Interactions between toothbrush and toothpaste particles during simulated abrasive cleaning

Most people clean their teeth using toothpaste, consisting of abrasive particles in a carrier fluid, and a filament based toothbrush to remove plaque and stain. In order to optimise cleaning efficiency it is important to understand how toothbrush filaments, abrasive particles and fluid interact in a tooth cleaning contact. Work has been carried out to visualise, simulate, and model the processes in teeth cleaning. Laboratory cleaning contacts were created between a toothbrush and a transparent surface. Video and short duration flash photography were used to study the processes by which a toothbrush traps abrasive particles, loads them against the counterface, and removes material. Small abrasive particles tend to be trapped at the contact between the filament tip and the counterface, whilst larger particles are trapped by clumps of filaments or at the contact with the side of a bent filament. Measurements of brush friction force were recorded during cleaning for a range of operating conditions. The presence of abrasive particles in the cleaning mixture increased the coefficient of friction, but the absolute particle concentration showed a lesser effect. It is surmised that only a few particles carry any load and cause any abrasion; increasing the particle concentration does not directly increase the number of load bearing particles. Abrasive scratch tests were also carried out, using PMMA as a wearing substrate. The scratches produced during these tests were studied. The microscopy images were used to deduce how the filaments deflect and drag, and how particles are trapped by filaments and scratch the surface. Again, it was observed that few of the brush filaments loaded particles to produce scratches, and that when a filament changes direction of travel the trapped particle is lost. Results of these studies were used to develop both qualitative and quantitative models of the process by which material is removed in teeth cleaning. The quantitative model contains, by necessity, several empirical factors, but nonetheless predictions compare well with in vitro wear results from the literature. The results were also used to draw some broad conclusions on appropriate brushing techniques for optimum tooth cleaning

Research Notes: Agriculture Canada and United States Department of Agriculture

In an increase plot of foundation seeds of Harosoy in 1957 at Urbana, a number of Harosoy-type plants were found with flowers of a deeper red than the normal purple (P). The color is best described as magenta (M). This mutant was added to the Genetic Type Collection as T235

Mathematical modelling of tissue-engineering angiogenesis

We present a mathematical model for the vascularisation of a porous scaffold following implantation in vivo. The model is given as a set of coupled non-linear ordinary differential equations (ODEs) which describe the evolution in time of the amounts of the different tissue constituents inside the scaffold. Bifurcation analyses reveal how the extent of scaffold vascularisation changes as a function of the parameter values. For example, it is shown how the loss of seeded cells arising from slow infiltration of vascular tissue can be overcome using a prevascularisation strategy consisting of seeding the scaffold with vascular cells. Using certain assumptions it is shown how the system can be simplified to one which is partially tractable and for which some analysis is given. Limited comparison is also given of the model solutions with experimental data from the chick chorioallantoic membrane (CAM) assay

Tissue engineering and ENT surgery

Tissue engineering is the development of biological substitutes for the repair and regeneration of damaged tissues. We explain the principles of this emerging field of biotechology. The present and potential applications of tissue engineering technologies in ENT surgery are then reviewed

Evidence for strong evolution of the cosmic star formation density at high redshift

Deep HST/ACS and VLT/ISAAC data of the GOODS-South field were used to look for high-redshift galaxies in the rest-frame UV wavelength range and to study the evolution of the cosmic star-formation density at z~7. The GOODS-South area was surveyed down to a limiting magnitude of about (J+Ks)=25.5 looking for drop-out objects in the z ACS filter. The large sampled area would allow for the detection of galaxies which are 20 times less numerous and 1-2 magnitudes brighter than similar studies using HST/NICMOS near-IR data. Two objects were initially selected as promising candidates of galaxies at z~7, but have subsequently been dismissed and identified as Galactic brown dwarfs through a detailed analysis of their morphology and Spitzer colors, as well as through spectroscopic information. As a consequence, we conclude that there are no galaxies at z~7 down to our limiting magnitude in the field we investigated. Our non detection of galaxies at z~7 provides clear evidence for a strong evolution of the luminosity function between z=6 and z=7, i.e. over a time interval of only ~170 Myr. Our constraints also provide evidence for a significant decline of the total star formation rate at z=7, which must be less than 40% of that at z=3 and 40-80% of that at z=6. We also derive an upper limit to the ionizing flux at z=7, which is only marginally consistent with that required to completely ionize the Universe.Comment: 11 pages, A&A, in press. New version after proof correctio

Hearing the patient voice for persistent pain intervention development: recommendations for using a bespoke online discussion forum for qualitative data collection

Introduction Understanding patients’ experiences is important when developing interventions for people living with persistent pain. Interviews and focus groups are frequently used to capture beliefs, views, and perspectives. These methods often require a commitment to a predetermined date and time that may present a barrier to participation. An asynchronous online discussion forum, specifically designed for research purposes, provides an alternative and potentially more accessible method for participation. In this article we discuss a bespoke online discussion forum, the Q-PROMPPT blog, as a case example. Methods We describe how we developed the Q-PROMPPT blog, with patient and public involvement, and its use as an innovative method for qualitative data collection in the context of developing an intervention for patients prescribed opioids for persistent pain. Drawing on our experiences we discuss the following areas: planning and design, participant recruitment and registration, and participant experience and engagement. Results We identify and address key concerns for each area of the Q-PROMPPT blog: planning and design: choosing software, assigning roles, designing the interface to promote usability; recruitment of participants: recruiting eligible participants, participant anonymity; participant experience and engagement: mitigating risk of harm, facilitating discussions, planning for forum close. Conclusion Based on our lessons learnt, we outline recommendations for using a bespoke online discussion forum as a qualitative method to inform intervention development for people living with persistent pain. These include collaboration with information communication technology teams, co-design with patient and public partners, minimising risk of imposter participants and developing trust and online community identity

Effect of tanniniferous browse meal on nematode faecal egg counts and internal parasite burdens in sheep and goats

The effect of tanniniferous browse meal on faecal egg counts (FEC) and intestinal worm burdens was investigated in sheep and goats infested experimentally with gastrointestinal nematodes. Initially, leaves of different browse tree species were assayed for condensed tannin (CT) content using a colorimetric method to determine concentration and seasonal variations. The level of CT in the leaves ranged between 58 – 283 g/kg dry matter. Seasonal changes in CT levels were influenced by stage of leaf maturity with peak levels after the wet season in June. Leaves of Acacia polyacantha had the highest tannin concentration and were used to test their anthelmintic effect in goats and sheep infested with the nematodes in two separate feeding trials. In Trial 1 an acacia leaf meal supplement (AMS) was offered at 100 – 130 g/animal/day for 20 days to growing Small East African goats to investigate its effect on FEC and worm burden. Mean FEC and worm burden of the AMS-fed group were respectively 27% and 13% lower than in the control group. Trial 2 was similar to Trial 1 except that AMS was offered for 30 days to growing Black Head Persian sheep at 170 g/animal/day. The sheep receiving AMS showed a slight reduction in FEC (on average 19% lower than the control group) but had no effect on worm burden. The current results substantiated previous reports of a suppressing effect of CT on gastrointestinal nematodes of small ruminants. Although the observed anthelmintic activity of AMS was less than expected, such reductions can have practical epidemiological implications in reducing pasture larval contamination. Further studies are needed under field conditions to evaluate the feasibility of using locally available tanniniferous browse as an alternative to synthetic anthelmintics in reducing worm infestations in small ruminants. South African Journal of Animal Science Vol. 37 (2) 2007: pp. 97-10

Research Notes: Soybean Gene Resources Recently Received from China

Forty soybean cultivars were received from the Peoples Republic of China in a number of exchanges between June 1973 and June 1974. The first eight cultivars that we received were grown in row tests at Harrow, Woodslee and Ridgetown in 1975, along with \u27Harlen,\u27 \u27Harosoy 63,\u27 and \u27Harcar.\u27 These eight, plus the next seven that we received, had been tested in hill plots at Harrow in 1974, along with Hardome, Harlen, Harosoy 63, and \u27Harwood.\u27 The highest and lowest cultivar values are given for each of a number of characteristics within each group of cultivars as an indication of the potential value of the new germplasm

Evolutionary trade-offs of insecticide resistance – the fitness costs associated with target-site mutations in the nAChR of Drosophila melanogaster

The evolution of resistance to drugs and pesticides poses a major threat to human health and food security. Neonicotinoids are highly effective insecticides used to control agricultural pests. They target the insect nicotinic acetylcholine receptor and mutations of the receptor that confer resistance have been slow to develop, with only one field-evolved mutation being reported to date. This is an arginine to threonine substitution at position 81 of the nAChR_β1 subunit in neonicotinoid resistant aphids. To validate the role of R81T in neonicotinoid resistance and to test whether it may confer any significant fitness costs to insects, CRISPR/Cas9 was used to introduce an analogous mutation in the genome of Drosophila melanogaster. Flies carrying R81T showed an increased tolerance (resistance) to neonicotinoid insecticides, accompanied by a significant reduction in fitness. In comparison,flies carrying a deletion of the whole nAChR_α6 subunit, the target-site of spinosyns, showed an increased tolerance to this class of insecticides but presented almost no fitness deficits

Hypersensitivity reactions to human papillomavirus vaccine in Australian schoolgirls: retrospective cohort study

Objective To describe the outcomes of clinical evaluation, skin testing, and vaccine challenge in adolescent schoolgirls with suspected hypersensitivity to the quadrivalent human papillomavirus vaccine introduced in Australian schools in 2007