Ion thrusters for electric propulsion: Scientific issues developing a niche technology into a game changer.

The transition from old space to new space along with increasing commercialization has a major impact on space flight, in general, and on electric propulsion (EP) by ion thrusters, in particular. Ion thrusters are nowadays used as primary propulsion systems in space. This article describes how these changes related to new space affect various aspects that are important for the development of EP systems. Starting with a historical overview of the development of space flight and of the technology of EP systems, a number of important missions with EP and the underlying technologies are presented. The focus of our discussion is the technology of the radio frequency ion thruster as a prominent member of the gridded ion engine family. Based on this discussion, we give an overview of important research topics such as the search for alternative propellants, the development of reliable neutralizer concepts based on novel insert materials, as well as promising neutralizer-free propulsion concepts. In addition, aspects of thruster modeling and requirements for test facilities are discussed. Furthermore, we address aspects of space electronics with regard to the development of highly efficient electronic components as well as aspects of electromagnetic compatibility and radiation hardness. This article concludes with a presentation of the interaction of EP systems with the spacecraft.

[Multidimensional pain assessment in patients with dementia]. / Mehrdimensionale Schmerzmessung bei Demenzpatienten.

BACKGROUND: It is well known that patients with dementia complain less about pain and receive fewer analgesics than other patients. The question arises of whether disorders associated with dementia change the processing of pain. METHODS: A total of 20 patients with dementia and 40 patients with mild cognitive impairment (MCI) as well as 40 healthy control subjects were investigated for their subjective (category scale), facial (FACS) and motor (R-III reflex) pain responses to mechanical and electrical stimuli. RESULTS: Patients with dementia did not rate the intensity of the stimuli differently; however, they were less frequently capable of providing ratings. At equal levels of stimulus intensity, demented patients showed stronger facial responses. The R-III reflex thresholds were lowered in demented patients. MCI patients appeared only slightly changed. CONCLUSIONS: Our findings suggest that the processing of acute noxious stimuli is intensified in patients with dementia. Against the background of a reduced prescription of analgesics, an under-treatment of pain in patients with dementia might be the consequence.

Restrained eating is associated with low leptin levels in underweight females.

Psychometrically defined restrained eaters consume fewer calories, take fewer meals, show higher preference for low calorie foods, have lower energy expenditure and a higher rate of ovarial dysfunction than unrestrained eaters. We hypothesized that restrained eaters as assessed with the factor cognitive restraint of the Three-Factor Eating Questionnaire have low leptin levels; therefore, we measured serum leptin levels in 136 underweight students and 49 overweight students, who had filled out the Three-Factor Eating Questionnaire. Body mass indexes, fat mass and percent body fat were determined. Spearman correlations revealed that log10 leptin levels of only the 67 underweight females were negatively correlated with cognitive restraint scores (r = -0.5; nominal P-value < 0.001). The restraint score explained 22% of the total variance of leptin levels in underweight females; in combination with percent body fat, 52% of the variance was accounted for. To our knowledge this is the first study to identify a relationship between a score on a psychometric scale and leptin levels. Restrained eating has a biological correlate in underweight females.