Search results for "principal"

Dimensionality Reduction via Regression in Hyperspectral Imagery

2015

This paper introduces a new unsupervised method for dimensionality reduction via regression (DRR). The algorithm belongs to the family of invertible transforms that generalize Principal Component Analysis (PCA) by using curvilinear instead of linear features. DRR identifies the nonlinear features through multivariate regression to ensure the reduction in redundancy between he PCA coefficients, the reduction of the variance of the scores, and the reduction in the reconstruction error. More importantly, unlike other nonlinear dimensionality reduction methods, the invertibility, volume-preservation, and straightforward out-of-sample extension, makes DRR interpretable and easy to apply. The pro…

Fast PET Scan Tumor Segmentation Using Superpixels, Principal Component Analysis and K-Means Clustering

2018

Positron Emission Tomography scan images are extensively used in radiotherapy planning, clinical diagnosis, assessment of growth and treatment of a tumor. These all rely on fidelity and speed of detection and delineation algorithm. Despite intensive research, segmentation remained a challenging problem due to the diverse image content, resolution, shape, and noise. This paper presents a fast positron emission tomography tumor segmentation method in which superpixels are extracted first from the input image. Principal component analysis is then applied on the superpixels and also on their average. Distance vector of each superpixel from the average is computed in principal components coordin…

Spontaneous emission of a sodium Rydberg atom close to an optical nanofibre

2019

International audience; We report on numerical calculations of the spontaneous emission rate of a Rydberg-excited sodium atom in the vicinity of an optical nanobre. In particular, we study how this rate varies with the distance of the atom to the bre, the bre's radius, the symmetry s or p of the Rydberg state as well as its principal quantum number. We nd that a fraction of the spontaneously emitted light can be captured and guided along the bre. This suggests that such a setup could be used for networking atomic ensembles, manipulated in a collective way due to the Rydberg blockade phenomenon.

STATISTICAL METHODS FOR THE DISCRIMINATION OF FOUR FORMS OF DIPLEGIA

Design of a virtual instrument for water quality monitoring across the Internet

2001

Abstract This article presents the design of a new distributed and multi-platform system for water quality monitoring, enhanced with powerful Internet capabilities. The measured variables are temperature, turbidity, pH, dissolved oxygen, and electrical conductivity. The signal-conditioning block has been simplified through the use of software routines for thermal compensation, hence, reducing the cost and dimensions. The system offers a wide variety of Internet capabilities, like e-mail alarm notifications, automatic storage of measured data in a remote machine via the FTP protocol, dynamic generation of HTML reports, real time graphs, and indicators visible from a remote web browser, etc. …

Revamping Research on Unrelated Diversification Strategy: Perspectives, Opportunities and Challenges for Future Inquiry

2015

With the aim of achieving an advanced understanding of current research on unrelated diversification and providing fruitful groundwork to foster active interchange between disciplinary traditions, this paper detects articles from two relevant research streams; i.e., strategic management and financial economics. We first provide a brief overview of management thinking on unrelated diversification strategy. Then, we present a conceptual map that offers a comprehensive appreciation of unrelated diversification strategy antecedents (i.e., environmental and institutional, organizational value-enhancing, and managerial drivers), implementation process (i.e., managerial complexity, misallocation o…

Beyond the Law and Finance Approach: The Shareholders' Cognitive Role and Its Effects on the Analysis of Ownership Structure and Corporate Governance

2004

The dominant law and finance approach of ownership structure and corporate governance is based on an unrealistic assumption, that of a total complete separation between ownership and control, in particular in the European nations. This approach based on the seminal Berle and Means' analysis and on agency theory, postulates that shareholders carry only a financial function limited to equity financing and assumption of financial risk. In view of the actual ownership structures, this approach has a weak explanatory power. Therefore, this article proposes another model, based on the cognitive role - directing and contribution of competences -, that the main shareholders often keep. It is possib…

Forecasting Financial Crises and Contagion in Asia Using Dynamic Factor Analysis

2009

In this paper we use principal components analysis to obtain vulnerability indicators able to predict financial turmoil. Probit modelling through principal components and also stochastic simulation of a Dynamic Factor model are used to produce the corresponding probability forecasts regarding the currency crisis events affecting a number of East Asian countries during the 1997-1998 period. The principal components model improves upon a number of competing models, in terms of out-of-sample forecasting performance.

Public-Private Partnerships: Agency Costs in the Privatization of Social Infrastructure Financing

2019

Public-private partnerships (PPPs) have been subjected to considerable public debate. In particular, this debate has concerned PPP financing and its implications. Using insights from agency theory, this study aims to develop a theoretical understanding of PPP financing. The following research question is investigated: How does the privatization of financing decrease or increase agency costs in social infrastructure PPPs? A comparative case study consisting of four Norwegian PPP projects with different financial configurations is undertaken. The findings suggest that the private sector is risk averse, increasing the cost of capital. In addition, private financing does not seem to have the i…

The Impact of Corporate Governance on Internet Financial Reporting in Concentrated Ownership Companies

2013

In the context of agency theory this study investigates the effect of corporate governance (CG) on Internet Fianncial Reporting disclosure (IFR) in concentrated ownership envitonment, such as Italy. We hypothesize that IFR may be explain in term of increasing trasparency in order to defen minority shareholder interest, so we predict, and find, a positive association between the extent of a firm's IFR and its CG and a negative assocaition between IFR and ownership structure. Abstract. This study investigates, upon agency theory, the effect of corporate governance (CG) on Internet Financial Reporting disclosure (IFR) in an ownership concentrated environment, such as Ita-ly. We hypothesize tha…