Natural modes of Bernoulli-Euler beams with a single-edge crack

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76643/1/AIAA-1990-1124-836.pd

The Belgian repository of fundamental atomic data and stellar spectra (BRASS). I. Cross-matching atomic databases of astrophysical interest

Fundamental atomic parameters, such as oscillator strengths, play a key role in modelling and understanding the chemical composition of stars in the universe. Despite the significant work underway to produce these parameters for many astrophysically important ions, uncertainties in these parameters remain large and can propagate throughout the entire field of astronomy. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide the largest systematic and homogeneous quality assessment of atomic data to date in terms of wavelength, atomic and stellar parameter coverage. To prepare for it, we first compiled multiple literature occurrences of many individual atomic transitions, from several atomic databases of astrophysical interest, and assessed their agreement. Several atomic repositories were searched and their data retrieved and formatted in a consistent manner. Data entries from all repositories were cross-matched against our initial BRASS atomic line list to find multiple occurrences of the same transition. Where possible we used a non-parametric cross-match depending only on electronic configurations and total angular momentum values. We also checked for duplicate entries of the same physical transition, within each retrieved repository, using the non-parametric cross-match. We report the cross-matched transitions for each repository and compare their fundamental atomic parameters. We find differences in log(gf) values of up to 2 dex or more. We also find and report that ~2% of our line list and Vienna Atomic Line Database retrievals are composed of duplicate transitions. Finally we provide a number of examples of atomic spectral lines with different log(gf) values, and discuss the impact of these uncertain log(gf) values on quantitative spectroscopy. All cross-matched atomic data and duplicate transitions are available to download at brass.sdf.org.Comment: 18 pages, 12 figures, 9 tables. Accepted for publication in A&

Simple Sequence Repeats and Mucoid Conversion: Biased mucA Mutagenesis in Mismatch Repair-Deficient Pseudomonas aeruginosa

In Pseudomonas aeruginosa, conversion to the mucoid phenotype marks the onset of an irreversible state of the infection in Cystic Fibrosis (CF) patients. The main pathway for mucoid conversion is mutagenesis of the mucA gene, frequently due to −1 bp deletions in a simple sequence repeat (SSR) of 5 Gs (G5-SSR426). We have recently observed that this mucA mutation is particularly accentuated in Mismatch Repair System (MRS)-deficient cells grown in vitro. Interestingly, previous reports have shown a high prevalence of hypermutable MRS-deficient strains occurring naturally in CF chronic lung infections. Here, we used mucA as a forward mutation model to systematically evaluate the role of G5-SSR426 in conversion to mucoidy in a MRS-deficient background, with this being the first analysis combining SSR-dependent localized hypermutability and the acquisition of a particular virulence/persistence trait in P. aeruginosa. In this study, mucA alleles were engineered with different contents of G:C SSRs, and tested for their effect on the mucoid conversion frequency and mucA mutational spectra in a mutS-deficient strain of P. aeruginosa. Importantly, deletion of G5-SSR426 severely reduced the emergence frequency of mucoid variants, with no preferential site of mutagenesis within mucA. Moreover, although mutagenesis in mucA was not totally removed, this was no longer the main pathway for mucoid conversion, suggesting that G5-SSR426 biased mutations towards mucA. Mutagenesis in mucA was restored by the addition of a new SSR (C6-SSR431), and even synergistically increased when G5-SSR426 and C6-SSR431 were present simultaneously, with the mucA mutations being restricted to −1 bp deletions within any of both G:C SSRs. These results confirm a critical role for G5-SSR426 enhancing the mutagenic process of mucA in MRS-deficient cells, and shed light on another mechanism, the SSR- localized hypermutability, contributing to mucoid conversion in P. aeruginosa

Shifting gas-to-liquid partitioning coefficient of odorous compounds to liquid in biotechniques using additives

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