Immediate performance of self-etching versus system adhesives with multiple light-activated restoratives

Objectives: The purpose of this study was to evaluate the performance of both single and double applications of (Adper Prompt L-Pop) self-etching dental adhesive, when used with three classes of light-activated restorative materials, in comparison to the performance of each restorative system adhesive. Evaluation parameters to be considered for the adhesive systems were (a) immediate marginal adaptation (or gap formation) in tooth cavities, (b) free setting shrinkage-strain determined by the immediate marginal gap-width in a non-bonding Teflon cavity, and (c) their immediate shear bond-strengths to enamel and to dentin. Methods: The maximum marginal gap-width and the opposing-width (if any) in the tooth cavities and in the Teflon cavities were measured immediately (3 min) after light-activation. The shear bond-strengths to enamel and to dentin were also measured at 3 min. Results: For light-activated restorative materials during early setting (&#60;3 min), application of Adper Prompt L-Pop exhibited generally superior marginal adaptation to most system adhesives. But there was no additional benefit from double application. The marginal-gaps in tooth cavities and the marginal-gaps in Teflon cavities were highly correlated (r=0.86–0.89, p&#60;0.02–0.01). For enamel and dentin shear bond-strengths, there were no significant differences between single and double applications, for all materials tested except Toughwell and Z 250 with enamel. Significance: Single application of a self-etch adhesive was a feasible and beneficial alternative to system adhesives for several classes of restorative. Marginal gap-widths in tooth cavities correlated more strongly with free shrinkage-strain magnitudes than with bond-strengths to tooth structure.</p

On the infimum attained by a reflected L\'evy process

This paper considers a L\'evy-driven queue (i.e., a L\'evy process reflected at 0), and focuses on the distribution of $M(t)$, that is, the minimal value attained in an interval of length $t$ (where it is assumed that the queue is in stationarity at the beginning of the interval). The first contribution is an explicit characterization of this distribution, in terms of Laplace transforms, for spectrally one-sided L\'evy processes (i.e., either only positive jumps or only negative jumps). The second contribution concerns the asymptotics of \prob{M(T_u)> u} (for different classes of functions $T_u$ and $u$ large); here we have to distinguish between heavy-tailed and light-tailed scenarios

Decentralised Learning MACs for Collision-free Access in WLANs

By combining the features of CSMA and TDMA, fully decentralised WLAN MAC schemes have recently been proposed that converge to collision-free schedules. In this paper we describe a MAC with optimal long-run throughput that is almost decentralised. We then design two \changed{schemes} that are practically realisable, decentralised approximations of this optimal scheme and operate with different amounts of sensing information. We achieve this by (1) introducing learning algorithms that can substantially speed up convergence to collision free operation; (2) developing a decentralised schedule length adaptation scheme that provides long-run fair (uniform) access to the medium while maintaining collision-free access for arbitrary numbers of stations

'I like money, I like many things'. The relationship between drugs and crime from the perspective of young people in contact with criminal justice systems

Based on research undertaken as part of the EU funded EPPIC project, this paper aims to update and elaborate on the relationship between drug use and offending behaviours by exploring variations within a cross-national sample of drug-experienced young people in touch with criminal justice systems. Adopting a trajectory-based approach, interviews were undertaken with 198 young people aged 15–25 in six European countries (Austria, Denmark, Germany, Italy, Poland, and UK). Data were analysed by applying the Bennett and Holloway categorization of the drugs-crime link, with a focus on the concept of social exclusion as developed by Seddon. Three main types of mechanisms (economic, pharmaceutical, and lifestyles) are used to interpret the data, showing how the relationship between drugs and offending can vary according to type of substances and over time. Furthermore, it can be associated with very different degrees of social exclusion and needs. The results suggest that while economic inequalities still play key roles in explaining drug use and offending, both behaviours can originate from a state of relative deprivation, resulting from the contradictions inherent in ‘bulimic societies’ that raise aspirations and desires while providing young people scarce opportunities for self-realisation and social recognition

Large deviations for a damped telegraph process

In this paper we consider a slight generalization of the damped telegraph process in Di Crescenzo and Martinucci (2010). We prove a large deviation principle for this process and an asymptotic result for its level crossing probabilities (as the level goes to infinity). Finally we compare our results with the analogous well-known results for the standard telegraph process

A L\'evy input fluid queue with input and workload regulation

We consider a queuing model with the workload evolving between consecutive i.i.d.\ exponential timers $\{e_q^{(i)}\}_{i=1,2,...}$ according to a spectrally positive L\'evy process $Y_i(t)$ that is reflected at zero, and where the environment $i$ equals 0 or 1. When the exponential clock $e_q^{(i)}$ ends, the workload, as well as the L\'evy input process, are modified; this modification may depend on the current value of the workload, the maximum and the minimum workload observed during the previous cycle, and the environment $i$ of the L\'evy input process itself during the previous cycle. We analyse the steady-state workload distribution for this model. The main theme of the analysis is the systematic application of non-trivial functionals, derived within the framework of fluctuation theory of L\'evy processes, to workload and queuing models

Convergence of the all-time supremum of a L\'evy process in the heavy-traffic regime

In this paper we derive a technique of obtaining limit theorems for suprema of L\'evy processes from their random walk counterparts. For each $a>0$, let $\{Y^{(a)}_n:n\ge 1\}$ be a sequence of independent and identically distributed random variables and $\{X^{(a)}_t:t\ge 0\}$ be a L\'evy processes such that $X_1^{(a)}\stackrel{d}{=} Y_1^{(a)}$, $\mathbb E X_1^{(a)}<0$ and $\mathbb E X_1^{(a)}\uparrow0$ as $a\downarrow0$. Let $S^{(a)}_n=\sum_{k=1}^n Y^{(a)}_k$. Then, under some mild assumptions, $\Delta(a)\max_{n\ge 0} S_n^{(a)}\stackrel{d}{\to} R\iff\Delta(a)\sup_{t\ge 0} X^{(a)}_t\stackrel{d}{\to} R$, for some random variable $R$ and some function $\Delta(\cdot)$. We utilize this result to present a number of limit theorems for suprema of L\'evy processes in the heavy-traffic regime