Results 21 to 30 of about 290 (63)

Spaces of Test Functions via the STFT

open access: yesJournal of Function Spaces, Volume 2, Issue 1, Page 25-53, 2004., 2004
We characterize several classes of test functions, among them Björck′s ultra‐rapidly decaying test functions and the Gelfand‐Shilov spaces of type S, in terms of the decay of their short‐time Fourier transform and in terms of their Gabor coefficients.
Karlheinz Gröchenig   +2 more
wiley   +1 more source

A trace inequality for generalized potentials in Lebesgue spaces with variable exponent

open access: yesJournal of Function Spaces, Volume 2, Issue 1, Page 55-69, 2004., 2004
A trace inequality for the generalized Riesz potentials Iα(x) is established in spaces Lp(x) defined on spaces of homogeneous type. The results are new even in the case of Euclidean spaces. As a corollary a criterion for a two‐weighted inequality in classical Lebesgue spaces for potentials Iα(x) defined on fractal sets is derived.
David E. Edmunds   +3 more
wiley   +1 more source

The projection operator in a Hilbert space and its directional derivative. Consequences for the theory of projected dynamical systems

open access: yesJournal of Function Spaces, Volume 2, Issue 1, Page 71-95, 2004., 2004
In the first part of this paper we present a representation theorem for the directional derivative of the metric projection operator in an arbitrary Hilbert space. As a consequence of the representation theorem, we present in the second part the development of the theory of projected dynamical systems in infinite dimensional Hilbert space. We show that
George Isac   +2 more
wiley   +1 more source

Note on the paper “Regulated domains and Bergman type projections”

open access: yesJournal of Function Spaces, Volume 2, Issue 2, Page 97-106, 2004., 2004
We show that the sufficient condition of the above mentioned paper is also necessary for the boundedness of Bergman type projections on a class of regulated domains.
Jari Taskinen, Miroslav Englis
wiley   +1 more source

Pseudodifferential operators on α‐modulation spaces

open access: yesJournal of Function Spaces, Volume 2, Issue 2, Page 107-123, 2004., 2004
We study expansions of pseudodifferential operators from the Hörmander class in a special family of functions called brushlets. We prove that such operators have a sparse representation in a brushlet system. Using this sparsity, we show that a pseudodifferential operator extends to a bounded operator between α‐modulation spaces.
Lasse Borup, Richard Rochberg
wiley   +1 more source

Local uniform convexity and Kadec‐Klee type properties in K‐interpolation spaces I: General Theory

open access: yesJournal of Function Spaces, Volume 2, Issue 2, Page 125-173, 2004., 2004
We present a systematic study of the interpolation of local uniform convexity and Kadec‐Klee type properties in K‐interpolation spaces. Using properties of the K‐functional of J.Peetre, our approach is based on a detailed analysis of properties of a Banach couple and properties of a K‐interpolation functional which guarantee that a given K ...
Peter G. Dodds   +4 more
wiley   +1 more source

The Hadamard‐Schwarz inequality

open access: yesJournal of Function Spaces, Volume 2, Issue 2, Page 191-215, 2004., 2004
Given α1, …, αk arbitrary exterior forms in Rn of degree l1, …, lk, does it follow that |α1∧⋯∧αk| ≤ |α1| ⋯ |αk| The answer is no in general. However, it is a persistent, popular and even published misconception that the answer is yes. Of course, a routine calculation reveals that there exists at least a constant Cn independent of the forms satisfying ...
Tadeusz Iwaniec   +4 more
wiley   +1 more source

Quantitative functional calculus in Sobolev spaces

open access: yesJournal of Function Spaces, Volume 2, Issue 3, Page 279-321, 2004., 2004
In the frame work of Sobolev (Bessel potential) spaces Hn(Rd, R or C), we consider the nonlinear Nemytskij operator sending a function x ∈ Rd ↦ f(x) into a composite function x ∈ Rd ↦ G(f(x), x). Assuming sufficient smoothness for G, we give a “tame” bound on the Hn norm of this composite function in terms of a linear function of the Hn norm of f, with
Carlo Morosi   +2 more
wiley   +1 more source

Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants

open access: yesThe Lancet, 2016
Summary Background Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences ...
M. Cesare   +499 more
semanticscholar   +1 more source

Local Uniform Convexity and Kadec‐Klee Type Properties in K‐interpolation spaces II

open access: yesJournal of Function Spaces, Volume 2, Issue 3, Page 323-356, 2004., 2004
We study local uniform convexity and Kadec‐Klee type properties in K‐interpolation spaces of Lorentz couples. We show that a wide class of Banach couples of (commutative and) non‐commutative Lorentz spaces possess the (so‐alled) (DGL)‐property originally introduced by Davis, Ghoussoub and Lindenstrauss in the context of renorming order continuous ...
Peter G. Dodds   +4 more
wiley   +1 more source
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