Recovery of spinning satellites

The behavior of a space tug and a spinning satellite in a coupled configuration was simulated and analyzed. A docking concept was developed to investigate the requirements pertaining to the design of a docking interface. Sensing techniques and control requirements for the chase vehicle were studied to assess the feasibility of an automatic docking. The effects of nutation dampers and liquid propellant slosh motion upon the docking transient were investigated

Impacts of climate change on dissolved oxygen concentration relevant to the coastal and marine environment around the UK

The decline in dissolved oxygen and onset of oxygen deficiency and hypoxia are naturally occurring phenomenon in aquatic environments, typically occurring on seasonal timescales. Over decadal timescales, there has been a measurable decline in dissolved oxygen concentrations in the global ocean due to warming caused by anthropogenic activity. Approximately 15% of the global decline in oxygen has been attributed to reduced solubility in response to ocean warming, with the remaining 85% due to intensified stratification. The relative contribution of these factors in coastal and shelf-sea waters is currently unknown. In UK waters, sustained observations in the North Sea reveal the recent onset of oxygen deficiency in late summer, partially due to ocean warming. Models designed to represent coastal and shelf sea processes suggest there are large parts of the Celtic Sea, English Channel and Irish Sea that are prone to oxygen deficiency, but data is too sparse in time and space to support these findings. In addition, the ability of models to accurately represent oxygen dynamics is still under debate due to correct representation of physical and biological processes within models. Physical processes play a key role in the development of oxygen deficient regions and thus understanding how oxygen concentrations will respond to climate change requires a coupled physical and biogeochemical approach

Intercomparison of retrospective radon detectors.

We performed both a laboratory and a field intercomparison of two novel glass-based retrospective radon detectors previously used in major radon case-control studies performed in Missouri and Iowa. The new detectors estimate retrospective residential radon exposure from the accumulation of a long-lived radon decay product, (210)Pb, in glass. The detectors use track registration material in direct contact with glass surfaces to measure the alpha-emission of a (210)Pb-decay product, (210)Po. The detector's track density generation rate (tracks per square centimeter per hour) is proportional to the surface alpha-activity. In the absence of other strong sources of alpha-emission in the glass, the implanted surface alpha-activity should be proportional to the accumulated (210)Po, and hence to the cumulative radon gas exposure. The goals of the intercomparison were to a) perform collocated measurements using two different glass-based retrospective radon detectors in a controlled laboratory environment to compare their relative response to implanted polonium in the absence of environmental variation, b) perform collocated measurements using two different retrospective radon progeny detectors in a variety of residential settings to compare their detection of glass-implanted polonium activities, and c) examine the correlation between track density rates and contemporary radon gas concentrations. The laboratory results suggested that the materials and methods used by the studies produced similar track densities in detectors exposed to the same implanted (210)Po activity. The field phase of the intercomparison found excellent agreement between the track density rates for the two types of retrospective detectors. The correlation between the track density rates and direct contemporary radon concentration measurements was relatively high, considering that no adjustments were performed to account for either the residential depositional environment or glass surface type. Preliminary comparisons of the models used to translate track rate densities to average long-term radon concentrations differ between the two studies. Further calibration of the retrospective detectors' models for interpretation of track rate density may allow the pooling of studies that use glass-based retrospective radon detectors to determine historic residential radon exposures

Relationship between blood lead concentration and nutritional status among Malay primary school children in Kuala Lumpur, Malaysia.

A cross-sectional study was conducted to identify the relationship between blood lead concentration and nutritional status among primary school children in Kuala Lumpur. A total of 225 Malay students, 113 male and 112 female, aged 6.3 to 9.8 were selected through a stratified random sampling method. The random blood samples were collected and blood lead concentration was measured by a Graphite Furnace Atomic Absorption Spectrophotometer. The nutrient intake was determined by the 24-hour Dietary Recall method and Food Frequency Questionnaire. An anthropometric assessment was reported according to growth indices (z-scores of weight-for-age, height-for-age, and weight-for-height). The mean blood lead concentration was low (3.4 ± 1.91 ug/dL) and was significantly different between gender. Only 14.7% of the respondents fulfilled the daily energy requirement. The protein and iron intakes were adequate for a majority of the children. However, 34.7% of the total children showed inadequate intake of calcium. The energy, protein, fat and carbohydrate intakes were significantly different by gender, that is, males had better intake than females. Majority of respondents had normal mean z-score of growth indices. Ten percent of the respondents were underweight, 2.8% wasted and 5.4% stunted. Multiple linear regression showed inverse significant relationships between blood lead concentration with children's age (β= -0.647, p<0.001) and per capita income (β=-0.001, p=0.018). There were inverse significant relationships between blood lead concentration with children's age (β=-0.877, p=0.001) and calcium intake (β= -0.011,p=0.014) and positive significant relationship with weight-for-height (β=0.326, p=0.041) among those with inadequate calcium intake. Among children with inadequate energy intake, children's age (β= -0.621, p< 0.001), per capita income (β= -0.001,p=0.025) and protein intake (β= -0.019, p=0.027) were inversely and significantly related with blood lead concentration. In conclusion, nutritional status might affect the children's absorption of lead and further investigation is required for confirmation

GO-SHIP Repeat Hydrography Nutrient Manual: The Precise and Accurate Determination of Dissolved Inorganic Nutrients in Seawater, Using Continuous Flow Analysis Methods

The GO-SHIP nutrient manual covers all aspects of nutrient analysis from basic sample collection and storage, specifically for Continuous Flow analysis using an Auto-Analyzer, and describes some specific nutrient methods for Nitrate, Nitrite, Silicate, Phosphate and Ammonium that are in use by many laboratories carrying out at-sea analysis and repeat hydrography sections across the world. The focus is on segmented flow analyzers not flow injection analyzers. It also covers laboratory best practices including quality control and quality assurance (QC/QA) procedures to obtain the best results, and suggests protocols for the use of reference materials (RM) and certified reference materials (CRMs)

Associations of the mechanical, anthropometric and gait contributors to the knee adduction moment during paediatric gait

The knee adduction moment (KAM) during gait has been proposed as an indirect measure of dynamic knee joint loading and has been reported to be higher in obese children [1, 2]. The KAM is primarily calculated from the resultant ground reaction force (GRF) and the lever arm length, both of which can be manipulated through weight-loss or medical interventions [1]. However, there is little data on the relationships between the mechanical, anthropometric and gait contributors to the KAM during paediatric gait. The objectives of the study were to examine the associations with the first (1st) and second (2nd) peak KAM (pKAM) and: (1) centre of pressure (CoP), KAM lever arm length, vertical and mediolateral ground reaction forces (GRF) and, (2) fat mass, height, step width, foot rotation, knee rotation and walking velocity