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Rigorous Definition (rigorous + definition)

Distribution by Scientific Domains
Business, Economics, Finance and Accounting28%

Selected Abstracts

Enhancing Bounding Volumes using Support Plane Mappings for Collision Detection

COMPUTER GRAPHICS FORUM, Issue 5 2010
Athanasios Vogiannou
Abstract In this paper we present a new method for improving the performance of the widely used Bounding Volume Hierarchies for collision detection. The major contribution of our work is a culling algorithm that serves as a generalization of the Separating Axis Theorem for non parallel axes, based on the well-known concept of support planes. We also provide a rigorous definition of support plane mappings and implementation details regarding the application of the proposed method to commonly used bounding volumes. The paper describes the theoretical foundation and an overall evaluation of the proposed algorithm. It demonstrates its high culling efficiency and in its application, significant improvement of timing performance with different types of bounding volumes and support plane mappings for rigid body simulations. [source]

Where is Independent Director Efficacy?

CORPORATE GOVERNANCE, Issue 4 2007
Chin-Jung Luan
Theoretically and empirically, the linkage between outside directors and firm performance is not conclusive in previous studies. We suspect that the mixed results are due to the failure to meet the requirements of the independence of outside directors. As the Taiwanese government has a rigorous definition of outside director independence, we employ a data set from Taiwan to test the impact of independent outside director assignment on a firm's performance. Our findings suggest that after controlling for a firm's past performance, independent outside director appointments do have a significantly positive impact on a firm's performance, and outperforming firms may have better performance but not significantly when assigning outside directors due to their absorptive capacity. [source]

A fresh look at dry weight

HEMODIALYSIS INTERNATIONAL, Issue 4 2008
Jochen RAIMANN
Abstract The concept of dry weight (DW) is central to dialysis therapy. The most commonly used definition of DW is the weight below which patients become hypotensive on dialysis. However, this definition is dependent on patient symptoms. A more rigorous definition of DW is the body weight at a physiological extracellular volume (ECV) state. Overhydration is an excess in ECV above that found in healthy subjects. In healthy subjects, within extremes of salt intake, ECV may vary between 280 and 340 mL/kg lean body mass. Sodium accumulation is one of the many consequences of renal failure; it results in increased water intake and an increase in ECV, and an accompanying rise in blood pressure with its clinical sequelae, most prominently cardiovascular and cerebrovascular diseases. Recently characterized endogenous digitalis-like factors which are released in response to ECV expansion have extended this traditional picture. Efforts to reduce a positive sodium balance include dietary counseling and avoidance of iatrogenic intradialytic sodium loading, such as dialysate sodium exceeding serum levels, sodium profiling, and intravenous saline. Excess ECV is predominantly located in the interstitial compartment and must be removed during dialysis therapy by ultrafiltration. During this process, interstitial fluid redistributes to the intravascular space via uptake in the capillary bed. In addition to that mechanism, we propose that increased lymphatic flow into the venous system contributes to plasma refilling. Both clinical and technical means are used to assess the presence of DW. Continuous segmental calf bioimpedance is a promising new technology for intradialytic DW diagnosis. [source]

The Impact of False Rejection Risk on Posterior Audit Risk Measurement

INTERNATIONAL JOURNAL OF AUDITING, Issue 1 2001
Anne D. Woodhead
This paper investigates false rejection risk, analysing the a priori relationship between the risk of false rejection and the more common risk of false acceptance, of an account balance by a substantive test. The paper uses probability theory to specify the relationship between these two risks and thus generate a model of posterior audit risk. The paper proceeds to investigate the relationship using the power function of basic statistics. This specifies the relationship between (i) the probability of rejecting the account balance and (ii) the size of the error which the balance contains. We argue that unless there is a discontinuity in the power function around the specified value of material error, then posterior audit risk will be unaffected by the substantive tests undertaken. Posterior risk will then be determined entirely by the assessed inherent and control risks. This conclusion is counter-intuitive to the approach to audit risk adopted by many professional pronouncements and results from the adoption of a mathematically rigorous definition of the risks encountered by the auditor. The primary conclusion is that the discontinuity arises under conditions of careful audit planning. If planning is careful, then false rejection risk contributes very little to posterior risk. In addition, there is very little difference between planned risk and posterior risk. [source]

Security and delay issues in SIP systems

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2009
Christian Callegari
Abstract The deployment of multimedia over IP (MoIP), and in particular voice over IP services, requires to solve new security issues they introduce, before completely exploiting the great opportunities they offer to telecommunication market. Furthermore, the implementation of various security measures can cause a marked deterioration in quality of service, which is fundamental to the operation of an MoIP network that meets users' quality expectations. In particular, because of the time-critical nature of MoIP and its low tolerance for disruption and packet loss, many security measures implemented in traditional data networks are simply not applicable in their current form. This paper presents an analysis of the security options of Session Initiation Protocol- (SIP)-based MoIP architecture aimed at evaluating their impact on delay. In particular, each security option is analyzed in terms of clock cycles needed to perform the related operations. This parameter could be used to estimate the delay introduced by the security mechanisms. Moreover the paper proposes a rigorous definition of five security profiles, which provide different levels of security to a MoIP system. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Changing the economic landscape: The phenomenon of regional inversion in the US manufacturing sector,

PAPERS IN REGIONAL SCIENCE, Issue 4 2002
Luis Fernando Lanaspa-Santolaria
Regional Inversion; US manufacturing sector; unit root tests; structural breaks Abstract Regional inversion is the name given to the phenomenon whereby the traditional industrial areas of certain countries lose their weight in favor of what were formerly peripheral zones. Against this background our first objective is to offer a formal and rigorous definition of the concept of regional inversion from an econometric standpoint. To that end we relate such a process with the long-run concepts of convergence and catching-up. Secondly, we test this definition through the use of unit root statistics and apply these to demonstrate the presence of this phenomenon in some of the US two-digit SIC industries. [source]

The "Ductilities" in Single Phase Steels from Usual to Nanoscale Microstructures

ADVANCED ENGINEERING MATERIALS, Issue 10 2009
Olivier Bouaziz
Abstract The control and the improvement of the ductility of nanostructured structural steels is one of the key challenges in assessing the technological viability of this metallurgical strategy. In the present paper, it is shown that more rigorous definitions of the ductility are required in order to avoid possible confusions. After this preliminary work, a more transparent analysis is done concerning the effect of the microstructural scale showing clearly the weaknesses and the strengths of ultra-fine single phase steels. Finally, possible ways to overcome the main limitations are presented. [source]