Cílem projektu Mimosa je zjistit podrobnosti o dynamice těch umělých družic pohybujících se v těsné blízkosti Země, ve výškách od 150 do 1000 km. Praktické využití tohoto druhu umělých těles je stále častější a žádanější, především pro dálkový průzkum, telekomunikace, meteorologii, pro vojenské účely a také pro základní výzkum tvaru a vlastností zemského tělesa. Vliv vysoké atmosféry na pohyb takových těles není zanedbatelný a účinky dalších negravitačních sil, především radiačního původu - přímé záření sluneční, záření odražené od zemského povrchu, tepelné vyzařování Země jsou rovněž podstatné pro sledování (a zvláště předpovídání) dráhového pohybu a rotace družic. K tomu se řadí i vlastní infračervené vyzařování tělesa družice a elektromagnetické vlivy zemského magnetického pole na elektricky nabitou družici. Pro popis působení těchto sil na pohyb umělých družic a pro následné co nejpřesnější určení jejich polohy a dráhy je nutno získat kvalitní a časté údaje, nejlépe měřením jejich dynamického účinku akcelerometry. Proto byl navržen projekt Mimosa, který se týká umělé družice blízké Zemi, nesoucí na palubě vysoce citlivý akcelerometr. Tento přístroj byl již vyzkoušen na oběžné dráze s velmi příznivými výsledky. Družice s mikroakcelerometrem je již ve fázi předstartovní přípravy. Start se má uskutečnit pomocí rakety ROKOT z ruského kosmodromu Plesetsk, podle současných údajů německo-ruské společnosti EUROCKOT, odpovědné za realizaci startu, v dubnu roku 2003. V hlavním článku jsou popsány cíle projektu a podrobnosti. and Ladislav Sehnal.
Rain gauges, weather radars, satellite sensors and modelled data from weather centres are used operationally for estimating the spatial-temporal variability of rainfall. However, the associated uncertainties can be very high, especially in poorly equipped regions of the world. Very recently, an innovative method, named SM2RAIN, that uses soil moisture observations to infer rainfall, has been proposed by Brocca et al. (2013) with very promising results when applied with in situ and satellite-derived data. However, a thorough analysis of the physical consistency of the SM2RAIN algorithm has not been carried out yet. In this study, synthetic soil moisture data generated from a physically-based soil water balance model are employed to check the reliability of the assumptions made in the SM2RAIN algorithm. Next, high quality and multiyear in situ soil moisture observations, at different depths (5-30 cm), and rainfall for ten sites across Europe are used for testing the performance of the algorithm, its limitations and applicability range. SM2RAIN shows very high accuracy in the synthetic experiments with a correlation coefficient, R, between synthetically generated and simulated data, at daily time step, higher than 0.940 and an average Bias lower than 4%. When real datasets are used, the agreement between observed and simulated daily rainfall is slightly lower with average R-values equal to 0.87 and 0.85 in the calibration and validation periods, respectively. Overall, the performance is found to be better in humid temperate climates and for sensors installed vertically. Interestingly, algorithms of different complexity in the reproduction of the underlying hydrological processes provide similar results. The average contribution of surface runoff and evapotranspiration components amounts to less than 4% of the total rainfall, while the soil moisture variations (63%) and subsurface drainage (30%) terms provide a much higher contribution. Overall, the SM2RAIN algorithm is found to perform well both in the synthetic and real data experiments, thus offering a new and independent source of data for improving rainfall estimation, and consequently enhancing hydrological, meteorological and climatic studies.
Flavonoids are thought to participate in protection of the photosynthetic apparatus against photoinhibition under excessive light. Flavone glycoside, scutellarin, is a main active ingredient extracted from Erigeron breviscapus, the plant used in Chinese medicine. Shade-developed leaves of E. breviscapus were transferred from shade to full sunlight to quantify a relationship between the concentration of leaf scutellarin and tolerance to high radiation stress or the recovery from photoinhibition. The maximal quantum yield of PSII photochemistry showed a diurnal fluctuation in both shaded and sunlit leaves throughout the day. It indicated dynamic photoinhibition in the leaves of Erigeron, i.e., higher photoinhibition at solar noon and lower one in the morning and late afternoon. The sun-developed leaves reached the higher scutellarin content and values of nonphotochemical quenching coefficient with a lower degree of photoinhibition than the shade-developed leaves. When the shade-developed leaves were transferred to full sunlight, the content of scutellarin was declining continuously for 10 d and then was increasing for 15 d. After 50 d, all leaves became the sun-developed leaves with their scutellarin contents of about 138.5 ± 5.2 mg g-1(dry mass, DM) which was significantly higher than that of the shade-developed leaves [107.8 ± 9.8 mg g-1(DM)]. During acclimatization, the degree of photoinhibition was negatively correlated with the scutellarin content. Our results demonstrated a synchronous fluctuation between the flavonoid content and degree of protection against photoinhibition., R. Zhou, W. H. Su, G. F. Zhang, Y. N. Zhang, X. R. Guo., and Obsahuje seznam literatury
A greenhouse study was performed in order to investigate the effects of three arbuscular mycorrhizal fungi (AMF) species on vegetative growth, water relations, and mineral composition parameters of snapdragon (Antirrhinum majus cv. Bells white) under irrigation from different water sources. Five irrigation treatments included using purely desalinized (fresh) water (DW), as a control, three different blends of DW with saline ground water from a well with increasing salinity, and one with 100% of saline well water. Inoculation with AMF enhanced growth rates and a relative water content of snapdragon plants grown under well-water irrigation. AMF also improved the leaf water potential and increased water-use efficiency of the plants. Shoot and root dry masses were higher in the AMF-treated plants than those in AMF-free plants. In both shoots and roots, concentrations of total P, Ca2+, N, Mg2+, and K+ were higher in the AMF-treated plants compared with AMF-free plants under salt-stress conditions. Shoot Cl- and Na+ concentrations were lower in the AMF-treated plants than those in the AMF-free plants grown under well-water irrigation. Snapdragon plants exhibited a high degree of dependency on AMF; it improved plant growth rates and leaf water relations, particularly, with increasing salinity of irrigation water., Y. I. El-Nashar., and Obsahuje bibliografii