Parametric Mid-Spatial Frequency Surface Error Synthesis

Standard mid-spatial frequency tooling mark errors were parameterized into a series of characteristic features and systematically investigated. Diffraction encircled and ensquared energy radii at the 90% levels from an unpowered optical surface were determined as a function of the root-mean-square surface irregularity, characteristic tooling mark parameters, fold mirror rotation angle, and incident beam f-number. Tooling mark frequencies on the order of 20 cycles per aperture or less were considered. This subset encompasses small footprints on single-point diamond turned optics or large footprints on sub-aperture tool polished optics. Of the characteristic features, off-axis fabrication distance held the highest impact to encircled and ensquared energy radii. The transverse oscillation of a tooling path was found to be the second highest contributor. Both impacts increased with radial tooling mark frequency.

The comorbidity of keratoconus and Fuchs' endothelial corneal dystrophy (clinical cases)

Purpose. To describe the clinical cases and surgery results in patients with concomitant of keratoconus and Fuchs' corneal endothelial dystrophy. Material and methods. Retrospective analysis of 3 patients using different surgical techniques. All patients were female, they underwent diagnostic procedures including: keratotopography, optical coherence tomography of the anterior segment of the eye, Scheimpflug keratotomography, endothelial microscopy. First patient underwent penetrating keratoplasty (PKP), the second one – descemet stripping automated endothelial keratoplasty (DSEK), and the third one – descemet membrane endothelial keratoplasty (DMEK). Results. In all cases the combination of keratoconus and fuchs endothelial corneal dystrophy occurred in one eye, while cornea guttata was observed in both eyes. The diagnosis of keratoconus was complicated by the presence of corneal edema due to endothelial dysfunction. As a result, visual rehabilitation was achieved in 2 patients after PKP and DSEK, and in the third case (DMEK), the presence of pronounced opacities of the stroma in the central zone did not result in increase of visual acuity, despite the good function of the graft endothelium, which required the PKP. Conclusion. Surgical tactics should be based primary on the replacement of the pathologically altered endothelial monolayer (DSEK, DMEK). As for the simultaneous replacement of the corneal stroma (PKP), the decision is based on the progression of keratoconus, the degree of corneal thinning, and the presence of its surface irregularity. Key words: Fuchs' endothelial corneal dystrophy, keratoconus, endothelial keratoplasty, penetrating keratoplasty, Descemet's membrane endothelial keratoplasty, corneal endothelium

Visual Acuity Approach to a Patient with a Rose-K Contact Lens - A Case Report

Objective- Providing a healthy satisfactory visual acuity approach to a patient of Keratoconus fitted with a Rose-K contact lens. Introduction- Rose K lens is an effective option for visual improvement in irregular cornea such as Keratoconus. Contact lenses are the mainstay therapy for Keratoconus and are the treatment modality of choice in 90% of patients due to corneal surface irregularity. Case History- A 32-year-old female patient visited at Ahooja Eye & Dental Institute, Gurugram, with the chief complaint of diminished vision in her left eye for the last one month. The patient did not complain about diminished vision in the right eye. Earlier, the patient had diagnosed with the case of Keratoconus somewhere else and suggested to be continued with the glasses. The patient had a history of spectacles in the last 7 years and using the current prescription for the last 4 months. Visual acuity for distance & near, with glass and the current prescription was recorded. Conclusion- In our case, after all the presented findings and trial, one pair of Rose K2 lenses of varying total diameter and optic zone diameter was ordered. The patient was asked to visit for lens collection and follow up after 6 months. Lastly, it is advised that all Rose k practitioners keep at least two to three trial lenses, assess the fit in each fit, and choose lenses based on corneal topography. Key words: Rose K Contact Lenses, Keratoconus, Visual Acuity, Topography.

Analysis of Dynamic Response of a Railway Locomotive Using ANSYS

Transient dynamic analysis (sometimes called time-history analysis) is a technique used to determine the dynamic response of a structure under the action of any general time-dependent loads. The time scale of the loading is such that the inertia or damping effects are considered to be important. Present work is focused on performing the time history analysis of a typical locomotive coach using finite element analysis in Indian railroad conditions. Track surface irregularity in the form of an ellipsoidal bump is modelled with assumptions that the vehicle passes over the bump in 0.144 seconds, variation in displacement at different key locations of the truck and car body models is plotted against time under standard loading conditions. The response pattern of the front and rear portions of the locomotive truck and car body indicate that these locations are more susceptible to wheel excitations compared to that of the centre portions of it as they are away from the centre of gravity of the vehicle due to unbalanced mass distribution.

High-throughput, label-free and slide-free histological imaging by computational microscopy and unsupervised learning

Rapid and high-resolution histological imaging with minimal tissue preparation has long been a challenging and yet captivating medical pursue. Here, we propose a promising and transformative histological imaging method, termed computational high-throughput autofluorescence microscopy by pattern illumination (CHAMP). With the assistance of computational microscopy, CHAMP enables high-throughput and label-free imaging of thick and unprocessed tissues with large surface irregularity at an acquisition speed of 10 mm2/10 seconds with 1.1-um lateral resolution. Moreover, the CHAMP image can be transformed into a virtually stained histological image (Deep-CHAMP) through unsupervised learning within 15 seconds, where significant cellular features are quantitatively extracted with high accuracy. The versatility of CHAMP is experimentally demonstrated using mouse brain/kidney tissues prepared with various clinical protocols, which enables a rapid and accurate intraoperative/postoperative pathological examination without tissue processing or staining, demonstrating its great potential as an assistive imaging platform for surgeons and pathologists to provide optimal adjuvant treatment.

Photocatalytic Activity of Fibrous Ti/Ce Oxides Obtained by Hydrothermal Impregnation of Short Flax Fibers

Fibrous Ti/Ce oxide photocatalysts were prepared for the first time by a biomimetic solution process using short flax fibers (flax straw processing waste) as a biotemplate. Titanium polyhydroxy complex solutions with 3% and 5% cerium were used as precursors. Flax fibers were impregnated in an autoclave under hydrothermal conditions. Ti/Ce oxides were obtained from the biotemplate by annealing at 600 °C. The photocatalytic activity of the Ti/Ce oxides was studied by the adsorption and decomposition of the dye rhodamine B under UV irradiation. The photocatalytic decomposition of the dye was 50% and 75% faster for Ti/Ce oxides with 3% and 5% Ce, respectively, than for the analogous undoped fibrous TiO2. The morphologies, textures, and structures of the photocatalysts were studied by scanning electron microscopy, low temperature N2 adsorption/desorption, UV-Vis spectroscopy, and X-ray and XPS analytical methods. It was shown that the introduction of Ce into the precursor solution increased the surface irregularity of the Ti/Ce oxide crystallites compared to pure TiO2. This effect scaled with the Ce concentration. Ce improved the UV light absorption of the material. The Ti/Ce oxides contained Ce4+/Ce3+ pairs that played an important role in redox processes and intensified the photocatalytic activity.

SIMULATION OF REFLECTION OF A PLANE ELECTROMAGNETIC WAVE IN A MULTILAYER MEDIUM: OIL-SATURATED FORMATION ENCLOSING A HYDRAULIC FRACTURE

Propagation of a plane electromagnetic wave of the microwave range is simulated to calculate the coefficient of its reflection from a homogeneous layer. A particular case of a multilayer geomediumis considered: an oil-saturated formation enclosing a hydraulic fracture. When justifying the choice of the frequency range, the value of fracture surface irregularity was taken into account. The dependence of the reflection coefficient on frequency for an electrically less dense non-absorbing layer inside a denser non-absorbing substance (a void layer inside a rock) has been calculated.

Abstract 35: Vessel Wall Magnetic Resonance Imaging Biomarkers of Symptomatic Intracranial Atherosclerosis: A Meta-Analysis

Background: Intracranial vessel wall MR imaging (VWI) may be able to identify imaging biomarkers of symptomatic plaque. A meta-analysis was performed to evaluate the strength of association of imaging features of symptomatic plaque on VWI and downstream ischemia. Methods: PubMed, Scopus, Web of Science, EMBASE and Cochrane databases were searched up to October 2019. Studies evaluating acute/subacute cerebrovascular ischemia using VWI on 1.5 or 3 Tesla MR were included. Studies with insufficient exclusion of other stroke etiologies, insufficient or duplicated data and conference abstracts were excluded. Two independent reviewers extracted data on study design, VWI techniques, imaging endpoints, and conducted a study design risk bias assessment using the QUADAS-2 tool. Per-lesion odds ratios (OR) were calculated and pooled using a bivariate random-effects model. Subgroup analyses and evaluation of publication bias were performed. Results: Twenty-one articles met inclusion criteria (1,750 lesions; 1,542 subjects). Plaque enhancement (OR 7.4, 95% CI 3.4-16.4; Figure), positive remodeling (OR 5.6, 95% CI 2.2-14.0), surface irregularity (OR 4.5, 95% CI 1.4-8.6), and T1 hyperintensity (OR 2.1, 95% CI 1.3-3.3) were significantly associated with downstream ischemia. T2 signal intensity was not significant (p=0.59). Plaque enhancement showed stronger associations when measured in retrospectively designed studies (OR 35.3, 95% CI 7.4-141, p=0.02), by a radiologist as a rater (OR 12.6, 95% CI 5.3-29.7, p<0.001), and on VWI pulse sequences with lower spatial resolution (OR 30.4, 95% CI 7.0-132.4, p=0.02). There was no publication bias (Egger’s test p=0.48). Conclusions: Plaque enhancement, positive remodeling, T1 hyperintensity and surface irregularity emerged as imaging biomarkers of symptomatic plaque. Plaque enhancement had the strongest association and remained significant accounting for sources of bias and variability in both study design and instrument.