Experimental evidence of parametric decay processes in the variable specific impulse magnetoplasma rocket (VASIMR) helicon plasma source

Decay waves have been observed in the megahertz range in the helium plasma generated by the variable specific impulse magnetoplasma rocket magnetoplasma thruster. They are measured using one of the tips of a triple probe connected to a 50 Ω input of a spectrum analyzer via a dc block (a small capacitor). The maximum amplitude of all waves is in the center of the plasma and does not appear correlated to the radial electron density or temperature profiles. The waves seem to be generated close to the helicon antenna that was 91 cm “upstream” from the measuring Langmuir probe. A possible explanation is parametric decay of the large amplitude helicon wave that also generates the plasma.This project was proudly supported by the International Science Linkages programme established under the Australian Government’s innovation statement Backing Australia’s Ability

Validating a Plasma Momentum Flux Sensor to an Inverted Pendulum Thrust Stand

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76451/1/AIAA-35706-298.pd

Robotic Lunar Landers for Science and Exploration

NASA Marshall Space Flight Center (MSFC) and The Johns Hopkins University Applied Physics Laboratory (APL) have been conducting mission studies and performing risk reduction activities for NASA s robotic lunar lander flight projects. This paper describes some of the lunar lander concepts derived from these studies conducted by the MSFC/APL Robotic Lunar Lander Development Project team. In addition, the results to date of the lunar lander development risk reduction efforts including high pressure propulsion system testing, structure and mechanism development and testing, long cycle time battery testing and combined GN&C and avionics testing will be addressed. The most visible elements of the risk reduction program are two autonomous lander flight test vehicles: a compressed air system with limited flight durations and a second version using hydrogen peroxide propellant to achieve significantly longer flight times and the ability to more fully exercise flight sensors and algorithms

Heart ventricular activation in VAT difference maps from children with chronic kidney disease

Children with chronic kidney disease (CKD) are affected by cardiovascular complications, including disturbances in the intraventricular conduction system. Body surface potential mapping (BSPM) is a non-invasive method of assessing the cardioelectrical field. Our aim was to investigate conduction disturbances in young CKD patients using ventricular activation time (VAT) maps. Our study comprised 22 CKD children (mean age: 13.1 ± 2.5 years) treated conservatively and 29 control patients. For each child 12-lead electrocardiogram (ECG) readings were taken, and blood pressure and serum concentrations of iPTH, Pi, t-Ca, creatinine, Fe+3, ferritin, and Hb, as well as eGFR were measured. All children underwent registration in the 87-lead BSPM system, and group-mean VAT maps and a difference map, which presents statistically significant differences between the groups, were created. The VAT map distribution in CKD patients revealed abnormalities specific to left anterior fascicle block. The difference map displays the areas of intergroup VAT changes, which are of discriminative value in detecting intraventricular conduction disturbances. Intraventricular conduction impairments in the left bundle branch may occur in children with CKD. BSPM enables conduction disturbances in CKD children to be detected earlier than using 12-lead ECG. The difference map derived from the group-mean isochrone maps precisely localizes the sites of disturbed conduction in the heart intraventricular conduction system

Rotavirus symptomatic infection among unvaccinated and vaccinated children in Valencia, Spain

BACKGROUND: Human group A rotavirus is the leading cause of severe acute gastroenteritis in young children worldwide. Immunization programs have reduced the disease burden in many countries. Vaccination coverage in the Autonomous Region of Valencia, Spain, is around 40%, as the rotavirus vaccine is not funded by the National Health System. Despite this low-medium vaccine coverage, rotavirus vaccination has substantially reduced hospitalizations due to rotavirus infection and hospital-related costs. However, there are very few studies evaluating symptomatic rotavirus infections not requiring hospitalization in vaccinated children. The objective of this study was to investigate symptomatic rotavirus infections among vaccinated children in the health area served by the Hospital Clínico Universitario of Valencia, Spain, from 2013 to 2015. METHODS: A total of 133 children younger than 5 years of age with rotavirus infection were studied. Demographic and epidemiological data were collected and informed consent from their caretakers obtained. Rotavirus infection was detected by immunological methods and G/P rotavirus genotypes were determined by RT-PCR, following standard procedures from the EuroRotaNet network. RESULTS: Forty infants (30.1%; 95% CI: 22.3-37.9) out of 133 were diagnosed with symptomatic rotavirus infection despite having been previously vaccinated, either with RotaTeq (85%) or with Rotarix (15%). Children fully vaccinated against rotavirus (24.8%), partially vaccinated (5.3%) and unvaccinated (69.9%) were found. The infecting genotypes showed high G-type diversity, although no significant differences were found between the G/P genotypes infecting vaccinated and unvaccinated children during the same time period. G9P[8], G12P[8] and G1P[8] were the most prevalent genotypes. Severity of gastroenteritis symptoms required 28 (66.6%) vaccinated and 67 (73.6%) unvaccinated children to be attended at the Emergency Room. CONCLUSION: Rotavirus vaccine efficacy in reducing the incidence of severe rotavirus infection has been well documented, but symptomatic rotavirus infection can sometimes occur in vaccinees

Long-term outcome of chronic dialysis in children

As the prevalence of children on renal replacement therapy (RRT) increases world wide and such therapy comprises at least 2% of any national dialysis or transplant programme, it is essential that paediatric nephrologists are able to advise families on the possible outcome for their child on dialysis. Most children start dialysis with the expectation that successful renal transplantation is an achievable goal and will provide the best survival and quality of life. However, some will require long-term dialysis or may return intermittently to dialysis during the course of their chronic kidney disease (CKD). This article reviews the available outcome data for children on chronic dialysis as well as extrapolating data from the larger adult dialysis experience to inform our paediatric practice. The multiple factors that may influence outcome, and, particularly, those that can potentially be modified, are discussed

CKD-MBD after kidney transplantation

Successful kidney transplantation corrects many of the metabolic abnormalities associated with chronic kidney disease (CKD); however, skeletal and cardiovascular morbidity remain prevalent in pediatric kidney transplant recipients and current recommendations from the Kidney Disease Improving Global Outcomes (KDIGO) working group suggest that bone disease—including turnover, mineralization, volume, linear growth, and strength—as well as cardiovascular disease be evaluated in all patients with CKD. Although few studies have examined bone histology after renal transplantation, current data suggest that bone turnover and mineralization are altered in the majority of patients and that biochemical parameters are poor predictors of bone histology in this population. Dual energy X-ray absorptiometry (DXA) scanning, although widely performed, has significant limitations in the pediatric transplant population and values have not been shown to correlate with fracture risk; thus, DXA is not recommended as a tool for the assessment of bone density. Newer imaging techniques, including computed tomography (quantitative CT (QCT), peripheral QCT (pQCT), high resolution pQCT (HR-pQCT) and magnetic resonance imaging (MRI)), which provide volumetric assessments of bone density and are able to discriminate bone microarchitecture, show promise in the assessment of bone strength; however, future studies are needed to define the value of these techniques in the diagnosis and treatment of renal osteodystrophy in pediatric renal transplant recipients