Light reflectance
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This paper describes a compact video-ophthalmoscope (VO) designed for capturing retinal video sequences of the optic nerve head (ONH) under flicker light stimulation. The device uses an OLED display and a fiber optic-coupled LED light source, enabling high-frame-rate video at low illumination intensity (12 μW/cm2). Retinal responses were recorded in 10 healthy subjects during flicker light exposure with a pupil irradiance of 2 μW/cm2. Following 20 s of stimulation, all subjects displayed changes in retinal reflectance and pulsation attenuation, linked to blood flow and volume variations. These findings suggest that increased blood volume leads to decreased retinal reflectance. Temporal analysis confirmed the ability to capture flicker-induced retinal reflectance changes, indicating its potential for spatial and temporal analysis. Overall, this device offers a portable approach for investigating dynamic retinal responses to light stimuli, which can aid the diagnosis of retinal diseases like diabetic retinopathy, glaucoma, or neurodegenerative diseases affecting retinal blood circulation.
- MeSH
- audiovizuální záznam * přístrojové vybavení MeSH
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- oftalmoskopy * MeSH
- retina * účinky záření fyziologie MeSH
- světelná stimulace * MeSH
- světlo * MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Intradialytic blood pressure (BP) profiles have been associated with all-cause mortality, but its pathophysiology remains unknown. We tested the hypothesis that intradialytic changes in BP reflect excess volume. METHODS: The dry weight reduction in hypertensive haemodialysis patients (DRIP) trial probed dry weight in 100 prevalent haemodialysis patients; 50 patients who did not have their dry weight probed served as time controls. In this post hoc analysis, intradialytic BP was recorded at each of the 30 dialysis treatments during the trial. The slope of intradialytic BP over dialysis was calculated by the log of BP regressed over time. Using a linear mixed model, we compared these slopes between control and ultrafiltration groups at baseline and over time, tested the effect of dry weight reduction on these slopes and finally tested the ability of change in intradialytic slopes to predict change in interdialytic systolic BP. RESULTS: At baseline, intradialytic systolic and diastolic BP dropped at a rate of ~3%/h (P < 0.0001). Over the course of the trial, compared to the control group, the slopes steepened in the ultrafiltration group for systolic but not diastolic BP. Those who lost the most post-dialysis weight from baseline to 4 weeks and baseline to 8 weeks also experienced the greatest steepening of slopes. Each percent per hour steepening of the intradialytic systolic BP slope was associated with 0.71 mmHg [95% confidence interval (CI) 0.01-1.42, P = 0. 048] reduction in interdialytic ambulatory systolic pressure. CONCLUSIONS: Intradialytic BP changes appear to be associated with change in dry weight among haemodialysis patients. Among long-term haemodialysis patients, intradialytic hypertension may, thus, be a sign of volume overload.
- MeSH
- ambulantní monitorování krevního tlaku MeSH
- časové faktory MeSH
- dialýza ledvin MeSH
- hypertenze diagnóza komplikace patofyziologie MeSH
- krevní tlak MeSH
- lidé středního věku MeSH
- lidé MeSH
- nemoci ledvin komplikace patofyziologie terapie MeSH
- prediktivní hodnota testů MeSH
- prospektivní studie MeSH
- randomizované kontrolované studie jako téma MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
Difúzna reflexná spektrofotometria (DRS) patrí medzi neinvazívne vyšetrovacie metódy, ktoré sa v posledných rokoch čoraz častejšie dostávajú do centra záujmu. Nielen rýchly technický rozvoj a nutnosť objektivizácie realizovaných vyšetrení, ale aj zvýšené nároky pacientov kladené na zachovanie celistvosti ľudského tela prispeli k uprednostňovaniu prístrojových neinvazívnych vyšetrovacích metód v diagnostickom procese. Difúzna reflexná spektrofotometria je metóda založená na interakcii optického žiarenia s kožou. Pomocou spektrofotometra sa registruje a analyzuje odrazené (priame aj difúzne) svetlo z jednotlivých častí kože. Tento príspevok je zameraný na technické prevedenie spektrofotometra, zariadenia využívaného pri spektrofotometrii na meranie intenzity svetla v závislosti od vlnovej dĺžky. Podrobne sa analyzovali dostupné konštrukčné typy a jednotlivé súčasti zariadenia. Nami zostrojený spektrofotometer bol skonštruovaný s ohľadom na jednoduchosť konštrukcie a jednoduché nastavenie optických prvkov. Osobitná pozornosť sa venovala zdroju žiarenia, ktorý bol vybratý tak, aby pokryté spektrum bolo čo najširšie a vysielaný signál čo najrovnomernejší a zákazníckemu softvéru na zber dát vyvinutému špeciálne pre túto aplikáciu. Možnosti klinického využitia metódy sú všestranné. Prakticky najvýznamnejšie je jej použitie pri hodnotení erytémov a pigmentácií.
Diffuse reflectance spectrophotometry (DRS) is a non-invasive method recently gaining ground. The rapid technical development and need for objectification of realized examination and preservation of skin surface integrity favours non-invasive methods in the diagnostic process. Diffuse reflectance spectrophotometry is based on the interaction of optic radiation with the skin. Spectrophotemeter registers and analyses the reflected (direct and diffuse) light from the particular skin structures. This report is focused on engineering solution of spectrophotometer, device used in spectrophotometry to measure light intensity in correlation with the wave-length. The available types and components of spectrophotometers were analysed. Our experimental spectrophotometer was developed with regard to construction’s simplicity and easy setup of its technical components. Special attention was paid to selection of light-source and customers’ software for data collection specially designated for this application. This method has a wide clinical use in dermatology especially in evaluation of erythematous skin diseases and pigmentation disorders.
Complex visual signaling through various combinations of colors and patterns has been well documented in a number of diurnal reptiles. However, there are many nocturnal species with highly sensitive vision, being able to discriminate colors in night conditions, as was shown in geckos. Because of their sensitivity to chromatic signals, including UV (ultraviolet), they may have potential hidden features in their coloration, which may play role in intraspecific communication (e.g. mate choice) or interspecific signals (e.g. antipredatory function). We explored this hypothesis in nocturnal Leopard geckos (Eublepharis macularius), a species using visual signals in both antipredation defense and courtship, having ontogenetic color change accompanied by a shift in behavior. We used UV photography and visual modeling in order to compare various aspects of their coloration (luminance, contrast, color proportions) between sexes, age groups and populations. We found that Leopard geckos have considerable UV reflectance in white patches on their tails (and on the head in juveniles). Though, no prominent differences were detected in their coloration between various groups. We hypothesize that the limitation of UV reflectance to the head and tail, which are both actively displayed during defense, especially in juveniles, might potentially boost the effect of antipredation signaling.
- MeSH
- ještěři fyziologie MeSH
- noční vidění fyziologie MeSH
- rozpoznávání obrazu fyziologie MeSH
- sexuální faktory MeSH
- světelná stimulace MeSH
- ultrafialové záření MeSH
- věkové faktory MeSH
- vidění barevné fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The subject of our investigation was the visual features of wing color with special focus on the UV reflectance in the green-veined white butterfly (Pieris napi). Previous studies had concluded that UV reflectance on dorsal wing surfaces is found only in the female P. napi. Based on UV sensitive photography, we analyzed a correlation between 12 geographic and environmental factors and UV reflectance patterns on 3 patches on the forewings of 407 P. napi specimens from the Palaearctic region. Results had shown that females significantly differ from males: they exhibit a 25% higher UV reflectance. To investigate whether and how UV reflectance levels on the forewings and hindwings of both sexes are influenced by the environment, we performed a principal component analysis (PCA) with several environmental variables. For several variables (in particular, latitude and longitude, mean annual temperature and precipitation, and temperature annual range and altitude), the generalized linear model (GLM) model revealed a significant correlation in both sexes. This suggests a link between UV reflectance levels and the environment and distribution of P. napi. We found that stronger UV reflectance is associated with generally more hostile environments and concluded that large-scale environmental factors influence the UV reflectance on the forewings of both male and female green-veined white butterflies.
- MeSH
- motýli * MeSH
- pigmentace * MeSH
- pohlavní dimorfismus MeSH
- ultrafialové záření MeSH
- životní prostředí * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Difúzna reflexná spektrofotometria je neinvazívna vyšetrovacia metóda založená na optických vlastnostiach kože. Použitie metódy v klinickej praxi je široké, najvýznamnejšie je jej využitie pri hodnotení erytémov rôzneho pôvodu, pigmentových lézií, porúch pigmentácie a pri vyhodnocovaní kožných fototypov a kožných testov. Na našej klinike sme pomocou tejto metódy hodnotili absorpčné vlastnosti normálnej kože a kože s klinickými prejavmi vitiliga v experimentálnej skupine vybraných pacientov vo veku od 3 do 18 rokov života a vývoj cievnych malformácii u detí od novorodeneckého veku do 3 rokov života. Experimentálnym difúznym reflexným spektrofotometrom sme merali nepostihnutú oblasť kože v axile u detských pacientov s fototypom II, III, V a VI. U každého pacienta sa hodnotili spektrálne krivky a z nich obsah a absorpčná charakteristika oxyhemoglobínu, deoxyhemoglobínu a melanínu. Druhou vyšetrovanou skupinou boli pacienti s poruchami pigmentácie, najmä s prejavmi vitiliga. Následne sme sa zamerali na dermatologické choroby s klinickými prejavmi erytému, kde sme hodnotili pomocou spektrálnej absorpčnej krivky intenzitu erytematóznej zložky zápalovej reakcie a monitorovali vývoj cievnych malformácií, predovšetkým hemangiómov. Difúzna reflexná spektrofotometria umožňuje zaraďovať pacientov medzi jednotlivé fototypy, umožňuje monitorovať morfologické zmeny hemangiómu s rastom dieťaťa, určuje množstvo chromofórov, hlavne oxyhemoglobínu v erytematóznych léziách, melanínu v normálnej koži a jeho nedostatok v hypopigmentovaných a depigmentovaných oblastiach kože a v neposlednom rade poskytuje informácie o cievnom prekrvení vyšetrovanej lézie. Podľa našich dát získaných opakovanou neinvazívnou spektrálnou analýzou v oblasti viditeľného svetla je možné predpokladať budúci vývoj hemangiómov v detskom veku a správne manažovať fototerapiu pacientov s vitiligom.
Diffuse reflectance spectrophotometry is a non-invasive method to investigate optical properties of the skin. This method has a wide clinical use in dermatology, especially, in evaluation of erythematous skin diseases, pigmented skin lesions, disorders of pigmentation and skin tests. We used this method to evaluate normal skin and skin with clinical features of vitiligo within a group of children in age from 3 to 18 years and haemangiomas within a group of neonates to 3. year-old infants. We measured reflected visible light from different areas of normal skin, depigmented skin and haemangioma and made a spectral analysis of data acquired. Examinations with special probes are perfomed very quickly, in a non-invasive manner, and it is possible to repeat them more times without any discomfort or any negative impact on infants. This method helps to range patients into different phototype groups, gives unique opportunity to monitor morphological haemangiomas changes during growth of the infant, estimates amount of chromophores, mainly oxyhaemoglobine in erythematous lesions, melanin in normal skin, lack of this chromophore in hypopigmented and depigmented skin and determines blood perfusion in examined lesions. According to our data obtained by repeated non-invasive spectral analysis in visible light we can predict the future development of haemangiomas in childhood and manage phototherapy of vitiliginous skin.
Plant survival in temperate zones requires efficient cold acclimation, which is strongly affected by light and temperature signal crosstalk, which converge in modulation of hormonal responses. Cold under low light conditions affected Arabidopsis responses predominantly in apices, possibly because energy supplies were too limited for requirements of these meristematic tissues, despite a relatively high steady-state quantum yield. Comparing cold responses at optimal light intensity and low light, we found activation of similar defence mechanisms-apart from CBF1-3 and CRF3-4 pathways, also transient stimulation of cytokinin type-A response regulators, accompanied by fast transient increase of trans-zeatin in roots. Upregulated expression of components of strigolactone (and karrikin) signalling pathway indicated involvement of these phytohormones in cold responses. Impaired response of phyA, phyB, cry1 and cry2 mutants reflected participation of these photoreceptors in acquiring freezing tolerance (especially cryptochrome CRY1 at optimal light intensity and phytochrome PHYA at low light). Efficient cold acclimation at optimal light was associated with upregulation of trans-zeatin in leaves and roots, while at low light, cytokinin (except cis-zeatin) content remained diminished. Cold stresses induced elevation of jasmonic acid and salicylic acid (in roots). Low light at optimal conditions resulted in strong suppression of cytokinins, jasmonic and salicylic acid.
A comparison of 95 species of Central European moths, representing 11 families and inhabiting various habitats, was carried out in order to detect the potential impact of biotope on the ultraviolet (UV) light reflectance of their wings. Based on digitized photographs taken under UV light conditions, a phylogeny-controlled redundancy analysis relating UV reflectance to preferred habitat type (xerophilous, mesophilous, and hygrophilous) and habitat openness (open, semiopen, and closed) was carried out. Species preferring hygrophilous habitats displayed significantly higher UV wing reflectance than species inhabiting xerothermic and mesic habitats, and this pattern remained significant even after controlling for phyletic relationships. In contrast, UV wing reflectance displayed no pattern related to habitat openness. Given the higher UV reflectance of water and humid surfaces, we interpret these results, which are based on the first comprehensive sampling of UV reflectance in Central European moths, in terms of predator avoidance under habitat-specific light conditions. We conclude that the moisture content of the environment may markedly contribute to the variation of appearance of moth wings for better imitation habitat characteristics and therefore to increase protection.
- MeSH
- ekosystém * MeSH
- křídla zvířecí fyziologie MeSH
- můry fyziologie MeSH
- pigmentace MeSH
- ultrafialové záření * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Autoři se ve svém sdělení zabývají technikou přímého lepení ortodontických zámků pomocí světlem tuhnoucích kompozitních adheziv. Krátce se zamýšlejí se nad hlavními výhodami a nevýhodami této techniky a jejím přínosem k terapii fixními aparáty. Pracovní postup je ilustrován na příkladě kompozitního adheziva Leoně F3170-01.
The authors discuss the technique of direct orthodontic bracket bonding with visible-light polymerized adhesives. They reflect briefly on the main advantage and disadvantage of this technique and its contribution to orthodontic therapy. Technical procedure is illustrated with composite adhesive Leone F 3170-01.
- MeSH
- dentinová adheziva MeSH
- kompomery MeSH
- lidé MeSH
- metoda terčíkového zámku MeSH
- ortodoncie metody MeSH
- světlo MeSH
- Check Tag
- lidé MeSH
A dedicated field experiment was conducted to investigate the response of a green reflectance continuum removal-based optical index, called area under the curve normalized to maximal band depth between 511 nm and 557 nm (ANMB511-557), to light-induced transformations in xanthophyll cycle pigments of Norway spruce [Picea abies (L.) Karst] needles. The performance of ANMB511-557 was compared with the photochemical reflectance index (PRI) computed from the same leaf reflectance measurements. Needles of four crown whorls (fifth, eighth, 10th, and 15th counted from the top) were sampled from a 27-year-old spruce tree throughout a cloudy and a sunny day. Needle optical properties were measured together with the composition of the photosynthetic pigments to investigate their influence on both optical indices. Analyses of pigments showed that the needles of the examined whorls varied significantly in chlorophyll content and also in related pigment characteristics, such as the chlorophyll/carotenoid ratio. The investigation of the ANMB511-557 diurnal behaviour revealed that the index is able to follow the dynamic changes in the xanthophyll cycle independently of the actual content of foliar pigments. Nevertheless, ANMB511-557 lost the ability to predict the xanthophyll cycle behaviour during noon on the sunny day, when the needles were exposed to irradiance exceeding 1000 µmol m(-2) s(-1). Despite this, ANMB511-557 rendered a better performance for tracking xanthophyll cycle reactions than PRI. Although declining PRI values generally responded to excessive solar irradiance, they were not able to predict the actual de-epoxidation state in the needles examined.
