2,464 research outputs found
A multivariate regional test for detection of trends in extreme rainfall: the case of extreme daily rainfall in the French Mediterranean area
In this paper we present a multivariate regional test we developed for the
detection of trends in extreme rainfall, which takes into account the
spatial dependence between rainfall measurements with copula functions. The
test is based on four steps. It was applied to a set of 92 series of Annual
Daily Maxima (ADM) rainfall in the French Mediterranean area, sampled during
the 1949–2004 observation period. The results show a low significant trend,
concerning mainly the mountains area in the west part of the French
Mediterranean region. The position's parameters of the ADM rainfall
probability distribution functions present a low but significant increasing
trend of about 5% to 10%, the same increase as that observed in ADM
rainfall quantiles in the last 56 years. Further work is needed
to understand if this significative trend is related to the global climate
change or to the natural variability of Mediterranean climate
On the Nonlocal Equations and Nonlocal Charges Associated with the Harry Dym Hierarchy
A large class of nonlocal equations and nonlocal charges for the Harry Dym
hierarchy is exhibited. They are obtained from nonlocal Casimirs associated
with its bi-Hamiltonian structure. The Lax representation for some of these
equations is also given.Comment: to appear in Journal of Mathematical Physics, 17 pages, Late
Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach
Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations
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
Advancing our understanding of the EU sports policy: the socio-cultural model of sports regulation and players’ agents
This paper explains the development of the socio-cultural dimension of the European Union (EU) sports policy over the course of the decade from 2005 to 2015. By adopting the theoretical lenses of the Advocacy Coalition Framework (ACF), the paper firstly offers a novel perspective on the belief systems of the members of the socio-cultural advocacy coalition that operates within the EU sports policy subsystem. A set of empirical policy core beliefs of the coalition actors reflecting their concerns regarding to sport’s integrity and economic welfare that affect its healthy development is presented and explained as the basic causes of the policy problem, i.e., threats that undermine sport’s specific characteristics. In this light, the paper then illustrates that the coalition members have perceived the issue of players’ agents, in particular problems in the activities of agents in European football, to be detrimental to the integrity of sport. As a result, the issue has been the subject of a considerable policy activity by the coalition actors with a view to establishing an alternative regulatory framework to effectively govern players’ agents. Consequently, the paper elucidates the evolving nature of the socio-cultural model of sports regulation that not only promotes the social role of sport in Europe but now also addresses the problems that affect its well-being and clear image. The paper’s principal method of investigation is based on the content analysis of official policy documents and statements of the coalition actors
Use of specific Green's functions for solving direct problems involving a heterogeneous rigid frame porous medium slab solicited by acoustic waves
A domain integral method employing a specific Green's function (i.e.,
incorporating some features of the global problem of wave propagation in an
inhomogeneous medium) is developed for solving direct and inverse scattering
problems relative to slab-like macroscopically inhomogeneous porous obstacles.
It is shown how to numerically solve such problems, involving both
spatially-varying density and compressibility, by means of an iterative scheme
initialized with a Born approximation. A numerical solution is obtained for a
canonical problem involving a two-layer slab.Comment: submitted to Math.Meth.Appl.Sc
Nonlinear Evolution Equations Invariant Under Schroedinger Group in three-dimensional Space-time
A classification of all possible realizations of the Galilei,
Galilei-similitude and Schroedinger Lie algebras in three-dimensional
space-time in terms of vector fields under the action of the group of local
diffeomorphisms of the space \R^3\times\C is presented. Using this result a
variety of general second order evolution equations invariant under the
corresponding groups are constructed and their physical significance are
discussed
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