Quantum Gravity and Non-unitarity in Black Hole Evaporation

We discuss the relevance of quantum gravitational corrections to the functional Schr\"odinger equation for the information loss paradox in black hole evaporation. These corrections are found from the Wheeler-DeWitt equation through a semiclassical expansion scheme. The dominant contribution in the final evaporation stage, when the black hole approaches the Planck regime, is a term which explicitly violates unitarity in the non-gravitational sector. While pure states remain pure, there is an increase in the degree of purity for non-pure states in this sector. This result holds irrespective of whether full quantum gravity respects unitarity or not.Comment: 6 pages, Latex, ZU-TH 25/9

Fluorescence-based monitoring of ribosome assembly landscapes

Background Ribosomes and functional complexes of them have been analyzed at the atomic level. Far less is known about the dynamic assembly and degradation events that define the half-life of ribosomes and guarantee their quality control. Results We developed a system that allows visualization of intact ribosomal subunits and assembly intermediates (i.e. assembly landscapes) by convenient fluorescence-based analysis. To this end, we labeled the early assembly ribosomal proteins L1 and S15 with the fluorescent proteins mAzami green and mCherry, respectively, using chromosomal gene insertion. The reporter strain harbors fluorescently labeled ribosomal subunits that operate wild type-like, as shown by biochemical and growth assays. Using genetic and chemical perturbations by depleting genes encoding the ribosomal proteins L3 and S17, respectively, or using ribosome-targeting antibiotics, we provoked ribosomal subunit assembly defects. These defects were readily identified by fluorometric analysis after sucrose density centrifugation in unprecedented resolution. Conclusion This strategy is useful to monitor and characterize subunit specific assembly defects caused by ribosome-targeting drugs that are currently used and to characterize new molecules that affect ribosome assembly and thereby constitute new classes of antibacterial agents

Formalization model of expert knowledge about a technical index level of engineering products

The authors set a timely problem that concerns development of decision making models, which allow formalizing expert subjective ideas about technical index level of engineering products. The authors proposed a formalization model of expert knowledge about technical index level of engineering products on the basis of fuzzy sets. The model has a method of membership-function construction for linguistic variable terms on the basis of exponential functions

A detailed description of two controlled experiments concerning the usefulness of assertions as a means for programming

Assertions or more generally "Programming by contract" have gained widespread acceptance in the computer science community as a means for correct program development. However, the literature lacks an empirically evaluation of the benefits a programmer gains by using assertions in his software development. This paper reports about two controlled experiments to close this gap. Both experiments compared "Programming by contract" to the traditional programming style without assertions. The evaluation suggests that assertions tend to decrease the programming effort and that assertions lead to more reliable programs compared to those programs written without using them

On Modeling IND-CCA Security in Cryptographic Protocols

Two common notions of security for public key encryption schemes are shown to be equivalent: we prove that indistinguishability against chosen-ciphertext attacks (IND-CCA) is in fact polynomially equivalent to (yet slightly weaker than) securely realizing the ideal functionality F_PKE in the general modeling of cryptographic protocols of [http://eprint.iacr.org/2000/067]. This disproves in particular the claim that security in the sense of IND-CCA strictly implies security in the sense of realizing F_PKE (see [http://eprint.iacr.org/2000/067]). Moreover, we give concrete reductions among such security notions and show that these relations hold for both uniform and non-uniform adversarial entities

Field validation of a novel passive sampler for dissolved PFAS in surface waters

Numerous per- and polyfluoroalkyl substances (PFAS) are of growing concern worldwide due to their ubiquitous presence, bioaccumulation and adverse effects. Surface waters in the United States have displayed elevated concentrations of PFAS, but so far discrete water sampling has been the commonly applied sampling approach. In the present study we field-tested a novel integrative passive sampler, a microporous polyethylene tube, and derived sampling rates (Rs) for nine PFAS in surface waters. Three sampling campaigns were conducted, deploying polyethylene tube passive samplers in the effluent of two wastewater treatment plant (WWTP) effluents and across Narragansett Bay (Rhode Island, USA) for 1 month each in 2017 and 2018. Passive samplers exhibited linear uptake of PFAS in the WWTP effluents over 16–29 days, with in situ Rs for nine PFAS ranging from 10 ml day−1 (perfluoropentanoic acid) to 29 ml day−1 (perfluorooctanesulfonic acid). Similar sampling rates of 19 ± 4.8 ml day−1 were observed in estuarine field deployments. Applying these Rs values in a different WWTP effluent predicted dissolved PFAS concentrations mostly within 50% of their observations in daily composite water samples, except for perfluorobutanoic acid (where predictions from passive samplers were 3 times greater than measured values), perfluorononanoic acid (1.9 times), perfluorodecanoic acid (1.7 times), and perfluoropentanesulfonic acid (0.1 times). These results highlight the potential use of passive samplers as measurement and assessment tools of PFAS in dynamic aquatic environments