Rapidgzip: Parallel Decompression and Seeking in Gzip Files Using Cache Prefetching

Gzip is a file compression format, which is ubiquitously used. Although a multitude of gzip implementations exist, only pugz can fully utilize current multi-core processor architectures for decompression. Yet, pugz cannot decompress arbitrary gzip files. It requires the decompressed stream to only contain byte values 9-126. In this work, we present a generalization of the parallelization scheme used by pugz that can be reliably applied to arbitrary gzip-compressed data without compromising performance. We show that the requirements on the file contents posed by pugz can be dropped by implementing an architecture based on a cache and a parallelized prefetcher. This architecture can safely handle faulty decompression results, which can appear when threads start decompressing in the middle of a gzip file by using trial and error. Using 128 cores, our implementation reaches 8.7 GB/s decompression bandwidth for gzip-compressed base64-encoded data, a speedup of 55 over the single-threaded GNU gzip, and 5.6 GB/s for the Silesia corpus, a speedup of 33 over GNU gzip.Comment: HPDC'2

Anonymität im Internet - rechtliche und tatsächliche Rahmenbedingungen : Zum Spannungsfeld zwischen einem Recht auf Anonymität bei der elektronischen Kommunikation und den Möglichkeiten zur Identifizierung und Strafverfolgung

Das Internet ermöglicht es, geschützt über Kontinente hinweg zu kommunizieren und Informationen unzensiert zu verbreiten sowie abzurufen. Gleichzeitig können im Schutz der (oftmals nur scheinbaren) Anonymität des Internet aber auch Straftaten begangen werden, die sich nur schwer und in einigen Fällen gar nicht mehr verfolgen lassen. Sowohl die rechtlichen Rahmenbedingungen – aufgrund der Transnationalität nicht nur in Deutschland, sondern auch in weiteren Ländern – als auch die technischen Gegebenheiten spielen in beiden Fällen für die tatsächliche Anonymität eine wichtige Rolle. Die vorliegende Arbeit verbindet zwei Bereiche, die sonst häufig als Gegenpole oder sogar als unvereinbar dargestellt werden: Recht und Technik. Es wird umfassend untersucht, welchen Schutz die geltende Gesetzeslage Bürgern bietet, die – aus welchen Gründen auch immer – anonym bleiben möchten. Zum anderen geht der Autor darauf ein, welche technischen Möglichkeiten gegenwärtig zur Verfügung stehen, um identifizierende Spuren bei der Nutzung des Internet zu vermeiden. Erst die Zusammenschau von rechtlich gewährtem Rahmen für Anonymität und technischen Möglichkeiten, sie herzustellen (oder sie zu brechen), ermöglicht einen umfassenden Blick auf den gegenwärtigen Status quo der elektronischen Anonymität in Deutschland. Die Ergebnisse der Arbeit sind daher nicht nur für Personen interessant, die vermeiden möchten, dass ihre personenbezogenen Daten umfassend überwacht und ausgewertet werden. Auch für den Gesetzgeber und die mit der Auslegung des inzwischen unüberschaubar gewordenen Regelungsgeflechts zu Datenschutz und Überwachung befassten Richter, Staats- und Rechtsanwälte ergeben sich wichtige Impulse

Cyano-tryptophans as dual infrared and fluorescence spectroscopic labels to assess structural dynamics in proteins

The steady state and time-resolved fluorescence and infrared (IR) properties of 4- and 5-cyanotryptophan (CNTrp) are investigated and compared, and the tryptophan (Trp) analogs are found to be very attractive to study structural and dynamic properties of proteins. The position of the nitrile substitution as well as the solvent environment influences the spectroscopic properties (solvatochromism). Similar to native Trp, electronic (nanosecond) lifetime and emission spectra are modulated by the environment, making CNTrps attractive fluorescent probes to study the structural dynamics of proteins in complex media. The nitrile absorption in the IR region can provide local structural information as it responds sensitively to changes in electrostatics and hydrogen bond (HB) interactions. Importantly, we find that 4CNTrp exhibits a single absorption in the nitrile stretch region, while the model compound 4CN-indole (4CNI) shows two. Even though the spectrum of the model compound is perturbed by a Fermi resonance, we find that 4CNTrp itself is a useful IR label. Moreover, if the nitrile group is substituted at the 5 position, the Trp analog predominantly reports on its HB status. Because the current literature on similar compounds is too limited for a detailed solvatochromic analysis, we extend the available data significantly. Only now are microscopic details such as the mentioned sensitivity to electrostatics coming to light. The vibrational lifetime of the CN moiety (acting on a picosecond time scale in contrast to the nanosecond time scale for fluorescent emission) allows for its application in 2D-IR spectroscopy in the low picosecond range. Taken together, the benefits of CNTrps are that they absorb and emit separately from the naturally occurring Trp and that in these dual fluorescence/vibrational labels, observables of IR and fluorescence spectroscopy are modulated differently by their surroundings. Because IR absorption and fluorescence operate on different time and length scales, they thus provide complementary structural information.</p

Effects of Prenatal Social Stress and Maternal Dietary Fatty Acid Ratio on Infant Temperament: Does Race Matter?

Background: Infant temperament predicts a range of developmental and behavioral outcomes throughout childhood. Both maternal fatty acid intake and psychosocial stress exposures during pregnancy may influence infant temperament. Furthermore, maternal race may modify prenatal diet and stress effects. The goals of this study are to examine the joint effects of prenatal diet and stress and the modifying effects of race on infant behavior. Methods: Analyses included N=255 mother-infant dyads, primarily minorities (21% Blacks; 42% Hispanics), enrolled in an urban pregnancy cohort. Maternal prenatal stress was indexed by a negative life events (NLEs) score on the Crisis in Family Systems-Revised survey. Prenatal total daily intakes of polyunsaturated fatty acids (PUFAs) (n3, n6) were estimated from a food frequency questionnaire; n3:n6 ratios were calculated. Mothers completed the Infant Behavior Questionnaire-Revised (IBQ-R), a measure of infant temperament, when the children were 6 months old. Three commonly used dimensions were derived: Orienting & Regulation, Extraversion, and Negative Affectivity. Associations among prenatal stress, maternal n3:n6 ratio, and race/ethnicity on infant temperament, controlling for maternal education and age and child sex, were examined. Results: Among Blacks, prenatal stress effects on infant Orienting & Regulation scores were modified by maternal n3:n6 ratios (p=0.03): As NLEs increased, lower n3:n6 ratios predicted lower infant Orienting & Regulation scores, whereas higher n3:n6 ratios attenuated the effect of prenatal stress. There were no main or interaction effects predicting Extraversion or Negative Affectivity. Conclusions: An optimal PUFA ratio may protect the fetus from stress effects on infant behavior, particularly among Blacks. These findings may have implications for later neurodevelopment and social functioning predicted by early temperamental characteristics

Vibrationally resolved two-photon electronic spectra including vibrational pre-excitation:Theory and application to VIPER spectroscopy with two-photon excitation

Following up on our previous work on vibrationally resolved electronic absorption spectra including the effect of vibrational pre-excitation [J. von Cosel et al., J. Chem. Phys. 147, 164116 (2017)], we present a combined theoretical and experimental study of two-photon induced vibronic transitions in polyatomic molecules that are probed in the Vibrationally Promoted Electronic Resonance experiment using two-photon excitation (2P-VIPER). In order to compute vibronic spectra, we employ time-independent and time-dependent methods based on the evaluation of Franck-Condon overlap integrals and Fourier transformation of time-domain correlation functions, respectively. The time-independent approach uses a generalized version of the FCclasses method, while the time-dependent approach relies on the analytical evaluation of Gaussian moments within the harmonic approximation including Duschinsky rotation effects. For the Coumarin 6 dye, two-dimensional 2P-VIPER experiments involving excitation to the lowest-lying singlet excited state S1 are presented and compared with corresponding one-photon (1P)-VIPER spectra. In both cases, coumarin ring modes and a CO stretch mode show VIPER activity, albeit with different relative intensities. Selective pre-excitation of these modes leads to a pronounced redshift of the low-frequency edge of the electronic absorption spectrum, which is a prerequisite for the VIPER experiment. Theoretical analysis underscores the role of interference between Franck-Condon and Herzberg-Teller effects in the two-photon experiment, which is at the root of the observed intensity distribution

N-Aryl mercaptoacetamides as potential multi-target inhibitors of metallo-β-lactamases (MBLs) and the virulence factor LasB from Pseudomonas aeruginosa

Increasing antimicrobial resistance is evolving to be one of the major threats to public health. To reduce the selection pressure and thus to avoid a fast development of resistance, novel approaches aim to target bacterial virulence instead of growth. Another strategy is to restore the activity of antibiotics already in clinical use. This can be achieved by the inhibition of resistance factors such as metallo-β-lactamases (MBLs). Since MBLs can cleave almost all β-lactam antibiotics, including the “last resort” carbapenems, their inhibition is of utmost importance. Here, we report on the synthesis and in vitro evaluation of N-aryl mercaptoacetamides as inhibitors of both clinically relevant MBLs and the virulence factor LasB from Pseudomonas aeruginosa. All tested N-aryl mercaptoacetamides showed low micromolar to submicromolar activities on the tested enzymes IMP-7, NDM-1 and VIM-1. The two most promising compounds were further examined in NDM-1 expressing Klebsiella pneumoniae isolates, where they restored the full activity of imipenem. Together with their LasB-inhibitory activity in the micromolar range, this class of compounds can now serve as a starting point for a multi-target inhibitor approach against both bacterial resistance and virulence, which is unprecedented in antibacterial drug discovery

A novel detector system for KATRIN to search for keV-scale sterile neutrinos

International audienceSterile neutrinos appear in minimal extensions of the Standard Model of particle physics. If their mass is in the keV regime, they are viable dark matter candidates. One way to search for sterile neutrinos in a laboratory-based experiment is via the analysis of β-decay spectra, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the β-decay spectrum. The objective of the TRISTAN project is to extend the KATRIN setup with a new multi-pixel silicon drift detector system to search for a keV-scale sterile neutrino signal. In this paper we describe the requirements of such a new detector, and present first characterization measurement results obtained with a 7 pixel prototype system