178 research outputs found

    Effectiveness of distributed temperature measurements for early detection of piping in river embankments

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    Abstract. Internal erosion is the cause of a significant percentage of failure and incidents involving both dams and river embankments in many countries. In the past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in dams has proved to be an effective tool for the detection of leakages and internal erosion. This work investigates the effectiveness of DTS for dike monitoring, focusing on the early detection of backward erosion piping, a mechanism that affects the foundation layer of structures resting on permeable, sandy soils. The paper presents data from a piping test performed on a large-scale experimental dike equipped with a DTS system together with a large number of accompanying sensors. The effect of seepage and piping on the temperature field is analysed, eventually identifying the processes that cause the onset of thermal anomalies around piping channels and thus enable their early detection. Making use of dimensional analysis, the factors that influence this thermal response of a dike foundation are identified. Finally some tools are provided that can be helpful for the design of monitoring systems and for the interpretation of temperature data

    Geobrain: Dutch Feasibility Database for Installing Sheet Pile Walls

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    In this paper it is shown how the knowledge embedded in case histories can be used to explicate some of the uncertainties contributing to the gap between theory and practice. With the help of computational intelligence techniques, collections of case histories in data-bases, as a type of collective memory of the geotechnical profession may be explored to turn this memory into collective brains in geo-technics: a GeoBrain. Regarding the scarcity of soil investigation data and the translation of the available data into a model, the ‘schematization factor’ has been introduced as a partial safety factor to account for the influence of data availability and the role of human expertise. Using a database of increasing size on the feasibility of installing sheet pile walls, the determination of optimal parameter values for prediction models is illustrated. It is shown that computational intelligence techniques like Bayesian Belief Networks and Genetic Algorithms can be very helpful to improve predictions of what is likely to happen in geotechnical practice

    Lessons Learned from a Full-Scale Dyke Failure Test

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    A full-scale failure test has been performed on an old river dyke in the Netherlands, to determine its actual strength against failure due to the uplift mechanism and to validate the Van model for the stability analysis of dykes prone to uplift induced failure. The test has been a success and clearly showed the relevance and significance of the uplift mechanism. In combination with earlier verifications, the Van model was found to be suitable, which has already lead to significant reductions on dyke reinforcement projects. The large gap between the actual strength and the calculated strength was confirmed. This gap appeared to be partly necessary because of the large variation in the results of dyke stability analyses by different geotechnical consultants. For the near future, the test may serve as an important benchmark for the development of a more rationally based safety philosophy

    Sensory testing in leprosy:Comparison of ballpoint pen and monofilaments

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    The 10 g monofilament has been replaced by the ballpoint pen in routine sensory testing of nerves in leprosy control in Ethiopia. Results of sensory testing between the ballpoint pen and different monofilaments on hands and feet were compared. Ballpoint pen underdiagnosis of loss of sensation was defined to occur when the pen was felt and the monofilament was not. Differences were evaluated both for individual test points (test point level) and for the test points of extremities collectively (extremity level). An extremity (either a hand or a foot) was defined as having sensory nerve function impairment (SNFI) if a supplying nerve had SNFI, which was the case when sensation was absent in two or more test points in the area supplied by that nerve. At test point level, the percentages with ballpoint pen underdiagnosis relative to the 2, 10, 20 and 50 g monofilaments were 40, 21, 9 and 7%, respectively, in the hands, and 47, 30, 15 and 7% in the feet. Ballpoint pen underdiagnosis percentages of SNFI at extremity level were 32, 18, 8 and 9% in the hands, and 37, 26, 14 and 6% in the feet. The risk of ballpoint pen underdiagnosis appears to be higher in extremities without visible damage. In conclusion, substantial levels of underdiagnosis of sensory loss with the ballpoint pen were observed. However, the consequences for the prognosis of treatment with corticosteroids in patients with the more subtle sensation loss noted here need to be established. Development and testing of guidelines is a prerequisite for the use of the ballpoint pen

    Sensory testing in leprosy:Comparison of ballpoint pen and monofilaments

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    The 10 g monofilament has been replaced by the ballpoint pen in routine sensory testing of nerves in leprosy control in Ethiopia. Results of sensory testing between the ballpoint pen and different monofilaments on hands and feet were compared. Ballpoint pen underdiagnosis of loss of sensation was defined to occur when the pen was felt and the monofilament was not. Differences were evaluated both for individual test points (test point level) and for the test points of extremities collectively (extremity level). An extremity (either a hand or a foot) was defined as having sensory nerve function impairment (SNFI) if a supplying nerve had SNFI, which was the case when sensation was absent in two or more test points in the area supplied by that nerve. At test point level, the percentages with ballpoint pen underdiagnosis relative to the 2, 10, 20 and 50 g monofilaments were 40, 21, 9 and 7%, respectively, in the hands, and 47, 30, 15 and 7% in the feet. Ballpoint pen underdiagnosis percentages of SNFI at extremity level were 32, 18, 8 and 9% in the hands, and 37, 26, 14 and 6% in the feet. The risk of ballpoint pen underdiagnosis appears to be higher in extremities without visible damage. In conclusion, substantial levels of underdiagnosis of sensory loss with the ballpoint pen were observed. However, the consequences for the prognosis of treatment with corticosteroids in patients with the more subtle sensation loss noted here need to be established. Development and testing of guidelines is a prerequisite for the use of the ballpoint pen

    RNA expression profiling in brains of familial hemiplegic migraine type 1 knock-in mice

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    Background Various CACNA1A missense mutations cause familial hemiplegic migraine type 1 (FHM1), a rare monogenic subtype of migraine with aura. FHM1 mutation R192Q is associated with pure hemiplegic migraine, whereas the S218L mutation causes hemiplegic migraine, cerebellar ataxia, seizures, and mild head trauma-induced brain edema. Transgenic knock-in (KI) migraine mouse models were generated that carried either the FHM1 R192Q or the S218L mutation and were shown to exhibit increased CaV2.1 channel activity. Here we investigated their cerebellar and caudal cortical transcriptome. Methods Caudal cortical and cerebellar RNA expression profiles from mutant and wild-type mice were studied using microarrays. Respective brain regions were selected based on their relevance to migraine aura and ataxia. Relevant expression changes were further investigated at RNA and protein level by quantitative polymerase chain reaction (qPCR) and/or immunohistochemistry, respectively. Results Expression differences in the cerebellum were most pronounced in S218L mice. Particularly, tyrosine hydroxylase, a marker of delayed cerebellar maturation, appeared strongly upregulated in S218L cerebella. In contrast, only minimal expression differences were observed in the caudal cortex of either mutant mice strain. Conclusion Despite pronounced consequences of migraine gene mutations at the neurobiological level, changes in cortical RNA expression in FHM1 migraine mice compared to wild-type are modest. In contrast, pronounced RNA expression changes are seen in the cerebellum of S218L mice and may explain their cerebellar ataxia phenotyp

    Combination of plasma amyloid beta(1-42/1-40) and glial fibrillary acidic protein strongly associates with cerebral amyloid pathology

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    BACKGROUND: Blood-based biomarkers for Alzheimer's disease (AD) might facilitate identification of participants for clinical trials targeting amyloid beta (Abeta) accumulation, and aid in AD diagnostics. We examined the potential of plasma markers Abeta(1-42/1-40), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) to identify cerebral amyloidosis and/or disease severity. METHODS: We included individuals with a positive (n = 176: 63 ± 7 years, 87 (49%) females) or negative (n = 76: 61 ± 9 years, 27 (36%) females) amyloid PET status, with syndrome diagnosis subjective cognitive decline (18 PET+, 25 PET-), mild cognitive impairment (26 PET+, 24 PET-), or AD-dementia (132 PET+). Plasma Abeta(1-42/1-40), GFAP, and NfL were measured by Simoa. We applied two-way ANOVA adjusted for age and sex to investigate the associations of the plasma markers with amyloid PET status and syndrome diagnosis; logistic regression analysis with Wald's backward selection to identify an optimal panel that identifies amyloid PET positivity; age, sex, and education-adjusted linear regression analysis to investigate associations between the plasma markers and neuropsychological test performance; and Spearman's correlation analysis to investigate associations between the plasma markers and medial temporal lobe atrophy (MTA). RESULTS: Abeta(1-42/1-40) and GFAP independently associated with amyloid PET status (p = 0.009 and p  0.33, p < 0.001). Abeta(1-42/1-40) showed a moderate negative correlation with MTA (Spearman's rho = - 0.24, p = 0.001). DISCUSSION AND CONCLUSIONS: Combination of plasma Abeta(1-42/1-40) and GFAP provides a valuable tool for the identification of amyloid PET status. Furthermore, plasma GFAP and NfL associate with various disease severity measures suggesting potential for disease monitoring

    Adaptation Strategies for Personalized Gait Neuroprosthetics

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    Personalization of gait neuroprosthetics is paramount to ensure their efficacy for users, who experience severe limitations in mobility without an assistive device. Our goal is to develop assistive devices that collaborate with and are tailored to their users, while allowing them to use as much of their existing capabilities as possible. Currently, personalization of devices is challenging, and technological advances are required to achieve this goal. Therefore, this paper presents an overview of challenges and research directions regarding an interface with the peripheral nervous system, an interface with the central nervous system, and the requirements of interface computing architectures. The interface should be modular and adaptable, such that it can provide assistance where it is needed. Novel data processing technology should be developed to allow for real-time processing while accounting for signal variations in the human. Personalized biomechanical models and simulation techniques should be developed to predict assisted walking motions and interactions between the user and the device. Furthermore, the advantages of interfacing with both the brain and the spinal cord or the periphery should be further explored. Technological advances of interface computing architecture should focus on learning on the chip to achieve further personalization. Furthermore, energy consumption should be low to allow for longer use of the neuroprosthesis. In-memory processing combined with resistive random access memory is a promising technology for both. This paper discusses the aforementioned aspects to highlight new directions for future research in gait neuroprosthetics.AK is funded by a faculty endowment by adidas AG. MA, SKH, NM, MN, RJQ, R-DR, RJT are supported by NSF CPS grant 1739800, VA Merit Reviews A2275-R and 3056, and the NIH (5T32EB004314-15, R01 NS040547-13). MS and AG are funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 803035). AJd-A, JMF-L, and JCM are supported by coordinated grants RTI2018-097290-B-C31/C32/C33 (TAILOR project) funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. MR is funded by the Lo3-ML project by the Federal Ministry for Education, Science and Technology (BMBF) (Funding No. 16ES1142K). AC, SS, and MV were supported by the European Research Council (ERC) under the project NGBMI (759370), the Einstein Stiftung Berlin, the ERA-NET NEURON project HYBRIDMIND (BMBF, 01GP2121A and -B) and the BMBF project NEO (13GW0483C)

    Community genetics in the time of next-generation molecular technologies

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    Understanding the interactions of co-occurring species within and across trophic levels provides key information needed for understanding the ecological and evolutionary processes that underlie biological diversity. As genetics has only recently been integrated into the study of community-level interactions, the time is right for a critical evaluation of potential new, gene-based approaches to studying communities. Next-generation molecular techniques, used in parallel with field-based observations and manipulative experiments across spatio-temporal gradients, are key to expanding our understanding of community-level processes. Here, we introduce a variety of ‘-omics’ tools, with recent studies of plant–insect herbivores and of ectomycorrhizal systems providing detailed examples of how next-generation approaches can revolutionize our understanding of interspecific interactions. We suggest ways that novel technologies may convert community genetics from a field that relies on correlative inference to one that reveals causal mechanisms of genetic co-variation and adaptations within communities

    FORUM:Remote testing for psychological and physiological acoustics

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    Acoustics research involving human participants typically takes place in specialized laboratory settings. Listening studies, for example, may present controlled sounds using calibrated transducers in sound-attenuating or anechoic chambers. In contrast, remote testing takes place outside of the laboratory in everyday settings (e.g., participants' homes). Remote testing could provide greater access to participants, larger sample sizes, and opportunities to characterize performance in typical listening environments at the cost of reduced control of environmental conditions, less precise calibration, and inconsistency in attentional state and/or response behaviors from relatively smaller sample sizes and unintuitive experimental tasks. The Acoustical Society of America Technical Committee on Psychological and Physiological Acoustics launched the Task Force on Remote Testing (https://tcppasa.org/remotetesting/) in May 2020 with goals of surveying approaches and platforms available to support remote testing and identifying challenges and considerations for prospective investigators. The results of this task force survey were made available online in the form of a set of Wiki pages and summarized in this report. This report outlines the state-of-the-art of remote testing in auditory-related research as of August 2021, which is based on the Wiki and a literature search of papers published in this area since 2020, and provides three case studies to demonstrate feasibility during practice
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