A study of structural and parametric learning in XCS

The performance of a learning classifier system is due to its two main components. First, it evolves new structures by generating new rules in a genetic process; second, it adjusts parameters of existing rules, for example rule prediction and accuracy, in an evaluation step, which is not only important for applying the rules, but also for the genetic process. The two components interleave and in the case of XCS drive the population toward a minimal, fit, non-overlapping population. In this work we attempt to gain new insights as to the relative contributions of the two components. We find that the genetic component has an additional role when using the train/test approach which is not present in online learning. We compare XCS to a system in which the rule set is restricted to the initial random population (XCS-NGA, that is, XCS No Genetic Algorithm). For small Boolean functions we can give XCS-NGA all possible rules of a particular condition length. In online learning, XCS-NGA can, given sufficiently many rules, achieve a surprisingly high classification accuracy, comparable to that of XCS. In a train/test approach, however, XCS generalises better than XCS-NGA and there seem to be limitations of XCS-NGA which cannot be overcome simply by increasing the population size. This illustrates that the requirements of a function approximator tend to differ between reinforcement learning (which is typically online) and concept learning (which is typically train/test).     

Computex2008我眼中的新科技

2008年6月3日,台北电脑展（COMPUTEX TAIPEI）拉开序幕,作为亚洲最大、世界第二大（仅次于德国汉诺威CeBIT）的电脑展,英特尔、惠普、宏基等业界巨头每年都会参与本展,并于展览期间发表新产品。对于如此重要的展会,我们也会想方设法去了解和接触,今天我们的特派员Tim也亲临了现场,让我们通过这位台北资深电脑玩家的眼来了解展会上的新技术、新发展和新趋势吧。     

Processing of Emotional Information in Seasonal Depression Across Different Cognitive Measures.

This study examined memory for emotional material, endorsement of emotional adjectives, and negative attributional style (NAS) in seasonal affective disorder (SAD). SAD patients showed elevated NAS and increased endorsement of negative self-referent adjectives, but no memory bias for negative material, when compared with never-depressed controls. Longitudinal analyses revealed that none of these cognitive measures significantly predicted later symptom levels independent of initial symptom levels, in the SAD patients. The cross-sectional findings for adjective endorsement and memory were replicated in a second experiment. These data provide further evidence that depression-related memory effects in SAD are different from those found in nonseasonal depression. Accounts of these differences involving putative mood-repair processes and/or an absence of dysfunctional negative schemas in SAD are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Near-simultaneous dual energy range EELS spectrum imaging

A system that allows the collection of the low loss spectrum and the core loss spectrum, covering different energy regions, at each pixel in a spectrum image is described. It makes use of a fast electrostatic shutter with control signals provided by the spectrum imaging software and synchronisation provided by the CCD camera controller. The system also allows simultaneous collection of the X-ray spectrum and the signals from the imaging detectors while allowing the use of the existing features of the spectrum imaging software including drift correction and sub-pixel scanning. The system allows acquisition of high-quality spectra from both the core and the low loss regions, allowing full processing of the EELS data. Examples are given to show the benefits, including deconvolution, absolute thickness mapping and determination of numbers of atoms per unit area and per unit volume. Possible further developments are considered.     

Fault detection and diagnosis of networked control system

Consider the plant of Multiple-input Networked Control System (NCS) with long reduced delay. The effect of the disturbances to the NCS is discussed and the iterative method is used to compensate the delay when design a reduced-order state observer with a γ-stability margin (0 相似文献   

ACPI and SMI handlers: some limits to trusted computing

Trusted computing has been explored through several international initiatives. Trust in a platform generally requires a subset of its components to be trusted (typically, the CPU, the chipset and a virtual machine hypervisor). These components are granted maximal privileges and constitute the so called Trusted Computing Base (TCB), the size of which should be minimal. The rest of the platform is only granted limited privileges and cannot perform security-critical operations. A few initiatives aim at excluding the BIOS from the TCB in particular (e.g., Intel^® TxT and AMD SVM/SKINIT). However, the BIOS is responsible for providing some objects that need to be trusted for the computer to work properly. This paper focuses on two of these objects, the SMI handler and the ACPI tables, which are responsible for the configuration and the power management of the platform. We study to what extent these two components shall reasonably be trusted. Despite the protections that are implemented, we show that an attacker can hide functions in either structure to escalate privileges. The main contributions of our work are to present an original mechanism that may be used by attackers to alter the SMI handler, and to describe how rogue functions triggered by an external stimulus can be injected inside ACPI tables (in our case, the attacker will plug and unplug the power supply twice in a row). We also explore the countermeasures that would prevent such modifications.     

Tuning the dielectric properties of hafnium silicate films

The influence of Si concentration in hafnium silicate dielectrics on thermal stability and dielectric permittivity was analyzed. A phase diagram was developed using GIXRD and FTIR measurement. The stabilization of the “higher-k” cubic/tetragonal phase for annealing temperatures up to 1000 °C with a steady increase in capacitance was demonstrated for Hf_0.94Si_0.06O₂ films. It was also shown that the stabilization of nano-crystalline Hf_0.80Si_0.20O₂ films can be realized for annealing temperatures up to 900 °C. The influence of TiN electrodes on the dielectric constant and the leakage current characteristic was also investigated. A permittivity increase for annealing temperatures up to 1000 °C without degradation of leakage current was shown.     

Docosahexaenoic Acid Modulates Paracellular Absorption of Testosterone and Claudin-1 Expression in a Tissue-Engineered Skin Model

Healthy skin moLEdels produced by tissue-engineering often present a suboptimal skin barrier function as compared with normal human skin. Moreover, skin substitutes reconstructed according to the self-assembly method were found to be deficient in polyunsaturated fatty acids (PUFAs). Therefore, in this study, we investigated the effects of a supplementation of the culture media with docosahexaenoic acid (DHA) on the barrier function of skin substitutes. To this end, 10 μM DHA-supplemented skin substitutes were produced (n = 3), analyzed, and compared with controls (substitutes without supplementation). A Franz cell diffusion system, followed by ultra-performance liquid chromatography, was used to perform a skin permeability to testosterone assay. We then used gas chromatography to quantify the PUFAs found in the epidermal phospholipid fraction of the skin substitutes, which showed successful DHA incorporation. The permeability to testosterone was decreased following DHA supplementation and the lipid profile was improved. Differences in the expression of the tight junction (TJ) proteins claudin-1, claudin-4, occludin, and TJ protein-1 were observed, principally a significant increase in claudin-1 expression, which was furthermore confirmed by Western blot analyses. In conclusion, these results confirm that the DHA supplementation of cell culture media modulates different aspects of skin barrier function in vitro and reflects the importance of n-3 PUFAs regarding the lipid metabolism in keratinocytes.     

System identification for chaotic integrate-and-fire dynamics

We discuss applications of the fact that dynamical state information can be reconstructed from a series of interspike interval (ISI) measurements. This system analysis allows system identification and prediction from spike train history. Secondly, using this reconstruction, unstable periodic trajectories of the underlying system can be controlled by small changes in a system parameter. The underlying assumption is an integrate-and-fire model coupling the dynamical system to the observable spike train. © 1997 John Wiley & Sons, Inc.