Addendum: Ultrahigh-energy cosmic-ray bounds on nonbirefringent modified-Maxwell theory

Nonbirefringent modified-Maxwell theory, coupled to standard Dirac particles, involves nine dimensionless parameters, which can be bounded by the inferred absence of vacuum Cherenkov radiation for ultrahigh-energy cosmic rays (UHECRs). With selected UHECR events, two-sided bounds on the eight nonisotropic parameters are obtained at the 10^{-18} level, together with an improved one-sided bound on the single isotropic parameter at the 10^{-19} level.Comment: 5 pages with revtex

iCrawl: Improving the Freshness of Web Collections by Integrating Social Web and Focused Web Crawling

Researchers in the Digital Humanities and journalists need to monitor, collect and analyze fresh online content regarding current events such as the Ebola outbreak or the Ukraine crisis on demand. However, existing focused crawling approaches only consider topical aspects while ignoring temporal aspects and therefore cannot achieve thematically coherent and fresh Web collections. Especially Social Media provide a rich source of fresh content, which is not used by state-of-the-art focused crawlers. In this paper we address the issues of enabling the collection of fresh and relevant Web and Social Web content for a topic of interest through seamless integration of Web and Social Media in a novel integrated focused crawler. The crawler collects Web and Social Media content in a single system and exploits the stream of fresh Social Media content for guiding the crawler.Comment: Published in the Proceedings of the 15th ACM/IEEE-CS Joint Conference on Digital Libraries 201

Defects of thin CaO(001) on Mo(001): an EPR spectroscopic perspective

Paramagnetic defects of thin CaO(001) films grown on Mo(001) are characterized using electron paramagnetic resonance (EPR) spectroscopy under ultrahigh vacuum conditions. A variety of paramagnetic centers located in the volume of the films are identified whose speciation as well as relative abundance was found to depend on the growth rate of the films. Pristine films prepared at a lower growth rate exhibited a larger number and a different speciation of paramagnetic defects than films grown at a higher rate. Annealing of the films to 1030 K, which improves their long-range order, results in quenching of most of the paramagnetic species observed for the pristine film; however, films prepared at a lower growth rate exhibit new paramagnetic signals upon annealing, which are absent in films prepared at a higher growth rate. The signals can be assigned to paramagnetic Mo ions previously shown to diffuse into these films. These results indicate that the amount and speciation of the transition metal ions depend on the preparation conditions which in turn can also affect the surface chemistry of these systems

Improved model for the analysis of air fluorescence induced by electrons

A model recently proposed for the calculation of air-fluorescence yield excited by electrons is revisited. Improved energy distributions of secondary electrons and a more realistic Monte Carlo simulation including some additional processes have allowed us to obtain more accurate results. The model is used to study in detail the relationship between fluorescence intensity and deposited energy in a wide range of primary energy (keVs - GeVs). In addition, predictions on the absolute value of the fluorescence efficiency in the absence of collisional quenching will be presented and compared with available experimental data.Comment: Contribution to the 5th Fluorescence Workshop, El Escorial, Madrid, Spain, September 2007, to appear in Nuclear Instruments and Methods A. Revised version.- More details on the comparison with experimental dat

Exponential Resolution Lower Bounds for Weak Pigeonhole Principle and Perfect Matching Formulas over Sparse Graphs

We show exponential lower bounds on resolution proof length for pigeonhole principle (PHP) formulas and perfect matching formulas over highly unbalanced, sparse expander graphs, thus answering the challenge to establish strong lower bounds in the regime between balanced constant-degree expanders as in [Ben-Sasson and Wigderson '01] and highly unbalanced, dense graphs as in [Raz '04] and [Razborov '03, '04]. We obtain our results by revisiting Razborov's pseudo-width method for PHP formulas over dense graphs and extending it to sparse graphs. This further demonstrates the power of the pseudo-width method, and we believe it could potentially be useful for attacking also other longstanding open problems for resolution and other proof systems

Access to N-alkylated amino acids by microbial fermentation

N-methylated amino acids are found in many pharmaceutically active compounds and have been shown to improve pharmacokinetic properties as constituents of peptide drugs since N-methylation of amino acids may result in conformational changes, improved proteolytic stability and higher lipophilicity of the peptide drug.1 N-methylated amino acids are mainly produced chemically or by biocatalysis, however with low yields or high costs for co-factor regeneration. First, we established a fermentative route for production of N-mehtyl-L-glutamate by Pseudomonas putida from glucose and glycerol. Interception of the C1 assimilation pathway of Methylobacterium extorquence yielded N-methyl-L-glutamate titers of 17.9 g L-1 in fed-batch cultivation.2 Due to high substrate specificity of this C1 assimilation pathway genes, we continued with an independent pathway for extension of the product range. Therefore, we focus on pathway-design for N-methylated amino acids by the industrially relevant production host Corynebacterium glutamicum. Metabolic engineering of C. glutamicum led to an expanded product range of proteinogenic amino acids like L-valine2 but also ω-amino acids like γ-aminobutyrate and diamines like putrescine3. The rare imine reductase DpkA from P. putida KT2440 catalyzes the reductive methylamination of pyruvate as side activity. Implementation of DpkA into the central carbon metabolism of the pyruvate overproducing C. glutamicum strain ELB-P4 yielded N-methyl-L-alanine production. Optimization of carbon- and nitrogen ratios of the minimal medium allowed production of up to 10.5 g L-1 when cultivated in shake flasks. N-methyl-L-alanine titers of 31.7 g L-1 with a yield of 0.71 g per g glucose were achieved in fed-batch cultivation5. Due to the somewhat relaxed substrate scope of DpkA, the product portfolio of N-methylated amino acids produced by fermentation could be successfully extended. Changing the base strain to a glyoxylate producing C. glutamicum strain6 achieved production of 2.6 g L-1 sarcosine, the N-methylated glycine derivative, from glucose. Sarcosine production based on the second generation feedstocks xylose and arabinose led to higher product titers than glucose-based production and optimization of substrate composition led to a titer of 8.7 g L-1 sarcosine. This is the first example in which a C. glutamicum process using lignocellulosic pentoses is superior to glucose-based production. By mutation of the active site of DpkA, a mutant with higher specific activity towards glyoxylate (30.3 ± 2.7 U mg-1; wild type enzyme 25.7 ± 1.8 U mg-1) was identified. Therefore, the mutant DpkAF117L was incorporated into the production strain and enabled faster sarcosine production. Additionally, this mutation led to an increased activity towards reductive ethylamination of glyoxylate (31.2 ± 1.1 U mg-1; wild type enzyme 25.3 ± 3.2 U mg-1). As a result, the fermentative production of N-ethylglycine showed enhanced volumetric productivity compared to the strain harboring the wild type enzyme. Fermentative access to N-methylated amino acids was achieved by two independent pathway designs. First, we enabled N-methyl-L-glutamate production by pathway interception in P. putida. Additionally, introduction of the imine reductase gene dpkA from P. putida into various 2-oxoacid producing C. glutamicum strains extended the product range. Optimization of medium composition, preferred substrate specificity of the strain or the enzyme itself resulted in excellent production yields. 1 Chatterjee J, Rechenmacher F and Kesser H, Angew. Chem. Int. Ed., 2013, 52, 254-269. 2 Mindt M, Walter T, Risser JM and Wendisch VF, Front. Bioeng. Biotechnol., 2018, 6, 159. 3 Wendisch VF, Mindt M and Pérez-García F, Appl. Microbiol. Biotechnol., 2018, 102, 3583-3594. 4 Wieschalka S, Blombach B and Eikmanns BJ, Appl. Microbiol. Biotechnol., 2012, 94, 449-459. 5 Mindt M, Risse JM, Gruß H, Sewald N, Eikmanns BJ and Wendisch VF, Sci. Rep., 2018, 8, 12895. 6 Zahoor A, Otten A and Wendisch VF, J. Biotechnol., 2014, 192, 366-37

Comparison between methods for the determination of the primary cosmic ray mass composition from the longitudinal profile of atmospheric cascades

The determination of the primary cosmic ray mass composition from the longitudinal development of atmospheric cascades is still a debated issue. In this work we discuss several data analysis methods and show that if the entire information contained in the longitudinal profile is exploited, reliable results may be obtained. Among the proposed methods FCC ('Fit of the Cascade Curve'), MTA ('Multiparametric Topological Analysis') and NNA ('Neural Net Analysis') with conjugate gradient optimization algorithm give the best accuracy.Comment: 22 pages, 11 figures, accepted by Astroparticle Physics, minor misprints and an extra figure remove

The politics of international redistribution: Explaining public support for fiscal transfers in the EU

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.As a consequence of the Eurozone crisis and the creation of the European Stability Mechanism (ESM), the prospect of a transfer union has become a particularly contested aspect of European integration. How should one understand the public backlash against fiscal transfers? And, what explains voter preferences for international transfers more generally? Using data from the 2014 European Elections Study (EES), this article describes the first cross-national analysis of voters’ preferences on international transfers. The analysis reveals a strong association between voters’ non-economic cultural orientations (i.e., their cosmopolitanism) and their position on transfers. At the same time, it is found that voters’ economic left-right orientations are crucial for a fuller understanding of the public conflict over transfers. This counters previous research that finds economic left-right orientations to be of little explanatory value. This study demonstrates that the association between economic left-right orientations and preferences for international transfers is conditional on a person's social class. Among citizens in a high-income class an economically left-leaning position is associated with support for transfers, whereas it is associated with opposition to transfers among citizens in a low-income class