5,719 research outputs found
Probing Status Quo Bias in Dentistry
The status quo bias in dentistry refers to a practitioner's preference for certain treatment modalities and resistance to contemplating the need for a change. Lack of updating skills and amending their work routine accordingly can result in them providing treatment that is dated or even totally obsolete. It could even be detrimental to their patient's oral health and open them up to the risk of litigation. The concept of Continuing Professional Development (CPD) was introduced to try enforce clinicians to improve their knowledge and skills, and keep abreast of current best practice recommendations. However, it should not be seen as a mere points collecting exercise that has little effect on bringing about changes in their work. Dentists need to continually review their work, and make adjustments when necessary in order to do better and be better. Only then canthey claim to be acting in their patients’ best interest and fulfilling their duty of beneficence
Phases of granular segregation in a binary mixture
We present results from an extensive experimental investigation into granular
segregation of a shallow binary mixture in which particles are driven by
frictional interactions with the surface of a vibrating horizontal tray. Three
distinct phases of the mixture are established viz; binary gas (unsegregated),
segregation liquid and segregation crystal. Their ranges of existence are
mapped out as a function of the system's primary control parameters using a
number of measures based on Voronoi tessellation. We study the associated
transitions and show that segregation can be suppressed is the total filling
fraction of the granular layer, , is decreased below a critical value,
, or if the dimensionless acceleration of the driving, , is
increased above a value .Comment: 12 pages, 12 figures, submitted to Phys. Rev.
Contrast in chloride exclusion between two grapevine genotypes and its variation in their hybrid progeny
Potted grapevines of 140 Ruggeri (Vitis berlandieri × Vitis rupestris), a good Cl− excluder, and K 51-40 (Vitis champinii × Vitis riparia ‘Gloire’), a poor Cl− excluder, and of a family obtained by crossing the two genotypes, were used to examine the inheritance of Cl− exclusion. Rooted leaves were then used to further investigate the mechanism for Cl− exclusion in 140 Ruggeri. In both a potting mix trial (plants watered with 50 mM Cl−) and a solution culture trial (plants grown in 25 mM Cl−), the variation in Cl− accumulation was continuous, indicating multiple rather than single gene control for Cl− exclusion between hybrids within the family. Upper limits of 42% and 35% of the phenotypic variation in Cl− concentration could be attributed to heritable sources in the potting mix and solution culture trials, respectively. Chloride transport in roots of rooted leaves of both genotypes appeared to be via the symplastic pathway, since addition of 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer, revealed no obvious PTS fluorescence in the laminae of either genotype, despite significant accumulation of Cl− in laminae of K 51-40 during the PTS uptake period. There was no significant difference in either unidirectional 36Cl− flux (10 min) or 36Cl− uptake (3 h) into roots of rooted leaves exposed to 5, 10, or 25 mM Cl−. However, the percentage of 36Cl− transported to the lamina (3 h) was significantly lower in 140 Ruggeri than in K 51-40, supporting reduced Cl− loading into xylem and implicating the root stele in the Cl− exclusion mechanism
Nitrogen transactions along the digestive tract of lambs concurrently infected with Trichostrongylus colubriformis and Ostertagia circumcincta
Twelve lambs, paired on the basis of live weight, were cannulated in the abomasum, in the proximal jejunum approximately 4 m distal to the pylorus and in the terminal ileum. Six were infected with 3000 Trichostrongylus colubriformis and 3000 Ostertagia circumcincta larvae each day for 18 weeks and the remainder were pair-fed to individual infected lambs. All animals were offered ryegrass (Lolium perenne)–white clover (Trifolium repens) pasture, cut daily. Dry matter (DM) intake, live weight, faecal egg concentration, plasma pepsinogen and plasma protein concentrations were measured weekly. During weeks 7 and 17 after commencement of infection, the flow of digesta along the gastrointestinal tract was measured together with enteric plasma loss and true digestion and absorption of ¹²⁵I-labelled albumin in the small intestine. DM intake was depressed by parasitism, being 1331, (se 70), 423 (se 32) and 529 (se 52) g/d during weeks 3, 7 and 17 respectively. The flow of nitrogen at the proximal jejunum and in faeces was increased by parasitism during week 7 and at the abomasum and ileum during week 17. Plasma protein-N loss (g/d) into the gastrointestinal tract was 0.68 (se 0.091) and 1.97 (se 0.139) during week 7, and 0.85 (se0.158) and 1.96 (se 0.396) during week 17, in control and infected sheep respectively. True digestion and absorption of albumin in the proximal small intestine, the site of infection, was very low (mean 0.08) and was not affected by parasitism. Between the abomasum and terminal ileum absorption of albumin was high (mean 0.87) and again was not affected by parasitism. It was calculated that of the total increase in endogenous protein passing from the ileum tract as a result of infection, plasma protein comprised only a small percentage (10–36%). The major proportion of digestion and absorption of protein occurred in the distal small intestine beyond the site of infection and was not affected by infection
Variation between and within grapevine families in reaction to leaf inoculation with downy mildew sporangia under controlled conditions
Vine reaction to downy mildew [Plasmopara viticola (Berk. & Curt.) Berl. & de Toni] inoculation was investigated between and within seven full-sib grapevine families under controlled culture conditions. Families were generated by crossing resistant x susceptible and susceptible x susceptible genotypes. Leaf infection following downy mildew inoculation was assessed using cultured leafed single node cuttings under controlled conditions. The severity of disease infection 7 days after inoculation was based on the expression of leaf chlorosis and sporulation symptoms using a 1 to 9 scale where a score of 1 meant there was no visible sign of infection and 9 meant > 80 % of the leaf area was infected. A measure of the hypersensitive response (discrete necrotic spots) was also used to rank vine reaction to inoculation. Hybrids within families varied widely in their reaction to inoculation. Any hybrid that received a mean symptom expression score ≤ 3, which was equivalent to or less than that assigned to 'Chambourcin', was classified as downy mildew resistant. The proportion of vines within families scored as resistant ranged from 4.6 to 22.5 % and from 4.6 to 47.4 % for leaf chlorosis and sporulation, respectively, between crosses. There was a strong correlation between leaf chlorosis and sporulation expression within each family (r2 ranged from 0.6 to 0.8). The number of resistant hybrids selected within families by the combined symptoms of leaf chlorosis and sporulation ranged from 3 to 7. Depending on family, segregation of resistant to susceptible phenotypes based on symptoms of leaf chlorosis and sporulation fitted 1:15, 1:7, 1:3 or 1:1 ratios. Segregation for hypersensitive reaction (HR) to non-HR fitted 1:1, 1:2 or 1:3 ratios within families. Hybrids that displayed the HR had mean scores for leaf chlorosis and sporulation less than those not displaying the necrotic spots characteristic of the reaction in four of the families investigated. The results are discussed in terms of the inheritance of resistance and the development of a strategy for future breeding.
Site percolation and random walks on d-dimensional Kagome lattices
The site percolation problem is studied on d-dimensional generalisations of
the Kagome' lattice. These lattices are isotropic and have the same
coordination number q as the hyper-cubic lattices in d dimensions, namely q=2d.
The site percolation thresholds are calculated numerically for d= 3, 4, 5, and
6. The scaling of these thresholds as a function of dimension d, or
alternatively q, is different than for hypercubic lattices: p_c ~ 2/q instead
of p_c ~ 1/(q-1). The latter is the Bethe approximation, which is usually
assumed to hold for all lattices in high dimensions. A series expansion is
calculated, in order to understand the different behaviour of the Kagome'
lattice. The return probability of a random walker on these lattices is also
shown to scale as 2/q. For bond percolation on d-dimensional diamond lattices
these results imply p_c ~ 1/(q-1).Comment: 11 pages, LaTeX, 8 figures (EPS format), submitted to J. Phys.
A method using leafed single-node cuttings to evaluate downy mildew resistance in grapevine
A method using leafed single-node cuttings, incubated at 25 ± 2 °C and 100 % humidity, was examined to screen grapevine genotypes for resistance to downy mildew (Plasmopara viticola (Bert. & Curt.) Berl. & de Toni). Cuttings were taken at the 4th, 5th and 6th nodes back from apices of actively growing shoots. Disease symptoms, namely chlorosis, sporulation and necrosis, were observed on the leaves of cuttings within 6 days of incubation after inoculation. Based on chlorosis and sporulation, genotypes were ranked from highly susceptible to resistant in the order of Sultana, M46-32 (Bicane x Villard blanc), Joannes Seyve 23.416, Marroo Seedless and Chambourcin. The expressions of both symptoms increased with the concentration of inocula applied to leaves (1 x 105 and 5 x 104 sporangia per ml), but the overall genotypic ranking was unaltered. The third symptom of leaf necrosis occurred on infected leaves either as progressively enlarging dead areas or as smaller localised necrotic spots. The latter has been call ed the ‘necrotic response’ symptom and its expression depended on genotype, although its value for separating or ranking genotypes was unreliable. Leaf chlorosis was associated with leaf sporulation (r2=0.41-0.47). Genotypes with necrotic response exhibited reduced leaf chlorosis and sporulation. A comparison between this new leafed singlenode cutting method and a previously published leaf disc method indicated it was more reliable for separating genotypes for downy mildew resistance.
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