4 research outputs found

    Time-of-Flight Ranging for WSN Locationing (Project Information Sheet)

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    To develop a narrow-band RF-based Time-of-Flight (ToF) ranging method with sub-meter ranging resolution which can be adopted in wireless sensor networks (WSNs) for the purpose of localising sensor nodes. The use of RF will enable point-to-point ranging over larger distance (>50m) than current Ultra-wideband (UWB) based TOF systems with significantly less use of channel bandwidth

    Novel serum and bile protein markers predict primary sclerosing cholangitis disease severity and prognosis

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    Background & Aims: Prognostic biomarkers are lacking in primary sclerosing cholangitis, hampering patient care and the development of therapy. We aimed to identify novel protein biomarkers of disease severity and prognosis in primary sclerosing cholangitis (PSC). Methods: Using a bead-based array targeting 63 proteins, we profiled a derivation panel of Norwegian endoscopic retrograde cholangiography bile samples (55 PSC, 20 disease controls) and a Finnish validation panel (34 PSC, 10 disease controls). Selected identified proteins were measured in serum from two Norwegian PSC cohorts (n = 167 [1992-2006] and n = 138 [2008-2012]), inflammatory bowel disease (n = 96) and healthy controls (n = 100). Results: In the bile derivation panel, the levels of 14 proteins were different between PSC patients and controls (p <0.05); all were confirmed in the validation panel. Twenty-four proteins in the bile derivation panel were significantly (p <0.05) different between PSC patients with mild compared to severe cholangiographic changes (modified Amsterdam criteria); this was replicated for 18 proteins in the validation panel. Interleukin (IL)-8, matrix metallopeptidase (MMP)9/lipocalin (LCN)2-complex, S100A8/9, S100A12 and tryptophan hydroxylase (TPH)2 in the bile were associated with both a PSC diagnosis and grade of cholangiographic changes. Stratifying PSC patients according to tertiles of serum IL-8, but not MMP9/LCN2 and S100A12, provided excellent discrimination for transplant-free survival both in the serum derivation and validation cohort. Furthermore, IL-8 was associated with transplant-free survival in multivariable analyses in both serum panels independently of age and disease duration, indicating an independent influence on PSC progression. However, the Enhanced Liver Fibrosis (ELF (R)) test and Mayo risk score proved to be stronger predictors of transplant-free survival. Conclusions: Based on assaying of biliary proteins, we have identified novel biliary and serum biomarkers as indicators of severity and prognosis in PSC. Lay summary: Prognostic biomarkers are lacking in primary sclerosing cholangitis, hampering patient care and the development of therapy. We have identified inflammatory proteins including calprotectin and IL-8 as important indicators of disease severity and prognosis in bile and serum from patients with primary sclerosing cholangitis. (C) 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.Peer reviewe

    RF Time-of-Flight Locating System for WSNs (Project Information Sheet)

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    Position information of sensor nodes within wireless sensor networks (WSNs) is important in order to make use of the data recorded by the sensors themselves. We prototype an RF TOF locating system using off-the-shelf wireless sensor nodes to evaluate position estimation performance. Operation of this system requires no synchronisation or wired infrastructure between referencing architecture by using our previously developed RF TOF ranging algorithm. Our aim is to meet a position estimation accuracy of +/-0.5m under line-of-sight conditions with low latency (&lt; 2 sec)

    Radio Frequency (RF) Time-of-Flight Ranging for Wireless Sensor Networks

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    Position information of nodes within Wireless Sensor Networks (WSNs) is often a requirement in order to make use of the data recorded by the sensors themselves. On deployment the nodes normally have no prior knowledge of their position and thus a locationing mechanism is required to determine their positions. In this paper, we describe a method to determine the point-to-point range between sensor nodes as part of the locationing process. A two-way Time-of-Flight (TOF) ranging scheme is presented using narrow-band RF. The frequency difference between the transceivers involved with the point-to-point measurement is used to obtain a sub-clock TOF phase offset measurement in order to achieve high resolution TOF measurements. The ranging algorithm has been developed and prototyped on a TI CC2430 development kit with no additional hardware being required. Performance results have been obtained for the line-of-sight (LOS), non-line-of-sight (NLOS) and indoor condition. Accuracy is typically better than 7.0m RMS for the LOS condition over 250.0m and 15.8m RMS for the NLOS condition over 120.0m using a one-hundred sample average. Indoor accuracy is measured to 1.7m RMS using a 1000 sample average over 8.0m. Ranging error is linear and does not increase with increased transmitter-receiver distance. Our TOA ranging scheme demonstrates a novel system where resolution and accuracy are time dependent in comparison to alternative frequency dependent methods using narrowband RF