Invited article: development of high-field superconducting Ioffe magnetic traps

We describe the design, construction, and performance of three generations of superconducting Ioffe magnetic traps. The first two are low current traps, built from four racetrack shaped quadrupole coils and two solenoid assemblies. Coils are wet wound with multifilament NbTi superconducting wires embedded in epoxy matrices. The magnet bore diameters are 51 and 105 mm with identical trap depths of 1.0 T at their operating currents and at 4.2 K. A third trap uses a high current accelerator-type quadrupole magnet and two low current solenoids. This trap has a bore diameter of 140 mm and tested trap depth of 2.8 T. Both low current traps show signs of excessive training. The high current hybrid trap, on the other hand, exhibits good training behavior and is amenable to quench protection.     

Measurement of the Neutron Lifetime Using a Gravitational Trap and a Low-Temperature Fomblin Coating

We present a new value for the neutron lifetime of 878.5 ± 0.7_stat. ± 0.3_syst. This result differs from the world average value by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a β-asymmetry in neutron decay, A₀, of −0.1189(7) is in a good agreement with the Standard Model.     

North–South divide: contrasting impacts of climate change on crop yields in Scotland and England

Effects of climate change on productivity of agricultural crops in relation to diseases that attack them are difficult to predict because they are complex and nonlinear. To investigate these crop–disease–climate interactions, UKCIP02 scenarios predicting UK temperature and rainfall under high- and low-CO₂ emission scenarios for the 2020s and 2050s were combined with a crop-simulation model predicting yield of fungicide-treated winter oilseed rape and with a weather-based regression model predicting severity of phoma stem canker epidemics. The combination of climate scenarios and crop model predicted that climate change will increase yield of fungicide-treated oilseed rape crops in Scotland by up to 0.5 t ha⁻¹ (15%). In contrast, in southern England the combination of climate scenarios, crop, disease and yield loss models predicted that climate change will increase yield losses from phoma stem canker epidemics to up to 50 per cent (1.5 t ha⁻¹) and greatly decrease yield of untreated winter oilseed rape. The size of losses is predicted to be greater for winter oilseed rape cultivars that are susceptible than for those that are resistant to the phoma stem canker pathogen Leptosphaeria maculans. Such predictions illustrate the unexpected, contrasting impacts of aspects of climate change on crop–disease interactions in agricultural systems in different regions.     

Discharge Measurement Using Portable Dilution Gauging Flowmeters

This paper suggests that the relative salt (sodium chloride) dilution method should be more widely used for the routine measurement of stream discharge, and has been written to increase awareness of the technique among flow-gauging practitioners. Recent improvements in instrumentation have increased accuracy and simplified practical application, making the method better suited (in many circumstances) than the more widely used alternatives. The paper (a) reports on a field study to evaluate the performance of a portable dilution-gauging flowmeter, and (b) considers the environmental issues which are associated with the method. The review reveals that the use of salt (in the quantities typically required) is unlikely to have any significant ecological impact, and argues that environmental concerns are founded upon little scientific basis.     

Short-term memory impairment and arithmetical ability

We document the dissociation of preserved calculation skills in a patient with impaired auditory short-term memory. The patient (MRF) had a memory span of three digits. Furthermore, he showed rapid decrement in performance of single digits and letters with both auditory and visual presentation in the Brown-Peterson forgetting task. Analysis of his calculation skills revealed a normal ability to solve auditorily presented multidigit addition and subtraction problems such as 173 + 68 and to execute the Paced Auditory Serial Addition Task (Sampson, 1956, 1958; Gronwall, 1977). In addition, his performance on other tests, including arithmetic manipulation of natural numbers, decimals and fractions, approximation, magnitude, ratio, and percentage, appeared to be normal (Hitch, 1978b). It is argued that these findings require a revision of Baddeley and Hitch's (1974) concept of the function of working memory.     

Patterns of chloroform-induced regenerative cell proliferation in BDF1 mice correlate with organ specificity and dose-response of tumor formation

Drawing arm movements in four different directions: a) upward vertical (0 degree), b) upward oblique (45 degrees), c) downward vertical (180 degrees) and d) downward oblique (135 degrees), and at two different speeds, normal and fast, were executed by eight subjects. Movements of the arm were recorded using an optoelectronic (2 TV, 100 Hz) system which allowed the computer reconstruction of joint motion. Analyses focused upon pen kinematics in the frontal plane. Velocity profiles were unimodal for all conditions. The ratio of acceleration time to total movement time changed significantly as a function of the direction and the speed of the movement. Movement time and was not affected by movement direction and consequently changes in gravitational torques, for both speeds tested. Results from this study provide indirect evidence that the CNS executes movements by taking advantage of gravitational force.