Nowadays, increasing attention is being paid to the biological significance of UV- -reflecting patterns exposed on the outer surfaces of various organisms. UV radiation plays an important role in the communication of many species of organisms. Here we give a brief overview of the biological functions of UV reflectance in some groups of invertebrates. Special attention is paid to the role of UV reflectance in sexual selection, foraging strategies, and the evolution and ecology of a species in general. and Pavel Pecháček, David Stella, Karel Kleisner.
Mnoho skupin živočichů disponuje zrakem citlivým na tzv. ultrafialové světlo. Jednou z takových skupin jsou i různí opylovači, kteří nám dobře známé květy mohou vidět v trochu odlišných barvách, než my. Na květech rostlin totiž často existují vzory patrné pouze v ultrafialové části spektra, které jsou pro člověka neviditelné. V první části seriálu o výskytu a významu těchto vzorů u rostlin se zabývá historií odhalování citlivosti živočichů na ultrafialové světlo, přibližuje otázky, jak funguje zrak a jakým způsobem ultrafialové zbarvení na povrchu organismů vzniká., The vision of many animal groups is sensitive to the so-called ultraviolet (UV) light. These groups include various pollinators, which may see flowers that are quite familiar to us in a different coloration. That is because flowers often feature patterns visible only in the UV part of the spectrum, and thus invisible to humans. This series deals with the occurrence of such patterns and their significance for plants. The first part recounts the history of discovering the sensibility of animals to UV light, expounds on the way how vision works, explains the origin of UV coloration on organismal surfaces., and Pavel Pecháček.
Význam ultrafialových znaků v životě různých organismů byl dlouho opomíjen především z toho důvodu, že UV paprsky jsou pro lidský zrak za normálních okolností neviditelné. Jedna z možností, jak si můžeme ultrafialovou podobu živočichů či rostlin zviditelnit, je použití speciálně upraveného klasického či digitálního fotoaparátu. Druhý díl seriálu o ultrafialových vzorech na květech rostlin se zabývá vývojem techniky záznamu UV podoby různých organismů a popisem získávání fotografií, které doprovázejí tento text. Druhá část článku je věnována vybraným druhům našich nejběžnějších rostlin a charakterizaci jejich ultrafialových znaků., The significance of UV characteristics for the life of various organisms has been neglected for a long time. It stems mainly from the fact, that under normal circumstances, UV rays are invisible to the human eye. One of the ways to make the UV appearance of animals or plants visible is to use a specially adjusted classic or digital camera. This second paper deals with the UV patterns on flowers. It focuses on the development of techniques which allow us to capture the UV appearance of various organisms, and provides a methodology with which the accompanying photos were taken. The article also presents selected species of common native plants, with a description of their UV characteristics., and Pavel Pecháček.
The last part of this series about UV characters on plant flowers presents UV images of several other common plant species native to the Czech flora. Attention is also paid to the possibility of using herbarium material for research into the UV characters of plants. The article summarizes recently discovered knowledge along with the evolutionary and ecological factors behind the emergence and significance of UV characters on plant flowers, particularly their role in the communication of pollinators. and Pavel Pecháček.
Ultrakrátké světelné pulzy, tedy pulzy pikosekundové nebo kratší časové délky, jsou velmi významné ve vědě i ve stále větším počtu aplikací. Uvádíme základní vlastnosti světelných pulzů, způsob jejich generace lasery se synchronizací módů a připomínáme některé oblasti jejich použití., Ultra-short light pulses, with pulses of a picosecond or shorter duration, are very important in science as well as in a growing number of applications. We review the basic properties of these light pulses and techniques for their generation by modelocked lasers. We also describe some of their application areas., Petr Malý., and Obsahuje seznam literatury
The diversity of colours is one of the most typical features of vernacular architecture. The submitted study deals with the research on the use of ultramarine on the Pannonian type of folk house, which could be found in central, southern, and south-eastern Moravia. The authors primarily proceed from the younger shift of the house. This featured, among other things, mainly the original transformation of stylistic elements, the façade segmentation, and the diversity of colours used on the frontages of residential buildings. Blue pigments were only barely available by the early nineteenth century, especially in the rural environment. The use of blue pigments flourished in vernacular architecture only after 1828, when the technique for the production of ultramarine was published. This was followed by industrial production of this pigment. The technique for the production of ultramarine, applied in the past, is described e. g. in the publication Tovární výroba barev [Factory Production of Dyes] by Jaroslav Milbauer from 1926. The treatise interconnects the cultural-historical and the technical level of the phenomenon under study. The material-analytical section is based on ethnological field research and an analysis of historical plasters using both physical-chemical methods of their identification and the knowledge of material engineering. Ethnological knowledge thus acquires a completely new dimension, and it is supplemented by new conclusions. At the same time, it is also a detailed analysis of the structure of ultramarine currently acquired on our market and an attempt at its laboratory synthesis. The result of the presented experiment with the production of blue pigment can be beneficial in practice for restoration purposes and professional analysis of historical plasters.
The remarkable progress in laser technology leads also to a development of techniques of time-resolved optical spectroscopy. The ultrafast laser spectroscopy in the visible spectral region can be now used for investigation of rapid processes with the time resolution of about 10 fs. This paper reviews the experimental background and typical techniques of ultrafast laser spectroscopy. The potentional of ultrafast spectrocopy is illustrated with the results obtained by authors in the field of ultrafast relaxation processes in semiconductors and semiconductor nanostructures., Petr Malý, Petr Němec, František Trojánek., and Obsahuje bibliografii
Ultraslabá emise fotonů se vyskytuje prakticky u všech metabolicky aktivních biologických systémů. Jejím zdrojem jsou elektronově excitované stavy molekul vznikající v průběhu oxidativních reakcí biomolekul. Ultraslabá emise fotonů detekovatelná citlivými a nízkošumovými fotonásobiči a CCD kamerami může najít uplatnění v neinvazivních diagnostických metodách v zemědělství a biomedicíně., Ultra-weak photon emission is present in virtually all metabolically active biological systems. Its source is electronically excited states of molecules produced during the oxidation reactions of biomolecules. Ultra-weak photon emission detected with sensititive and low noise photomultipliers and CCD cameras can be exploited in non-invasive diagnostics in biomedicine and agriculture., Michal Cifra, Pavel Pospíšil., and Obsahuje seznam literatury
Genetic predisposition and social stress may represent important risk factors in etiology of hypertension associated with endothelial dysfunction. Perturbations of endothelial structural integrity are also critical for the pathogenesis of vascular diseases. We examined effect of chronic social stress on structure of aortic endothelium in bord erline hypertensive (BHR) and normotensive Wistar rats. Male BHR – offspring of Wistar mothers and SHR fathers and age-matched W were exposed to 6-week crowding stress (5 rats/cage, 200 cm2/rat). Aortic tissue was processed for electron microscopy and NO synthase activity measurement. Crowding stress significantly increased blood pressure in BHR compared to basal values (140±3 mm Hg vs. 130±3 mm Hg, p<0.05) and reduced enzyme activity by 37 % (p<0.01) in the aorta of BHR. Local slight structural alterations of endothelium were found in non-stressed BHR (p<0.001) when compared with Wistar rats. Chronic stress caused marked (p<0.005) subcellular injury of endothelial cells in aorta of BHR characterized by mitochondrial damage, presence of vacuoles, increased number of lysosomes, Weibel-Palade bodies, changes of intercellular connections and local disruption of endothelium, while only slight changes were seen in Wistar rats. Results suggest increased sensitivity of aortic endothelium of BHR to chronic crowding that may contribute to acceleration of arterial dysfunction., Ľ. Okruhlicová, K. Dlugošová, M. Mitašíková, I. Bernátová., and Obsahuje bibliografii a bibliografické odkazy
This paper describes the fine structure of oocysts of Nematopsis sp. (Apicomplexa, Porosporidae) found in the abductor muscles of seawater clams, Meretrix meretrix (Linnaeus, 1758) (Veneridae), collected near the city of Dammam (6°17'0''N, 50°12'0''E) in the Arabian Gulf off the coast of Saudi Arabia. Oocysts of an ellipsoidal shape were found among myofibrils of the abductor muscles of infected clams. Each oocyst is composed of an oocyst wall surrounding a single uninucleate vermiform sporozoite located in the lumen of the oocyst wall. The thin oocyst wall (0.70-0.85 µm thick) is composed of homogenous electron-lucent material formed by three layers of equal-thickness. The oocyst wall contains a plano-convex opercular-like structure about 2.5 µm in diameter and 0.75-0.90 µm thick, composed of a homogenous material with moderate electron density. The oocyst is of an ellipsoidal shape and is 15.6 ± 0.6 µm long and 11.1 ± 0.7 µm wide. Externally, the oocyst wall is surrounded by a complex dense network of numerous anastomosed microfibrils, which are attached to the oocyst wall, forming 2-3 layers and extending towards the periphery, at some points penetrating amongst the host cells. The myofibrils in some cases show evident aspects of lysis as a consequence of the appearance of lysosome-like vesicles. Lacking knowledge of a complete life cycle and/or molecular data precluded the conclusive identification of this species.