Realistic Lens Research Articles

Wave optical propagation in realistic lens systems through multi-slice decomposition with phase compensation

A fast and accurate optical simulation is essential in the design and analysis of optical systems. We propose a wave propagation method through multi-slice decomposition with phase compensation (MSDP) to calculate the wave propagation in realistic lens systems. An estimation of the phase compensation term for the refraction effect and diffraction effect is given, and a modified phase compensation term is presented for calculation through optical systems with a high numerical aperture or an incident optical field featuring a broad spectrum. The proposed method yields accurate and fast results for micro-optical lens systems with the radius of curvature comparable to an illumination wavelength. In a macroscopic optical system with a high numerical aperture, an object with abundant spatial frequencies is reconstructed from the diffraction patterns produced by a single aspherical lens, further demonstrating the effectiveness and applicability of the method in realistic lens systems.

A new step forward in realistic cluster lens mass modelling: analysis of Hubble Frontier Field Cluster Abell S1063 from joint lensing, X-ray, and galaxy kinematics data

ABSTRACT We present a new method to simultaneously and self-consistently model the mass distribution of galaxy clusters that combines constraints from strong lensing features, X-ray emission, and galaxy kinematics measurements. We are able to successfully decompose clusters into their collisionless and collisional mass components thanks to the X-ray surface brightness, as well as use the dynamics of cluster members, to obtain more accurate masses exploiting the fundamental plane of elliptical galaxies. Knowledge from all observables is included through a consistent Bayesian approach in the likelihood or in physically motivated priors. We apply this method to the galaxy cluster Abell S1063 and produce a mass model that we publicly release with this paper. The resulting mass distribution presents different ellipticities for the intra-cluster gas and the other large-scale mass components as well as deviation from elliptical symmetry in the main halo. We assess the ability of our method to recover the masses of the different elements of the cluster using a mock cluster based on a simplified version of our Abell S1063 model. Thanks to the wealth of mutliwavelength information provided by the mass model and the detected X-ray emission, we also found evidence for an ongoing merger event with gas sloshing from a smaller infalling structure into the main cluster. In agreement with previous findings, the total mass, gas profile, and gas mass fraction are all consistent with small deviations from the hydrostatic equilibrium. This new mass model for Abell S1063 is publicly available, as the lenstool extension used to construct it.

Streamlined lensed quasar identification in multiband images via ensemble networks

Quasars experiencing strong lensing offer unique viewpoints on subjects related to the cosmic expansion rate, the dark matter profile within the foreground deflectors, and the quasar host galaxies. Unfortunately, identifying them in astronomical images is challenging since they are overwhelmed by the abundance of non-lenses. To address this, we have developed a novel approach by ensembling cutting-edge convolutional networks (CNNs) - for instance, ResNet, Inception, NASNet, MobileNet, EfficientNet, and RegNet – along with vision transformers (ViTs) trained on realistic galaxy-quasar lens simulations based on the Hyper Suprime-Cam (HSC) multiband images. While the individual model exhibits remarkable performance when evaluated against the test dataset, achieving an area under the receiver operating characteristic curve of >97.3% and a median false positive rate of 3.6%, it struggles to generalize in real data, indicated by numerous spurious sources picked by each classifier. A significant improvement is achieved by averaging these CNNs and ViTs, resulting in the impurities being downsized by factors up to 50. Subsequently, combining the HSC images with the UKIRT, VISTA, and unWISE data, we retrieve approximately 60 million sources as parent samples and reduce this to 892 609 after employing a photometry preselection to discover z > 1.5 lensed quasars with Einstein radii of θE < 5″. Afterward, the ensemble classifier indicates 3080 sources with a high probability of being lenses, for which we visually inspect, yielding 210 prevailing candidates awaiting spectroscopic confirmation. These outcomes suggest that automated deep learning pipelines hold great potential in effectively detecting strong lenses in vast datasets with minimal manual visual inspection involved.

The redshift difference in gravitational lensed systems: a novel probe of cosmology

ABSTRACT The exploration of the redshift drift, a direct measurement of cosmological expansion, is expected to take several decades of observation with stable, sensitive instruments. We introduced a new method to probe cosmology that bypasses the long-period observation by observing the redshift difference, an accumulation of the redshift drift, in multiple-image gravitational lens systems. With this, the photons observed in each image will have traversed through different paths between the source and the observer, and so the lensed images will show different redshifts when observed at the same instance. Here, we consider the impact of the underlying cosmology on the observed redshift difference in gravitational lens systems, generating synthetic data for realistic lens models and exploring the accuracy of determined cosmological parameters. We show that, while the redshift difference is sensitive to the densities of matter and dark energy within a universe, it is independent of the Hubble constant. Finally, we determine the observational considerations for using the redshift difference as a cosmological probe, finding that one thousand lensed sources are enough to make robust determinations of the underlying cosmological parameters. Upcoming cluster lens surveys, such as the Euclid, are expected to detect a sufficient number of such systems.

Optical modeling of the entire visual field of the eye.

Vision is rarely evaluated scientifically at very large visual angles, despite being used continuously in everyday life. Furthermore, raytrace calculations indicate that peripheral optical properties are different for a pseudophakic eye, and even though this is rarely noted by patients, it is probably the cause of bothersome "negative dysphotopsia." Simplified paraxial parameters that characterize the basic properties of phakic and pseudophakic eyes are collected together here as a baseline, and then raytracing is used to show that input angles of about 60°, which correspond to obstruction by the nose, eyebrow, and cheek, illuminate a retinal hemisphere. At larger angles in the temporal direction, the image with an intraocular lens (IOL) reaches a limit due to vignetting at about a 90° input angle to the optical axis, in comparison to 105° with the Gullstrand-Emsley eye model, and 109° for the most realistic gradient index crystalline lens model. Scaling the far peripheral vision region more accurately may lead to benefits relating to intraocular lenses, diseases of the peripheral retina, widefield fundus images, and myopia prevention.

Traces of Marxism leading to Color Prejudice in the Novel based drama

The character of Parizaad from the drama Parizaad, aired on Hum TV in 2021, is the subject of the current study. Using Marxist theory, we were able to better understand the character of Parizaad in the narrative. The qualitative analysis of the data was carried out by the researcher. Its possible that Marxism had an influence onthis drama. Hashims Urdu novel Parizaad shows the terrible reality of Pakistani society in all its complexity, and is a must-read for anybody interested in the countrys history. For a change, its a breath of fresh air to read a story that takes on Pakistani societys laws as well as the rich and powerful in such a straightforward way. Numerous Parizaad have died as a result of the current societal system crushing them under its weight. Race, injustice, and socioeconomic inequality are just a few of the issues that are addressed in it. It has been identified that the drama portrayed the racial and class discrimination in the society through realistic lens and exposed the plight of the poor, marginalized and often ridiculed poor class.

Embracing Resiliency: Practical Strategies to Minimize Teacher Burnout and Elevate Retention

Teacher shortage constitutes a crisis in the U.S. and the education system at-large. In light of the crisis of teacher shortage and the severity of turnover rate, the purpose of this paper is to join in the dialogue to further the conversation regarding how believing or reinforcing stereotypes can contribute to burnout and unrealistic expectations teachers face in education. Suggestions for pre-service and in-service teachers to acquire a more realistic and resilient lens for themselves as educators and the profession is presented. The following themes will be explored: collaboration, embracing vulnerability, empowerment and agency, support and mentoring, and self-care and resiliency.

Getting policy done in educational practice: What happens when multiple central government policies meet clusters of organization routines in schools

This paper develops a new, broader, and more realistic lens to study (lacking) linkages between government policy and school practices. Drawing on recent work in organization theory, we advance notions on cluster of organization routines and the logic of complementarities underlying organizational change. This lens allows looking at how schools do (not) change a cluster of organization routines in response to multiple, simultaneous demands posed by government policies. Thirteen purposively selected Dutch secondary schools responding to three central government policies calling for concurrent change were analyzed, taking the schedule of a school as an exemplary case of a cluster of organization routines. Five distinct responses were distinguished, which can be sorted according to their impact on the whole organization. The study finds that ten of the thirteen schools did not change anything in response to at least one of the three policies we studied. However, all schools changed their cluster of organization routines, which impacted the whole organization in response to at least one of the three government policies. Therefore, looking at combinations of responses and considering the impact of change on school organizations qualifies ideas about schools being resistant to policy or unwilling to change and improve.

ВЛИЯНИЕ ЗАРЯДА В ЧЕРНОЙ ДЫРЕ БАРДИНА НА ЗАДЕРЖКУ ВРЕМЕНИ ПРИБЫТИЯ СИГНАЛОВ

In this paper we consider an impact of Bardeen black hole charge on times of arrival of signals on the time delay caused by frame-dragging effect. This effect can arise in astrophysical systems, where one of the companions of the binary system emits a variable electromagnetic signal. A variable signal travels on both sides of a rotating object in the equatorial plane. We consider a spherically symmetric regular black hole by Bardeen as a rotating object, which has a deviation parameter g besides mass M and spin a. This parameter is related to the described nonlinear electrodynamics, and the Bardeen metric reduces to the Kerr metric when g = 0. We investigate times of arrival of signals effect in a realistic final lens system in a Bardeen black hole compared to a Kerr–Newman black hole. It is noteworthy that an influence of electric charge on the time delay in the Kerr–Newman black hole appears in the second and third orders, and an influence of the charge in the Bardeen black hole only in the third order. The contribution of the leading-order time delay with the capabilities of modern equipment is fundamentally measurable, however, the influence of the charge manifests itself only in the third, therefore, this study is more of academic interest than practical. For the binary system pulsar – black hole Cygnus X-1, numerical values were tabulated.

Multipole decomposition of gravitational lensing

We study gravitational lensing by a generic extended mass distribution. For that, we consider the diffraction of electromagnetic (EM) waves by an extended, weakly aspherical, gravitating object. We account for the static gravitational field of such a lens by representing its exterior potential in the most generic form, expressed via an infinite set of symmetric trace free (STF) tensor multipole mass moments. This yields the most general form of the gravitational phase shift, which allows for a comprehensive description of the optical properties of a generic gravitational lens. We found that at each order of the STF moments, the gravitational phase shift is characterized by only two parameters: a magnitude and a rotation angle that characterize the corresponding caustics, which form in the point spread function (PSF) of the lens. Both of these parameters are uniquely expressed in terms of the transverse-trace free (TT) projections of the multipole moments on the lens plane. Not only does this result simplify the development of physically consistent models of realistic lenses, it also drastically reduces the number of required parameters in the ultimate model. To help with the interpretation of the results, we established the correspondence of the gravitational phase shift expressed via the TT-projected STF multipole mass moments and its representation via spherical harmonics. For axisymmetric mass distributions, the new results are consistent with those that we obtained in previous studies. For arbitrary mass distributions, our results are novel and offer new insight into gravitational lensing by realistic astrophysical systems. These findings are discussed in the context of ongoing astrophysical gravitational lensing investigations as well as observations that are planned with the solar gravitational lens (SGL).

Gender-Based Violence and Deprivation of the Child Rights in the Context of Bangladesh and Sweden: A Study Based on Migration—A True Event of Deprivation of Swedish Asylum Act

Anthropology at home is regarded as a realistic lens to see the real picture of the Social Construction of various countries because of the ongoing shocks of gender-based violence. It is becoming increasingly difficult to judge this field of gender-based violence (GBV) in a variety of social, economic, cultural, and political situations. Poverty, inequality, and women’s empowerment are all major issues that face us today. With the help of events and thoughts, carrying all these associated areas of this domain around the world. Maintained the stance that “All of us are natives now” during the 1970s (Peirano, 1998), and in the 1980s, but with a caution from the more established society that the transition from home to abroad was not easy. Many people regarded doing their homework at home as a challenging assignment, and it was advised to trust the researcher who had expertise elsewhere (Peirano, 1998). In this regard, I feel compelled to share my research-related experiences to examine the various forms of GBV both domestically and internationally. In Sweden 2020, 16,461 assault cases were reported against women in close relationships. That is a 15.4% rise from the 2019 figure of 14,261, reported by the National Council for Crime Prevention. While In Bangladesh According to a recent study of 38,125 women by a human rights organization in 53 of Bangladesh’s 64 districts, 4622 women had experienced mental torture, 1839 had experienced physical abuse, and 203 had experienced sexual assault (Manusher Jonno Foundation, 2020). For Comparative analysis “A true event” has been used as a case study to examine the causes and effects of various forms of discrimination concerning violence against women. That environment may support a personal concern for the historical knowledge of the GBV in cultural anthropology. The article aims to demonstrate how engaging GBV in human trafficking by intimidation and how a Swedish permanent residence holder woman by asylum and her children are deprived based on Swedish alien act and policy through different precedence of structural work in Swedish migration board, the court of Sweden, Civil servant (migration officer), Interview officer. Following the universal act CRC (Convention on the rights of the children) in regards to “the best interest” of the child, the right to life, survival, and development, and respect for the views of the child is questioned comparing Swedish alien act in action. These approaches acknowledge that something special is produced by Different Types of Discrimination in Two Countries Bangladesh and Sweden to identify the true sources of different human rights violence.

The “hard, relentless, never-ending” work of focusing on discharge: a qualitative study of managers' perspectives

PurposeInterventions to hasten patient discharge continue to proliferate despite evidence that they may be achieving diminishing returns. To better understand what such interventions can be expected to accomplish, the authors aim to critically examine their underlying program theory.Design/methodology/approachWithin a broader study on patient flow, spanning 10 jurisdictions across Western Canada, the authors conducted in-depth interviews with 300 senior, middle and frontline managers; 174 discussed discharge initiatives. Using thematic analysis informed by a Realistic Evaluation lens, the authors identified the mechanisms by which discharge activities were believed to produce their impacts and the strategies and context factors necessary to trigger the intended mechanisms.FindingsManagers' accounts suggested a common program theory that applied to a wide variety of discharge initiatives. The chief mechanism was inculcation of a sharp focus on discharge; reinforcing mechanisms included development of shared understanding and a sense of accountability. Participants reported that these mechanisms were difficult to produce and sustain, requiring continual active management and repeated (re)introduction of interventions. This reflected a context in which providers, already overwhelmed with competing demands, were unlikely to be able (or perhaps even willing) to sustain a focus on this particular aspect of care.Originality/valueThe finding that “discharge focus” emerged as the core mechanism of discharge interventions helps to explain why such initiatives may be achieving limited benefit. There is a need for interventions that promote timely discharge without relying on this highly problematic mechanism.

Diffraction of electromagnetic waves by an extended gravitational lens

We continue our study of the optical properties of the solar gravitational lens (SGL). Taking the next step beyond representing it as an idealized monopole, we now characterize the gravitational field of the Sun using an infinite series of multipole moments. We consider the propagation of electromagnetic (EM) waves in this gravitational field within the first post-Newtonian approximation of the general theory of relativity. The problem is formulated within the Mie diffraction theory. We solve Maxwell's equations for the EM wave propagating in the background of a static gravitational field of an extended gravitating body, while accounting for multipole contributions. Using a wave-theoretical approach and the eikonal approximation, we find an exact closed form solution for the Debye potentials and determine the EM field at an image plane in the strong interference region of the lens. The resulting EM field is characterized by a new diffraction integral. We study this solution and show how the presence of multipoles affects the optical properties of the lens, resulting in distinct diffraction patterns. We identify the gravitational deflection angle with the individual contributions due to each of the multipoles. Treating the Sun as an extended, axisymmetric, rotating body, we show that each zonal harmonics causes light to diffract into an area whose boundary is a caustic of a particular shape. The appearance of the caustics modifies the point-spread function (PSF) of the lens, thus affecting its optical properties. The new wave-theoretical solution allows the study gravitational lensing by a realistic lens that possesses an arbitrary number of gravitational multipoles. This {\em angular eikonal method} represents an improved treatment of realistic gravitational lensing. It may be used for a wave-optical description of many astrophysical lenses.

Advancing Food Well-Being in Poverty Through Intersectionality

This article explores the importance of employing intersectionality when investigating food well-being (FWB) in poverty framework. We argue that this approach provides a more nuanced and realistic lens for both marketers and policy makers when developing FWB strategies in the context of poverty. To this end, this article focuses on the intersection of ethnicity and gender to examine food consumption practices of two groups of women living in poverty in Bangladesh. Specifically, the research design uses semi-structured interviews with 16 Santal (ethnic minority) and 14 Muslim (ethnic majority) women to explore commonalities and differences in their consumption experiences. The findings provide new insights into how marketers and policy makers can engage with diverse ethnic communities to enhance their FWB. This article contributes to the FWB literature by introducing intersectionality as a mechanism to uncover differences in advantage and disadvantage based on overlapping categories of ethnicity, gender, and class. Implications for marketers and policy makers include (a) developing food policies that pay attention and respect to cultural norms and sociohistorical experiences, (b) creating and shaping social networks, (c) investing in infrastructure and utilities that prioritize ethnic minorities, and (d) seeking out jugaad (frugal) innovations.

Eigenlenses: a new model for full crystalline lens shape representation and its applications.

The crystalline lens is an important optical element in the eye, responsible for focusing, and which experiences significant changes throughout life. The shape of the lens is usually studied only in the optical area (central 4 to 6 mm). However, for a great number of applications, a description of the full shape of the crystalline lens is required. We propose a new method for the representation of the full shape of the crystalline lens, constructed from 3-dimensional optical coherence tomography images of 133 isolated crystalline lenses (0-71 y/o), which we have called eigenlenses. The method is shown to be compact and accurate to describe not only the full shape of the crystalline lens, but also the optical zone in comparison with other methods. We also demonstrate its application to the extrapolation of the full shape of the crystalline lens from in-vivo optical images of the anterior segment of the eye, where only the central part of the lens visible through the pupil is available, and in the generation (synthesis) of realistic full lenses of a given age. The method has critical applications, among others, in improving and evaluating myopia and presbyopia treatments.

Physiology-like crystalline lens modelling for children

Understanding the age-dependent properties of the crystalline lenses of children is fundamental in studying the mechanism of myopic development and progression. A more realistic lens structure has more power for predicting the optical properties of the crystalline lenses. In this manuscript, a new lens model is proposed to predict the age-dependent change in the crystalline lens for children aged 6 to 15 years old. The lens model has the capability of involving most parameters measurable on the in vivo human lens. Moreover, the discrepancy of refractive indices at the equatorial edge and anterior and posterior vertices of the external lens surface is explained systematically. The analysis shows that this discrepancy has a significant role on the optical performance of the lens. The age-dependent properties are modelled based on available experimental data. The relationship between structural and optical performance is investigated with three-dimensional ray-tracing. The contributions of each parameter to the optical power and spherical aberration are revealed. The study has highlighted the importance of building physiology-like crystalline lens structure since some parameters ignored by previous studies can have a great optical impact.

Deep convolutional neural networks as strong gravitational lens detectors

Context. Future large-scale surveys with high-resolution imaging will provide us with approximately 105 new strong galaxy-scale lenses. These strong-lensing systems will be contained in large data amounts, however, which are beyond the capacity of human experts to visually classify in an unbiased way. Aims. We present a new strong gravitational lens finder based on convolutional neural networks (CNNs). The method was applied to the strong-lensing challenge organized by the Bologna Lens Factory. It achieved first and third place, respectively, on the space-based data set and the ground-based data set. The goal was to find a fully automated lens finder for ground-based and space-based surveys that minimizes human inspection. Methods. We compared the results of our CNN architecture and three new variations (“invariant” “views” and “residual”) on the simulated data of the challenge. Each method was trained separately five times on 17 000 simulated images, cross-validated using 3000 images, and then applied to a test set with 100 000 images. We used two different metrics for evaluation, the area under the receiver operating characteristic curve (AUC) score, and the recall with no false positive (Recall0FP). Results. For ground-based data, our best method achieved an AUC score of 0.977 and a Recall0FP of 0.50. For space-based data, our best method achieved an AUC score of 0.940 and a Recall0FP of 0.32. Adding dihedral invariance to the CNN architecture diminished the overall score on space-based data, but achieved a higher no-contamination recall. We found that using committees of five CNNs produced the best recall at zero contamination and consistently scored better AUC than a single CNN. Conclusions. We found that for every variation of our CNN lensfinder, we achieved AUC scores close to 1 within 6%. A deeper network did not outperform simpler CNN models either. This indicates that more complex networks are not needed to model the simulated lenses. To verify this, more realistic lens simulations with more lens-like structures (spiral galaxies or ring galaxies) are needed to compare the performance of deeper and shallower networks.

Simulations of simple Bovine and Homo sapiens outer cortex ocular lens membrane models with a majority concentration of cholesterol

The lipid composition of bovine and human ocular lens membranes has been probed, and a variety of lipids have been found including phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), and cholesterol (CHOL) with cholesterol being present in particularly high concentrations. In this study, we use the all-atom CHARMM36 force field to simulate binary, ternary, and quaternary mixtures as models of the ocular lens. High concentration of cholesterol, in combination with different and varying diversity of phospholipids (PL) and sphingolipids (SL), affect the structure of the ocular lens lipid bilayer. The following analyses were done for each simulation: surface area per lipid, component surface area per lipid, deuterium order parameters (SCD), electron density profiles (EDP), membrane thickness, hydrogen bonding, radial distribution functions, clustering, and sterol tilt angle distribution. The SCD show significant bilayer alignment and packing in cholesterol-rich bilayers. The EDP show the transition from liquid crystalline to liquid ordered with the addition of cholesterol. Hydrogen bonds in our systems show the tendency for intramolecular interactions between cholesterol and fully saturated lipid tails for less complex bilayers. But with an increased number of components in the bilayer, the acyl chain of the lipids becomes a less important characteristic, and the headgroup of the lipid becomes more significant. Overall, cholesterol is the driving force of membrane structure of the ocular lens membrane where interactions between cholesterol, PL, and SL determine structure and function of the biomembrane. The goal of this work is to develop a baseline for further study of more physiologically realistic ocular lens lipid membranes.This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo.

Radiometric imaging by double exposure and gain calibration.

Due to low cost and small size, uncooled microbolometer-based thermal focal plane arrays are very attractive for radiometry. However, being non-cooled, they suffer from temporally and spatially dependent changes that require constant calibration. While the gain calibration can be reasonably realized by two-point correction, the offset due to internal radiation loads poses a complicated calibration scheme. We present a new computational optics approach that simplifies the essential calibration for temperature offset. Using two successive images of the object taken with different known blur levels, one can eliminate the object term from the image-formation equation, resulting in an equation for the unknown sensor offset. A general algebraic model is presented for the space-variant case followed by solutions using both direct inverse method and iterative solver. The new scheme allows restoration of the radiometric value within 1% error with the direct method, and 0.2% error with the iterative scheme. Account of the influence of realistic lens positioning error on restoration accuracy was given. Results using direct inverse methods for restoring the radiometric values yield restoration error with a good average error of 3.7% and less.

Distinction between image magnification and irradiance magnification: a commentary

We take a closer look at the transverse magnification factor m in Eqs. (4) and (7) in a recent paper by Reshidko and Sasian and suggest that a distinction be made between the square of the “first-order transverse magnification” and the “magnification of the irradiance.” When applied to image irradiance calculations, the former quantity is restricted to aberration-free lenses, whereas the latter is not. For realistic lenses (i.e., lenses whose aberrations are not totally zero, but function sufficiently well), as might be expected, these two magnification quantities are generally not equal, except in the limit of low numerical aperture.