Wolfgang Wagner

Bio: Wolfgang Wagner is an academic researcher from Vienna University of Technology. The author has contributed to research in topics: Large Hadron Collider & Top quark. The author has an hindex of 156, co-authored 2342 publications receiving 123391 citations. Previous affiliations of Wolfgang Wagner include University of Pennsylvania & University of Amsterdam.

Monte carlo evaluation of functionals of solutions of stochastic differential equations. variance reduction and numerical examples

Abstract: Variance–reducing estimators are derived for functionals of the solution of the general Ito stochastic differential equation. These estimators allow to apply variance reduction techniques known from the Monte Carlo theory. In particular, variance–reducing Euler estimators are constructed as well as variance–reducing unbiased estimators. Numerical examples are given. They show that the variance reduction techniques cause an enormous gain in efficiency, reducing the statistical error up to 50 times. They also demonstrate the effect of the unbiased estimators, which allow to evaluate the functionals without reducing the time step.

Liberal Power Europe

Abstract: The European Union is best understood as a liberal power – as an actor that is composed of liberal democracies whose interests, identities and institutions motivate and constrain its policy. The conceptualization of the EU as a liberal power helps to overcome three shortcomings of alternative notions such as civilian power or Normative Power Europe: First, norms are not only understood as driving forces but also as constraints on foreign policy; second, liberal power Europe emphasizes the contested nature of norms and conflicts between norms and thus draws attention to the politics of EU external relations; third, it encourages an engagement with the vast literature on the distinctive policies of liberal democracies in international relations and foreign policy analysis. The EU’s crisis management serves to illustrate the value-added of the liberal power Europe concept.

Measurement of jet fragmentation in Pb+Pb and pp collisions at √sNN=5.02 TeV with the ATLAS detector

Abstract: This paper presents a measurement of jet fragmentation functions in 0.49 nb−1 of Pb+Pb collisions and 25 pb−1 of pp collisions at √sNN=5.02 TeV collected in 2015 with the ATLAS detector at the LHC. These measurements provide insight into the jet quenching process in the quark-gluon plasma created in the aftermath of ultrarelativistic collisions between two nuclei. The modifications to the jet fragmentation functions are quantified by dividing the measurements in Pb+Pb collisions by baseline measurements in pp collisions. This ratio is studied as a function of the transverse momentum of the jet, the jet rapidity, and the centrality of the collision. In both collision systems, the jet fragmentation functions are measured for jets with transverse momentum between 126 and 398 GeV and with an absolute value of jet rapidity less than 2.1. An enhancement of particles carrying a small fraction of the jet momentum is observed, which increases with centrality and with increasing jet transverse momentum. Yields of particles carrying a very large fraction of the jet momentum are also observed to be enhanced. Between these two enhancements of the fragmentation functions a suppression of particles carrying an intermediate fraction of the jet momentum is observed in Pb+Pb collisions. A small dependence of the modifications on jet rapidity is observed.

Performance of the missing transverse momentum triggers for the ATLAS detector during Run-2 data taking

Abstract: The factor of four increase in the LHC luminosity, from 0.5 × 1034 cm−2s−1 to 2.0 × 1034cm−2s−1, and the corresponding increase in pile-up collisions during the 2015–2018 data-taking period, presented a challenge for the ATLAS trigger, particularly for those algorithms that select events with missing transverse momentum. The output data rate at fixed threshold typically increases exponentially with the number of pile-up collisions, so the legacy algorithms from previous LHC data-taking periods had to be tuned and new approaches developed to maintain the high trigger efficiency achieved in earlier operations. A study of the trigger performance and comparisons with simulations show that these changes resulted in event selection efficiencies of > 98% for this period, meeting and in some cases exceeding the performance of similar triggers in earlier run periods, while at the same time keeping the necessary bandwidth within acceptable limits.

Can representations explain social behaviour? a discussion of social representations as rational systems *

Abstract: Two propositions are presented in order to show that social representations cannot be regarded as explanations of behaviour: First it is argued that rational beliefs, decisions, and acting necessarily involve socially constructed knowledge which gains its evidence by collective consensus. Social Representations are considered as one form of collectively validated rational knowledge. Second it is shown that social psychological theories containing common-sense or everyday-rational knowl- edge cannot be interpreted as explanatory theories in the strict sense of the term. Additionally, experi- ments aimed at empirically proving hypotheses deduced from such theories are not a proof, but an "illustration" or "example" of the rational context. Taken together the two propositions lead to the conclusion that rational beliefs and rational behaviour are inseparable from each other, such that a specific belief cannot be used as an explanation of subsequent related behaviour. Equally, social repre- sentations do not explain, but describe related behaviour. One of the logical and methodological problems inherent in social representation theory is the relationship between representation and social behaviour. Usually social representations have been considered as being closely linked to behaviour (e.g. Jodelet, 1984, 1989). This link must be qualified in at least two ways. First, social representations do not account for the behaviour of individuals per se, but only for the behaviour of individuals qua members of social groups (Moscovici, 1982, p. 129). This characteristic is a consequence of their genesis in social discourse. Their socio-genesis of being collectively elaborated implies that social representations be valid systems of knowledge for groups as a whole and the respective group members. Second, social representations are not conceived as cognitions simply inter- vening between stimulus and behavioural response, but as symbolic structures comprising stimulus and behaviour in a simultaneous circular movement. As such, Moscovici (1984, p. 60f) holds, representations do not mediate stimuli but they are stimuli themselves and there- fore independent variables in empirical investigations, be they laboratory or field studies. The status of representations as independent variables makes them a prime candidate to explain collective behaviour on a group level or the behaviour of individuals qua representa- tives of social groups in research (e.g. Echebarria & Gonzales, 1992; Thommen et al., 1988; von Cranach, 1992, etc.). The use of representations as explanatory devices for subsequent behaviour, however, raises crucial epistemological questions. This understanding essentially implies a kind of "causal" link between representation and behaviour. This causal link then is explored in experimental or field studies showing that representation R precedes (the weak version) or causes (the strong version) subsequent behaviour B.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。