Controlled analysis of neurocontrollers with informational lesioning

How does one aim to understand neural information processing? One of the difficult first challenges is to identify the roles of the network's elements. To this end a functional contribution analysis (FCA) method has been developed and applied for studying the neurocontrollers of evolutionary autonomous agents (EAAs). The FCA processes data composed of multiple lesion experiments and the corresponding performance levels that the agent obtains under these lesions. It calculates the contribution values (CVs) of the network's elements such that the ability to predict the agent's performance under new, unseen lesions is maximized. Previous analysis has found a strong dependence of the CVs and the prediction error on the specific type of lesioning method used, i.e. on the way in which the activity of lesioned neurons is disrupted. We present a new, informational lesioning method (ILM), which views a lesion as a noisy channel and applies a controlled lesion to the network by varying the lesioning level from large to arbitrarily small magnitudes. Studying the ILM within the FCA framework, our main results are threefold: first, that lower lesioning levels permit more accurate FCA predictions; second, that the usage of minute ILM lesioning levels can uncover the long-term effects of elements on the network's functioning; and third, that as the lesioning level decreases, the CVs tend to approach limit values, reflecting the importance of these elements in the intact, normal-functioning neurocontroller.     

On the deployment of a real scalable delegation service

This paper explains the evolution of the concept of delegation since its first references in the context of distributed authorization to the actual use as a fundamental part of a privilege management architecture. The work reviews some of the earliest contributions that pointed out the relevance of delegation when dealing with distributed authorization, in particular we comment on PolicyMaker and KeyNote, and also on SDSI/SPKI. Then, we elaborate on Federation as a particular case of delegation, and remark the importance given to Federation by the industry. Finally, the paper discusses about Privilege Management Infrastructures, introducing a new mechanism to extend their functionality using advanced delegation services.     

Performance improvement of web caching in Web 2.0 via knowledge discovery

Web 2.0 systems are more unpredictable and customizable than traditional web applications. This causes that performance techniques, such as web caching, limit their improvements. Our study was based on the hypotheses that the use of web caching in Web 2.0 applications, particularly in content aggregation systems, can be improved by adapting the content fragment designs. We proposed to base this adaptation on the analysis of the characterization parameters of the content elements and on the creation of a classification algorithm. This algorithm was deployed with decision trees, created in an off-line knowledge discovery process. We also defined a framework to create and adapt fragments of the web documents to reduce the user-perceived latency in web caches. The experiment results showed that our solution had a remarkable reduction in the user-perceived latency even losses in the cache hit ratios and in the overhead generated on the system, in comparison with other web cache schemes.     

Innovative Data Acquisition for Heavily Instrumented Flexible Pavements

A data acquisition program was written to allow independent triggering of multiple test sections of a thin flexible pavement. A total of 129 electronic sensors were installed in 17 test sections and subjected to 2,100 truck passes over several months immediately after construction. The measured strains were highly variable in the thin flexible pavement, but the program was still able to successfully trigger each section independently. The majority of signal processing was also performed within the program, which was written in Lab VIEW 7 Express. This approach significantly reduced the amount of postprocessing effort that would have otherwise been required. The quality of the triggering approach was compared to independently collected weigh in motion data. The majority of the test sections recorded within 0.5% of the number of vehicles recorded by the weigh in motion system. Key components of all major facets of the data acquisition and programming performed are discussed in detail.     

Characterization of polymeric film of a new manganese phthalocyanine complex octa-substituted with 2-diethylaminoethanethiol, and its use for the electrochemical detection of bentazon

Manganese acetate octakis-(2-diethyaminoethanethiol) phthalocyanine (AcMnODEAETPc) was newly synthesized and characterized by spectroscopic and electrochemical methods. Solution electrochemistry of the complex showed three redox processes assigned to Mn^IIIPc⁻¹/Mn^IIIPc⁻², Mn^IIIPc⁻²/Mn^IIPc⁻² and Mn^IIPc⁻²/Mn^IIPc⁻³ species. The new molecule was polymerized onto a glassy carbon electrode (GCE) to form thin films of different thickness, giving poly-10-AcMnODEAETPc-GCE, poly-20-AcMnODEAETPc-GCE and poly-30-AcMnODEAETPc-GCE, where 10, 20 and 30 represent the number of voltammetry scans during polymerization. Three distinct redox processes were observed on the modified electrode in 0.1 M phosphate buffer solution, pH 5, which confirmed the formation of the polymer. The current signal due to the herbicide, bentazon, was dependent on film thickness; the best signal was obtained on poly-20-AcMnODEAETPc-GCE while poly-10-AcMnODEAETPc-GCE gave the least signal. However, the signals due to the herbicide were better on the different films compared to the bare electrode. Electrochemical impedance spectroscopy (EIS) technique revealed that differences in film thickness offered different charge transfer resistances, R_ct, hence difference in current signals for bentazon oxidation were observed on these films. A Tafel slope of 77 mV/decade, obtained for the herbicide on poly-20-AcMnODEAETPc-GCE, denotes a fast one electron transfer followed by a slow chemical step in the electro-oxidation of bentazon. The voltammetry signals of the herbicide on the films indicated the likely involvement of ring-based redox processes in the detection of the herbicide. A plot of background corrected current response, on this film, versus the concentration of bentazon was linear within the range 50–750 μM with a detection limit of 2.48 × 10⁻⁷ M.     

Real time virtual window management for bit mapped raster graphics

In this paper we present a hardware real time window system which uses a virtual address mapping scheme based on associative memory. Until now, bit block transfer operations were used to update screen contents from main memory window information. Since these operations transfer large blocks of data from main memory to the frame buffer whenever window parameters are changed, response times of window systems were slow. With the proposed approach, the frame buffer may be completely eliminated and replaced by a large virtual video memory which is capable of holding all the window data in non-overlapping locations. Mapping becomes now a dynamic real-time function which assigns screen addresses to different areas of the virtual video memory at different times.     

Reframing the Iraq War: Official Sources,Dramatic Events,and Changes in Media Framing

This study examines how official sources and dramatic events influence media framing of political issues, assessing the claims of the indexing hypothesis and event-driven models. Through an analysis of the New York Times' coverage of the Iraq War in late 2005 and early 2006, this study compares coverage from before and after the bombing of a major Shi'ite shrine in Iraq. The analysis shows that journalists avoided the preferred frame of the White House while amplifying the preferred frame of the military. It also shows that the bombing spurred journalists to reframe the conflict. These findings challenge parts of the indexing hypothesis and support a more event-driven model of media framing.     

Effect of cassava varieties on the sorption isotherm of tapioca grits

Cassava (Manihot esculenta Cranzt) deteriorates rapidly. Hence it is processed into various products within 2 to 3 days after harvesting. For this work, tapioca was produced from three different varieties of cassava. They are Odongbo, Okoiyawo and TMS30572. The sorption isotherm for the tapioca grits from three different varieties of cassava at temperatures 25, 32 and 45 °C were determined experimentally and modelled using five different models. Using analysis of variance at 0.01 level, it was shown that the experimental sorption isotherms of the tapioca from the various cassava varieties are not significantly different from each other. However, the Guggenheim (1966) , Anderson (1946) & de Boer (1953) (GAB) model gave the best fit for sorption isotherm of tapioca from either the Odongbo or Okoiyawo varieties, while the exponential model was the best for that from TMS30572 variety.     

Control of vertebrate left-right asymmetry by a snail-related zinc finger gene

A gene encoding a zinc finger protein of the Snail family, cSnR, is expressed in the right-hand lateral mesoderm during normal chick development. Antisense disruption of cSnR function during the hours immediately preceding heart formation randomized the normally reliable direction of heart looping and subsequent embryo torsion. Implanted ectopic sources of intercellular signal proteins that are involved in establishing normal left-right information randomized the handedness of heart development and also altered the asymmetry of cSnR expression. cSnR thus appears to act downstream of these signals, or perhaps in parallel with the latest expressed of them, the Nodal protein, in controlling the anatomical asymmetry.