7,171 research outputs found

    The superposition of algebraic solitons for the modified Korteweg-de Vries equation

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    Influence of amendments on soil structure and soil loss under simulated rainfall Chinaā€™s loess plateau

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    Macromolecule polymers are significant types of chemical amendments because of their special structure, useful functions and low cost. Macromolecule polymers as soil amendment provide new territory for studying Chinaā€™s agricultural practices and for soil and water conservation, because polymers have the ability to improve soil structure, increase rainfall penetration and control slope runoff. Through indoor laboratory experiments and outdoor artificial rainfall simulations, this study applied different consistencies of three amendments; polypropylene acid (PPA), polythene alcoholic (PTA) and urea-formaldehyde poly-condensate (UR) to Chinaā€™s Loess and determined their effects on soil physical properties and on runoff-sediment yield. The results indicate that as a result of applying the amendments, (1) the water-stable soil aggregates content increases by 17.3%, the soil permeability increases by 41.8%, the soil density decreases by 11.2% and the soil water content increases by 28.0% compared to the control; (2) three amendment applied on sloping land can delay runoff and decrease runoff velocity; decrease erosive forces of raindrop impact and flowing water, reduce surface crusting and improve water infiltration, delay runoff engenderation and decrease runnoff velocity and soil erosion yield. Finally, this study also ascertained optimal application quantities and the most effective sort in three amendments, which PPA is most effective at lowering surface runoff, reducing soil loss and increasing soil penetration. These three amendments have broad potential for soil and water conservation; however, the duration of their effect and the optimal application quantities need to be researched further.Key words: Amendment, Runoff-Sediment Yield, Soil Physical Properties, Soil erosio

    Deep Learning using K-space Based Data Augmentation for Automated Cardiac MR Motion Artefact Detection

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    Quality assessment of medical images is essential for complete automation of image processing pipelines. For large population studies such as the UK Biobank, artefacts such as those caused by heart motion are problematic and manual identification is tedious and time-consuming. Therefore, there is an urgent need for automatic image quality assessment techniques. In this paper, we propose a method to automatically detect the presence of motion-related artefacts in cardiac magnetic resonance (CMR) images. As this is a highly imbalanced classification problem (due to the high number of good quality images compared to the low number of images with motion artefacts), we propose a novel k-space based training data augmentation approach in order to address this problem. Our method is based on 3D spatio-temporal Convolutional Neural Networks, and is able to detect 2D+time short axis images with motion artefacts in less than 1ms. We test our algorithm on a subset of the UK Biobank dataset consisting of 3465 CMR images and achieve not only high accuracy in detection of motion artefacts, but also high precision and recall. We compare our approach to a range of state-of-the-art quality assessment methods.Comment: Accepted for MICCAI2018 Conferenc

    SOCIAL NETWORK PRIVACY DISPOSITIONS: AN OBJECTIVE MEASUREMENT SCALE AND A CAUSAL MODEL

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    The Information Systems literature has substantially advanced understanding of privacy in both offline contexts and online environments. Despite the rich understanding, existing studies predominately focused on elucidating privacy issues specific to individuals. The increasingly popular usage of mobile apps with social media integration has fundamentally challenged current understanding and conceptualization of information privacy. In particular, mobile apps allow information collection beyond individualsā€™ personal scope (i.e., his/her personal information) and extend the scope of acquisition into individualsā€™ online social networks (i.e., his/her list of friends on Facebook). To fill this gap in the literature, drawing on the Communication Privacy Management Theory, this proposal focuses on three unique dimensions of social network privacy dispositions, namely permeability, ownership, and linkage. Second, we propose to operationalize these three dimensions of social network privacy dispositions using a second-order reflective construct, and we plan to develop an objective measurement scale for it. Lastly, we plan to validate the construct using a nomological network

    Fractional Anisotropy in Corpus Callosum Is Associated with Facilitation of Motor Representation during Ipsilateral Hand Movements

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    BACKGROUND: Coactivation of primary motor cortex ipsilateral to a unilateral movement (M1(ipsilateral)) has been observed, and the magnitude of activation is influenced by the contracting muscles. It has been suggested that the microstructural integrity of the callosal motor fibers (CMFs) connecting M1 regions may reflect the observed response. However, the association between the structural connectivity of CMFs and functional changes in M1(ipsilateral) remains unclear. The purpose of this study was to investigate the relationship between functional changes within M1(ipsilateral) during unilateral arm or leg movements and the microstructure of the CMFs connecting both homotopic representations (arm or leg). METHODS: Transcranial magnetic stimulation was used to assess changes in motor evoked potentials (MEP) in an arm muscle during unilateral movements compared to rest in fifteen healthy adults. Functional magnetic resonance imaging was then used to identify regions of M1 associated with either arm or leg movements. Diffusion-weighted imaging data was acquired to generate CMFs for arm and leg areas using the areas of activation from the functional imaging as seed masks. Individual values of regional fractional anisotropy (FA) of arm and leg CMFs was then calculated by examining the overlap between CMFs and a standard atlas of corpus callosum. RESULTS: The change in the MEP was significantly larger in the arm movement compared to the leg movement. Additionally, regression analysis revealed that FA in the arm CMFs was positively correlated with the change in MEP during arm movement, whereas a negative correlation was observed during the leg movement. However, there was no significant relationship between FA in the leg CMF and the change in MEP during the movements. CONCLUSIONS: These findings suggest that individual differences in interhemispheric structural connectivity may be used to explain a homologous muscle-dominant effect within M1(ipsilateral) hand representation during unilateral movement with topographical specificity

    Validity and Reliability of Curl-Up Test on Assessing the Core Endurance for Kindergarten Children in Hong Kong

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    Objective: The purpose of this study was to examine the test-retest reliability and the criterion validity of a curlup test (CUT) as a measure of core stability, core endurance and dynamic stability in kindergarten children. CUT performance was also compared to half hold lying test (HHLT) and walking time on course (WTC) among without obstacle, with low obstacle and high obstacle measures of core stability, core endurance and dynamic stability. Methods: To estimate reliability, 33 males and 27 female kindergarten children (M aged=4.5 years old) performed the CUT on 2 different days. In the validity phase of the study, scores of all participants were obtained on three field test measures of core stability, core endurance and dynamic stability (CUT, HHLT and WTC). Results: Results indicate that the MCU test has no significant correlation on intra-class test-retest reliability (R=0.13, p>0.01). The criterion validity of the CUT for kindergarten children has is comparable to that of the HHLT(r=0.98, p<0.01) and WTC without obstacle(r=0.96, p<0.01), with low obstacle (r=0.96, p<0.01) and with high obstacle (r=0.98, p<0.01). Result indicates that the CUT test cannot produces reasonably accurate and stable measures of core stability, core endurance and dynamic stability. Conclusion: These preliminary findings provide evidences into the CUT test cannot produces reasonably accurate and stable measures of core stability, core endurance and dynamic stability for kindergarten children

    Enhanced survival and regeneration of axotomized retinal ganglion cells by a mixture of herbal extracts

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    The aim of this study is to investigate the effects of Panax quinquefolius L. extract (PQE), Ginkgo biloba extract (GBE), and Hypericum perforatum extract (HPE), in combination or alone, on the survival and regeneration of axotomized retinal ganglion cells (RGCs) in an optic nerve transection model in adult hamsters. Unilateral transection of the optic nerve was performed to evaluate the effects of herbal extracts on the survival of axotomized RGCs. Effects of the herbal extracts on axonal regeneration of axotomized RGCs, on the other hand, were studied by attaching a peripheral nerve graft onto the transected ocular stump to induce regeneration. Operated animals received daily oral administration of vehicle or herbal extracts (PQE, GBE, and HPE), alone or in combination, for 7 and 21 days, respectively, in the survival and regeneration experiments. Surviving and regenerating RGCs were retrogradely labeled with Fluoro-Gold. The eyes were then enucleated and the retinas were flat-mounted for the counting of the labeled RGCs. Treatment with PQE, GBE and HPE alone failed to offer neuroprotection to injured RGCs. However, treatment with Menta-FX, a mixture of PQE, GBE, and HPE, significantly augmented RGC survival 7 days postaxotomy. Treatment with Menta-FX also induced a significant (87%) increase in the number of regenerating RGCs 21 days after optic nerve transection. This study demonstrates that herbs can act as a potential neuroprotective agent for damaged RGCs. It also suggests that the therapeutic value of herbal remedies can be maximized by the use of mixtures of appropriate herbs.published_or_final_versio

    High-temperature antiferromagnetism in molecular semiconductor thin films and nanostructures

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    The viability of dilute magnetic semiconductors in applications is linked to the strength of the magnetic couplings, and room temperature operation is still elusive in standard inorganic systems. Molecular semiconductors are emerging as an alternative due to their long spin-relaxation times and ease of processing, but, with the notable exception of vanadium-tetracyanoethylene, magnetic transition temperatures remain well below the boiling point of liquid nitrogen. Here we show that thin films and powders of the molecular semiconductor cobalt phthalocyanine exhibit strong antiferromagnetic coupling, with an exchange energy reaching 100ā€‰K. This interaction is up to two orders of magnitude larger than in related phthalocyanines and can be obtained on flexible plastic substrates, under conditions compatible with routine organic electronic device fabrication. Ab initio calculations show that coupling is achieved via superexchange between the singly occupied a(1g) ([Image: see text]) orbitals. By reaching the key milestone of magnetic coupling above 77ā€‰K, these results establish quantum spin chains as a potentially useable feature of molecular films
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