Using backward means to eliminate individual effects from dynamic panels

The within-groups estimator is inconsistent in dynamic panels with fixed T since the sample mean used to eliminate the individual effects from the lagged dependent variable is correlated with the error term. This paper suggests to eliminate individual effects from an AR(1) panel using backward means as an alternative to sample means. Using orthogonal deviations of the lagged dependent variable from its backward mean yields an estimator that is still inconsistent for fixed T but the inconsistency is shown to be negligibly small. A Monte Carlo simulation shows that this alternative estimator has superior small sample properties compared to conventional fixed effects, bias-corrected fixed effects and GMM estimators. Interestingly, it is also consistent for fixed T in the specific cases where (i) T = 2, (ii) the AR parameter is 0 or 1, (iii) the variance of the individual effects is zero

Emotion regulation difficulties related to depression and anxiety : a network approach to model relations among symptoms, positive reappraisal, and repetitive negative thinking

Frequent repetitive negative thinking and infrequent positive reappraisal use are theorized to increase risk for depression and anxiety. Yet, research has studied these regulatory strategies at the disorder level, ignoring the clinical heterogeneity and differential relations among their individual symptoms. In this study, we examined the associations among repetitive negative thinking, positive reappraisal, and individual symptoms of depression and anxiety disorders. Models of regularized partial-correlation networks were estimated using cross-sectional data from 468 participants. Results showed that repetitive negative thinking and positive reappraisal were differentially related to affective, cognitive, and somatic symptoms of depression and anxiety. Moreover, repetitive negative thinking was more central than positive reappraisal with stronger connections to individual symptoms. Finally, repetitive negative thinking was more important than positive reappraisal in connecting clusters of depression and anxiety symptoms. These findings cast light on potential pathways through which repetitive negative thinking and positive reappraisal may operate within depression and anxiety

Is the impact of labour taxes on unemployment asymmetric?

This paper tests whether the impact of labour taxes on unemployment is symmetric with respect to increases and decreases in labour taxes. Using a panel of 16 OECD countries over the period 1970-2005, we estimate a panel unobserved component model to account for the fact that unemployment rates and labour taxes are non-stationary but not cointegrated. We find a positive impact of tax increases in European and Nordic countries with some evidence that tax decreases have a more moderate impact. For Anglo-Saxon countries, no impact of labour taxes on unemployment is found

Monotone-light factorisation systems and torsion theories

Given a torsion theory (Y,X) in an abelian category C, the reflector I from C to the torsion-free subcategory X induces a reflective factorisation system (E, M) on C. It was shown by A. Carboni, G.M. Kelly, G. Janelidze and R. Par\'e that (E, M) induces a monotone-light factorisation system (E',M*) by simultaneously stabilising E and localising M, whenever the torsion theory is hereditary and any object in C is a quotient of an object in X. We extend this result to arbitrary normal categories, and improve it also in the abelian case, where the heredity assumption on the torsion theory turns out to be redundant. Several new examples of torsion theories where this result applies are then considered in the categories of abelian groups, groups, topological groups, commutative rings, and crossed modules.Comment: 12 page

Effect of β-lactamase inhibitors on in vitro activity of β-lactam antibiotics against Burkholderia cepacia complex species

Background: Bacteria belonging to the Burkholderia cepacia complex (Bcc) are an important cause of chronic respiratory tract infections in cystic fibrosis patients. Intrinsic resistance to a wide range of antimicrobial agents, including a variety of beta-lactam antibiotics, is frequently observed in Bcc strains. Resistance to beta-lactams is most commonly mediated by efflux pumps, alterations in penicillin-binding proteins or the expression of beta-lactamases. beta-lactamase inhibitors are able to restore the in vitro activity of beta-lactam molecules against a variety of Gram-negative species, but the effect of these inhibitors on the activity of beta-lactam treatment against Bcc species is still poorly investigated. Methods: In the present study, the susceptibility of a panel of Bcc strains was determined towards the beta-lactam antibiotics ceftazidime, meropenem, amoxicillin, cefoxitin, cefepime and aztreonam; alone or in combination with a beta-lactamase inhibitor (clavulanic acid, sulbactam, tazobactam and avibactam). Consequently, beta-lactamase activity was determined for active beta-lactam/beta-lactamase inhibitor combinations. Results: Clavulanic acid had no effect on minimum inhibitory concentrations, but addition of sulbactam, tazobactam or avibactam to ceftazidime, amoxicillin, cefoxitin, cefepime or aztreonam leads to increased susceptibility (at least 4-fold MIC-decrease) in some Bcc strains. The effect of beta-lactamase inhibitors on beta-lactamase activity is both strain-and/or antibiotic-dependent, and other mechanisms of beta-lactam resistance (besides production of beta-lactamases) appear to be important. Conclusions: Considerable differences in susceptibility of Bcc strains to beta-lactam antibiotics were observed. Results obtained in the present study suggest that resistance of Bcc strains against beta-lactam antibiotics is mediated by both beta-lactamases and non-beta-lactamase-mediated resistance mechanisms

Some aspects of semi-abelian homology and protoadditive functors

In this note some recent developments in the study of homology in semi-abelian categories are briefly presented. In particular the role of protoadditive functors in the study of Hopf formulae for homology is explained.Comment: 7 page

Galois theory and commutators

We prove that the relative commutator with respect to a subvariety of a variety of Omega-groups introduced by the first author can be described in terms of categorical Galois theory. This extends the known correspondence between the Froehlich-Lue and the Janelidze-Kelly notions of central extension. As an example outside the context of Omega-groups we study the reflection of the category of loops to the category of groups where we obtain an interpretation of the associator as a relative commutator.Comment: 14 page

Measuring inflation persistence: a structural time series approach

Time series estimates of inflation persistence incur an upward bias if shifts in the inflation target of the central bank remain unaccounted for. Using a structural time series approach we measure different sorts of inflation persistence allowing for an unobserved timevarying inflation target. Unobserved components are identified using Kalman filtering and smoothing techniques. Posterior densities of the model parameters and the unobserved components are obtained in a Bayesian framework based on importance sampling. We find that inflation persistence, expressed by the halflife of a shock, can range from 1 quarter in case of a costpush shock to several years for a shock to longrun inflation expectations or the output gap.Inflation persistence, inflation target, Kalman filter, Bayesian analysis.