1,237 research outputs found
Constructive updating/downdating of oblique projectors: a generalization of the Gram-Schmidt process
A generalization of the Gram-Schmidt procedure is achieved by providing
equations for updating and downdating oblique projectors. The work is motivated
by the problem of adaptive signal representation outside the orthogonal basis
setting. The proposed techniques are shown to be relevant to the problem of
discriminating signals produced by different phenomena when the order of the
signal model needs to be adjusted.Comment: As it will appear in Journal of Physics A: Mathematical and
Theoretical (2007
Measurements design and phenomena discrimination
The construction of measurements suitable for discriminating signal
components produced by phenomena of different types is considered. The required
measurements should be capable of cancelling out those signal components which
are to be ignored when focusing on a phenomenon of interest. Under the
hypothesis that the subspaces hosting the signal components produced by each
phenomenon are complementary, their discrimination is accomplished by
measurements giving rise to the appropriate oblique projector operator. The
subspace onto which the operator should project is selected by nonlinear
techniques in line with adaptive pursuit strategies
On the truncation of the harmonic oscillator wavepacket
We present an interesting result regarding the implication of truncating the
wavepacket of the harmonic oscillator. We show that disregarding the
non-significant tails of a function which is the superposition of
eigenfunctions of the harmonic oscillator has a remarkable consequence: namely,
there exist infinitely many different superpositions giving rise to the same
function on the interval. Uniqueness, in the case of a wavepacket, is restored
by a postulate of quantum mechanics
On the existence and asymptotic stability of solutions for unsteady mixing-layer models
We introduce in this paper some elements for the mathematical analysis of turbulence models for oceanic surface mixing layers. We consider Richardson-number based vertical eddy diffusion models. We prove the existence of unsteady solutions if the initial condition is close to an equilibrium, via the inverse function theorem in Banach spaces. We use this result to prove the non-linear asymptotic stability of equilibrium solutions
Metodología para seleccionar tecnologías Web 2.0 para la docencia
Actualmente existe un gran auge en el uso y
difusión de las herramientas Web 2.0 tanto en
el contexto profesional como en el personal.
Su aplicación al ámbito de la docencia, tal y
como sugieren algunos estudios, puede tener
numerosas ventajas. Sin embargo, el abanico
de herramientas Web 2.0 es muy amplio y
por tanto sería de utilidad disponer de una
metodología que pudiera guiar al docente a
la hora de elegir la tecnología más adecuada
a su proceso de enseñanza-aprendizaje según
los objetivos perseguidos, así como en su
implantación y posterior evaluación de los
resultados alcanzados.
En este artículo, se presenta una
metodología de ayuda a los docentes de
cualquier área de conocimiento para la
selección e implantación de la tecnología Web
2.0 que más se adapte a un determinado
proceso de enseñanza-aprendizaje en base a
criterios docentes y técnicos. Esta metodología
es el resultado de un proyecto de mejora e
innovación educativa en el cual se han
llevado a cabo diversas experiencias docentes
sobre la aplicación de herramientas Web
2.0 en asignaturas de distintas titulaciones
universitarias.SUMMARY -- The use and dissemination of Web 2.0
tools in professional and personal context
is becoming more popular every day. Its
application to teaching, as it is suggested by
some studies, may have numerous advantages.
However, the range of Web 2.0 tools is very
broad and it would therefore be useful to
have a methodology that guide the teacher
in choosing the most appropriate technology
to their teaching-learning process, taking into
account some final objectives, as well as
implementing and evaluating the achieved
results.
This paper presents a methodology to
assist teachers from any area of knowledge
in the selection of the Web 2.0 technology
that best suits a particular teaching-learning
process. This selection is based on some
educational and technical criteria. The
presented methodology is the result of an
educational innovation and improvement
project in which various teaching experiences
based on the use of Web 2.0 tools have been
carried out in different subjects of science
degrees.Peer Reviewe
Safety Profile and Tolerability of Topical Phosphodiesterase 4 Inhibitors for the Treatment of Atopic Dermatitis: A Systematic Review and Meta-Analysis
Evaluate the safety profile and tolerability of topical phosphodiesterase 4 (PDE4) inhibitors versus vehicle as treatment for atopic dermatitis in published studies.A search was performed in Medline/PubMed, Web of Science, and Cochrane Library databases on September 27, 2021, by 1 evaluator, without restrictions on publication dates or languages. Terms such as atopic dermatitis, phosphodiesterase 4 inhibitors, calcineurin inhibitors, and randomized controlled trials were included. The database searches were carried out by 1 evaluator. The titles and abstracts were reviewed for the identification and evaluation of potentially eligible studies. Study selection was made by two reviewers, so there was no intra-examiner statistic at the study selection step. The full-text articles were reviewed to determine whether or not they would be included in the systematic review. Global analyses, which included studies with both unclear and low risk of bias and subanalyses of studies with a low risk of bias were performed.Out of 237 identified articles, 14 clinical trials were included in the meta-analysis. In global analyses of studies with low and unclear risk of bias, topical treatment with PDE4 inhibitors did not differ from vehicle treatment in global treatment emergent adverse events (relative risk?=?0.99; 95% CI, 0.87-1.14; P?=?0.94) or in serious emergent adverse events appearance (relative risk?=?0.92; 95% CI, 0.39-2.20; P?=?0.86). In subanalyses of studies with a low risk of bias, a reduced rate of atopic dermatitis exacerbation was observed in PDE4 inhibitors compared with the vehicle (relative risk?=?0.62; 95% CI, 0.39-0.98; P?=?0.04) and risk of pain at the application site was confirmed (relative risk?=?2.59; 95% CI, 1.27-5.28; P?=?0.01).PDE4 inhibitors did not show differences from vehicle treatment in treatment emergent adverse events or serious emergent adverse events incidence. In studies with low risk of bias, PDE4 inhibitors had a statistically significant risk of producing pain and reduced occurrence of atopic dermatitis exacerbation.© 2022 The Author(s)
From cardinal spline wavelet bases to highly coherent dictionaries
Wavelet families arise by scaling and translations of a prototype function, called the mother wavelet. The construction of wavelet bases for cardinal spline spaces is generally carried out within the multi-resolution analysis scheme. Thus, the usual way of increasing the dimension of the multi-resolution subspaces is by augmenting the scaling factor. We show here that, when working on a compact interval, the identical effect can be achieved without changing the wavelet scale but reducing the translation parameter. By such a procedure we generate a redundant frame, called a dictionary, spanning the same spaces as a wavelet basis but with wavelets of broader support. We characterize the correlation of the dictionary elements by measuring their 'coherence' and produce examples illustrating the relevance of highly coherent dictionaries to problems of sparse signal representation
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