‐income settlement in Buenos Aires, Argentina. Even though both tenure legality, in the form of property titles, and perceived tenure security have separately been shown to influence housing improvement, most research has taken a relatively rudimentary approach to their measurement, and little work has been done to examine their interrelations. These issues are taken up in the present article in which the legal–illegal tenure dichotomy embedded in standard perspectives on legalization is broadened to include intermediate levels of legality and subsequently linked to a social psychological perspective on perceived tenure security. The question of to what extent property titles facilitate access to credit is also examined. The results show that tenure legality and perceived tenure security are in fact closely related in the settlement under study, as higher levels of legality also imply higher perceived tenure security. Furthermore, both tenure legality and perceived tenure security are significant predictors of housing improvement and, consequently, settlement development. There was, however, no relation between tenure legality and access to credit.

Cet article porte un œil critique sur plusieurs affirmations à la base d’opinions diverses dans le débat sur la légalisation du statut d’occupation, et les étudie de façon empirique dans le cas d’une implantation pour faibles revenus située à Buenos Aires. Même si on a montré indépendamment que la légalité de l’occupation, sous la forme de titres de propriété, et le sentiment de sécurité d’occupation ont influé sur l’amélioration des logements, la démarche adoptée pour mesurer ces deux aspects est restée relativement rudimentaire dans la plupart des recherches, l’examen de leurs interdépendances étant très largement ignoré. Ces aspects sont abordés ici en élargissant la dichotomie entre statut d’occupation légal‐illégal habituellement ancrée dans les points de vue sur la légalisation, afin d’inclure des niveaux intermédiaires de légalité, puis en l’associant à une perspective sociale psychologique sur le sentiment de sécurité d’occupation. Est aussi examinée la mesure dans laquelle la détention de titres de propriété facilite l’accès au crédit. Il en résulte que légalité et sentiment de sécurité d’occupation sont en fait étroitement liés dans l’habitat étudié, puisque des degrés de légalitéélevés impliquent un sentiment plus fort d’occupation sécurisée. En outre, légalité et sentiment de sécurité d’occupation sont deux indices importants d’amélioration de l’habitat et, par conséquent, d’aménagement du quartier. Toutefois, il n’est apparu aucun lien entre légalité d’occupation et accès au crédit.
Immigration as Local Politics: Re‐Bordering Immigration and Multiculturalism through Deterrence and Incapacitation
Authors: GILBERT LIETTE
Published: April 2009

Small town governments in North America have, in recent years, posed the most aggressive challenge to national immigration policy and multiculturalism. Immigration‐related municipal ordinances were introduced by local officials to defend the rights of local residents from the adverse effects of (unauthorized) immigration. Municipal measures proposed to control im/migrants not only present a constitutional challenge to the federal pre‐emption in matters of immigration law (which ineptitude they purport to redress), they expand on what Didier Bigo called a ‘governmentality of unease’, where migration is increasingly rationalized as a security problem. Municipal measures are re‐bordering the inclusion/exclusion of (unauthorized) migrants by expanding the territorial and political rationality of immigration control from the border to the interior, and by imposing and dispersing new mechanisms of control into the everyday spaces and practices of im/migrants regarded as ‘illegal’ and undesirable. This article examines two immigration‐related municipal measures (Hazleton, PA and Hérouxville, QC) which impose a logic of immigration control and identity protection through deterrence and incapacitation strategies, and thus erode civil rights of im/migrants.

Certaines petites municipalités nord‐américaines ont récemment bousculé les politiques d'immigration nationales et le multiculturalisme. Les autorités locales en question ont fait voter des arrêtés municipaux liés à l'immigration afin de défendre les droits de leurs concitoyens contre les perceptions néfastes de l'immigration (irrégulière). Tout en représentant un défi constitutionnel à l'égard de la préemption fédérale en matière de législation sur l'immigration (dont l'inadéquation est censée être corrigée), les propositions municipales de contrôler les (im)migrants prolongent ce que Didier Bigo a appelé une ‘gouvernementalité du malaise’ qui voit de plus en plus la migration comme un problème de sécurité. Les mesures municipales redessinent les limites de l'inclusion‐exclusion des migrants (irréguliers) en amenant, de la frontière jusqu'à l'intérieur, la logique territoriale et politique propre au contrôle de l'immigration, tout en imposant et en diffusant de nouveaux mécanismes de contrôle dans les pratiques et espaces quotidiens des (im)migrants jugés ‘illégaux’ et indésirables. L'article étudie deux mesures municipales liées à l'immigration (à Hazleton en Pennsylvanie et à Hérouxville au Québec), lesquelles dictent une logique de contrôle de l'immigration et de protection identitaire au travers de stratégies de dissuasion et de création d'incapacités; ce faisant, ces dispositions amoindrissent les droits civils des (im)migrants.
The Niche City Idea: How a Declining Manufacturing Center Exploited the Opportunities of Globalization
Authors: SCHLICHTMAN JOHN JOE
Published: April 2009

This article examines a small city that forged a global service industry niche. Its leaders aligned the temporality of its historic downtown with that of the international furniture industry to make it the world's primary furniture merchandising node. This article overviews the radical transformation of the downtown, describes the ‘choreography’ of the area, and considers what the author feels are the important wider implications of what is, on the surface, a deceptively odd case. The author suggests that, in engaging this specific strategy, this very unique city portends a more general type of post‐industrialNiche City, a city that forges global centrality by creating an economic specialization in a specific segment of the global service economy.

La petite ville qui intéresse cet article a créé une niche dans le secteur international du service. Ses dirigeants ont mis en adéquation la temporalité de son centre historique et celle de l’industrie internationale du meuble pour en faire la principale plate‐forme de marchandisation de ces produits. L’article présente la transformation radicale subie par le centre‐ville, dépeint la "chorégraphie" de la région et s’attache aux aspects qui constituent, pour l’auteur, les grandes implications de ce qu’on pourrait considérer, à première vue, comme un cas particulier. En adoptant cette stratégie singulière, cette ville tout à fait unique annonce un type plus généralisé de ville‐niche post‐industrielle, c’est‐à‐dire une ville qui fabrique une polarité mondiale en créant une spécialisation économique sur un segment particulier du marché international de l’économie de service.
Reason in the City? Communicative Action, Media and Urban Politics
Authors: BRIDGE GARY
Published: April 2009

From a pragmatist perspective this essay suggests how media practices as transactions (in terms of content, emotion, aesthetic power and in relation to everyday practices) might contribute to a dispersed form of communicative rationality which has implications for understanding urban democracy.

D'un point de vue pragmatiste, ce texte indique comment les pratiques des médias en tant que transactions (en termes de contenu, d'émotion, de force esthétique et par rapport aux pratiques quotidiennes) pourraient participer à une forme dispersée de rationalité des communications ayant des implications sur la compréhension de la démocratie urbaine.
The City versus the Media? Mapping the Mobile Geographies of Public Address
Authors: IVESON KURT
Published: April 2009

Frequently, efforts to establish the city's significance for the public sphere frame the city in opposition to the media. The city is imagined as a space of unmediated and co‐present publicness, while the media is imagined as a space of mediated and distantiated publicness. This essay argues against such an opposition. In place of it, the essay outlines an approach to the urban dimensions of public address which emphasizes the interaction of urban and media spaces and the mobility of public address. This approach is illustrated through a brief consideration of contestation over the governance of urban space in Sydney during the 2007 APEC Meeting.

Les tentatives visant à déterminer l'importance de la ville dans la sphère publique conçoivent souvent la ville en opposition aux médias. La ville est imaginée comme un espace dont la nature publique est proche et non médiatisée, tandis que les médias sont imaginés en tant qu'espace dont la nature publique est distante et médiatisée. L'argument de l'auteur combat cette opposition. Il présente une approche des dimensions urbaines de la communication publique qui met en évidence l'interaction des espaces urbains et médiatisés ainsi que la mobilité de la communication publique. Cette approche est illustrée par une courte étude de la contestation soulevée par la gouvernance de l'espace urbain à Sydney lors du Sommet de l'APEC en 2007.
Mediating Urban Politics
Authors: RODGERS SCOTT , BARNETT CLIVE , COCHRANE ALLAN
Published: April 2009

Despite the turn to relational vocabularies in urban theory, most work on urban politics acknowledging the importance of media has tended to reproduce a centred image of ‘the media’ and a functionalist account of mediation. This essay suggests, by contrast, that media might be understood more phenomenologically, as those technologies embedded in the dispersed practices of urban life, and as assemblages of integrative practices (i.e. ‘the media’), both of which identify and subject to action a range of issues that are problematized as ‘urban’. Such a focus on media‐in‐practices is an important shift in perspective for research hoping to bring together the shared political concerns of urban and media studies, and to take advantage of the converging spatial imaginations and reconfigured understandings of mediation emerging across both fields.

Même si la théorie urbaine a adopté une terminologie du relationnel, la plupart des travaux de politique urbaine qui admettent l'importance des médias reproduisent plutôt une image centrifuge des ‘médias’ et une explication fonctionnaliste de la médiation. Ce texte suggère a contrario que l'on peut appréhender les médias sur un plan plus phénoménologique, en les considérant comme les technologies intégrées aux pratiques dispersées de la vie urbaine et comme des combinaisons de pratiques permettant l'agrégation (autrement dit, des ‘médias’), les deux aspects définissant, et exposant à une action, toute une série de problèmes qualifiés d'urbains. Un tel intérêt pour ‘les médias dans leurs pratiques’ constitue un important revirement de point de vue pour les recherches qui espèrent réunir les préoccupations politiques communes des études urbaines et des études sur les médias, tout en exploitant la convergence des imaginaires spatiaux et les reformulations de la médiation qui apparaissent dans les deux domaines.
Artists, Tourists, and the State: Cultural Tourism and the Flamenco Industry in Andalusia, Spain
Authors: AOYAMA YUKO
Published: April 2009

In this article, I seek to demonstrate how research on cultural industries and tourism combined yields insights into the contemporary dynamics of cultural survival in the age of globalization. Tourism is increasingly an important economic force that facilitates cultural mobility and promotes cultural consumption, and in turn contributes to the growth of a regionally embedded cultural industry. I take the example of flamenco music and dance in southern Spain and focus on three agents that help shape this art complex — the cultural industry, the tourists and the state. I analyze how these agents interact, and show how their engagements at multiple geographic scales result in a distinctive and successful cultural tourism in Seville, Andalusia. The flamenco art complex survives and thrives today through the combination of resilient local talent closely linked to identity maintenance, domestic and foreign tourists that engage in cultural consumption, and the government subsidizing the artists through state‐sponsored spectacles.

Ce travail montre comment la recherche sur les industries culturelles et le tourisme combinés peut apporter des perspectives sur les dynamiques contemporaines de survie culturelle à l'ère de la mondialisation. Le tourisme devient une force économique considérable qui facilite la mobilité culturelle et favorise la consommation culturelle, ce qui contribue à la croissance d'une industrie culturelle inscrite au plan régional. Prenant le cas de la musique et de la danse flamenco dans le sud de l'Espagne, l'article s'intéresse à trois agents qui participent à la conformation de ce complexe artistique : l'industrie culturelle, les touristes et l'État. Il analyse les modalités d'interaction entre ces agents, et montre comment l'engagement de ceux‐ci à plusieurs échelons géographiques se traduit par un tourisme culturel spécifique et couronné de succès à Séville, en Andalousie. Le complexe artistique du flamenco subsiste et prospère aujourd'hui grâce à un talent local vivace, étroitement liéà la préservation d'une identité, alliéà des touristes nationaux et étrangers qui prennent part à la consommation culturelle, ainsi qu'au gouvernement qui finance les artistes à travers des spectacles subventionnés par l'État.
Spatial and temporal patterns in the diet of the Andean condor: ecological replacement of native fauna by exotic species
Authors: Lambertucci S. A. , Trejo A. , Di Martino S. , Sánchez‐Zapata J. A. , Donázar J. A. , Hiraldo F.
Published: April 2009

The development of conservation strategies to protect viable populations of scavenging birds requires the existence of adequate and safe food supplies in the wild. Early reports on Andean condors Vultur gryphus diet recorded guanacos and rheas, the dominant herbivores since the Pleistocene, as their main food in Patagonia. However, in the past century, guanaco and rhea populations have notably decreased as a consequence of introduced livestock, and other exotic mammals have colonized the region. We study the spatial and temporal variation of the condors' diet to determine which species are being consumed by condors, and to test whether native herbivores still have a role as a food source. We analysed 371 pellets (517 prey items), collected along 500 km in northwestern Patagonia, Argentina. Our study shows that the Andean condor depends heavily (98.5%) on exotic herbivores. Their diet was made up of c. 51% sheep/goat, 24% hare/rabbit, 17% red deer and 6% cow/horse, with only 2% other mammal species. Samples from locations surveyed after 12–15 years showed a diet shift coincident with the local tendencies in the food source. The diet composition of condors using roosts within the same zone was very similar, which suggests that they may be feeding from the same area. Thus, unhealthy carcasses could impact the entire local populations. Our results show the abundance of the invasive species in northwestern Patagonia and support the idea that native mega‐herbivores are ecologically extinct in this area. Exotic species management can have a decisive impact on scavenger's survival. It is necessary to apply a strategy that includes public environmental education about the problems of scavengers (e.g. use of poison, veterinary medicines and lead bullets), and a serious productive plan, including native species as a suitable source of economic development.
Maternal anthropometrics are associated with fetal size in different periods of pregnancy and at birth. The Generation R Study
Authors: Ay L , Kruithof CJ , Bakker R , Steegers EAP , Witteman JCM , Moll HA , Hofman A , Mackenbach JP , Hokken‐Koelega ACS , Jaddoe VWV
Published: April 2009

Objective  We aimed to examine the associations of maternal anthropometrics with fetal weight measured in different periods of pregnancy and with birth outcomes.

Design  Population‐based birth cohort study.

Setting  Data of pregnant women and their children in Rotterdam, the Netherlands.

Population  In 8541 mothers, height, prepregnancy body mass index (BMI) and gestational weight gain were available.

Methods  Fetal growth was measured by ultrasound in mid‐ and late pregnancy. Regression analyses were used to assess the impact of maternal anthropometrics on fetal weight and birth outcomes.

Main outcome measures  Fetal weight and birth outcomes: weight (grams) and the risks of small (<5th percentile) and large (>95th percentile) size for gestational age at birth.

Results  Maternal BMI in pregnancy was positively associated with estimated fetal weight during pregnancy. The effect estimates increased with advancing gestational age. All maternal anthropometrics were positively associated with fetal size (P‐values for trend <0.01). Mothers with both their prepregnancy BMI and gestational weight gain quartile in the lowest and highest quartiles showed the highest risks of having a small and large size for gestational age child at birth, respectively. The effect of prepregnancy BMI was strongly modified by gestational weight gain.

Conclusions  Fetal growth is positively affected by maternal BMI during pregnancy. Maternal height, prepregnancy BMI and gestational weight gain are all associated with increased risks of small and large size for gestational age at birth in the offspring, with an increased effect when combined.
The clinical relevance of hysteroscopic polypectomy in premenopausal women with abnormal uterine bleeding
Authors: van Dongen H , Janssen CAH , Smeets MJGH , Emanuel MH , Jansen FW
Published: April 2009

This study assessed the efficacy of hysteroscopic polyp removal in the management of abnormal uterine bleeding (AUB) of premenopausal patients. The monthly menstrual blood loss, measured semi‐objectively by the pictorial blood loss assessment chart (PBAC) and patients satisfaction were recorded prospectively preoperatively and postoperatively. Twenty‐one patients were included. Median monthly PBAC‐score before treatment was 288 (range 142–670) and 6 months after polyp removal 155 (range 39–560). It was concluded that hysteroscopic polyp removal in premenopausal women with AUB reduces the monthly blood loss significantly and has a high satisfaction rate on the short term.
Lymphovascular space involvement in early stage well‐differentiated endometrial cancer is associated with increased mortality
Authors: O’Brien DJ , Flannelly G , Mooney EE , Foley M
Published: April 2009

Objective  To study the relationship between lymphovascular space involvement (LVSI) in stage 1a or 1b well‐differentiated endometrial cancer and survival.

Design  Retrospective study consisting of a search of an oncology database to identify women with endometrial cancer between January 1990 and December 2004.

Setting  Tertiary referral centre, Dublin, Ireland.

Sample  Women who had well‐differentiated stage 1a or 1b endometrial cancer.

Methods  During the period 1990–2004, 226 patients with endometrial cancer were treated in the National Maternity Hospital, Dublin. We looked at all patients who had well‐differentiated endometrioid adenocarcinoma of the endometrium with invasion of <50% thickness of the myometrium. Forty‐one patients fulfilled these inclusion criteria. The presence or absence of LSVI was determined by review of haematoxylin and eosin sections. Patients were followed for 5 years or till death if earlier. Mortality was calculated. Statistical analysis was performed using Fisher’s exact test. An odds ratio and 95% confidence interval was calculated using fixed effect Mantel–Haenszel model.

Main outcome measures  Death from recurrence of endometrial cancer.

Results  Of the 41 patients, five (12%) were found to have (LVSI). Of the five patients with LVSI, three (60%) patients died of recurrence. All patients with recurrence died of disease and none of the patients without LVSI died (0 of 36). Overall, the survival rate was 92.7%. The presence of LVSI was a highly significant predictor of recurrence (P < 0.001).

Conclusion  In patients with early stage well‐differentiated adenocarcinoma of the endometrium, the presence of LVSI is associated with a high risk of death.
Radiofrequency ablation of retained placenta accreta after conservative management: preliminary evaluation in the pregnant ewe and in normal human placenta in vitro
Authors: Morel O , Monceau E , Tran N , Malartic C , Morel F , Barranger E , Côté JF , Gayat E , Chavatte‐Palmer P , Cabrol D , Tsatsaris V
Published: April 2009

Objective  To evaluate radiofrequency (RF) efficiency and safety for the ablation of retained placenta in humans, using a pregnant sheep model.

Design  Experimental study.

Setting  Laboratory of Surgery School, Nancy, France.

Population/sample  Three pregnant ewes/ten human placentas.

Methods  Various RF procedures were tested in pregnant ewes on 50 placentomes (individual placental units). Reproducibility of the best procedure was then evaluated in a further 20 placentomes and on ten human term placentas in vitro after delivery.

Main outcome measures  Placental tissues destruction, lesions’ size, myometrial lesions.

Results  Low power (100 W) and low target temperatures (60°C) lead to homogenous tissue destruction, without myometrial lesion. No significant difference was observed in terms of lesion size and procedure duration for in the placentomes of pregnant ewe in vivo and in human placentas in vitro. The diameter of the ablation could be correlated with the tines deployment.

Conclusion  The placental tissue structure is very permissive to RF energy, which suggests that RF could be used for the ablation of retained placenta, providing optimal control of tissue destruction. These results call for further experimental evaluations.
Why remove all cervical polyps and examine them histologically?
Authors: MacKenzie IZ , Naish C , Rees CMP , Manek S
Published: April 2009

A retrospective analysis of 1366 cervical polyps showed that none had malignant features and 67% were removed from asymptomatic women. A policy removing only cervical polyps from symptomatic women or those with abnormal cervical cytology and limiting histological examination to these polyps would result in significant savings and reduce the small risk of morbidity associated with polypectomy.
Perinatal mortality and morbidity in a nationwide cohort of 529 688 low‐risk planned home and hospital births
Authors: de Jonge A , van der Goes BY , Ravelli ACJ , Amelink‐Verburg MP , Mol BW , Nijhuis JG , Gravenhorst J Bennebroek , Buitendijk SE
Published: April 2009

Objective  To compare perinatal mortality and severe perinatal morbidity between planned home and planned hospital births, among low‐risk women who started their labour in primary care.

Design  A nationwide cohort study.

Setting  The entire Netherlands.

Population  A total of 529 688 low‐risk women who were in primary midwife‐led care at the onset of labour. Of these, 321 307 (60.7%) intended to give birth at home, 163 261 (30.8%) planned to give birth in hospital and for 45 120 (8.5%), the intended place of birth was unknown.

Methods  Analysis of national perinatal and neonatal registration data, over a period of 7 years. Logistic regression analysis was used to control for differences in baseline characteristics.

Main outcome measures  Intrapartum death, intrapartum and neonatal death within 24 hours after birth, intrapartum and neonatal death within 7 days and neonatal admission to an intensive care unit.

Results  No significant differences were found between planned home and planned hospital birth (adjusted relative risks and 95% confidence intervals: intrapartum death 0.97 (0.69 to 1.37), intrapartum death and neonatal death during the first 24 hours 1.02 (0.77 to 1.36), intrapartum death and neonatal death up to 7 days 1.00 (0.78 to 1.27), admission to neonatal intensive care unit 1.00 (0.86 to 1.16).

Conclusions  This study shows that planning a home birth does not increase the risks of perinatal mortality and severe perinatal morbidity among low‐risk women, provided the maternity care system facilitates this choice through the availability of well‐trained midwives and through a good transportation and referral system.
The statistics of refractive error maps: managing wavefront aberration analysis without Zernike polynomials
Authors: Iskander D. Robert , Nam Jayoung , Thibos Larry N.
Published: April 2009

The refractive error of a human eye varies across the pupil and therefore may be treated as a random variable. The probability distribution of this random variable provides a means for assessing the main refractive properties of the eye without the necessity of traditional functional representation of wavefront aberrations. To demonstrate this approach, the statistical properties of refractive error maps are investigated. Closed‐form expressions are derived for the probability density function (PDF) and its statistical moments for the general case of rotationally‐symmetric aberrations. A closed‐form expression for a PDF for a general non‐rotationally symmetric wavefront aberration is difficult to derive. However, for specific cases, such as astigmatism, a closed‐form expression of the PDF can be obtained. Further, interpretation of the distribution of the refractive error map as well as its moments is provided for a range of wavefront aberrations measured in real eyes. These are evaluated using a kernel density and sample moments estimators. It is concluded that the refractive error domain allows non‐functional analysis of wavefront aberrations based on simple statistics in the form of its sample moments. Clinicians may find this approach to wavefront analysis easier to interpret due to the clinical familiarity and intuitive appeal of refractive error maps.
Limits of spherical blur determined with an adaptive optics mirror
Authors: Atchison David A. , Guo Huanqing , Fisher Scott W.
Published: April 2009

We extended an earlier study (Vision Research, 45, 1967–1974, 2005) in which we investigated limits at which induced blur of letter targets becomes noticeable, troublesome and objectionable. Here we used a deformable adaptive optics mirror to vary spherical defocus for conditions of a white background with correction of astigmatism; a white background with reduction of all aberrations other than defocus; and a monochromatic background with reduction of all aberrations other than defocus. We used seven cyclopleged subjects, lines of three high‐contrast letters as targets, 3–6 mm artificial pupils, and 0.1–0.6 logMAR letter sizes. Subjects used a method of adjustment to control the defocus component of the mirror to set the ‘just noticeable’, ‘just troublesome’ and ‘just objectionable’ defocus levels. For the white‐no adaptive optics condition combined with 0.1 logMAR letter size, mean ‘noticeable’ blur limits were ±0.30, ±0.24 and ±0.23 D at 3, 4 and 6 mm pupils, respectively. White‐adaptive optics and monochromatic‐adaptive optics conditions reduced blur limits by 8% and 20%, respectively. Increasing pupil size from 3–6 mm decreased blur limits by 29%, and increasing letter size increased blur limits by 79%. Ratios of troublesome to noticeable, and of objectionable to noticeable, blur limits were 1.9 and 2.7 times, respectively. The study shows that the deformable mirror can be used to vary defocus in vision experiments. Overall, the results of noticeable, troublesome and objectionable blur agreed well with those of the previous study. Attempting to reduce higher‐order aberrations or chromatic aberrations, reduced blur limits to only a small extent.
Comparison of high‐speed videokeratoscopy and ultrasound distance sensing for measuring the longitudinal corneal apex movements
Authors: Kowalska Malgorzata A. , Kasprzak Henryk T. , Robert Iskander D.
Published: April 2009

Two different methods to measure binocular longitudinal corneal apex movements were synchronously applied. High‐speed videokeratoscopy at a sampling frequency of 15 Hz and a custom‐designed ultrasound distance sensor at 100 Hz were used for the left and the right eye, respectively. Four healthy subjects participated in the study. Simultaneously, cardiac electric cycle (ECG) was registered for each subject at 100 Hz. Each measurement took 20 s. Subjects were asked to suppress blinking during the measurements. A rigid headrest and a bite‐bar were used to minimize undesirable head movements. Time, frequency and time‐frequency representations of the acquired signals were obtained to establish their temporal and spectral contents. Coherence analysis was used to estimate the correlation between the measured signals. The results showed close correlation between both corneal apex movements and the cardiopulmonary system. Unraveling these relationships could lead to better understanding of interactions between ocular biomechanics and vision. The advantages and disadvantages of the two methods in the context of measuring longitudinal movements of the corneal apex are outlined.
Changes of ocular aberrations with gaze
Authors: Prado P. , Arines J. , Bará S. , Manzanera S. , Mira‐Agudelo A. , Artal P.
Published: April 2009

The dependence of the ocular aberrations on gaze has been studied in three eyes using a fast‐acquisition, Hartmann–Shack wavefront sensor. Although there were some trends in the change of some aberration terms with gaze, the changes of most Zernike coefficients were smaller than their variability at each individual gaze position, due to the combined effects of microfluctuations of accommodation, eye movements, tear film dynamics, and measurement noise. For our particular experimental dataset, the confidence level at which the null hypothesis (i.e. that the aberrations do not change significantly with gaze) can be rejected is very low. Further advances in the study of the dependence of eye aberrations with gaze will require a tighter control of the sources of aberration variability at each individual gaze position.
Comparison of the ocular wavefront aberration between pharmacologically‐induced and stimulus‐driven accommodation
Authors: Plainis S. , Plevridi E. , Pallikaris I. G.
Published: April 2009

Purpose:  To compare the ocular wavefront aberration between pharmacologically‐ and stimulus‐driven accommodation in phakic eyes of young subjects.

Methods:  The aberration structure of the tested eye when accommodating was measured using the Complete Ophthalmic Analysis System (COAS; AMO WaveFront Sciences, Albuquerque, NM, USA). It was used in conjunction with a purposely‐modified Badal optometer to allow blur‐driven accommodation to be stimulated by a high contrast letter E with a vergence range between +0.84 D and −8.00 D. Pharmacological accommodation was induced with one drop of pilocarpine 4%. Data from six subjects (age range: 23–36 years) with dark irides were collected.

Results:  No correlation was found between the maximal levels of accommodative response achieved with an 8 D blur‐driven stimulus and pharmacological stimulation. Pharmacological accommodation varied considerably among subjects: maximum accommodation, achieved within 38–85 min following application of pilocarpine, ranged from 2.7 D to 10.0 D. Furthermore, although the changes of spherical aberation and coma as a function of accommodation were indistinguishable between the two methods for low levels of response, a characteristic break in the pattern of aberration occurred at higher levels of pilocarpine‐induced accommodation. This probably resulted from differences in the time course of biometric changes occuring with the two methods.

Conclusion:  Measuring the pilocarpine‐induced accommodative response at only one time point after its application may lead to misleading results. The considerable inter‐individual differences in the time course of drug‐induced accommodative response and its magnitude may lead to overestimation or underestimation of the corresponding amplitude of normal, blur‐driven accommodation. Stimulating accommodation by topical application of pilocarpine is inappropriate for evaluating the efficacy of ‘accommodating’ IOLs.
Myopia and visual acuity impairment: a comparative study of Greek and Bulgarian school children
Authors: Plainis Sotiris , Moschandreas Joanna , Nikolitsa Panagoula , Plevridi Eleani , Giannakopoulou Trisevgeni , Vitanova Vania , Tzatzala Paraskevi , Pallikaris Ioannis G. , Tsilimbaris Miltiadis K.
Published: April 2009

Purpose: To compare the proportions of school children with myopia and impaired visual acuity in Greece and Bulgaria.

Methods: A sample of 898 children, aged 10–15 years, was selected from two primary and two secondary schools in a Greek city (Heraklion), and one primary and secondary school in a Bulgarian city (Stara Zagora). Five hundred and eighty eight children were Greek (65.5%, mean age 12.5 ± 0.08 years) and 310 Bulgarian (34.5%, age 12.4 ± 0.07 years). VA was assessed with the habitual refractive correction. Refractive error was measured in the absence of cycloplegia using an auto‐refractor.

Results: The percentage of children, tested with their habitual refractive correction, with decimal VA <0.5 in at least one eye was 11.7% (95% CI 9.1–14.3%) for Greek and 5.2% (95% CI 2.7–7.6%) for Bulgarian pupils. The percentage of myopic children also differed between the two countries with the proportion with myopic refractive error ≤−0.75 D and decimal VA <0.8 at primary school level being 14.1% and 28.9% in Stara Zagora and Heraklion respectively and 13.0% and 46.9% (95% CI 18.2–29.2%,p < 0.0001) at secondary school level. Among the myopic pupils only 35.8% used corrective spectacles in Stara Zagora, compared to 70.7% of the children in Heraklion. Finally, myopia appeared more prevalent in female adolescents with the effect being statistically significant only for Greek children (55% vs 40% of males,p = 0.015).

Conclusions: The increased proportion of myopic children in Heraklion, compared to Stara Zagora, may arise from a number of environmental and socio‐economic factors, which need to be further investigated in order to understand the differences observed among European populations.
Contrast sensitivity based orientation changes in refractive surgery patients
Authors: Tahir Humza J. , Parry Neil R. A. , Brahma Arun , Ikram Khalid , Murray Ian J.
Published: April 2009

It is well known that refractive surgery leads to an increase in higher‐order aberrations. These can cause problems such as glare, starburst and halos in vision, particularly in low light levels when the pupil is large. The overall wavefront aberration of the eye is typically non‐circularly symmetric due to the presence of aberrations such as coma and trefoil. These asymmetries have been shown to induce orientation‐selective effects in grating‐based contrast sensitivity tests. Classically, contrast sensitivity is assumed to be independent of orientation and is measured at only one orientation. Examining more orientations may give a better indicator of visual performance when abnormal amounts of aberration are present. To examine this, contrast sensitivity through a dilated pupil was determined for four orientations of a 12 cycles deg−1 sine wave grating in 12 subjects both before and after refractive surgery. Surgery produced orientation‐selective changes in contrast sensitivity in most patients (9 out of 12, p < 0.05). The correlation between contrast sensitivity and higher‐order aberrations was found to improve when several orientations were tested compared with data from only one orientation (combined orientations, r2 = 0.46, p = 0.007; single orientation r2 = 0.55, p < 0 .05 to r2 = 0.09, p > 0.05). These results indicate that grating orientation is an important factor when investigating the link between visual performance and higher order aberrations.
Analysis of the optical properties of crystalline lenses by point‐diffraction interferometry
Authors: Acosta Eva , Vázquez Daniel , Castillo Luis Rodríguez
Published: April 2009

Purpose:  To show the feasibility of modified point‐diffraction interferometry for the qualitative analysis and accurate quantification of phase aberrations of eye lenses in vitro.

Method:  Optical aberrations of crystalline lenses in vitro were evaluated by means of a point‐diffraction interferometer modified to increase its dynamic range.

Results:  Analysis of the Zernike polynomials, , which contribute significantly to the wavefront aberration of two representative crystalline lenses (a mammalian and a fish lens) is presented. In the mammalian case, the in vitro experiments were performed for pig lenses. It is shown that spherical aberration, astigmatism, coma, and trefoil of different radial orders, n, are the only modes contributing significantly to wavefront aberration, i.e., aberrations with azimuthal frequencies, m, greater that three can be regarded as noise. In the case of fish lenses (sea bream), we show that the technique allows quantification of the deviation from the spherical symmetry which is commonly assumed for teleost fish lenses.

Conclusions:  Modified point‐diffraction interferometry is a wavefront‐sensing technique that can be used to accurately analyze phase aberrations in eye lenses and hence evaluate their contribution, in terms of significant aberrations, to the total aberrations of the eye.
Retinal image quality for virtual eyes generated by a statistical model of ocular wavefront aberrations
Authors: Thibos Larry N.
Published: April 2009

A statistical model of the aberration structure of normal, well‐corrected eyes was developed previously (Opthal. Physiol. Opt22, 427–433, 2002.) from wavefront aberrations measured for 100 normal eyes (J. Opt. Soc. Am. A.19, 2329–2348, 2002.). The model is capable of generating an unlimited number of wavefront aberration functions for virtual eyes drawn randomly from a multivariate Gaussian distribution of Zernike aberration coefficients. This report provides evidence that monochromatic retinal image quality in virtual eyes, as quantified by 31 different image quality metrics (J. Vis.4, 329–351, 2004.), is representative of human eyes but slightly exaggerates the degradation of the retinal image caused by ocular aberrations. A demonstration program for producing virtual eyes is included as an Appendix to this paper.
The contribution of the fixational eye movements to the variability of the measured ocular aberration
Authors: Arines J. , Pailos E. , Prado P. , Bará S.
Published: April 2009

The purpose of this work is to analyze the contribution of eye movements to the variability of the Zernike coefficients as determined with a Hartmann–Shack aberrometer. In order to isolate this effect we considered static aberrations tied to the eye pupil. We used several eye movements of different magnitude, both synthetic and corresponding to actual series recorded in our laboratory with different subjects. Our results show the relevance of the modal coupling induced by the estimation process and the benefit of correcting eye movements in order to get a better estimate of the ocular aberrations. They also show that eye movements during aberrometric measurements are an important source of apparent wavefront variability.
Damped least‐squares approach for point‐source corneal topography
Authors: Sokurenko Vyacheslav , Molebny Vasyl
Published: April 2009

An optimization algorithm to be used in point‐source corneal topographers is developed for the reconstruction of the topography of aspheric corneal surfaces. It is based on the damped least‐squares technique. The reconstructions obtained with a topographer comprising 48 or 90 point sources for corneas having different forms (spherical, conicoidal, complex) and apical radii (5–16 mm) were simulated numerically. Zernike polynomials up to the seventh radial order were used for the description of the shape of the anterior corneal surface. With no noise, i.e. uncertainty in the position of the image of each object point, it is shown that this approach allows reconstruction of the surface with a root‐mean‐square (RMS) error of <5 × 10−7 μm for the elevation map and 3 × 10−7 diopter for the refraction map. With noise, to get an averaged surface elevation RMS error of <1 μm, or an averaged refraction RMS error of <0.25 diopter, each spot must be located (in the image plane) with an error <1 μm.
Nasal‐temporal differences in cone‐opponency in the near peripheral retina
Authors: Panorgias A. , Parry N. R. A. , McKeefry D. J. , Kulikowski J. J. , Murray I. J.
Published: April 2009

The purpose of this study is to establish whether nasal‐temporal differences in cone photoreceptor distributions are linked to differences in colour matching performance in the two hemi‐fields. Perceived shifts in chromaticity were measured using an asymmetric matching paradigm. They were expressed in terms of hue rotations and relative saturation changes and also in terms of activation levels of L−M or S−(L+M) cone‐opponent channels. Up to 19° eccentricity there was little difference in chromaticity shifts between nasal and temporal retina for either channel. For matches beyond 19° L−M activation is significantly lower in the nasal field and the S−(L+M) channel was equally activated in both fields. The data are consistent with the asymmetric distribution of L‐ and M‐cones in the nasal and temporal retinae.
Macular pigment measurement in clinics: controlling the effect of the ageing media
Authors: Makridaki M. , Carden D. , Murray I. J.
Published: April 2009

We report a series of experiments designed to ensure that Macular Pigment Optical Density (MPOD) measurements obtained with a clinical instrument are not influenced by lens yellowing and ocular media optical density. These effects were determined in six subjects using seven Lee Colour Temperature Correcting filters to simulate changes in the transmittance of the ocular media with age. Calculated simulated age matched the data linking age and optical density reported in the literature, and the MPOD was independent of simulated age. The instrument allows an estimation of MPOD to be made which is based only on a foveal (centre‐only) measurement rather than, as is conventional, making a comparison between foveal and peripheral measurements. We assessed the performance of this facility by comparing the centre‐only estimate of MPOD with that obtained from both central and peripheral measurements in 5616 eyes. The 95% limits of agreement for the two estimates was 0.13 OD units.