The epiphytic fern Platycerium bifurcatum grows in different habitats characterized by drought and high irradiance stress. The plant shows diurnal malate oscillations, indicative for CAM expression only in cover leaves, but not in sporotrophophyll. In P. bifurcatum cover leaves exposed to high irradiance and desiccation, the decrease in both CO2 assimilation (PN) and stomatal conductance (gs) was accompanied with occurrence of diurnal malate oscillations. Exogenously applied abscisic acid (ABA) induced the decrease in PN and gs, but no clear change in malate oscillations. The measurements of the maximum quantum efficiency of photosystem 2 (Fv/Fm) under high irradiance showed distinct photoinhibition, but no clear changes in Fv/Fm due to desiccation and ABA-treatment were found. and G. Rut ... [et al.].
The aim of this study was to evaluate myofibrillar creatine kinase (EC 2.7.3.2) activity on the background of the effect of substrate channeling by myosin ATPase and to compare it with creatine kinase (CK) activity of whole skinned fibers. In order to assess CK activity, skinned fibers were prepared from the rat psoas major muscles defined by light microscopy. The activity in permeabilized fibers after treatment with saponin, Triton X-100 and Ca2+-free medium reached 2.80, 6.97 and 3.32 m mol ATP min-1 mg-1 protein, respectively, when a coupled enzyme assay system with external hexokinase and glucose-6-phosphate dehydrogenase was used. Transmission electron microscopy (TEM) revealed a possible interference among activities of sarcolemmal, sarcoplasmic, myofibrillar and mitochondrial CK from persisting structures. For evaluation of the myofibrillar CK itself, a pure myofibrillar fraction was prepared. Fraction purity was confirmed by TEM and by enzymatic assays for marker enzymes. Two procedures, i.e. the coupled enzyme assay and the evaluation of phosphocreatine (Pcr) concentration before and after the CK reaction, were used for measurement of CK activity in this fraction. The procedures resulted in 3.2 nmol ATP min-1 mg-1 protein and 7.6 nmol PCr min-1 mg-1 protein, respectively. These alternative approaches revealed a discrepancy between the reacting portions of Pcr by more than 50 % , which provides information about the size of the effect, generally described as substrate channeling., M. Gregor, J. Mejsnar, A. Janovská, J. Žurmanová, O. Benada, B. Mejsnarová., and Obsahuje bibliografii
Th e paper aims at identifying, explaining and illustrating the aff ordances of “creative nonfi ction” as a style of writing social science. Th e fi rst part introduces creative nonfi ction as a method of writing which brings together empirical material and fi ction. In the second part, based on illustrations from my ethnographic research of European “crisis reporters,” written in the form of a novel about a fi ctional journalist, but also based on a review of existing social science research that employs a creative method of writing, I identify several main aff ordances of creative nonfi ction in socialscientifi c research. In particular, I argue that creative nonfi ction allows scientists to illustrate their fi ndings, to express them in an allegorical way, to organize data into a narrative, to let their pieces of research act in the social world, and to permeate research accounts with self-refl exive moments. I also discuss some apparent negative aff ordances: challenges that creative nonfi ction poses to readers and to the institutionalized academic discourse. Finally, I suggest that writing about sociological problems in the style of creative nonfi ction can help to produce more engaging and engaged texts, and I discuss the ethical implications of the approach. and Článek identifi kuje, vysvětluje a ilustruje afordance „kreativní nonfi kce“ jako stylu psaní o sociální vědě. V první části představuji kreativní nonfi kci jako metodu psaní, která kombinuje empirický materiál a imaginaci. Ve druhé části na základě ukázek z vlastního etnografi ckého výzkumu evropských “krizových reportérů”, psaného formou románu o fi ktivním novináři, a také na základě jiných sociálněvědných výzkumů, které používají kreativní metody psaní, identifi kuji několik hlavních afordancí kreativní nonfi kce v sociálněvědním výzkumu. Kreativní nonfi kce zejména umožňuje vědkyním a vědcům jinak a někdy lépe ilustrovat jejich zjištění, vyjádřit tato zjištění alegoricky, organizovat data a vytvářet narativ, podpořit efektivitu výzkumů v sociálním světě nebo také proložit výzkumný narativ seberefl exivními prvky. Text ale diskutuje i zjevné negativní afordance, tedy výzvy, které potenciálně plynou ze setkání kreativní nonfi kce se čtenářstvem a s institucionalizovaným akademickým diskurzem. Nakonec diskutuji některé etické implikace představeného přístupu a tvrdím, že psát o sociologických problémech ve stylu kreativní nonfi kce může pomoct vytvářet texty, které budou angažované i poutavé.
This study describes Crenosoma brasiliense (Nematoda, Metastrongyloidea), a new species parasitic in bronchi and bronchioles of Galictis cuja (Molina) (Carnivora, Mustelidae) from Brazil. This species differs from other 11 species of Crenosoma by having a cuticular projection at the distal end of the spicules, forming a prominent blade at the tip of the spicule, a vulval cuticular appendage with a triangular shape and prominent vulval lips. There are no previous records of species of Metastrongyloidea in G. cuja or species of Crenosoma in South America. Therefore, the new species represents the first host record and first geographical record of species of Crenosoma in South America.
Článek přibližuje botanickou exkurzi do Brazílie na horu Corcovado (710 m n. m.), nacházející se u pobřeží Atlantského oceánu, na vrcholu se sochou Krista Vykupitele (Cristo Redentor). Území leží v národním parku Tijuca, který byl zřízen na ochranu tropického deštného lesa, zde nazývaného mata atlântica (atlantský les). Autor představuje některé významné skupiny zdejší flóry, vybrané endemické taxony či rostliny se zajímavou životní strategií., This article presents a botanical excursion up Mount Corcovado (710 m a. s. l.) on the Atlantic coast of Brazil, with the statue of Christ the Redeemer (Cristo Redentor) at the top. The territory belongs to the Tijuca National Park, established to protect the tropical rain forest - called mata atlântica (Atlantic forest). Several important groups of local flora, selected endemic taxons and also plants with interesting life strategies are presented here., and Miloslav Studnička.
Calibrating and verifying 2-D and 3-D vadose zone flow and transport models requires detailed information on water and solute redistribution. Among the different water flow and mass transfer determination methods, staining tracers have the best spatial resolution allowing visualization and quantification of fluid flow including preferential flow paths. Staining techniques have been used successfully for several decades; however, the hydrological community is still searching for an “ideal” vadose zone tracer regarding flow path visualization. To date, most research using staining dyes is carried out with Brilliant Blue FCF. Fluorescent dyes such as Uranine, however, have significant advantages over nonfluorescents which makes them a promising alternative. This paper presents the first analysis of key properties any fluorescent substance must possess to qualify as a staining fluorescent tracer in vadose zone hydrological applications. First, we summarize the main physico-chemical properties of Uranine and evaluate its staining tracer potential with conventional suitability indicators and visibility testing in a soil profile. Based on numerical analysis using the theory of fluorescence, we show that a low molar absorption coefficient is a crucial parameter to quantify concentration accurately. In addition, excitation of a tracer on wavelengths different from the maximum excitation wavelength can extend the linear range of the concentration-fluorescence relationship significantly. Finally, we develop criteria for evaluating the suitability of any potential fluorescent soil staining compound for soil hydrological applications: 1) high quantum yield, 2) low molar absorption coefficient, 3) fluorescence independent of temperature, 4) low photodecomposition rates, and 5) fluorescence stable across a wide range of pH values.
Elastic critical buckling stress of the plate girder subjected to transverse force is calculated. The load is applied through the flange and resisted by shear forces in the web. Comparisons of values of buckling coefficient kσ,b = f (α, β) (Tab.2) obtained by 5 various authors: Petersen, von Berg, Ravinger, Kutzelnigg, Protte (Tab. 1) and calculated by computer program PLII (Tab. 2). Simply supported rectangular plate (a - length, b - width, t - thickness) without flanges and stiffeners is investigated for different aspect ratios α = a/b = 1; 2; 3; 4; 5; 8; 10; 20; 30; 40 when subjected to transverse uniformly distributed partial load having relative load lengths β = c/a = 0.005 (single concentrated force); 0.2; 0.4; 0.6; 0.7; 0.8; 1 (uniformly distributed load along a). The values of buckling coeffficient kσ,b = f (α, β, δ) calculated by program PLII (Tab. 3). Parametrical study of simply suppported rectangular plate without stiffeners with α = a/b = 4; 5; 8; 10; 20; 30; 40, β = c/a = 0.005 (single concentrated force); 0.01; 0.05; 0.1; 0.2; 0.3; 0.4 and different relative normal flange rigidity δ = Af / (b t) = 0 (without flange); 0.3; 0.5; 1; 1.5; 2; 3. Torsional rigidity of the flanges is not taken into account. and Obsahuje seznam literatury
A single fracture-mechanics based method is described for assessing a part-through crack in the wall of a pipe subjected to internal pressure of liquid and/or gas. The method utilizes simple approximate expressions for determining the fracture parameters K, J, and employs these parameters to determine critical dimensions of crack on the basis of equality between the J-integral and the J-based fracture toughness of the pipe steel. The crack tip constraint is accounted by the so-called plastic constraint factor C, by which the uniaxial yield stress in the J. integral equation is multiplied. The results of the prediction of the fracture condition are verified by burst tests on test pipes. and Obsahuje seznam literatury
Goldspur apple (Malus pumila cv. Goldspur) is one of the main fruit trees planted in semiarid loess hilly areas. The photosynthetic efficiency in leaves of eight-year-old trees were studied under different soil water conditions with a Li-6400 portable photosynthesis system and a Li-Cor1600 portable steady state porometer in order to explore the effects of soil water stress on photosynthesis and the suitable soil water content (SWC) for water-saving irrigation of apple orchards. The results showed that the leaf net photosynthetic rate (P N), transpiration rate (E), water-use efficiency (WUE), stomatal conductance (gs), intercellular CO2 concentration (Ci), and stomatal limiting value (Ls) displayed different threshold responses to soil water variation. When SWC was within a range of about 60%-86% of field capacity (FC), PN and E were maintained in a relative steady state. At an elevated level but below 60% of FC, both PN and E decreased evidently with decreasing soil moisture. The SWC needed to support WUE in a relatively steady state and at a high level was in the range of about 50%-71% of FC. When SWC was less than 48% of FC, g s and Ls declined with decreasing soil moisture, while Ci increased rapidly. Based on the analysis of the stomatal limitation of photosynthesis using two criteria (Ci and Ls) suggested by Farquhar and Sharkey, it was implied that the predominant cause of restricting PN had changed from stomatal limitation to nonstomatal one under severe water stress. In terms of water-saving irrigation for enhancing water-use efficiency, it was concluded that in semiarid loess hilly areas, the suitable range of SWC for water-saving irrigation in goldspur apple orchards is in the range of about 50%-71% of FC, and the most severe degree of soil water stress tolerated for photosynthesis is about 48% of FC. and S. Y. Zhang ... [et al.].