4,579 research outputs found
The Marmara Sea Gateway since ~16 ky BP: non-catastrophic causes of paleoceanographic events in the Black Sea at 8.4 and 7.15 ky BP
No full textThe Late Quaternary history of connection of the Black Sea to the Eastern
Mediterranean has been intensely debated. Ryan, Pitman and coworkers
advocate two pulses of outflow from the Black Sea to the world ocean at
~16–14.7 ky BP and ~11–10 ky BP. From ~14.7–11 ky BP and from ~10–8.4
ky BP, they suggest that the level of the Black Sea fell to ~ -100 m. At 8.4 ky
BP, they further claim that a catastrophic flood occurred in a geological
instant, refilling the Black Sea with saline waters from the Mediterranean. In
contrast, we continue to gather evidence from seismic profiles and dated cores
in the Marmara Sea which demonstrate conclusively that the proposed flood
did not occur. Instead, the Black Sea has been at or above the Bosphorus sill
depth and flowing into the world ocean unabated since ~10.5 ky BP. This
conclusion is based on continuous Holocene water-column stratification
(leading to sapropel deposition in the Marmara Sea and the Aegean Sea),
proxy indicators of sea-surface salinity, and migration of endemic species
across the Bosphorus in both directions whenever appropriate hydrographic
conditions existed in the strait. The two pulses of outflow documented by
Ryan, Pitman and coworkers find support in our data, and we have modified our earlier interpretations so that these pulses now coincide with the
development of mid-shelf deltas: \Delta 2 (16–14.7 ky BP) and \Delta 1 (10.5–9 ky BP)
at the southern end of the Bosphorus Strait. However, continued Black Sea
outflow after 9 ky BP prevented the northward advection of Mediterranean
water and the entry of open-marine species into the Black Sea for more than
1000 years. Sufficient Mediterranean water to change the Sr-isotopic
composition of slope and shelf water masses was not available until ~8.4 ky
BP (along with the first arrival of many varieties of marine fauna and flora),
whereas euryhaline molluscs did not successfully populate the Black Sea
shelves until ~7.15 ky BP. Instead of relying on catastrophic events, we
recognize a slow, progressive reconnection of the Black Sea to the world
ocean, accompanied by significant time lags
Autoantibody profile differentiates BP phenotypes
No full textBullous pemphigoid (BP) is a major autoimmune blistering skin disorder, in which a majority of the autoantibodies (autoAbs) target the juxtamembranous extracellular noncollagenous 16A domain (NC16A) domain of hemidesmosomal collagen XVII. BP-autoAbs may target regions of collagen XVII other than the NC16A domain; however, correlations between epitopes of BP-autoAbs and clinical features have not been fully elucidated. To address correlations between the clinical features and specific epitopes of BP-autoAbs, we evaluated the epitope profiles of BP-autoAbs in 121 patients. A total of 87 patients showed a typical inflammatory phenotype with erythema and autoAbs targeting the anti-NC16A domain, whereas 14 patients showed a distinct noninflammatory phenotype, in which autoAbs specifically targeted the midportion of collagen XVII, but not NC16A. Interestingly, this group clinically showed significantly reduced erythema associated with scant lesional infiltration of eosinophils. Surprisingly, 7 of the 14 cases (50.0%) received dipeptidyl peptidase-IV inhibitors for the treatment of diabetes. Dipeptidyl peptidase-IV inhibitors were used in 3 of 76 (3.9%) typical cases of BP with autoAbs targeting NC16A; thus, dipeptidyl peptidase-IV inhibitors are thought to be involved in the development of atypical noninflammatory BP. This study shows that the autoAb profile differentiates between inflammatory and noninflammatory BP, and that noninflammatory BP may be associated with dipeptidyl peptidase-IV inhibitors
Bearing behaviour of aluminium sub-heads with removable beads in façade systems
No full textOccupying a substantial proportion of the overall building expense, building envelopes are the subject of ongoing research and improvement in both aesthetic and structural aspects. The aluminium window wall frame, consisting of vertical members (mullions) and horizontal members (head and sill transoms), is placed between sub-heads at the top and sub-sills at the bottom of the wall. These window walls are designed to carry lateral wind loads. Of particular importance to design stability is the bearing behaviour of aluminium sub-heads. The bearing behaviour and capacities of C-shaped sub-heads were recently investigated through a detailed experimental study at Griffith University for the development of strength prediction equations. To allow for easier assembly of façade panels, a kind of sub-head section known as sub-head with removable bead is used in aluminium window wall system. Two parts of this sub-head are connected together without any external mechanisms. The present research places emphasis on assessing the bearing behaviour of aluminium sub-heads with removable beads through comprehensive experimental testing. A total of 36 tests were conducted using six section geometries, two engagement lengths, and three bearing widths. The bearing strengths obtained from tests of aluminium sub-heads with removable beads were compared with the bearing capacities predicted using the design rules developed by the authors for conventional C-shaped aluminium sub-heads and available cold-formed steel design provisions (AISI S240 2015, TI 809-07, and SSMA 2000 specifications). As a result of the investigation, the current design equations were found to be unreliable for estimating the bearing capacity of aluminium sub-head sections with removable beads. Hence, new design expressions have been developed which accurately predict the strengths of aluminium sub-heads with removable beads under out-of-plane loads. Furthermore, the influence of the removable beads on the bearing behaviour and capacity is discussed in detail.No Full Tex
Load bearing sandwich timber walls with plywood faces and bamboo core
No full textNovel light timber sandwich panels (referred to as BCS panels herein) are manufactured by gluing plywood faces to bamboo core rings. The panels are tested in compression and in bonding shear (between bamboo and plywood). A finite element model is developed and validated against the experimental results, and is used to capture the responses of the BCS panels under axial and combined axial and bending actions. A lognormal distribution is used to represent the mechanical properties of plywood in the finite element analyses (FEA). Moreover, effect of different core configurations, face thickness, core layers and initial imperfection shapes on the axial compressive capacity of the panels are investigated. Where possible, results are compared against theoretical predictions. Current test results show that under axial compressive action, the ultimate capacity to weight ratio of the BCS panels are up to 27.3% higher than a conventional CLT panel of the same dimension. At large slenderness ratios, the proposed BCS panels have ultimate axial capacities close to the conventional CLT panels. Under combined axial and bending loading, the BCS panels outperform a CLT panel of similar size.Full Tex
Link prediction in author collaboration network based on BP neural network
No full textRecently, more and more authors have been encouraged for collaboration because it often produces good results. However, the author collaboration network contains experts in various research directions within various fields, and it is difficult for individual authors to decide which authors are best suited to their expertise. This paper uses the relationships among authors to predict new relationships that may arise, recommending each author with the collaborators they may be interested in. The data source comes from 4-year data in DBLP from 2001 to 2004. After data cleaning, the training set and test set are constructed and then used BP neural network to build model. At the same time, this article compares the performance with Logistic Regression, SVM and Random Forest. The experiment shows that the BP neural network can get better result, and it is feasible to predict links in the author collaboration network
Link prediction in author collaboration network based on BP neural network
No full textRecently, more and more authors have been encouraged for collaboration because it often produces good results. However, the author collaboration network contains experts in various research directions within various fields, and it is difficult for individual authors to decide which authors are best suited to their expertise. This paper uses the relationships among authors to predict new relationships that may arise, recommending each author with the collaborators they may be interested in. The data source comes from 4-year data in DBLP from 2001 to 2004. After data cleaning, the training set and test set are constructed and then used BP neural network to build model. At the same time, this article compares the performance with Logistic Regression, SVM and Random Forest. The experiment shows that the BP neural network can get better result, and it is feasible to predict links in the author collaboration network
Experimental study on the behaviour of hybrid fibre reinforced polymer–timber thin-walled Cee section columns
No full textHybrid fibre-reinforced polymer (FRP)-timber (HFT) think-walled structural members are a novel structural concept developed as a sustainable alternative to the steel and aluminium thin-walled structural members. HFT structures are made by combining thin-timber veneers with fibre reinforced polymer composites. Preliminary studies on HFT structures have shown promising results. However, studies into HFT structural members are still at a very early stage. This study aims to investigate the effects of fibre type, manufacturing pressure, and specimen length on the behaviour of HFT Cee section columns. Three different fibre types, namely glass FRP, natural FRP and natural FRP mat were used in the investigation, while two different manufacturing pressures, 0.1 MPa and 1 MPa were also considered. Two different specimen lengths, 280 mm and 1000 mm were considered in the investigation. In total thirty-three specimens were manufactured and tested under axial compression. In addition, material coupon tests were also carried out to determine the tensile and flexural properties of the laminates. Both membrane and flexural elastic modulus was found to increase with the manufacturing pressure. All the Cee section columns tested failed due to local buckling. Addition of FRP was found to significantly increase the load carrying capacity of the pure timber Cee section columns. HFT Cee section columns made using natural FRP mat were found to provide the highest load carrying capacity. HFT Cee section columns manufactured under 1 MPa pressure were found to perform better than the similar columns manufactured under 0.1 MPa pressure. HFT sections were also found to have a higher weight specific load capacity than similar ultra-thin-walled steel Cee section columns.No Full Tex
Shape optimisation of singly-symmetric cold-formed steel purlins
No full textThis paper presents the results of a study aiming at shape optimising singly-symmetric cold-formed steel purlins. The “self-shape” optimisation algorithm previously developed, proven to be robust and to converge to known solutions is used for this purpose. Eight optimisation cases are considered, consisting of 1.5 mm and 1.9 mm thick purlins, spanning either 3000 mm or 8000 mm and drawn with either 4, 6 or 8 elements per half cross-section. The aim of the algorithm is to minimise the cross-sectional area subjected to the following constraints: (i) the sections must at least match the second moment of area, and the inward and outward bending capacities of commercial purlins used as reference profiles, (ii) be readily manufacturable using existing roll-forming process, (iii) can be connected similarly to existing purlins by offering vertical and horizontal flat elements long enough and strategically positioned to bolt the purlins to gusset plates and screw the roof to them, respectively, and (iv) have an opening wide enough to run services. The restraints provided by the roof sheeting is considered in the algorithm when calculating the bending capacities. Results show that the algorithm converges to consistent solutions and satisfactory satisfies all constraints, resulting in manufacturable and useable purlins. When compared to the reference purlins, the optimised solutions result in saving up to 6.6% of steel. This cost saving in material is quite significant for a mass-produced product such as purlins. The efficiency of the optimised purlins relative to the reference sections were further validated with FE analysis. The FE analyses confirm that the optimised 1.5 mm thick purlins are superior to the reference section. The optimised purlins may therefore benefit the cold-formed steel industry as they represent more economical solutions without compromising on the usability and performance of the products. However, the FE model shows that the 1.9 mm thick purlins may not have the expected performance and experimental testing is fully validate the optimised sections
Uniqueness of BP⟨n⟩
No full textFix a prime number p and an integer n≥ 0. We prove that if a p-complete spectrum X satisfying a mild finiteness condition has the same mod p cohomology as BP⟨ n⟩ as a module over the Steenrod algebra, then X is weak homotopy equivalent to the p-completion of BP⟨ n⟩.The first author was supported by an ARC Discovery grant. The
second author was partially supported by the DFG through SFB-1085, and thanks the Australian National
University for hosting him while this research was conducted
IntCal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP
No full textAuthor Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2009. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 51 (2009): 1111-1150.The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is
here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets
that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in
both the 14C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves
were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04
and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available
in the Supplemental Material at www.radiocarbon.org.We would like to acknowledge support for this project from the UK Natural Environment Research
Council NE/E018807/1 and IGBP PAGES (Past Global Changes)
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