2,325 research outputs found

    Interdigital Capacitance Local Non-Destructive Examination of Nuclear Power Plant Cable for Aging Management Programs

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    This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of non-destructive test methods focusing on local cable insulation and jacket testing using an interdigital capacitance (IDC) approach. Earlier studies have assessed a number of non-destructive examination (NDE) methods for bulk, distributed, and local cable tests. A typical test strategy is to perform bulk assessments of the cable response using dielectric spectroscopy, Tan , or partial discharge followed by distributed tests like time domain reflectometry or frequency domain reflectometry to identify the most likely defect location followed by a local test that can include visual inspection, indenter modulus tests, or Fourier Transform Infrared Spectroscopy (FTIR) or Near Infrared Spectroscopy FTIR (FTNIR). If a cable is covered with an overlaying jacket, the jacket’s condition is likely to be more severely degraded than the underlying insulation. None of the above local test approaches can be used to evaluate insulation beneath a cable jacket. Since the jacket’s function is neither structural nor electrical, a degraded jacket may not have any significance regarding the cable’s performance or suitability for service. IDC measurements offer a promising alternative or complement to these local test approaches including the possibility to test insulation beneath an overlaying jacket

    Inter-digital capacitive sensor for evaluating cable jacket and insulation aging

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    An inter-digital capacitive (TDC) sensor has previously been used to measure dielectric properties of cable insulation polymer material when placed in direct contact with the insulation. Often cable insulation is covered by a polymer jacket. The dielectric properties of many cable jacket and insulation polymers are known to change due to thermal and radiation exposure-related damage. These dielectric properties frequently track with other measures of cable aging, such as tensile elongation-at-break and indenter modulus that have been broadly established as cable insulation polymer assessment methods. The external jacket of a cable is likely to have a different permittivity from the underlying insulation, and frequently the jacket material exhibits more severe damage than the insulation material due to environmental exposure. Because the jacket serves primarily to guard the cable during installation, as long as the underlying insulation condition is acceptable, the jacket condition is relatively unimportant in service. As part of a continuing program to develop and evaluate nondestructive examination methods that may be applied to cable condition assessment, a set of tools has been developed including (1) a parallel-plate sensor to directly measure the permittivity spectrum of flat sheet material and (2) an TDC and fixture to measure the effect of cable polymer dielectric property change on the sensor response. The TDC consists of two fork-like electrodes facing each other with the fork tines interspersed and separated by a small gap. The electrodes are printed on one side of a flexible substrate that can be conformed to the surface of a cylindrical cable, with tines parallel to the cable axis. The electrodes are connected to a broad-frequency-spectral impedance meter that senses the capacitance between the narrowly gapped electrode tines. This capacitance is known to vary as a function of the permittivity of any material in close proximity to the electrodes. By finite element modeling (FEM) and experimentation, this study investigates the effect of tine spacing and other design parameters associated with the TDC on the voltage (potential) distribution and electric field depth of penetration. The TDC measurement of an unshielded ethylene-propylene rubber (EPR)-insulated cable is shown to track with the degree of aging and quantities obtained by established methods. For jacketed cable systems, the TDC response is dominated by the jacket but, by analyzing measurements from TDC sensors with different depths-of-field penetration into the cable under test, the influence of the chlorinated polyethylene (CPE) cable jacket material degradation can be separated from an assessment of the cable insulation thereby enabling assessment of the insulation beneath/through the jacket

    Neutral Silicon Vacancy Centers in Diamond via Photoactivated Itinerant Carriers

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    Neutral silicon vacancy (SiV0) centers in diamond are promising candidates for quantum network applications because of their exceptional optical properties and spin coherence. However, the stabilization of SiV0 centers requires careful Fermi level engineering of the diamond host material, making further technological development challenging. Here, we show that SiV0 centers can be efficiently stabilized by photoactivated itinerant carriers. Even in this nonequilibrium configuration, the resulting SiV0 centers are stable enough to allow for resonant optical excitation and optically detected magnetic resonance. Our results pave the way for on-demand generation of SiV0 centers as well as other emerging quantum defects in diamond

    Transport behavior of holes in boron delta-doped diamond structures

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    Boron delta-doped diamond structures have been synthesized using microwave plasma chemical vapor deposition and fabricated into FET and gated Hall bar devices for assessment of the electrical characteristics. A detailed study of variable temperature Hall, conductivity, and field-effect mobility measurements was completed. This was supported by Schr€dinger-Poisson and relaxation time o calculations based upon application of Fermi’s golden rule. A two carrier-type model was developed with an activation energy of 0.2eVbetweenthedeltalayerlowestsubbandwithmobility0.2 eV between the delta layer lowest subband with mobility 1 cm2/Vs and the bulk valence band with high mobility. This new understanding of the transport of holes in such boron delta-doped structures has shown that although Hall mobility as high as 900 cm2/Vs was measured at room temperature, this dramatically overstates the actual useful performance of the device

    Neutral silicon vacancy centers in undoped diamond via surface control

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    Neutral silicon vacancy centers (SiV0) in diamond are promising candidates for quantum networks because of their long spin coherence times and stable, narrow optical transitions. However, stabilizing SiV0 requires high purity, boron doped diamond, which is not a readily available material. Here, we demonstrate an alternative approach via chemical control of the diamond surface. We use low-damage chemical processing and annealing in a hydrogen environment to realize reversible and highly stable charge state tuning in undoped diamond. The resulting SiV0 centers display optically detected magnetic resonance and bulk-like optical properties. Controlling the charge state tuning via surface termination offers a route for scalable technologies based on SiV0 centers, as well as charge state engineering of other defects

    The effects of vitamin K-rich green leafy vegetables on bone metabolism: a 4-week randomised controlled trial in middle-aged and older individuals

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    Background: High vegetable intake is associated with beneficial effects on bone. However, the mechanisms remain uncertain. Green leafy vegetables are a rich source of vitamin K1, which is known to have large effects on osteoblasts and osteocalcin (OC) metabolism. Objective: To examine the effects of consumption of two to three extra serves of green leafy vegetables daily on bone metabolism. Methods: Thirty individuals (mean age 61.8 ± 9.9 years, 67% male) completed three experimental phases in a randomised controlled crossover design, each lasting four weeks, with a washout period of four weeks between phases (clinical trial registration: ACTRN12615000194561). The three experimental phases were: (i) increased dietary vitamin K1 by consuming green leafy vegetables (H-K, ~200 g/d containing 164.3 [99.5–384.7] μg/d of vitamin K1), (ii) low vitamin K1 by consuming vitamin K1-poor vegetables (L-K, ~200 g/d containing 9.4 [7.7–11.6] μg/d of vitamin K1), and (iii) control (CON) where participants consumed an energy-matched non-vegetable control. OC forms, total OC (tOC), carboxylated OC (cOC) and undercarboxylated OC (ucOC), were measured in serum pre- and post-intervention for each experimental phase using a sandwich-electrochemiluminescence immunoassay. Results: Pre-intervention tOC, ucOC and ucOC:tOC levels were similar between phases (P \u3e .05). Following H-K, but not L-K, tOC, ucOC and ucOC:tOC levels were significantly lower compared to pre-intervention levels (P ≤ .001) and compared to CON (~14%, 31% and 19%, respectively, all P \u3c .05), while cOC remained unchanged. Conclusions: In middle-aged healthy men and women, an easily achieved increase in dietary intake of vitamin K1-rich green leafy vegetables substantially reduces serum tOC and ucOC suggesting increased entry of OC into bone matrix, where it may improve the material property of bone. In conjunction with previous epidemiological and randomised controlled trial data, these findings suggest that interventions to increase vegetable intake over extended periods should include bone end points including fracture risk

    Hyperfine Spectroscopy of Isotopically Engineered Group-IV Color Centers in Diamond

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    A quantum register coupled to a spin-photon interface is a key component in quantum communication and information processing. Group-IV color centers in diamond (SiV, GeV, and SnV) are promising candidates for this application, comprising an electronic spin with optical transitions coupled to a nuclear spin as the quantum register. However, the creation of a quantum register for these color centers with deterministic and strong coupling to the spin-photon interface remains challenging. Here, we make first-principles predictions of the hyperfine parameters of the group-IV color centers, which we verify experimentally with a comprehensive comparison between the spectra of spin active and spin neutral intrinsic dopant nuclei in single GeV and SnV emitters. In line with the theoretical predictions, detailed spectroscopy on large sample sizes reveals that hyperfine coupling causes a splitting of the optical transition of SnV an order of magnitude larger than the optical linewidth and provides a magnetic-field insensitive transition. This strong coupling provides access to a new regime for quantum registers in diamond color centers, opening avenues for novel spin-photon entanglement and quantum sensing schemes for these well-studied emitters

    Targeted client communication via mobile devices for improving maternal, neonatal, and child health.

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    BACKGROUND: The global burden of poor maternal, neonatal, and child health (MNCH) accounts for more than a quarter of healthy years of life lost worldwide. Targeted client communication (TCC) via mobile devices (MD) (TCCMD) may be a useful strategy to improve MNCH. OBJECTIVES: To assess the effects of TCC via MD on health behaviour, service use, health, and well-being for MNCH. SEARCH METHODS: In July/August 2017, we searched five databases including The Cochrane Central Register of Controlled Trials, MEDLINE and Embase. We also searched two trial registries. A search update was carried out in July 2019 and potentially relevant studies are awaiting classification. SELECTION CRITERIA: We included randomised controlled trials that assessed TCC via MD to improve MNCH behaviour, service use, health, and well-being. Eligible comparators were usual care/no intervention, non-digital TCC, and digital non-targeted client communication. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane, although data extraction and risk of bias assessments were carried out by one person only and cross-checked by a second. MAIN RESULTS: We included 27 trials (17,463 participants). Trial populations were: pregnant and postpartum women (11 trials conducted in low-, middle- or high-income countries (LMHIC); pregnant and postpartum women living with HIV (three trials carried out in one lower middle-income country); and parents of children under the age of five years (13 trials conducted in LMHIC). Most interventions (18) were delivered via text messages alone, one was delivered through voice calls only, and the rest were delivered through combinations of different communication channels, such as multimedia messages and voice calls. Pregnant and postpartum women TCCMD versus standard care For behaviours, TCCMD may increase exclusive breastfeeding in settings where rates of exclusive breastfeeding are less common (risk ratio (RR) 1.30, 95% confidence intervals (CI) 1.06 to 1.59; low-certainty evidence), but have little or no effect in settings where almost all women breastfeed (low-certainty evidence). For use of health services, TCCMD may increase antenatal appointment attendance (odds ratio (OR) 1.54, 95% CI 0.80 to 2.96; low-certainty evidence); however, the CI encompasses both benefit and harm. The intervention may increase skilled attendants at birth in settings where a lack of skilled attendants at birth is common (though this differed by urban/rural residence), but may make no difference in settings where almost all women already have a skilled attendant at birth (OR 1.00, 95% CI 0.34 to 2.94; low-certainty evidence). There were uncertain effects on maternal and neonatal mortality and morbidity because the certainty of the evidence was assessed as very low. TCCMD versus non-digital TCC (e.g. pamphlets) TCCMD may have little or no effect on exclusive breastfeeding (RR 0.92, 95% CI 0.79 to 1.07; low-certainty evidence). TCCMD may reduce 'any maternal health problem' (RR 0.19, 95% CI 0.04 to 0.79) and 'any newborn health problem' (RR 0.52, 95% CI 0.25 to 1.06) reported up to 10 days postpartum (low-certainty evidence), though the CI for the latter includes benefit and harm. The effect on health service use is unknown due to a lack of studies. TCCMD versus digital non-targeted communication No studies reported behavioural, health, or well-being outcomes for this comparison. For use of health services, there are uncertain effects for the presence of a skilled attendant at birth due to very low-certainty evidence, and the intervention may make little or no difference to attendance for antenatal influenza vaccination (RR 1.05, 95% CI 0.71 to 1.58), though the CI encompasses both benefit and harm (low-certainty evidence). Pregnant and postpartum women living with HIV TCCMD versus standard care For behaviours, TCCMD may make little or no difference to maternal and infant adherence to antiretroviral (ARV) therapy (low-certainty evidence). For health service use, TCC mobile telephone reminders may increase use of antenatal care slightly (mean difference (MD) 1.5, 95% CI -0.36 to 3.36; low-certainty evidence). The effect on the proportion of births occurring in a health facility is uncertain due to very low-certainty evidence. For health and well-being outcomes, there was an uncertain intervention effect on neonatal death or stillbirth, and infant HIV due to very low-certainty evidence. No studies reported on maternal mortality or morbidity. TCCMD versus non-digital TCC The effect is unknown due to lack of studies reporting this comparison. TCCMD versus digital non-targeted communication TCCMD may increase infant ARV/prevention of mother-to-child transmission treatment adherence (RR 1.26, 95% CI 1.07 to 1.48; low-certainty evidence). The effect on other outcomes is unknown due to lack of studies. Parents of children aged less than five years No studies reported on correct treatment, nutritional, or health outcomes. TCCMD versus standard care Based on 10 trials, TCCMD may modestly increase health service use (vaccinations and HIV care) (RR 1.21, 95% CI 1.08 to 1.34; low-certainty evidence); however, the effect estimates varied widely between studies. TCCMD versus non-digital TCC TCCMD may increase attendance for vaccinations (RR 1.13, 95% CI 1.00 to 1.28; low-certainty evidence), and may make little or no difference to oral hygiene practices (low-certainty evidence). TCCMD versus digital non-targeted communication TCCMD may reduce attendance for vaccinations, but the CI encompasses both benefit and harm (RR 0.63, 95% CI 0.33 to 1.20; low-certainty evidence). No trials in any population reported data on unintended consequences. AUTHORS' CONCLUSIONS: The effect of TCCMD for most outcomes is uncertain. There may be improvements for some outcomes using targeted communication but these findings were of low certainty. High-quality, adequately powered trials and cost-effectiveness analyses are required to reliably ascertain the effects and relative benefits of TCCMD. Future studies should measure potential unintended consequences, such as partner violence or breaches of confidentiality

    Targeted client communication via mobile devices for improving sexual and reproductive health.

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    BACKGROUND: The burden of poor sexual and reproductive health (SRH) worldwide is substantial, disproportionately affecting those living in low- and middle-income countries. Targeted client communication (TCC) delivered via mobile devices (MD) (TCCMD) may improve the health behaviours and service use important for sexual and reproductive health. OBJECTIVES: To assess the effects of TCC via MD on adolescents' knowledge, and on adolescents' and adults' sexual and reproductive health behaviour, health service use, and health and well-being. SEARCH METHODS: In July/August 2017, we searched five databases including The Cochrane Central Register of Controlled Trials, MEDLINE and Embase. We also searched two trial registries. A search update was carried out in July 2019 and potentially relevant studies are awaiting classification. SELECTION CRITERIA: We included randomised controlled trials of TCC via MD to improve sexual and reproductive health behaviour, health service use, and health and well-being. Eligible comparators were standard care or no intervention, non-digital TCC, and digital non-targeted communication. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane, although data extraction and risk of bias assessments were carried out by one person only and cross-checked by a second. We have presented results separately for adult and adolescent populations, and for each comparison. MAIN RESULTS: We included 40 trials (27 among adult populations and 13 among adolescent populations) with a total of 26,854 participants. All but one of the trials among adolescent populations were conducted in high-income countries. Trials among adult populations were conducted in a range of high- to low-income countries. Among adolescents, nine interventions were delivered solely through text messages; four interventions tested text messages in combination with another communication channel, such as emails, multimedia messaging, or voice calls; and one intervention used voice calls alone. Among adults, 20 interventions were delivered through text messages; two through a combination of text messages and voice calls; and the rest were delivered through other channels such as voice calls, multimedia messaging, interactive voice response, and instant messaging services. Adolescent populations TCCMD versus standard care TCCMD may increase sexual health knowledge (risk ratio (RR) 1.45, 95% confidence interval (CI) 1.23 to 1.71; low-certainty evidence). TCCMD may modestly increase contraception use (RR 1.19, 95% CI 1.05 to 1.35; low-certainty evidence). The effects on condom use, antiretroviral therapy (ART) adherence, and health service use are uncertain due to very low-certainty evidence. The effects on abortion and STI rates are unknown due to lack of studies. TCCMD versus non-digital TCC (e.g. pamphlets) The effects of TCCMD on behaviour (contraception use, condom use, ART adherence), service use, health and wellbeing (abortion and STI rates) are unknown due to lack of studies for this comparison. TCCMD versus digital non-targeted communication The effects on sexual health knowledge, condom and contraceptive use are uncertain due to very low-certainty evidence. Interventions may increase health service use (attendance for STI/HIV testing, RR 1.61, 95% CI 1.08 to 2.40; low-certainty evidence). The intervention may be beneficial for reducing STI rates (RR 0.61, 95% CI 0.28 to 1.33; low-certainty evidence), but the confidence interval encompasses both benefit and harm. The effects on abortion rates and on ART adherence are unknown due to lack of studies. We are uncertain whether TCCMD results in unintended consequences due to lack of evidence. Adult populations TCCMD versus standard care For health behaviours, TCCMD may modestly increase contraception use at 12 months (RR 1.17, 95% CI 0.92 to 1.48) and may reduce repeat abortion (RR 0.68 95% CI 0.28 to 1.66), though the confidence interval encompasses benefit and harm (low-certainty evidence). The effect on condom use is uncertain. No study measured the impact of this intervention on STI rates. TCCMD may modestly increase ART adherence (RR 1.13, 95% CI 0.97 to 1.32, low-certainty evidence, and standardised mean difference 0.44, 95% CI -0.14 to 1.02, low-certainty evidence). TCCMD may modestly increase health service utilisation (RR 1.17, 95% CI 1.04 to 1.31; low-certainty evidence), but there was substantial heterogeneity (I2 = 85%), with mixed results according to type of service utilisation (i.e. attendance for STI testing; HIV treatment; voluntary male medical circumcision (VMMC); VMMC post-operative visit; post-abortion care). For health and well-being outcomes, there may be little or no effect on CD4 count (mean difference 13.99, 95% CI -8.65 to 36.63; low-certainty evidence) and a slight reduction in virological failure (RR 0.86, 95% CI 0.73 to 1.01; low-certainty evidence). TCCMD versus non-digital TCC No studies reported STI rates, condom use, ART adherence, abortion rates, or contraceptive use as outcomes for this comparison. TCCMD may modestly increase in service attendance overall (RR: 1.12, 95% CI 0.92-1.35, low certainty evidence), however the confidence interval encompasses benefit and harm. TCCMD versus digital non-targeted communication No studies reported STI rates, condom use, ART adherence, abortion rates, or contraceptive use as outcomes for this comparison. TCCMD may increase service utilisation overall (RR: 1.71, 95% CI 0.67-4.38, low certainty evidence), however the confidence interval encompasses benefit and harm and there was considerable heterogeneity (I2 = 72%), with mixed results according to type of service utilisation (STI/HIV testing, and VMMC). Few studies reported on unintended consequences. One study reported that a participant withdrew from the intervention as they felt it compromised their undisclosed HIV status. AUTHORS' CONCLUSIONS: TCCMD may improve some outcomes but the evidence is of low certainty. The effect on most outcomes is uncertain/unknown due to very low certainty evidence or lack of evidence. High quality, adequately powered trials and cost effectiveness analyses are required to reliably ascertain the effects and relative benefits of TCC delivered by mobile devices. Given the sensitivity and stigma associated with sexual and reproductive health future studies should measure unintended consequences, such as partner violence or breaches of confidentiality
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