A problem-based education program for patients with rheumatoid arthritis: evaluation after three and twelve months

OBJECTIVES: The aim of this work was to present a preliminary numerical analysis of the integration process of dental implants using a finite element simulation of the dynamic response following impulse excitation. Assessment of the osseointegration process has been previously examined using a numerical approach by calculating the natural frequency of a cantilever attached to the implant. The methodology adopted in this work allows a direct measurement of the implant response following impulse loading and avoids the addition of a bulky cantilever set-up. METHODS: The geometric configuration was obtained by averaging the coordinate data from tomographic scans of 14 mandibles. The materials properties were approximated from experimental analysis performed on trabecular and cortical bone tissue. A load was applied to the top of the implant in one direction resulting in an initial displacement. The implant was then freed and allowed to vibrate over approximately 10 cycles. Three fixity conditions were assumed by changing the properties of the surrounding bone ranging from full integration to a poorly integrated implant typical of the situation during bone healing following surgery. The results of the three fixity conditions were compared by calculating the fundamental displacement amplitudes and frequencies of the vibrating impact. RESULTS: The calculated results indicated that the implant vibrated at a predominant frequency when partially integrated with a displacement principally in the direction of the applied impulse. However, when the implant was fully integrated a more complex vibration pattern ensued, suggesting the superposition of two or more fundamentals. SIGNIFICANCE: Attention has been paid to the formulation of the numerical model for validation purposes as well as a reliable reference for the optimum interpretation of the experimental data. In this way it was possible to establish a simulation procedure to investigate the response of the tissues surrounding the implant and their properties at different stages of healing. It should be pointed out that the numerical procedures represented a valid preliminary approach to the problem and were capable of indicating a guide to the optimum design of the experimental apparatus for measurement of displacement and frequency in vivo.     

A compact time-of-flight spectrometer for electrofission studies

A compact time-of-flight spectrometer for measurements of fission fragment distributions is described. The start detector consists of a channel plate arrangement with an electrostatic mirror. The time resolution of PPACs, serving as stop detectors, has been optimized.Velocity distributions of ²⁵²Cf fragments and mean velocities are reported. The results are discussed with respect to planned (e, e'f) coincidence experiments at the Mainz microtron.     

Theory of porous electrodes—XII. The negative plate of the lead-acid battery

Partial differential equations describing the transport of mass and electricity in the pores of the negative electrode of a lead-acid battery were derived. The theory is based on exact transport equations and on the assumption that the electrode potential is governed by the Nernst equation. Volume changes in both phases are taken into account. Numerical solutions depend on the product of electrode thickness times current density and on the initial porosity. Differences between the negative and positive plates are discussed.     

Curing of epoxy resins with amines

Summary Using determination of the critical molar ratio of functional groups necessary for gel formation with amino groups in excess, network formation was investigated in the reaction of diglycidyl ether of Bisphenol A (DGEBA) and nitrogen-containing epoxy resins — diglycidylaniline and N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane with aromatic or aliphatic amines. It was found that in the case of nitrogen-containing epoxides the crosslinking is accompanied by pronounced cyclization, unlike in systems with DGEBA. Gelation depends on the relative reactivity of the primary and secondary hydrogen atom of the amino group. In the case of nitrogen-containing polyepoxides, the dependence of reactivities of adjacent glycidyl groups is also operative.     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process: Part I. Reactor design and scale down approach

For the continuous production of isopropanol-butanol mixtures by immobilised Clostridium spp. (the IBE process) two reactor types were studied: a fluidised bed reactor with liquid recycling (FBR) and an external loop gas lift reactor (GLR). A large scale design (50–65 m³) was made for both reactors. A regime analysis, by evaluating the time constants for e.g. mixing and conversion, identified the ruling regime. Via the scale down approach two representative model reactors were developed: a 10 dm³ FBR reactor (H/D=25, D=0.08 m) and a 15 dm³ external loop GLR (H/D = 12.5, D_r=D_d=0.08 m). For both reactors the hydrodynamical behaviour and the total reactor performance were studied and are described in parts II and III of this study.     

Molecular cytogenetics: applications in clinical genetics

Epidural neuroblastoma xenografts in nude rats causing paraparesis were treated with intravenous injection of an anti-GD2 monoclonal antibody 3F8. Metastatic or primary epidural tumors in humans cause rapid neurologic compromise. Treatment is often unsatisfactory. An animal model was established to study antibody targeted therapy of epidural tumor. Human neuroblastoma was xenotransplanted into the thoracic epidural space of nude rats. When paraparesis developed, animals were treated intravenously with an anti-GD2 monoclonal antibody, 3F8, either alone or radiolabeled with 131Iodine. Improvement in neurologic function occurred in 2 of 20 (10%) animals receiving no treatment or control antibody, 14 of 17 (82%) animals receiving 3F8 alone and all 9 animals receiving 131I-3F8 (p < 0.0001 for 3F8 or 131I-3F8 vs. control). Six animals treated with 3F8 alone recovered normal neurologic function and remained well until sacrifice 10 days later. Four animals treated with 3F8 alone had no tumor evident on pathologic examination. The percent injected dose of 131I-3F8/g tumor in 5 samples ranged from 0.73% to 3.8%. These observations demonstrate that neoplastic epidural compression of the spinal cord in the rat can be treated successfully with intravenous unmodified monoclonal antibody and that signs of neurologic dysfunction can be reversed. The potential of this approach in treating patients with epidural tumors and other neoplasms, especially those that are not sensitive to chemotherapy or radiotherapy, deserves to be explored.     

Matrix-assisted laser desorption/ionization mass spectrometry of proteins extracted directly from sodium dodecyl sulphate-polyacrylamide gels

A new strategy for the characterization of Coomassie Brilliant Blue stained SDS-PAGE separated proteins by UV-MALDI-MS is reported. The proteins are extracted directly from the polyacrylamide gel by treatment with an organic solvent mixture consisting of formic acid, acetonitrile, isopropanol and water in an ultrasonic bath. A fraction of the supernatant is then mixed directly with the matrix solution and measured by MALDI-MS. High quality spectra could be obtained from gels which were loaded with 6 pmol of myoglobin. Compared to other methods based on electroblotting or electroelution this method is much simpler and less time consuming. The sensitivity is higher than or comparable to the Coomassie Blue staining procedure for proteins up to about 25 kDa. Another advantage is that mass shifts due to charging effects of the membranes, which are common if membranes are mounted directly on the sample target, can be avoided. However, all proteins studied showed slightly higher masses than expected which reduces mass accuracy to 0.2-0.3%. This is presumably partly due to formylation of serine or threonine residues during incubation in formic acid. Gel electrophoresis induced modifications can contribute as well. The possibility of further characterizing the remaining part of the supernatant after extraction by means of proteolytic digestion is also demonstrated. The knowledge of both molecular weight of the whole protein and of the proteolytic fragments increases specificity for protein identification by searching in sequence databases.     

Controlling for a confounder monotonically related to exposure by means of isotonic quantile regression

We present a new approach to evaluating the effect of a continuous exposure factor when that factor increases with a covariate (for example, age) which is regarded as a potential confounder. The basic idea is to estimate, as functions of the covariate, some selected quantiles of the exposure distribution, under the assumption that the dependence of each quantile on the covariate is monotonic. The resulting estimates are then used to divide the data into different exposure categories. This method of categorizing the data implies that the covariate distribution will be almost the same in each exposure group. We illustrate the approach with a study of blood pressure and cardiovascular mortality.