Microstructure evolution, texture development, and mechanical properties of hot-rolled 5052 aluminum alloy followed by annealing

Aluminum alloys, especially the 5000 series, have drawn the attention of the transportation industry due to their lightweight and consequently reduced fuel consumption. In this regard, one of the major problems of this alloy is its low strength and ductility that can be solved using rolling and post-annealing. Accordingly, the present study concentrates on this issue. Microstructural images showed that the rolling process develops a lot of tangled and trapped dislocations in the sample, which gradually lead to the formation of dislocation bundles and networks. Subsequent annealing can produce a more homogeneous structure with clear grain boundaries and low dislocation density in the inner region of the grains. However, grain refinement efficiency through rolling is retained even after annealing. Initial and rolled Al5052 with the maximum intensity of 2.87 and 6.33 possess the lowest and highest overall texture. Also, post-annealing decreases the texture intensity to 6.33 and 4.87 at 150 and 200 °C, respectively. In this context, deformation texture components strengthen considerably after the rolling process due to the formation of shear bands, and they slightly weaken during heat treatment. Although the initial annealing of the as-received material does not cause discontinuous recrystallization during rolling, it may facilitate the material recovery before rolling. Post-annealing was found to decrease the improved effect of strength by rolling and increase the negative influence of ductility due to the inhibition of dislocation strengthening. The results showed that both dislocation density and the precipitation of Mg atoms are influential for electrical resistivity

Primary and Secondary Sequence Structure Requirements for Recognition and Discrimination of Target RNAs by Pseudomonas aeruginosa RsmA and RsmF

ABSTRACT CsrA family RNA-binding proteins are widely distributed in bacteria and regulate gene expression at the posttranscriptional level. Pseudomonas aeruginosa has a canonical member of the CsrA family (RsmA) and a novel, structurally distinct variant (RsmF). To better understand RsmF binding properties, we performed parallel systematic evolution of ligands by exponential enrichment (SELEX) experiments for RsmA and RsmF. The initial target library consisted of 62-nucleotide (nt) RNA transcripts with central cores randomized at 15 sequential positions. Most targets selected by RsmA and RsmF were the expected size and shared a common consensus sequence (CANGGAYG) that was positioned in a hexaloop region of the stem-loop structure. RsmA and RsmF also selected for longer targets (≥96 nt) that were likely generated by rare PCR errors. Most of the long targets contained two consensus-binding sites. Representative short (single consensus site) and long (two consensus sites) targets were tested for RsmA and RsmF binding. Whereas RsmA bound the short targets with high affinity, RsmF was unable to bind the same targets. RsmA and RsmF both bound the long targets. Mutation of either consensus GGA site in the long targets reduced or eliminated RsmF binding, suggesting a requirement for two tandem binding sites. Conversely, RsmA bound long targets containing only a single GGA site with unaltered affinity. The RsmF requirement for two binding sites was confirmed with tssA1 , an in vivo regulatory target of RsmA and RsmF. Our findings suggest that RsmF binding requires two GGA-containing sites, while RsmA binding requirements are less stringent. IMPORTANCE The CsrA family of RNA-binding proteins is widely conserved in bacteria and plays important roles in the posttranscriptional regulation of protein synthesis. P. aeruginosa has two CsrA proteins, RsmA and RsmF. Although RsmA and RsmF share a few RNA targets, RsmF is unable to bind to other targets recognized by RsmA. The goal of the present study was to better understand the basis for differential binding by RsmF. Our data indicate that RsmF binding requires target RNAs with two consensus-binding sites, while RsmA recognizes targets with just a single binding site. This information should prove useful to future efforts to define the RsmF regulon and its contribution to P. aeruginosa physiology and virulence

An unusual CsrA family member operates in series with RsmA to amplify posttranscriptional responses in Pseudomonas aeruginosa

Members of the CsrA family of prokaryotic mRNA-binding proteins alter the translation and/or stability of transcripts needed for numerous global physiological processes. The previously described CsrA family member in Pseudomonas aeruginosa (RsmA) plays a central role in determining infection modality by reciprocally regulating processes associated with acute (type III secretion and motility) and chronic (type VI secretion and biofilm formation) infection. Here we describe a second, structurally distinct RsmA homolog in P. aeruginosa (RsmF) that has an overlapping yet unique regulatory role. RsmF deviates from the canonical 5 β-strand and carboxyl-terminal α-helix topology of all other CsrA proteins by having the α-helix internally positioned. Despite striking changes in topology, RsmF adopts a tertiary structure similar to other CsrA family members and binds a subset of RsmA mRNA targets, suggesting that RsmF activity is mediated through a conserved mechanism of RNA recognition. Whereas deletion of rsmF alone had little effect on RsmA-regulated processes, strains lacking both rsmA and rsmF exhibited enhanced RsmA phenotypes for markers of both type III and type VI secretion systems. In addition, simultaneous deletion of rsmA and rsmF resulted in superior biofilm formation relative to the wild-type or rsmA strains. We show that RsmF translation is derepressed in an rsmA mutant and demonstrate that RsmA specifically binds to rsmF mRNA in vitro, creating a global hierarchical regulatory cascade that operates at the posttranscriptional level

Terminal valuations, growth rates and the implied cost of capital

This article is published with open access at Springerlink.comWe develop a model based on the notion that prices lead earnings, allowing for a simultaneous estimation of the implied growth rate and the cost of equity capital for US industrial sectors. The major difference between our approach and that in prior literature is that ours avoids the necessity to make assumptions about terminal values and consequently about future growth rates. In fact, growth rates are an endogenous variable, which is estimated simultaneously with the implied cost of equity capital. Since we require only 1-year-ahead forecasts of earnings and no assumptions about dividend payouts, our methodology allows us to estimate ex ante aggregate growth and risk premia over a larger sample of firms than has previously been possible. Our estimate of the risk premium being between 3.1 and 3.9 % is at the lower end of recent estimates, reflecting the inclusion of these short-lived companies. Our estimate of the long run growth is from 4.2 to 4.7 %

The Simplicity of Optimal Trading in Order Book Markets

A trader’s execution strategy has a large effect on his profits. Identifying an optimal strategy, however, is often frustrated by the complexity of market microstructures. We analyse an order book based on continuous double auction market under two different models of trader’s behaviour. In the first case actions only depend on a linear combination of the best bid and ask. In the second model, traders adopt the Markov perfect equilibrium strategies of the trading game. Both models are analytically intractable, and so optimal strategies are identified by the use of numerical techniques. Using the Markov model we show that, beyond the best quotes, additional information has little effect on either the behaviour of traders or the dynamics of the market. The remarkable similarity of the results obtained by the linear model indicates that the optimal strategy may be reasonably approximated by a linear function. We conclude that while the order book market and strategy space of traders are potentially very large and complex, optimal strategies may be relatively simple and based on a minimal information set

The Hot (Invisible?) Hand: Can Time Sequence Patterns of Success/Failure in Sports Be Modeled as Repeated Random Independent Trials?

The long lasting debate initiated by Gilovich, Vallone and Tversky in is revisited: does a “hot hand” phenomenon exist in sports? Hereby we come back to one of the cases analyzed by the original study, but with a much larger data set: all free throws taken during five regular seasons () of the National Basketball Association (NBA). Evidence supporting the existence of the “hot hand” phenomenon is provided. However, while statistical traces of this phenomenon are observed in the data, an open question still remains: are these non random patterns a result of “success breeds success” and “failure breeds failure” mechanisms or simply “better” and “worse” periods? Although free throws data is not adequate to answer this question in a definite way, we speculate based on it, that the latter is the dominant cause behind the appearance of the “hot hand” phenomenon in the data

Auctions with Endogenous Price Ceiling: Theoretical and Experimental Results

This paper analyzes an auction mechanism that excludes overoptimistic bidders inspired by the rules of the procurement auctions adopted by several Japanese local governments. Our theoretical and experimental results suggest that the endogenous exclusion rule reduces the probability of suffering a monetary loss induced by winning the auction, and also mitigates the problem of the winner's curse in the laboratory. However, this protection comes at the price of a lower revenue for the seller

Challenging the heterogeneity of disease presentation in malignant melanoma-impact on patient treatment

There is an increasing global interest to support research areas that can assist in understanding disease and improving patient care. The National Cancer Institute (NIH) has identified precision medicine-based approaches as key research strategies to expedite advances in cancer research. The Cancer Moonshot program ( https://www.cancer.gov/research/key-initiatives/moonshot-cancer-initiative ) is the largest cancer program of all time, and has been launched to accelerate cancer research that aims to increase the availability of therapies to more patients and, ultimately, to eradicate cancer. Mass spectrometry-based proteomics has been extensively used to study the molecular mechanisms of cancer, to define molecular subtypes of tumors, to map cancer-associated protein interaction networks and post-translational modifications, and to aid in the development of new therapeutics and new diagnostic and prognostic tests. To establish the basis for our melanoma studies, we have established the Southern Sweden Malignant Melanoma Biobank. Tissues collected over many years have been accurately characterized with respect to the tumor and patient information. The extreme variability displayed in the protein profiles and the detection of missense mutations has confirmed the complexity and heterogeneity of the disease. It is envisaged that the combined analysis of clinical, histological, and proteomic data will provide patients with a more personalized medical treatment. With respect to disease presentation, targeted treatment and medical mass spectrometry analysis and imaging, this overview report will outline and summarize the current achievements and status within malignant melanoma. We present data generated by our cancer research center in Lund, Sweden, where we have built extensive capabilities in biobanking, proteogenomics, and patient treatments over an extensive time period