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31512. Variational measures related to local systems and the Ward property of $\scr P$-adic path bases
- Creator:
- Bongiorno, Donatella , Di Piazza, Luisa, and Skvortsov, Valentin A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- local system, ${\mathcal{P}}$-adic system, differentiation basis, variational measure, and Ward property
- Language:
- English
- Description:
- Some properties of absolutely continuous variational measures associated with local systems of sets are established. The classes of functions generating such measures are described. It is shown by constructing an example that there exists a $\mathcal{P}$-adic path system that defines a differentiation basis which does not possess Ward property.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
31513. Variations in daytime net carbon and water exchange in a montane shrubland ecosystem in southeast Spain
- Creator:
- Serrano-Ortiz, P., Kowalski, A. S. , Domingo, F., Rey, A., Pegoraro, E., Villagarcía, L., and Alados-Arboledas, L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon dioxide flux, eddy covariance, phenology, photon flux density, shrubland, and water vapour flux
- Language:
- Multiple languages
- Description:
- Carbon and water fluxes in a semiarid shrubland ecosystem located in the southeast of Spain (province of Almería) were measured continuously over one year using the eddy covariance technique. We examined the influence of environmental variables on daytime (photosynthetically active photons, FP >10 µmol m-2 s-1) ecosystem gas exchange and tested the ability of an empirical eco-physiological model based on FP to estimate carbon fluxes over the whole year. The daytime ecosystem fluxes showed strong seasonality. During two solstitial periods, summer with warm temperatures (>15 °C) and sufficient soil moisture (>10 % vol.) and winter with mild temperatures (>5 °C) and high soil moisture contents (>15 % vol.), the photosynthetic rate was higher than the daytime respiration rate and mean daytime CO2 fluxes were ca. -1.75 and -0.60 µmol m-2 s-1, respectively. Daytime evapotranspiration fluxes averaged ca. 2.20 and 0.24 mmol m-2 s-1, respectively. By contrast, in summer and early autumn with warm daytime temperatures (>10 °C) and dry soil (<10 % vol.), and also in mid-winter with near-freezing daytime temperatures the shrubland behaved as a net carbon source (mean daytime CO2 release of ca. 0.60 and 0.20 µmol m-2 s-1, respectively). Furthermore, the comparison of water and carbon fluxes over a week in June 2004 and June 2005 suggests that the timing-rather than amount-of spring rainfall may be crucial in determining growing season water and carbon exchange. Due to strongly limiting environmental variables other than FP, the model applied here failed to describe daytime carbon exchange only as a function of FP and could not be used over most of the year to fill gaps in the data. and P. Serrano-Ortiz ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31514. Variations in leaf respiration across different seasons for Mediterranean evergreen species
- Creator:
- Catoni, R., Varone, L., and Gratani, L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, drought, leaf respiration, Mediterranean evergreen species, water stress, 2, and 58
- Language:
- Multiple languages
- Description:
- Leaf respiration (R L) of evergreen species co-occurring in the Mediterranean maquis developing along the Latium coast was analyzed. The results on the whole showed that the considered evergreen species had the same R L trend during the year, with the lowest rates [0.83 ± 0.43 μmol(CO2) m-2 s-1, mean value of the considered species] in winter, in response to low air temperatures. Higher R L were reached in spring [2.44 ± 1.00 μmol(CO2) m-2 s-1, mean value] during the favorable period, and in summer [3.17 ± 0.89 μmol(CO2) m-2 s-1] during drought. The results of the regression analysis showed that 42% of R L variations depended on mean air temperature and 13% on total monthly rainfall. Among the considered species, C. incanus, was characterized by the highest R L in drought [4.93 ± 0.27 μmol(CO2) m-2 s-1], low leaf water potential at predawn (Ψpd = -1.08 ± 0.18 MPa) and midday (Ψmd = -2.75 ± 0.11 MPa) and low relative water content at predawn (RWCpd = 80.5 ± 3.4%) and midday (RWCmd = 67.1 ± 4.6%). Compared to C. incanus, the sclerophyllous species (Q. ilex, P. latifolia, P. lentiscus, A. unedo) and the liana (S. aspera), had lower R L [2.72 ± 0.66 μmol(CO2) m-2 s-1, mean value of the considered species], higher RWCpd (91.8 ± 1.8%), RWCmd (82.4 ± 3.2%), Ψpd (-0.65 ± 0.28 MPa) and Ψmd (-2.85 ± 1.20 MPa) in drought. The narrow-leaved species (E. multiflora, R. officinalis, and E. arborea) were in the middle. The coefficients, proportional to the respiration increase for each 10°C rise (Q10), ranging from 1.49 (E. arborea) to 1.98 (A. unedo) were indicative of the different sensitivities of the considered species to air temperature variation., R. Catoni, L. Varone, and L. Gratani., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31515. Variations in light energy dissipation in Woodfordia fruticosa leaves during expansion
- Creator:
- Zhang, S.-B. and Zhang, J.-L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- anthocyanin, leaf expansion, nonphotochemical quenching, gas exchange, photosynthetic electron flow, photorespiration, 2, and 581
- Language:
- Multiple languages
- Description:
- Young leaves of tropical trees frequently appear red in color, with the redness disappearing as the leaves mature. During leaf expansion, plants may employ photoprotective mechanisms to cope with high light intensities; however, the variations in anthocyanin contents, nonphotochemical quenching (NPQ), and photorespiration during leaf expansion are poorly understood. Here, we investigated pigment contents, gas exchange, and chlorophyll (Chl) fluorescence in Woodfordia fruticosa leaves during their expansion. Young red leaves had significantly lower Chl content than that of expanding or mature leaves, but they accumulated significantly higher anthocyanins and dissipated more excited light energy through NPQ. As the leaves matured, net photosynthetic rate, total electron flow through PSII, and electron flow for ribulose-1,5-bisphosphate oxygenation gradually increased. Our results provided evidence that photorespiration is of fundamental importance in regulating the photosynthetic electron flow and CO2 assimilation during leaf expansion., S.-B. Zhang, J.-L. Zhang., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31516. Variations in photosynthetic rate and associated parameters with age of oil palm leaves under irrigation
- Creator:
- Suresh, K. and Nagamani, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- area leaf mass, chlorophyll, Elaeis, leaf area, leaf dry mass, stomatal conductance, and transpiration rate
- Language:
- Multiple languages
- Description:
- Net photosynthetic rate (PN), transpiration rate (E), and stomatal conductance (gs) in an adult oil palm (Elaeis guineensis) canopy were highest in the 9th leaf and progressively declined with leaf age. Larger leaf area (LA) and leaf dry mass (LDM) were recorded in middle leaves. PN showed a significant positive correlation with gs and a negative relationship with leaf mass per area (ALM). The oil palm leaf remains photosynthetically active for a longer time in the canopy which contributes significantly to larger dry matter production in general and greater fresh fruit bunch yields in particular. and K. Suresh, C. Nagamani.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31517. Variations of leaf morphology, photosynthetic traits and water-use efficiency in Western-Mediterranean tomato landraces
- Creator:
- Fullana-Pericàs, M., Conesa, M. À., Soler, S., Ribas-Carbó, M., Granell, A., and Galmés, J.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- asimilace uhlíku, izotopové složení uhlíku, difúzní omezen, morfologie listu, efektivita využívání vody, rajče, carbon assimilation, carbon isotope composition, diffusive limitations, mesophyll conductance, leaf morphology, water-use efficiency, tomato, 2, and 581
- Language:
- Multiple languages
- Description:
- Modern tomato (Solanum lycopersicum L.) breeding has mainly focused on increasing productivity under unlimited watering. In contrast, some Mediterranean accessions have been traditionally cultivated under water shortage and selected on the basis of their water-use efficiency (WUE). Ramellet and Penjar landraces were planted with other traditional, old and modern inbreeds, under full irrigation. In order to found differences between the tomato accessions, gas-exchange and leaf morphology measurements were performed. Despite high variability, Ramellet and Penjar presented clear differences compared to modern cultivars, mostly related to leaf morphology and photosynthetic traits, while no differences were found in WUE. Results highlighted that better leaf CO2 conductance might be a main factor determining the improvement of net CO2 assimilation and WUE., M. Fullana-Pericàs, M. À. Conesa, S. Soler, M. Ribas-Carbó, A. Granell, J. Galmés., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31518. Variations on undirected graphical models and their relationships
- Creator:
- Heckerman, David, Meek, Christopher, and Richardson, Thomas S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- graphical model, undirected graph, Markov properties, Gibbs sampler, conditionally specified distributions, and dependency network
- Language:
- English
- Description:
- We compare alternative definitions of undirected graphical models for discrete, finite variables. Lauritzen \cite{Lauritzen:1996} provides several definitions of such models and describes their relationships. He shows that the definitions agree only when joint distributions represented by the models are limited to strictly positive distributions. Heckerman et al. \cite{Heckerman_et_al:2000}, in their paper on dependency networks, describe another definition of undirected graphical models for strictly positive distributions. They show that this definition agrees with those of Lauritzen \cite{Lauritzen:1996} again when distributions are strictly positive. In this paper, we extend the definition of Heckerman et al. \cite{Heckerman_et_al:2000} to arbitrary distributions and show how this definition relates to those of Lauritzen \cite{Lauritzen:1996} in the general case.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
31519. Varieties of half lattice-ordered groups of monotonic permutations of chains
- Creator:
- Giraudet, Michèle and Rachůnek, Jiří
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- math, lattice-ordered groups, and monotonic permutations of chains
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
31520. Varieties of idempotent slim groupoids
- Creator:
- Ježek, Jaroslav
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- groupoid, variety, and nonfinitely based
- Language:
- English
- Description:
- Idempotent slim groupoids are groupoids satisfying $xx\=x$ and $x(yz)\=xz$. We prove that the variety of idempotent slim groupoids has uncountably many subvarieties. We find a four-element, inherently nonfinitely based idempotent slim groupoid; the variety generated by this groupoid has only finitely many subvarieties. We investigate free objects in some varieties of idempotent slim groupoids determined by permutational equations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public