The deep-sea is the largest and one of the dimmest habitats on earth. In this extreme environment, every photon counts and may make the difference between life and death for its inhabitants. Two ...sources of light are present in the deep-sea; downwelling light, that becomes dimmer and spectrally narrower with increasing depth until completely disappearing at around 1000 m, and bioluminescence, the light emitted by animals themselves. Despite these relatively dark and inhospitable conditions, many teleost fish have made the deep-sea their home, relying heavily on vision to survive. Their visual systems have had to adapt, sometimes in astonishing and bizarre ways. This review examines some aspects of the visual system of deep-sea teleosts and highlights the exceptional diversity in both optical and retinal specialisations. We also reveal how widespread several of these adaptations are across the deep-sea teleost phylogeny. Finally, the significance of some recent findings as well as the surprising diversity in visual adaptations is discussed.
Dim light melatonin onset, or the rise in melatonin levels representing the beginning of the biological night, is the gold standard indicator of circadian phase. Considerably less is known about dim ...light melatonin offset, or the decrease in melatonin to low daytime levels representing the end of the biological night. In the context of insufficient sleep, morning circadian misalignment, or energy intake after waketime but before dim light melatonin offset, is linked to impaired insulin sensitivity, suggesting the need to characterize dim light melatonin offset and identify risk for morning circadian misalignment.
We examined the distributions of dim light melatonin offset clock hour and the phase relationship between dim light melatonin offset and waketime, and associations between dim light melatonin offset, phase relationship, and chronotype in healthy adults (N = 62) who completed baseline protocols measuring components of the circadian melatonin rhythm and chronotype.
74.4% demonstrated dim light melatonin offset after waketime, indicating most healthy adults wake up before the end of biological night. Later chronotype (morningness-eveningness, mid-sleep on free days corrected, and average mid-sleep) was associated with later dim light melatonin offset clock hour. Later chronotype was also associated with a larger, positive phase relationship between dim light melatonin offset and waketime, except for morningness-eveningness.
These findings suggest morning circadian misalignment risk among healthy adults, which would not be detected if only dim light melatonin onset were assessed. Chronotype measured by sleep timing may better predict this risk in healthy adults keeping a consistent sleep schedule than morningness-eveningness preferences. Additional research is needed to develop circadian biomarkers to predict dim light melatonin offset and evaluate appropriate dim light melatonin offset timing to promote health.
Infrared (IR) dim and small target detection in a highly complex background play an important role in many applications, and remain a challenging problem. In this paper, a novel method named stable ...multisubspace learning is presented to deal with this problem. The new method takes into account the inner structure of actual images so that it overcomes the shortage of the traditional method. First, by analyzing the multisubspace structure of heterogeneous background data, a corresponding image model is proposed using subspace learning strategy. This model is also stable to noise interference. Second, an efficient optimization algorithm is designed to solve the proposed IR image model. By adding the proper postprocessing procedure, we can get the detection result. Experiments on simulation scenes and real scenes show that the proposed method has superior detection ability under heterogeneous background.
Light at night (LAN) negatively impacts the behaviour and physiology; however, very little is known about molecular correlates of LAN-induced effects in diurnal animals. Here, we assessed LAN-induced ...effects on behaviour and physiology, and examined molecular changes in the liver of diurnal zebra finches (Taeniopygia guttata). Birds were exposed to dim LAN (dLAN: 12L = 150 lux: 12D = 5 lux), with controls on 12L (150 lux): 12D (0 lux). dLAN altered daily activity-rest and eating patterns, induced nocturnal eating and caused body fattening and weight gain, and reduced nocturnal melatonin levels. Concomitant increased nighttime glucose levels, decreased daytime thyroxine and triglycerides levels, and hepatic lipid accumulation suggested the impairment of metabolism under dLAN. Transcriptional assays evidenced dLAN-induced negative effects on metabolism in the liver, the site of metabolic homeostasis. Particularly, increased g6pc and foxo1 mRNA expressions suggested an enhanced gluconeogenesis, while increased egr1 and star expressions suggested enhanced cholesterol biosynthesis and lipid metabolism, respectively. Similarly, overexpressed sirt1 indicated protection from the metabolic damage due to elevated gluconeogenesis and cholesterol biosynthesis under dLAN. However, no effect on genes involved in lipogenesis (fasn) and insulin signalling pathway (socs3 and insig1) might indicate for the post transcriptional/post translational modification effects or the involvement of other genetic pathways in LAN-induced effects. We also found daily rhythm in the hepatic expression of selected clock and clock-controlled genes (per2, bmal1 and reverb-beta), with an elevated mesor and amplitude of per2 oscillation, suggesting a role of per2 in the liver metabolism. These results demonstrate dLAN-induced negative effects on the behaviour and physiology, and provide molecular insights into metabolic risks of the exposure to illuminated nights to diurnal animals including humans in an urban setting.
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•Dim Light at night (dLAN) negatively impacts diurnal behaviour and physiology.•dLAN caused fattening, weight gain and lipid accumulation in liver of zebra finches.•Increased glucose and decreased thyroxine and nocturnal melatonin levels under dLAN.•dLAN altered transcription of genes involved in carbohydrate and fat metabolism.•An illuminated night imposes health risks to diurnal animals in an urban setting.
Purpose The aim of this study was to compare subjective refraction under two lighting conditions to understand whether illumination affects the correction of myopia. Patients and methods This is a ...prospective, comparative study that was carried out on 33 myopic patients with corrected visual acuity of both eyes of 1.0 or better (in decimal unit). The included patients had a refractive error greater than −1.50 D. Examinations were carried out under two levels of lighting conditions. The patients underwent objective refraction followed by subjective refraction, pupil diameter measurement, visual acuity assessment, and intraocular pressure measurement. Results The mean subjective refraction under room illumination at 2, 4, and 6 m was −0.65, −0.48, and +0.29 D, respectively, compared with −0.42, +0.39, and +0.60 D without room illumination, respectively. There was a statistically significant difference between mean value of subjective refractions under the two lighting conditions at 4 m (P=0.00) and 6 m (P=0.00). However, the mean subjective refraction at the distance of 2 m was not statistically significantly different between the two lighting conditions (P=0.25). At 2 m, the pupil size and subjective refraction did not show significant differences under both lighting conditions (with and without room illumination). Conclusion There was a hyperopic refractive shift during subjective refraction in dim illumination, which may cause undercorrection of myopia that may trigger myopia progression.
The detection of infrared small targets under low signal-to-clutter ratio (SCR) and complex background conditions has been a challenging and popular research topic. In this article, a ...spatial-temporal feature-based detection framework is proposed. First, several factors, such as the infrared target's small sample, the sensitive size, and the usual sample selection strategy, that affect the detection of small targets are analyzed. In addition, the small intersection over union (IOU) strategy, which helps to solve the false convergence and sample misjudgment problem, is proposed. Second, aiming at the difficulties due to the target's dim information and complex background, the interframe energy accumulation (IFEA) enhancement mechanism-based end-to-end spatial-temporal feature extraction and target detection framework is proposed. This framework helps to enhance the target's energy, suppress the strong spatially nonstationary clutter, and detect dim small targets. Experimental results show that using the small IOU strategy and IFEA mechanism, the proposed multiple frame-based detection framework performs better than some popular deep learning (DL)-based detection algorithms.
In this paper, new exact solitary wave, soliton and elliptic function solutions are constructed in various forms of three dimensional nonlinear partial differential equations (PDEs) in mathematical ...physics by utilizing modified extended direct algebraic method. Soliton solutions in different forms such as bell and anti-bell periodic, dark soliton, bright soliton, bright and dark solitary wave in periodic form etc are obtained, which have large applications in different branches of physics and other areas of applied sciences. The obtained solutions are also presented graphically. Furthermore, many other nonlinear evolution equations arising in mathematical physics and engineering can also be solved by this powerful, reliable and capable method. The nonlinear three dimensional extended Zakharov-Kuznetsov dynamica equation and (3+1)-dimensional modified KdV-Zakharov-Kuznetsov equation are selected to show the reliability and effectiveness of the current method.
The goal of infrared and visible image fusion is to generate an integrated image which can simultaneously preserve more visible detail information and prominent information from the input images. In ...order to achieve this goal, a novel infrared and visible fusion method based on visual saliency sparse representation and detail injection model (DIM) is presented. The proposed fusion method contains four steps. The first step is to decompose the source images into base layers and detail layers through the proposed multiscale decomposition method, which has the advantages of scale awareness and high-edge-preservation efficiency. Then, we design a novel subfusion rule called visual saliency sparse representation to get the fused base layer. Third, a DIM is developed to fuse the detail layers. In this model, we first employ a "max-absolute" scheme to obtain prefused images, which are then used as the model items for participating in the fusion process of the detail layers. Finally, the target-merged image is achieved through an inverse multiscale decomposition method. The experimental results demonstrate that the proposed method can not only preserve the details and significant information of source images but also enhance the brightness of the fused image, when compared to other state-of-the-art fusion methods.
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