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Start Over Coverage 215-222

2. Estimates of the principal eigenvalue of the p-Laplacian and the p-biharmonic operator

Creator:
Benedikt, Jiří
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
eigenvalue problem for p-Laplacian, eigenvalue problem for p-biharmonic operator, estimates of principal eigenvalue, and asymptotic analysis
Language:
English
Description:
We survey recent results concerning estimates of the principal eigenvalue of the Dirichlet p-Laplacian and the Navier p-biharmonic operator on a ball of radius R in R N and its asymptotics for p approaching 1 and ∞. Let p tend to ∞. There is a critical radius RC of the ball such that the principal eigenvalue goes to ∞ for 0 < R 6 RC and to 0 for R > RC . The critical radius is RC = 1 for any N ∈ N for the p-Laplacian and RC = √ 2N in the case of the p-biharmonic operator. When p approaches 1, the principal eigenvalue of the Dirichlet p-Laplacian is NR−1 × (1− (p − 1) log R(p − 1)) + o(p − 1) while the asymptotics for the principal eigenvalue of the Navier p-biharmonic operator reads 2N/R2 + O(−(p − 1) log(p − 1)).
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Maize photosynthesis and microclimate within the canopies at grain-filling stage in response to narrow-wide row planting patterns

Creator:
Liu, T. D. and Song, F. B.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, maize, microclimate, photosynthesis, planting pattern, 2, and 58
Language:
Multiple languages
Description:
In China, narrow-wide row planting pattern has been advocated for maize (Zea mays L.) production. However, no previous study has clearly elucidated the complexity of factors affecting maize canopy such as the microclimatic factors, and the effect of photosynthesis in narrow-wide row planting pattern. The current study was undertaken to identify the planting patterns that influence microclimatic conditions and photosynthesis of two maize cultivars (Beiyu288 and Xianyu335) grown in three planting patterns: narrow-wide rows of (1) 30 cm + 170 cm (P1, 6.4 plants m-2), and (2) 40 cm + 90 cm (P2, 6.4 plants m-2), and (3) uniform row of 65 cm (CK, conventional row as control, 6.4 plants m-2). Light interception, temperature, relative humidity (RH), CO2 concentration, and leaf photosynthesis within the canopy were measured in each planting treatment at the grain-filling stage. The net photosynthetic rate (PN), intercellular CO2 concentration (Ci), stomatal conductance (gs), transpiration rate (E), and temperature of the narrow-wide row exceeded that of the conventional row. The CO2 concentration and RH of the narrow-wide row were lower than CK by 50 cm strata. The narrow-wide row had a more uniform light intercepted at the whole canopy profile. The results of the current study suggest that narrow-wide row-planting pattern has a positive effect on canopy microclimate factors and promotes photosynthesis., T. D. Liu, F. B. Song., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Photosynthesis and water relations of well-watered orange plants as affected by winter and summer conditions

Creator:
Ribeiro, R. V., Machado, E. C., Santos, M. G., and Oliveira, R. F.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Citrus sinensis, chlorophyll fluorescence, ecophysiology, gas exchange, and seasonality
Language:
Multiple languages
Description:
The aim of this study was to evaluate how the summer and winter conditions affect the photosynthesis and water relations of well-watered orange trees, considering the diurnal changes in leaf gas exchange, chlorophyll (Chl) fluorescence, and leaf water potential (Ψ) of potted-plants growing in a subtropical climate. The diurnal pattern of photosynthesis in young citrus trees was not significantly affected by the environmental changes when compared the summer and winter seasons. However, citrus plants showed higher photosynthetic performance in summer, when plants fixed 2.9 times more CO2 during the diurnal period than in the winter season. Curiously, the winter conditions were more favorable to photosynthesis of citrus plants, when considering the air temperature (< 29 °C), leaf-to-air vapor pressure difference (< 2.4 kPa) and photon flux density (maximum values near light saturation) during the diurnal period. Therefore, low night temperature was the main environmental element changing the photosynthetic performance and water relations of well-watered plants during winter. Lower whole-plant hydraulic conductance, lower shoot hydration and lower stomatal conductance were noticed during winter when compared to the summer season. In winter, higher ratio between the apparent electron transport rate and leaf CO2 assimilation was verified in afternoon, indicating reduction in electron use efficiency by photosynthesis. The high radiation loading in the summer season did not impair the citrus photochemistry, being photoprotective mechanisms active. Such mechanisms were related to increases in the heat dissipation of excessive light energy at the PSII level and to other metabolic processes consuming electrons, which impede the citrus photoinhibition under high light conditions. and R. V. Ribeiro ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public