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Author(s):  
Yusuf Osmani ◽  
Krishna Kela ◽  
Mona Sune

The human cornea is an avascular, transparent tissue that permits or allows light rays to enter or reach the retina. The cornea is made up of several layers, each of which plays an important role in preserving the transparency and power of cornea. The epithelium, Bowmans layer, Descemet’s membrane and endothelium are the layers of the cornea. This study aimed to discover the incidences of severe and non-severe corneal inflammation amongst wearers of modern technology touch lenses. Studies on touch lens users providing with a corneal ulcer/infiltrates were reported. On the basis of severity, a medical severity matrix was utilized among cases of severe and non-severe corneal inflammation. There was a large distinction in severe corneal infection among ew-hydrogel and ew-silicone hydrogel. When it comes to evaluating touch lens-related corneal inflammation, a medical severity matrix is available in hand. Wearers of contact lenses who sleep with them have a appreciably low risk of severe corneal inflammation than those who simplest  put on lenses for the duration of the day. Those cases who everyday sleep with lenses have a 5-fold lower risk of severe corneal inflammation as compared day-to-day hydrogel lenses for prolonged utilization.


Author(s):  
Nidhi Sohrot ◽  
Indrayani Jhadhav ◽  
Sohan Lohiya

Background: Astigmatism is an abnormality within the curvature of the attention. It occurs when light rays strike a spherical lens obliquely, or the line of vision to its principal axis is not parallel. Refraction away from the axis occurs when light strikes a lens obliquely and distorts the image formed. Aim: This study aimed to look at the prevalence of against-the-rule, with the-rule, and oblique-axis astigmatism in children. The change in cylinder index of refraction power and alignment of astigmatism in babies and young children is studied. Methodology: To conduct the study and thoroughly search the literature separately, references and abstracts were reviewed. Books like Parson’s diseases of the Eye by Dr. Radhika Tandon and several articles, WHO website, etc., were referred. Results: The study relied upon many studies on refractions procured by the near-retinoscopy methodology that knowledgeable Refractionist accomplished. Conclusion: It can be concluded that young children have a high incidence of against (???) type of astigmatism and that after this age (which age?), most children are with the rule.


2021 ◽  
Vol 65 (12) ◽  
pp. 1185-1193
Author(s):  
M. A. Bugaev ◽  
I. D. Novikov ◽  
S. V. Repin ◽  
A. A. Shelkovnikova

Abstract The problem of bending and scattering of light rays passing outside the entrance of a wormhole with zero gravitational mass is considered. The process of ray capture by a wormhole, as well as the formation process of a shadow when illuminated by a standard screen, is investigated. These mechanisms are also compared to the case of light ray motion in the vicinity of the Schwarzschild black hole.


2021 ◽  
Vol 34 (4) ◽  
pp. 464-469
Author(s):  
C. Y. Lo

Simulation shows that general relativity would lead to the existence of black holes if gravitation is always attractive. However, although we observed an invisible and extremely heavy object governs the orbits of stars at the center of our galaxy, we still cannot determine the existence of a black hole. Thus, one may ask whether black holes actually exist. Einstein’s general relativity has been established, because its prediction on the bending of light rays has been confirmed by observation. However, Einstein’s prediction on the increment of weight for a piece of metal as the temperature increases is proven incorrect by experiments, which actually show a reduction of weight. This leads to the necessary existence of repulsive gravitational force, which has been demonstrated by a charged capacitor hovering above the earth. Thus, Einstein, Newton, Galileo, and Maxwell all made the error of overlooking the repulsive gravitational charge-mass interaction. Thus, it is necessary to rejustify the existence of black holes, because gravity is not always attractive. Moreover, repulsive gravitational force makes it necessary to extend general relativity to a five-dimensional theory. Thus, to find out whether black holes exist, it is necessary to investigate the repulsive gravitation and a five-dimensional space.


Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2939
Author(s):  
Pengcheng Li ◽  
Donghe Pei

The investigation of objects in Minkowski space is of great significance, especially for those objects with mathematical and physical backgrounds. In this paper, we study nullcone fronts, which are formed by the light rays emitted from points on a spacelike curve. However, if the spacelike curve is singular, then we cannot use the usual tools and methods to study related issues. To solve these problems, we show the definition of spacelike framed curves in Minkowski 3-space, whose original curves may contain singularities. Then, the singularities of the nullcone fronts are characterized by using framed curvatures of spacelike framed curves. Finally, we exhibit some examples to illustrate our results.


2021 ◽  
Author(s):  
José Israel Galindo-Rodríguez ◽  
Gilberto Silva-Ortigoza

Abstract The aim of the present work is to introduce a lens whose faces are a conical surface and a spherical surface. We illuminate this lens by a plane wavefront and its associated refracted wavefronts, light rays and caustic are computed. We find that the caustic region has two branches and can be virtual, real or one part virtual and the other real, depending on the values of the parameters characterizing the lens. Furthermore, we present a particular example where one of the branches of the caustic region is constituted by two segments of a line, one part is real and the other one virtual. The second branch is a two-dimensional surface with a singularity of the cusp ridge type such that its Gaussian curvature is different from zero. It is important to remark that for this example, the two branches of the caustic are disconnected. Because of this property and the result obtained by Berry and Balazs on the relationship between the acceleration of an Airy beam and the curvature of its corresponding caustic, we believe that using this optical element one could generate a scalar optical accelerating beam in the region where the caustic is a two-dimensional surface of revolution, and at the same time a scalar optical beam with similar properties to the Bessel beam of zero order in the region were the real caustic is a segment of a line along the optical axis.


2021 ◽  
Vol 1 (2) ◽  
pp. 32-40
Author(s):  
A.M. Prasanna Kumar ◽  
Bharathi Gururaj

Moving picture entertainment is a foremost source of amusement for populace in today’s existence. To entertain populace a lot of investment is put into film production by the film makers. Their endeavour is being ruined by few people by pirate the movies substance. They do it by capture the video recording in mobile phone camera and upload it to websites or put up for sale it to people which cause huge loss. In this research work we are proposea novel technique for reduction of film piracy by avoiding fake video recordings of video in theatres. An indistinguishable luminosity is projected from the display to the whole spectators that falls on the camera lens which is sensitive to infrared light rays Makes the recorded video unfit to watch. A method is developed for anti-piracy system for film industry using steganography technique in MATLAB.


2021 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Mehrdad Sadeghi ◽  
Jalil Omidian

Context: Aberrometric analysis of the wavefront in patients with refractive disorders is performed using the Zernike pyramid mode and based on that, a treatment plan is determined however, it is not clear what Zernike modes are derived from mathematical analysis, exactly how much they correspond to the clinical facts this article discusses ways to study this issue. Evidence Acquisition: One of the methods for studying optical systems is the aberrometry of wavefront. the wavefront is a two-dimensional surface perpendicular to a bunch of parallel light rays, that all these rays have the same phase on this surface (because light emits sinusoidally and therefore has multiple identical phases) whenever these rays pass through a refractive surface, it is also called the reference level this refractive index will be ideal if the homogeneity of these rays is maintained and the rays of this bunch of light will be able to focus at one point, but if the by passing light through the refractive surface the wavefront will be disturbed and the lights on this surface have different phases than the reference surface then it is said there is a discrepancy or deviation between the reference surface and the wavefront. Therefore, aberration is the creation of the distance of the wavefront in a certain phase from the refractive surface or reference surface. When we say refractive surface, we do not mean a specific place like the cornea because other than the cornea other factors such as crystalline lens, vitreous, retin even tear layer they are involved in creating aberrations, but usually the pupil range is considered as the reference surface. Results: Modes z-13 and z13 of the fourth order and modes z04 and z-24, z24 from the fifth order and modes z-15, z15 of six order and modes z06, z-26, z26 of seventh order they are not pure and mathematically they have some lower order which may cause in analysis aberrometry disruption as a result, the relevant orders have a little more or less value. Conclusions: There are no strong clinical reasons for Zernike modes to be a fully accurate description of aberromerty, so clinicians should consider other clinical data and findings in their interpretation. Some modes of high-order Zernike have sentences of low-order This can cause abnormal analysis.


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