Dual solid cryogens for spacecraft refrigeration Patent

Dual solid cryogens for spacecraft refrigeration insuring low temperature cooling for extended period

Design and construction of an engineering model solid cryogen refrigerator for infrared detector cooling at 50 deg K

Design and construction of prototype spacecraft cryogenic refrigerator for infrared detector coolin

Development of dual solid cryogens for high reliability refrigeration system

High reliability solid cryogen refrigeration system consists of a container initially filled with a solid cryogen which is coupled thermally to an infrared detector by means of a link of high thermal conductivity extending from a heat exchanger within the cryogen container

Clustering of Socioeconomic, Behavioural, and Neonatal Risk Factors for Infant Health in Pregnant Smokers

Background: Tobacco smoking is a major cause of morbidity and mortality, including during pregnancy. Although effective ways of promoting smoking cessation during pregnancy exist, the impact of these interventions has not been studied at a national level. We estimated the prevalence of smoking throughout pregnancy in the Netherlands and quantified associations of maternal smoking throughout pregnancy with socioeconomic, behavioural, and neonatal risk factors for infant health and development. Methodology/Principal Findings: Data of five national surveys, containing records of 14,553 Dutch mothers and their offspring were analyzed. From 2001 to 2007, the overall rate of smoking throughout pregnancy fell by 42% (from 13. 2% to 7. 6%) mainly as a result of a decrease among highly educated women. In the lowest-educated group, the overall rate of smoking throughout pregnancy was six times as high as in the highest-educated group (18. 7% versus 3. 2%). Prenatal tobacco smoke exposure was associated with increased risk of extremely preterm (≤28 completed weeks) (OR 7. 25; 95% CI 3. 40 to 15. 38) and small-for-gestational age (SGA) infants (OR 3. 08; 95% CI 2. 66 to 3. 57). Smoking-attributable risk percents in the population (based on adjusted risk ratios) were estimated at 29% for extremely preterm births and at 17% for SGA outcomes. Infants of smokers were more likely to experience significant alcohol exposure in utero (OR 2. 08; 95%CI 1. 25 to 3. 45) and formula feeding in early life (OR 1. 91; 95% CI 1. 69 to 2. 16). Conclusions: The rates of maternal smoking throughout pregnancy decreased significantly in the Netherlands from 2001 to 2007. If pregnant women were to cease tobacco use completely, an estimated 29% of extremely preterm births and 17% of SGA infants may be avoided annually. © 2009 Lanting et al

Effects of spatial dispersion in near-field radiative heat transfer between two parallel metallic surfaces

We study the heat transfer between two parallel metallic semi-infinite media with a gap in the nanometer-scale range. We show that the near-field radiative heat flux saturates at distances smaller than the metal skin depth when using a local dielectric constant and investigate the origin of this effect. The effect of non-local corrections is analysed using the Lindhard-Mermin and Boltzmann-Mermin models. We find that local and non-local models yield the same heat fluxes for gaps larger than 2 nm. Finally, we explain the saturation observed in a recent experiment as a manifestation of the skin depth and show that heat is mainly dissipated by eddy currents in metallic bodies.Comment: Version without figures (8 figures in the complete version

Impact of Vitamin C on Endothelial Function and Exercise Capacity in Patients with a Fontan Circulation

Objective.  To evaluate the impact of antioxidant therapy on functional health status in Fontan‐palliated patients. Design.  Prospective, randomized, double‐blind, placebo‐controlled trial. Patients.  Fifty‐three generally asymptomatic Fontan patients. Interventions.  Patients were randomized to receive either high‐dose ascorbic acid (vitamin C) or placebo for 4 weeks. Outcome Measures.  Peripheral vascular function, as measured with endothelium‐dependent digital pulse amplitude testing (EndoPAT), and exercise capacity were assessed before and after study drug treatment. Primary outcome measures included the EndoPAT index and peripheral arterial tonometry (PAT) ratio, both validated markers of vascular function. Secondary outcome measures included peak oxygen consumption and work. Results.  Twenty‐three vitamin C‐ and 21 placebo‐assigned subjects completed the protocol (83%). Median age and time from Fontan completion were 15 (interquartile range [IQR] 11.7–18.2) and 11.9 years (IQR 9.0–15.7), respectively. Right ventricular morphology was dominant in 30 (57%). Outcome measures were similar between groups at baseline. Among all subjects, vitamin C therapy was not associated with a statistical improvement in either primary or secondary outcome measures. In subjects with abnormal vascular function at baseline, compared with placebo, vitamin C therapy more frequently resulted in normalization of the EndoPAT index (45% vs. 17%) and PAT ratio (38% vs. 13%). Conclusions.  Short‐term therapy with vitamin C does not alter endothelial function or exercise capacity in an asymptomatic Fontan population overall. Vitamin C may provide benefit to a subset of Fontan patients with abnormal vascular function.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92126/1/j.1747-0803.2011.00605.x.pd

Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

We revisit the electromagnetic heat transfer between a metallic nanoparticle and a metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.Comment: publi\'e dans Physical Review B 77 (2008), version avant revie