Search results for "BIAS"
showing 10 items of 654 documents
Photorefraction demonstrations using electrooptic PLZT ceramics modulators
2003
PLZT ceramics electrooptic (EO) modulator was designed for demonstrations and student's laboratory works to study photorefraction using Ar+ laser (λ = 514 nm). PLZT element had an aperture of 1.5 x 8 mm2 and thickness of 1.5 mm. Reading of recorded patterns was realized by applying to the element the biasing electric field. The most efficient writing took place for ceramics composition PLZT 8.75/65/35. The total intensity of two writing beams was up to 300 mW, the applied electric field during writing -- up to 20 kV/cm. The diffraction efficiency depended on the applied biasing reading electric field EBR . For the reading He-Ne laser the diffraction efficiency η ≈ 0.48 was obtained at the b…
JH-Operators and Occasionally Weakly g-Biased Pairs in Fuzzy Symmetric Spaces
2013
We introduce the notions of $\mathcal{JH}$-operators and occasionally weakly $g$-biased mappings in fuzzy symmetric spaces to prove common fixed point theorems for self-mappings satisfying a generalized mixed contractive condition. We also prove analogous results for two pairs of $\mathcal{JH}$-operators by assuming symmetry only on the set of points of coincidence. These results unify, extend and complement many results existing in the recent literature. We give also an application of our results to product spaces.
The MOBI-Kids Study Protocol: Challenges in Assessing Childhood and Adolescent Exposure to Electromagnetic Fields from Wireless Telecommunication Tec…
2014
The rapid increase in mobile phone use in young people has generated concern about possible health effects of exposure to radiofrequency (RF) and extremely low frequency (ELF) electromagnetic fields (EMF). MOBI-Kids, a multinational case–control study, investigates the potential effects of childhood and adolescent exposure to EMF from mobile communications technologies on brain tumor risk in 14 countries. The study, which aims to include approximately 1,000 brain tumor cases aged 10–24 years and two individually matched controls for each case, follows a common protocol and builds upon the methodological experience of the INTERPHONE study. The design and conduct of a study on EMF exposure an…
Decreased intersubject synchrony in dynamic valence ratings of sad movie contents in dysphoric individuals
2021
Emotional reactions to movies are typically similar between people. However, depressive symptoms decrease synchrony in brain responses. Less is known about the effect of depressive symptoms on intersubject synchrony in conscious stimulus-related processing. In this study, we presented amusing, sad and fearful movie clips to dysphoric individuals (those with elevated depressive symptoms) and control participants to dynamically rate the clips’ valences (positive vs. negative). We analysed both the valence ratings’ mean values and intersubject correlation (ISC). We used electrodermal activity (EDA) to complement the measurement in a separate session. There were no group differences in either t…
Bodies in the early childhood education classroom: a Bourdieusian analysis of curricular materials
2019
To our knowledge, no studies have used Bourdieu's theoretical contributions to frame investigations on how early childhood education (ECE) teaching materials construct body differences in a way that justifies gender inequality. For Bourdieu, the power to classify and grant properties and signs to subjects, does not reside only in the power to impose, but also in the degree to which the vision is anchored within reality. Therefore, the aims of this study is to assess the representation of the body in the curricular materials of ECE classrooms in 10 public centers, by means of quantitative content analysis and to provide, using Pierre Bourdieu's theoretical framework on the construction of th…
Regression with imputed covariates: A generalized missing-indicator approach
2011
A common problem in applied regression analysis is that covariate values may be missing for some observations but imputed values may be available. This situation generates a trade-off between bias and precision: the complete cases are often disarmingly few, but replacing the missing observations with the imputed values to gain precision may lead to bias. In this paper, we formalize this trade-off by showing that one can augment the regression model with a set of auxiliary variables so as to obtain, under weak assumptions about the imputations, the same unbiased estimator of the parameters of interest as complete-case analysis. Given this augmented model, the bias-precision trade-off may the…
BALANCED VARIABLE ADDITION IN LINEAR MODELS
2018
This paper studies what happens when we move from a short regression to a long regression in a setting where both regressions are subject to misspecification. In this setup, the least-squares estimator in the long regression may have larger inconsistency than the least-squares estimator in the short regression. We provide a simple interpretation for the comparison of the inconsistencies and study under which conditions the additional regressors in the long regression represent a “balanced addition” to the short regression.
Are private schools more efficient than public schools ? Evidence from Tanzania
2001
International audience; Beginning in the mid-1980s, there has been an explosive growth of private secondary schools in Tanzania. By easing constraints on private operators, the government has clearly found an effective way in the context of right public budget constraints to cope with the excess demand for this level of schooling. But has the policy also led to efficient operations in terms of student learning ? In this paper, we attempt to shed light on this issue by comparing the efficiency of four types of schools that make up the majority of schools in the country : Government and Community schools in the public sector, and Chirstian and Wazazi schools in the private sector. Using longi…
Trade Costs, Trade Balances, and Current Accounts: an application of Gravity to Multilateral Trade
2005
In this paper we test the well-known hypothesis of Obstfeld and Rogoff (NBER Macroeconomics Annual 7777:339–390, 2000) that trade costs are the key to explaining the so-called Feldstein–Horioka puzzle. Our approach has a number of novel features. First, we focus on the interrelationship between trade costs, the trade account and the Feldstein–Horioka puzzle. Second, we use the gravity model to estimate the effect of trade costs on bilateral trade and, third, we show how bilateral trade can be used to draw inferences about desired trade balances and desired intertemporal trade. Our econometric results provide strong support for the Obstfeld and Rogoff hypothesis and we are also able to recon…
Asymmetric decentralisation, economic cycle, regional and local government’s borrowing in Spain
2014
This paper investigates the evolution of sub-central government borrowing in Spain over the period 1996–2011. The arguments and figures provided show that the intense process of political and fiscal decentralisation that took place over the 1990s and 2000s did not lead to higher debt ratios in terms of GDP at these tiers of government until 2007. Although a kind of overspending bias was in effect until the late 2000s, the paper shows that the evolution of GDP and tax revenues provided regional and local governments with enough resources to vigorously pursue their devolved public policy responsibilities and still keep their debt ratios under control. However, since 2008, when the world finan…