Random Access Game in Fading Channels with Capture: Equilibria and Braess-like Paradoxes

The Nash equilibrium point of the transmission probabilities in a slotted ALOHA system with selfish nodes is analyzed. The system consists of a finite number of heterogeneous nodes, each trying to minimize its average transmission probability (or power investment) selfishly while meeting its average throughput demand over the shared wireless channel to a common base station (BS). We use a game-theoretic approach to analyze the network under two reception models: one is called power capture, the other is called signal to interference plus noise ratio (SINR) capture. It is shown that, in some situations, Braess-like paradoxes may occur. That is, the performance of the system may become worse instead of better when channel state information (CSI) is available at the selfish nodes. In particular, for homogeneous nodes, we analytically present that Braess-like paradoxes occur in the power capture model, and in the SINR capture model with the capture ratio larger than one and the noise to signal ratio sufficiently small.Comment: 30 pages, 5 figure

Translation of EEG spatial filters from resting to motor imagery using independent component analysis.

Electroencephalogram (EEG)-based brain-computer interfaces (BCIs) often use spatial filters to improve signal-to-noise ratio of task-related EEG activities. To obtain robust spatial filters, large amounts of labeled data, which are often expensive and labor-intensive to obtain, need to be collected in a training procedure before online BCI control. Several studies have recently developed zero-training methods using a session-to-session scenario in order to alleviate this problem. To our knowledge, a state-to-state translation, which applies spatial filters derived from one state to another, has never been reported. This study proposes a state-to-state, zero-training method to construct spatial filters for extracting EEG changes induced by motor imagery. Independent component analysis (ICA) was separately applied to the multi-channel EEG in the resting and the motor imagery states to obtain motor-related spatial filters. The resultant spatial filters were then applied to single-trial EEG to differentiate left- and right-hand imagery movements. On a motor imagery dataset collected from nine subjects, comparable classification accuracies were obtained by using ICA-based spatial filters derived from the two states (motor imagery: 87.0%, resting: 85.9%), which were both significantly higher than the accuracy achieved by using monopolar scalp EEG data (80.4%). The proposed method considerably increases the practicality of BCI systems in real-world environments because it is less sensitive to electrode misalignment across different sessions or days and does not require annotated pilot data to derive spatial filters

Comparison of American and Chinese College Students by Means of the Holtzman Inkblot Technique

The major purpose of this study was to explore personality differences between American and Chinese college students. Sixteen American college students and two groups of the same number of their Chinese counterparts, one of the Chinese student groups being in the United States for less than one year and the other group being in the United States for longer than two years, were randomly selected and matched by ages to be the subjects of this study. The Holtzman Inkblot Technique (HIT) was administered to all forty-eight subjects by the author and the HIT protocols were scored by two different scorers who have previously been trained in projective techniques, and did not have any knowledge of the subjects. Twenty-two HIT scoring variables were obtained among these three groups of subjects. Two Analyses of Variance (ANOVA) were undertaken. A 3x2x45 factorial ANOVA design was used to evaluate latency time among the three groups, as it is related to the effects of different nationality, sex, and inkblots. A 3x2x2x21 factorial ANOVA design was used to evaluate the remaining 21 HIT variables considering the effects of different nationality, sex, judges, and the variables. The inter-scorer reliability coefficients were also estimated. The results of this study found (1) American and Chinese college students do differ in latency when responding to the HIT inkblots. American college students tended to have longer latency than their Chinese counterparts. Cultural and environmental changes do seem to affect people\u27s perception as revealed in responses to the HIT. The Chinese group II, which had been in the United States longer than two years, had a mean latency time very close to its American counterpart, while the Chinese group I, which had been in the United States less than a year, had the shortest latency time. Male and female differences on latency were found to be non-significant. (2) The inkblots themselves have significant differences in inducing latency differences. Certain inkblots seemed to require a greater amount of time for a subject to respond than others. (3) The main effects of nationality, and of judge alone were found to be non-significant for the remaining 21 HIT variables. Neither nationality nor judge was a main factor in determining cross-cultural differences between American and Chinese college students. (4) Differences between the HIT variables in terms of occurrence frequency in a protocol seem to be significant. (5) Certain HIT variables seem to cause more inter-scoring disagreement than others. (6) Judges did show discrepancies when scoring certain variables of different nationality group\u27s HIT protocols. (7) The HIT may not be a sensitive instrument to measure the assimilation of a foreign culture over a long period of time. As was the case in this study, nationality factor alone was not found to be significant

Survey: Woman and California Law

This survey of California, a regular feature of the Women\u27s Law Forum, summarizes recent California Supreme Court and Court of Appeal decisions of special importance to women. A brief analysis of the issues pertinent to women raised in each case is provided

Survey: Woman and California Law

This survey of California, a regular feature of the Women\u27s Law Forum, summarizes recent California Supreme Court and Court of Appeal decisions of special importance to women. A brief analysis of the issues pertinent to women raised in each case is provided

Tree Ring Characteristics of 30-Year-Old Swietenia Macrophylla Plantation Trees

Ring characteristics of mahogany (Swietenia macrophylla K.) plantation trees grown in Taiwan were explored. Significant differences in average ring width (RW) and ring density (RD) occurred among three tree-diameter classes and three radial stages of ring numbers. RW in the radial direction decreased from the pith outward to the bark and followed a distinctive three-stage variation pattern (juvenile, transition, and mature zones). RD in the radial direction increased slowly from the pith outward to the bark. Wider tree rings and lower density are associated with juvenile wood close to the pith, whereas narrower tree rings and higher density are typical for mature wood outward toward the bark. RD in overtopped trees was higher than that in dominant trees. However, RW in dominant trees was wider than that in intermediate and overtopped trees. Earlywood density, latewood density, maximum density, and minimum density were the most important factors determining overall RD. There was a weak relationship between RW and RD, indicating that it is unlikely for growth rates of mahogany plantation trees to have a significant impact on wood density