168 resultados para FOURIER SPECTRUM
Resumo:
We report a male child born with complete absence of his external ear, hemifacial microsomia of the right side, high arched palate, a down-turned upper lip and slightly upslanting palpebral fissures. The features were suggestive of facio-auriculo-vertebral spectrum. Investigations showed a tandem duplication of the short arm of one chromosome 10 with apparent breakpoints at p14 and p15. This case extends the list of chromosomal abnormalities associated with the facio-auriculo-vertebral phenotype and also adds useful clinical information to possible trisomy 10p phenotypes.
Resumo:
Let $G$ be a locally compact $\sigma$-compact group. Motivated by an earlier notion for discrete groups due to Effros and Ruan, we introduce the multidimensional Fourier algebra $A^n(G)$ of $G$. We characterise the completely bounded multidimensional multipliers associated with $A^n(G)$ in several equivalent ways. In particular, we establish a completely isometric embedding of the space of all $n$-dimensional completely bounded multipliers into the space of all Schur multipliers on $G^{n+1}$ with respect to the (left) Haar measure. We show that in the case $G$ is amenable the space of completely bounded multidimensional multipliers coincides with the multidimensional Fourier-Stieltjes algebra of $G$ introduced by Ylinen. We extend some well-known results for abelian groups to the multidimensional setting.
Resumo:
A bounded linear operator $T$ on a Banach space $X$ is called frequently hypercyclic if there exists $x\in X$ such that the lower density of the set $\{n\in\N:T^nx\in U\}$ is positive for any non-empty open subset $U$ of $X$. Bayart and Grivaux have raised a question whether there is a frequently hypercyclic operator on any separable infinite dimensional Banach space. We prove that the spectrum of a frequently hypercyclic operator has no isolated points. It follows that there are no frequently hypercyclic operators on all complex and on some real hereditarily indecomposable Banach spaces, which provides a negative answer to the above question.
Resumo:
As architects and designers we have a responsibility to provide an inclusive built environment. For the Autistic Spectrum Disorder (ASD) sufferer however, the built environment can be a frightening and confusing place, difficult to negotiate and tolerate. The challenge of integrating more fully into society is denied by an alienating built environment. This barrier can be magnified for ASD pupils in a poorly designed school, where their environment can further distance them from learning. Instead, if more at ease in their surroundings, in an ASD friendly environment, the ASD pupil stands a greater chance of doing better.
Whilst researchers have looked at the classroomenvironment, the transition of classroom to corridor andbeyond has so far been largely ignored. However, theneed for a well-considered threshold between class andcorridor needs to be considered. In this regard, threshold is much more than a doorway, but instead an event that demands a carefully considered place. The following paper firstly outlines why threshold as place andevent for the ASD pupil should be given consideration. It then goes onto highlight, through case studies in anIrish context, the opportunities for aiding the ASD pupil integrating in a mainstream school environment throughsensitive use of threshold. Finally it highlights inconclusion, some of the benefits for an enriched school environment for all pupils, if considering threshold as design generator.The objective is straightforward. By increasing awareness of the relationship between the ASD child and the built environment it will hopefully facilitate greater inclusion of the ASD pupil into mainstream education and society at large.
Resumo:
The imaging properties of a phase conjugating lens operating in the far field zone of the imaged source and augmented with scatterers positioned in the source near field region are theoretically studied in this paper. The phase conjugating lens consists of a double sided 2D assembly of straight wire elements, individually interconnected through phase conjugation operators. The scattering elements are straight wire segments which are loaded with lumped impedance loads at their centers. We analytically and numerically analyze all stages of the imaging process; i) evanescent-to-propagating spectrum conversion; ii) focusing properties of infinite or finite sized phase conjugating lens; iii) source reconstruction upon propagating-to-evanescent spectrum conversion. We show that the resolution that can be achieved depends critically on the separation distance between the imaged source and scattering arrangement, as well as on the topology of the scatterers used. Imaged focal widths of up to one-seventh wavelength are demonstrated. The results obtained indicate the possibility of such an arrangement as a potential practical means for realising using conventional materials devices for fine feature extraction by electromagnetic lensing at distances remotely located from the source objects under investigation
Resumo:
In this paper, the distribution of the ratio of extreme eigenvalues of a complex Wishart matrix is studied in order to calculate the exact decision threshold as a function of the desired probability of false alarm for the maximum-minimum eigenvalue (MME) detector. In contrast to the asymptotic analysis reported in the literature, we consider a finite number of cooperative receivers and a finite number of samples and derive the exact decision threshold for the probability of false alarm. The proposed exact formulation is further reduced to the case of two receiver-based cooperative spectrum sensing. In addition, an approximate closed-form formula of the exact threshold is derived in terms of a desired probability of false alarm for a special case having equal number of receive antennas and signal samples. Finally, the derived analytical exact decision thresholds are verified with Monte-Carlo simulations. We show that the probability of detection performance using the proposed exact decision thresholds achieves significant performance gains compared to the performance of the asymptotic decision threshold.
Resumo:
We present extensive spectroscopic time series observations of the multiperiodic, rapidly rotating, delta Scuti star tau Pegasi. Information about the oscillations is contained within the patterns of line-profile variation of the star's blended absorption-line spectrum. We introduce the new technique of Doppler deconvolution with which to extract these patterns by modeling the intrinsic stellar spectrum and the broadening functions for each spectrum in the time series. Frequencies and modes of oscillation are identified from the variations using the technique of Fourier-Doppler imaging and a two-dimensional least-squares cleaning algorithm. We find a rich mode spectrum with degrees up to l = 20 and with frequencies below about 35 cycles day-1. Those modes with the largest amplitudes have frequencies that lie within a narrow band. We conclude that the observed spectrum can be explained if the modes of tau Peg propagate in the prograde direction with l ~= |m| and with frequencies that are about equal in the corotating frame of the star. We discuss the implications of these results for the prospect of delta Scuti seismology.
Resumo:
This study used the Movement Assessment Battery for Children (M-ABC2) to assess the level of motor skill in children aged 7-10 years with autism (n=18) and compared their performance to two groups of age-matched typically developing children; a receptive vocabulary matched group (n=19) and a nonverbal IQ matched group (n=22). Although the results support previous work, as indicated by a significant general motor impairment in the group with autism, a sub-analysis of the M-ABC2 revealed that there were only 2 out of 8 subcomponent skills which showed universally significant specific deficits for the autism group; namely catching a ball and static balance. These results suggest that motor skill deficits associated with autism may not be pervasive but more apparent in activities demanding complex, interceptive actions or core balance ability.