Neutrino masses and R-parity violation

We review different contributions to the neutrino masses in the context of R-parity violating supersymmetry in a basis independent manner. We comment on the generic spectrum expected in such a scenario comparing different contributions.Comment: Invited brief review for Mod. Phys. Lett. A, 15 pages, uses axodraw.st

Germanium:gallium photoconductors for far infrared heterodyne detection

Highly compensated Ge:Ga photoconductors have been fabricated and evaluated for high bandwidth heterodyne detection. Bandwidths up to 60 MHz have been obtained with corresponding current responsivity of 0.01 A/W

A proposed function for microplications on epithelial cells

PK201

General problems encountered by the postgraduate first-time electron microscopist

PKThis article identifies the main problems encountered by the postgraduate first- time electron microscopist. Areas where difficulties arise occurred in the communication and planning of the project, general specimen preparation, safety in the laboratory, and in the use of the electron microscope facility. It is recommended that all students who wish to use the electron microscope as a research tool should attend a short course in EM organised by the EM unit staff in conjunction with the various academic departments whose students make use of the facility, before embarking on their research topic

Primary fixation of vervet monkey oral epithelium for SEM and TEM

KIMVervet monkey attached gingiva and alveolar mucosa was used to investigate the effect of primary fixative composition and osmolarity on the scanning electron microscope appearance and epithelial cell surface feature density. Primary fixation was obtained using 12 different fixatives with osmolarities varying between 320-2010mOsm followed by further standard SEM processing procedures. All primary fixatives investigated produced acceptably fixed oral epithelium for SEM study, showing all the morphologic features characteristic of either keratinized or non-keratinized oral tissue. Point counting revealed that the density of microvilli of attached gingiva epithelial cells when fixed at 2010mOsm was 72 +/- 8% of the cell surface area. This decreased to 40 +/- 5% when fixed at 320mOsm. Similarly the microplication density of the alveolar mucosa epithelial cells decreased from 70 +/- 5% at 2010mOsm to 43 +/- 7% at 320mOsm. Both these differences proved to be highly significan

“My supervisor is so busy…”. Informal spaces for postgraduate learning in the Health Sciences.

This descriptive study investigates a one-on-one writing consultancy as an informal learning space, formed to assist postgraduate research students (PRS) with thesis writing.  The consultancy was held monthly on Sundays and appointments booked for up to one hour. During that time writing problems were identified and recommendations made to overcome these. Over the nine months 52 consults were held with 23 PhDs and 21 Master’s candidates, the remaining consults were for non-degree writing purposes.  Consults proved dichotomous with advice sought for both writing and non-writing related issues. Conspicuous were findings indicative of the high workloads carried by supervisory staff which thwarted PRS interaction.  The one-on-one consultancy has many characteristics of alternative research-related spaces used elsewhere to provide PRS support. It is suggested that informal learning spaces, similar to the one-on-one writing consultancy, be investigated as a way to support PRSs and improve their throughput numbers. 

Publication rate of 309 MMed dissertations submitted between 1996 and 2017: Can registrars fulfil HPCSA Form 57 MED amendments?

Background. The recent amendment to the Health Professions Council of South Africa (HPCSA) Form 57 MED allows specialist registration on publication of the compulsory MMed research assignment in an accredited journal. No data exist on the conversion rate of MMed dissertations to publication.Objectives. To establish conversion rates of MMed dissertations to accredited publications. Associated variables arising from the publishing exercise were also investigated.Methods. A total of 309 MMed dissertations, submitted between 1996 and 2017, were downloaded from the public domain. Each dissertation was recorded as to format, submission year, awarding university and clinical discipline. Electronic searches determined publication outcomes. Journal title, accreditation status, year of publication, registrar position on author ranking and publication type were extracted for each output. Descriptive analysis was undertaken and, where appropriate, Fisher’s exact test at p>0.05 was used to establish statistical significance.Results. A total of 116 dissertations were published at an overall conversion rate of 37.5%, culminating in 136 outputs. Publication-ready dissertations had a significantly higher conversion rate (60.3%) than monographs (30.5%) (p>0.0001). All but 6 of the 80 publishing journals were accredited. SAMJ was the journal of choice for 13% of papers. The registrar was the first author in the majority of publications. In the case of monographs, 66% were published after dissertation submission compared with 50% of publication-ready formats.Conclusions. Conversion of the South African MMed dissertation into a journal-accredited scientific article was achieved in 60.3% of publication-ready-format submissions, suggesting that the HPCSA amendment facilitating specialist registration is attainable. Retrospective reviews of dissertations provide valuable insights to improve understanding of the contentious issue of the registrar research requirement that permits specialist registration

Bonding agents: adhesive layer thickness and retention to cavity surfaces with time

KIMThis study assessed bonding agent thickness, cover and the influence of long-term storage on bonding agent retention to enamel and dentine surfaces in cut occlusal cavities in 46 human molar teeth. Two specimens were etched and set aside. The remaining specimens were divided into two equal groups and treated with either Optibond or Scotchbond Multipurpose Plus (SMPP) up to the adhesive stage. Thereafter two specimens from each group were stored for 0, 1, 3, 7 and 14 days and 1, 2, 3, 6 and 12 months in 1% NaCl. After storage the cavity surfaces were examined in a scanning electron microscope (SEM) and scored as to bonding agent cover. One specimen from each treatment was then embedded in resin, two sections prepared midway through each cavity, polished and re-examined in the SEM to measure bonding agent thickness at 13 sites along the cavity surface. Both bonding agents showed highly variable and significant (P < 0.05) bonding agent cover and layer thickness according to cavity site, SMPP more so than Optibond. Pooling of SMPP adhesive was apparent in cavity angles. Mean film thickness was significantly different between Optibond (221 +/- 130 microns) and SMPP (118 +/- 106 microns). There was no significant difference in bonding agent thickness between long- and short-term storage

Microscope observations of ART excavated cavities and restorations

KIMThis in vitro light and scanning electron microscope study examined 39 extracted tooth specimens, hand excavated and restored according to atraumatic restorative treatment (ART), using 'press finger', by 'skilled' and 'novice' operators. Surface features of five excavated cavities, 12 restoration surfaces and the tooth restoration relationships of 22 bisected restored tooth crowns were examined to better understand the clinical effect of the technique. Hand-excavated cavity surfaces were rough with a complex surface arrangement of grooves, crevices, ridges, furrows and overhangs. Enamel and dentine were covered with debris except where surface fractures exposed enamel prisms and occluded dentinal tubules. Ten of the 22 bisected restored specimens had large voids (1-3 mm in length) within the glass-ionomer cement (GIC) restoration or at the tooth-restoration interface. Smaller bubbles (< 50 microns) and irregular shaped inclusions were common in all restorations. Adaptation of the GIC to the cavity margin was extremely variable and easily distinguished from the effects of dehydration shrinkage. It is thought that cavity surface irregularities could cause placement problems making it difficult to adapt the GIC to cavity peripheries. While 'press finger' enabled excellent penetration of GIC into fissures, the technique left restoration surfaces rough. At low magnification, surfaces were irregular; at magnifications higher than X500 scratches, pits, porosities, chipping and voids were evident. However, the 'press finger' technique was able to merge the GIC to a fine edge on the occlusal surface so that the restoration margin was not obvious. No apparent difference was found between the restorations placed by the 'skilled' and 'novice' operators. Tooth-restoration relationships in the ART approach are entirely different to those of traditional restorative techniques. The ART approach requires skill, diligence and comprehension to be undertaken correctly

Experimental marginal leakage around dental amalgams placed in artificial cavities

Experimental marginal leakage of high- and low-Cu amalgam restorations placed in acrylic teeth, where the cavities were untreated or painted with denatured collagen and/or a CaP slurry, was assessed after specimens were stored in a 1% NaCl solution for ten days and for one yr. All specimens stored for ten days showed severe marginal leakage. High- and low-Cu amalgam restorations placed in untreated acrylic teeth cavities formed seals after a storage period of one yr, indicating that these materials are able to form a seal without interacting with a natural tooth cavity interface. Cavities treated with denatured collagen also formed seals in the long-term group. It was apparent that, when the CaP slurry was used, generally more leakage resulted after the year's storage period than when amalgam restorations were placed in uncoated acrylic cavity surfaces or in those painted with denatured collagen.TS2016