Still tied by golden fetters: the global response to the US recession of 1937-1938

The US recession of 1937-8 is one of the deepest on record. Yet it did not produce a global depression - quite unlike 1930. According to the standard view, this reflected an unfettering of central banking after the collapse of the international gold standard circa 1931. We challenge this view. While Germany and a couple of Central and Eastern European countries were sheltered by binding exchange controls, most countries were still constrained by their golden fetters, as our new exchange rate regime classification suggests. The underlying policy regime was surprisingly similar to that of the 1929-30 downturn. What mattered was a quick reversal in US policy in 1938 and, for many countries, a more plentiful stock of international reserve

Untersuchungen zur Degradation der Metallisierung von PERC-Solarzellen

Für derzeitige, industriell hergestellte Solarmodule werden Leistungsgarantien von 20 bis 25 Jahren gegeben. Das hat hohen Ansprüchen bezüglich ihrer Zuverlässigkeit, welche sich über ihre Effizienzabnahme pro Jahr definiert, zur Folge. Die Einführung neuer Technologien, wie z.B. die der PERC- (passivated emitter and rear cell) als Ersatz für die bislang dominierende BSF-Technologie (back surface field) hat eine umfangreiche Änderung der Metallisierung der Solarzellen nach sich gezogen, wodurch neue Degradationseffekte auftreten können. In der vorliegenden Arbeit werden die einzelnen Komponenten der Solarzellenmetallisierung und –verschaltung in Bezug auf ihren Beitrag zur Degradation untersucht. Die dafür notwendige beschleunigte Alterung erfolgte mittels Temperaturwechselbelastung zwischen -40 °C und +85 °C. Unterstützt durch die numerische Simulation konnte die Degradation der Rückseitenmetallisierung und Zellverschaltung im Detail charakterisiert und Lösungen zur Reduktion der Leistungsabnahme abgeleitet werden. Erstmals wurde dabei der Einfluss der AgAl-Legierung und des Druckkontaktwiderstandes auf den Serienwiderstand der Solarmodule untersucht

Our (in)Secure Web: Understanding Update Behavior of Websites and Its Impact on Security

Software updates take an essential role in keeping IT environments secure. If service providers delay or do not install updates, it can cause unwanted security implications for their environments. This paper conducts a large-scale measurement study of the update behavior of websites and their utilized software stacks. Across 18 months, we analyze over 5.6M websites and 246 distinct client- and server-side software distributions. We found that almost all analyzed sites use outdated software. To understand the possible security implications of outdated software, we analyze the potential vulnerabilities that affect the utilized software. We show that software components are getting older and more vulnerable because they are not updated. We find that 95 % of the analyzed websites use at least one product for which a vulnerability existed

An Eisenstein ideal for imaginary quadratic fields and the Bloch-Kato conjecture for Hecke characters

For certain algebraic Hecke characters chi of an imaginary quadratic field F we define an Eisenstein ideal in a p-adic Hecke algebra acting on cuspidal automorphic forms of GL_2/F. By finding congruences between Eisenstein cohomology classes (in the sense of G. Harder) and cuspidal classes we prove a lower bound for the index of the Eisenstein ideal in the Hecke algebra in terms of the special L-value L(0,chi). We further prove that its index is bounded from above by the order of the Selmer group of the p-adic Galois character associated to chi^{-1}. This uses the work of R. Taylor et al. on attaching Galois representations to cuspforms of GL_2/F. Together these results imply a lower bound for the size of the Selmer group in terms of L(0,chi), coinciding with the value given by the Bloch-Kato conjecture.Comment: 26 page

Beyond the Front Page: Measuring Third Party Dynamics in the Field

In the modern Web, service providers often rely heavily on third parties to run their services. For example, they make use of ad networks to finance their services, externally hosted libraries to develop features quickly, and analytics providers to gain insights into visitor behavior. For security and privacy, website owners need to be aware of the content they provide their users. However, in reality, they often do not know which third parties are embedded, for example, when these third parties request additional content as it is common in real-time ad auctions. In this paper, we present a large-scale measurement study to analyze the magnitude of these new challenges. To better reflect the connectedness of third parties, we measured their relations in a model we call third party trees, which reflects an approximation of the loading dependencies of all third parties embedded into a given website. Using this concept, we show that including a single third party can lead to subsequent requests from up to eight additional services. Furthermore, our findings indicate that the third parties embedded on a page load are not always deterministic, as 50% of the branches in the third party trees change between repeated visits. In addition, we found that 93% of the analyzed websites embedded third parties that are located in regions that might not be in line with the current legal framework. Our study also replicates previous work that mostly focused on landing pages of websites. We show that this method is only able to measure a lower bound as subsites show a significant increase of privacy-invasive techniques. For example, our results show an increase of used cookies by about 36% when crawling websites more deeply

Towards Understanding First-Party Cookie Tracking in the Field

Third-party tracking is a common and broadly used technique on the Web. Different defense mechanisms have emerged to counter these practices (e. g. browser vendors that ban all third-party cookies). However, these countermeasures only target third-party trackers and ignore the first party because the narrative is that such monitoring is mostly used to improve the utilized service (e.g. analytical services). In this paper, we present a large-scale measurement study that analyzes tracking performed by the first party but utilized by a third party to circumvent standard tracking preventing techniques. We visit the top 15,000 websites to analyze first-party cookies used to track users and a technique called “DNS CNAME cloaking”, which can be used by a third party to place first-party cookies. Using this data, we show that 76% of sites effectively utilize such tracking techniques. In a long-running analysis, we show that the usage of such cookies increased by more than 50% over 2021

Excited bound states and their role in dark matter production

We explore the impact of highly excited bound states on the evolution of number densities of new physics particles, specifically dark matter, in the early Universe. Focusing on dipole transitions within perturbative, unbroken gauge theories, we develop an efficient method for including around a million bound state formation and bound-to-bound transition processes. This enables us to examine partial-wave unitarity and accurately describe the freeze-out dynamics down to very low temperatures. In the non-Abelian case, we find that highly excited states can prevent the particles from freezing out, supporting a continuous depletion in the regime consistent with perturbativity and unitarity. We apply our formalism to a simplified dark matter model featuring a colored and electrically charged $t$-channel mediator. Our focus is on the regime of superWIMP production which is commonly characterized by a mediator freeze-out followed by its late decay into dark matter. In contrast, we find that excited states render mediator depletion efficient all the way until its decay, introducing a dependence of the dark matter density on the mediator lifetime as a novel feature. The impact on the viable dark matter mass can amount to an order of magnitude, relaxing constraints from Lyman-$\alpha$ observations.Comment: 21 pages + references, 10 figure

Phylogenomics and biogeography of the world's thrushes (Aves, Turdus) : new evidence for a more parsimonious evolutionary history

To elucidate the relationships and spatial range evolution across the world of the bird genus Turdus (Aves), we produced a large genomic dataset comprising ca 2 million nucleotides for ca 100 samples representing 53 species, including over 2000 loci. We estimated time-calibrated maximum-likelihood and multispecies coalescentphylogenies and carried out biogeographic analyses. Our results indicate that there have been considerably fewer trans-oceanic dispersals within the genus Turdus than previously suggested, such that the Palaearctic clade did not originate in America and the African clade was not involved in the colonization of the Americas. Instead, our findings suggest that dispersal from the Western Palaearctic via the Antilles to the Neotropics might have occurred in a single event, giving rise to the rich Neotropical diversity of Turdus observed today, with no reverse dispersals to thePalaearctic or Africa. Our large multilocus dataset, combined with dense species-level sampling and analysed under probabilistic methods, brings important insights into historical biogeography and systematics, even in a scenario of fast and spatially complex diversification.Peer reviewe

Untersuchung der Praxistauglichkeit eines Ortungssystems zur Verbesserung des Herdenmanagements eines Milchviehbetriebes

Ziel dieses Versuches, der im Rahmen eines Praxisprojektes durchgeführt wurde, war die Überprüfung der Praxistauglichkeit des Real Time Location Systems (RTLS) Ubisense 7000 für das Herdenmanagement. Neben der Überprüfung der Genauigkeit der mit dem Ortungssystems erhobenen Daten, wurden Daten, zur Aktivitätsmessung, Brunsterkennung, Aufenthaltsdauer in den Funktionsbereichen sowie Laufverhalten mithilfe von Pedometern und Videobeobachtung erfasst