1,868 research outputs found

    A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results

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    The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for use with cohesionless soils in diaphragm wall analysis on the Personal Computer with the BMCOL7 program. An analogous W-y curve is proposed, an elastic-plastic model with line-load limits developed from classical earth-pressure theories. A new formula for predicting a horizontal walI modulus for cohesionless soiIs from the pressuremeter modulus is developed for use in predicting the displacements on the W-y curves. The resulting modulus values are shown to yield reasonable displacements values. A new procedure for modeling preloaded tie-back anchors and staged excavation for diaphragm walIs was developed, utiIizing multiple computer runs, updated the W-y curves, and superposition of deflections. These new developments were applied to a parametric study of a deflection-critical section of the new Bonnevilie Nav-Lock Buttress Diaphragm Wall, for which extensive high-quality pressuremeter test results were available. Deflection curves of the wall are presented, showing the effect of variations in anchor preload, walI cracking, anchor slip, at-rest pressure, and soiI modulus. The results indicate that preloading will reduce wall deflections by at least 4-fold, but that wall cracking can potentially double deflections. Safety factors against passive soil failure were determined to be about 5 at anchor preload, and more than 40 after fulI excavation

    Financing hospital expansion

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    Environmental tolerances and drivers of deepwater seagrass change: implications and tools for coastal development management

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    While research has focused on shallow water coastal seagrasses over the last 20 years, little is known of the ecological role, tolerances and drivers of their deepwater (>10) counterparts. Within the Great Barrier Reef World Heritage Area, deepwater seagrasses are estimated to occupy more than 35,000 km2 of the reef lagoon. These deepwater meadows are often within the footprint of port and shipping activity where dredging, associated plumes and ship movements are major threats to their long term survival. We present initial findings from an ongoing research program to determine the drivers of seasonal and inter-annual change in deepwater tropical seagrasses. Seagrass abundance, seed bank status and recruitment, productivity, irradiance and temperature along with detailed spectral profiles have been measured in three geographically distinct deepwater seagrass meadows since early 2012. Manipulative lab experiments were initiated in mid-2013 to assess the adaptive photophysiological characteristics of the plants. This research will identify key environmental cues which will be used in developing local management strategies for mitigating coastal developmental impacts along the Great Barrier Reef

    Environmental tolerances and drivers of deepwater seagrass change: implications and tools for coastal development management

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    While research has focused on shallow water coastal seagrasses over the last 20 years, little is known of the ecological role, tolerances and drivers of their deepwater (>10) counterparts. Within the Great Barrier Reef World Heritage Area, deepwater seagrasses are estimated to occupy more than 35,000 km2 of the reef lagoon. These deepwater meadows are often within the footprint of port and shipping activity where dredging, associated plumes and ship movements are major threats to their long term survival. We present initial findings from an ongoing research program to determine the drivers of seasonal and inter-annual change in deepwater tropical seagrasses. Seagrass abundance, seed bank status and recruitment, productivity, irradiance and temperature along with detailed spectral profiles have been measured in three geographically distinct deepwater seagrass meadows since early 2012. Manipulative lab experiments were initiated in mid-2013 to assess the adaptive photophysiological characteristics of the plants. This research will identify key environmental cues which will be used in developing local management strategies for mitigating coastal developmental impacts along the Great Barrier Reef

    Structural and Functional Determinants of Rodent and Human Surfactant Protein A: A Synthesis of Binding and Computational Data

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    Surfactant protein A (SP-A) provides surfactant stability, first line host defense, and lung homeostasis by binding surfactant phospholipids, pathogens, alveolar macrophages (AMs), and epithelial cells. Non-primates express one SP-A protein whereas humans express two: SP-A1 and SP-A2 with core intra- and inter-species differences in the collagen-like domain. Here, we used macrophages and solid phase binding assays to discern structural correlates of rat (r) and human (h) SP-A function. Binding assays using recombinant rSP-A expressed in insect cells showed that lack of proline hydroxylation, truncations of amino-terminal oligomerization domains, and site-directed serine (S) or alanine (A) mutagenesis of cysteine 6 (C6S), glutamate 195 (E195A), and glutamate 171 (E171A) in the carbohydrate recognition domain (CRD) all impaired SP-A binding. Replacement of arginine 197 with alanine found in hSP-A (R197A), however, restored the binding of hydroxyproline-deficient rSP-A to the SP-A receptor SP-R210 similar to native rat and human SP-A. In silico calculation of Ca++ coordination bond length and solvent accessibility surface area revealed that the “humanized” R197A substitution alters topology and solvent accessibility of the Ca++ coordination residues of the CRD domain. Binding assays in mouse AMs that were exposed to either endogenous SP-A or hSP-A1 (6A2) and hSP-A2 (1A0) isoforms in vivo revealed that mouse SP-A is a functional hybrid of hSP-A1 and hSP-A2 in regulating SP-A receptor occupancy and binding affinity. Binding assays using neonatal and adult human AMs indicates that the interaction of SP-A1 and SP-A2 with AMs is developmentally regulated. Furthermore, our data indicate that the auxiliary ion coordination loop encompassing the conserved E171 residue may comprise a conserved site of interaction with macrophages, and SP-R210 specifically, that merits further investigation to discern conserved and divergent SP-A functions between species. In summary, our findings support the notion that complex structural adaptation of SP-A regulate conserved and species specific AM functions in vertebrates

    Awareness and willingness to use HIV pre-exposure prophylaxis amongst gay and bisexual men in Scotland: implications for biomedical HIV prevention

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    Objectives:<p></p> To investigate the awareness of, and willingness to use, HIV Pre-Exposure Prophylaxis (PrEP), and willingness to take part in a PrEP study among gay and bisexual men in Scotland.<p></p> Methods:<p></p> Cross-sectional survey of 17 gay commercial venues in Glasgow and Edinburgh in May 2011 (N = 1515, 65.2% response rate); 1393 are included in the analyses.<p></p> Results:<p></p> Just under one-third of participants had heard of PrEP (n = 434; 31.2%), with awareness associated with being aged older than 35 years, talking to UAI partners about HIV, and with having had an HIV or STI test in the previous 12 months. Around half were willing to take part in a PrEP study (n = 695; 49.9%) or to take PrEP on a daily basis (n = 756; 54.3%). In multivariate analysis, willingness to take PrEP was associated with lower levels of education, regular gay scene attendance, ‘high-risk’ unprotected anal intercourse (UAI) and testing for HIV or STI in the previous 12 months. Reasons for not wanting to participate in a PrEP study or take PrEP included perceptions of low personal risk of HIV and concerns with using medication as an HIV prevention method.<p></p> Conclusions:<p></p> There is a willingness to engage in new forms of HIV prevention and research amongst a significant number of gay and bisexual men in Scotland. Future biomedical HIV interventions need to consider the links between sexual risk behaviour, testing, and potential PrEP use

    Predicting the HMA-LMA status in marine sponges by machine learning

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    The dichotomy between high microbial abundance (HMA) and low microbial abundance (LMA) sponges has been observed in sponge-microbe symbiosis, although the extent of this pattern remains poorly unknown. We characterized the differences between the microbiomes of HMA (n=19) and LMA (n=17) sponges (575 specimens) present in the Sponge Microbiome Project. HMA sponges were associated with richer and more diverse microbiomes than LMA sponges, as indicated by the comparison of alpha diversity metrics. Microbial community structures differed between HMA and LMA sponges considering Operational Taxonomic Units (OTU) abundances and across microbial taxonomic levels, from phylum to species. The largest proportion of microbiome variation was explained by the host identity. Several phyla, classes, and OTUs were found differentially abundant in either group, which were considered “HMA indicators” and “LMA indicators”. Machine learning algorithms (classifiers) were trained to predict the HMA-LMA status of sponges. Among nine different classifiers, higher performances were achieved by Random Forest trained with phylum and class abundances. Random Forest with optimized parameters predicted the HMA-LMA status of additional 135 sponge species (1,232 specimens) without a priori knowledge. These sponges were grouped in four clusters, from which the largest two were composed of species consistently predicted as HMA (n=44) and LMA (n=74). In summary, our analyses shown distinct features of the microbial communities associated with HMA and LMA sponges. The prediction of the HMA-LMA status based on the microbiome profiles of sponges demonstrates the application of machine learning to explore patterns of host-associated microbial communities

    Common variants in FOXP1 are associated with generalized vitiligo

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    In a recent genome-wide association study of generalized vitiligo, we identified ten confirmed susceptibility loci. By testing additional loci that showed suggestive association in the genome-wide study, using two replication cohorts of European descent, we observed replicated association of generalized vitiligo with variants at 3p13 encompassing FOXP1 (rs17008723, combined P = 1.04 × 10−8) and with variants at 6q27 encompassing CCR6 (rs6902119, combined P = 3.94 × 10−7)

    Variant of TYR and Autoimmunity Susceptibility Loci in Generalized Vitiligo.

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    BACKGROUND Generalized vitiligo is an autoimmune disease characterized by melanocyte loss, which results in patchy depigmentation of skin and hair, and is associated with an elevated risk of other autoimmune diseases. METHODS To identify generalized vitiligo susceptibility loci, we conducted a genomewide association study. We genotyped 579,146 single-nucleotide polymorphisms (SNPs) in 1514 patients with generalized vitiligo who were of European-derived white (CEU) ancestry and compared the genotypes with publicly available control genotypes from 2813 CEU persons. We then tested 50 SNPs in two replication sets, one comprising 677 independent CEU patients and 1106 CEU controls and the other comprising 183 CEU simplex trios with generalized vitiligo and 332 CEU multiplex families. RESULTS We detected significant associations between generalized vitiligo and SNPs at several loci previously associated with other autoimmune diseases. These included genes encoding major-histocompatibility-complex class I molecules (P=9.05×10−23) and class II molecules (P=4.50×10−34), PTPN22 (P=1.31×10−7), LPP (P=1.01×10−11), IL2RA (P=2.78×10−9), UBASH3A (P=1.26×10−9), and C1QTNF6 (P=2.21×10−16). We also detected associations between generalized vitiligo and SNPs in two additional immune-related loci, RERE (P=7.07×10−15) and GZMB (P=3.44×10−8), and in a locus containing TYR (P=1.60×10−18), encoding tyrosinase. CONCLUSIONS We observed associations between generalized vitiligo and markers implicating multiple genes, some associated with other autoimmune diseases and one (TYR) that may mediate target-cell specificity and indicate a mutually exclusive relationship between susceptibility to vitiligo and susceptibility to melanoma
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