A Comparison of Energy Conversion Technologies for Space Nuclear Power Systems

A key element of space nuclear power systems is the energy conversion subsystem that converts the nuclear heat into electrical power. Nuclear systems provide a favorable option for missions that require long-duration power in hostile space environments where sunlight for solar power is absent or limited. There are two primary nuclear power technology options. Radioisotope Power System (RPS) utilize the natural decay heat from Pu238 to generate electric power levels up to about one kilowatt. Fission Power System (FPS) rely on a sustained fission reaction of U235 and offer the potential to supply electric power from kilowatts to megawatts. Example missions for nuclear power include Mars science rovers (e.g. Curiosity, Mars 2020), lunar and Mars surface landers ? including crewed missions, deep space planetary orbiters, Ocean World science landers, and robotic space probes that utilize nuclear electric propulsion. This paper examines the energy conversion technology options that can be used with RPS and FPS, and provides an assessment of their relative performance and technology readiness

What do people do with porn? qualitative research into the consumption, use and experience of pornography and other sexually explicit media

This article reviews qualitative research into the consumption of pornography and other sexually explicit media emerging from a range of subject areas. Taking a critique of quantitative methods and a focus on measuring sexual effects and attitudes as a starting point, it considers the proposition that qualitative work is more suited to an examination of the complex social, cultural and political constructions of sexuality. Examining studies into the way men, women and young people see, experience, and use explicit media texts, the article identifies the key findings that have emerged. Qualitative work shows that sexuality explicit media texts are experienced and understood in a variety of ways and evoke strong and often contradictory reactions, not all of which are represented in public debates about pornography. These texts function in a range of different ways, depending on context; as a source of knowledge, a resource for intimate practices, a site for identity construction, and an occasion for performing gender and sexuality. The article reviews these studies and their findings, identifying what they suggest about directions for future research, both in terms of developing methodology and refining approaches to sexuality and media consumption.</p

Cord Blood Acute Phase Reactants Predict Early Onset Neonatal Sepsis in Preterm Infants.

Early onset sepsis (EOS) is a major cause of morbidity and mortality in preterm infants, yet diagnosis remains inadequate resulting in missed cases or prolonged empiric antibiotics with adverse consequences. Evaluation of acute phase reactant (APR) biomarkers in umbilical cord blood at birth may improve EOS detection in preterm infants with intrauterine infection.In this nested case-control study, infants (29.7 weeks gestation, IQR: 27.7-32.2) were identified from a longitudinal cohort with archived cord blood and placental histopathology. Patients were categorized using culture, laboratory, clinical, and antibiotic treatment data into sepsis groups: confirmed sepsis (cEOS, n = 12); presumed sepsis (PS, n = 30); and no sepsis (controls, n = 30). Nine APRs were measured in duplicate from cord blood using commercially available multiplex immunoassays (Bio-Plex Pro™). In addition, placental histopathologic data were linked to biomarker results.cEOS organisms were Escherichia coli, Streptococcus agalactiae, Proteus mirabilis, Haemophilus influenzae and Listeria monocytogenes. C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (Hp), serum amyloid P and ferritin were significantly elevated in cEOS compared to controls (p<0.01). SAA, CRP, and Hp were elevated in cEOS but not in PS (p<0.01) and had AUCs of 99%, 96%, and 95% respectively in predicting cEOS. Regression analysis revealed robust associations of SAA, CRP, and Hp with EOS after adjustment for covariates. Procalcitonin, fibrinogen, α-2-macroglobulin and tissue plasminogen activator were not significantly different across groups. Placental acute inflammation was associated with APR elevation and was present in all cEOS, 9 PS, and 17 control infants.This study shows that certain APRs are elevated in cord blood of premature infants with EOS of intrauterine origin. SAA, CRP, and Hp at birth have potential diagnostic utility for risk stratification and identification of infants with EOS

Association Between the 7-Day Moving Average for Nutrition and Growth in Very Low Birth Weight Infants.

BACKGROUND: Very low birth weight (VLBW) infants remain at risk for postnatal growth restriction. Clinicians may have difficulty identifying growth patterns resulting from nutrition interventions, impeding prompt management changes intended to increase growth velocity. This study aimed to quantify the association between growth and nutrition intake through 7-day moving averages (SDMAs). METHODS: The first 6 weeks of daily nutrition intake and growth measurements were collected from VLBW infants admitted to a level 4 neonatal intensive care unit (2011-2014). The association between SDMA for energy and macronutrients and subsequent 7-day growth velocities for weight, length, and head circumference were determined using mixed effects linear regression. Analyses were adjusted for fluid intake, infant characteristics, and comorbid conditions. RESULTS: Detailed enteral and parenteral caloric provisions were ascertained for 115 infants (n = 4643 patient-days). Each 10-kcal/kg/d increase over 7 days was independently associated with increased weight (1.7 g/kg/d), length (0.4 mm/wk), and head circumference (0.9 mm/wk; P \u3c .001, for weight and head circumference; P = .041 for length). Each 1 g/kg/d macronutrient increase was also associated with increased weight (protein, P = .027; fat and carbohydrates, P \u3c .001), increased length (fat, P = .032), and increased head circumference (fat and carbohydrates, P \u3c .001). CONCLUSIONS: The SDMA identifies clinically meaningful associations among total energy, macronutrient dosing, and growth in VLBW infants. Whether SDMA is a clinically useful tool for providing clinicians with prompt feedback to improve growth warrants further attention

Metabolic Uncoupling Following Cardiopulmonary Bypass.

OBJECTIVE: The objective of this study was to characterize the natural history of metabolic uncoupling (type B hyperlactemia and hyperglycemia) following cardiopulmonary bypass (CPB), and to determine the impact of insulin therapy on time to lactate normalization in patients without low cardiac output. DESIGN: The design used was a retrospective cohort study. SETTING: The study was set in a pediatric cardiac intensive care unit in a tertiary-care urban children\u27s hospital. PATIENTS: All patients were aged ≤21 years admitted between 2007 and 2013 following cardiac surgery involving CPB with empiric intraoperative corticosteroids. ELIGIBILITY CRITERIA: simultaneous hyperlactemia (≥3.5 mEq/L) and hyperglycemia (≥200 mg/dL) within 48 hours after bypass. EXCLUSION CRITERIA: Exclusion criteria were evidence of low cardiac output state, diabetes or postoperative steroid administration. INTERVENTIONS: Characteristics were compared between those treated with insulin and those who were not (controls). OUTCOME MEASURES: Outcome measures used were time from admission to onset of hyperglycemia and hyperlactemia and time to resolution. Clinical outcomes included duration of mechanical ventilation, length of stay, unplanned readmission/reoperation, hypoglycemia and death. RESULTS: Of the 1345 patients receiving CPB, 132 (9.8%) met inclusion criteria. Seventy-eight (59%) were treated with insulin, leaving 54 controls. Patient characteristics, surgical complexity and time to onset of hyperglycemia and hyperlactemia were similar between groups. The insulin group had a shorter duration of hyperglycemia. There was no significant difference between groups in time to lactate normalization, ventilator days, length of stay, readmission and reoperation rates. Hypoglycemia (/dL) occurred in three patients. CONCLUSIONS: In children with metabolic uncoupling after CPB, insulin use did not shorten the time to lactate normalization or alter clinical outcomes. These findings suggest that type B hyperlactemia with hyperglycemia after CPB will resolve spontaneously and does not warrant specific treatment

Acute phase reactant levels in sepsis groups.

<p>Box and whisker plots displaying distribution of 9 APR biomarkers (SAA, CRP, Hp, ferritin, SAP, PCT, tissue plasminogen activator, fibrinogen, α-2-macroglobulin) in each sepsis category. *Indicates significant difference in APR values between cEOS and control groups. **Indicates significant difference in APR values between cEOS and PS groups.</p

Antibiotic duration and changes in FEV1 are not associated with time until next exacerbation in adult cystic fibrosis: a single center study

Abstract Background Pulmonary exacerbations (PEx) are a major driver of morbidity and mortality in cystic fibrosis and reducing their frequency by extending the time between them is an important therapeutic goal. Although treatment decisions for exacerbations are often made based on dynamic changes in lung function, it is not clear if these changes truly impact future exacerbation risk. We analyzed adults with chronic Pseudomonas aeruginosa infection to determine whether changes in FEV1 or duration of intravenous antibiotic therapy were associated with time to the next pulmonary exacerbation. Methods Medical records and Cystic Fibrosis Foundation Patient Registry data were examined retrospectively to assess whether various patient-specific demographic factors and exacerbation-specific characteristics were associated with time until next exacerbation using the Andersen-Gill model in order to control for previous exacerbation frequency history. Results We examined 59 patients with 221 CF pulmonary exacerbations over a 3-year study period. Mean age was 28.2 years and mean baseline FEV1 was 62% predicted. In our univariable model, fall in FEV1 at onset of exacerbation (median absolute −3% predicted change), recovery of FEV1 with treatment (median absolute +3% predicted change) and duration of IV antibiotics (median 16 days) were not associated with time to next exacerbation (median 93.5 days). Paradoxically each one-year increase in age was associated with a reduction in hazard of PEx by 3% (HR 0.97, P = 0.03, 95% CI 0.95–1.00). Conclusions FEV1 drop and recovery associated with onset and treatment of a CF pulmonary exacerbation or duration of intravenous antibiotics were not predictive of time until next exacerbation. Our finding that older age may be associated with decreased hazard of exacerbation is likely due to a healthy survivor effect and should be controlled for in clinical trials of pulmonary exacerbations

Case definition, demographics and placental histopathology.

<p>Case definition, demographics and placental histopathology.</p

Receiver operating characteristic curves.

<p>ROC curves for serum amyloid A, C-reactive protein, and haptoglobin. The above acute phase reactants had areas under the curve of >95% for prediction of EOS.</p