629 research outputs found

    Damage and repair classification in reinforced concrete beams using frequency domain data

    Get PDF
    This research aims at developing a new vibration-based damage classification technique that can efficiently be applied to a real-time large data. Statistical pattern recognition paradigm is relevant to perform a reliable site-location damage diagnosis system. By adopting such paradigm, the finite element and other inverse models with their intensive computations, corrections and inherent inaccuracies can be avoided. In this research, a two-stage combination between principal component analysis and Karhunen-Loéve transformation (also known as canonical correlation analysis) was proposed as a statistical-based damage classification technique. Vibration measurements from frequency domain were tested as possible damage-sensitive features. The performance of the proposed system was tested and verified on real vibration measurements collected from five laboratory-scale reinforced concrete beams modelled with various ranges of defects. The results of the system helped in distinguishing between normal and damaged patterns in structural vibration data. Most importantly, the system further dissected reasonably each main damage group into subgroups according to their severity of damage. Its efficiency was conclusively proved on data from both frequency response functions and response-only functions. The outcomes of this two-stage system showed a realistic detection and classification and outperform results from the principal component analysis-only. The success of this classification model is substantially tenable because the observed clusters come from well-controlled and known state conditions

    Stylobates birtlesi sp. n., a new species of carcinoecium-forming sea anemone (Cnidaria, Actiniaria, Actiniidae) from eastern Australia

    Get PDF
    This is the publisher's version, also available electronically from http://www.pensoft.net.We describe a new species of carcinoecium-forming sea anemone, Stylobates birtlesi sp. n., from sites 680-960 m deep in the Coral Sea, off the coast of Queensland, Australia. An anemone of this genus settles on a gastropod shell inhabited by a hermit crab, then covers and extends the shell to produce a chitinous structure termed a carcinoecium. Stylobates birtlesi sp. n. is symbiotic with the hermit crab Sympagurus trispinosus (Balss, 1911). The nature of marginal sphincter muscle and nematocyst size and distribution distinguish Stylobates birtlesi sp. n. from other species in the genus. The four known species are allopatric, each inhabiting a separate ocean basin of the Indo-west Pacific. We also extend the known range of Stylobates loisetteae in the Indian Ocean off the coast of Western Australia

    Synthesis and reactivity of fluorinated triaryl aluminum complexes

    Get PDF
    The addition of the Grignard 3,4,5-ArFMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-ArF)3·OEt2. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al(2,3,4-ArF)3 was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-ArF)3 shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-ArF)3·OEt2 was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane

    A systematic review of the discriminating biomechanical parameters during the single leg squat

    Get PDF
    Objective: To determine whether there are common biomechanical parameters when analysing the single leg squat movement to compare pathological and non-pathological groups and whether these parameters are able to effectively distinguish between groups. Methods: Five electronic databases were searched using MESH terms, keywords and phrases across four constructs: squat, biomechanical measures, region of interest, study design. Studies were selected based on inclusion of a quantitative biomechanical measure, compared between a pathological and a non-pathological group, and participants performed a single leg squat movement. Results: Fifteen studies were included and reviewed, where the majority of studies investigated patellofemoral pain. There was considerable variation in the biomechanical outcome measure used to compare between groups. The frontal plane projection angle was the most commonly reported measure. There was considerable variation in the manner in which the single leg squat was performed. Conclusion: Due to variation in how the single leg squat was performed, it was not possible to determine specific biomechanical parameters that distinguish between pathological and non-pathological groups. Frontal plane projection angle appeared to be a parameter that could be effectively utilised. Standardisation of the single leg squat movement is needed to allow comparison between studies of pathological and non-pathological groups

    Reproductive isolation among Acropora Species (Scleractinia: Acroporidae) in a marginal coral assemblage

    Get PDF
    Hybridization was proposed as being an important source of evolutionary novelty in broadcast-spawning reef-building corals. In addition, hybridization was hypothesized to be more frequent at the periphery of species' ranges and in marginal habitats. We tested the potential for hybridization in 2 ways: observations of the time of spawning and non-choice interspecific fertilization experiments of 4 sympatric Acropora species in a non-reefal coral assemblage at Chinwan Inner Bay (CIB), Penghu Is., Taiwan. We found that colonies of more than 1 species rarely released gametes at the same time, thus limiting the opportunities for cross-fertilization in the wild. On the few occasions when different species released gametes in synchrony, interspecific fertilization in experimental crosses was uniformly low (the proportion of eggs fertilized ranged 0%-4.58% with a mode of 0%), and interspecific-crossed embryos ceased development and died within 12 h after initially being fertilized. Ecological and experimental analyses indicated that reproductive isolation exists in these 4 Acropora species even though they have the opportunities to spawn synchronously, suggesting that hybridization is not very frequent in this marginal coral habitat at CIB

    Evaluation of molecular makers for species phylogeny of genus Acropora (Cnidaria; Scleractinia; Acroporidae)

    Get PDF
    Acropora is the most speciose genus in coral reef with 113 species currently described. Diversified morphology and potential of cross-species hybridization have drawn our attention in defining the species boundary, constructing species-level phylogeny, and inferring mechanism of speciation for this genus. Although endeavours have been taking in developing molecular markers in the last decade, several unique features such as slow evolution of mitochondrial genome and abundant ribosomal pseudogenes of Acropora neither provide little resolution for phylogenetic inference, nor equivocal conclusions in contrast to phylogenies based on fossil records and morphological characters. In this study, we evaluated 4 molecular markers, including mitochondrial cytochrome b gene (Cytb), mitochondrial intergenic spacer spanning between Cytb and ND gene (mtigs), mini-collagen intron 2 (mci2), and nuclear histone 2a and 2b gene (H2ab), for constructing species phylogeny of genus Acropora. All the 4 loci supported the two subgenera, lsopora and Acropora, as two distinct evolutionary lineages, and relocated Acropora togianensis as the fifth species in the• subgenus lsopora. However, Cytb, mtigs, and mci2 suffering from either low variability or sharing unsorted polymorphisms between the Caribbean and Indo-Pacific species provided no further resolution in resolving phylogeny in subgenus Acropora. In contrast, phylogeny constructed based on h2ab gene using Bayesian approach supported, in part, to Wallace (1999), that A. humilis group and A. austera form the basal clades of morphological phylogeny. The utility of nuclear coding genes in. resolving. species phylogeny of Acropora is highlighted

    Mineral maturity and crystallinity index are distinct characteristics of bone mineral

    Get PDF
    The purpose of this study was to test the hypothesis that mineral maturity and crystallinity index are two different characteristics of bone mineral. To this end, Fourier transform infrared microspectroscopy (FTIRM) was used. To test our hypothesis, synthetic apatites and human bone samples were used for the validation of the two parameters using FTIRM. Iliac crest samples from seven human controls and two with skeletal fluorosis were analyzed at the bone structural unit (BSU) level by FTIRM on sections 2–4 lm thick. Mineral maturity and crystallinity index were highly correlated in synthetic apatites but poorly correlated in normal human bone. In skeletal fluorosis, crystallinity index was increased and maturity decreased, supporting the fact of separate measurement of these two parameters. Moreover, results obtained in fluorosis suggested that mineral characteristics can be modified independently of bone remodeling. In conclusion, mineral maturity and crystallinity index are two different parameters measured separately by FTIRM and offering new perspectives to assess bone mineral traits in osteoporosis

    Diarrhoea among children aged under five years and risk factors in informal settlements: a cross-sectional study in Cape Town, South Africa

    Get PDF
    Background: There is limited data on the association between diarrhoea among children aged under five years (U5D) and water use, sanitation, hygiene, and socio-economics factors in low-income communities. The study investigated U5D and the associated risk factors in the Zeekoe catchment in Cape Town, South Africa. Methods: A cross-sectional study was conducted in 707 households in six informal settlements (IS) two formal settlements (FS) (March-June 2017). Results: Most IS households used public taps (74.4%) and shared toilets (93.0%), while FS households used piped water on premises (89.6%) and private toilets (98.3%). IS respondents had higher average hand-washing scores than those of FS (0.04 vs
    corecore