Glass-ionomer Adhesives in Orthodontics: Clinical Implications and Future Research Directions

During the past ten years significant advances have been made in the development of glass-ionomer bonding adhesives. The beneficial effects of fluoride are well documented and an agent which reduces or prevents a white spot lesion that commonly occurs clinically, is desirable. There has been a notable lack of randomized clinical trials to determine the prevalence of white spot lesions after orthodontic treatment although it is often reported in the literature. White spot lesions pose health and esthetic problems and their proper clinical management has yet to be resolved. The objective of this paper Is to review the literature in this area and suggest a rationale for a clinical trial to assess the efficiency of glass-ionomer adhesives in facing the problem of decalcification and study the bond strength of these materials

Systematizing Genome Privacy Research: A Privacy-Enhancing Technologies Perspective

Rapid advances in human genomics are enabling researchers to gain a better understanding of the role of the genome in our health and well-being, stimulating hope for more effective and cost efficient healthcare. However, this also prompts a number of security and privacy concerns stemming from the distinctive characteristics of genomic data. To address them, a new research community has emerged and produced a large number of publications and initiatives. In this paper, we rely on a structured methodology to contextualize and provide a critical analysis of the current knowledge on privacy-enhancing technologies used for testing, storing, and sharing genomic data, using a representative sample of the work published in the past decade. We identify and discuss limitations, technical challenges, and issues faced by the community, focusing in particular on those that are inherently tied to the nature of the problem and are harder for the community alone to address. Finally, we report on the importance and difficulty of the identified challenges based on an online survey of genome data privacy expertsComment: To appear in the Proceedings on Privacy Enhancing Technologies (PoPETs), Vol. 2019, Issue

Lawyers: Gatekeepers of the Sovereign Debt Market?

The claim that lawyers act as gatekeepers or certifiers in financial transactions is widely discussed in the legal literature. There has, however, been little empirical examination of the claim. We test the hypothesis that law firms have replaced investment banks as the gatekeepers of the market for sovereign debt. Our results suggest that hiring outside law firms sends a negative signal to the market regarding the pending issuance; a finding that is inconsistent with the thesis that outside law firms primarily play a certification role in the sovereign debt market

A Sovereign’s Cost of Capital: Go Foreign or Stay Local

A critical question faced by any sovereign seeking to raise funds in the bond market is whether to issue the debt under foreign or local parameters. This choice determines other key characteristics of any bond issue such as which banks, lawyers, and investors will be involved. Most important though, this decision involves a tradeoff between the sovereign retaining discretion in managing the issue and relinquishing control of the issue to third parties to prevent the sovereign from expropriating wealth from bondholders in the future. Based on a sample of 17,349 issuances by 117 sovereigns between 1990 and 2015, we investigate this question in the context of the initial pricing of government bonds. We examine the three key factors that bear on this decision; governing law, currency, and exchange listing. We find that highly-rated sovereigns, with strong domestic institutions that protect investors, almost always issue debt under domestic parameters. In contrast, low-rated sovereigns with weak domestic institutions tend to issue debt under foreign parameters. These findings suggest that low-quality sovereigns are forced to issue debt under foreign parameters to assure investors that the sovereign will not act opportunistically to expropriate their wealth once the debt is issued. Put differently, low-quality sovereigns that issue debt under domestic parameters face a higher cost of capital

Solving the Jitter Problem in Microwave Compressed Ultrafast Electron Diffraction Instruments: Robust Sub-50 fs Cavity-Laser Phase Stabilization

We demonstrate the compression of electron pulses in a high-brightness ultrafast electron diffraction (UED) instrument using phase-locked microwave signals directly generated from a mode-locked femtosecond oscillator. Additionally, a continuous-wave phase stabilization system that accurately corrects for phase fluctuations arising in the compression cavity from both power amplification and thermal drift induced detuning was designed and implemented. An improvement in the microwave timing stability from 100 fs to 5 fs RMS is measured electronically and the long-term arrival time stability ($>$10 hours) of the electron pulses improves to below our measurement resolution of 50 fs. These results demonstrate sub-relativistic ultrafast electron diffraction with compressed pulses that is no longer limited by laser-microwave synchronization.Comment: Accepted for publication in Structural Dynamic

Exact Solution of a Jamming Transition: Closed Equations for a Bootstrap Percolation Problem

Jamming, or dynamical arrest, is a transition at which many particles stop moving in a collective manner. In nature it is brought about by, for example, increasing the packing density, changing the interactions between particles, or otherwise restricting the local motion of the elements of the system. The onset of collectivity occurs because, when one particle is blocked, it may lead to the blocking of a neighbor. That particle may then block one of its neighbors, these effects propagating across some typical domain of size named the dynamical correlation length. When this length diverges, the system becomes immobile. Even where it is finite but large the dynamics is dramatically slowed. Such phenomena lead to glasses, gels, and other very long-lived nonequilibrium solids. The bootstrap percolation models are the simplest examples describing these spatio-temporal correlations. We have been able to solve one such model in two dimensions exactly, exhibiting the precise evolution of the jamming correlations on approach to arrest. We believe that the nature of these correlations and the method we devise to solve the problem are quite general. Both should be of considerable help in further developing this field.Comment: 17 pages, 4 figure