Practical prototyping

The design of robotic mechanisms is a complex process involving geometric, kinematic, dynamic, tolerance, and stress analyses. In the design of a real system, the construction of a physical prototype is often considered. Indeed, a physical prototype helps the designer to identify the fundamental characteristics and the potential pitfalls of the proposed architecture. However, the design and fabrication of a prototype using traditional techniques is rather long, tedious, and costly. In this context, the availability of rapid prototyping machines can be exploited in order to allow designers of robotic mechanisms to build prototypes rapidly and at a low cost. In the article, the rapid prototyping of mechanisms using a commercially available computer-aided design (CAD) package and a fused deposition modeling (FDM) rapid prototyping machine is presented. A database of lower kinematic pairs (joints) is developed using the CAD package, and parameters of fabrication are determined experimentally for each of the joints. These joints are then used in the design of the prototypes where the links are developed and adapted to the particular geometries of the mechanisms to be built. Also, a procedure is developed to build gears and Geneva mechanisms. Examples of mechanisms are then studied and their design is presented. For each mechanism, the joints are described and the design of the links is discussed. Some of the physical prototypes built using the FDM rapid prototyping machine are shown     

Self-administered preventive programme for sedentary workers: reducing musculoskeletal symptoms or increasing awareness?

The objective of this study was to evaluate an auto-instructional preventive programme designed to allow the subjects to identify critical aspects related to their work and musculoskeletal comfort, and provide them with some simple alternatives for controlling the identified problems. The programme was evaluated by 36 secretaries and bank clerks through their symptom perception before and after the programme. The results showed that the symptoms increased in number and severity. The programme seemed to have helped the participants to become aware of the ergonomic problems present in their job and to link these problems to physical symptoms. Self-administered preventive programmes can lead to clearly negative results when applied as the only measure to control musculoskeletal symptoms.     

Strain-dependent recovery of spontaneous hindlimb movement in spinal cord transected mice (CD1, C57BL/6, BALB/c).

Reorganization and plasticity after spinal cord injury have been recently shown to take place in sublesional neuronal networks, but the possibility of strain-dependent changes at that level has never been explored. The authors studied the spontaneous return of hindlimb movement in low-thoracic spinal cord transected (Tx) mice from 3 commonly used strains. Without intervention, most CD1, C57BL/6, and BALB/c mice displayed some hindlimb movement recovery after Tx. Although all assessment methods unanimously reported that CD1 displayed higher recovery levels than did the C57BL/6 and BALB/c, higher scores were generally found with the Antri-Orsal-Barthe (M. Antri, D. Orsal, & J. Y. Barthe, 2002) and the Average Combined Score (P. A. Guertin, 2005a) methods. Such spontaneous recovery in low-thoracic Tx mice is likely the result of neuronal plasticity at the lumbosacral spinal cord level, suggesting that these sublesional changes are strain dependent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pre-partitioning as a means of enhancing pairwise interchange solutions to quadratic assignment problems

Two partition/interchange processes are described for solving quadratic assignment problems. Explicit partitioning is used in both methods to decompose the initial large graph into several smaller graphs for initial placement and subsequent interchange optimization. Comparative runs were made between the two processes and against the interchange process without partitioning on problems involving up to 100 vertices. The comparative results clearly establish the effectiveness of partitioning in enhancing the performance of interchange processes and provide a basis for selecting partitioning processes.While the two methods described herein were developed for microcircuit placement problems, they are applicable to quadratic assignment problems arising from numerous other settings.     

Cantilever-based optical deflection assay for discrimination of DNA single-nucleotide mismatches

Characterization of single-nucleotide polymorphisms is a major focus of current genomics research. We demonstrate the discrimination of DNA mismatches using an elegantly simple microcantilever-based optical deflection assay, without the need for external labeling. Gold-coated silicon AFM cantilevers were functionalized with thiolated 20- or 25-mer probe DNA oligonucleotides and exposed to target oligonucleotides of varying sequence in static and flow conditions. Hybridization of 10-mer complementary target oligonucleotides resulted in net positive deflection, while hybridization with targets containing one or two internal mismatches resulted in net negative deflection. Mismatched targets produced a stable and measurable signal when only a four-base pair stretch was complementary to the probe sequence. This technique is readily adaptable to a high-throughput array format and provides a distinct positive/negative signal for easy interpretation of oligonucleotide hybridization.     

Determination of spatial and temporal characteristics as an aid to neural network cloud classification

Previous studies of cloud classification from meteorological satellite imagery have shown that artificial neural networks (ANNs) perform as well as, or better than, statistical pattern recognition when multispectral features, supplemented with selected textural features, are used. These features, however, represent only a subset of the full range of features available in this imagery. Spatial characteristics based on the shape of clouds, and temporal characteristics, derived from image sequences, can be more direct pointers to cloud type. In this paper the methods for the determination of such parameters are described, some results are presented, and the effectiveness of the methods are discussed.     

Occupational posture exposure among construction electricians

The aim of this study is to record, objectively describe and compare working postures of Brazilian and Norwegian construction electricians. Postures of the upper arms, head, and neck during work and breaks were quantified by means of inclinometry for a representative sample of 12 Brazilian and 12 Norwegian electricians in the construction industry during a full work-shift. Despite that differences were found between specific work-related factors, Brazilian and Norwegian workers revealed a high and very similar level and pattern of postures for all evaluated body regions, suggesting that results could be extrapolated to other electricians. Upper arm elevation was high and similar for both groups and head flexion and extension was pronounced compared to other occupations. Thus, extreme postures were identified for construction electricians in both countries, with similar exposure pattern also for defined tasks (planning, support and wiredraw), suggesting that this job is risky regardless organizational differences.     

Developing an inpatient practicum program for patients with serious and persistent mental illness.

Training psychology students to treat patients with serious and persistent mental illness (SPMI) can provide an excellent opportunity for psychologists to help an historically disenfranchised and ignored population. With proper training, psychologists can play an important role in the development, provision, and administration of services to people with SPMI. We outline some of the issues to be considered in developing such a training program for practicum students, discuss the clinical skills and systemic issues that need to be mastered at the graduate level, and delineate the process by which this can be achieved in an inpatient, acute-care setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

KINETICS MODEL FOR INTERFACIAL REACTION OF COPPER EXTRACTION WITH 1-(2'-HYDROXY-5'-NONYLPHENYL)-l-ETHANONE (E)-OXIME AND 1-(2'-HYDROXY-5'-METHYLPHENYL)-1-DECANONE (E)-OXIME

Abstract

A kinetic model for the interfacial reaction of copper extraction with Individual 1-(2'-hydroxy-5'-nonylphenyl)-1-ethanone (E)-oxime and 1-(2'-hydroxy-5'-methylphenyl)-1-decanone (E)-oxime having the same hydrophobicity was used to interpret the effect of hydroxyoxime partition and interfacial activity upon the rate of copper extraction from acidic sulfate solutions. Due to similar hydrophobicity of studied extractants the proposed model, which is very sensitive to the errors of the partition coefficient determination, cannot support any version of extraction mechanism.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.