According to the authors, time-modified confounding occurs when the causal relation between a time-fixed or time-varying confounder and the treatment or outcome changes over time. A key difference between previously described time-varying confounding and the proposed time-modified confounding is that, in the former, the values of the confounding variable change over time while, in the latter, t...

A 42-year-old man had undergone mitral valve (MV) replacement 12 years earlier with the use of a CarboMedics bileaflet mechanical prosthesis (Sorin Biomedica). On a routine visit, he was asymptomatic, and cardiac auscultation revealed closing and opening MV clicks. A transthoracic echocardiogram with the use of a 2-beat acquisition protocol showed normal excursion of both MV discs (Figure 1; Mo...

where u ∼ N(0, G) and 2 ∼ N(0, R) with u and 2 independent. This model can be interpreted as Y |β, u ∼ N(Xβ+Zu,R), u ∼ N(0, G), yielding (on integrating out u) the marginal model Y |β ∼ N(Xβ,ZGZ + R). Let V = ZGZ + R. Then the maximum penalized likelihood estimates of β and u given G and R are given by θ̂ = [ β̂ û ] = (CTR−1C + B)−1CTR−1y (A.2) where C = [X Z] and B is the block diagonal matrix w...

Longitudinal studies, where data are repeatedly collected on one subject over a period, are common in medical research. When effect of a time-varying exposure on an outcome of interest is measured at different time points, standard statistical methods fail to give robust estimate in the presence of time-dependent confounders. There is alternative method avoid, that is, inverse probability weigh...

A concept known as ‘marginal gains’, an approach to performance improvement in elite sport came to prominence during the London 2012 Olympics when Team GB cycling won a record eight gold medals. Since National Lottery funding was awarded in 1997 to develop British cycling, the ethos of making aggregated small gains in many areas to improve overall performance has been central to its success. Th...

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the regioselective ring opening of styrene oxide using elemental iodine and bromine in the presence of disulfides as new catalysts was studied. the conductivity titration and uv spectroscopy were used to study the interaction of iodine with these catalysts. the results indicate that disulfide 11 is efficient in polyiodide formation, and can catalyze this reaction in excellent yield and high reg...

Simmel discovers the essential in unessential, and sets centre of our affairs on periphery normal life. Temporary gratification, an ubi consistam, can fact only be obtained ulteriority to which we are referred temporarily linger marginal experiences, eccentric, as yet not saturated possibilities that come meet us, a gift, or result activity entirely own – adventure, dreams, artworks. Simmel’s f...

Abstract In this paper, we introduce the notion of a marginal tube, which is hypersurface foliated by surfaces. It generalises marginally trapped tube and several notions black hole horizons, for example trapping isolated dynamical etc. We prove that if every spacelike section surface, then null. There no assumption on topology tube. To it, study geometry surfaces in four-dimensional spacetime ...

statement of the problem: although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. purpose: the purpose of this study was to evaluate the marginal fit of zirconia cad/cam ceramic crowns before and after porcelain firing. the influence of finish line configuration on the marginal f...