Systematic Review Of The Published Literature On Success And Failure Rates Of Nonsurgical Endodontic Treatment

Purpose: The aim of this study was to conduct a systematic review of the literature on treatment results in non-surgical Endodontic therapy. This included researching and defining inclusion and exclusion criteria and applying these criteria to identified relevant publications. The overall goal was to analyze the available literature and synthesize these results in an effort to inform the profession on the success and failure rates in non-surgical root canal therapy. Materials and Methods: Inclusion and exclusion criteria were established in an effort to systemically review and formulate an evidence-based understanding of treatment results in non-surgical root canal therapy. A comprehensive literature search was conducted using using PubMed and the Cochrane database using the search terms root canal therapy, apical periodontitis, success, failure, and treatment outcome and was restricted to January 2009 through December 2011. Articles were reviewed and analyzed according to the inclusion/exclusion criteria. Results: A review of the abstracts for these 330 publications resulted in 51 publications articles to be examined more closely for relevance and inclusion. From this, no publication met all defined inclusion/exclusion criteria. Discussion: Defining a set of criteria for how success is defined in practice is vital to the field of Endodontics. It is important to define, establish and incorporate a standardized methodology in the way research is conducted on Endodontic treatment results. This is necessary for the application of research to the practice of evidence-based Endodontics

Redundant screwjack

Device uses differential gears to drive either one of two nut-screw assemblies. In event that one assembly jams, second assembly is driven at twice its normal rate with no loss in overall performance

Semiclassical Approach to Heterogeneous Vacuum Decay

We derive the decay rate of an unstable phase of a quantum field theory in the presence of an impurity in the thin-wall approximation. This derivation is based on the how the impurity changes the (flat spacetime) geometry relative to case of pure false vacuum. Two examples are given that show how to estimate some of the additional parameters that enter into this heterogeneous decay rate. This formalism is then applied to the Higgs vacuum of the Standard Model (SM), where baryonic matter acts as an impurity in the electroweak Higgs vacuum. We find that the probability for heterogeneous vacuum decay to occur is suppressed with respect to the homogeneous case. That is to say, the conclusions drawn from the homogeneous case are not modified by the inclusion of baryonic matter in the calculation. On the other hand, we show that Beyond the Standard Model physics with a characteristic scale comparable to the scale that governs the homogeneous decay rate in the SM, can in principle lead to an enhanced decay rate.Comment: v3: version published in JHEP, very minor changes from v

Comment on `Magic strains in face-centered and body-centered cubic lattices'

The six symmetry-related so-called magic strain tensors that transform a f.c.c. lattice (or a b.c.c. lattice) into itself, which have been reported recently by Boyer [Acta Cryst. (1989), A45, FC29-FC32] are not unique: an infinite number of displacement tensors can be constructed that transform one lattice into another, or into itself. There is no connection with fivefold symmetry, other than that in any f.c.c. crystal

A secular increase in continental crust nitrogen during the Precambrian

Recent work indicates the presence of substantial geologic nitrogen reservoirs in the mantle and continental crust. Importantly, this geologic nitrogen has exchanged between the atmosphere and the solid Earth over time. Changes in atmospheric nitrogen (i.e. atmospheric mass) have direct effects on climate and biological productivity. It is difficult to constrain, however, the evolution of the major nitrogen reservoirs through time. Here we show a secular increase in continental crust nitrogen through Earth history recorded in glacial tills (2.9 Ga to modern), which act as a proxy for average upper continental crust composition. Archean and earliest Palaeoproterozoic tills contain 66 $\pm$ 100 ppm nitrogen, whereas Neoproterozoic and Phanerozoic tills contain 290 $\pm$ 165 ppm nitrogen, whilst the isotopic composition has remained constant at ~4\permil. Nitrogen has accumulated in the continental crust through time, likely sequestered from the atmosphere via biological fixation. Our findings support dynamic, non-steady state behaviour of nitrogen through time, and are consistent with net transfer of atmospheric N to geologic reservoirs over time.Comment: 14 pages, 2 figures, 2 tables, supplemental informatio