35,281 research outputs found
Diagnostic accuracy of a non-invasive spot-check hemoglobin meter, Masimo Rad-67® Pulse CO-Oximeter®, in detection of anemia in antenatal care settings in Kenya.
No full textBackground: Point of care hemoglobin meters play key roles in increasing access to anemia screening in antenatal care especially in settings with limited access to laboratories. We aimed to determine the diagnostic accuracy of a non-invasive spot-check hemoglobin (SpHb) meter, Masimo Rad-67® Pulse CO-Oximeter®, in the diagnosis of anemia in pregnant women attending antenatal care clinics in Kilifi, Kenya. Methods: This was a diagnostic accuracy study that retrospectively evaluated SpHb against a validated reference standard of laboratory assessed hemoglobin (Lab Hb) by a SYSMEX XN-330 automated hematology analyzer. The study was nested within a prospective pregnancy cohort study that recruited unselected pregnant women from antenatal care clinics in two public hospitals in Kilifi County, coastal Kenya. Records with both SpHb and Lab Hb were selected from pregnancy visits between May 2021 and December 2022. Linear regression and Bland-Altman analysis were performed to compare the two tests and diagnostic accuracy parameters obtained for the diagnosis of anemia. Results: A total of 2,975 records (from 2,203 unique participants), with paired SpHb and Lab Hb were analyzed. Linear regression showed a significant but weak positive correlation, a proportional bias of 0.44 (95% CI 0.41–0.47) and a constant of 7.59 (95% CI 7.30–7.87, p < 0.001). The median bias was 1.70 g/dl, with limits of agreement of −0.80 to 4.20. SpHb tended to be higher than Lab Hb on the low hemoglobin range but lower than Lab Hb on the high hemoglobin range. The sensitivity of SpHb in detecting anemia was 18.66%. Prevalence, specificity, positive predictive value, and negative predictive values were 46.37%, 96.77%, 83.33%, and 57.92% respectively. Conclusion: Overall, SpHb by Masimo Rad-67® Pulse CO-Oximeter® did not accurately identify pregnant women with anemia and many cases would be missed. We would not recommend its use in antenatal care settings.</p
The chronotron: a neuron that learns to fire temporally-precise spike patterns
No full textIn many cases, neurons process information carried by the precise timing of spikes. Here we show how neurons can learn to generate specific temporally-precise output spikes in response to input spike patterns, thus processing and memorizing information that is fully temporally coded, both as input and as output. We introduce two new supervised learning rules for spiking neurons with temporal coding of information (chronotrons), one that is analytically-derived and highly efficient, and one that has a high degree of biological plausibility. We show how chronotrons can learn to classify their inputs and we study their memory capacity
Harnessing the PRECISE network as a platform to strengthen global capacity for maternal and child health research in sub-Saharan Africa
No full textIt is widely acknowledged across the global health sector that research programmes need to be designed and implemented in a way that maximise opportunities for strengthening local capacity. This paper examines how the United Kingdom Research and Innovation (UKRI) Grand Challenges Research Fund (GCRF) funded PRECISE (PREgnancy Care Integrating translational Science, Everywhere) Network has been established as a platform to strengthen global capacity for research focused on the improvement of maternal, fetal and newborn health in subSaharan Africa. Best practice principles outlined in an ESSENCE on Health Research report have been considered in relation to the PRECISE Network capacity-building activities described in this paper. These activities are described at the individual, programmatic and institutional levels, and successes, challenges and recommendations for future work are outlined. The paper concludes that the PRECISE leadership have an opportunity to review and refresh activity plans for capacity building at this stage in the project to build on achievements to date
Pregnancy cohorts and biobanking in sub-Saharan Africa : a systematic review
No full textBackground Technological advances and high throughput biological assays can facilitate discovery science in biobanks from population cohorts, including pregnant women. Biological pathways associated with health outcomes differ depending on geography, and high-income country data may not generalise to low-resource settings. We conducted a systematic review to identify prospective pregnancy cohorts in sub-Saharan Africa (SSA) that include biobanked samples with potential to enhance discovery science opportunity. Methods Inclusion criteria were prospective data collection during pregnancy, with associated biobanking in SSA. Data sources included: scientific databases (with comprehensive search terms), grey literature, hand searching applicable reference lists and expert input. Results were screened in a three-stage process based on title, abstract and full text by two independent reviewers. The review is registered on PROSPERO (CRD42019147483). Results Fourteen SSA studies met the inclusion criteria from database searches (n=8), reference list searches (n=2) and expert input (n=4). Three studies have ongoing data collection. The most represented countries were South Africa and Mozambique (Southern Africa) (n=3), Benin (Western Africa) (n=4) and Tanzania (Eastern Africa) (n=4); including an estimated 31 763 women. Samples commonly collected were blood, cord blood and placenta. Seven studies collected neonatal samples. Common clinical outcomes included maternal and perinatal mortality, malaria and preterm birth. Conclusions Increasingly numerous pregnancy cohorts in SSA that include biobanking are generating a uniquely valuable resource for collaborative discovery science, and improved understanding of the high regional risks of maternal, fetal and neonatal morbidity and mortality. Future studies should align protocols and consider their added value and distinct contributions
Precise relative clock synchronization for distributed control using TSC registers
No full textPrecise clock synchronization is essential in emerging time-critical distributed control systems operating over computer networks where the clock synchronization requirements are mostly focused on relative clock synchronization and high synchronization precision. Existing clock synchronization techniques such as the Network Time Protocol (NTP) and the IEEE 1588 standard can be difficult to apply to such systems because of the highly precise hardware clocks required, due to network congestion caused by a high frequency of synchronization message transmissions, and high overheads. In response, we present a Time Stamp Counter based precise Relative Clock Synchronization Protocol (TSC-RCSP) for distributed control applications operating over local-area networks (LANs). In our protocol a software clock based on the TSC register, counting CPU cycles, is adopted in the time clients and server. TSC-based clocks offer clients a precise, stable and low-cost clock synchronization solution. Experimental results show that clock precision in the order of 10~microseconds can be achieved in small-scale LAN systems. Such clock precision is much higher than that of a processor's Time-Of-Day clock, and is easily sufficient for most distributed real-time control applications over LANs
Towards Precise Network Measurements
No full textThis dissertation investigates the question: How do we precisely access and control time in a network of computer systems? Time is fundamental for network measurements. It is fundamental in measuring one-way delay and round trip times, which are important for network research, monitoring, and applications. Further, measuring such metrics requires precise timestamps, control of time gaps between messages and synchronized clocks. However, as the speed of computer networks increase and processing delays of network devices decrease, it is challenging to perform network measurements precisely.
The key approach that this dissertation explores to controlling time and achieving precise network measurements is to use the physical layer of the network stack. It allows the exploitation of two observations: First, when two physical layers are connected via a cable, each physical layer always generates either data or special characters to maintain the link connectivity. Second, such continuous generation allows two physical layers to be synchronized for clock and bit recovery. As a result, the precision of timestamping can be improved by counting the number of special characters between messages in the physical layer. Further, the precision of pacing can be improved by controlling the number of special characters between messages in the physical layer. Moreover, the precision of synchronized clocks can be improved by running a protocol inside the physical layer by extending bit-level synchronization.
Subsequently, we make three contributions embodied in the design, implementation and evaluation of our approaches. First, we present how to improve the precision of timestamping and pacing via access to the physical layer at sub-nanosecond scale. SoNIC implements the physical layer in software and allows users to control and access every bit in the physical layer. Second, we demonstrate that precise timestamping and pacing can improve the performance of network applications with two examples: Covert timing channels and available bandwidth estimation. A covert timing channel, Chupja, is high-bandwidth and robust and can deliver hidden messages while avoiding detection. An available bandwidth estimation algorithm, MinProbe, can accurately estimate the available bandwidth in a high-speed network. Finally, we present how to improve the precision of synchronized clocks via access to the physical layer. DTP, Datacenter Time Protocol, extends the physical layer's link-level synchronization and implements a peer-to-peer clock synchronization protocol with bounded nanosecond precision. Together, these systems and approaches represent important steps towards precise network measurements
Precise leveling network analysis by graphic chart
No full textRelative measurements made between any pair of Benchmarks (PB1 and PB2) in a precise leveling network often involves at least one forward and one backward observation in a PB1→PB2, PB2→PB1 sequence respectively. However, due to fatigue on the part of the surveyors and field assistants, hazards along geodetic survey routes and some times attempt to reduce financial cost of field surveys, observations made in one direction and are assumed to be adequate for both ties (fore and back).This is a technical bias or constraint imposed on the network, which will surely result in a weak, poor and deficient control of measurements in the network. To ensure completeness and geometrical strength and reliability in a survey network, analysis by graphic chart is relevant. This paper used graphic chart technique to analyse and evaluate the completeness, homogeneity and symmetry of a precise leveling network over part of Samaru Campus of Ahmadu Bello University, Zaria. The results show about 62% completeness, absolute homogeneity (H=0) and absolute symmetry (100%). It is recommended that network analysis for all precise leveling networks be carried out prior the rigorous adjustment computations in order to detect any missing links and ties in the network and to improve the network reliability and accuracy. Engineering and applied science problems that require a two-way measurement or feedback system could benefit tremendously from this technique.Keywords: Precise leveling, network, graphic chart, analysi
A survey on intelligent sensor network and its applications
No full textWith advances in technology, small form-factor sensors are feasible for various kinds of applications. The improvements on communication technology further make it practical to construct a wireless sensor network (WSN). In this paper, we review the works that are related to intelligent sensor network. Because there are no precise definitions of intelligent sensor network, we group them into two categories. One is to solve WSN issues with intelligent algorithms. The other is to design an intelligent application that incorporates sensor networks as the data sources. According to the categorization, the description of WSN issues, intelligent algorithms, and intelligent application technology are also provided in this article.補正完
The determination of subtle deformation signals using a permanent CGPS network in the Aegean
No full textGeophysical motions can occur over a broad temporal spectrum, from high frequency seismic movements to very long period tectonic deformation. The Aegean region is tectonically one of the most active areas on Earth. There have, over the past 15 years, been a range of campaign style GPS studies which have looked to increase our knowledge of the area and better define the geodynamic processes involved. In 2002 the Center for the Observation and Modelling of Earthquakes and Tectonics (COMET) established a network of continuously operating GPS receivers (CGPS) throughout the region in order to add to the knowledge gained from previous studies.
This thesis focuses on which tectonic motions can be observed using the COMET continuous GPS network. Approaches for the precise analytical estimation of subtle tectonic motion are presented. Daily coordinate estimates of COMET sites and a number of ITRF (International Terrestrial Reference Frame) sites around Europe were calculated using a precise point positioning strategy and ambiguity resolution using NASA’s GIPSY – OASIS II processing software and IGS (International GPS Service) precise products. Time series produced showed post fit standard deviations of 2-3 mm in the horizontal and 6-8 mm in the vertical. Significant annual periodic variation is observed in the time series.
The coordinate time series studies were further refined using a selection of filters. Firstly, gross and sigma filters were applied to remove outliers, the data then had a range of regional filters applied looking to best define and remove the common mode error in the area. These filters produced mixed results with time series improvement occurring on a site by site basis. In some cases noise was reduced by a factor of 2 whilst in other cases there was little or no improvement. This combined with a lack of knowledge of the individual site movements led to the use of a filtered baseline method, whereby common mode error was removed purely on a site by site basis. This method revealed expansion across the Hellenic arc of the order of a few millimetres per year and sub millimetre north-south compaction behind the arc. It also revealed first evidence of transient motion at a number of sites parallel to the Hellenic arc. The transient signals occurred every 12 months ±1.5 and lasting for 40 – 100 days. These signals were not so much a reversal of tectonic motion akin to the silent earthquakes observed in Cascadia, Japan and Mexico, instead they appeared more as a pause in the otherwise consistent movement of the Aegean microplate overriding the subducting African lithosphere. In addition to the observed tectonic signals, the effects and implications of the two post processing strategies are analysed and discussed.
Higher temporal frequency positioning is carried out on seismic events (Mw 6.7 earthquake Kithera, Mw 8.1 and Mw 6.7 earthquakes, Macquarie island) using instantaneous positioning followed by “sidereal filtering” whereby integer-cycle phase ambiguities are resolved using only single epochs of dual frequency phase and pseudorange data. These positions are then siderealy stacked to reduce the effects of geometry related error. The technique reduces geometry related noise by a factor ≈2 using epoch by epoch 30 second data. The feasibility of the technique for observing pre, co and post seismic signals is demonstrated.
A visualisation tool was developed to allow the simultaneous observation of the tectonic motion of a CGPS network data over any spatial and temporal regimes
Acceptability and Feasibility of a Low-Cost Device for Gestational Age Assessment in a Low-Resource Setting: Qualitative Study
No full textBackground: Ultrasound for gestational age (GA) assessment is not routinely available in resource-constrained settings, particularly in rural and remote locations. The TraCer device combines a handheld wireless ultrasound probe and a tablet with artificial intelligence (AI)-enabled software that obtains GA from videos of the fetal head by automated measurements of the fetal transcerebellar diameter and head circumference.
Objective: The aim of this study was to assess the perceptions of pregnant women, their families, and health care workers regarding the feasibility and acceptability of the TraCer device in an appropriate setting.
Methods: A descriptive study using qualitative methods was conducted in two public health facilities in Kilifi county in coastal Kenya prior to introduction of the new technology. Study participants were shown a video role-play of the use of TraCer at a typical antenatal clinic visit. Data were collected through 6 focus group discussions (N=52) and 18 in-depth interviews.
Results: Overall, TraCer was found to be highly acceptable to women, their families, and health care workers, and its implementation at health care facilities was considered to be feasible. Its introduction was predicted to reduce anxiety regarding fetal well-being, increase antenatal care attendance, increase confidence by women in their care providers, as well as save time and cost by reducing unnecessary referrals. TraCer was felt to increase the self-image of health care workers and reduce time spent providing antenatal care. Some participants expressed hesitancy toward the new technology, indicating the need to test its performance over time before full acceptance by some users. The preferred cadre of health care professionals to use the device were antenatal clinic nurses. Important implementation considerations included adequate staff training and the need to ensure sustainability and consistency of the service. Misconceptions were common, with a tendency to overestimate the diagnostic capability, and expectations that it would provide complete reassurance of fetal and maternal well-being and not primarily the GA.
Conclusions: This study shows a positive attitude toward TraCer and highlights the potential role of this innovation that uses AI-enabled automation to assess GA. Clarity of messaging about the tool and its role in pregnancy is essential to address misconceptions and prevent misuse. Further research on clinical validation and related usability and safety evaluations are recommended
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