Ökonomische Analyse der Modernisierungsanreize im deutschen Mietrecht

Die deutsche Wohnungswirtschaft unterliegt einer tiefgreifenden staatlichen Regulierung. Hiervon sind insbesondere Heizungsanlagen betroffen. Durch die vorgeschriebene Aufteilung in Kaltmiete und Nebenkosten stellt sich die Investition in eine neue, effiziente Heizungsanlage für den Vermieter als nicht mehr wirtschaftlich dar. Auch die vom Gesetzgeber eingeräumte Möglichkeit, einen Teil der Investitionskosten jährlich auf den Mieter umzulegen, vermag den Modernisierungsstau nicht zu überwinden, wie empirische Daten zeigen. Der Beitrag untersucht vor diesem Hintergrund die Wirkung der gesetzlichen Modernisierungsanreize aus betriebswirtschaftlicher und spieltheoretischer Sicht. Es kann gezeigt werden, dass der momentane Modernisierungsstau eine plausible Folge rationalen Handelns aller Marktakteure ist. Summary: German residential leases and their associated fringe costs such as heating are subject to strict regulations. Because of the mandatory rental cost allocation into basic rent and associated costs, investments in new and efficient heating systems turned out to be no longer economical for landlords. In order to still ensure a high efficiency level of heating systems, the legislator gives landlords the opportunity to pass on some of the investment costs annually to tenants. Nevertheless, as shown by empirical data, the backlog of modernization has not been over- come yet. Against this background, we analyse the impact of the current statutory incentives for modernization from an economic and game theoretic point of view. It can be shown that the existing backlog of modernization is a plausible consequence of rational behavior of all market actors. Key words: Tenancy law, Modernization incentives, Regulation, Housing industry, Energy efficiency, Free rider problem, Game theoryMietrecht, Modernisierungsanreize, Regulierung, Wohnungswirtschaft, Energieeffizienz, Free-Rider-Problem, Spieltheorie

A Multi-perspective Analysis of Carrier-Grade NAT Deployment

As ISPs face IPv4 address scarcity they increasingly turn to network address translation (NAT) to accommodate the address needs of their customers. Recently, ISPs have moved beyond employing NATs only directly at individual customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply address translation to many independent and disparate endpoints spanning physical locations, a phenomenon that so far has received little in the way of empirical assessment. In this work we present a broad and systematic study of the deployment and behavior of these middleboxes. We develop a methodology to detect the existence of hosts behind CGNs by extracting non-routable IP addresses from peer lists we obtain by crawling the BitTorrent DHT. We complement this approach with improvements to our Netalyzr troubleshooting service, enabling us to determine a range of indicators of CGN presence as well as detailed insights into key properties of CGNs. Combining the two data sources we illustrate the scope of CGN deployment on today's Internet, and report on characteristics of commonly deployed CGNs and their effect on end users

Erfolgskontrolle von Hartholzauenwald-Aufforstungen in der Kliekener Aue

Hartholz-Auenwälder (Querco-Ulmetum minoris und weitere Vegetationseinheiten des Ulmenion) sind charakteristische Vegetationsgesellschaften entlang der großen Flussauen und wichtige Retentionsräume. Bedingt durch den Wechsel von Überflutung und Trockenheit sowie eine hohe standörtliche Dynamik und Heterogenität sind Hartholz-Auenwälder die struktur- und artenreichsten Lebensräume in Mitteleuropa. In früheren Jahrhunderten wurden viele Auenwälder zu Gunsten von Siedlungen und landwirtschaftlichen Nutzflächen gerodet, was eine erhebliche Verringerung des Flächenanteils der Auenwälder zur Folge hatte. Die verbliebenen Hartholz-Auenwälder wurden im 19. Jahrhundert durch zahlreiche wasserbaulichen Maßnahmen beeinträchtigt. Angesichts der hohen naturschutzfachlichen Bedeutung regelmäßig überfluteter Hartholz-Auenwälder und ihres heute geringen Flächenanteiles ist deren Erhaltung, Entwicklung und Erweiterung ein wesentliches Ziel des Naturschutzes in Flusslandschaften. Ziel des von der Biosphärenreservatsverwaltung „Mittlere Elbe“ 2000/2001 durchgeführten EU-LIFE-Projektes „Renaturierung von Fluss, Altwasser und Auenwald an der Mittleren Elbe“ war u. a. die Entwicklung von ca. 60 ha Auenwald auf ehemals beweideten Alteichenbeständen und Grünland. Da bisher Erfolgskontrollen von Hartholz-Auenwaldanpflanzungen fast vollständig fehlen, erfolgte 2007 eine flächendeckende Erhebung des aktuellen Zustandes aller gepflanzten Gehölzbestände in der Kliekener Aue

Hiding in Plain Sight: A Longitudinal Study of Combosquatting Abuse

Domain squatting is a common adversarial practice where attackers register domain names that are purposefully similar to popular domains. In this work, we study a specific type of domain squatting called "combosquatting," in which attackers register domains that combine a popular trademark with one or more phrases (e.g., betterfacebook[.]com, youtube-live[.]com). We perform the first large-scale, empirical study of combosquatting by analyzing more than 468 billion DNS records---collected from passive and active DNS data sources over almost six years. We find that almost 60% of abusive combosquatting domains live for more than 1,000 days, and even worse, we observe increased activity associated with combosquatting year over year. Moreover, we show that combosquatting is used to perform a spectrum of different types of abuse including phishing, social engineering, affiliate abuse, trademark abuse, and even advanced persistent threats. Our results suggest that combosquatting is a real problem that requires increased scrutiny by the security community.Comment: ACM CCS 1

Roll, Roll, Roll your Root:A Comprehensive Analysis of the First Ever DNSSEC Root KSK Rollover

The DNS Security Extensions (DNSSEC) add authenticity and integrity to the naming system of the Internet. Resolvers that validate information in the DNS need to know the cryptographic public key used to sign the root zone of the DNS. Eight years after its introduction and one year after the originally scheduled date, this key was replaced by ICANN for the first time in October 2018. ICANN considered this event, called a rollover, "an overwhelming success" and during the rollover they detected "no significant outages". In this paper, we independently follow the process of the rollover starting from the events that led to its postponement in 2017 until the removal of the old key in 2019. We collected data from multiple vantage points in the DNS ecosystem for the entire duration of the rollover process. Using this data, we study key events of the rollover. These events include telemetry signals that led to the rollover being postponed, a near real-time view of the actual rollover in resolvers and a significant increase in queries to the root of the DNS once the old key was revoked. Our analysis contributes significantly to identifying the causes of challenges observed during the rollover. We show that while from an end-user perspective, the roll indeed passed without major problems, there are many opportunities for improvement and important lessons to be learned from events that occurred over the entire duration of the rollover. Based on these lessons, we propose improvements to the process for future rollovers

Adaptation to flood risk: Results of international paired flood event studies

As flood impacts are increasing in large parts of the world, understanding the primary drivers of changes in risk is essential for effective adaptation. To gain more knowledge on the basis of empirical case studies, we analyze eight paired floods, that is, consecutive flood events that occurred in the same region, with the second flood causing significantly lower damage. These success stories of risk reduction were selected across different socioeconomic and hydro-climatic contexts. The potential of societies to adapt is uncovered by describing triggered societal changes, as well as formal measures and spontaneous processes that reduced flood risk. This novel approach has the potential to build the basis for an international data collection and analysis effort to better understand and attribute changes in risk due to hydrological extremes in the framework of the IAHSs Panta Rhei initiative. Across all case studies, we find that lower damage caused by the second event was mainly due to significant reductions in vulnerability, for example, via raised risk awareness, preparedness, and improvements of organizational emergency management. Thus, vulnerability reduction plays an essential role for successful adaptation. Our work shows that there is a high potential to adapt, but there remains the challenge to stimulate measures that reduce vulnerability and risk in periods in which extreme events do not occur

Adaptation to flood risk - results of international paired flood event studies

As flood impacts are increasing in large parts of the world, understanding the primary drivers of changes in risk is essential for effective adaptation. To gain more knowledge on the basis of empirical case studies, we analyze eight paired floods, that is, consecutive flood events that occurred in the same region, with the second flood causing significantly lower damage. These success stories of risk reduction were selected across different socioeconomic and hydro‐climatic contexts. The potential of societies to adapt is uncovered by describing triggered societal changes, as well as formal measures and spontaneous processes that reduced flood risk. This novel approach has the potential to build the basis for an international data collection and analysis effort to better understand and attribute changes in risk due to hydrological extremes in the framework of the IAHSs Panta Rhei initiative. Across all case studies, we find that lower damage caused by the second event was mainly due to significant reductions in vulnerability, for example, via raised risk awareness, preparedness, and improvements of organizational emergency management. Thus, vulnerability reduction plays an essential role for successful adaptation. Our work shows that there is a high potential to adapt, but there remains the challenge to stimulate measures that reduce vulnerability and risk in periods in which extreme events do not occur

Specific inhibition of diverse pathogens in human cells by synthetic microRNA-like oligonucleotides inferred from RNAi screens

Systematic genetic perturbation screening in human cells remains technically challenging. Typically, large libraries of chemically synthesized siRNA oligonucleotides are used, each designed to degrade a specific cellular mRNA via the RNA interference (RNAi) mechanism. Here, we report on data from three genome-wide siRNA screens, conducted to uncover host factors required for infection of human cells by two bacterial and one viral pathogen. We find that the majority of phenotypic effects of siRNAs are unrelated to the intended “on-target” mechanism, defined by full complementarity of the 21-nt siRNA sequence to a target mRNA. Instead, phenotypes are largely dictated by “off-target” effects resulting from partial complementarity of siRNAs to multiple mRNAs via the “seed” region (i.e., nucleotides 2–8), reminiscent of the way specificity is determined for endogenous microRNAs. Quantitative analysis enabled the prediction of seeds that strongly and specifically block infection, independent of the intended on-target effect. This prediction was confirmed experimentally by designing oligos that do not have any on-target sequence match at all, yet can strongly reproduce the predicted phenotypes. Our results suggest that published RNAi screens have primarily, and unintentionally, screened the sequence space of microRNA seeds instead of the intended on-target space of protein-coding genes. This helps to explain why previously published RNAi screens have exhibited relatively little overlap. Our analysis suggests a possible way of identifying “seed reagents” for controlling phenotypes of interest and establishes a general strategy for extracting valuable untapped information from past and future RNAi screens