A Randomised Controlled Trial of a Universal Bonding Agent at Three Years: Self Etch vs Total Etch.

General dental practice is increasingly being recognised as the ideal situation for the conduct of clinical trials into the longevity of restorations. The aim of this study was to investigate the survival of 64 nanofilled resin composite (Filtek Supreme XTE) restorations placed principally in loadbearing cavities using a Universal dentine bonding agent (Scotchbond Universal), in five UK dental practices by members of the UK-based practice-based research group, the PREP Panel. A split mouth design was used, comprising patients who required two restorations, with one of the restorations receiving a total etch approach using phosphoric acid and the other being placed using a self-etch approach. The results indicated good performance of the restorations examined, with no difference, in terms of marginal characteristics, between the restorations which received total etching and those which did not.

Two year clinical evaluation of a low-shrink resin composite material in UK general dental practices.

OBJECTIVE: A novel resin composite system, Filtek Silorane (3M ESPE) with reduced polymerization shrinkage has recently been introduced. The resin contains an oxygen-containing ring molecule ('oxirane') and cures via a cationic ring-opening reaction rather than a linear chain reaction associated with conventional methacrylates and results in a volumetric shrinkage of ∼1%. The purpose of this study was to review the literature on a recently introduced resin composite material, Filtek Silorane, and evaluate the clinical outcome of restorations formed in this material. METHODS: Filtek Silorane restorations were placed where indicated in loadbearing situations in the posterior teeth of patients attending five UK dental practices. These were evaluated, after two years, using modified USPHS criteria. RESULTS: A total of 100 restorations, of mean age 25.7 months, in 64 patients, were examined, comprised of 30 Class I and 70 Class II. All restorations were found to be present and intact, there was no secondary caries. Ninety-seven per cent of the restorations were rated optimal for anatomic form, 84% were rated optimal for marginal integrity, 77% were rated optimal for marginal discoloration, 99% were rated optimal for color match, and 93%% of the restorations were rated optimal for surface quality. No restoration was awarded a "fail" grade. No staining of the restoration surfaces was recorded and no patients complained of post-operative sensitivity. SIGNIFICANCE: It is concluded that, within the limitations of the study, the two year assessment of 100 restorations placed in Filtek Silorane has indicated satisfactory clinical performance.

The current status of materials for posterior composite restorations: the advent of low shrink.

UNLABELLED: Polymerization contraction, and the stresses associated with this, have presented problems with resin composite materials, particularly when used to restore cavities in posterior teeth. This paper summarizes the problems associated with polymerization contraction and examines methods used to overcome this, in particular, by the use of materials which have reduced percentage contraction when compared with traditional materials. CLINICAL RELEVANCE: Use of a material with reduced polymerization contraction should lead to simpler restoration placement.

Application of process-based models to forest management: experience with PROMOD, a simple plantation productivity model.

Process-based growth models are rarely used as a basis for decisions in forest management. Reasons for this are discussed and the development and application of PROMOD, a simple process-based plantation productivity model designed to meet the needs of managers, is described. In particular,PROMOD is intended for screening prospective plantation sites on the basis of readily available input data, including site latitude, soil characteristics, and long-term climate data. Originally developed for use with Eucalyptus globulus Labill., PROMOD has since been parameterized also for Eucalyptus nitens (Deane & Maiden) Maiden and Pinus radiata D. Don. We discuss the adaptation of PROMOD to new environmental conditions and species; the sensitivity of the model's predictions to changes in model structure, the values of its physiological parameters and the accuracy and resolution of site survey information; and the use of the model both in assessing the profitability of plantation irrigation in semi-arid regions, and for generating broad-area productivity maps.

A wide-angle gradient index optical model of the crystalline lens and eye of the octopus.

Cephalopods and fish have had no common ancestor since the Cambrian, and their eyes are a classic example of convergent evolution. The octopus has no cornea, and immerson renders the trout cornea optically ineffective. As a result, the nearly spherical lens is responsible for all refraction in these eyes. In spite of the fact that the octopus lens consists of two joined parts, while the trout lens consists of one part, we show here that their optical properties are very similar. An index gradient bends rays within these lenses, adding power and correcting spherical aberration. High spherical symmetry in both lenses strongly reduces other monochromatic aberrations and yields a wide field of vision, advantageous in attack and evasion. The octopus Mattheissen's ratio, 2.83, an inverse measure of light-gathering power, lies above the trout value of 2.38 but within the range of values reported for fish. Strong uncorrected longitudinal chromatic aberration is nearly identical in both animals as a result of similar lens protein optical properties, and will limit resolution. We discuss how animal lifestyle requirements and lens material properties influence the design of these eyes.

Modeling the effect of physiological responses to green pruning on net biomass production of Eucalyptus nitens.

Green pruning of Eucalyptus nitens (Deane and Maiden) Maiden increases instantaneous rates of light-saturated CO(2) assimilation (A), and changes patterns of total leaf area and foliage distribution. We investigated the importance of such changes on the rate of recovery of growth following pruning. A simple process-based model was developed to estimate daily net biomass production (G(d)) of three-year-old plantation-grown trees over a 20-month period. The trees had been pruned by removal of 0, 50 or 70% of the length of green crown, equivalent to removal of 0, 55 or 88% of leaf area, respectively, when the plantation verged on canopy closure. Total G(d) was reduced by only 20% immediately following the 50%-pruning treatment, as a result of both the high leaf dark respiration and low A in the portion of the crown removed compared to the top of the crown. Pruning at the time of canopy closure preempted a natural and rapid decline in G(d) of the lower crown. Although leaf area index (L) was approximately 6.0 at the time of pruning, high light interception (95%) occurred with an L of 4.0. The 50%-pruning treatment reduced L to 3.5, but the physiological responses to pruning were sufficient to compensate fully for the reduction in intercepted radiation within 110 days of pruning. The 70%-pruning treatment reduced L to 1.9, and reduced G(d) by 77%, reflecting the removal of branches with high A in the mid and upper crown. Physiological responses to the 70%-pruning treatment were insufficient to increase G(d) to the value of unpruned trees during the study. Model sensitivity analysis showed that increases in A following pruning increased G(d) by 20 and 25% in the 50- and 70%-pruned trees, respectively, 20 months after pruning. Changes in leaf area/foliage distribution had a greater effect on G(d) of 50%-pruned trees (47% increase) than did changes in A. However, the reduction in photosynthetic potential associated with the 70%-pruning treatment resulted in only small changes in leaf area/foliage distribution, which consequently had little effect on G(d). The effects of physiological processes occurring within the crown and in response to green pruning on G(d) are discussed with respect to pruning of plantations.

Freezing behaviors in leaf buds of cold-hardy conifers visualized by NMR microscopy.

A calibration curve was established to convert plant area index of Eucalyptus nitens (Deane and Maiden) Maiden, assessed with a Li-Cor LAI-2000, to leaf area index, LAI. Based on a comparison of this calibration curve with existing calibration curves for other species, we concluded that a generic calibration curve may be applicable for the assessment of LAI in eucalypt plantations. The Li-Cor LAI-2000 measurements were used to correlate the equilibrium LAI of E. nitens plantations with mean annual temperature. These and other data were then combined to develop relationships between LAI in both E. nitens and E. globulus Labill. plantations and mean annual temperature and water stress. In plantations of both species, LAI declined linearly with water stress. However, marked differences in the effect of suboptimal growth temperatures on LAI were observed between species: on cold sites, LAI of E. nitens was markedly higher than LAI of E. globulus. A simple analytic model of net primary production (NPP) was developed. In this model, increasing LAI increased light interception and hence dry matter production, but simultaneously increased canopy respiration. Consequently, for a given light utilization coefficient (epsilon), there was a value of LAI that maximized NPP. The model was parameterized for E. globulus and used to investigate the influences of water stress and mean annual temperature on LAI through their effects on epsilon. The model indicated that the value of LAI that was predicted to maximize NPP under various water and temperature stress regimes was similar to the value of LAI observed in the field under similar conditions only if leaf longevity was linked to water and temperature stress.

A wide-angle gradient index optical model of the crystalline lens and eye of the rainbow trout.

Trout lens external shape and internal refractive index gradient structure were measured and used to construct an optical lens model that predicts by ray tracing the average longitudinal spherical and chromatic aberration, focal length and image quality. The nearly spherical shape of the lens was measured from photographs, and the internal refractive gradient structure was measured directly with a special Pulfrich areal refractometer. Longitudinal spherical aberration and back focal length were measured using a simplified Hartmann test using laser beams and a Schlieren test which additionally made refractive index gradient fine structure visible and detected scattering, axial symmetry and structural irregularity. Axial focus shift caused by longitudinal chromatic aberration was measured using a star test. The model lens was then incorporated into a model trout eye based on vertical and horizontal eye frozen sections. Calculated model function yields insight into the relation between eye and lens structure and optical behaviour. Semi-random secondary structural features act as perturbations on the basic model, and will result in point image fine structure.

Organizing for drug-usage evaluation.

Because QA is the chief interest of the Joint Commission, hospital pharmacists must strive to have a well-organized DUE plan and process. However, merely satisfying a Joint Commission surveyor is not a good enough reason to invest in the DUE process. DUE is deceptively complex and labor intensive for hospital and medical staff alike. A better reason to plunge into DUE is to enable pharmacists to concurrently monitor pharmacotherapy, to intervene on behalf of patients, and to positively affect patients' therapeutic outcomes. Thereby, DUE really fits pharmacy's responsibility for pharmaceutical care.

Refractive index within the lens of a goldfish eye determined from the paths of thin laser beams.

The paths of 15 micron diameter laser beams traversing goldfish eye lenses were photographed. Measurements of these photographs gave experimental data for the distance of the exit point of each ray from the lens axis as a function of the corresponding entrance distance. A number of mathematical models with distinct distributions of refractive index within the lens were analysed by tracing rays to simulate the experimental data. The only distributions for which the simulated and experimental data were in agreement have a refractive index N which varies continuously with distance r from the lens center in a manner consistent with that originally proposed by Matthiessen: N2 = a - br2. Estimates for the central (1.55-1.57) and surface (1.35-1.38) refractive indices of the goldfish eye lens are derived from the preferred model, but these differ from those previously given by Matthiessen for other species. The optical performance of the lens models is also compared by third-order analyses.

A comparative analysis of the development of the primary somatosensory cortex: interspecies similarities during barrel and laminar development.

The development of the barrels and layers II-V was examined in Nissl-stained preparations of the primary somatosensory cortex in six species--hamster, mouse, rat, gerbil, rabbit, and guinea pig--that have increasingly longer gestation periods. The barrels and layers II-V begin to differentiate postnatally during the first week postpartum in the hamster, mouse, rat and gerbil; perinatally in the rabbit; and approximately 4 weeks prenatally in the guinea pig. The structure of the barrels and layers II-V is similar at the onset of their differentiation in each species, even though there are interspecies differences in the mature structure of the barrels and layer V. The rate of the initial differentiation of the barrels and layers II-V is also similar in each species, even though there are considerable interspecies differences in the duration of the preceding period of development. In each species, layer V begins to differentiate first from the cortical plate and, within 1 or 2 days, contains sublayers that eventually disappear in the rabbit and guinea pig. About 3 days after the initial differentiation of layer V, layers II-IV begin to differentiate, seemingly simultaneously, causing the cortical plate to have a trilaminar appearance. Barrels are first evident just before the appearance of the trilaminar plate in hamsters; concomitant with the trilaminar plate in mice, rats, and guinea pigs; and just after the trilaminar plate in gerbils and rabbits. Septa appear 1 or 2 days after the barrels except in rabbits, which never have septa. Barrel maturation proceeds rapidly after the initial appearance in all species except the hamster, in which continued maturation seems to be delayed until the appearance of the trilaminar plate. The barrels in immature rats and rabbits become more prominent than they will eventually be in the adults. Our results indicate a close and rapid developmental affiliation between layers II-V, especially layers II-IV, that seems quite separate from the development of layers I and VI. However, barrel development and differentiation of layers II-IV seem to be closely, but independently initiated. Secondary remodeling occurs in layer V and the barrels of some species.

Classification scheme and nomenclature for refractive-index distributions.

A classification scheme and nomenclature for inhomogeneous refractive-index distributions is proposed which is consistent, unambiguous, and appeals to intuition. The classification is based on (1) the generic shape of the isoindicial surfaces, (2) the detailed dependence of the index on some position coordinate characterizing the isoindicial surfaces, and (3) whether the index distribution is given by N or N2 as some function of position. The scheme is illustrated by distributions which are of technological or physiological interest.

Augmentation of postischemic brain damage by severe intermittent hypertension.

The neurological recovery and histological changes were studied in monkeys after intermittent postischemic arterial hypertension after 16 min of global brain ischemia. Ischemia was produced with a high pressure (1500 mm Hg) neck tourniquet and systemic arterial hypotension. Intensive care and life support, including monitoring of physiological variables, were provided for 7 days. Postischemia all monkeys were immobilized; ventilation was controlled and mean arterial pressure was maintained between 85--115 mm Hg for the first 48 hours. Immediately postischemia in four monkeys, intermittent arterial hypertension (i.e., 150--190 mm Hg) was induced by norepinephrine infusion for 3--5 min. Hypertensive episodes were repeated at 15, 30, 60, and 120 min postischemia, once every hour for the first 24 hours and once every 2 hours between 24 and 48 hours. Thereafter, the monkeys were allowed to breathe spontaneously. Four control monkeys were similarly treated except that arterial hypertension was not induced. Neurological recovery was evaluated by EEG, intracranial pressure, neurological deficit scoring, and histological examination of the brain after killing on day 7 postischemia. The neurological deficit score (100 % = brain death; 50% = vegetative state; 0% = normal) in control monkeys on day 7 was 17.8 +/- 1.8 (SEM) % compared to 46.3 +/- 6.5% (p less than 0.05) in the hypertension group. EEG recovery was delayed and the postischemic increase in intracranial pressure was prolonged in the hypertension group. Histological damage scores in the brain correlated with neurological deficit scores. Severe intermittent hypertension has a deleterious effect on neurological recovery after global brain ischemia.

[Experimental study of barbiturate application following anoxic encephalopathy]. / Etude expérimentale de l'utilisation des barbiturates après l'encéphalopathie anoxique.

The protective effect of thiopental on neurological lesions provoked by cerebral anoxie was studied in the monkey. Cerebral ischemia was induced by a cervical tourniquet applied for a period of 16 minutes. A control series of 10 animals received only the normal resuscitation. A series of 27 monkeys received either 90 mg/kg of thiopental at 5, 10, 15, 30 or 60 minutes following ischemia, or 120 mg/kg at the 30th or 60th minute. One third of the dose was administered within 5 minutes and the rest during the following 55 minutes. The results shows that the prevention, by thiopental, of the clinical and histological lesion secondary to cerebral anoxia is effective when this drug is administered before the 15th minute. With 90 mg/kg administered at the 30th or 60th minute the improvement was slight: with 120 mg/kg it was greater if the injection was given at the 60th rather than at the 30th minute. These results, along with the mechanisms which may explain the action of thiopental, are discussed.

Evaluation of insecticide smears for the control of screw-worm fly, Chrysomya bezziana, in Papua New Guinea.

Three new insecticide smear preparations for the control of Chrysomya bezziana larvae infesting wounds of cattle have been tested under field and laboratory conditions and compared with an established preparation EQ 335 which is based on 3% lindane. Two preparations based on 3% coumaphos proved comparable to EQ 335 in the field trials and exhibited more prolonged residual effectiveness in laboratory tests. A smear preparation based on 2.5% methoxychlor was only effective in controlling 1 and 2 day-old larvae in wounds and was generally inferior to other smears tested in the laboratory.