Search results for "Spatial"

SIFT Matching by Context Exposed

2023

This paper investigates how to step up local image descriptor matching by exploiting matching context information. Two main contexts are identified, originated respectively from the descriptor space and from the keypoint space. The former is generally used to design the actual matching strategy while the latter to filter matches according to the local spatial consistency. On this basis, a new matching strategy and a novel local spatial filter, named respectively blob matching and Delaunay Triangulation Matching (DTM) are devised. Blob matching provides a general matching framework by merging together several strategies, including rank-based pre-filtering as well as many-to-many and symmetri…

Diffusion map for clustering fMRI spatial maps extracted by Indipendent Component Analysis

2013

Functional magnetic resonance imaging (fMRI) produces data about activity inside the brain, from which spatial maps can be extracted by independent component analysis (ICA). In datasets, there are n spatial maps that contain p voxels. The number of voxels is very high compared to the number of analyzed spatial maps. Clustering of the spatial maps is usually based on correlation matrices. This usually works well, although such a similarity matrix inherently can explain only a certain amount of the total variance contained in the high-dimensional data where n is relatively small but p is large. For high-dimensional space, it is reasonable to perform dimensionality reduction before clustering.…

The network of global corporate control.

2011

The structure of the control network of transnational corporations affects global market competition and financial stability. So far, only small national samples were studied and there was no appropriate methodology to assess control globally. We present the first investigation of the architecture of the international ownership network, along with the computation of the control held by each global player. We find that transnational corporations form a giant bow-tie structure and that a large portion of control flows to a small tightly-knit core of financial institutions. This core can be seen as an economic “super-entity” that raises new important issues both for researchers and policy make…

Classical automata on promise problems

2015

Promise problems were mainly studied in quantum automata theory. Here we focus on state complexity of classical automata for promise problems. First, it was known that there is a family of unary promise problems solvable by quantum automata by using a single qubit, but the number of states required by corresponding one-way deterministic automata cannot be bounded by a constant. For this family, we show that even two-way nondeterminism does not help to save a single state. By comparing this with the corresponding state complexity of alternating machines, we then get a tight exponential gap between two-way nondeterministic and one-way alternating automata solving unary promise problems. Secon…

Depth-Adapted CNN for RGB-D cameras

2020

Conventional 2D Convolutional Neural Networks (CNN) extract features from an input image by applying linear filters. These filters compute the spatial coherence by weighting the photometric information on a fixed neighborhood without taking into account the geometric information. We tackle the problem of improving the classical RGB CNN methods by using the depth information provided by the RGB-D cameras. State-of-the-art approaches use depth as an additional channel or image (HHA) or pass from 2D CNN to 3D CNN. This paper proposes a novel and generic procedure to articulate both photometric and geometric information in CNN architecture. The depth data is represented as a 2D offset to adapt …

Bayesian Analysis of Population Health Data

2021

The analysis of population-wide datasets can provide insight on the health status of large populations so that public health officials can make data-driven decisions. The analysis of such datasets often requires highly parameterized models with different types of fixed and random effects to account for risk factors, spatial and temporal variations, multilevel effects and other sources on uncertainty. To illustrate the potential of Bayesian hierarchical models, a dataset of about 500,000 inhabitants released by the Polish National Health Fund containing information about ischemic stroke incidence for a 2-year period is analyzed using different types of models. Spatial logistic regression and…

2015

Recent evidence suggests a rather gradual developmental trajectory for processing vertical relational face information, lasting well into late adolescence (de Heering and Schlitz, 2012). Results from another recent study (Tanaka et al., 2014) indicate that children and young adolescents use a smaller spatial integration field for faces than do adults, which particularly affects assessment of long-range vertical relations. Here we studied sensitivity to replacement of eyes and eyebrows (F), variation of inter-eye distance (H) and eye height (V) in young adolescents (11-12 years), young (21-25 years) and middle-age adults (51-62 years). In order to provide a baseline for potential age effects…

The interrelation between socio-spatial and institutional context and family business characteristics

2019

Tomaselli, Agrò, Fazio e Fricano show how family firms draw strength from the regional institutional context (where the region is properly intended as an administrative sub-unit at national level), as well as contribute to its evolution via their own actions. The variation in family competencies and internal dynamics lead to differences in family firms's overlla performance. The relationship with the regional institutional system in mutually sinergic - even marginal family businesses add their voice to whole, resulting in grater collective political influence, and at the same time the institutions at the regional level provide some degree of legitimacy to all players.

‘Can I tell?’ : Children’s participation and positioning in a secretive atmosphere in family therapy

2020

As a multifaceted phenomenon, family secrets affect interaction in the therapeutic system. This qualitative study, applying the multi‐actor Dialogical Methods for Investigations of Happening of Change, explored how children participated and positioned themselves in family therapy in a climate of family secrets. The results showed that the children were active co‐participants in the complex dynamics of a secretive atmosphere, involving themselves in the paradoxical processes of reconstructing and deconstructing the secretive and unsafe climate. In family therapy, a child’s symptomatic behaviour can function as a visible ‘cover story’ for invisible constructions of secrets, preventing sensiti…

Selecting the Kth nearest-neighbour for clutter removal in spatial point processes through segmented regression models

2023

We consider the problem of feature detection, in the presence of clutter in spatial point processes. A previous study addresses the issue of the selection of the best nearest neighbour for clutter removal. We outline a simple workflow to automatically estimate the number of nearest neighbours by means of segmented regression models applied to an entropy measure of cluster separation. The method is suitable for a feature with clutter as two superimposed Poisson processes on any twodimensional space, including linear networks. We present simulations to illustrate the method and an application to the problem of seismic fault detection.