To investigate the effects of atmospheric CO2 enrichment on physiology and autumnal leaf phenology, we exposed 3-year-old sugar maple (Acer saccharum Marsh.) seedlings to 800 (A8), 600 (A6), and 400 μL(CO2) L-1 (AA) in nine continuous stirred tank reactor (CSTR) chambers during the growing season of 2014. Leaf abscission timing, abscised leaf area percentages, leaf number, light-saturated net photosynthetic rate (PNmax), leaf area, accumulative growth rates, and biomass were determined and assessed. The results suggested the following: (1) no significant differences were found in the timing of leaf abscission in the three CO2-concentration treatments; (2) PNmax was continuously stimulated to the greatest extent in A8 at 319% and 160% in A6 until the end of the growing season, respectively; and (3) leaf number, leaf area, and accumulative height growth all significantly increased by elevated CO2, which led to a 323% increase in A8 biomass and 235% in A6 biomass after 156-d fumigation. In summary, the results suggest, the timing of leaf abscission of sugar maple in fall was not modified by CO2 enrichment, the increased carbon gain by elevated CO2 was mainly due to increased leaf area, more leaves, and the continuously enhanced high photosynthesis throughout the growing season instead of the leaf life span., L. Li, W. J. Manning, X. K. Wang., and Obsahuje bibliografii
Basic methods of the sensitivity analysis applicable in combination with numerical Monte Carlo type simulation methods are presented in the paper. An example of the influence of a plane steel fame initial imperfections on its load-carrying capacity variability is given there. It is shown in this paper that basic sensitivity analysis methods can be inaccurate in some cases. The updated modification of the procedures mentioned is proposed so that it were possible to apply them to the most various structure types solved by means of simulation methods. The influence of initial imperfections on the load-carrying capacity of steel plane frame is analysed by auxiliary sensitivity analysis. The realisations of input random quantities were simulated by the Latin Hypercube Sampling method. The load-carrying capacity was solved by geometrically and materially nonlinear solution. and Obsahuje seznam literatury
The effects of awn removal on ear gas exchange in four barley lines (Morex, Harrington, Steptoe, and TR306) were studied under a controlled environment using a Before-After Control-Impact Paired (BACIP) experimental design. From ear emergence to grain maturity, plants were grown in pots at either 60 or 90 % of soil water holding capacity. Gas-exchange measurements of ears were made 9 and 10 d after anthesis (DAA). On 11 DAA, awn removal was performed on half of the ears in each pot, followed by measurements on both intact and de-awned ears on 12 and 13 DAA. Net photosynthetic (PN) and transpiration (E) rates decreased significantly with awn removal, but dark respiration (RD) rate was not affected. We estimated for each ear a temperature-adjusted respiration rate (Ra) from RD. When we corrected PN with Ra, we found that rates of spikelet photosynthesis were largely underestimated. Moderate water stress had minimal effect on gas exchange of bracts and awns of the barley ear. Barley lines did not differ for any individual gas-exchange parameter. and Q. Z. Jiang ... [et al.].
Monstrozní, obří, tajemné, vražedné, vymykající se známým fyzikálním zákonům, přímo nepozorovatelné brány do jiných vesmírů... Jen málokteré objekty v kosmu se honosí tak barvitými a rozpruplnými označeními jako černé díry. A současně málokteré tolik dráždí zvědavost nejen veřejnosti, ale také astronomů, kosmologů a (astro)fyziků, kteří se snaží kousek po kousku odrhrnout roušku jejich tajemství. Černé díry se však nehodlají vzdát a vzdorovitě připravují jedno překvapení za druhým. and Jana Olivová, Michal Švanda.
The behaviour of B-chromosomes in meiosis was studied in 44 males of yellow- necked mouse, Apodemus flavicollis. The Bs behave in a non-Mendelian fashion during meiosis I i.e., appear as univalents, regardless of the number of Bs, and segregate in a random fashion. The meiotic drag of Bs, resulting from Bs lagging and premature division of Bs into chromatids, was found in 1B animals. The Bs drag amounts to about 6% of cells and is not substantial; however due to dispensable nature of Bs, it has to be compensated through drive in females or heterotic effects of Bs. This result gives support for the heterotic model of Bs evolution in A. flavicollis. On the other hand, the number of chiasmata on A-chromosomes showed increasing tendency with the number of Bs in the karyotype. As the chiasma effect is characteristic for parasitic Bs, it gives support for the parasitic model of Bs evolution. With contrasting results, the hypothesis of a combined model of Bs evolution, in which the fitness of B-bearers changes around the year or in different environmental conditions is discussed.