763 research outputs found
Abscission of grapevine fruitlets in relation to ethylene biosynthesis
The ethylene content of grapevine (Vitis vinifera, cv. Chardonnay) flowers and fruitlets was followed during flowering, i.e. from stage 18 to stage 32 (EICHHORN and LORENZ 1977). A strong rise of ethylene was observed at the beginning of abscission, corresponding to stage 23. High levels of ethylene were found in the whole period in which abscission occurred, indicating a possible role of ethylene in grapevine fruitlet abscission. The rise of ethylene was associated with a rise of 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC oxidase activity. At the end of abscission (stage 28-29), the levels of ethylene, ACC and ACC oxidase activity decreased to a level close to that at pre-bloom. The ethylene evolution in two clones with different sensitivity to berry drop revealed the relationship between ethylene and the intensity of abscission, and confirmed that the abscission promoting effect of ethylene depends on the phenological stage. Results are discussed with regard to possible hormonal interactions between ethylene, ACC, ACC oxidase and abscisic acid.
Electron Wave Filters from Inverse Scattering Theory
Semiconductor heterostructures with prescribed energy dependence of the
transmittance can be designed by combining: {\em a)} Pad\'e approximant
reconstruction of the S-matrix; {\em b)} inverse scattering theory for
Schro\"dinger's equation; {\em c)} a unitary transformation which takes into
account the variable mass effects. The resultant continuous concentration
profile can be digitized into an easily realizable rectangular-wells structure.
For illustration, we give the specifications of a 2 narrow band-pass 12 layer
filter with the high energy peak more than {\em twice
narrower} than the other.Comment: 4 pages, Revtex with one eps figur
An exploratory social network analysis of academic research networks
For several decades, academics around the world have been collaborating with the view to support the development of their research domain. Having said that, the majority of scientific and technological policies try to encourage the creation of strong inter-related research groups in order to improve the efficiency of research outcomes and subsequently research funding allocation. In this paper, we attempt to highlight and thus, to demonstrate how these collaborative networks are developing in practice. To achieve this, we have developed an automated tool for extracting data about joint article publications and analyzing them from the perspective of social network analysis. In this case study, we have limited data from works published in 2010 by England academic and research institutions. The outcomes of this work can help policy makers in realising the current status of research collaborative networks in England
In vitro morphogenesis of grapevine (Vitis vinifera L.) originated from anticipated or latent buds
While in outdoor-grown vines shoots originate from latent buds, grapevine shoots from microcuttings cultured in vitro are produced by the anticipated bud. The latter shoots show physiological and morphological features of juvenility. This study was carried out to obtain more conform in vitro grapevine shoots. Latent buds were induced to develop in vitro. Shoots produced by latent buds had more juvenile features than those produced by anticipated buds. New information on the control of juvenility of grapevines in vitro is presented
Vertical and horizontal elasticity for dynamic virtual machine reconfiguration
Today, cloud computing applications are rapidly constructed by services belonging to different cloud providers and service owners. This work presents the inter-cloud elasticity framework, which focuses on cloud load balancing based on dynamic virtual machine reconfiguration when variations on load or on user requests volume are observed. We design a dynamic reconfiguration system, called inter-cloud load balancer (ICLB), that allows scaling up or down the virtual resources (thus providing automatized elasticity), by eliminating service downtimes and communication failures. It includes an inter-cloud load balancer for distributing incoming user HTTP traffic across multiple instances of inter-cloud applications and services and we perform dynamic reconfiguration of resources according to the real time requirements. The experimental analysis includes different topologies by showing how real-time traffic variation (using real world workloads) affects resource utilization and by achieving better resource usage in inter-cloud
The potential relationship of stilbene (resveratrol) synthesis to anthocyanin content in grape berry skins
The relationship between the production of resveratrol, a phytoalexin related to grape disease resistance, and the anthocyanin content of grape berries in diverse Vitis species has been investigated. Previous studies have reported that the phytoalexin production potential of grapes suddenly declines at veraison. The results obtained here from assaying resveratrol and anthocyanins from grape berries in different developmental stages suggest that chalcone synthase (EC 2.3.1.74), the key enzyme involved in anthocyanin biosynthesis, may compete with stilbene (resveratrol) synthase (EC 2.3.1.-), such that the decrease of the ability of grapes to synthesize resveratrol in response to UV-irradiation observed after the onset of fruit ripening may be a consequence of the concomitant rise of anthocyanin accumulation in fruits
L'organogènese inflorescentielle dans les bourgeons anticipÊs de vigne (Vitis vinifera L. cÊpage Pinot)
Organogenesis of inflorescences in the lateral buds of grapevine (Vitis vinifera L. cv. Pinot)The formation of inflorescences in lateral buds has been investigated by studies of longitudinal sections of paraffin-embedded lateral buds. The lateral buds at position 6 (from the base) were collected from non-decapitated shoots, from the middle of May to the end of June. The different developmental stages of inflorescence and also a chronological analysis have been described. The observations inform about the organogenetic ch aracteristics which occur in the absence of decapitation of the main shoot
Lyashko-Looijenga morphisms and submaximal factorisations of a Coxeter element
When W is a finite reflection group, the noncrossing partition lattice NCP_W
of type W is a rich combinatorial object, extending the notion of noncrossing
partitions of an n-gon. A formula (for which the only known proofs are
case-by-case) expresses the number of multichains of a given length in NCP_W as
a generalised Fuss-Catalan number, depending on the invariant degrees of W. We
describe how to understand some specifications of this formula in a case-free
way, using an interpretation of the chains of NCP_W as fibers of a
Lyashko-Looijenga covering (LL), constructed from the geometry of the
discriminant hypersurface of W. We study algebraically the map LL, describing
the factorisations of its discriminant and its Jacobian. As byproducts, we
generalise a formula stated by K. Saito for real reflection groups, and we
deduce new enumeration formulas for certain factorisations of a Coxeter element
of W.Comment: 18 pages. Version 2 : corrected typos and improved presentation.
Version 3 : corrected typos, added illustrated example. To appear in Journal
of Algebraic Combinatoric
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