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SUMMARYThe drought tolerance of tea clones in Kenya can be improved by grafting onto appropriate rootstocks, with more susceptible clones showing greater improvement. It appears that drought may have distinct effects on rootstock and scion, with rootstock performance correlated with xylem water potential, while scion performance was correlated with stomatal conductance. Drought tolerance is not the only requirement for a rootstock under Kenyan conditions, however, and the most tolerant rootstocks do not necessarily give the greatest overall yield increase when non-drought years are included.

Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster ( Listeria pathogenicity island 1) of L. monocytogenes . It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes -specific allele of iap , as well as the absence of inlA , inlB , inlC , and daaA . At least two of the virulence cluster genes, hly and plcA , which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes ( lin0198 , lin0372 , lin0419 , lin0558 , lin1068 , lin1073 , lin1074 , lin2454 , and lin2693 ) and noncoding intergenic regions ( lin0454-lin0455 and nadA-lin2134 ) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.

Thirty-six patients aged 15-74 with palatal dental erosion where the aetiology was unclear were investigated for gastro-oesophageal reflux. Ten subjects without symptoms of reflux or palatal erosion acted as controls. Distal and proximal oesophageal reflux were measured over 24 hours by dual channel antimony electrodes. Oral pH was measured simultaneously over the same period by a radio-telemetry capsule held palatally in a vacuum formed splint. Data were logged onto two portable digitable recorders. Twenty-three patients (64%) with palatal erosion had pathological gastro-oesophageal reflux compared with standard criteria. More than 4% of the total percentage time that the pH is less than 4 in the distal oesophagus is internationally recognised by gastroenterologists as representing a pathological level of reflux. The median percentage time < pH 4 in the distal oesophagus for these patients was 5.7%, in the proximal oesophagus, pH 4 was 0.5% and pH < 5 was 3.1%. In the mouth, the results for the percentage time that the pH < 5.5 was 0.3% and < 6 was 4.4%. A relationship was observed between the pH < 4 in the distal oesophagus and the mouth pH < 5.5 (r = 0.47, P = 0.002) and pH < 6 (r = 0.34, p = 0.02). There was a relationship between oral acid exposure time pH < 6 and the tooth wear index (r = 0.37, P = 0.01). These results show that gastro-oesophageal reflux is strongly associated with palatal erosion and that some patients presenting with palatal dental erosion should be assessed for gastro-oesophageal reflux as a possible cause, even in the absence of clinical symptoms of reflux.

Pairs of extracted premolar teeth were prepared with MOD cavities reducing the lingual cusp at its base to one of five widths: 1.25-2.25 mm. One of each pair was then restored with one of five adhesive restorative techniques and the weakened cusp of both teeth fractured by a force applied to the cusp at an angle of 30 degrees to the long axis of the tooth. At all cusp widths a layered restorative technique in which the cavities were filled to the enamel-dentine junction with glass-ionomer cement and the enamel replaced by composite, reinforced the weakened cusp more than the other restorative materials tested. This combination of materials to reinforce weakened cusps is worth considering as a cost effective alternative to removing the cusp entirely and making a crown or protecting the cusp with a cuspal coverage gold inlay.

Anorexia and bulimia nervosa (the eating disorders) are potentially life threatening and are becoming more prevalent. This paper reviews the effects of these disorders on dental erosion and reports a study to assess the effects of the eating disorders on the erosion of teeth relating the severity of erosion to factors such as the frequency of self-induced vomiting (SIV). One hundred and twenty-two eating disorder patients and an equal number of age, sex, and social class matched controls were studied. The study population was divided into subgroups according to the eating disorder. All the subgroups had significantly more abnormal toothwear than the controls (P < 0.005), with the differences being most marked in the SIV groups. Further analysis did not find any consistent relationships to the frequency or duration of SIV

Deterioration of reinforced concrete structures is a problem in coastal climates. Most of this deterioration is caused by chloride ingress through the concrete, which results in the corrosion of the reinforcing steel and spalling of the cover concrete. The practice of modeling chloride ingress to understand this deterioration process is increasing as engineers work to improve the durability of concrete. The authors present examples of deteriorated structures, modeling results for new structures and examples of current projects along the coastal LOSSAN rail corridor between Los Angeles and San Diego in San Diego County. The conclusion is that by specifying the addition of fly ash, silica fume and corrosion inhibitors in concrete, subject to temperate marine exposure conditions, we are able to increase the predicted service life of new structures to 100 years.

In this paper we introduce the methodology of using neural networks (nonlinear regressions) as a yield ramp technique for new product introduction. Within a wafer fabrication facility, a large set of manufacturing equipment is used in sequential mode for IC manufacturing. As the technology scales, it is becoming more difficult to detect influential factors associated with specific equipment during a yield ramp. Using multiple iterations of neural networks on subsets of the yield ramp data, we have successfully isolated equipment sets that are most likely to influence yield very early in the yield ramp phase. This allows for a significantly shorter yield learning time.

The effect of the presence of fluoride in toothpaste on tooth wear was investigated in extracted human premolar teeth collected from two geographic areas with different fluoride concentrations in the public water supply. Nine teeth from each area were divided bucco-lingually into matched pairs and subjected to a wear regime in vitro. The regime consisted of 5 minutes immersion in 6% citric acid buffered at pH 3.5, followed by 200 cycles of linear tooth-brushing in a slurry of either a fluoride or a non-fluoride toothpaste, the whole process repeated 720 times. Teeth collected from subjects in Birmingham (public water supply fluoridated at 1 ppm) had a higher fluoride concentration in the surface enamel (P < 0.01) and greater hardness (P < 0.001) than teeth collected from subjects in London (non-fluoridated water supply). The results showed that less wear was produced in the presence of the fluoride toothpaste than in the presence of the non-fluoride toothpaste with an otherwise identical formulation (P < 0.001), and that the amount of tooth wear in vitro was not significantly affected by differences in fluoride concentration and hardness of enamel.

To investigate causative factors of cervical wedge-shaped defect of human teeth and the significance of methods for measurement of the defect.Experimental cervical defects on 9 pairs of premolars were created by cross-brushing, erosion, or fatigue of occlusion force separately or combinedly and measured in depth and area of profile as well as in volume.1. Profile depth of defects caused by three factors separately showed no statistical difference, but the profile depth caused by combining factors was much more than that caused by each individual factor; 2. The hardness of enamel and dentin in defect area was lower than that in normal area of tooth samples; 3. Measurement from one-dimension (depth) and two-dimension (area) showed only low relation in profile depth, however, measured three-dimensionally (volume) there existed moderate relationship.For study of cervical defect, the profile depth is feasible provided that is a large sample group and without equipment for volume measuring; if the sample size is limited and there is sophiscated instrument for volume measuring, the 3-dimensional measurement is the most sensitive one.

It has been suggested that salivary characteristics are important in the progression of erosion. The aim of this investigation was to measure salivary parameters in 22 patients with erosion, 10 with normal (non-pathological) levels of reflux (Group I) and 12 with previously diagnosed pathological levels of gastro-oesophageal reflux (Group II). A further 10 subjects without evidence of erosion and no history of reflux disease acted as controls (Group III). No statistically significant differences in salivary flow rate, buffering power or the concentrations of calcium, phosphorus and fluoride were detected. The results suggest that variation in the characteristics of unstimulated and stimulated saliva collected during waking hours do not have a major role in erosion.

This paper reviews methods to measure tooth wear especially those more recently introduced as a result of improvements in technology. The review searched methods to measure tooth wear and dental erosion from large epidemiological investigations, in vitro and in vivo studies. There seems to be wide variation in techniques used to measure tooth wear and erosion. In vitro techniques may have little direct clinical relevance but can lead to new and more accurate clinical methods. In vivo studies have problems with reference points and accurate validation of the techniques. There is a need for a simple, reliable technique to quantify tooth wear due to erosion.

This paper describes the history and current status of specialization within dental practice in the UK.

Although chronic alcoholism is a very common condition, with potentially harmful consequences for the sufferer, there has been little emphasis in the literature on its effects on the teeth. This study of 37 alcoholic patients showed that their teeth had significantly more wear than age and sex matched controls. The tooth wear was most marked in males, and those whose alcohol consumption was continuous rather than in the form of episodic binges. The wear appeared to be erosive in nature, and in 40% of the sample it affected the palatal surfaces of the upper anterior teeth. It is therefore suggested that general dental practitioners should bear in mind the possibility of chronic alcoholism in cases of unexplained dental erosion.

Computed tomographic (CT) scans were performed after closed reduction of 68 dislocated hips in 53 infants in spica casts with developmental hip dislocation (DDH). Ten measurements were made on the CT scans including acetabular indices and anteversion, hip-abduction angle, lateral and posterior displacement of the femur from the acetabulum, and femoral displacement from a modified Shenton's line drawn from the pubic rami. By using analysis of variance, the correlation of each variable with outcome after reduction was determined, including the development of avascular necrosis or the need for further surgery because of residual dysplasia. None of the variables was predictive of the outcome of persistent hip dysplasia. The subsequent development of avascular necrosis was statistically associated with hip-abduction angles55 degrees as measured on postreduction CT scans, with 20% of the involved hips developing avascular necrosis on subsequent follow-up.

Twenty computed tomographic (CT) scans of infants in spica casts after closed or open reduction for developmental hip dislocation (DDH) were analyzed for intra- and interrater reliability. Ten measurements of infant hip anatomy were assessed by three raters by using standard statistical analysis. All six measurements of acetabular anteversion and lateral or posterior displacement of the femoral metaphysis from the acetabulum or from a modified Shenton's line drawn from the pubic rami demonstrated both intra- and interrater reliability. All four measurements of acetabular structure could not be reliably measured either within or between observers. We also introduced a new measurement based on the principle of Shenton's line to aid in the assessment of femoral-head location after reduction in patients with DDH; this was reliably determined both within and among observers.

At various times after pulse-labeling broad bean (Vicia faba L.) leaflets with 14CO2, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents, whereas those from rinsed peels contained only symplastic contents. Sucrose (Suc)-specific radioactivity peaked (111 GBq mol-1) in palisade cells at 20 min. In contrast, the 14C content and Sucspecific radioactivity were very low in guard cells for 20 min, implying little CO2 incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum Suc-specific radioactivity (204 GBq mol-1) and a high Suc influx rate (0.05 pmol stoma-1 min-1). These and other comparisons implied the presence of (a) multiple Suc pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived Suc in guard-cell walls sufficient to diminish stomatal opening by approximately 3 [mu]m. Factors expected to enhance Suc accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic Suc concentration, which is elevated when mesophyll Suc efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal aperture size by this previously unrecognized mechanism.

At various times after pulse labeling Vicia faba L. leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents whereas those from rinsed peels contained only cytoplastic contents. Sucrose specific radioactivity peaked in palisade cells, 111 GBq{center_dot}mol{sup {minus}1}, at 20 min. In contrast, the {sup 14}C content and sucrose specific radioactivity were very low in guard cells for 20 min, implying little CO{sub 2} incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum sucrose specific radioactivity and a high sucrose influx rate. These and other comparisons implied the presence of (a) multiple sucrose pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived sucrose in guard-cell walls sufficient to diminish stomatal opening by {approximately} 4 {micro}m. Factors expected to enhance sucrose accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic sucrose concentration, which is elevated when mesophyll-sucrose efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal-aperture size by this previously unrecognized mechanism.

The dental profession is becoming increasingly concerned about unacceptable levels of toothwear and there is an impression that the condition is becoming more prevalent. There is, as yet, little epidemiological evidence to illuminate the question and so this study is therefore intended to provide baseline data on the prevalence of toothwear in a sample of the dental attending population of South East England. A degree of toothwear is normal and progresses throughout life. Toothwear which is acceptable in an older age group would not be so with younger patients. It is therefore necessary to designate threshold values of acceptable levels of toothwear for different age groups to reach realistic conclusions about the prevalence of unacceptable levels of toothwear. Of the 1007 patients examined only nine had completely unworn dentitions. More than 93,500 tooth surfaces were examined and of these 5.1% had wear which exceeded the threshold values. Despite increasing the threshold values for the older age groups from those proposed in an earlier study by Smith & Knight (1984), these patients still had higher levels of unacceptable toothwear. There was a slight tendency for men to have more wear than women, but there was no clinically significant relationship between the number of missing posterior teeth and wear of the anterior teeth.

The management of caries, periodontal disease and tooth wear has followed similar patterns over the last 30 years but at different rates. The reduced emphasis on surgery in the treatment of periodontal disease has now caught up with minimum interventive treatment of caries. Tooth wear is still, in my opinion, often over-treated and it is time that the management of tooth wear followed the same pattern.

Experimental cervical defects on 12 pairs of premolar caused by cross-brushing, erosion and occlusal force separately or together were observed under SEM Changes on the surface of cervical defects suggested that the defects were induced by the above three factors combined. It was interesting that various kinds of microcracks were noticed on sections of enamel and dentin at the cervical defect areas made by mimicking occlusal force combined with other factors. The results seemed to indicate that the occlusal force would play an important role on formation of the cervical wedge-shaped defect and that accumulation of the stress caused the hard tissue injured and microcracked.

Nine pairs of premolar from 7 patients were divided into three groups according to different occlusal forces. Every tooth was tested with pH5 or pH7 water bath by an electric toothbrushing machine and an electric occlusal force fatigue machine alternatively. Only the buccal surface of every tooth suffered from brushing test. There were 600 000 strokes of occlusal force fatigue test and/or 800 000 cycles of cross-brushing test for every tooth throughout the experiment with 4 intervals. During every interval, the depth at the profile of the cervical defect on each replica of tested tooth was measured and the shape of every defect was recorded with a computerized Seescan image analysis system. The findings suggested that the occlusal force played an important role in the formation of experimental cervical wedge-shaped defects. Occlusal force alone could produce cervical tooth defect in very slow rate. When the occlusal force associated with acid erosion and tooth-brushing abrasion, the depth of cervical defect increased significantly and the wedge-shaped defects were formed.

summary Various methods of diagnosing occlusal caries have been described, but only visual, clinical examination and radiographic examination are commonly used in dental practice. This laboratory study investigated the ability of 12 examiners to detect the presence or absence of occlusal caries in 48 extracted molar teeth using these two techniques. The presence or absence of caries was subsequently verified by sectioning the teeth. Diagnosis from visual examination was poor, only 48.7% of lesions in dentine being detected. Radiographic diagnosis was better with 62.2% of dentine lesions being found. However, this increase in sensitivity of the diagnosis was accompanied by a decrease in specificity with the number of false positive diagnoses increasing when the radiograph was used. Therefore, although the bite-wing radiograph may be regarded as a safety net for the diagnosis of occlusal caries, it must be interpreted with caution bearing in mind the possibility of false positive diagnoses.

Recently, Kowalczyk et al (2011 Nanotechnology 22 315101) introduced a model for calculating the conductance of an hourglass-shaped nanopore, and the conductance change when DNA is introduced into such a pore. Here, we comment on their model in the context of other literature addressing the same general problem. Existing work includes widespread use of an alternative model, contradicts the authors’ claim that the conductance change should be expected not to vary with pore size, and has frequently utilised access resistance.

Our self-perceptions are all influenced to some extent by the media. The increase in sales of diet plans immediately after Christmas only serves to highlight the fact that many people (consciously or subconsciously) are aware of the effect that advertisements have on our lives. The weight of most people is controlled by a combination of diet and homoeostatic control and remains relatively constant, but weight loss has a more profound and sinister effect for others. Unexplained dental erosion can occasionally be found during dental examinations and, despite careful questioning, a definitive diagnosis may prove elusive. In these patients, once the more common causes of dental erosion have been eliminated, the eating disorders should be considered. In this paper, the effects of psychological conditions affecting the diet on the dentition will be discussed.

In this second article a range of clinical techniques for producing minor axial tooth movement is described, including the simple, cemented metal anterior bite-plane which has proved to be one of the most useful of the techniques. Methods of monitoring and measuring the relative tooth movements are also described.

In this first of two articles the theory and practice of creating occlusal clearance for restorative procedures without the removal of tooth tissue is discussed. Earlier techniques for producing minor axial tooth movement are reviewed, together with the relevant literature on continuous eruption and occlusal stability. The indications for axial tooth movement and alternative treatment options are also considered.

Wear of the surface of the teeth is a natural consequence of ageing, but various conditions can render it pathological. In this article the authors describe two strategies for obtaining sensitive, personal information from patients who may be reluctant to disclose such details to a stranger.

Tooth wear seems to be an increasing problem, particularly amongst older patients who are retaining their teeth for longer. Having survived the ravages of caries and periodontal disease, they are then at risk of wearing out their dentition. Diagnosis and a full understanding of the aetiology is crucial to the effective management of unacceptable levels of tooth wear. Monitoring over a long period is helpful in planning life long management. There are specific treatment techniques which are useful in restoring badly worn teeth.

Society is becoming more litigious, and dentistry has not been exempt. However, by following correct and prudent professional procedures at all times, dentists may sensibly expect to avoid serious litigation. In the first of an irregular series on dento-legal topics, Bernard Smith reviews the thorny subject of negligence in dentistry, and gives advice on both how to prevent and how to respond to accusations. Other articles in the series will look at particular legal problems in the dental specialties.

The diagnosis of caries and treatment planning decisions have been reported to vary widely between individual dentists. However, opinions differ as to whether, in general, this results in too much or too little treatment. Eighty-six dentists, mainly attending post-graduate meetings, participated in this study. They were asked to make diagnostic and treatment planning decisions on a selection of extracted teeth set in realistic contact with each other. These decisions were compared with the appearance of the proximal surfaces before setting the teeth in contact, and the histological appearance of the teeth that were sectioned after the dentists had made their decisions. Opinions as to whether caries was present and whether it required treatment showed a wide distribution. However, had the decisions been acted upon, between 1-6% of the sound surfaces would have been filled, but 20-68% of teeth with clearly cavitated surfaces or histological evidence of dentine involvement would not have been filled.

The oil palm (Elaeis guineensis Jacq.) maintains a large leaf area throughout the year, but its productivity is limited by a low rate of dry matter production per unit leaf area. Stomatal closure, at times of low soil water availability and high atmospheric vapour pressure deficit, is an important factor limiting photosynthesis and hence dry matter production. In this paper, laboratory and field data are used to prepare a model of the relationships between net photosynthetic rate and stomatal conductance, and between stomatal conductance and environmental variables. Results show that high atmospheric vapour pressure deficits may limit production even in parts of the world where oil palms are not normally considered to suffer from water stress. The model can be used to design and evaluate irrigation systems, and to help quantify the potential value of oil palm genotypes with low stomatal sensitivity to either VPD or available soil water for use where irrigation is impractical.

The rise in phenylalanine ammonia-lyase (PAL) activity following excision of potato tuber discs is antagonized by increasing partial pressures of CO2 This inhibition is potentiated by depleting the atmospheric ethylene level. We suggest that the previously observed suppression of PAL appearance by in situ incubation of excised discs in reassembled tubers may be related to an internal atmosphere relatively rich in CO2 and of low ethylene content. The transition to an oscillatory time course of PAL activity that follows transfer of discs from in situ incubation to air appears to be accompanied by the development of enzyme activity becoming desensitized to repression by exogenous cinnamate. The concentration dependence of cinnamate uptake is not significantly altered by in situ pre-incubation of tuber discs.

The synthetic double-stranded polyribonucleotides, poly (rA):poly (rU) and poly (rI):poly (rC), were shown to be potent inhibitors of the in vitro plaque-forming cell (PFC) response to a thymus-dependent (SRBC) and thymus-independent (E. coli 0127 LPS) antigen in mouse C57BL/6 spleen cell cultures. The same polynucleotides had no effect on the PFC response of nude (athymic) mouse spleen cells to E. coli 0127 LPS, suggesting that functional T lymphocytes are necessary for the inhibitory effect. Enhancement effects were modest and inconsistent in the cultures. Poly (rA) and poly (rU) were ineffective as inhibitors. The data indirectly suggest that the inhibition may be due to the early production of interferon by functional T lymphocytes.

Potential academic ability, practical skill and personality characteristics should all be assessed in selecting dental students. Of these, practical skill commonly receives the least attention, largely because valid and reliable predictive tests are not available. The Spatial Relations Test, which might be used for this purpose, was administered to 1391 applicants to a dental school. There was little correlation between the results of the test and GCE 'A' level grades, showing that the test measured different abilities. However, there was a strong relationship between poor scores on the test and the number of students resigning from the course or failing to graduate on time.

Summary Measurements of the contact and embrasure areas of adjacent extracted teeth set in plaster blocks were made before groups of dentists undertook preparations on them. The prepared and adjacent teeth were examined and the findings related back to these measurements. Damage to the adjacent teeth was a common finding with both mesial–occlusal–distal (MOD) and complete crown preparations. There was some evidence that easier access to the contact area reduced the frequency of damage to teeth adjacent to MOD preparations. The taper of complete crown preparations did not conform to commonly recommended designs. This investigation highlights the need for greater consideration of approximal tooth surfaces when undertaking preparations and questions the practicality of achieving traditional features of complete crown preparation design. In teaching, greater emphasis should be placed on clinical reality rather than on theoretical, but unachievable ideals.

The effective coupling constants fρπγ fφπγ and fΩπγ are calculated from first principles by using single-variable dispersion representations. Baryon-antibaryon intermediate states are taken to dominate the calculation, and the reasons for this are discussed. We consider separately the special case in which vector mesons dominate the baryon electromagnetic form factors, and the general case, in which they do not. In the general case, meaningful equations can result only when the pion, alone, is taken off the mass shell, and then only if one subtraction is made at infinity. A convergence condition must be imposed on the integrand; the result is determined by this condition alone, and consequently depends only on the high-energy behaviour of the spectral function. In the special case, either the pion or the photon can be taken off the mass shell, both choices leading to the same result. On the assumption of vector dominance, this circumstance reconciles a result of Feldman and Matthews with a model of Gell-Mann, Sharp and Wagner. The results can be evaluated only provisionally, for lack of reliable input data on the strong interactions; such results as do emerge conform to experiment. The same methods are used to calculate the dependence of the π0 → γ e+ e- amplitude on the squared total mass of the Dalitz pair,i.e. of the virtual γ. In contrast to previous approaches, we find that in general a once-subtracted dispersion relation must be used; the subtraction constant must be supplied by an independent calculation of fπγγ in which only the pion leaves the mass shell. Our result (like previous ones) contradicts experiment as regards the magnitude of the dependence and, less unambiguously, as regards its sign; but, short of abandoning very basic theoretical ideas, there remains much less scope than formerly for reconciliation with experiment. A remeasurement is recommended.