Duplexing methods for PON systems using multimode fiber with multicarrier transmission

Deploying a PON using multimode fiber in the access network is viewed as a costeffective solution. However, a multimode fiber link exhibits a time-dispersive nature. To cope with this problem, an OFDM transmission method is used. In this work, a comparison study on several duplexing methods for this system was performed to decide upon the recommended method for the system. The choices that were examined are: TDD, FDD, WDD and SDD (time-, frequency-, wavelength- and space- division duplexing). Based on the following criteria: channel characterization, flexible bandwidth proportion, crosstalk & beat noise impairment, components-saving and system capacity, it was concluded that SDD is the most feasible one among other choices, immediately followed by WDD

Anglo-Dutch premium auctions in eighteenth-century Amsterdam

An Anglo-Dutch premium auction consists of an English auction followed by a Dutch auction, with a cash premium paid to the winner of the first round. We study such auctions used in the secondary debt market in eighteenth-century Amsterdam. This was among the first uses of auctions, or any structured market-clearing mechanism, in a financial market. We find that this market presented two distinct challenges - generating competition and aggregating information. We argue that the Anglo-Dutch premium auction is particularly well-suited to do both. Modeling equilibrium play theoretically, we predict a positive relationship between the uncertainty in a security's value and the likelihood of a second-round bid. Analyzing data on 16,854 securities sold in the late 1700s, we find empirical support for this prediction. This suggests that bidding behavior may have been consistent with (non-cooperative) equilibrium play, and therefore that these auctions were successful at generating competition. We also find evidence suggesting that these auctions succeeded at aggregating information. Thus, the Anglo-Dutch premium auction appears to have been an effective solution to a complex early market design problem

Scalability of a packet-switched WDM MAN with support for optical multicasting

This paper addresses the scalability (in terms of the number of nodes) of a packetswitched WDM all-optical bi-directional ring for metropolitan area networks. The nodes enable adding/dropping packets to/from all WDM channels on the ring. The nodes are optically transparent to data packets that bypass them. At a linespeed of 2.5 Gbps using directly modulated DFB lasers separated by 400 GHz, EDFAs to compensate for optical power loss and Phasars for wavelength multiplexing/demultiplexing it has been experimentally observed that a single ring can support upto 8 transparent nodes

The influence of the noradrenergic system on optimal control of neural plasticity

Decision making under uncertainty is challenging for any autonomous agent. The challenge increases when the environment’s stochastic properties change over time, i.e., when the environment is volatile. In order to efficiently adapt to volatile environments, agents must primarily rely on recent outcomes to quickly change their decision strategies; in other words, they need to increase their knowledge plasticity. On the contrary, in stable environments, knowledge stability must be preferred to preserve useful information against noise. Here we propose that in mammalian brain, the locus coeruleus (LC) is one of the nuclei involved in volatility estimation and in the subsequent control of neural plasticity. During a reinforcement learning task, LC activation, measured by means of pupil diameter, coded both for environmental volatility and learning rate. We hypothesize that LC could be responsible, through norepinephrinic modulation, for adaptations to optimize decision making in volatile environments. We also suggest a computational model on the interaction between the anterior cingulate cortex (ACC) and LC for volatility estimation