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Search Results: 1 - 10 of 402375 matches for " M. Gutierrez "
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M. Gutierrez
Motricidad : European Journal of Human Movement , 2010,
Abstract: Con el presente trabajo se pretende dar una visión general sobre el ciclismo deportivo desde una perspectiva biomecánica, aunque es necesario decir que la extraordinaria dimensión de la vasta producción científica relacionada con el tema, hace que sea realmente difícil abordar, en un solo trabajo, los diferentes aspectos que abarca la biomecánica del ciclismo. Debido a la diversidad de contenidos que incluye la biomecánica del ciclismo, en este trabajo los contenidos se han restringido en tres unidades: la primera, orientada hacia el estudio de las fuerzas que se oponen al desplazamiento y especialmente al análisis de las resistencias aerodinámicas, la segunda, al estudio de las fuerzas propulsivas y especialmente las aplicadas contra el pedal y, por último, orientaremos nuestra atención hacia los aspectos más relevantes que determinan la eficacia mecánica del desplazamiento en ciclismo.
The estimation of the noise in cosmic microwave background anisotropy experiments
C. M. Gutierrez
Physics , 1997, DOI: 10.1086/304241
Abstract: Even the most sensitive cosmic microwave background anisotropy experiments have signal to noise ratios <=5, so that an accurate determination of the properties of the cosmological signal requires a careful assessment of the experimental noise. Most of the experiments combine simultaneous multi-channel observations in which the presence of correlated noise is likely. This case is common for ground-based experiments in which an important fraction of the noise could be atmospheric in origin. Here, the way to compute and determine the effects produced by this correlated noise is discussed; in particular, the paper considers the Tenerife experiments (three radiometers at 10, 15 and 33 GHz with two independent receivers each) showing how this effect has been taking into account properly in the more recent analysis of these data. It will be demonstrated that for each of the three radiometers of these experiments, the atmospheric noise is equivalent to a Gaussian noise common to both channels with a coherence time smaller than the binning time, the net effect being an enhancement of the error-bars in the stacked scan as compared with the estimation for the case of pure uncorrelated noise. As expected from the spectral index of the atmosphere, the effect is more important at higher frequencies. The formalism is generalized and applied to the general case of simultaneous multi-channel observations.
The most distant compact groups
C. M. Gutierrez
Physics , 2011, DOI: 10.1088/2041-8205/737/1/L21
Abstract: We present photometric and spectroscopic observations of the members of three previously cataloged compact group (CG) candidates at redshifts z>0.3. These confirm spectroscopic redshifts compatible with being gravitationally bound structures at redshifts 0.3112, 0.3848 and 0.3643 respectively, and then they are the most distant CGs known with spectroscopic confirmation for all their members. The morphological and spectroscopic properties of all their galaxies indicate early types dominated by an old population of stars, with little star formation or nuclear activity. Most of the physical properties derived for the three groups are quite similar to the average properties of CGs at lower redshifts. In particular, from the velocities and positions of the respective members of each CG, we estimate short dynamic times. These leave open the questions of identifying the mechanism for forming CGs continuously and the nature of the final stages of these structures.
Stationary determinism in Observed Time Series: the earth's surface temperature
Rafael M. Gutierrez
Physics , 1999,
Abstract: In this work we address the feasibility of estimating and isolating the stationary and deterministic content of observational time series, {\bf Ots}, which in general have very limited characteristics. In particular, we study the valuable earth's surface mean temperature time series, {\bf Tts}, by applying several treatments intended to isolate the stationary and deterministic content. We give particular attention to the sensitivity of results on the different parameters involved. The effects of such treatments were assessed by means of several methods designed to estimate the stationarity of time series. In order to strengthen the significance of the results obtained we have created a comparative framework with seven test time series of well-know origin and characteristics with a similar small number of data points. We have obtained a greater understanding of the potential and limitations of the different methods when applied to real world time series. The study of the stationarity and deterministic content of the {\bf Tts} gives useful information about the particular complexity of global climatic evolution and the general important problem of the isolation of a real system from its surroundings by measuring and treating the obtained observations without any other additional information about the system.
A counterrotating central component in NGC 5728
F. Prada,C. M. Gutierrez
Physics , 1999, DOI: 10.1086/307199
Abstract: We present a detailed study of the stellar kinematics in the barred galaxy NGC 5728 based on I-band photometry and long-slit spectroscopic observations in the region of the near-IR Ca II triplet. The analysis of the stellar line-of-sight velocity distribution (LOSVD) has revealed, in the central regions of the bar, the presence of a cold (v/sigma~2.5) prograde $S$-shaped velocity component that coexists in the central 4 kpc with a fainter and hotter (v/sigma~0.5) counterrotating component. Beyond 4 kpc from the nucleus the LOSVD shows the stellar bar kinematics. The comparison of the radial surface brightness profile of the velocity components with that obtained from an I-band image shows that the counterrotating core follows a r^(1/4) profile, while the S-shaped component does not follows the flat bar surface brightness profile. Several possible scenarios accounting for such kinematic signatures found in the center of the bar in NGC 5728 are discussed.
When every polynomial is unconditionally converging
Manuel Gonzalez,Joaquin M. Gutierrez
Mathematics , 1994,
Abstract: Letting $E$, $F$ be Banach spaces, the main two results of this paper are the following: (1) If every (linear bounded) operator $E\rightarrow F$ is unconditionally converging, then every polynomial from $E$ to $F$ is unconditionally converging (definition as in the linear case). (2) If $E$ has the Dunford-Pettis property and every operator $E\rightarrow F$ is weakly compact, then every $k$-linear mapping from $E^k$ into $F$ takes weak Cauchy sequences into norm convergent sequences. In particular, every polynomial from $\ell_\infty$ into a space containing no copy of $\ell_\infty$ is completely continuous. This solves a problem raised by the authors in a previous paper, where they showed that there exist nonweakly compact polynomials from $\ell_\infty$ into any nonreflexive space.
Polynomial Grothendieck properties
Manuel Gonzalez,Joaquin M. Gutierrez
Mathematics , 1994,
Abstract: A Banach space $E$ has the Grothendieck property if every (linear bounded) operator from $E$ into $c_0$ is weakly compact. It is proved that, for an integer $k>1$, every $k$-homogeneous polynomial from $E$ into $c_0$ is weakly compact if and only if the space ${\cal P}(^kE)$ of scalar valued polynomials on $E$ is reflexive. This is equivalent to the symmetric $k$-fold projective tensor product of $E$ (i.e., the predual of ${\cal P}(^kE)$) having the Grothendieck property. The Grothendieck property of the projective tensor product $E\widehat{\bigotimes}F$ is also characterized. Moreover, the Grothendieck property of $E$ is described in terms of sequences of polynomials. Finally, it is shown that if every operator from $E$ into $c_0$ is completely continuous, then so is every polynomial between these spaces.
Unconditionally converging polynomials on Banach spaces
Manuel Gonzalez,Joaquin M. Gutierrez
Mathematics , 1994, DOI: 10.1017/S030500410007314X
Abstract: We prove that weakly unconditionally Cauchy (w.u.C.) series and unconditionally converging (u.c.) series are preserved under the action of polynomials or holomorphic functions on Banach spaces, with natural restrictions in the latter case. Thus it is natural to introduce the unconditionally converging polynomials, defined as polynomials taking w.u.C. series into u.c.\ series, and analogously, the unconditionally converging holomorphic functions. We show that most of the classes of polynomials which have been considered in the literature consist of unconditionally converging polynomials. Then we study several ``polynomial properties'' of Banach spaces, defined in terms of relations of inclusion between classes of polynomials, and also some ``holomorphic properties''. We find remarkable differences with the corresponding ``linear properties''. For example, we show that a Banach space $E$ has the polynomial property (V) if and only if the spaces of homogeneous scalar polynomials ${\cal P}(^k\!E)$, $k\in{\bf N}$, or the space of scalar holomorphic mappings of bounded type ${\cal H}_b(E),$ are reflexive. In this case the dual space $E^*$, like the dual of Tsirelson's space, is reflexive and contains no copies of $\ell_p$.
Factorization of weakly continuous holomorphic mappings
Manuel Gonzalez,Joaquin M. Gutierrez
Mathematics , 1996,
Abstract: We prove a basic property of continuous multilinear mappings between topological vector spaces, from which we derive an easy proof of the fact that a multilinear mapping (and a polynomial) between topological vector spaces is weakly continuous on weakly bounded sets if and only if it is weakly {\it uniformly\/} continuous on weakly bounded sets. This result was obtained in 1983 by Aron, Herv\'es and Valdivia for polynomials between Banach spaces, and it also holds if the weak topology is replaced by a coarser one. However, we show that it need not be true for a stronger topology, thus answering a question raised by Aron. As an application of the first result, we prove that a holomorphic mapping $f$ between complex Banach spaces is weakly uniformly continuous on bounded subsets if and only if it admits a factorization of the form $f=g\circ S$, where $S$ is a compact operator and $g$ a holomorphic mapping.
Factores inmunológicos y microbiológicos asociados con la etiología de la estomatitis aftosa recurrente
Correnti,M; Gutierrez,R; Perrone,M;
Acta Odontológica Venezolana , 2008,
Abstract: recurrent aphtous stomatitis (ras) is a common, painful and ulcerative disorder of the oral cavity of unknown etiology. several reports have suggested that the patients affected with this condition have a defectous celular immune response. aditionally, adhesion molecules are known to play a crucial role in the recruitment of immflamatory cells to sites of inflammation. adhesion molecules vcam-1 (vascular cell adhesion molecule-1), and icam-1 (intercellular adhesion molecule-1) are essential for the binding of inflammatory cells to endothelial cells. circulating forms of these molecules have been detected in a number of vasculitic disease. ras has some features of a vasculitic disease process. helicobacter pylori has been shown to be the causative factor in peptic ulcers, which is very similar with ras the aim of this study was to review the inmmunological and microbiological factors associated with the etiology of ras.
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