Bandwidth Efficient Root Nyquist Pulses for Optical Intensity Channels

Indoor diffuse optical intensity channels are bandwidth constrained due to the multiple reflected paths between the transmitter and the receiver which cause considerable inter-symbol interference (ISI). The transmitted signal amplitude is inherently non-negative, being a light intensity signal. All optical intensity root Nyquist pulses are time-limited to a single symbol interval which eliminates the possibility of finding bandlimited root Nyquist pulses. However, potential exists to design bandwidth efficient pulses. This paper investigates the modified hermite polynomial functions and prolate spheroidal wave functions as candidate waveforms for designing spectrally efficient optical pulses. These functions yield orthogonal pulses which have constant pulse duration irrespective of the order of the function, making them ideal for designing an ISI free pulse. Simulation results comparing the two pulses and challenges pertaining to their design and implementation are discussed

A comparative study of game theoretic and evolutionary models for software agents

Most of the existing work in the study of bargaining behaviour uses techniques from game theory. Game theoretic models for bargaining assume that players are perfectly rational and that this rationality in common knowledge. However, the perfect rationality assumption does not hold for real-life bargaining scenarios with humans as players, since results from experimental economics show that humans find their way to the best strategy through trial and error, and not typically by means of rational deliberation. Such players are said to be boundedly rational. In playing a game against an opponent with bounded rationality, the most effective strategy of a player is not the equilibrium strategy but the one that is the best reply to the opponent's strategy. The evolutionary model provides a means for studying the bargaining behaviour of boundedly rational players. This paper provides a comprehensive comparison of the game theoretic and evolutionary approaches to bargaining by examining their assumptions, goals, and limitations. We then study the implications of these differences from the perspective of the software agent developer

An anytime approximation method for the inverse Shapley value problem

Coalition formation is the process of bringing together two or more agents so as to achieve goals that individuals on their own cannot, or to achieve them more efficiently. Typically, in such situations, the agents have conflicting preferences over the set of possible joint goals. Thus, before the agents realize the benefits of cooperation, they must find a way of resolving these conflicts and reaching a consensus. In this context, cooperative game theory offers the voting game as a mechanism for agents to reach a consensus. It also offers the Shapley value as a way of measuring the influence or power a player has in determining the outcome of a voting game. Given this, the designer of a voting game wants to construct a game such that a players Shapley value is equal to some desired value. This is called the inverse Shapley value problem. Solving this problem is necessary, for instance, to ensure fairness in the players voting powers. However, from a computational perspective, finding a players Shapley value for a given game is #p-complete. Consequently, the problem of verifying that a voting game does indeed yield the required powers to the agents is also #P-complete. Therefore, in order to overcome this problem we present a computationally efficient approximation algorithm for solving the inverse problem. This method is based on the technique of successive approximations; it starts with some initial approximate solution and iteratively updates it such that after each iteration, the approximate gets closer to the required solution. This is an anytime algorithm and has time complexity polynomial in the number of players. We also analyze the performance of this method in terms of its approximation error and the rate of convergence of an initial solution to the required one. Specifically, we show that the former decreases after each iteration, and that the latter increases with the number of players and also with the initial approximation error. Copyright © 2008, International Foundation for Autonomous Agents and Multiagent Systems (www.ifaarnas.org). All rights reserved

Morphisms from P2 to Gr(2,C4)

In this note we study morphisms from P2 to Gr(2,C4) from the point of view of the cohomology class they represent in the Grassmannian. This leads to some new result about projection of d-uple imbedding of P2 to P5

Slotting Allowance: an Overlooked Angle in Grocery Retailing

Ever wonder why one product brand enjoys a more prominent shelf location in a particular retail establishment than another brand? Would such arrangement have any impact on the price one pays for a particular product? Answers to these are related to the relatively unexplored business phenomenon known as slotting allowances or fees for store shelf space. Read more about it...slotting allowance, retail market, distribution market, intermediate market, shelf space rental fee, product brand, store shelf space

Linear Algorithm for Conservative Degenerate Pattern Matching

A degenerate symbol x* over an alphabet A is a non-empty subset of A, and a sequence of such symbols is a degenerate string. A degenerate string is said to be conservative if its number of non-solid symbols is upper-bounded by a fixed positive constant k. We consider here the matching problem of conservative degenerate strings and present the first linear-time algorithm that can find, for given degenerate strings P* and T* of total length n containing k non-solid symbols in total, the occurrences of P* in T* in O(nk) time

Modulation of APP Processing and Amyloid-P Levels by Human 82-kDa Choline Acetyltransferase

The 82-kDa isoform of choline acetyltransferase (82-ChAT) is unique to primates and is found in cholinergic cell nuclei. The functional significance of this protein is not well understood. Previous studies showed that nuclear 82-ChAT levels decrease with advancing age, and this is accelerated in Alzheimer’s disease (AD). The present studies examined the effect of 82-ChAT on amyloid precursor protein (APP) metabolism and amyloid-P (Ap) production. Levels of enzymes involved in processing of APP were examined in human SH-SY5Y neuroblastoma cells and in primary neuronal cultures prepared from cerebral cortex of embryonic APP/PS1 double transgenic mice that serve as a model of AD. A significant amount of APi^2 was released into cell culture media from neurons cultured from transgenic mice for 8 DIV, and this was associated with an elevation of total APP levels rather than changes in levels of APP processing enzymes. Upon expression of 82-ChAT, a 20% reduction in AP-m2 release was found when compared to GFP-expressing control neurons. This was associated with a significant reduction in the protein but not mRNA of the p-secretase BACE1, indicating that 82-ChAT may alter proteins involved in post-translational modification and regulation of BACE1. These studies have important implications for AD pathology and broaden our understanding of the function of 82-ChAT proteins

Hunger Incidence in the Philippines: Facts, Determinants and Challenges

The high level of hunger incidence in the country is perhaps one of the most pressing issues that need to be addressed by our policy makers. Official government statistics and data from self-rated hunger surveys show an increasing trend in hunger incidence among Filipino households. Data from National Statistical Coordination Board (NSCB) show that the percentage of subsistence poor in the country increased to 14.6 percent in 2006 from 13.5 percent in 2003. The Social Weather Stations (SWS) quarterly surveys on hunger incidence also show an increasing trend in the percentage of families that experienced hunger, reaching an alarming level of 24 percent in December 2009, representing about 4.4 million households. One probable cause of the increasing trend in hunger is the rising food prices akin to what the country experienced in 2008. This paper aims to determine the impact of food inflation and underemployment on hunger incidence in the Philippines, using the hunger incidence data from the SWS quarterly surveys on hunger. A vector autoregressive (VAR) model is used to determine the effect of a shock or increase to food inflation and underemployment on total involuntary hunger. Results from the model show that an increase in food prices at the current quarter will increase hunger incidence for a period of five quarters, starting with immediate quarter after the shock occurred. Shocks to underemployment will also increase hunger incidence but the effects last for only two quarters, also starting with immediate quarter after the shock. The results of this study provide relevant information that will be useful in crafting policies related to the Hunger Mitigation Program of the government.hunger; food inflation; underemployment; vector autoregressive models