In many plant species that remain leafless part of the year, CO2 fixation occurring in green stems represents an important carbon gain. Traditionally, a distinction has been made between stem photosynthesis and corticular photosynthesis. All stem photosynthesis is, sensu stricto, cortical, since it is carried out largely by the stem cortex. We proposed the following nomenclature: stem net photosynthesis (SNP), which includes net CO2 fixation by stems with stomata in the epidermis and net corticular CO2 fixation in suberized stems, and stem recycling photosynthesis (SRP), which defines CO2 ling in suberized stems. The proposed terms should reflect differences in anatomical and physiological traits. SNP takes place in the chlorenchyma below the epidermis with stomata, where the net CO2 uptake occurs, and it resembles leaf photosynthesis in many characteristics. SRP is found in species where the chlorenchyma is beneath a
well-developed stomata-free periderm and where reassimilation of internally respired CO2 occurs. SNP is common in plants from desert ecosystems, rates reaching up to 60% of the leaf photosynthetic rate. SRP has been demonstrated in trees from temperate forests and it offsets partially a carbon loss by respiration of stem nonphotosynthetic tissues. Reassimilation can vary between 7 and 123% of respired CO2, the latter figure implying net CO2 uptake from the atmosphere. Both types of stem photosynthesis contribute positively to the carbon economy of the species, in which they occur; they are advantageous to the plant because they allow the maintenance of physiological activity during stress, an increase of integrated water use efficiency, and they provide the carbon source used in the production of new organs., E. Ávila, A. Herrera, W. Tezara., and Obsahuje bibliografii
The paper presents selected results of seismological observations in Silesia and northern Moravia between 01/2004 - 08/2008, which are based on interpretation of three-component digital recordings at solitary seismic stations operated by the Institute of Geonics of the ASCR Ostrava (IGN) distributed in the region under investigation. Five seismic stations had recorded local tectonic seismic events in a continuous regime until 12/2005, when the grant project GA CR No. 205/03/0999 terminated. Meanwhile, the Ostrava - Krásné Pole (OKC) seismic station have continued in operation as a part of the Czech regional seismological network since 1983 up to present. Other three stations have been operating in a so-called triggered regime. At the mid-January 2007, seismic station in Klokočov village was re-opened in continuous regime. During 55 months of observation, 90 tectonic events have been detected at one or more seismic stations mentioned above. However, database of the Institute of Physics of the Earth of the MU contains more than 640 microearthquakes during the same time. This discrepancy is caused mainly due to a higher concentration of microearthquake foci distributed all over the western part of the region under investigation where the IPE seismic stations are situated. On the other hand, the IGN seismic stations are spread predominantly within the eastern part of the territory, i.e. relatively far from the recent foci, and moreover, some stations are operated using the triggered regime., Karel Holub, Zdeněk Kaláb, Jaromír Knejzlík and Jana Rušajová., and Obsahuje bibliografii
The contribution of two components (ΔpH and ΔE) of the proton motive force to photosynthesis of C. reinhardtii was studied. Valinomycin, a photophosphorylation uncoupler, decreased significantly the fast phase (related mainly to the membrane electric potential) of millisecond delayed light emission (ms-DLE) of C. reinhardtii. Nigericin, another photophosphorylation uncoupler, decreased the slow phase (related mainly to the proton gradient) and partly also the fast phase of ms-DLE. Both valinomycin and nigericin decreased the net ATP content and photosynthetic rate of C. reinhardtii, but the inhibition by nigericin was stronger than that by valinomycin. Hence both components of the proton motive force contribute to photosynthesis and although the contribution of ΔpH is larger than that of ΔE, the latter is not negligible in photosynthesis of C. reinhardtii. and Qing-Xiu Tang, Jia-Mian Wei.
This paper deals with the phenomenon of the parametric anti-resonance of autoparametric systems. It is shown that parametric anti-resonance (additional parametric excitation fulfilling special conditions) can be used not only to suppress self-excited or externally excited vibrations but can also be used to stabilize the equilibrium position ot the autoparametric system. and Obsahuje seznam literatury
Experimental geomechanical and seismological measurements are performed in the medieval Jeroným Mine near Čistá (Sokolov district). The main aim of this activity is geomech anical stability evaluation of this monument. Periodical monitoring was started in 2001 whereas quarterly period was applied (measurement of crack development in the mine working, development in changes in convergence cross-sections of linear and spatial workings and fluctuations of water levels in underground spaces). Seismological monitoring was started during reconstruction of partly impassable drainage adit. At present, selected parts of described geomechanical system are newly instrumented to obtain continuous information. Data obtained from periodical and continuous monitoring are presented in this contribution. Interpretation of seismological data on both natural and technical seismicity and fluctuations of water levels is presented in details., Zdeněk Kaláb, Jaromír Knejzlík, Robert Kořínek, Radovan Kukutsch, Markéta Lednická and Petr Žůrek., and Obsahuje bibliografické odkazy
A morphologically distinct intrusive massif emerges from sedimentary Mesozoic/Tertiary cover in Eastern Socotra forming the high Haggier Mts. It is mostly composed of peralkaline a nd hypersolvus granite partly accompanied by gabbroic rocks. Amphibole, the sole mafic mineral of th e granite, shows predominately the arfvedsonite composition, while riebeckite, for which Socotra is reported in most manuals of mineralogy as the "locus typicus", occurs subordinately only. Either Paleozoic or Tertiary age has been assumed for this massif for a long time. In the last decade, however, K/Ar datings have been published clearly showing Precambrian (Ne oproterozoic) age. The present authors confirm with somewhat modified results this statement by five new radiometric measurements of monomineral amphibole fractions yiel ding values of 687 to 741 Ma for granites and 762 Ma for gabbroic rocks. The massif represents an isolated segment of numerous late postorogenic Pan-African A-granite bodies piercing the Nubian-Arabian Shield an d is explained as the result of partial melting of Pan-African calc-alkaline shield rocks in the closing stage of the orogeny., Ferry Fediuk and Kadosa Balogh., and Obsahuje bibliografické odkazy
The aim of this paper is the determination of six orbital elements if two positions (1 and 2) of a solar system body are known. The task was solved using the ratio of the elliptical sector to the area of the corresponding triangle. This relationship was labelled as η and derived by K. F. Gauss (1809), see sections 1 and 2. This paper presents four easy methods that supply the ratio, see section 3. These methods simplify this task by removing long and very complicated derivations and by clarifying the theory and calculations. The methods are not used in the case of more than two observations., Josef Kabeláč., and Obsahuje bibliografii
The present study proposed procedure for predicting an optimal left and right ventricular pacing interval delay (V-V interval). In 16 patients (heart failure, left bundle branch block, biventricular pacing) two methods (A and B) identifying optimal V-V interval were tested. Method A: predicted optimal V-V interval A (POVV-A) = electromechanical delay of the segment paced by left ventricle lead minus electromechanical delay of the segment paced by right ventricle lead. Method B: predicted optimal V-V interval B (POVV-B) = difference in the onset of aortic and pulmonary flows. Both methods were validated using echocardiography and right-sided heart catheterization. Cardiac output during POVV-A (4.6 l.min-1 ) was significantly better than that during POVV-A minus 20 ms (4.3 l.min-1, p<0.01) and POVV-A plus 20 ms (4.3 l.min-1 , p<0.01), and than that during POVV-B (4.4 l.min-1, p<0.05). LV dP/dt during POVV-A (818 mm Hg.s-1 ) exceeded that during POVV-A plus 20 ms (717 mm Hg.s-1 , p<0.05) and POVV-A minus 20 ms (681 mm Hg.s-1, p<0.05), and that during POVV-B (727 mm Hg.s-1 , p<0.01). The time difference in onsets of myocardial deformation of left ventricle segment paced by the left ventricle and right ventricle lead allows identifying the optimal V-V interval and improves left ventricle performance., M. Novák, J. Lipoldová, J. Meluzín, J. Krejčí, P. Hude, V. Feitová, L. Dušek, P. Kamarýt, J. Vítovec., and Obsahuje bibliografii a bibliografické odkazy