Technology alternatives for the SPS

Emerging technologies may offer advantages over those selected for the reference design adopted for the SPS. While it is not possible to list all the technological innovations that may affect the SPS, it is feasible to develop a systematic methodology for assessing technical alternatives. This may be of value in evaluating proposed technologies and identifying high priority areas for research. Such a methodology includes involves (1) variation of guidelines; (2) analysis of system functions; (3) analysis of system sensitivity; (4) analysis of technology status and risk; and (5) external costs, problem areas, and criticisms of the SPS concept. The methodology is a first step towards the creation of a formal decision analytic framework which can support design choices and program decisions as development proceeds

Laser absorption phenomena in flowing gas devices

A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster

Mathematical models of avascular cancer

This review will outline a number of illustrative mathematical models describing the growth of avascular tumours. The aim of the review is to provide a relatively comprehensive list of existing models in this area and discuss several representative models in greater detail. In the latter part of the review, some possible future avenues of mathematical modelling of avascular tumour development are outlined together with a list of key questions

Mathematical models of avascular cancer

This review will outline a number of illustrative mathematical models describing the growth of avascular tumours. The aim of the review is to provide a relatively comprehensive list of existing models in this area and discuss several representative models in greater detail. In the latter part of the review, some possible future avenues of mathematical modelling of avascular tumour development are outlined together with a list of key questions

Podiatry services for patients with arthritis: an unmet need

Foot problems are extremely common in patients with rheumatoid arthritis (RA). There is ample evidence that foot pain, either alone or as a comorbidity, contributes significantly to disability. Despite the high prevalence of foot disease in RA, this problem is often trivialised or underappreciated. The inequity in foot health provision for patients with rheumatic disorders in New Zealand has recently been highlighted. Expertise in dealing with foot problems is often limited among healthcare professionals, and it has been argued that better integration of podiatric services into rheumatology services would be beneficial. The aim of this paper is to highlight the major issues related to foot care for patients with arthritis and provide key recommendations that should implemented to improve access to podiatric services in New Zealand

Analytical and experimental investigations of low level acceleration measurement techniques

Construction techniques for accelerometer with low level threshold sensitivit

Studies of orbital Eoetvoes experiments

A direct force-balance technique was analyzed for carrying out the Eoetvoes experiment in space, which is intended to give sufficient sensitivity to allow investigation of the gravitational interactions of energy stored in the weak interaction. The heart of experiment is an exceedingly sensitive dual accelerometer, containing two proof masses constructed of the materials whose Eoetvoes ratio is to be compared. For use in development of the accelerometer, a magnetic microbalance is proposed in which the weight of the proof mass is supported by magnetic forces which vary very slowly with the proof mass position. It is shown that at least two different mechanizations of the magnetic suspension may be feasible

Observations of cosmic ray induced phosphenes

Phosphene observations by astronauts on flights near and far from earth atmosphere are discussed. It was concluded that phosphenes could be observed by the naked eye. Further investigation is proposed to determine realistic human tolerance levels for extended missions and to evaluate the need to provide special spacecraft shielding

Variable renewal rate and growth properties of cell populations in colon crypts

A nonlinear mathematical model is used to investigate the time evolution of the cell populations in colon crypts (stem, semidifferentiated and fully differentiated cells). To mimic pathological alteration of the biochemical pathways leading to abnormal proliferative activity of the population of semidifferentiated cells their renewal rate is assumed to be dependent on the population size. Then, the effects of such perturbation on the population dynamics are investigated theoretically. Using both theoretical methods and numerical simulations it is shown that the increase in the renewal rate of semidifferentiated cells strongly impacts the dynamical behavior of the cell populations