Search results for "points"
showing 10 items of 415 documents
Booms, Busts and normal times in the housing market
2015
We assess the existence of duration dependence in the likelihood of an end in housing booms, busts, and normal times. Using data for 20 industrial countries and a continuous-time Weibull duration model, we find evidence of positive duration dependence suggesting that housing market cycles have become longer over the last decades. Then, we extend the baseline Weibull model and allow for the presence of a change-point in the duration dependence parameter.We show that positive duration dependence is present in booms and busts that last less than 26 quarters, but that does not seem to be the case for longer phases of the housing market cycle. For normal times, no evidence of change-points is fo…
Change-points detection for variance piecewise constant models
2011
A new approach based on the fit of a generalized linear regression model is introduced for detecting change-points in the variance of heteroscedastic Gaussian variables, with piecewise constant variance function. This approach overcome some limitations of both exact and approximate well-known methods that are based on successive application of search and tend to overestimate the real number of changes in the variance of the series. The proposed method just requires the computation of a gamma GLM with log-link, resulting in a very efficient algorithm even with large sample size and many change points to be estimated.
Wardowski conditions to the coincidence problem
2015
In this article we first discuss the existence and uniqueness of a solution for the coincidence problem: Find p ∈ X such that Tp = Sp, where X is a nonempty set, Y is a complete metric space, and T, S:X → Y are two mappings satisfying a Wardowski type condition of contractivity. Later on, we will state the convergence of the Picard-Juncgk iteration process to the above coincidence problem as well as a rate of convergence for this iteration scheme. Finally, we shall apply our results to study the existence and uniqueness of a solution as well as the convergence of the Picard-Juncgk iteration process toward the solution of a second order differential equation. Ministerio de Economía y Competi…
Government Size, the Role of Commitments*
2011
We explore the hypothesis that long-term commitments affect the dynamics of government expenditure. With the aid of a simple median-voter model we interpret the pattern of increasing-then-constant tax rates observed in OECD countries in the second half of the last century: persistence of public expenditure and a lower bound on new interventions will push government size upward, and preferences of the electorate put a halt to this growth at some point. In this view, the fiscal policy variable is seen to consist of only a part of the total expenditure, the rest being predetermined by its past level.
Non-Hermitian Physics and Master Equations
2022
A longstanding tool to characterize the evolution of open Markovian quantum systems is the GKSL (Gorini-Kossakowski-Sudarshan-Lindblad) master equation. However, in some cases, open quantum systems can be effectively described with non-Hermitian Hamiltonians, which have attracted great interest in the last twenty years due to a number of unconventional properties, such as the appearance of exceptional points. Here, we present a short review of these two different approaches aiming in particular to highlight their relation and illustrate different ways of connecting non-Hermitian Hamiltonian to a GKSL master equation for the full density matrix.
Efficient change point detection in genomic sequences of continuous measurements
2010
Abstract Motivation: Knowing the exact locations of multiple change points in genomic sequences serves several biological needs, for instance when data represent aCGH profiles and it is of interest to identify possibly damaged genes involved in cancer and other diseases. Only a few of the currently available methods deal explicitly with estimation of the number and location of change points, and moreover these methods may be somewhat vulnerable to deviations of model assumptions usually employed. Results: We present a computationally efficient method to obtain estimates of the number and location of the change points. The method is based on a simple transformation of data and it provides re…
Gold(I) Biscarbene Complexes Derived from Vascular-Disrupting Combretastatin A-4 Address Different Targets and Show Antimetastatic Potential
2014
Gold N-heterocyclic carbene (NHC) complexes are an emerging class of anticancer drugs. We present a series of gold(I) biscarbene complexes with NHC ligands derived from the plant metabolite combretastatin A-4 (CA-4) that retain its vascular-disrupting effect, yet address different cellular and protein targets. Unlike CA-4, these complexes did not interfere with tubulin, but with the actin cytoskeleton of endothelial and cancer cells. For the highly metastatic 518A2 melanoma cell line this effect was accompanied by a marked accumulation of cells in the G1 phase of the cell cycle and a suppression of active prometastatic matrix metalloproteinase-2. Despite these mechanistic differences the co…
CEO satisfaction and intended strategic changes
2018
How do CEOs react to attainment discrepancies in their organizations' performance? Scholars have generally argued that (only) when performance falls below a certain aspiration level do CEOs intend to change the organization's strategy. However, empirical evidence on this issue is ambiguous and inconclusive. We address this puzzle directly by studying how CEOs' cognitive interpretations of performance (their satisfaction with the firm's performance) affect the magnitude of intended strategic changes, and we explore the moderating effect of the context (performance compared to the industry) on this relationship. Using a sample of medium-sized organizations, we find that CEOs' satisfaction wit…
Two non-zero solutions for Sturm–Liouville equations with mixed boundary conditions
2019
Abstract In this paper, we establish the existence of two non-zero solutions for a mixed boundary value problem with the Sturm–Liouville equation. The approach is based on a recent two critical point theorem.
Mobile Telephony in Emerging Markets: The Importance of Multi-Simming Customers
2015
Rapidly increasing sales of multi-SIM phones, mobile penetration rates above 100% and reported customer behavior all point to the fact that a signicant share of mobile customers in emerging markets tend to use more than one SIM card. A primary motive for this is to avoid making expensive o-net calls. We add a segment of exible prepaid customers, who choose to "multi-sim" in equilibrium, to the seminal model of competing telephone networks a la Laont,