Callus distraction for lengthening of mid-hand and finger stumps in congenital hand abnormalities--personal results and review of the literature

Distraction-lengthening technique is quite useful in a variety of congenital hand deformities with hypoplastic, or primary normal but secondary shortened (constriction ring syndrome) finger rays. It appears that around the age of two years is the earliest practical time to start distraction; certainly distraction and secondary surgical procedures to improve function should be completed before school entry age whenever possible. Between June 1990 and March 1993, nine distraction lengthening procedures (5 thumbs, 1 index, 3 little fingers) in five patients presenting with congenital hand deformities, were carried out. Although restoring length to the finger, lengthening does not provide normal circumference or, of course, interphalangeal joint motion. Amelioration in function seems to be more important than the esthetic gain. Distraction lengthening tolerates only few errors of indication, operative technique, and/or postoperative management. A high compliance of the patient and her/his parents as well as a close follow-up by an experienced surgeon, are mandatory for a good result. A variety of possible complications have been described. Generally, complication risk increases in cases of simultaneous and multiple level lengthening. Provided adequate operative technique and postoperative care, superficial pin infection and fracture in the region of distraction are the major complications. Contrary to adults, sufficient bone formation by distraction is the rule in children. Therefore, the distraction-lengthening technique is preferred to the distraction-interposition technique in the treatment of congenital hand deformities. The latter should only be used as a salvage procedure in the rare cases of insufficient callus formation. Because of the missing growth potential and reduced joint mobility, distraction lengthening is the therapy of second choice when compared to microvascular second toe transplantation.     

Korrosionsforschung in der Bundesanstalt für Materialprüfung (BAM) Berlin Überblick zum hundertsten Jubiläum ihrer Gründung

Corrosion research by Bundesanstalt für Materialprüfung (BAM) in Berlin A memorial review on the occasion of its 100th anniversary The report deals with the develop-ment in the field of corrosion, from the turn of the century to the present day. About 1900 scarcely anybody spoke of corrosion and corrosion protection. Start-ing from this zero point the whole field with its tremendous economic impor-tance has gone through an ever faster evolution. The knowledge concerning the origins of corrosion has been steadily increasing and well-founded. The corro-sion theories could be supported by practical experience and increasing scien-tific knowledge. On the strength of the knowledge on corrosion and the me-chanism of corrosion processes it became possible to develop efficient corrosion protection procedures. lnstitutions such as Materialprüfungsamt, Berlin-Dahlem, Chemisch-Technische Reichsanstalt and Bundesanstalt für Materialprüfung have had an important part in these succes-ses. It can be considered to be a parti-cular recognition of the achievements and merits of the predecessors of the present BAM, that after the merger of the two branches -i. e. materials test-ing and corrosion research -the latter bas been receiving particular attention and efficient support.     

Parameter pe′ der Elektronenteilleitfähigkeit in ZrO2(CaO)- und ThO2(Y2O3)-Festelektrolyten bei 1200 bis 1650 °C

Bestimmung des Parameters p_e′ (t_ion = 0,5) zur Kennzeichnung der Elektronenteilleitfähigkeit in festen Elektrolyten. Anwendung einer abgewandelten Polarisationsmethode mit EMK-Messung. Angabe der Parameter p_e′ für Festelektrolyte aus ZrO₂ mit einem Molenbruch x_CaO = 0,14 und aus ThO₂ mit einem Molenbruch bei Temperaturen zwischen 1200 und 1650 °C. Berechnung korrigierter Eichkurven für die elektrochemische Messung der Sauerstoffaktivitäten in Stahlschmelzen. Empfehlung einer bevorzugten Anwendung von ThO₂(Y₂O₃)-Elektrolyten zur Messung kleinster Sauerstoffaktivitäten.     

Simultaneous Detection of Positive and Negative Ions From Single Airborne Particles by Real-time Laser Mass Spectrometry

ABSTRACT

The instrumental setup used for simultaneous bipolar ion detection in on-line single-particle analysis by laser mass spectrometry is described. Particle size calibration has been performed using aerodynamic time-of-flight techniques. Mass spectra of several hundred ambient particles with aerodynamic diameters of 0.8 μm have been evaluated for statistical classification (Principal Components Analysis [PCA]) in order to identify main chemical components of the prominent particle classes.     

Computational comparison of two formulations for dynamic supply chain reconfiguration with capacity expansion and contraction

The strategic dynamic supply chain reconfiguration (DSCR) problem is to prescribe the location and capacity of each facility, select links used for transportation, and plan material flows through the supply chain, including production, inventory, backorder, and outsourcing levels. The objective is to minimize total cost. The network must be dynamically reconfigured (i.e., by opening facilities, expanding and/or contracting their capacities, and closing facilities) over time to accommodate changing trends in demand and/or costs. The problem involves a multi-period, multi-product, multi-echelon supply chain. Research objectives of this paper are a traditional formulation and a network-based model of the DSCR problem; tests to promote intuitive interpretation of our models; tests to identify computational characteristics of each model to determine if one offers superior solvability; and tests to identify sensitivity of run time relative to primary parameters.     

ON MACHINE VISION AND CAST

Building machines that “see” is a complex systems engineering task. While, at present, universal vision machines (with performance comparable to the human visual system) appear to be impractical, special purpose machines have been devised successfully to operate in restricted application domains. Designing such a dedicated system usually requires detailed knowledge of the application domain, experience with available processing techniques, and a large experimentation effort. Despite the peculiarities of different vision domains, many of them share similar processing techniques. We propose to develop computerized tools to support the development of application-specific vision systems in order to make this process less time-consuming and costly. We discuss some of the fundamental problems of machine vision and examine why current computer-aided systems theory (CAST) technology is not sufficient for this task. On the other hand it seems likely that developments in the Held of machine vision could have a significant impact upon other CAST applications of similar complexity.     

Application of a Spectral Element Method to Two-Dimensional Forward-Facing Step Flow

In the present study, we investigate the two-dimensional laminar flow through a one-sided constriction of a plane channel with a ratio of h:H=1:4 (where h is the step height and H is the channel height). The computational approach employed is based on a mixed implicit/explicit time discretization scheme together with a highly accurate spatial discretization using a P _N –P _N–2 spectral-element method. It is well known that this so-called forward-facing step (FFS) flow exhibits a singularity in the pressure and the velocity derivatives at the corner point. We account for this singularity by a geometric mesh refinement strategy that was proposed in a hp-FEM context. A detailed numerical study of the FFS flow reveals that length and height of the recirculation zone in front of the step are almost constant for creeping flow. In the limit of high Reynolds numbers the length and height of the recirculation zone increase proportional to Re ^0.6 and Re ^0.2, respectively.     

Zur Eulerschen Knickung

Ohne Zusammenfassung ProfessorWilhelm Heitland, Fachhochschule Bielefeld FBR 3 (Maschinenbau). Lehrgebiet Mathematik.     

Ubiquitous computing and interaction

A short overview of the emerging field ubiquitous computing is given. It is argued, that this technology, characterized as highly distributed and interactive, requires a shift of focus from the traditional view of computer science as a domain of computable functions and turing machines (TM) to a cybernetic view of energy–signal–control cycles. This is accompanied by a reconsideration of interface-technology and the derivation of a new type of locally controlled signal to energy transformation based on the continuity of energy flow. It is shown how the concept of hyper-bonds could serve some requirements in this new field. Some applications in mixed reality and mechatronics are given and further perspectives for human–machine collaboration, human skills, and knowledge are presented.