Contracting and the division of the gains from trade

This paper examines the microstructure of import markets and the division of the gains from trade among consumers, importers and exporters. When exporters and importers transact through anonymous markets, double marginalization and business stealing among competing importers lead to lower profits. Trading parties can overcome these inefficiencies by investing in richer contractual arrangements such as bilateral contracts that eliminate double marginalization and joint contracts that also internalize business stealing. Introducing these contractual choices into a trade model with heterogeneous exporters and importers, we show that trade liberalization increases the incentive to engage in joint contracts, thus raising the profits of exporters and importers at the expense of consumer welfare. We examine the implications of the model for prices, quantities and exporter-importer matches in Colombian import markets before and after the US-Colombia free trade agreement. US exporters that started to enjoy dutyfree access were more likely to increase their average price, decrease their quantity exported and reduce the number of import partners

Modeling of Congestion: A Tool for Urban Traffic Management in Developing Countries

In order to formulate rational traffic management measures for urban roads, it is essential to understand the effect of different types of vehicle on congestion. The effect of different types of vehicle on congestion has been captured on the basis of marginal congestion. Using congestion models, the marginal congestions have been estimated for different road widths, traffic compositions and on-street parking levels. The peak hour vehicular composition and volume level vary for different roads in an urban area. Therefore, for assessing the operating conditions for different roads based on a comparable quantitative measure, the marginal congestion caused per Passenger Car Unit (PCU) of mixed traffic stream has been estimated and denominated ‘Marginal Congestion Index (MCI)’. The use of MCI for prioritization of management actions for different urban roads is discussed. It is shown that a congestion model explicitly accounts for the effects of traffic composition and volume level. Therefore, the effect of different types of vehicles on congestion at all traffic volumes could be estimated using congestion models. Altogether, modeling of congestion is established as a tool for formulating rational traffic management measures for urban roads in developing countries

Firm-to-firm connections in Colombian imports

The vast majority of world trade flows is between firms. Only recently has research in international trade started to emphasize the importance of the connections between exporters and importers both in aggregate trade flows and in the negative relationship between trade and geographic distance. This chapter documents the role of firm-to-firm connections in trade flows and the formation and duration of these importer-exporter relationships. Using customs data from Colombia for 1995-2014, we are able to identify both the Colombian importing firm and the foreign exporter in every Colombian import and export transaction. We document both the nature of these bilateral trading relationships and their evolution over time

Design of phase change Ge2Sb2Te5 based on-off electro-optic switch

Design of electro-optic ON-OFF switches based on well-known phase change material Ge2Sb2Te5(GST) is presented. The electro-optic switch is achieved by implementing by co-directional coupling between a 220 nm thick silicon nanowire and a silicon waveguide topped with ITO-GST-ITO layers at the 1.55μm wavelength. By introducing the electric field via the ITO electrodes, the GST layer can be changed between the amorphous and crystalline states. As the modal loss in the crystalline state is much higher than the amorphous state, through a rigorous modal analysis of the coupled silicon nanowire and GST waveguide by using the finite element method, the optimal ITO spacing is obtained at 75nm which is less sensitive to device parameter variations and thus offering better tolerances. The GST thickness is also optimized for the phase matching point at 25 nm in order to efficiently transfer power from silicon nanowire to GST waveguide to attain the OFF state. Once the device is phase matched in crystalline state, the power in the amorphous state will pass with very little interaction with the GST waveguide resulting in an ON state. The Eigenmode Expansion Method of Fimmprop is used as a junction analysis approach to calculate the optical power coupling efficiencies to the output silicon nanowire. The extinction ratio of the electro-optic switch and insertion loss in ON state at phase matching can be obtained as a function of the device length. A compact 1.75 μm long device shows a high extinction ratio of 22 dB with an insertion loss of only 0.56 dB

Open-Retrieval Conversational Question Answering

Conversational search is one of the ultimate goals of information retrieval. Recent research approaches conversational search by simplified settings of response ranking and conversational question answering, where an answer is either selected from a given candidate set or extracted from a given passage. These simplifications neglect the fundamental role of retrieval in conversational search. To address this limitation, we introduce an open-retrieval conversational question answering (ORConvQA) setting, where we learn to retrieve evidence from a large collection before extracting answers, as a further step towards building functional conversational search systems. We create a dataset, OR-QuAC, to facilitate research on ORConvQA. We build an end-to-end system for ORConvQA, featuring a retriever, a reranker, and a reader that are all based on Transformers. Our extensive experiments on OR-QuAC demonstrate that a learnable retriever is crucial for ORConvQA. We further show that our system can make a substantial improvement when we enable history modeling in all system components. Moreover, we show that the reranker component contributes to the model performance by providing a regularization effect. Finally, further in-depth analyses are performed to provide new insights into ORConvQA.Comment: Accepted to SIGIR'2

Combined burden and functional impact tests for cancer driver discovery using DriverPower

The discovery of driver mutations is one of the key motivations for cancer genome sequencing. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2658 cancers across 38 tumour types, we describe DriverPower, a software package that uses mutational burden and functional impact evidence to identify driver mutations in coding and non-coding sites within cancer whole genomes. Using a total of 1373 genomic features derived from public sources, DriverPower's background mutation model explains up to 93% of the regional variance in the mutation rate across multiple tumour types. By incorporating functional impact scores, we are able to further increase the accuracy of driver discovery. Testing across a collection of 2583 cancer genomes from the PCAWG project, DriverPower identifies 217 coding and 95 non-coding driver candidates. Comparing to six published methods used by the PCAWG Drivers and Functional Interpretation Working Group, DriverPower has the highest F1 score for both coding and non-coding driver discovery. This demonstrates that DriverPower is an effective framework for computational driver discovery

Great Expectations: Plans and Predictions for New Horizons Encounter with Kuiper Belt Object 2014 MU69 ('Ultima Thule')

The New Horizons encounter with the cold classical Kuiper Belt object (KBO) 2014 MU69 (informally named 'Ultima Thule,' hereafter Ultima) on 1 January 2019 will be the first time a spacecraft has ever closely observed one of the free-orbiting small denizens of the Kuiper Belt. Related to but not thought to have formed in the same region of the Solar System as the comets that been explored so far, it will also be the largest, most distant, and most primitive body yet visited by spacecraft. In this letter we begin with a brief overview of cold classical KBOs, of which Ultima is a prime example. We give a short preview of our encounter plans. We note what is currently known about Ultima from earth-based observations. We then review our expectations and capabilities to evaluate Ultima's composition, surface geology, structure, near space environment, small moons, rings, and the search for activity

Targeting sustainable competitiveness in Croatia by implementation of “20 Keys” methodology

Throughout the current wave of regulatory reforms, several theoretical models have been proposed that call for the emergence of instruments of self-regulation under some form of state supervision as part of the demand to improve product development performances aligned with awareness of environmental needs, to help with meeting regulation and to reduce the risk of production nonconformance. “20 Keys” is one example of a mass application of a methodology for raising sustainable development and holistic approach to competitiveness in new EU member the Republic of Croatia, and therefore, the aim of this study is to observe the results of the methodology application in Croatian companies. 20 Keys is a methodology that brings an integrated set of tools aimed at increasing overall productive efficiency and quality level with simultaneous reduction of costs. As it was shown in this paper, implementation success is coincident with senior management’s active role in setting the main goals for implementation, assuring that suitable methods and tools are used, allocating resources appropriately and enabling communication within the company

Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described