3,550 research outputs found
Measuring Access and Practice: Designing a Survey Methodology for the Hygiene, Sanitation and Water Sector
No full textAccess to safe water and sanitary means of excreta disposal are essential elements of
human development and poverty alleviation. It is estimated that one in four people in
the developing world lacks access to water while over half the population has no
access to sanitation. From the Alma-Ata declaration in 1978 to the recent Millennium
Development Goals, efforts to improve this situation have been hampered by the lack
of meaningful indicators to measure hygiene, sanitation and water coverage and
establish progress towards the goals and targets set out by the international
community.
This thesis aims to determine if measuring prevalence of access to water~ sanitation
and the practice of hygienic behaviour in hous~hold surveys can be.improved. With
no indicators available in current international' laws and targets, various aspects of
access and practice were examined to design indicators for field-testing. By using
- existing data sets, the research established that there is a high geographic clustering of
the measures of interest, which results in large design effects (deff) and rates of
homogeneity (roh) in cluster surveys. Based on the calculated roh optimum numbers
ofcluster and sample size were calculated for the field trials. This requires
introducing survey costs in the sample size calculations. The high clustering of water
and sanitation indicator require large sample sizes, resulting in large amounts of data
which organisations in the four field trials in Kosovo, South Africa, Kenya and Laos
found difficult to handle. Practical problems in the implementation of the survey
method resulted in non-sampling errors and could cause reluctance in adoption the
methodology. The research improved water and sanitation indicators but found that
for individual behaviour such as hygiene the household is not a suitable sampling unit.
It also showed that observation among interviewers have to be better standardised to
reduce the inter-surveyor.variation. Representative sampling is the current bottleneck
in the development of such a survey method. Current method requires a good
understanding of sampling theory as well as reliable sample frames, which are rarely
available to implementing organisations. Alternative sampling methods are
suggested, and recommendations are made for the further development ofthe survey
method designed in this research, which to date may be too complex for widespread
use
A novel design for an RF MEMS resistive switch on PCB substrate
No full textCopyright @ 2008 Stimulation Action on MEM
Safety, tolerability, and immunogenicity of influenza vaccination with a high-density microarray patch: Results from a randomized, controlled phase I clinical trial
No full textBackgroundThe Vaxxas high-density microarray patch (HD-MAP) consists of a high density of microprojections coated with vaccine for delivery into the skin. Microarray patches (MAPs) offer the possibility of improved vaccine thermostability as well as the potential to be safer, more acceptable, easier to use, and more cost-effective for the administration of vaccines than injection by needle and syringe (N&S). Here, we report a phase I trial using the Vaxxas HD-MAP to deliver a monovalent influenza vaccine that was to the best of our knowledge the first clinical trial to evaluate the safety, tolerability, and immunogenicity of lower doses of influenza vaccine delivered by MAPs.Methods and findingsHD-MAPs were coated with a monovalent, split inactivated influenza virus vaccine containing A/Singapore/GP1908/2015 H1N1 haemagglutinin (HA). Between February 2018 and March 2018, 60 healthy adults (age 18–35 years) in Melbourne, Australia were enrolled into part A of the study and vaccinated with either: HD-MAPs delivering 15 μg of A/Singapore/GP1908/2015 H1N1 HA antigen (A-Sing) to the volar forearm (FA); uncoated HD-MAPs; intramuscular (IM) injection of commercially available quadrivalent influenza vaccine (QIV) containing A/Singapore/GP1908/2015 H1N1 HA (15 μg/dose); or IM injection of H1N1 HA antigen (15 μg/dose). After 22 days’ follow-up and assessment of the safety data, a further 150 healthy adults were enrolled and randomly assigned to 1 of 9 treatment groups. Participants (20 per group) were vaccinated with HD-MAPs delivering doses of 15, 10, 5, 2.5, or 0 μg of HA to the FA or 15 μg HA to the upper arm (UA), or IM injection of QIV. The primary objectives of the study were safety and tolerability. Secondary objectives were to assess the immunogenicity of the influenza vaccine delivered by HD-MAP. Primary and secondary objectives were assessed for up to 60 days post-vaccination. Clinical staff and participants were blind as to which HD-MAP treatment was administered and to administration of IM-QIV-15 or IM-A/Sing-15. All laboratory investigators were blind to treatment and participant allocation. Two further groups in part B (5 participants per group), not included in the main safety and immunological analysis, received HD-MAPs delivering 15 μg HA or uncoated HD-MAPs applied to the forearm. Biopsies were taken on days 1 and 4 for analysis of the cellular composition from the HD-MAP application sites.The vaccine coated onto HD-MAPs was antigenically stable when stored at 40°C for at least 12 months. HD-MAP vaccination was safe and well tolerated; any systemic or local adverse events (AEs) were mild or moderate. Observed systemic AEs were mostly headache or myalgia, and local AEs were application-site reactions, usually erythema. HD-MAP administration of 2.5 μg HA induced haemagglutination inhibition (HAI) and microneutralisation (MN) titres that were not significantly different to those induced by 15 μg HA injected IM (IM-QIV-15). HD-MAP delivery resulted in enhanced humoral responses compared with IM injection with higher HAI geometric mean titres (GMTs) at day 8 in the MAP-UA-15 (GMT 242.5, 95% CI 133.2–441.5), MAP-FA-15 (GMT 218.6, 95% CI 111.9–427.0), and MAP-FA-10 (GMT 437.1, 95% CI 254.3–751.3) groups compared with IM-QIV-15 (GMT 82.8, 95% CI 42.4–161.8), p = 0.02, p = 0.04, p 0.001 for MAP-UA-15, MAP-FA-15, and MAP-FA-10, respectively. Higher titres were also observed at day 22 in the MAP-FA-10 (GMT 485.0, 95% CI 301.5–780.2, p = 0.001) and MAP-UA-15 (367.6, 95% CI 197.9–682.7, p = 0.02) groups compared with the IM-QIV-15 group (GMT 139.3, 95% CI 79.3–244.5). Results from a panel of exploratory immunoassays (antibody-dependent cellular cytotoxicity, CD4+ T-cell cytokine production, memory B cell (MBC) activation, and recognition of non-vaccine strains) indicated that, overall, Vaxxas HD-MAP delivery induced immune responses that were similar to, or higher than, those induced by IM injection of QIV. The small group sizes and use of a monovalent influenza vaccine were limitations of the study.ConclusionsInfluenza vaccine coated onto the HD-MAP was stable stored at temperatures up to 40°C. Vaccination using the HD-MAP was safe and well tolerated and resulted in immune responses that were similar to or significantly enhanced compared with IM injection. Using the HD-MAP, a 2.5 μg dose (1/6 of the standard dose) induced HAI and MN titres similar to those induced by 15 μg HA injected IM.Trial registrationAustralian New Zealand Clinical Trials Registry (ANZCTR.org.au), trial ID 108 ACTRN12618000112268/U1111-1207-3550.</div
The effect of intermittent antenatal iron supplementation on maternal and infant outcomes in rural Viet Nam: a cluster randomised trial
No full textBACKGROUND: Anemia affects over 500 million women, and in pregnancy is associated with impaired maternal and infant outcomes. Intermittent antenatal iron supplementation is an attractive alternative to daily dosing; however, the impact of this strategy on infant outcomes remains unclear. We compared the effect of intermittent antenatal iron supplementation with daily iron supplementation on maternal and infant outcomes in rural Viet Nam. METHODS AND FINDINGS: This cluster randomised trial was conducted in Ha Nam province, Viet Nam. 1,258 pregnant women (< 16 wk gestation) in 104 communes were assigned to daily iron-folic acid (IFA), twice weekly IFA, or twice weekly multiple micronutrient (MMN) supplementation. Primary outcome was birth weight. Mean birth weight was 3,148 g (standard deviation 416). There was no difference in the birth weights of infants of women receiving twice weekly IFA compared to daily IFA (mean difference [MD] 28 g; 95% CI -22 to 78), or twice weekly MMN compared to daily IFA (MD -36.8 g; 95% CI -82 to 8.2). At 32 wk gestation, maternal ferritin was lower in women receiving twice weekly IFA compared to daily IFA (geometric mean ratio 0.73; 95% CI 0.67 to 0.80), and in women receiving twice weekly MMN compared to daily IFA (geometric mean ratio 0.62; 95% CI 0.57 to 0.68), but there was no difference in hemoglobin levels. Infants of mothers who received twice weekly IFA had higher cognitive scores at 6 mo of age compared to those who received daily IFA (MD 1.89; 95% CI 0.23 to 3.56). CONCLUSIONS: Twice weekly antenatal IFA or MMN did not produce a clinically important difference in birth weight, when compared to daily IFA supplementation. The significant improvement in infant cognitive outcomes at 6 mo of age following twice weekly antenatal IFA requires further exploration, and provides additional support for the use of intermittent, rather than daily, antenatal IFA in populations with low rates of iron deficiency. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry 12610000944033
Effectiveness of a brief group behavioural intervention on psychological distress in young adolescent Syrian refugees: A randomised controlled trial
No full textBACKGROUND: Millions of young adolescents in low- and middle-income countries (LMICs) affected by humanitarian crises experience elevated rates of poor mental health. There is a need for scalable programs that can improve the mental health of young adolescents. This study evaluated the effectiveness of a nonspecialist delivered group-based intervention (Early Adolescent Skills for Emotions (EASE)) to improve young adolescents' mental health. METHODS AND FINDINGS: In this single-blind, parallel, controlled trial, Syrian refugees aged 10 to 14 years in Jordan were identified through screening of psychological distress as defined by scores ≥15 on the Paediatric Symptom Scale. Participants were randomised to either EASE or enhanced usual care (EUC) involving referral to local psychosocial services (on a 1:1.6 ratio). Participants were aware of treatment allocation but assessors were blinded. Primary outcomes were scores on the Paediatric Symptom Checklist (PSC; internalising, externalising, and attentional difficulty scales) assessed at week 0, 9 weeks, and 3 months after treatment (primary outcome time point). It was hypothesised that EASE would result in greater reductions on internalising symptoms than EUC. Secondary outcomes were depression, posttraumatic stress, well-being, functioning, school belongingness, and caregivers' parenting and mental health. Between June 2019 and January 2020, 1,842 young adolescent refugees were screened for eligibility on the basis of psychological distress. There were 520 adolescents (28.2%) who screened positive, of whom 471 (90.6%) agreed to enter the trial. Overall, 185 were assigned to EASE and 286 to EUC, and 169 and 254 were retained at 3 months for EASE and EUC, respectively. Intent-to-treat analyses indicated that at 3 months, EASE resulted in greater reduction on the PSC-internalising scale than EUC (estimated mean difference 0.69, 95% CI 0.19 to 1.19; p = 0.007; effect size, 0.38) but there were no differences for PSC-externalising (estimated mean difference 0.24, 95% CI -0.43 to 0.91; p = 0.49; effect size, -0.10), PSC-attentional problem (estimated mean difference -0.01, 95% CI -0.51 to 0.54; p = 0.97; effect size, -0.01) scores, or on depression, posttraumatic stress, well-being, functioning, or school belongingness. Relative to EUC, caregivers in EASE had less psychological distress (estimated mean difference 1.95, 95% CI 0.71 to 3.19; p = 0.002) and inconsistent disciplinary parenting (mean difference 1.54, 95% CI 1.03 to 2.05; p < 0.001). Secondary analyses that (a) focused on adolescents with probable internalising disorders; (b) completed the 3-month assessment; and (c) controlled for trauma exposure did not alter the primary results. Mediation analysis indicated that for caregivers in the EASE condition, reduction in inconsistent disciplinary parenting was associated with reduced attentional (β = 0.11, SE 0.07; 95% CI 0.003, 0.274) and internalising (β = 0.11, SE 0.07; 95% CI 0.003, 0.274) problems in their children. No adverse events were attributable to the intervention. A limitation was that EUC was not matched to EASE in terms of facilitator attention or group involvement. CONCLUSIONS: EASE led to reduced internalising problems in young refugee adolescents and was associated with reduced distress and less inconsistent disciplinary parenting in caregivers. This intervention has the potential as a scalable intervention to mitigate young adolescents' emotional difficulties in LMIC. TRIAL REGISTRATION: Prospectively registered at Australian and New Zealand Clinical Trials Registry: ACTRN12619000341123
Automated detection of prostate cancer using wavelet transform features of ultrasound RF time series
No full textThe aim of this research was to investigate the performance of wavelet transform based features of ultrasound radiofrequency (RF) time series for automated detection of prostate cancer tumors in transrectal ultrasound images. Sequential frames of RF echo signals from 35 extracted prostate specimens were recorded in parallel planes, while the ultrasound probe and the tissue were fixed in position in each imaging plane. The sequence of RF echo signal samples corresponding to a particular spot in tissue imaging plane constitutes one RF time series. Each region of interest (ROI) of ultrasound image was represented by three groups of features of its time series, namely, wavelet, spectral and fractal features. Wavelet transform approximation and detail sequences of each ROI were averaged and used as wavelet features. The average value of the normalized spectrum in four quarters of the frequency range along with the intercept and slope of a regression line fitted to the values of the spectrum versus normalized frequency plot formed six spectral features. Fractal dimension (FD) of the RF time series were computed based on the Higuchi's approach. A support vector machine (SVM) classifier was used to classify the ROIs. The results indicate that combining wavelet coefficient based features with previously proposed spectral and fractal features of RF time series data would increase the area under ROC curve from 93.1% to 95.0%, respectively. Furthermore, the accuracy, sensitivity, and specificity increases to 91.7%, 86.6%, and 94.7%, from 85.7%, 85.2%, and 86.1%, respectively, using only spectral and fractal features. [ABSTRACT FROM AUTHOR]Peer reviewedFinal article publishe
An RF-Powered DLL-Based 2.4-GHz Transmitter for Autonomous Wireless Sensor Nodes
No full textThis paper presents the system and circuit design of a compact radio frequency (RF)-powered 2.4-GHz CMOS transmitter (TX) to be used for autonomous wireless sensor nodes (WSNs). The proposed TX utilizes the received dedicated RF signal for both energy harvesting as well as frequency synthesis. A TX RF carrier is derived from the received RF signal by means of a delay locked loop and XOR-based frequency multiplier. The 50-Ω load is subsequently driven by a tuned switching RF power amplifier (PA) with 25% duty cycle input for high global efficiency. The design is fabricated in 40-nm CMOS technology and occupies a die area of 0.16 mm2. Experimental results show a rectifier with 36.83% peak efficiency and power management circuit with 120-nA current consumption that enables a low start-up power of -18.4 dBm. The TX outputs a continuous 2.44-GHz RF signal at -2.57 dBm with 36.5% PA drain efficiency and 23.9% global efficiency from a 915-MHz RF input and supports ON-OFF keying modulation.Accepted Author ManuscriptBio-Electronic
A Wideband 2x13-bit All-Digital I/Q RF-DAC
No full textThis paper presents a wideband 2 13-bit in-phase/quadrature-phase (I/Q) RF digital-to-analog converter-based all-digital modulator realized in 65-nm CMOS. The isolation between I and Q paths is guaranteed employing 25% duty-cycle differential quadrature clocks. With a 1.3-V supply and an on-chip power combiner, the digital I/Q transmitter provides more than 21-dBm RF output power within a frequency range of 1.36–2.51 GHz. The peak RF output power, overall system, and drain efficiencies of the modulator are 22.8 dBm, 34%, and 42%, respectively. The measured static noise floor is below 160 dBc/Hz. The digital I/Q RF modulator demonstrates an IQ image rejection and local oscillator leakage of 65 and 68 dBc, respectively. It could be linearized using either of the two digital predistortion (DPD) approaches: a memoryless polynomial or a lookup table. Its linearity is examined using single-carrier 4/16/64/256/1024 quadrature amplitude modulation (QAM), as well as multi-carrier 256-QAM orthogonal frequency-division multiplexing baseband signals while their related modulation bandwidth can be as high as 154 MHz. Employing DPD improves the third-order intermodulation product (IM3) by more than 25 dB, while the measured error vector magnitude for a “single-carrier 22-MHz 64-QAM” signal is better than 28 dB.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
Bracelet+: Harvesting the Leaked RF Energy in VLC with Wearable Bracelet Antenna
No full textVisible Light Communication (VLC) is widely considered a promising technology for the coming 6G networks. Recent studies show that a VLC transmitter not only emits visible light signals but also leaks RF signals during the transmission. In this work, we devote effort to harvesting the free leaked RF energy from VLC transmissions. We observe that the surrounding objects could help a coil antenna harvest significantly more RF energy. Based on this observation, we propose our system Bracelet+, which involves the human body in the harvesting system to increase the harvested power. After careful analysis of the influence of the human body on the harvested power, we prototype the coil antenna as a bracelet that achieves both high harvested power and convenience for wearing. The average power of the RF energy harvested by our design is 10 larger than that of the conventional coil antenna, without causing any interference to the communication of VLC systems. The harvested power can reach up to micro-watts in our tested scenarios. Such a micro-watt level of harvested energy has the potential to power up ultra-low-power sensors such as temperature sensors and glucose sensors.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Embedded System
Single Channel RF Signal Recovery for Nyquist Folding Receiver
No full textThis paper presents a method for exploiting wideband spectral information of real-valued radio frequency (RF) signals using the Nyquist Folding Receiver architecture. A new system model based on a symmetric modulation matrix is introduced so that the frequency band of the real input signals can be estimated without in-phase and quadrature reception and processing. To recover the original frequency of the input RF signal, we use the parameter-free sparse learning via iterative minimization (SLIM) method. Finally, the proposed model and the success of the recovery algorithm are demonstrated with data collected from an experimental testbed.Accepted Author ManuscriptMicrowave Sensing, Signals & System
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