The rate of photosynthesis (PN) in leaves and pods as well as carbon isotope content in leaves, pod walls, and seeds was measured in well-watered (WW) and water-stressed (WS) chickpea plants. The PN, on an area basis, was negligible in pods compared to leaves and was reduced by water stress (by 26%) only in leaves. WS pod walls and seeds discriminated less against 13CO2 than did the controls. This response was not observed for leaves as is usually the case. Pod walls and seeds discriminated less against 13CO2 than did leaves in both WW and WS plants. Measurement of carbon isotope composition in pods may be a more sensitive tool for assessing the impact of water stress on long-term assimilation than is the instantaneous measurement of gas exchange rates. and M. H. Behboudian ... [et al.].
a1_Perennial organ functions of trees living in seasonal environments exhibit temporal changes that can be classified as long-term interannual changes and seasonal fluctuations within single years. However, few studies have separately quantified these changes from longitudinal measurement data or analyzed the relationships between them. We developed a hierarchical Bayesian statistical model consisting of three parts: a long-term interannual change expressed by consecutive annual linear trends, seasonal fluctuations with 26 values for two-week periods in a year, and a random effect for repeated measurements. The model can extract long-term interannual changes and seasonal fluctuations from longitudinal repeated measure data. The pattern of seasonal fluctuation, the amount of seasonal fluctuation, and the net annual change are expressed by the estimated model parameters. We applied our model to foliar chlorophyll (Chl) and nitrogen (N) content measured repeatedly on more than 1-year-old leaves of saplings in four evergreen broad-leaved tree species using nondestructive optical methods. The model successfully explained large variations in the Chl and N content. In general, seasonal fluctuations corresponded to the phenology of current-year leaves; Chl and N tended to decrease from the opening to maturation of new leaves and increased during the rest period. The magnitude of the decrease in the Chl and N content in the growth period of current-year leaves (Δγ) did not decrease noticeably as leaves aged. For the Chl content, Δγ was positively correlated with the maximum value before leaf opening across species. For the N content, Δγ and the maximum value before leaf opening were not clearly correlated across species, but were positively correlated within some species., a2_A model parameter for annual linear trends in Chl and N varied from positive (indicating increasing trends) to negative values (indicating decrease) depending on species and leaf age in years., D. Mizusaki, K. Umeki, T. Honjo., and Obsahuje seznam literatury
Článek se zabývá disertací Nielse Bohra, kterou obhájil roku 1911. V první části je nastíněn vývoj Bohrovy disertační práce a jeho snahy práci přeložit do angličtiny. Dále Bohrův pobyt v Cambridgi u J. J. Thomsona a důvody, proč se nakonec rozhodl strávit zbytek svého zahraničního studijního pobytu v Manchesteru u E. Rutherforda. Druhá část příspěvku shrnuje historii vývoje elektronové teorie kovů. Nakonec jsou uvedeny závěry, ke kterým Bohr došel a ze kterých můžeme vyzdvihnout ten, že klasická mechanika je pro objekty na atomární úrovni nedostatečná., The article deals with Niels Bohr‘s dissertation defended in 1911. The first part of the article outlines the development of Bohr‘s dissertation and his strong efforts to translate the work into English. It also depicts Bohr‘s stay in Cambridge with J. J. Thomson and the reasons why he decided to spend the rest of his study abroad in Manchester with E. Rutherford. The second part describes the development of the electron theory of metals. It also summarizes conclusions of Bohr‘s dissertation from which we can highlight that classical mechanics is ineffective for objects at the atomic level., Kateřina Šraitrová., and Obsahuje seznam literatury
This article describes a new concept evolution to the simulation process of cutting tool size abrasion with subsequent element of correction in limits of parametrically defined optimal feeding. It deals only with one aspect concerning the polynomial transformation of experimentally obtained discrete values of cutter head position and their integration into continuous functional form compatible with used software environment. and Príspevok popisuje vývoj nového prístupu k simulácii procesu rozmerového opotrebenia rezného nástroja s následným prvkom korekcie v limitných medziach parametricky stanovených optimálnych posuvoch. Článok popisuje len jeden aspekt prislúchajúci polynomickej transformácií experimentálne stanovených diskrétnych hodnôt polohy hrotu noža a ich následnú integritu do spojitej funkcionálnej podoby, kompatibilnej s používaným softwarovým prostredím.
a1_We hypothesize that hypokalemia-related electrolyte imbalance linked with abnormal elevation of intracellular free Ca2+ concentration can cause metabolic disturbances and subcellular alterations resulting in intercellular uncoupling, which favor the occurrence of malignant arrhythmias. Langendorff-perfused guinea pig heart (n = 44) was subjected to a standard Tyrode solution (2.8 mmol/l K+) followed by a K+-deficient solution (1.4 mmol/l K+). Bipolar ECG of the left atria and ventricle was continuously monitored and the incidence of ventricular fibrillation was evaluated. Myocardial tissue sampling was performed during stabilization, hypokalemia and at the onset of fibrillation. Enzyme activities of succinic dehydrogenase, glycogen phosphorylase and 5-nucleotidase were determined using in situ catalytic histochemistry. The main gap junction protein, connexin-43, was labeled using mouse monoclonal antibody and FITC conjugated goat antimouse antibody. Ultrastructure was examined by transmission electron microscopy. The free Ca2+ concentration was measured by the indo-1 method in ventricular cell cultures exposed to a K+-free medium. The results showed that sustained ventricular fibrillation appeared within 15-30 min of low K+ perfusion. This was preceded by ectopic activity, episodes of bigeminy and tachycardia. Hypokalemia induced moderate reversible and sporadically irreversible subcellular alterations of cardiomyocytes and impairment of intercellular junctions, which were heterogeneously distributed throughout myocardium. Patchy areas with decreased enzyme activities and diminished immunoreactivity of connexin-43 were found. Furthermore, lack of external K+ was accompanied by an increase of intracellular Ca2+. The prevention of Ca2+ overload by either 1 mmol/l Ni2+ (Na+/Ca2+ inhibitor), 2.5 mmol/l verapamil, 10 mmol/l d-sotalol or 10 mmol/l tedisamil was associated with the protection agains fibrillation., a2_The results indicate that hypokalemia induces Ca2+ overload injury and disturbances in intercellular coupling. Dispersion of these changes throughout the myocardium may serve as the basis for microreentry circuits and thus favor fibrillation occurrence., N. Tribulová, M. Manoach, D. Varon, L. Okruhlicová, T. Zinman , A. Shainberg., and Obsahuje bibliografii