SSL: A Theory of How People Learn to Select Strategies.

The assumption that people possess a repertoire of strategies to solve the inference problems they face has been raised repeatedly. However, a computational model specifying how people select strategies from their repertoire is still lacking. The proposed strategy selection learning (SSL) theory predicts a strategy selection process on the basis of reinforcement learning. The theory assumes that individuals develop subjective expectations for the strategies they have and select strategies proportional to their expectations, which are then updated on the basis of subsequent experience. The learning assumption was supported in 4 experimental studies. Participants substantially improved their inferences through feedback. In all 4 studies, the best-performing strategy from the participants' repertoires most accurately predicted the inferences after sufficient learning opportunities. When testing SSL against 3 models representing extensions of SSL and against an exemplar model assuming a memory-based inference process, the authors found that SSL predicted the inferences most accurately. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rigorous field expressions for piecewise-sinusoidal line sources

Superposition is used to obtain expressions for the field of a line source with piecewise-sinusoidal current distribution which are rigorous even in the near zone, despite their simplicity     

Joint Adoption of QoS Schemes for MPEG Streams

Indiscriminated packet discards strongly degrade the quality perceived by end users of MPEG video transmissions. This paper investigates different Quality of Service (QoS) schemes and the tradeoffs of jointly adopting such schemes to improve the delivery quality of an MPEG stream. From an analytical model, we evaluate the impact of frame losses on the quality of MPEG streams and on the waste of network resources. Our assessment considers issues such as the use of redundancy by applying a Forward Error Correction (FEC) scheme to tolerate losses, the changing of the compression factor in MPEG encoding, the unequal protection of MPEG frames in a Differentiated Services environment, and how to evaluate the impact of network losses onto application quality. Results provide predicted bounds on the quality to be expected by end users as well as guidelines on how to take the best advantage from the joint adoption of the investigated QoS schemes.Artur Ziviani received the B.Sc. degree in Electronics Engineering in 1998 and the M.Sc. degree in Electrical Engineering (with emphasis in Computer Networking) in 1999, both from the Federal University of Rio de Janeiro (UFRJ), Brazil. In December 2003, he received the Ph.D. degree in Computer Science from the University Pierre et Marie Curie (Paris 6), Paris, France, where he has also been a lecturer during the 2003–2004 academic year. Since September 2004, he is with the National Laboratory for Scientific Computing (LNCC), located in Petr'opolis, Brazil. His major research interests are quality of service, mobile and wireless computing, Internet measurements, and grid computing.Bernd E. Wolfinger has been with the Computer Science Department of Hamburg University since 1981, where he is presently heading the Telecommunications and Computer Networks (TKRN) Subdivision. He has degrees from Universit Claude-Bernard, Lyon (Matrise, 74), University of Karlsruhe (Diploma, Mathematics 75; Ph.D., Comp. Sc. 79) and has spent long-term sabbaticals at IBM Research, Yorktown Heights, N.Y. (85), Internat. Computer Science Institute, Berkeley, Ca. (91,96), as well as at Universit P. et M. Curie, Paris (01). Dr. Wolfinger is active in Networking research since 1975, has been responsible for numerous conference organizations and has served on a variety of TPCs. He has been an editor of books and special issues of journals and has published more than 100 papers in areas such as High-speed & Mobile Networks, Real-time Communications, Traffic Engineering, Modeling, Performance Evaluation and QoS Management.Jos'e Ferreira de Rezende received the B.Sc. and M.Sc. degrees in Electronic Engineering from the Universidade Federal do Rio de Janeiro (UFRJ) in 1988 and 1991, respectively. He received the Ph.D. degree in Computer Science from the Universit Pierre et Marie-Curie, Paris, France in 1997. He was an associate researcher at LIP6 (Laboratoire dInformatique de Paris 6) during 1997. Since 1998 he is an Associate Professor at UFRJ. His research interests are in distributed multimedia applications, multipeer communication, performance evaluation and QoS aspects of high-speed, wireless and sensor networks.Otto Carlos M.B. Duarte was born in Rio de Janeiro, Brazil, on October 23, 1953. He received the Electronic Engineer degree and the M.Sc. degree in Electrical Engineering from Universidade Federal do Rio de Janeiro, Brazil, in 1976 and 1981, respectively, and the Dr. Ing. degree from ENST/ Paris, France, in 1985. Since 1978 he is a Professor at Universidade Federal do Rio de Janeiro. From January 1992 to June 1993 he has worked at MASI Laboratory in Paris 6 University. In 1995, he has spent three months at International Computer Science Institute (ICSI) associated to the University of California at Berkeley. Presently, he is heading the computer network group (Grupo de Teleinformitica e Automao—GTA). His major research interests are in high speed communications, mobility, security and QoS guarantees.Serge Fdida is a professor at the University Pierre et Marie Curie (Paris) since 1991. He received the Doctorat de 3eme Cycle in 1984, and the Habilitation a Diriger des Recherches specializing in Modelling of computer networks in 1989 from the University Pierre et Marie Curie. From 1989 to 1995, he was a Full Professor to the University Rene Descartes (Paris). His research interests are in the area of high speed networking, pervasive communication, resource management and performance analysis. He is heading the Network and Performance group of the LIP6 Laboratory (CNRS-University of Paris 6). He was a Visiting Scientist at IBM Research during the 1990/91 academic year. He was the chairman (or co-chair) of the following events: IFIP Modelling Techniques and Tools 87, IFIP High Performance Networking 94 (HPN 94), Performance of Data Communication 95 (PCN 95) and European Conference on Multimedia Applications, Services and Techniques 97 (ECMAST 97), Networked Group Communication (NGC 99) and IFIP Networking 2000. He was the editor of the proceedings of these conferences and is the author of a book on performance evaluation and a book on Networking. He is involved in many research projects in High Performance Networking in France and Europe. He was heading the RHDM Action in France for 8 years and the COST264 Action in Europe (98 02). He belongs to the FP6 network of Excellence ENEXT. He is a senior member of IEEE, a member of ACM and also involved in two IFIP working groups on networking. He is also the Co-Director of EURONETLAB, a joint laboratory established in 2001, between University Paris 6, CNRS, THALES and 6WIND, developing research and development work on QoS Routers and Radio Routers.     

Prism-based excitation wavelength selection for multicolor fluorescence coincidence measurements

We have designed and constructed a prism setup for multiple-color confocal fluorescence experiments. The prism setup permits easy selection of any color or any combination of colors from a multicolor light source, such as a mixed-gas argon-krypton-ion laser. The selected colors emerging from the prism setup are, by design, optimally overlapped in the focus of a high-numerical-aperture objective, such as that commonly used in single-molecule fluorescence experiments. The various excitation powers can be easily adjusted in this setup. We will exemplify the potential of this setup in single-molecule fluorescence emission spectroscopy.     

Materials science of carbon nanotubes: fabrication,integration, and properties of macroscopic structures of carbon nanotubes

In this Account, we summarize some of our recent studies on the materials properties of the carbon nanotubes (CNTs). The focus is on single-wall carbon nanotubes (SWNTs). We describe experiments on synthesis of SWNTs with controlled molecular structures and assembly of functional macroscopic structures. In addition, we present results on the electron field emission properties of macroscopic CNT cathodes.     

Homogeneous luminescence decay time-based assay using energy transfer from nanospheres

Following a study on the feasibility of resonance energy transfer (RET) from carboxylated nanospheres with an incorporated phosphorescent donor to a cationic polyelectrolyte/acceptor aggregate on their surface, a novel scheme for homogeneous assays is presented that is based on RET from phosphorescent biotinylated nanospheres to fluorescently labeled streptavidin (SA). The phosphorescent nanospheres, with a diameter of well below 50 nm, are made from carboxylated polyacrylonitrile and dyed with ruthenium(II)-tris-4,7-diphenyl-1,10-phenanthroline dichloride (Ru(dpp)). Due to the small size of the nanospheres and the complete extraction of the ruthenium dye into the nanospheres during the precipitation process, RET occurs from Ru(dpp) to the label if labeled SA binds to the surface of the nanospheres. Luminescence quenching by oxygen or other species present in the sample can be neglected due to the shielding effect of the polymer matrix. Based on this finding, a competitive binding assay was established, where avidin and labeled SA compete for the biotin binding sites on the nanosphere. The process of binding to the surface can be detected by measurement of the luminescence intensity or the apparent decay time which is in the order of 2.5-4.5 micros.     

Automatic segmentation of echocardiographic sequences by active appearance motion models

A novel extension of active appearance models (AAMs) for automated border detection in echocardiographic image sequences is reported. The active appearance motion model (AAMM) technique allows fully automated robust and time-continuous delineation of left ventricular (LV) endocardial contours over the full heart cycle with good results. Nonlinear intensity normalization was developed and employed to accommodate ultrasound-specific intensity distributions. The method was trained and tested on 16-frame phase-normalized transthoracic four-chamber sequences of 129 unselected infarct patients, split randomly into a training set (n = 65) and a test set (n = 64). Borders were compared to expert drawn endocardial contours. On the test set, fully automated AAMM performed well in 97% of the cases (average distance between manual and automatic landmark points was 3.3 mm, comparable to human interobserver variabilities). The ultrasound-specific intensity normalization proved to be of great value for good results in echocardiograms. The AAMM was significantly more accurate than an equivalent set of two-dimensional AAMs.     

The ad hoc return channel: a low-cost solution for Brazilian interactive digital TV

The upcoming terrestrial digital television technology brings a new class of services to traditional TV sets. A set-top box may, for example, access the Internet and send email. The interactive return channel makes these new services possible. This channel allows TV viewers to interact by sending data back to the TV broadcaster. In this article we analyze the viability of a wireless ad hoc network to implement the return channel. For this purpose, an ad hoc network is a low-cost and flexible solution. We evaluate the performance of an ad hoc return channel using the IEEE 802.11 wireless technology for different Brazilian geographical scenarios. The results show that ad hoc networking is a promising solution for the return channel of Brazilian interactive digital TV