Search results for "LIMIT"

More limit cycles than expected in Liénard equations

2007

The paper deals with classical polynomial Lienard equations, i.e. planar vector fields associated to scalar second order differential equations x"+ f(x)x' + x = 0 where f is a polynomial. We prove that for a well-chosen polynomial f of degree 6, the equation exhibits 4 limit cycles. It induces that for n ≥ 3 there exist polynomials f of degree 2n such that the related equations exhibit more than n limit cycles. This contradicts the conjecture of Lins, de Melo and Pugh stating that for Lienard equations as above, with f of degree 2n, the maximum number of limit cycles is n. The limit cycles that we found are relaxation oscillations which appear in slow-fast systems at the boundary of classic…

Fate of aerobic granular sludge in the long-term: The role of EPSs on the clogging of granular sludge porosity

2016

This work aims to investigate the stability of aerobic granular sludge in the long term, focusing on the clogging of the granular sludge porosity exerted by the extracellular polymeric substances (EPSs). The effects of different cycle lengths (short and long-term cycle) on the granular sludge stability were investigated. Results obtained outlined that during the short duration cycle, the formation and breakage of the aerobic granules were continuously observed. During this period, the excess of EPS production contributed to the clogging of the granules porosity, causing their breakage in the long run. During the long-duration cycle, the extended famine period entailed a greater EPSs consump…

Mapping Posidonia oceanica lower limit combining high resolution instruments (SSS and MBS)

2014

High Wage Workers Match with High Wage Firms: Clear Evidence of the Effects of Limited Mobility Bias

2012

Positive assortative matching implies that high productivity workers and firms match together. However, there is almost no evidence of a positive correlation between the worker and firm contributions in two-way fixed-effects wage equations. This could be the result of a bias caused by standard estimation error. Using German social security records we show that the effect of this bias is substantial in samples with limited inter-firm movement. The correlation between worker and firm contributions to wage equations is unambiguously positive.

The inviscid limit and Prandtl's asymptotic expansion for incompressible flows in the half space

2022

The validity of the inviscid limit for the incompressible Navier-Stokes equations is one of the most important and challenging problems in the mathematical theory of fluid dynamics: the motion of inviscid fluids is described by the Euler equations, so, when the viscosity goes to zero, one would expect the convergence of NS solutions to the Euler solutions. However, NS equations are a singular perturbation of the Euler equations: the change of order of the equation implies that fewer boundary conditions can be imposed on the inviscid flows. Therefore, the no-slip boundary conditions, imposed on the NS solutions, are not satisfied by the Euler flow, for which a tangential slip is allowed. Thi…

Construct and predictive validity of a self-reported measure of preclinical mobility limitation.

2007

Abstract Manty M, Heinonen A, Leinonen R, Tormakangas T, Sakari-Rantala R, Hirvensalo M, von Bonsdorff MB, Rantanen T. Construct and predictive validity of a self-reported measure of preclinical mobility limitation. Objectives To validate self-reported preclinical mobility limitation concept and self-report assessment method against muscle power and walking speed, and to study the predictive validity of preclinical mobility limitation with respect to future risk of manifest mobility limitation. Design Observational prospective cohort study and cross-sectional analysis. Setting Research laboratory and community. Participants A total of 632 community-living (age range, 75−81y) women and men t…

Il principio di correttezza e buona fede come limite all’abuso di maggioranza

2016

Una delibera assembleare può essere invalidata ex art. 2479 ter c.c. per abuso di maggioranza, quando risulta fraudolentemente ed esclusivamente preordinata dai soci di maggioranza al perseguimento di una lesione degli interessi della minoranza, in violazione del principio di correttezza nell’adempimento dell’obbligazione e di buona fede nell’esecuzione del contratto. Può costituire motivo di impugnazione della delibera per conflitto di interessi l’abusivo esercizio del voto da parte di un socio che persegue un interesse personale proprio antitetico all’interesse sociale, con conseguente concreto o potenziale danno per la società. È possibile ancorare il giudizio di legittimità della delibe…

A Low-level Simulation Study of Prioritization in IEEE 802.11e Contention-based Networks

2006

This work deals with the performance evaluation of the IEEE 802.11e EDCA proposal for service prioritization in Wireless LANs. A large amount of study has been carried out in the scientific community to evaluate the performance of the EDCA proposal, mainly in terms of throughput and access delay differentiation. However, we argue that further performance insights are needed in order to fully understand the principles behind the EDCA prioritization mechanisms. To this purpose, rather than limit our investigation on throughput and delay performance figures, we take a closer look to their operation also in terms of low-level performance metrics (such as probability of accessing specific channe…

Understanding 802.11e contention-based prioritization mechanisms and their coexistence with legacy 802.11 stations

2005

The IEEE 802.11e task group has reached a stable consensus on two basic contention-based priority mechanisms to promote for standardization: usage of different arbitration interframe spaces and usage of different minimum/maximum contention windows. The goal of this article is to provide a thorough understanding of the principles behind their operation. To this purpose, rather than limit our investigation to high-level (e.g. throughput and delay) performance figures, we take a closer look at their detailed operation, also in terms of low-level performance metrics (e.g., the probability of accessing specific channel slots). Our investigation on one hand confirms that AIFS differentiation prov…

Los contratos en materia de reproducción humana asistida: especial tratamiento de la autonomía de la voluntad en las donaciones de gametos y en el de…

2022

RESUMEN: A pesar de que en nuestro país la autonomía privada preside la regulación principal en materia de contratos, ésta se encuentra ampliamente condicionada a la hora de suscribir acuerdos en materia de reproducción humana asistida. En consecuencia, es la Ley 14/2006, de 26 de mayo, la que establece ineludiblemente las pautas y requisitos que deben cumplir las partes intervinientes. De esta forma, las donaciones de gametos llevadas a cabo en nuestro país, o la toma de decisión sobre el destino que habrá de darse a los embriones crioconservados, están absolutamente marcados por la ley, dejando un escaso margen de actuación a las clínicas y usuarias que participan en estas prácticas. Por …