نتایج جستجو برای: functional projections

تعداد نتایج: 633472  

1998
G. P. Nason

This article describes the adaption of exploratory projection pursuit for use with functional data. The aim is to nd \interesting" projections of functional data: e.g. to separate curves into meaningful clusters. Functional data are projected onto low-dimensional subspaces determined by a projection function using a suitable inner product. Such a projection is rapidly computed by representing d...

Journal: :Multiscale Modeling & Simulation 2011
Robert Scheichl Panayot S. Vassilevski Ludmil Zikatanov

This paper is on the construction of energy minimizing coarse spaces that obey certain functional constraints and can thus be used for example to build robust coarse spaces for elliptic problems with large variations in the coefficients. In practice they are built by patching together solutions to appropriate local saddle point or eigenvalue problems. We develop an abstract framework for such c...

2014
Markus Rothermel Matt Wachowiak

Processing of sensory information is substantially shaped by centrifugal, or feedback, projections from higher cortical areas, yet the functional properties of these projections are poorly characterized. Here, we used genetically-encoded calcium sensors (GCaMPs) to functionally image activation of centrifugal projections targeting the olfactory bulb (OB). The OB receives massive centrifugal inp...

Journal: :The Journal of neuroscience : the official journal of the Society for Neuroscience 2014
Sepideh Keshavarzi Robert K P Sullivan Damian J Ianno Pankaj Sah

The medial nucleus of the amygdala (MeA) plays a key role in innate emotional behaviors by relaying olfactory information to hypothalamic nuclei involved in reproduction and defense. However, little is known about the neuronal components of this region or their role in the olfactory-processing circuitry of the amygdala. Here, we have characterized neurons in the posteroventral division of the m...

Journal: :J. Multivariate Analysis 2014
Stefan Fremdt Lajos Horváth Piotr Kokoszka Josef G. Steinebach

Functional principal components (FPC’s) provide the most important and most extensively used tool for dimension reduction and inference for functional data. The selection of the number, d, of the FPC’s to be used in a specific procedure has attracted a fair amount of attention, and a number of reasonably effective approaches exist. Intuitively, they assume that the functional data can be suffic...

Journal: :iranian journal of medical physics 0
shahla ahmadi m.sc. in nuclear engineering, faculty of engineering, science and research branch, islamic azad university, tehran, iran hossein rajabi associate professor, medical physics dept., faculty of medicine, tarbiat modares university, tehran, iran farshid babapoor assistant professor, nuclear engineering dept., faculty of engineering, science and research branch, islamic azad university, tehran, iran faraz kalantari ph.d. student, medical physics dept., faculty of medicine, tarbiat modares university, research institute for nuclear medicine, tehran university of medical sciences,tehran, iran

introduction: the main goal of spect imaging is to determine activity distribution inside the organs of the body. however, due to photon attenuation, it is almost impossible to do a quantitative study. in this paper, we suggest a mathematical relationship between activity distribution and its corresponding projections using a transfer matrix. monte carlo simulation was used to find a precise tr...

Journal: :The European Journal of Neuroscience 2007
Roberta Calzavara Philippe Mailly Suzanne N Haber

Our previous data indicate that there are specific features of the corticostriatal pathways from the prefrontal cortex. First, corticostriatal pathways are composed of focal, circumscribed projections and of diffuse, widespread projections. Second, there is some convergence between terminal fields from different functional regions of the prefrontal cortex. Third, anterior cingulate projections ...

Journal: :Neuron 2012
Foivos Markopoulos Dan Rokni David H. Gire Venkatesh N. Murthy

Sensory perception is not a simple feed-forward process, and higher brain areas can actively modulate information processing in "lower" areas. We used optogenetic methods to examine how cortical feedback projections affect circuits in the first olfactory processing stage, the olfactory bulb. Selective activation of back projections from the anterior olfactory nucleus/cortex (AON) revealed funct...

1982
Erol Gelenbe Danièle Gardy

In this paper we consider tabulated data or relations in a data base __I__-_ system which are constrained by functional dependencies. This implies that the data in certain columns of each table is determined by the data contained in some other columns. The problem we address is that of the computation of the size of projections of the data on a subset of the columns. This may be viewed as the p...

Journal: :iranian journal of nuclear medicine 2011
faraz kalantari hossein rajabi mohsen saghari alireza emami ardekani

introduction: monte carlo (mc) is the most common method for simulating virtual spect projections. it is useful for optimizing procedures, evaluating correction algorithms and more recently image reconstruction as a forward projector in iterative algorithms; however, the main drawback of mc is its long run time. we introduced a model based method considering the effect of body attenuation and i...

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