objectives: this study was designed to assess the changes of the mandible of patients who underwent orthodontic treatment with or without extraction of four premolars. materials and methods: eighteen class i bimaxillary protrusion patients treated with extraction of four first premolars and retraction of anterior teeth and 18 class i non-extraction patients with a mean age of 16.38±0.4 years we...

In Hard Disk Drives (HDD), it is necessary to decrease the Flying Height (FH) between the head and the disk (currently, FH is around 3-5 nm) so as to increase recording densities. Retaining the solid lubricant has become a difficult proposition owing to intermittent contact between the surfaces. ZTMD and Z are used as solid lubricant to lubricate these interfaces. In this paper, the behavior of...

This paper investigates the instance complexities of problems that are hard or weakly hard for exponential time under polynomial time many one reductions It is shown that almost every instance of almost every problem in exponential time has essentially maximal instance complexity It follows that every weakly hard problem has a dense set of such maximally hard instances This extends the theorem ...

We study Abusch’s (2002; 2010) distinction between hard and soft triggers from an experimental point of view. We show that there are apparent counterexamples to the distinction, discuss their status and describe future experiments aiming at clarifying the processing issues that form the core of the problem.

We resum distributions that are singular at partonic threshold (the elastic limit) in heavy quark production, in terms of logarithmic behavior in moment space. The method may be applied to a variety of cross sections sensitive to the edge of phase space, including transverse momentum distributions. Beyond leading logarithm, dependence on the moment variable is controlled by a matrix renormaliza...

We consider the problem of generating hard instances for the Satisfying Assignment Search Problem (in short, SAT). It is not known whether SAT is difficult on average, while it has been believed that the Factorization Problem (in short, FACT) is hard on average. Thus, one can expect to generate hard-on-average instances by using a reduction from FACT to SAT. Although the asymptotically best red...