Frontier knowledge and scientific production: evidence from the collapse of international science

We show that WWI and the subsequent boycott against Central scientists severely interrupted international scientific cooperation. After 1914, citations to recent research from abroad decreased and paper titles became less similar (evaluated by Latent Semantic Analysis), suggesting a reduction in international knowledge flows. Reduced international scientific cooperation led to a decline in the production of basic science and its application in new technology. Specifically, we compare productivity changes for scientists who relied on frontier research from abroad, to changes for scientists who relied on frontier research from home. After 1914, scientists who relied on frontier research from abroad published fewer papers in top scientific journals, produced less Nobel Prize-nominated research, introduced fewer novel scientific words, and introduced fewer novel words that appeared in the text of subsequent patent grants. The productivity of scientists who relied on top 1% research declined twice as much as the productivity of scientists who relied on top 3% research. Furthermore, highly prolific scientists experienced the starkest absolute productivity declines. This suggests that access to the very best research is key for scientific and technological progres

Politisches Kabarett und Gegenöffentlichkeit

Die vorliegende Arbeit beschäftigt sich mit den Phänomenen politisches Kabarett und Gegenöffentlichkeit. Es wird dabei der grundlegenden Frage nachgegangen, wie weit diese beiden Themen in Verbindung zueinander stehen und welche weiteren Faktoren darüber hinaus Einfluss auf diesbezügliche Korrelationen nehmen. Auf Basis der medialen Affinität beider Phänomene wird schon vorab davon ausgegangen, dass die Betrachtung eines entsprechenden medialen Rahmens in Form der Diskussion angemessener Theorien einen konstruktiven Beitrag zu den hier anzustellenden Überlegungen liefern kann. Es sollen ferner die Rollen sowohl politischen Humors, Witzes und Kabaretts wie auch gegenöffentlicher Strukturen in unterschiedlichen politischen Systemen, anhand der Beispiele Totalitarismus und Demokratie, diskutiert werden. Auch hierbei bietet sich neuerlich ein entsprechendes Framing durch die Einbeziehung medialer Theorien an. Damit wird klar, dass es letzten Endes die Medien sind, die einen Trichter formen, über den die hier diskutierten Themen zusammenlaufen müssen. Vor dem Hintergrund einer historischen Abhandlung zu den in dieser Arbeit interessierenden Phänomenen, deren Zusammenhänge und den entsprechenden rahmengebenden Strukturen soll schließlich der Versuch angegangen werden Wirkung und Einflussnahme auf soziale, politische und wirtschaftliche Geschehnisse durch politisches Kabarett und Gegenöffentlichkeit, sowie deren Funktion in den angesprochenen sozialen Subsystemen zu beleuchten. Es stellt sich im Laufe der vorliegenden Abhandlung heraus, dass die Verzahnung der hier betrachteten Phänomene insgesamt eine viel enger Ineinandergreifende ist, als dies auf den ersten Blick den Anschein haben mag. Auch die sich vor dem Hintergrund der Aussagekraft über eine Gesellschaft und ihren sozialpsychologischen Zustand ergebende gesellschaftliche Relevanz politischen Humors und gegenöffentlicher Bewegungen treten im Laufe der hier angestellten Ausführungen mehr und mehr zum Vorschein. Die vorliegende Arbeit versucht, mittels der Betrachtung im wissenschaftlichen Sinne eher ungewöhnlicher Forschungsobjekte, Einblicke darin zu gewinnen, anhand welcher Phänomene gesellschaftliche, politische und wirtschaftliche Entwicklungen sich beschreiben und genauer verstehen lassen, welche Einflüsse dabei geltend gemacht werden können und worin sich Korrelationspunkte zwischen Vergangenem, Gegenwärtigem und Zukünftigen finden lassen

Indirect Meltdown: Building Novel Side-Channel Attacks from Transient-Execution Attacks

The transient-execution attack Meltdown leaks sensitive information by transiently accessing inaccessible data during out-of-order execution. Although Meltdown is fixed in hardware for recent CPU generations, most currently-deployed CPUs have to rely on software mitigations, such as KPTI. Still, Meltdown is considered non-exploitable on current systems. In this paper, we show that adding another layer of indirection to Meltdown transforms a transient-execution attack into a side-channel attack, leaking metadata instead of data. We show that despite software mitigations, attackers can still leak metadata from other security domains by observing the success rate of Meltdown on non-secret data. With LeakIDT, we present the first cache-line granular monitoring of kernel addresses. LeakIDT allows an attacker to obtain cycle-accurate timestamps for attacker-chosen interrupts. We use our attack to get accurate inter-keystroke timings and fingerprint visited websites. While we propose a low-overhead software mitigation to prevent the exploitation of LeakIDT, we emphasize that the side-channel aspect of transient-execution attacks should not be underestimated.Comment: published at ESORICS 202

Reviving Meltdown 3a

Since the initial discovery of Meltdown and Spectre in 2017, different variants of these attacks have been discovered. One often overlooked variant is Meltdown 3a, also known as Meltdown-CPL-REG. Even though Meltdown-CPL-REG was initially discovered in 2018, the available information regarding the vulnerability is still sparse. In this paper, we analyze Meltdown-CPL-REG on 19 different CPUs from different vendors using an automated tool. We observe that the impact is more diverse than documented and differs from CPU to CPU. Surprisingly, while the newest Intel CPUs do not seem affected by Meltdown-CPL-REG, the newest available AMD CPUs (Zen3+) are still affected by the vulnerability. Furthermore, given our attack primitive CounterLeak, we show that besides up-to-date patches, Meltdown-CPL-REG can still be exploited as we reenable performance-counter-based attacks on cryptographic algorithms, break KASLR, and mount Spectre attacks. Although Meltdown-CPL-REG is not as powerful as other transient-execution attacks, its attack surface should not be underestimated.Comment: published at ESORICS 202

XMM-Newton observations of the Perseus Cluster I: The temperature and surface brightness structure

We present preliminary results of the XMM-Newton 50 ksec observation of the Perseus cluster. The global east/west asymmetry of the gas temperature and surface brightness distributions, approximately aligned with the chain of bright galaxies, suggests an ongoing merger, although the modest degree of the observed asymmetry certainly excludes a major merger interpretation. The chain of galaxies probably traces the filament along which accretion has started some time ago and is continuing at the present time. A cold and dense (low entropy) cluster core like Perseus is probably well "protected" against the penetration of the gas of infalling groups and poor clusters whereas in non-cooling core clusters like Coma and A1367, infalling subclusters can penetrate deeply into the core region. In Perseus, gas associated with infalling groups may be stripped completely at the outskirts of the main cluster and only compression waves (shocks) may reach the central regions. We argue that the passage of such a wave(s) can qualitatively explain the overall horseshoe shaped appearance of the gas temperature map (the hot horseshoe surrounds the colder, low entropy core) as well as other features of the Perseus cluster core. As compression waves traverse the cluster core, they can induce oscillatory motion of the cluster gas which can generate multiple sharp "edges", on opposite sides or the central galaxy. Gas motions induced by mergers may be a natural way to explain the high frequency of "edges" seen in clusters with cooling cores.Comment: 16 pages, 14 figures, submitted to Ap

Hammulator: Simulate Now - Exploit Later

Rowhammer, first considered a reliability issue, turned out to be a significant threat to the security of systems. Hence, several mitigation techniques have been proposed to prevent the exploitation of the Rowhammer effect. Consequently, attackers developed more sophisticated hammering and exploitation techniques to circumvent mitigations. Still, the development and testing of Rowhammer exploits can be a tedious process, taking multiple hours to get the bit flip at the correct location. In this paper, we propose Hammulator, an open-source rapid-prototyping framework for Rowhammer exploits. We simulate the Rowhammer effect using the gem5 simulator and DRAMsim3 model, with a parameterizable implementation that allows researchers to simulate various types of systems. Hammulator enables faster and more deterministic bit flips, facilitating the development of Rowhammer proof-of-concept exploits and defenses. We evaluate our simulator by reproducing 2 open-source Rowhammer exploits. We also evaluate 2 previously proposed mitigations, PARA and TRR, in our simulator. Additionally, our micro- and macrobenchmarks show that our simulator has a small average overhead in the range of 6.96 % to 10.21 %. Our results show that Hammulator can be used to compare Rowhammer exploits objectively by providing a consistent testing environment. Hammulator and all experiments and evaluations are open source, hoping to ease the research on Rowhammer

Micro-shear of silicon: Elastic strain analysis using digital image correlation

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Die Expression des Epitops Sialyl Lewis X als prognostischer Faktor beim kolorektalen Karzinom

In der hier vorliegenden Arbeit wurde die prognostische Wertigkeit der immunhistochemisch detektierten Expression des auf den Zellwänden kolorektaler Karzinome auftretenden Glykoproteinepitops Sialyl LeX analysiert. In die Untersuchung wurden 215 Patienten mit einbezogen, die sich zwischen Januar 2000 und Dezember 2004 in der Chirurgischen Universitätsklinik Rostock der primären Resektion eines kolorektalen Karzinoms im UICC-Stadium III oder IV unterzogen. Für die Auswertung der Färbung wurde ein fünfstufiger, einfach anzuwendender Score entwickelt