Mitigation of 42^{42}Ar/42^{42}K background for the GERDA Phase II experiment

Background coming from the $^{42}$Ar decay chain is considered to be one of the most relevant for the GERDA experiment, which aims to search of the neutrinoless double beta decay of $^{76}$Ge. The sensitivity strongly relies on the absence of background around the Q-value of the decay. Background coming from $^{42}$K, a progeny of $^{42}$Ar, can contribute to that background via electrons from the continuous spectrum with an endpoint of 3.5 MeV. Research and development on the suppression methods targeting this source of background were performed at the low-background test facility LArGe. It was demonstrated that by reducing $^{42}$K ion collection on the surfaces of the broad energy germanium detectors in combination with pulse shape discrimination techniques and an argon scintillation veto, it is possible to suppress the $^{42}$K background by three orders of magnitude. This is sufficient for Phase II of the GERDA experiment

The Evolving Landscape of Internet Control

Over the past two years, we have undertaken several studies at the Berkman Center designed to better understand the control of the Internet in less open societies. During the years we've been engaged in this research, we have seen many incidents that have highlighted the continuing role of the Internet as a battleground for political control, including partial or total Internet shutdowns in China, Iran, Egypt, Libya, and Syria; many hundreds of documented DDoS, hacking, and other cyber attacks against political sites; continued growth in the number of countries that filter the Internet; and dozens of well documented cases of on- and offline persecution of online dissidents. The energy dedicated to these battles for control of the Internet on both the government and dissident sides indicated, if nothing else, that both sides think that the Internet is a critical space for political action. In this paper, we offer an overview of our research in the context of these changes in the methods used to control online speech, and some thoughts on the challenges to online speech in the immediate future

Online Permaculture Resources: An Evaluation of a Selected Sample

As a newly-emerging, sustainable approach to landscape management, permaculture seeks to integrate knowledge from several disciplines into a holistic system with emphasis on ecological and social responsibility. Online resources on permaculture appear to represent a promising direction in the movement by supplementing existing printed sources, serving to update and diversify existing content, and increasing access to permaculture information and praxis among the general public. This study evaluated a sample of online resources on permaculture using a framework of parameters reflecting website usability and content quality. Best practice for website usability, as well as diversity of information and applicability, was addressed. The evaluation revealed, overall, good quality and usability in the majority of cases, and suggests a strong online presence among the existing permaculture community, and accessible support for those with an interest in joining the movement