Black Shadow Research Articles

ClarityDiffuseNet: Enhancing fundus image quality under black shadows with diffusion model-based research

Deep learning models have achieved commendable success in the analysis of tasks related to fundus images. However, the performance of many models is affected by the quality of fundus images. A common quality issue observed in fundus images is the presence of severe black shadow artefact, primarily caused by opacities in the refractive media or due to insufficient or uneven illumination. Such low-quality images can compromise the model training and result in the models learning incorrect feature representations. The removal of black shadows can be regarded as a preprocessing problem in the enhancement of degraded images. Solutions typically involve either increasing the overall brightness of the image or restoring the dark shadowy areas. Prior work on increasing image brightness has often utilized generative adversarial networks (GANs), while restoration has been approached with autoencoders and variational autoencoders (VAEs). However, approaches that focus on brightening often fall short in properly addressing local degradations, and restoration techniques can lead to loss of details or over-smoothing in the shadow areas.In this study, we introduce a method named ClarityDiffuseNet, a model for restoring low-quality fundus images based on diffusion generative models targeting severe black shadows. Our method restores areas with black shadows from regions of high quality, enhancing the image to be richer in detail and visually closer to artefact-free images. Compared to models based on GANs and inpainting methods, our approach demonstrates superior performance on four benchmark public datasets, with Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity index (SSIM) indices significantly surpassing the state-of-the-art models by 7% and 9%, respectively. Our method demonstrates notable improvements in downstream tasks, such as disease diagnosis—evidenced by 9% increase in the area under the curve (AUC) metric when tested on low-quality datasets—in vessel segmentation, which saw about 6% improvement in the Dice coefficient under similar conditions. These outcomes underscore the substantial promise of diffusion generative models within the realm of fundus image restoration, highlighting their effectiveness in enhancing image quality for further analysis.

Black hole evaporation process and Tangherlini–Reissner–Nordström black holes shadow

In this article, we study the black hole evaporation process and shadow property of the Tangherlini-Reissner-Nordström (TRN) black holes. The TRN black holes are the higher-dimensional extension of the Reissner-Nordström (RN) black holes and are characterized by their mass M, charge q, and spacetime dimensions D. In higher-dimensional spacetime, the black hole evaporation occurs rapidly, causing the black hole’s horizon to shrink. We derive the rate of mass loss for the higher-dimensional charged black hole and investigate the effect of higher-dimensional spacetime on charged black hole shadow. We derive the complete geodesic equations of motion with the effect of spacetime dimensions D. We determine impact parameters by maximizing the black hole’s effective potential and estimate the critical radius of photon orbits. The photon orbits around the black hole shrink with the effect of the increasing number of spacetime dimensions. To visualize the shadows of the black hole, we derive the celestial coordinates in terms of the black hole parameters. We use the observed results of M87 and Sgr A∗ black hole from the Event Horizon Telescope and estimate the angular diameter of the charge black hole shadow in the higher-dimensional spacetime. We also estimate the energy emission rate of the black hole. Our finding shows that the angular diameter of the black hole shadow decreases with the increasing number of spacetime dimensions D.

Exploring the quintessential influence on shadows of black holes in Finsler-Hayward geometry

This research aims to shed light on how the quintessential dark energy influences the shadows cast by black holes by considering different kinds of surrounding accretion profiles within the framework of Finsler-Hayward geometry. We explore the impact of the Finsler parameter (η) and the quintessence parameter (ω) on fundamental properties of the black hole, such as its horizons, photon sphere, and impact parameter. By examining the observed characteristics of the black hole's shadow, including the photon ring and shadow intensities, we analyze how the quintessence affects these features under varying scenarios of matter accretion. Leveraging observational data from the Event Horizon Telescope, exclusively focusing on celestial bodies such as Sgr A* and M87*, we narrow down the range of the Finsler parameter (η) within our model of quintessence-infused Finsler Hayward black holes. By comparing our findings with models such as Finsler Schwarzschild, with and without the quintessence Finsler Hayward black holes, we observe that the quintessence's influence on the black hole's shadow surpasses the effects attributed to regularity. This study contributes to our insight into how the Finsler parameter and the quintessence of dark energy shape the shadows of black holes in diverse accretion environments, shedding light on their intricate nature and behavior, particularly in the context of Finsler Hayward geometry.

Barriers to maintaining dignity for patients with schizophrenia: A qualitative study.

Since dignity is one of the fundamental rights of each patient, maintaining patients' dignity is essential. Unfortunately, in many cases, particularly among patients with schizophrenia (SCZ), dignity is not fully respected. Nonetheless, there is limited knowledge regarding this matter in Middle Eastern Nations. This study aimed to identify the barriers to maintaining dignity for patients with schizophrenia from the perspective of patients with schizophrenia, their family caregivers, and healthcare personnel. This qualitative study was conducted with patients (n = 16), family caregivers (n = 4), and healthcare personnel (n = 6) who were selected using a purposeful sampling method. The data were collected through semi-structured, in-depth face-to-face interviews until the data reached saturation. Data were analyzed using the Graneheim and Lundman method. The Research Ethics Committee of Urmia University of Medical Sciences (IR.UMSU.REC.1401.099). Analysis of the interviews revealed two main themes and five subthemes as the barriers to maintaining dignity for patients with schizophrenia. The main themes included "Black shadow of stigma" (three subthemes: "Facing the fear and discrimination of others," "Misconceptions in society," and "Social rejection") and "Facing violations" (two subthemes: "Basic human rights violation" and "Negative emotional responses"). Patients' dignity with schizophrenia was at a low level due to the negative attitude of society toward these patients. In this respect, the basic human rights violations, social rejection, and misconceptions were abundant in society and care centers. An in-depth comprehension of the threatening factors affecting dignity can assist policymakers in safeguarding their dignity through effective programs.

Intrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage of both eyes after COVID-19 infection: a case report

BackgroundIntrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage is commonly observed in myopia with tilted optic disc. It presents with typical features on the fundus and follows a self-limiting course. However, due to its complex etiology, clinicians sometimes lack sufficient understanding of it which can easily lead to misdiagnosis or overtreatment. In this case report, we describe a rare case of intrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage in both eyes.Case presentationAn 18-year-old female who has no past medical history experienced sudden black shadow blocking of her right eye in the right eye for the past 2 days after a 5-day history of COVID-19 infection. The best corrected visual acuity is 0.5 in the right eye and 0.6 in the left eye. Optical coherence tomography (OCT) showed tilted optic discs in both eyes, bulged nasal optic discs, and the presence of strong reflective material under the parafoveal retina of the optic discs. Fundus fluorescein angiography (FFA) showed subretinal fluorescence occlusion above and nasolateral to the optic disc in the right eye, with hypofluorescence below the optic disc; the subretinal below the optic disc was obscured by vitreous hemorrhage; hypofluorescence was seen in the optic disc region of the left eye.COVID-19 antigen was positive. The patient was in the early stage of the third COVID-19 infection when the disease occurred. We speculate that it may be related to it. After 5 months of conservative treatment, the patient’s hemorrhage disappeared in both eyes and her best corrected visual acuity returned to normal.ConclusionsIntrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage usually occurs in myopia with tilted optic disc. In most patients, the cause of the bleeding is unknown, but it can gradually resolve under clinical observation or conservative treatment.

The Study on the Fundamental of Dark and Bright Solitons

Abstract: The words bright and dark are taken from the field of optics, where they are used to describe the bright spots and black shadows that appear in optical fibres. However, in the 1830s, soliton observations were made in water. Oceanographers were initially taken aback by the discovery in the 1960s and 1970s that bright solitons were present on the surface of deep ocean waters. However, numerous experiments have since been conducted to investigate and validate the phenomenon, some of which have identified bright solitons as the cause of rogue waves at sea. Both bright and dark solitons have now been observed in BoseEinstein condensates, plasmas, fibre optics, and other environments. [30]

Shadows of quintessential dark energy black holes in the domain of outer communication

The rotating black holes in the quintessential dark energy correspond to three horizons: inner, outer, and quintessential horizon. The domain of outer communication is the region between outer and quintessential horizon. Here in this work, we study the photon region and shadows of the quintessential dark energy black holes when the observer stays statically in the domain of outer communication. The quintessential dark energy black holes shadow characterizes by its mass (M), spin parameter (a), quintessential dark energy parameter (ωq), and normalization factor (γ). The dark energy parameter ωq can take values between −1.1<ωq<−1/3 and follows the equation of state ωq = pressure(p)/energy density(ρq). This state parameter significantly affects the shape and the size of the black hole shadow. We generalize all the geodesic equations of motion for ωq and obtain relation to visualizing the black hole shadow by a static observer at any arbitrary distance in the domain of outer communication. We estimate the black hole shadow observables: radius Rs, distortion parameter δs, and the shadow area A. Using the numerical values of shadow radius Rs and area A, we obtain the angular diameter (θd) of the black hole shadow. The angular diameter of the M87 and Sgr A∗ black holes shadow are 42±3μas and 48.7±7μas respectively as observe by Event Horizon Telescope (EHT). In this case, the angular diameter of the black hole shadow varies from θd≈21o±4 with γ from 0.08/M to 0.12/M for the state parameter ωq=−2/3 when the static observer at ro=5M in the domain of outer communication.

FRBNet: Feedback refinement boundary network for semantic segmentation in breast ultrasound images

Ultrasound breast tumour segmentation is a key step in computer-aided diagnosis and provides an important basis for clinical diagnosis and analysis. Accurate segmentation of breast tumours from ultrasound images is a challenging task due to the characteristics of black shadows, blurred boundaries and uneven colour intensity variations between classes. Currently, most breast tumour segmentation methods focus on extracting multi-scale information and fusing contextual information while underestimating the importance of feature information that can assist in identifying object boundaries in segmentation tasks. The loss of boundary feature information can easily lead to discontinuity or inaccuracy of the target boundary when the network generates the final prediction map. To address this problem, we propose a new feedback refinement boundary network (FRBNet) for accurate segmentation of breast tumour regions in ultrasound images, which mainly consists of a channel calibration module (CCM), boundary detection (BD) module, and feedback refinement module (FRM). Specifically, before fusing low-level feature maps with high-level feature maps, CCM first adopts the method of redistributing feature channel responses to enhance the channels carrying key target information and suppress the noisy channels in low-level feature maps. The BD module then improves the quality of the boundaries in the segmentation results by additionally learning the boundaries of breast tumours to provide accurate boundary feature information for subsequent prediction. The FRM employs a feedback mechanism that complementarily fuses the coarse prediction map and the feature map containing the target boundary feature information, thus achieving the best prediction results before generating the final prediction map. Experimental results on a public ultrasound breast dataset show that our network outperforms other medical image segmentation methods.

Could this be a lead for a solution to negative dysphotopsia?

Negative dysphotopsia (ND) was diagnosed when the mydriatic effect waned off by 4 h after intraocular lens implantation providing time for the institution of immediate rectification measures. ND was a peripheral temporal visual field defect (VFD) and manifested as a 100% black shadow having an inner arc with a sharp, smooth, and concave edge and outer border extending to the temporal periphery. ND disappeared when two fingers were kept blocking the ND over the affected side within ≤1” of the temple. The extent of VFD varied with eye movement. Clinically, intraocular lens is the cause of ND and not neuroadaptation.

Observational predictions of LQG motivated polymerized black holes and constraints from Sgr A* and M87*

Loop quantum gravity inspired partial polymer quantization in four-dimensional spacetime leads to a globally regular black hole with a single horizon. The polymerized black hole metric is characterized by the minimum length parameter k, and mimics the Schwarzschild black hole in the weak-field limit. We present an analytic and numerical investigation of the strong gravitational lensing and shadow morphology to determine the observational impacts of quantum effects. Interestingly, the light deflection angle, the angular separation between the outermost relativistic image, and magnification are significantly larger than those for the Schwarzschild black hole. Using the ray-tracing technique, we simulate the black hole shadows under three distinct optically thin accretion models: static spherical accretion, radially infalling spherical accretion, and the thin accretion disk model. Polymerized black holes' shadow morphology strongly depends on k. We derive constraints on k from the M87* and Sgr A* black hole shadow observations from the Event Horizon Telescope.

In Limbo: A Graphic Memoir by Deb JJ Lee

Reviewed by: In Limbo: A Graphic Memoir by Deb JJ Lee Kate Quealy-Gainer, Editor Lee, Deb Jj In Limbo: A Graphic Memoir; written and illus. by Deb JJ Lee. First Second, 2023 [352p] Trade ed. ISBN 9781250252654 $24.99 Paper ed. ISBN 9781250252661 $17.99 Reviewed from digital galleys R Gr. 9-12 Freshman year doesn’t begin so great for Deb: she gets teased for her Korean name, even when she insists everyone just call her Deborah, she has to endure her mother’s increasingly abusive criticisms, and she’s not doing so great in her classes. She’s looking forward to being with her friends in orchestra, but music isn’t her true passion, more of a demand by her mother. Deb’s more interested in art, and when [End Page 227] her mom signs her up for art classes and she finds a new friendship in bold and confident Quinn, things start to look up. Social dynamics change, however, and Deb’s mom’s emotional abuse escalates to physical, leading an overwhelmed Deb to attempt suicide. Fortunately, subsequent therapy and new friends and opportunities, including a visit to Seoul, help her find her footing, though she admits that her relationship with her mother will always be complex. There are few bright spots in Lee’s graphic novel memoir, and even the lighter ones have only a dull gleam, overshadowed by depression and social anxiety and making for a bleak but painfully authentic portrayal of mental illness and family trauma. That persistent despair is felt in the mostly monochromatic illustrations, with black and blue shadows constantly encroaching on the lighter elements and shifting panel structure echoing Deb’s moods. Lee’s artistic skill is undeniable, and the subtle stylistic changes add depth to both visual and emotional impact of the narrative. Readers of Krosoczka’s Hey, Kiddo (BCCB 11/18) might find this a somber counterpart that still explores the healing nature of art and its role in managing mental health and trauma. Copyright © 2023 The Board of Trustees of the University of Illinois

Sci-Hub use among Spanish researchers: Enemy or a learning opportunity for libraries?

Access to scientific literature is the cornerstone of scientific knowledge and numerous scientific-technical and social advances. However, in 2018, major difficulties in accessing the scientific literature have been reported. Despite Open Access has made more than 50% of scientific literature accessible without paywalls, during this year’s access to pirate scientific resources, such as Sci-Hub, has increased. It is one of the most popular resources among researchers and university students. The key aspect is to differentiate between these kinds of resources (black open access or shadow library) and the Open Access movement. Black open access violates copyright regulations, and Open Access wants to give authors control over the integrity of their work and the right to be properly acknowledged and cited. We conducted a questionnaire with 17 items about the use of Sci-Hub among Spanish-speaking sciences and social sciences researchers. Libraries must learn from these kinds of resources how to improve the access to their scientific resources, and propose to the editors a different way of business, more similar to Spotify or Netflix than the journal bundles offered nowadays, usually with numerous journals with an embargo period or no relevance to the scientific community.

Melanocytoma of the Optic Nerve- A Case Report

Melanocytoma of the optic disc is a benign stationary tumor that is usually pigmented, asymptomatic and stable in size. Even though benign, it can cause vision loss and visual field defect due to compression on the optic nerve. A 39-year-old male presented with a black shadow in the left eye which has been present for about 4 years. Fundus photo shows a darkly pigmented lesion of the optic nerve head of the left eye with a mild hemorrhage. B-scan ultrasonography shows a slightly elevated lesion at the optic nerve head. Fluorescein angiography shows hypofluorescence of the lesion. Optic nerve melanocytoma (ONM) may often display clinical similarities to melanoma but with adequate diagnostic tools can be distinguished from one another. ONM can either remain stable or grow progressively slowly over many years. Annual monitoring for change is highly recommended.

Effect of higher dimensions on rotating black holes shadow

The gravitation lensing features are different for gravities with the extra dimensions, hence, there is an opportunity to find the sign of extra dimension in the supermassive black hole. In new of then, we investigate the shadow cast by the higher-dimensional rotating black hole and demonstrate the higher-dimensional effect on rotating black hole shadow. The shape and size of the higher-dimensional black hole shadow is mainly characterized by its mass parameter (M), spin parameter (a) and spacetime dimensions (D). For the increasing values of the spin parameter a and spacetime dimensions D, the effective size of the black hole shadow decreases, and the shape gets more deformed. Our study includes the shadow observables in higher dimensions with the data of M87 black hole. We also calculate the energy emission rate for the higher-dimensional rotating black hole which increases with the spacetime dimensions D.

Shadow of a charged rotating black hole in f(R) gravity

We study the shadow of a charged rotating black hole in $f(R)$ gravity. This black hole is characterized by mass, $M$, spin, $a$, electric charge, $Q$ and $R_{0}$ which is proportional to cosmological constant. We analyze the image of the black hole's shadow in four types 1) at $r\rightarrow\infty$, 2) at $r\rightarrow r_{o}$, in vacuum, 3) at $r\rightarrow\infty$, 4) at $r\rightarrow r_{o}$, for an observer at the presence of plasma. Moreover, we investigate the effect of spin, charge and modfication of gravity on the shape of shadow. In addition, we use two observables, the radius $R_{s}$ and the distortion parameter $\delta_{s}$, characterizing the apparent shape. We show that for all cases, the shadow becomes smaller with increasing electric charge. Also, by increasing the rotation parameters, circular symmetry of the image of black hole's shadow will change. Furthermore, in the presence of plasma, plasma parameter also effects on size of the shadow.

Akute Sehstörungen bei Diabetes

Interdisciplinary treatment is needed in the management of diabetes. Diabetic retinopathy is the leading cause of preventable blindness in the working age population in industrialised countries. By asking brief questions, the internist can better assess various visual disorders that a patient may have. In this way, foggy vision can be distinguished from dark spots or black shadows. The internist can thus make better recommendations as to when presentation to the ophthalmologist should take place. When appropriate, prompt presentation to an ophthalmologist allows the necessary ophthalmological treatment to take place earlier in time-critical cases.

On the shearing mechanisms of β" precipitates by the dislocations gliding on the {100}Al planes in Al–7Si–Mg alloys

In this study, some deformation and shear behaviors of the β" phase in Al–7Si–Mg alloy were found to be caused by the dislocations on {100}Al planes instead of {111}Al planes. Corresponding shearing mechanisms were systematically investigated by combing high-resolution transmission electron microscopy (HRTEM) and first-principles calculations. All the possible shearing process on the {100}Al planes, such as the shearing along the cross-section, the width, and the length of the needle has been considered and studied. The optimal atomic slip layers and the energetically most favorable paths were obtained by the generalized-stacking-fault energy (GSFE) curves. It was found that, for the shearing along the (100)β'' and (001)β'' planes, the cross planes at the middle of the Si2 pillars in the β" phase are the easiest slip planes. This can be attributed to the lowest energy barriers and the destruction and recombination of Mg–Si and Si–Si covalent bonds near the slip planes during shearing. Based on these conclusions, the formation mechanisms of the black trailing shadows and the step-like morphology in the deformed β" phase can be well explained. These findings provide a deeper understanding of the deformation and shear behavior of β" precipitates.

Five dimensional rotating regular black holes and shadow

Higher-dimensional theories admit that astrophysical objects like supermassive black holes are somewhat different from standard ones and that their optical properties deviate from general relativity. A black hole casts a shadow as an optical appearance because of its strong gravitational field, and a black hole shadow could be used to determine which theory of gravity is consistent with observations. Measurements of the shadow sizes around the black holes can help evaluate various parameters of the black hole metric and may provide an opportunity to find signatures of extra dimensions. We present an exact five-dimensional (5D) rotating regular black hole metric, with a deviation parameter \(k\ge 0\), that interpolates between the 5D Kerr black hole (\(k=0\)) and 5D Kerr–Newman (\(r \gg k\)). This 5D rotating regular black hole is an exact general relativity solution coupled to nonlinear electrodynamics. Interestingly, for a given value of parameter k, there exits a critical angular momentum \(a=a_E\), which corresponds to an extremal rotating regular black hole with degenerate horizons. At the same time, for \(a<a_E\), one has a non-extremal rotating regular black hole with outer and inner horizons. Owing to the correction factor (\(e^{-k/r^2}\)), which is motivated by the quantum arguments, the ergoregion and shadow of 5D black holes are modified.

THOLPAVAKOOTHU:A STUDY ON THE PERFORMING ART OF SHADOW PUPPETRY IN KERALA

Tholpavakoothu is a form of shadow puppetry which is the ancient art form found only in Kerala and it is a ritualistic worship for Goddess Devi. The main theme of tholpavakoothu is based on Kamba Ramayan and puppets which are chiseled out beautifully on the animal skin are used for the puppetry. Unlike other puppetry, it is the black shadow of puppets that forms on the white screen in the presence of oil lamps that portrays the tale of Ramayana. The study is for the deeper understanding of the origin, style, forms, and themes of tholpavakoothu and also to find out the different influences of applied puppetry in tholpvakoothu. This study uses a qualitative approach using interviews with the artists and performances. It has given a deeper understanding of the uniqueness of tholpavakoothu compared to other puppetry forms. This form basically emphasizes the concepts of mythology and how the form has taken a transition to contemporary issues to cater to all types of audiences.

Features of municipal-level election campaigns in the capitals of the Tver, Belgorod and Kostroma regions

The article deals with the peculiarities of the course of election campaigns in the municipal representative bodies of the cities of Tver and Kostroma. The article is part of a larger study on the peculiarities of the course of election campaigns in the capitals or administrative centers of the subjects of the Russian Federation in the Central Federal District, which focuses on the problems of three subjects and compares the research material from these subjects with general district trends and features. Tver, Belgorod and Kostroma represent a wide geographical range and three peculiar examples of the course of election campaigns in large municipalities. The study revealed such common features as low turnout, rather weak competitiveness, the use of black PR and other shadow technologies, the traditional representation of lobbying structures in municipal parliaments, as well as the mobilization of "parliamentary opposition parties" and small parties at the last election campaigns in the elections of the type we study. The article acquires particular importance within the framework of the work of the State Duma of the Federal Assembly of the Russian Federation (and subsequent legislative instances) on Draft Law No. 1256381-7 «On general principles of the organization of public power in the subjects of the Russian Federation», where special attention is supposed to be attributed to the order of election and aspects of regulation of the work of municipal parliaments of the capitals of the subjects of the Russian Federation.