ALBERT

Description: Author(s): Andreas Albrecht and Martin B. Plenio The impact of control sequences on the environmental coupling of a quantum system can be described in terms of a filter. Here we analyze how the coherent evolution of two interacting spins subject to periodic control pulses, using the example of a nitrogen vacancy center coupled to a nuclear spin, c… [Phys. Rev. A 92, 022340] Published Tue Aug 18, 2015

Description: Author(s): Andreas Albrecht, R. Holman, and Benoit J. Richard Models such as Natural Inflation that use pseudo-Nambu-Goldstone bosons as the inflaton are attractive for many reasons. However, they typically require trans-Planckian field excursions Δ Φ 〉 M Pl , due to the need for an axion decay constant f 〉 M Pl to have both a sufficient number of e -folds and va... [Phys. Rev. Lett. 114, 171301] Published Thu Apr 30, 2015

Description: Author(s): Andreas Albrecht I explore the possibility that the cosmos is fundamentally an equilibrium system and review the attractive features of such theories. Equilibrium cosmologies are commonly thought to fail due to the “Boltzmann brain” problem. I show that it is possible to evade the Boltzmann brain problem if there is... [Phys. Rev. D 91, 103510] Published Wed May 13, 2015

Description: Author(s): Daniel Phillips, Andrew Scacco, and Andreas Albrecht We compare two holographic arguments that impose especially strong bounds on the amount of inflation. One comes from the de Sitter equilibrium cosmology and the other from the work of Banks and Fischler. We find that simple versions of these two approaches yield the same bound on the number of e-fol... [Phys. Rev. D 91, 043513] Published Wed Feb 11, 2015

Description: Author(s): Andreas Albrecht, R. Holman, and Benoit J. Richard We address the following question: To what extent can a quantum field tell if it has been placed in de Sitter space? Our approach is to use the techniques of nonequilibrium quantum field theory to compute the time evolution of a state which starts off in flat space for (conformal) times η〈η 0 and ... [Phys. Rev. D 91, 043517] Published Thu Feb 12, 2015

Description: Author(s): Andrew Scacco and Andreas Albrecht We test a model of inflation with a fast-rolling kinetic-dominated initial condition against data from Planck using Markov chain Monte Carlo parameter estimation. We test both an m 2 ϕ 2 potential and the R + R 2 gravity model and perform a full numerical calculation of both the scalar and tensor primordi… [Phys. Rev. D 92, 083506] Published Tue Oct 06, 2015

Description: Background: Gene expression profiling using high-throughput screening (HTS) technologies allows clinical researchers to find prognosis gene signatures that could better discriminate between different phenotypes and serve as potential biological markers in disease diagnoses. In recent years, many feature selection methods have been devised for finding such discriminative genes, and more recently information theoretic filters have also been introduced for capturing feature-to-class relevance and feature-to-feature correlations in microarray-based classification. Methods: In this paper, we present and fully formulate a new multivariate filter, iRDA, for the discovery of HTS gene-expression candidate genes. The filter constitutes a four-step framework and includes feature relevance, feature redundancy, and feature interdependence in the context of feature-pairs. The method is based upon approximate Markov blankets, information theory, several heuristic search strategies with forward, backward and insertion phases, and the method is aiming at higher order gene interactions. Results: To show the strengths of iRDA, three performance measures, two evaluation schemes, two stability index sets, and the gene set enrichment analysis (GSEA) are all employed in our experimental studies. Its effectiveness has been validated by using seven well-known cancer gene-expression benchmarks and four other disease experiments, including a comparison to three popular information theoretic filters. In terms of classification performance, candidate genes selected by iRDA perform better than the sets discovered by the other three filters. Two stability measures indicate that iRDA is the most robust with the least variance. GSEA shows that iRDA produces more statistically enriched gene sets on five out of the six benchmark datasets. Conclusions: Through the classification performance, the stability performance, and the enrichment analysis, iRDA is a promising filter to find predictive, stable, and enriched gene-expression candidate genes.

Description: Author(s): Daniel Phillips and Andreas Albrecht [Phys. Rev. D 84, 123530] Published Fri Dec 30, 2011

Description: Author(s): Andreas Albrecht, Alex Retzker, and Martin B. Plenio Interferometry with massive particles may have the potential to explore the limitations of standard quantum mechanics, in particular where it concerns its boundary with general relativity and the yet to be developed theory of quantum gravity. This development is hindered considerably by the lack of ... [Phys. Rev. A 90, 033834] Published Mon Sep 22, 2014

Description: Author(s): Andreas Albrecht and Daniel Phillips We argue using simple models that all successful practical uses of probabilities originate in quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus we claim there is no physically verified fully classical theory of probability. We comment on t... [Phys. Rev. D 90, 123514] Published Thu Dec 11, 2014