Evaluation of handgrip force from EMG measurements

A series of experiments were performed in order to investigate whether estimates of handgrip force could be derived with fair accuracy from surface EMG levels recorded on the finger flexors of the forearm, taking into account the position of the wrist in the flexion-extension plane and in the ulnar-radial deviation plane. Handgrip forces (on a JAMAR dynamometer) and corresponding surface EMG levels (on the finger flexors of the forearm) were recorded for 20 subjects in 11 postures of the wrist and for 30% and 70% of the MVC in neutral posture. A mathematical empirical model was developed using multiple non-linear regression analysis. Although quite simple, it provides very reliable results, the correlation coefficient between predicted and observed forces being 0.895. Its use must, however, be restricted to work situations where: (a) the hand efforts are of the same type and involve the same muscles as those exerted on the dynamometer; (b) the hand is in neutral pro-supination; and (c) no voluntary effort is exerted by the wrist flexors except for maintaining the wrist posture.     

Integration of collaboration and interaction analysis mechanisms in a concern-based architecture for groupware systems

Collaboration and interaction analysis allows for the characterization and study of the collaborative work performed by the users of a groupware system. The results of the analyzed processes allow problems in users’ collaborative work and shortcomings in the functionalities of the groupware system to be identified. Therefore, automating collaboration and interaction analysis enables users’ work to be assessed and groupware system support and behavior to be improved. This article proposes a concern-based architecture to be used by groupware developers as a guide to the integration of analysis subsystems into groupware systems. This architecture was followed to design the COLLECE groupware system, which supports collaborative programming practices and integrates an analysis subsystem that assesses different aspects of the work carried out by the programmers and adapts the functionality of the system under specific conditions.     

Novel fatty acid esters of (7E, 12E, 18R, 20Z)-variabilin from the marine sponge Ircinia felix

The methanolic extract of the marine sponge Ircinia felix has yielded nine novel fatty acid esters, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-22-methyltricosadienoate, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-tetracosadienoate, (7E, 12E, 18R, 20Z)-variabilin hexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 10-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 15-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 14-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 9-octadecenoate, (7E, 12E, 18R, 20Z)-variabilin octadecanoate, and (7E, 12E, 18R, 20Z)-variabilin 2,11-dimethyloctadecanoate, along with the recently described (7E, 12E, 18R, 20Z)-variabilin 11-methyloctadecanoate. The characterization of the new fatty acids (5Z, 9Z)-22-methyltricosadienoic and 2,11-dimethyloctadecanoic acids is also described. The chemical structures were determined by extensive spectroscopic, chromatographic, and chemical analyses.     

The effect of magnetic field on the impurity binding energy of shallow donor impurities in a Ga1?xInxNyAs1?y/GaAs quantum well

Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga_1−xIn_xN_yAs_1−y/GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations.     

MHP‐OSGi convergence: a new model for open residential gateways

Nowadays, we are living in a time of important technological changes that affect our lives at home and our communication with the outside world. Among them, the developments in Interactive Digital TV (IDTV) and the smart home field can be considered as particularly important. Related to the former, the new Set‐Top Boxes (STBs) are not only a decoder for digital television broadcast but also an entry point to the Information Society and a suitable platform to support the execution of interactive applications. With regards to the latter, the Residential Gateways (RGs) combine different network technologies to allow the connection of different electronics devices and appliances at home, not only with each other but also with the Internet. Since there is no widespread consensus about the configurations and functions of the RGs, we propose to coordinate the two aforementioned worlds by extending the functionality of STBs to become a RG. Our proposal consists of merging the Multimedia Home Platform (MHP), one of the main standard frameworks for IDTV, with Open Service Gateway Initiative (OSGi), the most widely used open platform to set up RGs. To overcome the radically different nature of these specifications—the function‐oriented MHP middleware and the service‐oriented OSGi framework—we define a new kind of application, coined as XbundLET. This application is able to bridge the gap between the two frameworks and make their interaction feasible. We also show how this proposal has the potential to enable the production of scenarios that cannot currently be put into practice in a natural way. Copyright © 2006 John Wiley & Sons, Ltd.     

Pseudopterosin Content Variability of the Purple Sea Whip Pseudopterogorgia elisabethae at the Islands of San Andres and Providencia (Sw Caribbean)

To determine pseudopterosin composition and concentration in colonies of Pseudopterogorgia elisabethae from the islands of San Andres and Providencia, we collected fragments of individual colonies at various sites and depth ranges around the islands. Chromatographic profiles of the polar fraction, particularly those obtained by HPLC-MS analyses, allowed us to recognize two different chemotypes. Chemotype 1 characterized samples from Providencia whereas chemotype 2 characterized samples from San Andres. A complex pseudopterosin mixture (compounds 1-13) characterized chemotype 1. These compounds were isolated by a combination of chromatographic methods and identified by spectroscopic methods (MS, UV, 1H, and 13C NMR). We identified the known pseudopterosins G and K and seco-pseudopterosin A. We also isolated and identified seven new compounds, pseudopterosins P-V, isomers of known pseudopterosins. Pseudopterosins G and K were found at concentrations ranging between 1 and 3% of the animal dry mass. Pseudopterosins Q and U were the major compounds reaching up to 6% of the animal dry mass at some locations. Major metabolites in chemotype 2 had a molecular weight and fragmentation pattern different from that observed in the pseudopterosins, as determined by HPLC-MS. Total pseudopterosin concentration in this chemotype was below 3% dry mass at all sites. Total pseudopterosin concentration was significantly higher in chemotype 1, with concentrations ranging between 4 and 20% dry mass. At most locations on Providencia, however, total pseudopterosin concentration ranged between 11 and 15% dry mass. Concentrations exceed reports from other locations in the Caribbean. Furthermore, pseudopterosin composition in our samples is quite different from those in specimens of P. elisabethae from the Bahamas and Bermuda. Pseudopterosins G, K, and P-V are characteristic of P. elisabethae colonies from the island of Providencia, while pseudopterosins A-D are characteristic of colonies of P. elisabethae from the Bahamas islands, and pseudopterosins E-L have been isolated from P. elisabethae from the Bahamas and Bermuda. The overall morphology of P. elisabethae can be variable, and chemical differences are not correlated to specific morphs. We confirmed the species identity of each colony by morphological and sclerite analysis and found no significant differences in sclerite dimensions among different colonies and chemotypes.