The role of trade literature in the communication system

Bibliometric methods in general undervalue technological research. This study examines the relation in literature between technological/industrial journals and scientific journals in the case of the plastics industry and polymer science. Trade-journals cannot be used in a straightforward bibliometric manner, but can be an aid in mapping the different groups and reveal the lsquohiddenrsquo communication between technological and scientific communities

Cross sections of proton-induced reactions on 152Gd, 155Gd and 159Tb with emphasis on the production of selected Tb radionuclides

Cross sections are presented for various Dy, Tb and Gd radionuclides produced in the proton bombardment of 159Tb as well as for the reactions 152Gd(p,4n)149Tb and 155Gd(p,4n)152Tb up to 66 MeV. The experimental excitation functions are compared with theoretical predictions by means of the geometrydependent hybrid (GDH) model as implemented in the code ALICE/ASH, as well as with values from the TENDL-2012 library and previous literature experimental data, where available. Physical yields have been derived for the production of some of the medically important radioterbiums, namely 149Tb (radionuclide therapy), 152Tb (PET) and 155Tb (SPECT). The indirect production of high-purity 155Tb via the decay of its precursor 155Dy is reported. The possibility of a large-scale production facility based on a commercial 70 MeV cyclotron is also discussed

Knelpunte in die westerse gesin as gevolg van gesinsverandering

Ons leef in ’n eeu wat deur snelle en toenemende verandering gekenmerk word. Hierdie veranderinge en nuwe ontwikkelings is egter nie net tot die tegnologie beperk nie maar vind ook in die maatskaplike lewe plaas. Die veranderinge op maatskaplike gebied is egter nie so vinnig en skouspelagtig soos op die tegnologiese ge­ bied nie, en dit word eers oor ’n lang tydperk geleidelik sigbaar. In der waarheid word hierdie veranderinge eers waargeneem as dit m et die maatskaplike toestande van die era wat dit voorafgegaan het, vergelyk word

Die toekoms van die sosiale wetenskappe in die nuwe Suid-Afrika

The development of the social sciences has been closely linked to increasing cultural contact and the emergence of social problems in society. The question of the applicability of the body of knowledge in the social sciences for the improvement of conditions in society was raised particularly after the Industrial Revolution when social conditions began to change drastically and social problems increasingly made their appearance. This alignment with applicability finally resulted in the development of the so called helping professions and the acceptance in formal organisations of the status of professional social scientists. The relevance of the social sciences will increase in the New South Africa. This statement is based on the fact that a successful future political dispensation will not automatically mean that all social problems will immediately disappear. In fact, the prognosis - based on trends in the past as well as the present is that there will be an escalation of social problems such as urbanization and the growth of squatter camps, breakdown of schools and the disintegration of the family. Social scientists will have to play an important role in handling these problems. It would therefore be extremely shortsighted if universities should fail to provide a thorough training for social scientist

Diabetes mellitus, pulmonary tuberculosis and chronic calcific pancreatitis revisited

The prevalence of chronic calcific pancreatitis (CCP) was determined in 25 successive patients with both diabetes mellitus and newly diagnosed pulmonary tuberculosis. Twenty patients (80%) were alcoholics and all were black. Of these, 9 (45%) had CCP. In only 3 of these 9 patients was the history compatible with the condition diagnosed. Clinical steatorrhoea was absent in the patients with CCP. PulmonarY tuberculosis was extensive with major involvement of three or more lung zones in 36% of patients. Mainly basal involvement of the lungs was present in 8% of patients

Ophthalmoscopy versus non-mydriatic fundus photography in the detection of diabetic retinopathy in black patients

The contribution of non-mydriatic fundus photography in the detection of diabetic retinopathy before and after dilatation of the pupils in black diabetics was investigated and compared with direct ophthalmoscopy. Eighty-six patients were examined and good-quality photographs were obtained for 54,7% of eyes before and 86,6% of eyes after dilatation. Photographically documented retinopathy was detected by ophthalmoscopy in only 64,7% of eyes. The two methods were concordant for the presence of retinopathy in 62,2% of eyes before and 56,9% of eyes after dilatation. Photography through dilated pupils also i.mproved the rate of detection of diabetic retinopathy from 24% to 30%. The 45° non-mydriatic fundus camera was found to be a valuable adjunct in the detection of diabetic retinopathy in a busy diabetic clinic

Neutron activation as an independent indicator of expected total yield in the production of 82Sr and 68Ge with 66 MeV protons

Introduction A method based on neutron activation is being developed to assist in resolving discrepancies between the expected yield and actual yield of radionuclides produced with the vertical-beam target station (VBTS) at iThemba LABS. The VBTS is routinely employed for multi-Ci batch productions of the radionuclide pairs 22Na/68Ga and 82Sr/68Ga using standardized natMg/natGa and natRb/natGa tandem targets, respectively [1]. The metal-clad target discs are bombarded with a primary beam of 66 MeV protons at an intensity of nominally 250 µA. The encapsulation materials are either Nb (for Mg and Ga) or stainless steel (for Rb) which serve to contain the molten target materials during bombardment and act as a barrier to the high-velocity cooling water which surrounds the targets in a 4π geometry. The natRb/natGa targets are typically bombarded according to a two-week cycle while natMg/natGa targets are bombarded on an ad-hoc basis, depending on a somewhat unpredictable 22Na demand. A too-large deviation between expected yield and actual yield has at times plagued this programme. These deviations can manifest both as an apparent loss or an apparent gain (relative to the expected yield) by up to about 15% in either direction. The resulting uncertainty of up to 30% (in the worst case) from one production batch to another can be costly and is unacceptable in a large-scale production regimen. This phenomenon is believed to be brought about by two types of problems: (1) Production losses, e.g. during the radio-chemical separation process or incomplete recovery of activated target material during the decapsulation step. (2) Incorrect values obtained for the accumulated proton charge. A problem of type (1) will always result in a loss of yield. A problem of type (2) can manifest as an apparent loss or gain. In an effort to get a handle on this second type of problem, neutron activation of suitable material samples, embedded in a target holder, is being investigated as an independent indicator of the total yield. For this purpose, samples of Co, Mn, Ni and Zn were activated during production runs and Co was found to be the most appropriate. Preliminary results will be presented after first discussing why the determination of the accumulated pro-ton charge is a problem with the VBTS. Materials and Methods The VBTS consists of a central region in which a target holder is located during bombardment as well as two half-cylindrical radiation shields which completely surround the target. The shields can be moved away from the central region on dedicated rails, e.g. when repairs or maintenance is required. FIGURE 1 shows the VBTS with the shields moved to the “open” position. As some components of the station are located below the vault floor, with the target position near floor level, it proved difficult to electrically isolate the VBTS as was done for the two horizontal-beam target stations at iThemba LABS [1]. The VBTS does not act as a Faraday cup like the other target stations. Instead, the beam current and accumulated charge is measured by means of a calibrated capacitive probe [1,2]. There appears to be a variation in the response of the capacitive probe, sensitive to the beam microstructure, in particular a dependence on the beam packet length. This problem is not yet fully resolved. FIGURE 2 (a) shows the beamstop of a VBTS target holder with several Co samples mounted on the outside as well as one each of Ni, Mn and Zn. The samples are small “tablets” with a 10 mm diameter and 1 mm thickness. The reactions of interest are 59Co(n,γ)60Co, 59Co(n,3n)57Co, nat-Ni(n,X)60Co, natNi(n,X)57Co, natZn(n,X)65Zn and 55Mn(n,2n)54Mn. The relevant half-lives are 60Co(5.271 a), 57Co(271.8 d), 65Zn(244.3 d) and 54Mn(312.2 d). The half-life should be long compared to the two-week cycle in order to reduce the dependence on the exact beam history, which is very fragmented over any production period. In this respect, 60Co is considered to be particularly attractive as its long half-life of more than 5 years leads to a negligible effect by the beam history. Note that the tandem targets, shown in FIGURE 2 (b), are mounted just upstream of the beamstop – in fact, the targets and beamstop form a single unit before being fitted into the target holder. At the end of bombardment, all samples were assayed for their characteristic γ-emissions using standard off-line γ-ray spectrometry with an HPGe detector connected to a Genie 2000 MCA. Calculations of the neutron fluence density in the central sample volume on the beamstop were also performed using the Monte Carlo radiation transport code MCNPX. For these calculations, the entire VBTS, a Rb/Ga target and the vault walls were included in the model. Results and Conclusion All samples activated significantly – copious amounts of 60Co were detected in the Co discs after a two-week run. The neutron fluence density for the case of a 250 µA, 66 MeV proton beam on a natRb/natGa tandem target is shown in FIGURE 3. The dominance of low-energy neutrons is evident, which is in part due to the large amount of paraffin-wax shielding material in close proximity to the target. While reactions such as the (n,2n) and (n,3n) would be sensitive to the more energetic part of the neutron spectrum, the (n,γ) capture reaction benefits from the large low-energy component. This explains the copious amounts of 60Co formed. It was therefore decided to only retain the central Co sample for subsequent bombardments, as shown in FIGURE 4. The first results are shown in TABLE 1. The accumulated charge as obtained from the capacitive probe (Q), the specific 60Co activity (A) at the end of bombardment (EOB), and their ratio (A/Q) are presented in the table, together with the deviation of individual ratios relative to their average for the case of the Mg/Ga tandem tar-gets only. Note that all samples were counted until the statistical uncertainties were negligible. Any systematic uncertainties are ignored at this stage as they are considered to remain the same from one batch production to another. For the sake of argument, the average value of the ratio is taken as the expected value. A positive deviation of the A/Q value is then indicative of a too-small value of the accumulated charge obtained from the capacitive probe, leading to a corresponding overproduction. Likewise, a negative value is indicative of a too-large value of the accumulated charge, leading to a corresponding underproduction. It is certainly true that the data in TABLE 1 are currently very limited. It is envisaged, however, that with time the growing database of values will assist in reducing the uncertainty in determining the accumulated charge and reduce the discrepancies between predicted and actual yields significantly. TABLE 1 illuminates the underlying problem satisfactorily. The four Mg/Ga tandem target bombardments, on identical targetry, were performed successively. The neutron activation correlates well the with actual yields, pointing directly to the current integration as the main source of error. The method already proves to be useful. An indication of an over or underprediction can be obtained prior to the target processing by recovering and measuring the Co disc. This in-formation can be used to make a decision concerning the present batch production and/or the subsequent one. One can either add beam to the present production target and/or in-crease/reduce the total beam on the subsequent production target to compensate for an expected overproduction or shortfall. In conclusion, we would like to stress that the capacitive probes show great promise and that better understanding and/or possibly some development of their signal processing algorithm may improve their ability to measure the accumulated charge to the desired accuracy. Segmented capacitive probes used at iThemba LABS and elsewhere for beam position measurement [1,3] are not affected by beam microstructure as only the ratios of the signal strengths on the different sectors are important. In this case, changes in response affect all sec-tors equally and the ratios are unaffected

Academic and quantitative literacy in higher education: Relationship with cognate school-leaving subjects

Academic and quantitative literacies (AQL) are essential to success in higher education. These literacies are largely not explicitly taught, but acquired indirectly, mostly through practices in various school subjects. The National Benchmark Tests (NBT) Project assesses students’ AQL competencies to assist in identifying students who need support, with placement into appropriate programmes and with curriculum development. We analyse the performance on the NBT AQL test of students who took the school-leaving examinations in Mathematics, Mathematical Literacy, English Home Language and English First Additional Language. We use the subject choice as a representation of the level of a candidate’s quantitative competence and language proficiency respectively, and investigate the relative contributions made by these subject choices to a student’s AQL. Students who paired Mathematics with English as Home Language subject had the statistically significant highest mean AQL score and those who took both English First Additional Language and Mathematical Literacy had the lowest. Language competence has a stronger effect than mathematical competence on AQL. Students who took the subject combination Mathematics and English Home Language at school are better prepared for the academic demands of higher education than their counterparts who took the alternate subjects. Treating these subjects as equivalent to English Home Language and Mathematics for admissions purposes ignores the differences in preparedness of these students