The Magnetic Sun: Reversals and Long-Term Variations

A didactic introduction to current thinking on some aspects of the solar dynamo is given for geophysicists and planetary scientists.Comment: 17 pages, 9 figures; Space Science Rev., in pres

Generation of electron high energy beams with a ring-like structure by a dual stage laser wakefield accelerator

The laser wake-field accelerator (LWFA) traditionally produces high brightness, quasi-monoenergetic electron beams with Gaussian-like spatial and angular distributions. In the present work we investigate the generation of ultra-relativistic beams with ring-like structures in the blowout regime of the LWFA using a dual stage accelerator. A density down-ramp triggers injection after the first stage and is used to produce ring-like electron spectra in the 300 – 600 MeV energy range. These well defined, annular beams are observed simultaneously with the on-axis, high energy electron beams, with a divergence of a few milliradians. The rings have quasi-monoenergetic energy spectra with an RMS spread estimated to be less than 5%. Particle-in-cell simulations confirm that off-axis injection provides the electrons with the initial transverse momentum necessary to undertake distinct betatron oscillations within the plasma bubble during their acceleration process

Can Tall Guinea-Race Sorghum Hybrids Deliver Yield Advantage to Smallholder Farmers in West and Central Africa?

Many farmers in West and Central Africa (WCA) prefer tall (>3 m) grain sorghum [Sorghum bicolor (L.) Moench] for various reasons. This study seeks to determine (i) what yield superiority newly bred, tall, photoperiod-sensitive guinea-race sorghum hybrids can provide relative to an adapted landrace variety across a wide range of productivity conditions, and (ii) the risk of these hybrids failing to provide yield superiority for individual farmers. Seven hybrids, one local check, and eight pure-line progenies were evaluated in 37 farmer-managed, on-farm yield trials across three Malian zones and 3 yr. Environments were classified into four productivity groups (low [0.78–1.10 Mg ha−1], mid-low [1.10–1.50 Mg ha−1], mid-high [1.50–2.00 Mg ha−1] and high [2.00–2.65 Mg ha−1]) based on their trial mean grain yield. Mean yields of the seven tall hybrids were 3 to 17% (ranging from 0.06 to 0.28 Mg ha−1) higher than that of the local check across all environments and were highest (14–47%) averaged across the seven trials with the lowest mean yields. The individual overall highest-yielding hybrid showed superiorities over the local check in the low, mid-low, mid-high, and high productivity levels of 0.43 (47%), 0.14 (10%), 0.47 (27%), and 0.34 (14%) Mg ha−1, respectively. The tall hybrids rarely had yields significantly inferior to the local check. Farmers’ preference for, and the possible benefits of, taller plant types may lead farmers to grow tall hybrids, particularly under the typical low-productivity production conditions of WCA

Vitamin B12 deficiency following restorative proctocolectomy

Objective Restorative proctocolectomy (RP) involves terminal ileal resection and formation of a small bowel reservoir that predisposes to bacterial overgrowth. It was anticipated that these patients would be at risk of vitamin B12 deficiency. Method Vitamin B12 levels were measured sequentially in 171 patients who underwent RP. Prospective results were obtained from all 20 patients undergoing pouch formation after the commencement of the study. Further results were obtained retrospectively from case notes and computerized laboratory records of the 151 patients who underwent RP prior to the commencement of the study and these were correlated with the results of follow‐up samples taken prospectively from the same patients after the commencement of the study. The median age of the patients was 40 years (range: 13–67) and the median duration of follow up was 5.4 years (range: 1–12). Patients with an abnormally low serum B12 level underwent both a Schilling and a hydrogen breath test. Eight of these patients were then treated with oral vitamin B12. Results Abnormally low serum B12 levels were found in 25% of patients. Forty per cent of our patient group had three or more sequential B12 measurements and of these, 66% showed steadily declining B12 levels. Ninety‐four per cent of patients with low B12 had a normal Schilling test and were negative for bacterial overgrowth. Conclusion Subnormal vitamin B12 levels develop in almost one‐quarter of patients after pouch surgery. The exact mechanism for B12 deficiency in these patients is uncertain. In the majority of patients undergoing RP, vitamin B12 levels fall on sequential measurement. Serum B12 levels should be measured during follow up and pouch patients with subnormal B12 levels, should see them successfully restored to a normal value after treatment with oral B12 replacement therapy