Surgical planning for resection of an ameloblastoma and reconstruction of the mandible using a selective laser sintering 3D biomodel

Ameloblastoma is a benign locally aggressive infiltrative odontogenic lesion. It is characterized by slow growth and painless swelling. The treatment for ameloblastoma varies from curettage to en bloc resection, and the reported recurrence rates after treatment are high; the safety margin of resection is important to avoid recurrence. Advances in technology brought about great benefits in dentistry; a new generation of computed tomography scanners and 3-dimensional images enhance the surgical planning and management of maxillofacial tumors. The development of new prototyping systems provides accurate 3D biomodels on which surgery can be simulated, especially in cases of ameloblastoma, in which the safety margin is important for treatment success. A case of mandibular follicular ameloblastoma is reported where a 3D biomodel was used before and during surgery.

Post space cleaning using a new nickel titanium endodontic drill combined with different cleaning regimens

This study compared the effect of two drills and five cleaning regimens on post space debridement. One hundred extracted premolars were instrumented and obturated with warm vertical compaction of gutta percha. The teeth were divided into two groups according to the drill used to remove gutta percha/sealer and for post space preparation: a Largo drill (Largo; Dentsply, St Quentin en Yvelines, France) or a MTwo-PF drill (Sweden&Martina, Due Carrare, Padova, Italy). The following cleaning regimens were used: EDTA, ultrasonics, ultrasonics + EDTA, phosphoric acid, and distilled water. Scanning electron microscopic images of the post spaces were taken, and the presence of debris and of open dentin tubules were evaluated. The ultrasonics + EDTA, phosphoric acid, and EDTA groups were comparable in open tubules scores for both drills and in debris scores after the use of MTwo-PF (p > 0.05). The ultrasonics and control groups performed significantly worse (p < 0.05). The MTwo-PF drill resulted as effective as the Largo drill in obtaining a good post space cleaning, especially when followed by ultrasonics + EDTA irrigant regimen.

Influence of shaft design on the shaping ability of 3 nickel-titanium rotary systems by means of spiral computerized tomography

Objective. To evaluate the influence of shaft design on the shaping ability of 3 rotary nickel-titanium (NiTi) systems. Study design. Sixty curved mesial canals of mandibular molars were used. Specimens were scanned by spiral tomography before and after canal preparation using ProTaper, ProFile, and ProSystem GT rotary instruments. One-millimeter-thick slices were scanned from the apical end point to the pulp chamber. The cross-sectional images from the slices taken earlier and after canal preparation at the apical, coronal, and midroot levels were compared. Results. The mean working time was 137.22 +/- 5.15 s. Mean transportation, mean centering ratio, and percentage of area increase were 0.022 +/- 0.131 mm, 0.21 +/- 0.11, and 76.90 +/- 42.27%, respectively, with no statistical differences (P > .05). Conclusions. All instruments were able to shape curved mesial canals in mandibular molars to size 30 without significant errors. The differences in shaft designs seemed not to affect their shaping capabilities.

Considerations in the design of a mixed-method cluster evaluation of a community programme for 'at-risk' young people

This article discusses the design of a comprehensive evaluation of a community development programme for young people 'at-risk' of self-harming behaviour. It outlines considerations in the design of the evaluation and focuses on the complexities and difficulties associated with the evaluation of a community development programme. The challenge was to fulfil the needs of the funding body for a broad, outcome-focused evaluation while remaining close enough to the programme to accurately represent its activities and potential effects at a community level. Specifically, the strengths and limitations of a mixed-method evaluation plan are discussed with recommendations for future evaluation practice.

A new wavelet-based method for the solution of the population balance equation

A new wavelet-based method for solving population balance equations with simultaneous nucleation, growth and agglomeration is proposed, which uses wavelets to express the functions. The technique is very general, powerful and overcomes the crucial problems of numerical diffusion and stability that often characterize previous techniques in this area. It is also applicable to an arbitrary grid to control resolution and computational efficiency. The proposed technique has been tested for pure agglomeration, simultaneous nucleation and growth, and simultaneous growth and agglomeration. In all cases, the predicted and analytical particle size distributions are in excellent agreement. The presence of moving sharp fronts can be addressed without the prior investigation of the characteristics of the processes. (C) 2001 Published by Elsevier Science Ltd.

Skin-friction measurements in a supersonic combustor with crossflow fuel injection

Shock-tunnel experiments have been performed to measure the effect on skin-friction drag in a supersonic combustor of flow disturbances induced by hydrogen fuel injection transverse to the airstream. Constant-area, circular cross section combustors of lengths varying up to 0.52 m were employed. The experiments were done at a stagnation enthalpy of 7.2 MJ . kg(-1) and a Mach number of 4.3, with a boundary layer that was turbulent downstream of the 0.14-m station in the combustors. Combustor skin-friction drag was measured by a method based on the stress wave force balance, the method being validated by agreement between fuel-off skin-friction drag measurements and predictions using existing skin-friction theories. When fuel was injected, it was found that the drag remained at fuel-off values. Thus, the streamwise vortices and other flow disturbances induced by the fuel injection, mixing, and combustion, which are expected to be present in a scramjet combustor, did not influence the skin-friction drag of the combustors.

Ionic strontium fluorescence as a method for flow tagging velocimetry

A flow tagging technique based upon ionic fluorescence in strontium is investigated for applications to velocity measurements in gas flows. The method is based upon a combination of two laser based spectroscopic techniques, i.e. resonantly-enhanced ionisation and laser-induced ionic fluorescence. Strontium is first ionised and then planar laser-induced fluorescence is utilised to give 2D 'bright images' of the ionised region of the flow at a given time delay. The results show that this method can be used for velocity measurements. The velocities were measured in two types of air-acetylene flames - a slot burner and a circular burner yielding velocities of 5.1 +/- 0.1 m/s and 9.3 +/- 0.2 m/s, respectively. The feasibility of the method for the determination of velocities in faster flows than those investigated here is discussed.

Patient based method of assessing adverse events in clinical trials in rheumatology: the revised Stanford Toxicity Index

We describe the progress towards developing a patient rated toxicity index that meets all of the patient-important attributes defined by the OMERACT Drug Safety Working Party, These attributes are frequency, severity. importance to patient, importance to the clinician, impact on economics, impact on activities, and integration of adverse effects with benefits. The Stanford Toxicity Index (STI) has been revised to collect all attributes with the exception of impact on activities. However, since the STI is a part of the Health Assessment Questionnaire (HAQ). impact on activities is collected by the HAQ. In particular, a new question asks patients to rate overall satisfaction, taking into consideration both benefits and adverse effects. The nest step in the development of this tool is to ensure that the STI meets the OMERACT filter of truth, discrimination, and feasibility. Although truth and feasibility have been confirmed by comparisons within the ARAMIS database, discrimination needs to be assessed in clinical trials.

A novel method for solid-phase synthesis of oligosaccharides using the N-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) linker

The application of the N-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) linker for the solid-phase synthesis of oligosaccharides is described. The oligosaccharide products can be cleaved from the resin by hydrazine, ammonia or primary amines, but the linker is stable under the conditions of oligosaccharide synthesis. The first sugar can be attached to the resin linker via a vinylogous amide bond, or by ether linkage using a p-aminobenzyl alcohol converter. (C) 2001 Elsevier Science Ltd. All rights reserved.

Time-dependent master equation simulation of complex elementary reactions in combustion: Application to the reaction of (CH2)-C-1 with C2H2 from 300-2000 K

Computational simulations of the title reaction are presented, covering a temperature range from 300 to 2000 K. At lower temperatures we find that initial formation of the cyclopropene complex by addition of methylene to acetylene is irreversible, as is the stabilisation process via collisional energy transfer. Product branching between propargyl and the stable isomers is predicted at 300 K as a function of pressure for the first time. At intermediate temperatures (1200 K), complex temporal evolution involving multiple steady states begins to emerge. At high temperatures (2000 K) the timescale for subsequent unimolecular decay of thermalized intermediates begins to impinge on the timescale for reaction of methylene, such that the rate of formation of propargyl product does not admit a simple analysis in terms of a single time-independent rate constant until the methylene supply becomes depleted. Likewise, at the elevated temperatures the thermalized intermediates cannot be regarded as irreversible product channels. Our solution algorithm involves spectral propagation of a symmetrised version of the discretized master equation matrix, and is implemented in a high precision environment which makes hitherto unachievable low-temperature modelling a reality.

Lanczos subspace filter diagonalization: Homogeneous recursive filtering and a low-storage method for the calculation of matrix elements

We develop a new iterative filter diagonalization (FD) scheme based on Lanczos subspaces and demonstrate its application to the calculation of bound-state and resonance eigenvalues. The new scheme combines the Lanczos three-term vector recursion for the generation of a tridiagonal representation of the Hamiltonian with a three-term scalar recursion to generate filtered states within the Lanczos representation. Eigenstates in the energy windows of interest can then be obtained by solving a small generalized eigenvalue problem in the subspace spanned by the filtered states. The scalar filtering recursion is based on the homogeneous eigenvalue equation of the tridiagonal representation of the Hamiltonian, and is simpler and more efficient than our previous quasi-minimum-residual filter diagonalization (QMRFD) scheme (H. G. Yu and S. C. Smith, Chem. Phys. Lett., 1998, 283, 69), which was based on solving for the action of the Green operator via an inhomogeneous equation. A low-storage method for the construction of Hamiltonian and overlap matrix elements in the filtered-basis representation is devised, in which contributions to the matrix elements are computed simultaneously as the recursion proceeds, allowing coefficients of the filtered states to be discarded once their contribution has been evaluated. Application to the HO2 system shows that the new scheme is highly efficient and can generate eigenvalues with the same numerical accuracy as the basic Lanczos algorithm.

An extended interval dosing method for gentamicin in neonates

Traditional gentamicin dosing every 8–24 h depending on age and weight in neonates does not provide the ideal concentration–time profile to both optimize the concentration-dependent killing by aminoglycosides and minimize toxicity. Fifty-three neonates were audited prospectively while receiving gentamicin 2.5 mg/kg every 8–24 h, aiming for peak concentrations (Cmax) of 6–10 mg/L and trough concentrations (Cmin) 10 mg/L after the first dose. The mean area under the concentration versus time curve AUC0–24 was 93 mg•h/L (target = 100 mg•h/L). The extended interval dosing achieved higher Cmax values while ensuring that overall exposure per 24 h was acceptable. Prospective testing of the method demonstrated good predictive ability.

New nickel catalysts supported on highly porous alumina intercalated laponite for methane reforming with CO2

Alumina intercalated laponite (Al-laponite) was prepared with a polyethylene oxide (PEO) surfactant and used as supports of nickel catalysts for the carbon dioxide reforming reaction with methane to synthesis gas. The effects of the supports of intercalated laponite and catalyst preparation on catalytic activity, stability and carbon deposition were investigated for the above reforming reaction. We found that the pore structure of the Al-laponite supports can be tailored with the surfactant and the catalyst with well-developed porosity exhibited higher catalytic activity and a longer time of catalyst stability. (C) 2001 Elsevier Science B.V. All rights reserved.

The reliability of immunohistochemistry as a prescreening method for the diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC) - Results of an international collaborative study

Hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is an autosomal dominant condition accounting for 2–5% of all colorectal carcinomas as well as a small subset of endometrial, upper urinary tract and other gastrointestinal cancers. An assay to detect the underlying defect in HNPCC, inactivation of a DNA mismatch repair enzyme, would be useful in identifying HNPCC probands. Monoclonal antibodies against hMLH1 and hMSH2, two DNA mismatch repair proteins which account for most HNPCC cancers, are commercially available. This study sought to investigate the potential utility of these antibodies in determining the expression status of these proteins in paraffin-embedded formalin-fixed tissue and to identify key technical protocol components associated with successful staining. A set of 20 colorectal carcinoma cases of known hMLH1 and hMSH2 mutation and expression status underwent immunoperoxidase staining at multiple institutions, each of which used their own technical protocol. Staining for hMSH2 was successful in most laboratories while staining for hMLH1 proved problematic in multiple labs. However, a significant minority of laboratories demonstrated excellent results including high discriminatory power with both monoclonal antibodies. These laboratories appropriately identified hMLH1 or hMSH2 inactivation with high sensitivity and specificity. The key protocol point associated with successful staining was an antigen retrieval step involving heat treatment and either EDTA or citrate buffer. This study demonstrates the potential utility of immunohistochemistry in detecting HNPCC probands and identifies key technical components for successful staining.