29 research outputs found

    Efficient numerical computation and experimental study of temporally long equilibrium scour development around abutment

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    YesFor the abutment bed scour to reach its equilibrium state, a long flow time is needed. Hence, the employment of usual strategy of simulating such scouring event using the 3D numerical model is very time consuming and less practical. In order to develop an applicable model to consider temporally long abutment scouring process, this study modifies the common approach of 2D shallow water equations (SWEs) model to account for the sediment transport and turbulence, and provides a realistic approach to simulate the long scouring process to reach the full scour equilibrium. Due to the high demand of the 2D SWEs numerical scheme performance to simulate the abutment bed scouring, a recently proposed surface gradient upwind method (SGUM) was also used to improve the simulation of the numerical source terms. The abutment scour experiments of this study were conducted using the facility of Hydraulics Laboratory at Nanyang Technological University, Singapore to compare with the presented 2D SGUM-SWEs model. Fifteen experiments were conducted over a total period of 3059.7 hours experimental time (over 4.2 months). The comparison shows that the 2D SGUM-SWEs model gives good representation to the experimental results with the practical advantage

    Mutations in fam20b and xylt1 Reveal That Cartilage Matrix Controls Timing of Endochondral Ossification by Inhibiting Chondrocyte Maturation

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    Differentiating cells interact with their extracellular environment over time. Chondrocytes embed themselves in a proteoglycan (PG)-rich matrix, then undergo a developmental transition, termed ā€œmaturation,ā€ when they express ihh to induce bone in the overlying tissue, the perichondrium. Here, we ask whether PGs regulate interactions between chondrocytes and perichondrium, using zebrafish mutants to reveal that cartilage PGs inhibit chondrocyte maturation, which ultimately dictates the timing of perichondral bone development. In a mutagenesis screen, we isolated a class of mutants with decreased cartilage matrix and increased perichondral bone. Positional cloning identified lesions in two genes, fam20b and xylosyltransferase1 (xylt1), both of which encode PG synthesis enzymes. Mutants failed to produce wild-type levels of chondroitin sulfate PGs, which are normally abundant in cartilage matrix, and initiated perichondral bone formation earlier than their wild-type siblings. Primary chondrocyte defects might induce the bone phenotype secondarily, because mutant chondrocytes precociously initiated maturation, showing increased and early expression of such markers as runx2b, collagen type 10a1, and ihh co-orthologs, and ihha mutation suppressed early perichondral bone in PG mutants. Ultrastructural analyses demonstrated aberrant matrix organization and also early cellular features of chondrocyte hypertrophy in mutants. Refining previous in vitro reports, which demonstrated that fam20b and xylt1 were involved in PG synthesis, our in vivo analyses reveal that these genes function in cartilage matrix production and ultimately regulate the timing of skeletal development

    Diet and food strategies in a southern al-Andalusian urban environment during Caliphal period, ecija, Sevilla

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    The Iberian medieval period is unique in European history due to the widespread socio-cultural changes that took place after the arrival of Arabs, Berbers and Islam in 711 AD. Recently, isotopic research has been insightful on dietary shifts, status, resource availability and the impact of environment. However, there is no published isotopic research exploring these factors in southern Iberian populations, and as the history of this area differs to the northern regions, this leaves a significant lacuna in our knowledge. This research fills this gap via isotopic analysis of human (n = 66) and faunal (n = 13) samples from the 9th to the 13th century Ɖcija, a town renowned for high temperatures and salinity. Stable carbon (Ī“13C) and nitrogen (Ī“15N) isotopes were assessed from rib collagen, while carbon (Ī“13C) values were derived from enamel apatite. Human diet is consistent with C3 plant consumption with a very minor contribution of C4 plants, an interesting feature considering the suitability of Ɖcija to C4 cereal production. Ī“15N values vary among adults, which may suggest variable animal protein consumption or isotopic variation within animal species due to differences in foddering. Consideration of Ī“13C collagen and apatite values together may indicate sugarcane consumption, while moderate Ī“15N values do not suggest a strong aridity or salinity effect. Comparison with other Iberian groups shows similarities relating to time and location rather than by religion, although more multi-isotopic studies combined with zooarchaeology and botany may reveal subtle differences unobservable in carbon and nitrogen collagen studies alone.OLC is funded by Plan Galego I2C mod.B (ED481D 2017/014). The research was partially funded by the projects ā€œGalician Paleodietā€ and by Consiliencia network (ED 431D2017/08) Xunta de GaliciaS

    Evidence-based Kernels: Fundamental Units of Behavioral Influence

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    This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behaviorā€“influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of its components would render it inert. Existing evidence shows that a variety of kernels can influence behavior in context, and some evidence suggests that frequent use or sufficient use of some kernels may produce longer lasting behavioral shifts. The analysis of kernels could contribute to an empirically based theory of behavioral influence, augment existing prevention or treatment efforts, facilitate the dissemination of effective prevention and treatment practices, clarify the active ingredients in existing interventions, and contribute to efficiently developing interventions that are more effective. Kernels involve one or more of the following mechanisms of behavior influence: reinforcement, altering antecedents, changing verbal relational responding, or changing physiological states directly. The paper describes 52 of these kernels, and details practical, theoretical, and research implications, including calling for a national database of kernels that influence human behavior

    Spatial and temporal changes in egg production in the western rock lobster (Panulirus cygnus) fishery

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    Size at maturity in the western rock lobster (Panulirus cygnus) fishery in Australia increases from north to south and female lobsters carry either one or two batches of eggs per season depending on their carapace length. There has been a steady decrease in the size at first maturity of western rock lobster over the last 30 years, and there are now significantly more small females, many below the legal minimum size, contributing to the brood stock than any time since the fishery has been researched. Biological data were used to show the current contribution to egg production in different management regions of the fishery and historical length-frequency data were used to show how egg production has changed in those regions overtime. Reasons for the change in size at maturity in this fishery are unclear, but the outcome has been that egg production is now more evenly distributed across management zones. Egg production was high at Abrolhos Islands in the 1990s owing to strong year classes of breeding animals entering the fishery over those years. In the period since 2000, egg production has fallen sharply at the islands, but has increased in the coastal population compared with the 1980s and 1990s
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