Introduction:There is shortage of active blood donors to meet the increased demand. Precisely aimed promotion and information, targeted motivation and selection of non-remunerated healthy volunteer donors are needed for an adequate and safe blood and blood products supply. Objectives:The objectives of this study are to assess the knowledge, attitude and practice of voluntary blood donation among physician, to identify and recruit potential voluntary blood donors amongst them and to determine the association between blood donation and gender, duration of practice and sub specialty of the physicians.

Background and aims: Fluid requirements of children vary as a function of gender and age. To our knowledge, there is very little literature on the hydration status of Italian children. We assessed morning hydration status in a large sample of 515 Italian school children aged 9 to 11 years. Methods: Recruited children completed a questionnaire on fluid and food intake at breakfast and collected a urine sample the very same day after breakfast. Breakfast food and fluid nutritional composition was analysed and urine osmolality was measured using a cryoscopic osmometer. Results: More than two thirds of the children had urine osmolality above 800 mOsmol/kg while 35.0% had urine osmolality over 1000 mOsmol/kg. This was more frequent in boys than in girls (71.9% versus 62.5%; p=0.02). Total water intake (water coming from both food and fluid) as well as total fluid intake at breakfast were significantly and inversely correlated with urine osmolality. Conclusions: Almost two thirds of the children in this large cohort had evidence of a hydration deficit when they went to school in the morning, despite breakfast intake. Children's fluid intake at breakfast does not suffice to maintain an adequate hydration status for the whole morning.

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The flight simulator is one kind of servo system with uncertainties and disturbances. To obtain high performance and good robustness for the flight simulator, we present a robust Backstepping controller based on a Disturbance Observer. Firstly, the design procedure of the robust Backstepping controller is described and correlative problems are proposed. Secondly, the principle and the design process of Disturbance Observer are analyzed and expatiated respectively. Finally, simulation results on the flight simulator show that the Disturbance Observer can compensate external disturbances including system input and output disturbance and the system performance can be improved. Therefore both robustness and high performance of the flight simulator are achieved. It is an applied technology for the control of servo system, such as the flight simulator.

Oceanography and Marine Research J o u rn al of Oc e a n o g ra p y h an d M a ri ne Res e a r c h