4,216 research outputs found

    Transport of anchovy and sardine eggs and larvae from The western Agulhas bank to the west coast during the 1993/94 and 1994/95 spawning seasons

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    The transport of eggs and larvae of anchovy Engraulus capensis and sardine Sardinops sagax from the western Agulhas Bank to the nursery grounds on the Cape west coast was investigated. Samples were takenmonthly between August 1993 and March 1994 and September 1994 and March 1995. A comparison of eggs and larval distributions with current features from selected months supports previous studies, indicating thatthe frontal jet plays an important role in the transport of the early life history stages of anchovy and sardine, but that the position of such transport can vary between the 200 and 500-m isobaths. During October 1994, November 1994 and February 1995, the greatest concentrations of eggs corresponded with areas of strong north-north-westerly flow just beyond the 200 m isobath off the Cape Peninsula, whereas in November 1993 and January 1994 eggs were concentrated farther offshore, increasing the vulnerability of developing larvae to further dispersion offshore. Offshore concentrations, intensified by strong south-easterly winds, occurred during January 1994. Areas of probable egg loss include the western Agulhas Bank, where currents flowing south-south-west can remove eggs before they are transported to the West Coast. Offshore currents also can develop west of the Cape Peninsula, but onshore currents are able to return eggs to the region of the jet, from where they are transported northwards. Other losses may result from offshore transport in the outer branch of the frontal jet off Cape Columbine. Variations in the ability of the jet current flowing north-north-west to transport eggs and larvae to areas favourable for growth and survival may influence recruitment success

    Fiber Acoustic Waveguide : A Sensor Candidate

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    Sensor development plays a key role in the field of nondestructive evaluation and process control. The annual fiber optic sensor market alone is a multimillion dollar business (1). Acoustic waves are about five orders of magnitude slower than optical waves and can also be guided in cladded glass fibers, similar to optical fibers, with low loss and low dispersion (2–7). Fiber acoustic waveguides are believed to be a very attractive and basic component for further sensor development (8). In this paper a brief theoretical description of a weakly guiding acoustic fiber (7) is given. The material selection criteria for the core and the cladding of the fiber guide, the properties of single-mode operation, and some sensing mechanisms for temperature and pressure variations are discussed. The acoustic waveguide with a liquid core is also considered

    Human-chimpanzee differences in a FZD8 enhancer alter cell-cycle dynamics in the developing neocortex.

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    The human neocortex differs from that of other great apes in several notable regards, including altered cell cycle, prolonged corticogenesis, and increased size [1-5]. Although these evolutionary changes most likely contributed to the origin of distinctively human cognitive faculties, their genetic basis remains almost entirely unknown. Highly conserved non-coding regions showing rapid sequence changes along the human lineage are candidate loci for the development and evolution of uniquely human traits. Several studies have identified human-accelerated enhancers [6-14], but none have linked an expression difference to a specific organismal trait. Here we report the discovery of a human-accelerated regulatory enhancer (HARE5) of FZD8, a receptor of the Wnt pathway implicated in brain development and size [15, 16]. Using transgenic mice, we demonstrate dramatic differences in human and chimpanzee HARE5 activity, with human HARE5 driving early and robust expression at the onset of corticogenesis. Similar to HARE5 activity, FZD8 is expressed in neural progenitors of the developing neocortex [17-19]. Chromosome conformation capture assays reveal that HARE5 physically and specifically contacts the core Fzd8 promoter in the mouse embryonic neocortex. To assess the phenotypic consequences of HARE5 activity, we generated transgenic mice in which Fzd8 expression is under control of orthologous enhancers (Pt-HARE5::Fzd8 and Hs-HARE5::Fzd8). In comparison to Pt-HARE5::Fzd8, Hs-HARE5::Fzd8 mice showed marked acceleration of neural progenitor cell cycle and increased brain size. Changes in HARE5 function unique to humans thus alter the cell-cycle dynamics of a critical population of stem cells during corticogenesis and may underlie some distinctive anatomical features of the human brain

    Principal Component Analysis Using Structural Similarity Index for Images

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    Despite the advances of deep learning in specific tasks using images, the principled assessment of image fidelity and similarity is still a critical ability to develop. As it has been shown that Mean Squared Error (MSE) is insufficient for this task, other measures have been developed with one of the most effective being Structural Similarity Index (SSIM). Such measures can be used for subspace learning but existing methods in machine learning, such as Principal Component Analysis (PCA), are based on Euclidean distance or MSE and thus cannot properly capture the structural features of images. In this paper, we define an image structure subspace which discriminates different types of image distortions. We propose Image Structural Component Analysis (ISCA) and also kernel ISCA by using SSIM, rather than Euclidean distance, in the formulation of PCA. This paper provides a bridge between image quality assessment and manifold learning opening a broad new area for future research.Comment: Paper for the methods named "Image Structural Component Analysis (ISCA)" and "Kernel Image Structural Component Analysis (Kernel ISCA)

    TEM analysis of apatite surface layers observed on zinc based glass polyalkenoate cements

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    peer-reviewedGlass polyalkenoate cements (GPCs) are acid base cements formed by the reaction of an aqueous solution of polyalkenoic acid, usually polyacrylic acid (PAA) with an acid degradable aluminosilicate glass. The result of the reaction is cement consisting of reacted and unreacted glass particles embedded in a polysalt matrix. In addition to these conventional GPCs, aluminium free glass polyalkenoate cements based on zinc silicate glasses (Zn-GPCs) exhibit significant potential as bone cements for several reasons. Primarily, they are formulated without the inclusion of aluminium (Al) [1] in the glass phase and thus eliminate clinical complications arising from the release of the Al3+ ion from the cement in vivo. Such complications have, in the past, included aluminium induced encephalopathy [2-5] and defective mineralisation of cancellous bone [6]. Secondly, Zn-GPCs set without a significant evolution of heat, when compared with commercial bone cements such as Spineplex ® (Stryker, Limerick, Ireland). Finally, these materials can be tailored to release clinically beneficial ions into surrounding tissues [7]. In addition to Zn, these cements have been synthesized to contain strontium (Sr) [8, 9]. Both Sr and Zn inhibit osteoclastic turnover and promote osteoblastic turnover, resulting in increased bone strength and decreased fracture risk [10-14].Acceptedpeer-reviewe

    Oceanography : plankton in a warmer world

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    Author Posting. © Nature Publishing Group, 2006. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 444 (2006): 695-696, doi:10.1038/444695a.Satellite data show that phytoplankton biomass and growth generally decline as the oceans’ surface waters warm up. Is this trend, seen over the past decade, a harbinger of the future for marine ecosystems

    Preferences and skills of Indian public sector teachers

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    With a sample of 700 future public sector primary teachers in India, a Discrete Choice Experiment is used to measure job preferences, particularly regarding location. General skills are also tested. Urban origin teachers and women are more averse to remote locations than rural origin teachers and men respectively. Women would require a 26-73 percent increase in salary for moving to a remote location. The results suggest that existing caste and gender quotas can be detrimental for hiring skilled teachers willing to work in remote locations. The most preferred location is home, which supports decentralised hiring, although this could compromise skills

    Effectiveness of interventions to promote healthy diet in primary care: systematic review and meta-analysis of randomised controlled trials

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    Background A diet rich in fruit, vegetables and dietary fibre and low in fat is associated with reduced risk of chronic disease. This review aimed to estimate the effectiveness of interventions to promote healthy diet for primary prevention among participants attending primary care.<p></p> Methods A systematic review of trials using individual or cluster randomisation of interventions delivered in primary care to promote dietary change over 12 months in healthy participants free from chronic disease or defined high risk states. Outcomes were change in fruit and vegetable intake, consumption of total fat and fibre and changes in serum cholesterol concentration.<p></p> Results Ten studies were included with 12,414 participants. The design and delivery of interventions were diverse with respect to grounding in behavioural theory and intervention intensity. A meta-analysis of three studies showed an increase in fruit consumption of 0.25 (0.01 to 0.49) servings per day, with an increase in vegetable consumption of 0.25 (0.06 to 0.44) serving per day. A further three studies that reported on fruit and vegetable consumption together showed a pooled increment of 0.50 (0.13 to 0.87) servings per day. The pooled effect on consumption of dietary fibre, from four studies, was estimated to be 1.97 (0.43 to 3.52) gm fibre per day. Data from five studies showed a mean decrease in total fat intake of 5.2% of total energy (1.5 to 8.8%). Data from three studies showed a mean decrease in serum cholesterol of 0.10 (-0.19 to 0.00) mmol/L.<p></p> Conclusion Presently-reported interventions to promote healthy diet for primary prevention in primary care, which illustrate a diverse range of intervention methods, may yield small beneficial changes in consumption of fruit, vegetables, fibre and fat over 12 months. The present results do not exclude the possibility that more effective intervention strategies might be developed.<p></p&gt

    All Optical Implementation of Multi-Spin Entanglement in a Semiconductor Quantum Well

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    We use ultrafast optical pulses and coherent techniques to create spin entangled states of non-interacting electrons bound to donors (at least three) and at least two Mn2+ ions in a CdTe quantum well. Our method, relying on the exchange interaction between localized excitons and paramagnetic impurities, can in principle be applied to entangle a large number of spins.Comment: 17 pages, 3 figure

    Background risk of breast cancer and the association between physical activity and mammographic density

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    This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/ by/4.0
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