33 research outputs found

    Microwave-induced nonequilibrium temperature in a suspended carbon nanotube

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    Antenna-coupled suspended single carbon nanotubes exposed to 108 GHz microwave radiation are shown to be selectively heated with respect to their metal contacts. This leads to an increase in the conductance as well as to the development of a power-dependent DC voltage. The increased conductance stems from the temperature dependence of tunneling into a one-dimensional electron system. The DC voltage is interpreted as a thermovoltage, due to the increased temperature of the electron liquid compared to the equilibrium temperature in the leads

    Critical-Current Reduction in Thin Superconducting Wires Due to Current Crowding

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    We demonstrate experimentally that the critical current in superconducting NbTiN wires is dependent on their geometrical shape, due to current-crowding effects. Geometric patterns such as 90 degree corners and sudden expansions of wire width are shown to result in the reduction of critical currents. The results are relevant for single-photon detectors as well as parametric amplifiers

    Needlestick injuries and infectious patients in a major academic medical centre from 2003 to 2010

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    To implement adequate preventive measures in a hospital, the number and nature of occupational exposures to blood must be known. In the Amsterdam Academic Medical Centre a standardised procedure was used to assess all reported occupational exposures to blood from 2003 to 2010. 1601 incidents were reported of which 66% were needlestick accidents. Thirty-five percent of the incidents concerned persons in training and 27% concerned experienced nurses. Twenty-nine percent of accidents occurred during cleaning up after a medical procedure, including the recapping of needles in 6%. In 8% of the accidents the patient was known or found to be infected with hepatitis B or C virus or HIV and in 86% of accidents the personnel were immune to HBV. One case of HCV transmission occurred. The number and nature of the occupational exposures indicate that preventive measures must focus on the replacement of needles by safety devices and on awareness training of experienced nurses and of persons in trainin

    Postnatal Nutrition to Improve Brain Development in the Preterm Infant : A Systematic Review From Bench to Bedside

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    Background: Preterm infants are at high risk for Encephalopathy of Prematurity and successive adverse neurodevelopmental outcome. Adequate nutrition is crucial for healthy brain development. Maternal breast milk is first choice of post-natal enteral nutrition for preterm infants. However, breast milk contains insufficient nutrient quantities to meet the greater nutritional needs of preterm infants, meaning that supplementation is recommended. Aim: To provide an overview of current literature on potential nutritional interventions for improvement of neurodevelopmental outcome in preterm infants, by taking a bench to bedside approach from pre-clinical models of neonatal brain injury to randomized controlled clinical trials (RCTs) in preterm infants. Methods: Separate clinical and pre-clinical searches were performed in Medline and Embase for English written papers published between 08/2008 and 08/2018 that studied a single nutritional component. Papers were included if one of the following components was studied: lipids, carbohydrates, proteins, vitamins, minerals, probiotics, prebiotics, oligosaccharides, fatty acids, or amino acids, with brain injury, brain development or neurodevelopmental outcome as outcome measure in preterm infants (gestational age <32 weeks and/or birth weight <1,500 g) or in animal models of neonatal brain injury. Results: In total, 2,671 pre-clinical studies and 852 RCTs were screened, of which 24 pre-clinical and 22 RCTs were included in this review. In these trials supplementation with amino acids and protein, lipids, probiotics (only clinical), prebiotics (only clinical), vitamins, and minerals was studied. All included pre-clinical studies show positive effect of supplementation on brain injury and/or neurodevelopment. Although some nutrients, such as glutamine, show promising short term outcome in clinical studies, no evident long term effect of any supplemented nutrient was found. Main limitations were inclusion of studies no older than 10 years at time of search and studies that focused on single nutritional components only. Conclusion: Even though many pre-clinical trials demonstrate promising effects of different nutritional interventions on reducing brain injury and/or improving neurodevelopmental outcome, these positive effects have so far not evidently been demonstrated in RCTs. More clinically relevant animal models and long term follow up after clinical trials are needed to move novel nutritional therapies from bench to bedside of preterm infants

    Postnatal nutrition to improve brain development in the preterm infant: A systematic review from bench to bedside

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    Background: Preterm infants are at high risk for Encephalopathy of Prematurity and successive adverse neurodevelopmental outcome. Adequate nutrition is crucial for healthy brain development. Maternal breast milk is first choice of post-natal enteral nutrition for preterm infants. However, breast milk contains insufficient nutrient quantities to meet the greater nutritional needs of preterm infants, meaning that supplementation is recommended. Aim: To provide an overview of current literature on potential nutritional interventions for improvement of neurodevelopmental outcome in preterm infants, by taking a bench to bedside approach from pre-clinical models of neonatal brain injury to randomized controlled clinical trials (RCTs) in preterm infants. Methods: Separate clinical and pre-clinical searches were performed in Medline and Embase for English written papers published between 08/2008 and 08/2018 that studied a single nutritional component. Papers were included if one of the following components was studied: lipids, carbohydrates, proteins, vitamins, minerals, probiotics, prebiotics, oligosaccharides, fatty acids, or amino acids, with brain injury, brain development or neurodevelopmental outcome as outcome measure in preterm infants (gestational age <32 weeks and/or birth weight <1,500 g) or in animal models of neonatal brain injury. Results: In total, 2,671 pre-clinical studies and 852 RCTs were screened, of which 24 pre-clinical and 22 RCTs were included in this review. In these trials supplementation with amino acids and protein, lipids, probiotics (only clinical), prebiotics (only clinical), vitamins, and minerals was studied. All included pre-clinical studies show positive effect of supplementation on brain injury and/or neurodevelopment. Although some nutrients, such as glutamine, show promising short term outcome in clinical studies, no evident long term effect of any supplemented nutrient was found. Main limitations were inclusion of studies no older than 10 years at time of search and studies that focused on single nutritional components only. Conclusion: Even though many pre-clinical trials demonstrate promising effects of different nutritional interventions on reducing brain injury and/or improving neurodevelopmental outcome, these positive effects have so far not evidently been demonstrated in RCTs. More clinically relevant animal models and long term follow up after clinical trials are needed to move novel nutritional therapies from bench to bedside of preterm infants

    Nutritional Intake, White Matter Integrity, and Neurodevelopment in Extremely Preterm Born Infants

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    Background: Determining optimal nutritional regimens in extremely preterm infants remains challenging. This study aimed to evaluate the effect of a new nutritional regimen and individual macronutrient intake on white matter integrity and neurodevelopmental outcome. Methods: Two retrospective cohorts of extremely preterm infants (gestational age &lt; 28 weeks) were included. Cohort B (n = 79) received a new nutritional regimen, with more rapidly increased, higher protein intake compared to cohort A (n = 99). Individual protein, lipid, and caloric intakes were calculated for the first 28 postnatal days. Diffusion tensor imaging was performed at term-equivalent age, and cognitive and motor development were evaluated at 2 years corrected age (CA) (Bayley-III-NL) and 5.9 years chronological age (WPPSI-III-NL, MABC-2-NL). Results: Compared to cohort A, infants in cohort B had significantly higher protein intake (3.4 g/kg/day vs. 2.7 g/kg/day) and higher fractional anisotropy (FA) in several white matter tracts but lower motor scores at 2 years CA (mean (SD) 103 (12) vs. 109 (12)). Higher protein intake was associated with higher FA and lower motor scores at 2 years CA (B = −6.7, p = 0.001). However, motor scores at 2 years CA were still within the normal range and differences were not sustained at 5.9 years. There were no significant associations with lipid or caloric intake. Conclusion: In extremely preterm born infants, postnatal protein intake seems important for white matter development but does not necessarily improve long-term cognitive and motor development
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