Model B4 : multi-decade creep and shrinkage prediction of traditional and modern concretes

To improve the sustainability of concrete infrastructure, engineers face the challenge of incorporating new concrete materials while pushing the expected design life beyond 100 years. The time-dependent creep and shrinkage response of concrete governs the serviceability and durability in this multi-decade time frame. It has been shown that current prediction equations for creep and shrinkage underestimate material deformations observed in structures outside of a laboratory environment. A new prediction model for creep and shrinkage is presented that can overcome some of the shortcomings of the current equations. The model represents an extension and systematic recalibration of model B3, a 1995 RILEM Recommendation, which derives its functional form from the phenomena of diffusion, chemical hydration, moisture sorption, and the evolution of micro-stresses in the cement structure. The model is calibrated through a joint optimization of a new enlarged laboratory test database and a new database of bridge deflection records to overcome the bias towards short-term behavior. A framework for considering effects of aggregates, admixtures, additives, and higher temperatures is also incorporated

Identification of chromosomal alpha-proteobacterial small RNAs by comparative genome analysis and detection in Sinorhizobium meliloti strain 1021

<p>Abstract</p> <p>Background</p> <p>Small untranslated RNAs (sRNAs) seem to be far more abundant than previously believed. The number of sRNAs confirmed in <it>E. coli </it>through various approaches is above 70, with several hundred more sRNA candidate genes under biological validation. Although the total number of sRNAs in any one species is still unclear, their importance in cellular processes has been established. However, unlike protein genes, no simple feature enables the prediction of the location of the corresponding sequences in genomes. Several approaches, of variable usefulness, to identify genomic sequences encoding sRNA have been described in recent years.</p> <p>Results</p> <p>We used a combination of <it>in silico </it>comparative genomics and microarray-based transcriptional profiling. This approach to screening identified ~60 intergenic regions conserved between <it>Sinorhizobium meliloti </it>and related members of the alpha-proteobacteria sub-group 2. Of these, 14 appear to correspond to novel non-coding sRNAs and three are putative peptide-coding or 5' UTR RNAs (ORF smaller than 100 aa). The expression of each of these new small RNA genes was confirmed by Northern blot hybridization.</p> <p>Conclusion</p> <p>Small non coding RNA (<it>sra</it>) genes can be found in the intergenic regions of alpha-proteobacteria genomes. Some of these <it>sra </it>genes are only present in <it>S. meliloti</it>, sometimes in genomic islands; homologues of others are present in related genomes including those of the pathogens <it>Brucella </it>and <it>Agrobacterium</it>.</p

Distinct Chemotaxis Protein Paralogs Assemble into Chemoreceptor Signaling Arrays To Coordinate Signaling Output

Most chemotactic motile bacteria possess multiple chemotaxis signaling systems, the functions of which are not well characterized. Chemotaxis signaling is initiated by chemoreceptors that assemble as large arrays, together with chemotaxis coupling proteins (CheW) and histidine kinase proteins (CheA), which form a baseplate with the cytoplasmic tips of receptors. These cell pole-localized arrays mediate sensing, signaling, and signal amplification during chemotaxis responses. Membrane-bound chemoreceptors with different cytoplasmic domain lengths segregate into distinct arrays. Here, we show that a bacterium, Azospirillum brasilense, which utilizes two chemotaxis signaling systems controlling distinct motility parameters, coordinates its chemotactic responses through the production of two separate membrane-bound chemoreceptor arrays by mixing paralogs within chemotaxis baseplates. The polar localization of chemoreceptors of different length classes is maintained in strains that had baseplate signaling proteins from either chemotaxis system but was lost when both systems were deleted. Chemotaxis proteins (CheA and CheW) from each of the chemotaxis signaling systems (Che1 and Che4) could physically interact with one another, and chemoreceptors from both classes present in A. brasilense could interact with Che1 and Che4 proteins. The assembly of paralogs from distinct chemotaxis pathways into baseplates provides a straightforward mechanism for coordinating signaling from distinct pathways, which we predict is not unique to this system given the propensity of chemotaxis systems for horizontal gene transfer

Inheritance, Biochemical Abnormalities, and Clinical Features of Feline Mucolipidosis II: The First Animal Model of Human I-Cell Disease

Mucolipidosis II (ML II), also called I-cell disease, is a unique lysosomal storage disease caused by deficient activity of the enzyme N-acetylglucosamine-1-phosphotransferase, which leads to a failure to internalize enzymes into lysosomes. We report on a colony of domestic shorthair cats with ML II that was established from a half-sibling male of an affected cat. Ten male and 9 female kittens out of 89 kittens in 26 litters born to clinically normal parents were affected; this is consistent with an autosomal recessive mode of inheritance. The activities of three lysosomal enzymes from affected kittens, compared to normal adult control cats, were high in serum (11-73 times normal) but low in cultured fibroblasts (9-56% of normal range) that contained inclusion bodies (I-cells), reflecting the unique enzyme defect in ML II. Serum lysosomal enzyme activities of adult obligate carriers were intermediate between normal and affected values. Clinical features in affected kittens were observed from birth and included failure to thrive, behavioral dullness, facial dysmorphia, and ataxia. Radiographic lesions included metaphyseal flaring, radial bowing, joint laxity, and vertebral fusion. In contrast to human ML II, diffuse retinal degeneration leading to blindness by 4 months of age was seen in affected kittens. All clinical signs were progressive and euthanasia or death invariably occurred within the first few days to 7 months of life, often due to upper respiratory disease or cardiac failure. The clinical and radiographic features, lysosomal enzyme activities, and mode of inheritance are homologous with ML II in humans. Feline ML II is currently the only animal model in which to study the pathogenesis of and therapeutic interventions for this unique storage diseas

Distinct Chemotaxis Protein Paralogs Assemble into Chemoreceptor Signaling Arrays To Coordinate Signaling Output

Most chemotactic motile bacteria possess multiple chemotaxis signaling systems, the functions of which are not well characterized. Chemotaxis signaling is initiated by chemoreceptors that assemble as large arrays, together with chemotaxis coupling proteins (CheW) and histidine kinase proteins (CheA), which form a base- plate with the cytoplasmic tips of receptors. These cell pole-localized arrays mediate sensing, signaling, and signal amplification during chemotaxis responses. Membrane- bound chemoreceptors with different cytoplasmic domain lengths segregate into distinct arrays. Here, we show that a bacterium, Azospirillum brasilense, which utilizes two chemotaxis signaling systems controlling distinct motility parameters, coordi- nates its chemotactic responses through the production of two separate membrane- bound chemoreceptor arrays by mixing paralogs within chemotaxis baseplates. The polar localization of chemoreceptors of different length classes is maintained in strains that had baseplate signaling proteins from either chemotaxis system but was lost when both systems were deleted. Chemotaxis proteins (CheA and CheW) from each of the chemotaxis signaling systems (Che1 and Che4) could physically interact with one another, and chemoreceptors from both classes present in A. brasilense could interact with Che1 and Che4 proteins. The assembly of paralogs from distinct chemotaxis pathways into baseplates provides a straightforward mechanism for co- ordinating signaling from distinct pathways, which we predict is not unique to this system given the propensity of chemotaxis systems for horizontal gene transfer

An Index of Biotic Integrity for Macroinvertebrate Stream Bioassessment Conducted by Community Scientists

Community science bioassessment has great potential to inform comprehensive stream management plans, but regional analytical tools are needed to evaluate macroinvertebrate data collected through community science programs. To this end, we modified a pre-existing professional index of biotic integrity (IBI) to create a community science IBI (CS-IBI), designed for stream macroinvertebrate data collected by community scientists with minimal training. We used data collected by both professional and community scientists to develop, calibrate, and validate the CS-IBI at 76 streamsites in the Puget Lowland andWillamette Valley ecoregions of the PacificNorthwest in theUnited States. Community science data were taxonomically coarser andmore variable than data generated by professionals; however, IBI scores and assemblage data were statistically similar between community science and professional data. Stream impairment categories classified by family-level CS-IBI scores matched genus-level professional classifications 65% of the time and never diverged by \u3e1 category. CS-IBI scores were negatively related to the percentage of agriculture and land development in the watershed, although this relationship was weaker than for professional IBI scores. Despite increased variability in data generated by community scientists, our findings suggest the CS-IBI performs similarly to a professional IBI across a gradient of human influence. Although we do not advocate using the CS-IBI in regulatory settings, we believe the development of community science IBIs enhances, expands, and strengthens public partnerships, thereby supporting environmental managers’ efforts to monitor and restore degraded streams and rapidly respond to pollution events. Our hope is that the CS-IBI will improve the applicability of community science bioassessment data and serve as a model for how agencies can develop regionalized macroinvertebrate IBIs for use in comprehensive watershed management plans. Key words: citizen science, community science, stream macroinvertebrates, stream bioassessment, index of biotic integrity, watershed stressor