Local Visual Microphones: Improved Sound Extraction from Silent Video

Sound waves cause small vibrations in nearby objects. A few techniques exist in the literature that can extract sound from video. In this paper we study local vibration patterns at different image locations. We show that different locations in the image vibrate differently. We carefully aggregate local vibrations and produce a sound quality that improves state-of-the-art. We show that local vibrations could have a time delay because sound waves take time to travel through the air. We use this phenomenon to estimate sound direction. We also present a novel algorithm that speeds up sound extraction by two to three orders of magnitude and reaches real-time performance in a 20KHz video.Comment: Accepted to BMVC 201

Time Inconsistency of Trade Policy and Multilateralism

In this paper we address the issue of multilateralism versus bilateralism in a situation where a home government's optimal policy is time-inconsistent and the time-consistent policy sub-optimal. Short-run production and wage rigidities create incentive for the government to surprise private agents, ex post, with excessive protection. The problem is shown to be particularly severe when the intended beneficiaries (members of the lobby) cannot coordinate on their (investment) decisions fully. A commitment to multilateral free trade may then be welfare enhancing and politically feasible. However, once a discriminatory Preferential Trade Agreement is formed, it undermines any incentive for further multilateral trade liberalization. Thus, we propose another reason why Article XXIV of GATT/WTO may be a stumbling bloc for wider multilateral trade liberalization. Our result is based on the trade deflection effect and the market power effect of Preferential Trade Agreements.Regionalism, Time Inconsistency, Stumbling blocs

The time cost of documents to trade

This paper analyzes the relationship between the number of documents required to export and import and the time it takes to complete all procedures to trade. It shows that an increase in the number of documents required for export and import tends to increase the time cost of shipments. However, this relationship is far from simplistic, varying sharply in magnitude across rich versus poor countries and small versus large countries. Specifically, the increase in the time cost of increased documentation is much larger for relatively poor and larger countries. One interpretation of this finding is that richer countries that have more resources and smaller countries that rely more on trade invest more in building efficient documentation systems. Hence, in such countries relative to others, increased documentation adds less to the time cost at the margin. At a broader level, the findings suggest caution in interpreting how input-based measures such as the number of required documents to trade affect the quality of the business environment as far as the associated cost is concerned.Economic Theory&Research,Information Security&Privacy,Science Education,Scientific Research&Science Parks,Inequality

Competition and demographics

Mainstream economics views demographic changes in the structure of households as of little relevance for the behavior of firms or the functioning of markets. The present paper dispels this view by arguing that changes in the number of non-workers could affect the intensity with which consumers search for best prices and therefore the level of competition. The author also analyzes the relationship between income and competition, which some studies suggest is negative. The author argues that the negative relationship is most likely due to the demographic factors discussed.Markets and Market Access,Education for Development (superceded),Economic Theory&Research,Labor Policies,Emerging Markets

Imperfect Competition and the Theory of Managed Trade

We analyze the role of imperfect competition in explaining the relationship between temporary surges in trade-volumes and the level of cooperation in trade policy that can be sustained between countries in a repeated game framework. Imperfectly competitive markets are characterized by a mark-up which is the wedge between equilibrium price and the marginal cost of production. Absent domestic policy tools, gains from protectionist policies are shown to depend positively on the size of the mark-up in the domestic import-competing sector, which is in addition to the conventional terms-of-trade related benefits. A temporary surge in trade-volume due to a supply-side shock lowers the industry mark-up making protectionist policies less desirable. This counters the increase in the terms-of-trade related benefits due to higher trade-volume. The net effect of these two competing forces determines whether periods of abnormally high trade-volumes feature more or less cooperation along the equilibrium path of the repeated game. We identify simple conditions distinguishing between these two outcomes thereby establishing the pattern of "managed trade" under imperfect competition. A sharp distinction is drawn between demand side and supply side shocks. We suggest a simple generalization of the results to other forms of distortions.Managed Trade, Imperfect Competition, Repeated Game, Trade Policy

Helpful Governments

This paper provides an alternative way of testing the theory of legal origins, one based on a firm's perception of how helpful the government is for doing business. The author argues that an approach based on firm perceptions offers a number of advantages over existing studies. Specifically, the analysis demonstrates that heavier regulation in civil law compared with common law countries is not viewed by businesses as an efficient and socially desirable response to disorder. Further, the findings show a strong effect of legal tradition on government helpfulness even after controlling for various institutional measures known to be correlated with the legal tradition of countries. This suggests that there is more to legal tradition than what existing studies have unearthed.National Governance,Legal Products,Public Sector Corruption&Anticorruption Measures,Governance Indicators,Debt Markets

Perfectly Secure Index Coding

In this paper, we investigate the index coding problem in the presence of an eavesdropper. Messages are to be sent from one transmitter to a number of legitimate receivers who have side information about the messages, and share a set of secret keys with the transmitter. We assume perfect secrecy, meaning that the eavesdropper should not be able to retrieve any information about the message set. We study the minimum key lengths for zero-error and perfectly secure index coding problem. On one hand, this problem is a generalization of the index coding problem (and thus a difficult one). On the other hand, it is a generalization of the Shannon's cipher system. We show that a generalization of Shannon's one-time pad strategy is optimal up to a multiplicative constant, meaning that it obtains the entire boundary of the cone formed by looking at the secure rate region from the origin. Finally, we consider relaxation of the perfect secrecy and zero-error constraints to weak secrecy and asymptotically vanishing probability of error, and provide a secure version of the result, obtained by Langberg and Effros, on the equivalence of zero-error and $\epsilon$-error regions in the conventional index coding problem.Comment: 25 pages, 5 figures, submitted to the IEEE Transactions on Information Theor

Non-Asymptotic Output Statistics of Random Binning and Its Applications

In this paper we develop a finite blocklength version of the Output Statistics of Random Binning (OSRB) framework. The framework is shown to be optimal in the point-to-point case. New second order regions for broadcast channel and wiretap channel with strong secrecy criterion are derived.Comment: A shot version has been submitted to ISIT 201