Tight Lens Research Articles

On the existence of supporting broken book decompositions for contact forms in dimension 3

We prove that in dimension 3 every nondegenerate contact form is carried by a broken book decomposition. As an application we obtain that on a closed 3-manifold, every nondegenerate Reeb vector field has either two or infinitely many periodic orbits, and two periodic orbits are possible only on the tight sphere or on a tight lens space. Moreover we get that if M is a closed oriented 3-manifold that is not a graph manifold, for example a hyperbolic manifold, then every nondegenerate Reeb vector field on M has positive topological entropy.

On symplectic fillings of virtually overtwisted torus bundles

We use Menke's JSJ-type decomposition theorem for symplectic fillings to reduce the classification of strong and exact symplectic fillings of virtually overtwisted torus bundles to the same problem for tight lens spaces. For virtually overtwisted structures on elliptic or parabolic torus bundles, this gives a complete classification. For virtually overtwisted structures on hyperbolic torus bundles, we show that every strong or exact filling arises from a filling of a tight lens space via round symplectic 1-handle attachment, and we give a condition under which distinct tight lens space fillings yield the same torus bundle filling.

The Wings of Atalanta: Essays Written along the Color Line

The Wings of Atalanta: Essays Written along the Color Line

The Heromartyrs of Cyprus: National Museums as Greek Orthodox Hagiographical Media

ABSTRACTIn 1961, a “Museum of the Struggle” was created to remember and glorify the heroes of the Greek Cypriot anticolonial war (1955–1959). The museum functions, this article argues, as an apparatus of hagiographical mediation, rendering for local and international publics an aura of sanctification around the war’s fallen fighters. Such an impression is generated by the museum’s spatial mise-en-scène, its progressive orientation of visitors who move through its halls, its ways of curating belongings and images of the dead, its narrative construction of the life and conduct of the fighters, and its subtle evocation of traditional saintly patronage associated with the island’s communities. Drawing on original fieldwork in Cyprus between 2012 and 2018, the article treats the musealization of the Greek-Cypriot national struggle as a tight lens through which to consider the diversity of processes by which modern Orthodox Christians in (post)colonial situations construe, commemorate, and maintain relationships with holiness. In particular, it finds that the celebration of the dead anticolonial fighters as “heromartyrs” (ērōomartyres) serves to constitute a distinctive category of Christian martyrdom that infuses a post-Byzantine martyriological identity with the imagination of ancient Greek heroic virtue and epic violence.

Global surfaces of section for dynamically convex Reeb flows on lens spaces

We show that a dynamically convex Reeb flow on the standard tight lens space ( L ( p , 1 ) , ξ s t d ) (L(p, 1),\xi _\mathrm {std}) , p > 1 , p>1, admits a p p -unknotted closed Reeb orbit P P which is the binding of a rational open book decomposition with disk-like pages. Each page is a rational global surface of section for the Reeb flow and the Conley-Zehnder index of the p p th iterate of P P is 3 3 . We also check dynamical convexity in the Hénon-Heiles system for low positive energies. In this case the rational open book decomposition follows from the fact that the sphere-like component of the energy surface admits a Z 3 \mathbb {Z}_3 -symmetric periodic orbit and the flow descends to a Reeb flow on the standard tight ( L ( 3 , 2 ) , ξ s t d ) (L(3,2),\xi _\mathrm {std}) .

ЭДВАРДИАНСКИЙ КОД В АНГЛИЙСКОЙ ПРОЗЕ ХХI ВЕКА

The article considers the references of modern authors to the traditions of Edwardianism. This period can be characterized as a vibrant cultural era, with writers who were determined to break away from the stifling influence of preceding Victorian literature and provided the cultural foundation for the coming century. The ‘Edwardian code’ fully developed in literature of the interwar decades (1920s–1930s) and revived in the early 21 st century. It includes such elements as the image of the manor house, the motifs of Arts & Crafts movement, the theme of childhood and associated themes of the English fairy tale, which went through its ‘golden age’ in the abovenamed period. The code also comprises motifs of social change and other related issues. All parts of the Edwardian code are found in A. Byatt’s novel Childhood`s Book (2009). The novel covers the period from 1895 to the end of the Great War. It represents a tangle of many fates, each of which is concerned with the conflicts of the era and the general atmosphere of the Edwardian time. The characters are united by the desire to formulate a clear goal of their existence and specific personal qualities determined by the artistry of the era. In the 21st century, the ‘Edwardian code’ is found in non-fiction literature, in TV series and in the aspiration of the national consciousness to the value orientations of Edwardianism. A typical example is J. Nicolson’s The Perfect Summer: England 1911, Just Before the Storm (2008). The Perfect Summer chronicles a glorious English summer a century ago, when the world was on the cusp of irrevocable change. Through the tight lens of four months, Juliet Nicolson’s rich storytelling gift rivets us with the sights, colors, and feelings of the bygone era. This book is a vividly rendered glimpse of the twilight of the Edwardian era. The commercial success of the novels with the Edwardian code reflects the interest of the reading public to it. The goal-setting required in this code and its distinct axiology evidence the over­coming of postmodern moral relativism. The author of the paper makes an assumption about the formation of ‘Neo-Edwardianism’ in the modern culture of Great Britain.

A dynamical characterization of universally tight lens spaces

We give necessary and sufficient conditions for a closed connected co-orientable contact $3$-manifold $(M,\xi)$ to be a standard lens space based on assumptions on the Reeb flow associated to a defining contact form. Our methods also provide rational global surfaces of section for nondegenerate Reeb flows on $(L(p,q),\xi_{\rm std})$ with prescribed binding orbits.

CONSTRAINING SOURCE REDSHIFT DISTRIBUTIONS WITH GRAVITATIONAL LENSING

We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that ~40 massive ($\sigma_v=1200$ km/s) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to ~11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as $N_{lens}^0.5$, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

Silicon photodiodes for low-voltage electron detection in scanning electron microscopy and electron beam lithography

Silicon photodiode (SPD) detectors can be used for secondary electron detection in miniature electron beam columns, where small apertures, tight lens spacings, and short working distances make traditional detectors impractical. Monte Carlo simulations presented in this article suggest that in these configurations, SPDs have an advantage over traditional secondary electron detectors due to their potentially higher collection efficiency. Responsivity results presented here for SPDs with 40 and 60Å passivation layers show measurable responsivity for electron energies down to 80eV. High contrast images obtained using a SPD mounted with the Novelx miniature electron beam column and biased with a floating voltage to accelerate low-energy electrons demonstrate the effectiveness of SPDs for secondary electron detection. Based on these simulations and results, it is believed that SPDs present a reliable, inexpensive solution for secondary electron detection in miniature electron beam columns, as well as a robust mechanism for system calibration in column arrays for lithography.

Efficacy of continuous wear PureVision contact lenses for therapeutic use

Purpose: To evaluate the Bausch and Lomb PureVision™ contact lens as continuous wear contact lens for therapeutic and medical indications in a prospective open-ended non-randomized trial. Methods: Patients who required therapeutic contact lens wear for various indications such as pain relief, corneal protection, persistent epithelial defects, corneal perforation and chemical burns were fitted with PureVision™ continuous wear contact lenses (balafilcon A, 36% water content). Success or failure of specific treatment indication was assessed in each case with evaluation of ocular and lens related complications. Results: 30 eyes of 28 patients were fitted with PureVision™ continuous wear contact lenses. A successful fit was seen in 27 of 30 eyes with therapeutic success in 26 of 30 eyes. However, all patients reported symptomatic relief. Duration of lens use ranged from 3 days to 3 months. Dry eye was the most frequent cause of contact lens associated therapeutic failure. Complications included lens loss (two eyes), tight lens (one eye) and infective keratitis (two eyes). Conclusions: PureVision™ contact lenses were found to be safe and efficacious for continuous wear therapeutic use to a maximum of 90 days. The contact lens was also easier to handle by virtue of its resilient nature. There were no significant corneal complications of hypoxia, i.e. corneal oedema. Lens losses and deposits were minimal. The lens performance and fitting characteristics compares favorably with previous therapeutic lenses used by the investigators. This new lens may be considered as a safe and effective alternative for use as bandage contact lens.

Evaluation of soft contact lens fitting characteristics.

The assessment of soft contact lens fit by observation of the lens behavior on the eye is one of the most common procedures undertaken in contact lens practice. Nevertheless, the guidelines for doing so have been derived empirically with little or no research into the usefulness of these observations. Over 2000 evaluations of soft contact lens fit were analyzed to determine the predictive value of various indicators of contact lens fit, namely: subjective comfort, lens centration, postblink movement (PBM), version and upgaze lag, and tightness assessed by the push-up test. The receiver-operator characteristic (ROC) curves were prepared for each variable by plotting sensitivity values against false positive rates (FPRs) for various cut-off points. Sensitivity was defined as the proportion of "bad" fits correctly identified by a given variable; FPR was defined as the proportion of "good" fits incorrectly identified as bad fits. With each fitting variable, the optimum cut-off point and its corresponding sensitivity and FPR were determined from the ROC curves. Subjective comfort was found to be of little value in identifying tight fitting lenses but was of some limited value in identifying loose fitting lenses, particularly high water content (HWC) lenses. The push-up test was the most accurate single test of lens fit acceptability having a high sensitivity for both tight (92%) and loose (80%) lens fits. Assessment of PBM was a sensitive indicator of tight fitting lenses (95%), but was a poor indicator of loose fitting lenses, having a low sensitivity (51%). Assessment of version lag showed better sensitivity than upgaze lag in assessing loose fits, whereas upgaze lag showed better sensitivity for tight lens fits. Lens centration was of no predictive value in identifying tight fitting lenses but, as expected, was of some value in identifying loose fitting lenses. The results of this study enable a critical reassessment of the procedures that practitioners follow when fitting soft contact lenses.

Diurnal variation in human tear evaporation

Diurnal variations in tear evaporation in nine subjects were measured using resistance hygrometry at 2h intervals, fora 14h period. Evaporation is lowest on waking, and rises within 2h to a constant value for the rest of the day. Explanations for this pattern include low tear production during sleep and/or the presence of a thick tear film lipid layer on waking. These findings relate to observations of dry eye, lens adherence, corneal erosion, and tight lens syndrome in contact lens wear.

Production From Horizontal Wells After 5 Years

The first of four horizontal wells drilled by Elf Aquitaine during the last years produced its first barrel of oil in Aug. 1980. The others followed between 1981 and 1983. There is now enough production history to draw conclusions, some of which are surprising.

The design of the back surface ofgas permeable lenses

The introduction of gas permeable contact lenses into general practice has opened up a new era for practitioners, and the advantages over hard PMMA and soft lenses are well documented. For many new patients it will be quite possible to fit the standard hard lens designs which are favoured by the individual practitioner. However, for those wearers who subsequently suffer from flare, lens instability or lid irritation it is necessary to consider lenses with larger back central optic diameters and/or overall size and less edge lift. Similarly the soft lens wearer who is having to be refitted with a hard type lens will prefer immediate flare free stable vision which is not always immediately available with the standard hard lens constructions. In order to fulfil these requirements there have been several new designs offered for gas permeable lenses. To date these have received a mixed reception from practitioners and it is the purpose of this paper to compare these designs with the familiar PMMA constructions and offer new constructions which practitioners may find useful as an adjunct to those already available. Historically the initial interest with gas permeables goes back to CAB, but the lack of stability of lathe cutting reduced the effectivity of the material and forced us to consider moulded lenses such as the Hartflex from Wohlk. The edge lift of these lenses is, however, as little as 0.045mm, to 0.06ram,' and when fitted in the standard British fashion would lead to a very tight lens although giving often an amazing amount of tear interchange. Satisfaction is only really obtained utilizing a flatter than 'K' approach or by adding a flat edge curve about 0.5mm wide and blended into the lens periphery. The second lens introduced, the Menicon 02 works in a similar fashion. The lens like the Hartflex has a very reduced edge lift, varying from 0.06mm on steeper radii. These figures the manufacturers will not vary. Fitting this lens with apical clearance gives absolutely no edge lift, but fitted 0.15mm flatter than 'K' as suggested by the manufacturers means again we depart from conventional methods of fitting. At the same time as these lenses were introduced to Great Britain a similar investigation was being undertaken by Williams in the USA 2. He designed for the Syntex Corporation two series of lenses made from Polycon. The first set of lenses (Table 1) had an overall size of 9.50mm with a BCOD of 8.40ram, and an axial edge lift of about 0.12mm. No mention was

Newer Hard Contact Lens Materials

Despite the tidal wave of hydrophilic lenses onto the market over the past nine years, hard lenses refuse to die or fade away. In fact, in Australia, it appears that hard lenses now account for about 30 per cent of lenses made. Over the past three years some new non-hydrophilic (i.e.<5 per cent water) materials have become available in reasonable quantities, each claiming improved physiological performance on the eye. On paper and in vitro these claims appear to be substantiated but the acid test is in vivo. This paper is the outline of such an investigation. Three non-hydrophilic materials, PMMA, modified PMMA (BP Flex), and a CAB material were used, and the corneal response in terms of central corneal thickness and oxygen uptake on removal noted. Each subject was fitted with an optimum fitting lens, a slightly tight lens, and a very tight lens.

Corneal swelling caused by contact lens wear.

Corneal swelling caused by contact lens wear was investigated by measuring corneal thickness changes of several subjects wearing well- and poorly-fitted lenses. All subjects showed initial thickening. However, with continued wear, some corneas returned to normal thickness while others did not. At least two factors are believed to be responsible for the observed changes in corneal thickness. Increased lacrimation occurring during the adaptation period of contact lens wear may reduce tear film osmolarity, thereby causing 2% to 4% increase in thickness. A tightly-fitted contact lens appears to deprive the cornea of oxygen. Below some critical oxygen tension level under the lens, corneal swelling occurs. With a very tight lens, the swelling curve closely approximated that of a cornea in an oxygen-free environment.

On Legendrian surgeries between lens spaces

We obtain some obstructions to existence of Legendrian surgeries between tight lens spaces. We also study Legendrian surgeries between overtwisted contact manifolds.