Search results for "Spatial"
showing 10 items of 2121 documents
Multi-subject fMRI analysis via combined independent component analysis and shift-invariant canonical polyadic decomposition
2014
Canonical polyadic decomposition (CPD) may face a local optimal problem when analyzing multi-subject fMRI data with inter-subject variability. Beckmann and Smith proposed a tensor PICA approach that incorporated an independence constraint to the spatial modality by combining CPD with ICA, and alleviated the problem of inter-subject spatial map (SM) variability.This study extends tensor PICA to incorporate additional inter-subject time course (TC) variability and to connect CPD and ICA in a new way. Assuming multiple subjects share common TCs but with different time delays, we accommodate subject-dependent TC delays into the CP model based on the idea of shift-invariant CP (SCP). We use ICA …
MODIS-Based Monthly LST Products over Amazonia under Different Cloud Mask Schemes
2016
One of the major problems in the monitoring of tropical rainforests using satellite imagery is their persistent cloud coverage. The use of daily observations derived from high temporal resolution sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), could potentially help to mitigate this issue, increasing the number of clear-sky observations. However, the cloud contamination effect should be removed from these results in order to provide a reliable description of these forests. In this study the available MODIS Land Surface Temperature (LST) products have been reprocessed over the Amazon Basin (10 N–20 S, 80 W–45 W) by introducing different cloud masking schemes. The mont…
A Two-layer Partitioning for Non-point Spatial Data
2021
Non-point spatial objects (e.g., polygons, linestrings, etc.) are ubiquitous and their effective management is always timely. We study the problem of indexing non-point objects in memory. We propose a secondary partitioning technique for space-oriented partitioning indices (e.g., grids), which improves their performance significantly, by avoiding the generation and elimination of duplicate results. Our approach is novel and of a high impact, as (i) it is extremely easy to implement and (ii) it can be used by any space-partitioning index. We show how our approach can be used to boost the performance of spatial range queries. We also show how we can avoid performing the expensive refinement s…
Contextual Metadata for Document Databases
2005
Metadata has always been an important means to support accessibility of information in document collections. Metadata can be, for example, bibliographic data manually created for each document at the time of document storage. The indexes created by Web search engines serve as metadata about the content of Web documents. In the semantic Web solutions, ontologies are used to store semantic metadata (Berners-Lee et al., 2001). Attaching a common ontology to a set of heterogeneous document databases may be used to support data integration. Creation of the common ontology requires profound understanding of the concepts used in the databases. It is a demanding task, especially in cases where the …
Novel Indexing Method of Relations Between Salient Objects
2011
Since the last decade, images have been integrated into several application domains such as GIS, medicine, etc. This integration necessitates new managing methods particularly in image retrieval. Queries should be formulated using different types of features such as low-level features of images (histograms, color distribution, etc.), spatial and temporal relations between salient objects, semantic features, etc. In this chapter, we propose a novel method for identifying and indexing several types of relations between salient objects. Spatial relations are used here to show how our method can provide high expressive power to relations in comparison to the traditional methods.
A Framework to Assess the Information Dynamics of Source EEG Activity and Its Application to Epileptic Brain Networks
2020
This study introduces a framework for the information-theoretic analysis of brain functional connectivity performed at the level of electroencephalogram (EEG) sources. The framework combines the use of common spatial patterns to select the EEG components which maximize the variance between two experimental conditions, simultaneous implementation of vector autoregressive modeling (VAR) with independent component analysis to describe the joint source dynamics and their projection to the scalp, and computation of information dynamics measures (information storage, information transfer, statistically significant network links) from the source VAR parameters. The proposed framework was tested on…
Tactile field and the dual nature of touch: Poster
2021
I investigate whether it is justified to postulate tactile field analogous in its properties to visual field. I argue that the answer is both ‘yes’ and ‘no’ due to the dual nature of touch: touch is both an interoceptive modality which presents states of one’s body and an exteroceptive modality which presents external entities. More specifically, the interoceptive tactile space, in which tactile bodily sensations are experienced to be localized, has a character of a spatial field. On the other hand, the exteroceptive tactile space, in which external, tactile objects are experienced to be localized does not have field-status.
Atmospheric correction of ENVISAT/MERIS data over inland waters: Validation for European lakes
2010
Traditional methods for aerosol retrieval and atmospheric correction of remote sensing data over water surfaces are based on the assumption of zero water reflectance in the near-infrared. Another type of approach which is becoming very popular in atmospheric correction over water is based on the simultaneous retrieval of atmospheric and water parameters through the inversion of coupled atmospheric and bio-optical water models. Both types of approaches may lead to substantial errors over optically-complex water bodies, such as case II waters, in which a wide range of temporal and spatial variations in the concentration of water constituents is expected. This causes the water reflectance in t…
Telpas semantika Teodora Fontānes romānā „Efija Brīsta”
2020
Telpa – viena no svarīgākajām kategorijām cilvēka pasaules uztverē. Ikdienišķā telpas definīcija nav problemātiska, atšķirībā no tās teorētiskās eksplikācijas jeb paskaidrojuma. Līdz par 20. gadsimtam telpas definīcija nebija pietiekami izpētīta, tomēr ar telpiskā pagrieziena (Spatial Turn) sākumu situācija ir mainījusies – telpa kļuva par kultūras vērtību, kas vēlāk ļāva paplašināt tās pētījuma horizontus. Pēdējo gadsimtu gaitā telpas izpētei tika veltīti daudzi darbi, kas pierāda tās aktualitāti līdz pat šodienai. Šis maģistra darbs nodarbojas ar literārās telpas semantiku jeb tās nozīmi un izpratni vācu rakstnieka Teodora Fontānes romānā Efija Brīsta. Šis romāns ir raksturīgs piemērs, ku…
Lack of APP and APLP2 in GABAergic Forebrain Neurons Impairs Synaptic Plasticity and Cognition.
2020
AbstractAmyloid-β precursor protein (APP) is central to the pathogenesis of Alzheimer’s disease, yet its physiological functions remain incompletely understood. Previous studies had indicated important synaptic functions of APP and the closely related homologue APLP2 in excitatory forebrain neurons for spine density, synaptic plasticity, and behavior. Here, we show that APP is also widely expressed in several interneuron subtypes, both in hippocampus and cortex. To address the functional role of APP in inhibitory neurons, we generated mice with a conditional APP/APLP2 double knockout (cDKO) in GABAergic forebrain neurons using DlxCre mice. These DlxCre cDKO mice exhibit cognitive deficits i…