Dark Background Research Articles

Relativistic Exploration of Dark Matter Effectsin Rotating Galaxy, Studied Fluid-Dynamically

Galactic space is filled with interstellar clouds of neutral gases. Motion of the space-clouds is viewed as a flow of continuous fluid in curved space with gravity. Dynamical motions of the space-fluid of rotating galaxies are investigated by extending Fluid Dynamics to that in the frame of general relativity. Fluid flow field to be extended to that of a relativistic theory is reinforced by the fluid gauge theory equipped with a background (dark) gauge field conditioning the fluid continuity. The Gravity-space Fluid Dynamics thus developed captures main feature of the dark-matter effect as the action of the gauge field on the motion of space fluids. In the present formulation, the stress-energy tensor in the general relativity is revised in order to take account of general nature of stress field by extending the isotropic pressure to an-isotropic stress field.

Colour shade and chemical influences on the capture of adults Frankliniella occidentalis (Thysanoptera: Thripidae) in blackberry crops

AbstractWestern flower thrips (WFT) are a major pest for blackberry crops in Mexico, causing economic damage. To monitor this pest, yellow and blue sticky traps are commonly used during the blossom season. However, the impact of different shades of yellow and blue on adult WFT capture has not been well understood. The study tested different shades of yellow and blue to determine their influence on capturing of Frankliniella occidentalis in infested blackberry crops. Additionally, diverse geometric shapes in bright blue (the most appealing shade from the initial test) set against a dark green backdrop were examined. Furthermore, the potential synergy between the bright blue sticky traps and commercial attractants was investigated. Bright blue (blue 3; 59% reflectance to 548 nm) and fluorescent yellow (yellow 4; 98% reflectance to 522 nm) traps were effective in capturing adult WFT in high numbers, however, the bright blue traps displayed a numerical superiority (5.6%–12.8% more) over the fluorescent yellow traps. Furthermore, the introduction of various geometric shapes in bright blue against a dark green background showed a significant effect on the capture of adult WFT, with the traps consisting of a triangle and the semicircle yielding the highest captures (standardized data with respect to the blue area of the trap). However, the results indicate that a trap without contrast (>blue area) can be used if it is placed in contrast to the crop foliage (non‐standardized data). Lurem‐TR, a commercial attracts, significantly increased adult WFT capture rates, doubling or tripling the capture to traps without bait, and 2 mg of eugenol increased captures by 1.5–2.5 times. The findings are crucial for improving the monitoring and control of WFT blackberry crops. By optimizing trapping strategies, the agricultural sector can better manage the impact of this pest on blackberry cultivation.

Latent fingerprint detection using fluorescent powder dusting technique

This study examined the use of fluorescent powder in detecting latent fingerprints through the dusting method. Five colors of fluorescent powder (orange, green, blue, green-yellow, and red) were applied to photo papers of six colors (green, red, blue, yellow, white, and black). The fluorescence of latent fingerprints was detected using various light sources including UV LED, blue LED, green LED, red LED, warm white, and cold white. The spectra of the light source and the fluorescence intensity of the dusting powder were analyzed to determine their influence on the appearance of latent fingerprints. The fingerprint images were analyzed by counting the number of important points that are more than 7 points, which indicates visible fingerprints. The results showed that the fluorescence of the powder, background, and light source affected the appearance of the fingerprints. When the color of the fluorescent powder matched the color of the light source, the fingerprints were clearly visible. However, if the background color matched the light source, the fingerprints were not visible. When fluorescent powder was dusted on a dark or non-fluorescent background, fingerprints were visible under all light sources. This study suggests that selecting the appropriate color of fluorescent powder and background is crucial for the detection of latent fingerprints using the dusting method.

Revisiting coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds

Massive neutrinos are well-known to cause a characteristic suppression in the growth of structures at scales below the neutrino free-streaming length. A detailed understanding of this suppression is essential in the era of precision cosmology we are entering into, enabling us to better constrain the total neutrino mass and possibly probe (beyond)-ΛCDM cosmological model(s). Instead of the usual N-body simulation or Boltzmann solver, in this article we consider a two-fluid framework at the linear scales, where the neutrino fluid perturbations are coupled to the CDM (+ baryon) fluid via gravity at redshifts of interest. Treating the neutrino mass fraction f ν as a perturbative parameter, we find solutions to the system with redshift-dependent neutrino free-streaming length in ΛCDM background via two separate approaches. The perturbative scale-dependent solution is shown to be in excellent agreement with numerical solution of the two-fluid equations valid to all orders in f ν, and also agrees with results from CLASS to a good accuracy. We further generalize the framework to incorporate different evolving dark energy backgrounds and found sub-percent level differences in the suppression, all of which lie within the observational uncertainty of BOSS-like surveys. We also present a brief discussion on the prospects of the current analysis in the context of upcoming missions.

Designing and Implementing a Dark Mode for a Library Website

Dark mode, also known as night mode, is an alternative way of viewing content on a webpage. Rather than having dark text on a light background, dark mode displays light text on a dark background. In fall 2022, the Indiana University–Purdue University Indianapolis (IUPUI) University Library launched a dark mode as an option for web users. We present some considerations for design and implementation for those interested in adding a dark mode to their website.

CP-violating axion interactions II: axions as dark matter

Axions provide a solution to the strong CP problem and are excellent dark matter candidates. The presence of additional sources of CP violation, for example to account for the matter/antimatter asymmetry of the universe, can lead to CP-violating interactions between axions and Standard Model fields. In case axions form a coherent dark matter background, this leads to time-oscillating fundamental constants such as the fine-structure constant and particle masses. In this work we compare the sensitivity of various searches for CP-odd axion interactions. These include fifth-force experiments, searches for time-oscillating constants induced by axion dark matter, and direct limits from electric dipole moment experiments. We show that searches for oscillating constants can outperform fifth-force experiments in the regime of small axion masses, but, in general, do not reach the sensitivity of electric dipole moment experiments.

Many-Exciton Quantum Dynamics in a Ruddlesden-Popper Tin Iodide.

We present a study on the many-body exciton interactions in a Ruddlesden-Popper tin halide, namely, (PEA)2SnI4 (PEA = phenylethylammonium), using coherent two-dimensional electronic spectroscopy. The optical dephasing times of the third-order polarization observed in these systems are determined by exciton many-body interactions and lattice fluctuations. We investigate the excitation-induced dephasing (EID) and observe a significant reduction of the dephasing time with increasing excitation density as compared to its lead counterpart (PEA)2PbI4, which we have previously reported in a separate publication [J. Chem. Phys.2020, 153, 164706]. Surprisingly, we find that the EID interaction parameter is four orders of magnitude higher in (PEA)2SnI4 than that in (PEA)2PbI4. This increase in the EID rate may be due to exciton localization arising from a more statically disordered lattice in the tin derivative. This is supported by the observation of multiple closely spaced exciton states and the broadening of the linewidth with increasing population time (spectral diffusion), which suggests a static disordered structure relative to the highly dynamic lead-halide. Additionally, we find that the exciton nonlinear coherent lineshape shows evidence of a biexcitonic state with low binding energy (<10 meV) not observed in the lead system. We model the lineshapes based on a stochastic scattering theory that accounts for the interaction with a nonstationary population of dark background excitations. Our study provides evidence of differences in the exciton quantum dynamics between tin- and lead-based Ruddlesden-Popper metal halides (RPMHs) and links them to the exciton-exciton interaction strength and the static disorder aspect of the crystalline structure.

Religion in Begum Rokeya’s Literature: Resemblance with the Marxist Narrative

Against the dark background of the social exclusion of women, especially Muslim women, Begum Rokeya, the pioneer of women’s emancipation in Bengal, British India in the early 20th century, stood with her enlightenment like a beacon and pushed her way for women’s emancipation from the depths of misery. She lived in a society shrouded by blind religious beliefs and practices where women were deprived of rights and freedom, and were repressed and oppressed in the name of religion. Despite her prevailing leanings toward religious beliefs and practices, she found that a powerful obstacle to women’s freedom stemmed from the misinterpretation of culturally biased religious norms, notions and intentions. She was a strong advocate for the emancipation of the society and especially women of her time. She eloquently expressed her opinion with regard to religious rituals, prevailing sentiments and general public psyche in practice that hindered the progress and emancipation of women as well as the society. Her opinions, propositions, criticisms, and activisms in this regard surprisingly resembled to a great extent that of the predominant Marxist views. In this article, her views and opinions on the dissemination and practice of religious teachings and rituals in the context of the marginalization of women as well as society have been examined and compared with that of the Marxist thoughts, especially those on religion through textual analysis and Marxist allusions.

The effect of aquarium color background on the survival, growth performance, body coloration, and enzymatic activity of laboratory cultured Cherax quadricarinatus juveniles

The effect of different background colors (red, yellow, blue, green, white, and black) on crayfish Cherax quadricarinatus juveniles was evaluated over a 50-day rearing period. Survival, growth, body color, and enzymatic activity were assessed. At the experiment's conclusion, survival, growth, and weight were calculated. Body color was analyzed using Lab color composition, and enzyme activities (amylase, lipase, superoxide dismutase, catalase) were assessed in the dissected hepatopancreas. Results showed no effect of background color on survival rate (P > 0.05). However, crayfish reared against black and red backgrounds exhibited significantly higher weight, growth rate, and condition factor compared to those on white and yellow backgrounds (P < 0.05). Background color also influenced body color, with deeper coloration observed on claws, tail, and abdomen against white, yellow, green, red, black, and blue backgrounds. Crayfish on white and yellow backgrounds showed similar coloration (ΔE = 1.69), in contrast to specimens cultured against the blue background (ΔE = 23.94). The amylase (AMS) activity varied, with the highest in black backgrounds and the lowest in blue. Lipase (LPS) activity did not differ significantly except for lower activity in the blue and green background. Superoxide dismutase (SOD) activity was highest in the red background and lowest in the green background. Catalase (CAT) activity varied significantly, with the highest in red and black groups and inhibitory activity in green. Further research is needed to understand the underlying mechanisms behind enzymatic activity variations due to background color. The effect of environmental conditions on body color modification should be considered in C. quadricarinatus juvenile culture. Dark backgrounds are recommended for growth, while light backgrounds should be avoided.

Dark background–surface enhanced Raman spectroscopic detection of nanoplastics: Thermofluidic strategy

This study aims to develop a cost-effective and time-efficient method for detecting nanoplastics, which have recently garnered significant attention due to their potential harmful impact on the water environment (XiaoZhi, 2021; Gigault et al., 2021; Mitrano et al., 2021; Ferreira et al., 2019). Although several techniques are available to accumulate data on microplastics, there is currently no universally accepted analytical technique for detecting nanoplastics (Gigault et al., 2021; Mitrano et al., 2021; Mitrano et al., 2019; Cai et al., 2021a; Allen et al., 2022). In this study, we have developed a substrate that exhibits Surface-enhanced Raman scattering (SERS) (Zhou et al., 2021; Lv et al., 2020; Lê et al., 2021; Hu et al., 2022; Chang et al., 2022; Yang et al., 2022; Xu et al., 2020; Jeon et al., 2021; Lee and Fang, 2022; Vélez-Escamilla and Contreras-Torres, 2022; Liu et al., 2022; Xie et al., 2023) activity over a large area and a dark background in optical (darkfield mode) vision, enabling the detection of sparkling nanoplastics on the substrate. This darkfield-based strategy allows for the point-by-point detection of single nanoplastics, offering cost and time-saving advantages over other resource-intensive analytical techniques. Our findings reveal the presence of PP nanoplastics in commonly used laboratory equipment, individual PE nanoplastics from a hot water-contained commercial paper cup, and the first detection of natural nanoplastics in coastal seawater. We believe that this technique will have a universal application in establishing a global map of nanoplastics and advancing our understanding of the environmental life cycle of plastics.

Seeing color following gene augmentation therapy in achromatopsia

How will people who spent their visual lives with only rods respond to cone function restoration? Will they be able suddenly see the colors of the rainbow? CNGA3-achromatopsia is a congenital hereditary disease in which cone dysfunction leads patients to have rod photoreceptor-driven vision only in daylight,1,2,3,4 seeing the world in blurry shades of gray.5,6 We studied color perception in four CNGA3-achromatopsia patients following monocular retinal gene augmentation therapy.7,8,9 Following treatment, although some cortical changes were reported,3,4 patients did not report a dramatic change in their vision.3,9 However, in accordance with the fact that sensitivity of rods and cones is most different at long wavelengths, they consistently reported seeing red objects on dark backgrounds differently than they did before surgery.3 Because clinical color assessments failed to find any indication of color vision, we conducted a gamut of tailored tests to better define patients' descriptions. We evaluated patients' perceived lightness of different colors, color detection, and saliency, comparing their treated with their untreated eyes. Although the perceived lightness of different colors was generally similar between the eyes and matched a rod-input model, patients could detect a colored stimulus only in their treated eyes. In a search task, long response times, which were further extended with array size, suggested low saliency. We suggest that treated CNGA3-achromatopsia patients can perceive a stimulus's color attribute, although in a manner that is different and very limited compared with sighted individuals. We discuss the retinal and cortical obstacles that might explain this perceptual gap.

Seeing in the dark: Challenges in the interpretation of x‐ray fluorescence element distribution maps associated with black paints

AbstractDuring the conservation of easel paintings, black draperies or dark backgrounds often prove problematic to treat and understand in terms of condition. Despite most black pigments in Old Master paintings not intrinsically containing high atomic number elements, the investigation of black paints is one of the National Gallery's major uses and most helpful applications of x‐ray fluorescence (XRF) scanning. As a visual tool, XRF element distribution maps of black paints are useful for assessing the extent of overpainting or condition of any surviving original paint beneath, and for revealing the original modelling. However, interpreting the XRF element maps can be challenging. It is important to consider not only the primary compositions of black or dark pigments, but to have an understanding of other possible associated materials and more broadly of historical painting techniques, artists' practices and the paint stratigraphy. Through a series of case studies, this paper demonstrates how a detailed knowledge of historic painting materials and techniques, based on study of documentary sources and archives of materials‐based evidence from the analysis of paint cross‐sections—both from the paintings being studied and related works—aids and enriches interpretation of XRF element maps of black paints. While samples are invaluable in understanding exactly how—and with what materials—such regions were painted, they are not always representative and scanning XRF may be of complementary benefit in providing a more holistic view of pigment distribution. The examples presented range from the fifteenth to the seventeenth century from both Northern Europe and Italy.

Stripe segmentation of oceanic internal waves in SAR images based on Gabor transform and K-means clustering

Oceanic internal waves are an active ocean phenomenon that can be observed, and their relevant characteristics can be acquired using synthetic aperture radar (SAR). The locations of oceanic internal waves must be determined first to obtain the important parameters of oceanic internal waves from SAR images. An oceanic internal wave segmentation method with integrated light and dark stripes was described in this study. To extract the SAR image characteristics of oceanic internal waves, the Gabor transform was initially used, and then the K-means clustering algorithm was used to separate the light (dark) stripes of oceanic internal waves from the background in the SAR images. The regions of the dark (light) stripes were automatically determined based on the differences between the three classes, that is, the dark stripes, light stripes, and background area. Finally, the locations of the dark (light) stripes were determined by shifting a given distance along the normal direction of the long side with the minimum bounding rectangle of the light (dark) stripes. The best segmentation results were obtained based on the intersection over the union of the images, and the accuracy of segmentation was verified. Furthermore, the effectiveness and practicability of the proposed method in the light and dark stripe segmentation of SAR images of oceanic internal waves were illustrated. The proposed method prepares the foundation for future inversion studies of oceanic internal waves.

Tritium beta decay with modified neutrino dispersion relations: KATRIN in the dark sea

We explore beta decays in a dark background field, which could be formed by dark matter, dark energy or a fifth force potential. In such scenarios, the neutrino's dispersion relation will be modified by its collective interaction with the dark field, which can have interesting consequences in experiments using tritium beta decays to determine the absolute neutrino mass. Among the most general interaction forms, the (pseudo)scalar and (axial-)vector ones are found to have interesting effects on the spectrum of beta decays. In particular, the vector and axial-vector potentials can induce distinct signatures by shifting the overall electron energy scale, possibly beyond the usually defined endpoint. The scalar and pseudoscalar potentials are able to mimic a neutrino mass beyond the cosmological bounds. We have placed stringent constraints on the dark potentials based on the available experimental data of KATRIN. The sensitivity of future KATRIN runs is also discussed.

Artificial light at night causes conflicting behavioural and morphological defence responses in a marine isopod.

Encroachment of artificial light at night (ALAN) into natural habitats is increasingly recognized as a major source of anthropogenic disturbance. Research focussed on variation in the intensity and spectrum of ALAN emissions has established physiological, behavioural and population-level effects across plants and animals. However, little attention has been paid to the structural aspect of this light, nor how combined morphological and behavioural anti-predator adaptations are affected. We investigated how lighting structure, background reflectance and the three-dimensional properties of the environment combined to affect anti-predator defences in the marine isopod Ligia oceanica. Experimental trials monitored behavioural responses including movement and background choice, and also colour change, a widespread morphological anti-predator mechanism little considered in relation to ALAN exposure. We found that behavioural responses of isopods to ALAN were consistent with classic risk-aversion strategies, being particularly exaggerated under diffuse lighting. However, this behaviour was disconnected from optimal morphological strategies, as diffuse light caused isopods to become lighter coloured while seeking out darker backgrounds. Our work highlights the potential for the structure of natural and artificial light to play a key role in behavioural and morphological processes likely to affect anti-predator adaptations, survival, and ultimately wider ecological effects.

Effects of Stimulus Luminance, Stimulus Color and Intra-Stimulus Color Contrast on Visual Field Mapping in Neurologically Impaired Adults Using Flicker Pupil Perimetry.

We improve pupillary responses and diagnostic performance of flicker pupil perimetry through alterations in global and local color contrast and luminance contrast in adult patients suffering from visual field defects due to cerebral visual impairment (CVI). Two experiments were conducted on patients with CVI (Experiment 1: 19 subjects, age M and SD 57.9 ± 14.0; Experiment 2: 16 subjects, age M and SD 57.3 ± 14.7) suffering from absolute homonymous visual field (VF) defects. We altered global color contrast (stimuli consisted of white, yellow, cyan and yellow-equiluminant-to-cyan colored wedges) in Experiment 1, and we manipulated luminance and local color contrast with bright and dark yellow and multicolor wedges in a 2-by-2 design in Experiment 2. Stimuli consecutively flickered across 44 stimulus locations within the inner 60 degrees of the VF and were offset to a contrasting (opponency colored) dark background. Pupil perimetry results were compared to standard automated perimetry (SAP) to assess diagnostic accuracy. A bright stimulus with global color contrast using yellow (p=0.009) or white (p=0.006) evoked strongest pupillary responses as opposed to stimuli containing local color contrast and lower brightness. Diagnostic accuracy, however, was similar across global color contrast conditions in Experiment 1 (p=0.27) and decreased when local color contrast and less luminance contrast was introduced in Experiment 2 (p=0.02). The bright yellow condition resulted in highest performance (AUC M =0.85±0.10, Mdn=0.85). Pupillary responses and pupil perimetry's diagnostic accuracy both benefit from high luminance contrast and global but not local color contrast.

Synthesis of ZnO nanoparticles by precipitation method: Characterizations and applications in decipherment of latent fingerprints

Here in we present the synthesis of phase pure ZnO nanoparticles using precipitation method. X-ray Diffraction (XRD) and UV–Visible spectroscopy were used to characterize the synthesized ZnO nanoparticles. The observed data is in good agreement with previously reported XRD data of ZnO nanoparticles (JCPDS File number 36–1451) which confirms the synthesis of pure phase ZnO nanoparticles. Scherrer formula was used to calculate the crystallite size of the synthesized ZnO nanoparticles. The band gap of synthesized Zinc oxide nanoparticles was obtained using UV–Visible spectroscopy. We used these ZnO nanoparticles’ powder for latent fingerprint (LFP) development. The developed fingerprints were tape lifted using normal cellophane tape and was pasted over a dark background surface. Photography was done before and after the lifting process and was sticked over a dark surface.

Melanin-Integrated Structural Color Hybrid Hydrogels for Wound Healing.

Hydrogel patches have outstanding values in wound treatment; challenges in this field are concentrated on developing functional and intelligent hydrogel patches with new antibacterial strategies for improving healing process. Herein, a novel melanin-integrated structural color hybrid hydrogel patches for wound healing is presented. Such hybrid hydrogel patches are fabricated by infusing asiatic acid (AA)-loaded low melting-point agarose (AG) pregel into the melanin nanoparticles (MNPs)-integrated fish gelatin inverse opal film. In this system, MNPs not only impart the hybrid hydrogels with properties of photothermal antibacterial and antioxidant, but also improve the visibility of structural colors by providing an inherent dark background. Besides, the photothermal effect of MNPs under near-infrared irradiation can also trigger liquid transformation of AG component in hybrid patch, resulting in the controllable release of its loaded proangiogenic AA. Attracting, this drug release induced refractive index variations in the patch can be detected as visible structural color shifting, which can be used to monitor their delivery processes. Benefiting from these features, the hybrid hydrogel patches are demonstrated to achieve excellent therapeutic effects for in vivo wound treatment. Thus, it is believed that the proposed melanin-integrated structural color hybrid hydrogels are valuable as multifunctional patches for clinical applications.

Asymmetric presentation with a novel RP2 gene mutation in X-Linked retinitis pigmentosa: a case report

BackgroundWe present the detailed multimodal imaging analysis in a case of X-linked retinitis pigmentosa (XLRP) exhibiting a markedly asymmetric presentation with a novel RP2 mutation.Case presentationA 25-year-old woman complained of decreased vision in the right eye as well as night blindness. Her visual acuity was 20/100 (OD) and 20/20 (OS). Fundus examination revealed bone spicule pigmentation with tessellated changes in the fundus within the posterior pole. Optical coherence tomography (OCT) showed generalized disruption of foveal microstructures in the OD. No abnormal findings were identified, but localized ellipsoid zone band losses were observed on OCT in the OS. Fundus autofluorescence revealed multiple patchy hypo-autofluorescent lesions in the OD and a tapetal-like radial reflex against a dark background in the OS. Fluorescein angiography and OCT angiography revealed diffuse mottled hyperfluorescence with reduced retinal vessel density in the OD and no evidence of vascular compromise in the OS. Goldmann perimetry demonstrated a constricted visual field, and electrophysiological assessment revealed an extinguished rod response and a severely impaired cone response in the OD. Molecular genetic tests via next-generation sequencing revealed the pathogenic variant to be a heterozygous frameshift mutation in RP2 (RP2, p.Glu269Glyfs*7), resulting in premature termination of the protein.ConclusionsRandom X-inactivation may be attributed to interocular differences in the severity of XLRP in female carriers. A novel frameshift mutation in the RP2 gene and a comprehensive phenotypic evaluation in the current study may broaden the spectrum of the disease in XLRP carriers.

Final Color of CAD-CAM Produced Thin Lithium Disilicate Ceramics Cemented with Different Colored Resin Cements on Darker Backgrounds

Aim: The aim of the present study was to evaluate the final color of CAD-CAM produced thin lithium disilicate ceramics cemented with A2, opaque, and bleach resin cements on darker backgrounds. Materials and Method: Nine different experimental groups (n=10) were generated according to the colors of resin backgrounds (ND3:A3, ND4:A3.5, and ND8:A4) and cements (A2, opaque, and bleach). Target specimen was prepared by cementing lithium disilicate ceramic layer onto ND2 (A2) background by using translucent resin cement. The color difference values between experimental groups and target specimen were calculated according to CIEDE2000 formula. The data were statistically analyzed by using Kruskall Wallis test (α=0.05). Results: The results showed that most of the experimental groups had higher color difference values than acceptability threshold (1.8) except ND3-A2 and ND3-opaque groups. It was observed that when the background got darker, the color difference values increased. Conclusion: The darker backgrounds (A3, A3.5, and A4) and resin cement color (A2, opaque, and bleach) affected the final color of the lithium disilicate ceramics in 1 mm thickness. Color difference values were found in clinically acceptable limits for cementing lithium disilicate ceramics with A2 and opaque resin cements on A3 background.