Numerical Simulations of Pinhole and Single Mode Fibre Spatial Filters for Optical Interferometers

We use a numerical simulation to investigate the effectiveness of pinhole spatial filters at optical/IR interferometers and to compare them with single-mode optical fibre spatial filters and interferometers without spatial filters. We show that fringe visibility measurements in interferometers containing spatial filters are much less affected by changing seeing conditions than equivalent measurements without spatial filters. This reduces visibility calibration uncertainties, and hence can reduce the need for frequent observations of separate astronomical sources for calibration of visibility measurements. We also show that spatial filters can increase the signal-to-noise ratios of visibility measurements and that pinhole filters give signal-to-noise ratios within 17% of values obtained with single-mode fibres for aperture diameters up to 3r_0. Given the simplicity of the use of pinhole filters we suggest that it represents a competitive, if not optimal, technique for spatial filtering in many current and next generation interferometers.Comment: 7 pages, 7 postscript figures. Accepted by MNRA

Iodine in the nutrition of sheep. Final report

1. Two groups of 10 merino ewes were fed the same adequate basal ration with the exception that one group received an addition of 0.05 gms. each daily of potassium iodide. 2. A slight depression of weight and greater irregularity in regard to the reproduction was shown by the group that received the iodine supplement. The detrimental effects, however, were not as marked as recorded in previous work where other deficiencies, especially vitamin A, undoubtedly exercised an aggravating influence on reproductive abnormalities. 3. The indiscriminate use of iodine supplements for sheep is not recommended.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Studies in mineral metabolism. XXXIII. Iodine in the nutrition of sheep. Second report

1. Data are presented on the effect of KI in the feed of 40 merino ewes for a period of 30 months. 2. The quantities of KI given per sheep daily were 0.002 grm., 0.02 grm., 0.06 grm. in three groups respectively, while one group received no KI and acted as controls. 3. Observations were made on the food consumption, weight increase, wool production, reproduction and health of the animals for the full period of the experiment. Further, observations were made on the oestrus cycle of the ewes and no significant group differences were observed. 4. The animals were fed in individual feeding boxes except the hay, which was given ad lib. 5. It is concluded that neither the small dose nor the bigger quantities of KI fed had any visible effect on the weights, wool production and reproduction of the animals. 6. It is also pointed out that the ill effects ascribed to iodide feeding in the earlier work were apparently aggravated by another deficiency, the possibility of the existence of which was not considered in the earlier work, viz. vitamin A. 7. It is concluded that the addition of KI to sheep licks is unwarranted, may even produce visibly detrimental effects under conditions of drought, when a vitamin A shortage may exist, and is to be discouraged in practical farming unless there is reason for believing that an iodine deficiency exists. 8. Further work on the effects of iodine feeding under practical conditions, as for instance during severe droughts when apparently detrimental effects may be experienced, is being undertaken. The writers wish to acknowledge gratefully the assistance of Mr. A. P. Malan, Statistician, in dealing with the results given in the lambing charts.The articles have been scanned in colour with a HP Scanjet 5590;300dpi. adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Experimental osteodystrophic diseases in goats

(1) Starvation proved to be an important factor in the development of bone atrophy in the case of two kids which received a ration low in calcium and high in phosphorus, where the CaO:P₂O₅ ratio was wide. (2) Clinical symptoms of rickets were observed only in a case where the phosphorus intake was low and that of calcium high, with a wide ratio. (3) When the calcium and phosphorus intakes were both low, their ratio being normal, the histological examination of the bone showed the presence of rickets. (4) The inhibition of normal growth, due to semi-starvation, resulted in the eventual development of bone atrophy and not osteofibrosis. Even rickets, which is more easily produced than osteofibrosis, in time gives way to atrophy in the presence of cessation of bone growth.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

A field evaluation of the BGI and cowl type gravimetric samplers

After initial studies by the CSIR indicating that a discrepancy exists in the dust concentration results between gravimetric dust samplers, alternative instruments or methods were sought. In the study that followed; it was recommended by the HSL in the UK that a cowl arrangement, together with a sampling rate equivalent to the CEN / ISO standard, be used to minimize over sampling. As such CEN/ISO recommended sampling rate of 2.2 l/min was used for the first time in South African mines. A BGIstainless steel cyclone sampler and a Higgins Dewell type sampler with a cowl arrangement were used in the study. Implementation of the recommended changes to samplers and the flow rate will interrupt the continuity of monitoring data built up over the years, but they will raise South African dust measurements to international standards. Although extensive work has been carried out on the use of cyclones, most of the previous studies were carried out in the laboratory, which have an advantage over the extremely difficult conditions in underground coal mines. This paper describes the field results from the two gravimetric samplers tested underground.The authors would like to acknowledge the financial support of CSIR-Miningtek and SIMRAC.CSIR-Miningtek and SIMRAC.http://www.mvssa.co.zaam2017Mining Engineerin

Studies in mineral metabolism XXXV. The role of iodine in the nutrition of sheep

When the daily ration of Merino ewes contained 0.05 gm. KI for a period of about twelve months no effects were observed in bodyweight and food consumption. Reproduction was, however, abnormal in all the groups receiving the KI supplement, the effects of which were more pronouncedly deleterious in sheep on a carotene low diet than when 200 grm. greenfeed were supplied daily. The response to increased protein feeding in the form of bloodmeal was marked by the detrimental effect of KI on reproduction. As all the rations can easily be improved both in quality and palatability it cannot be inferred that the quantity of KI given will affect reproduction in sheep adversely under ideal feeding conditions. The conclusion is justified, however, that when greenfeed is absent or inadequate as frequently happens in practice good quality protein is not available and the incorporation of KI in sheep licks is distinctly dangerous and may even cause losses due to abnormal reproduction.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Study protocol: a randomised controlled trial on the clinical effects of levothyroxine treatment for subclinical hypothyroidism in people aged 80 years and over

Background: Subclinical hypothyroidism is common in older people and its contribution to health and disease needs to be elucidated further. Observational and clinical trial data on the clinical effects of subclinical hypothyroidism in persons aged 80 years and over is inconclusive, with some studies suggesting harm and some suggesting benefits, translating into equipoise whether levothyroxine therapy provides clinical benefits. This manuscript describes the study protocol for the Institute for Evidence-Based Medicine in Old Age (IEMO) 80-plus thyroid trial to generate the necessary evidence base. Methods: The IEMO 80-plus thyroid trial was explicitly designed as an ancillary experiment to the Thyroid hormone Replacement for Untreated older adults with Subclinical hypothyroidism randomised placebo controlled Trial (TRUST) with a near identical protocol and shared research infrastructure. Outcomes will be presented separately for the IEMO and TRUST 80-plus groups, as well as a pre-planned combined analysis of the 145 participants included in the IEMO trial and the 146 participants from the TRUST thyroid trial aged 80 years and over. The IEMO 80-plus thyroid trial is a multi-centre randomised double-blind placebo-controlled parallel group trial of levothyroxine treatment in community-dwelling participants aged 80 years and over with persistent subclinical hypothyroidism (TSH ≥4.6 and ≤ 19.9 mU/L and fT4 within laboratory reference ranges). Participants are randomised to levothyroxine 25 or 50 micrograms daily or matching placebo with dose titrations according to TSH levels, for a minimum follow-up of one and a maximum of three years. Primary study endpoints: hypothyroid physical symptoms and tiredness on the thyroid-related quality of life patient-reported outcome (ThyPRO) at one year. Secondary endpoints: generic quality of life, executive cognitive function, handgrip strength, functional ability, blood pressure, weight, body mass index, and mortality. Adverse events will be recorded with specific interest on cardiovascular endpoints such as atrial fibrillation and heart failure. Discussion: The combined analysis of participants in the IEMO 80-plus thyroid trial with the participants aged over 80 in the TRUST trial will provide the largest experimental evidence base on multimodal effects of levothyroxine treatment in 80-plus persons to date

Studies in mineral metabolism. XXXII. The effect of different forms of sulphur in the diet upon the growth and wool production of sheep

(1) Details are presented of an experiment on the effects of sulphur and of compounds containing sulphur on the food consumption, weight increase, wool yield and disease of young wethers kept on a production ration for two years. (2) The sheep were fed in individual feeding boxes except for the hay which was given ad lib. (3) The supplements given were dosed daily except Sundays and were given as follows:-Group I: No supplement. Group II: Cystine. Group III: Sulphates. Group IV: KCNS. Group V: 5 gm. sulphur. Group VI: •12 gm. sulphur. (4) No significant effects of the supplements on the sheep could be detected after 12 months' supplementary feeding nor did the experimental groups differ significantly from the control group at the end of the experimental period. (5) The supplement of cystine had no effect on the quantity of wool produced. (6) The mortality and disease due to the presence of urinary calculi were apparently not associated with the supplements. (7) The analyses of the wool will be reported on in due course.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The implementation of wideband 90° hybrids on non-optimal substrates

A new technique to implement wideband 90° hybrid coupling profiles on non-optimal substrate configurations is presented. The technique uses an impedance taper over the whole length of the hybrid to remove the restriction of a substrate defined maximum coupling coefficient at crossover, thus resulting in much more flexibility for the implementation of hybrids on integrated printed circuit boards. The choice of board thicknesses and material type no longer needs to be dominated by the hybrid, but can be optimized for other components or priorities. The flexibility provided by the technique is shown in the implementation of a 2–18 GHz hybrid on a large range of substrate thicknesses as well as on a non-optimal substrate material, for which acceptable measured performance is still obtained.http://wileyonlinelibrary.com/iet-elam2022Electrical, Electronic and Computer Engineerin

Experimental simulation of retrodirective cross-eye jamming

Experimental measurements that accurately simulate the effect of a retrodirective cross-eye jammer on a monopulse radar are described. The accuracy of a recently published extended analysis of retrodirective cross-eye jamming and the limitations of the conventional phase-front analysis of cross-eye jamming are illustrated by the experiments.The Armaments Corporation of South Africa (Armscor) and the National Research Foundation (NRF).http://ieeexplore.ieee.org/ai201