Whale-watching and Herring Fishing: Joint or Independent Production?

The effects of "localized depletion" of a pelagic fishery (herring) on a non-extractive marine activity (tourism) are investigated. Proponents of the localized depletion theory claim that intense fishing effort can lead to areas that are unsuitable for predators like tuna, groundfish, and whales. This leads to poor outcomes for the fishing and whale-watching industries. However, there has been no consensus in the scientific community about the existence of this phenomenon. Localized depletion would be consistent with an economic theory of joint production, in which nearshore herring stocks are an input in production of both herring and whale-watching trips. A unique dataset of daily whale-watching outcomes is combined with fishing effort and oceanographic data. This dataset is used to test the hypothesis that intensive fishing effort increases the search time of whale-watching companies. Our results suggest that while fishing has a statistically significant impact on sightings, this magnitude of this effect is fairly small. Sightings seem to be determined mostly by large scale oceanographic processes. These results should be of interest to policymakers in determining future fishing regulations.whales, fishing, panel data, search, Ecosystem Based Management, Resource /Energy Economics and Policy, Q57, Q26, Q22,

Consolidation as a Regulatory Compliance Strategy: Small Drinking Water Systems and the Safe Drinking Water Act

Despite extensive research and policy initiatives to increase the technical, financial, and managerial capacity of small drinking water systems, there has been little research focusing on understanding how consolidation can increase the overall capacity of the drinking water industry. Consolidation of water systems may be a mechanism that increases regulatory compliance by removing poorly performing systems from the industry and replacing inefficient management and/or capital. The US drinking water system is highly fragmented, with over 50,000 Community Water Systems (CWSs), of which the vast majority are classified as "small" by the US Environmental Protection Agency (EPA). A discrete choice model is employed to determine the characteristics shared by small water systems that are acquired. On average, these acquired firms are small, have frequent drinking water violations, are privately-owned, and purchase their water from another system. These results suggest that consolidation may have an important role to play in increasing overall industry compliance with the Safe Drinking Water Act (SDWA).Community Water System, Drinking Water, Merger, Consolidation, Resource /Energy Economics and Policy, Q25, Q53,

Click-aware purchase prediction with push at the top

Eliciting user preferences from purchase records for performing purchase prediction is challenging because negative feedback is not explicitly observed, and because treating all non-purchased items equally as negative feedback is unrealistic. Therefore, in this study, we present a framework that leverages the past click records of users to compensate for the missing user-item interactions of purchase records, i.e., non-purchased items. We begin by formulating various model assumptions, each one assuming a different order of user preferences among purchased, clicked-but-not-purchased, and non-clicked items, to study the usefulness of leveraging click records. We implement the model assumptions using the Bayesian personalized ranking model, which maximizes the area under the curve for bipartite ranking. However, we argue that using click records for bipartite ranking needs a meticulously designed model because of the relative unreliableness of click records compared with that of purchase records. Therefore, we ultimately propose a novel learning-to-rank method, called P3Stop, for performing purchase prediction. The proposed model is customized to be robust to relatively unreliable click records by particularly focusing on the accuracy of top-ranked items. Experimental results on two real-world e-commerce datasets demonstrate that P3STop considerably outperforms the state-of-the-art implicit-feedback-based recommendation methods, especially for top-ranked items.Comment: For the final published journal version, see https://doi.org/10.1016/j.ins.2020.02.06

Flow-based Intrinsic Curiosity Module

In this paper, we focus on a prediction-based novelty estimation strategy upon the deep reinforcement learning (DRL) framework, and present a flow-based intrinsic curiosity module (FICM) to exploit the prediction errors from optical flow estimation as exploration bonuses. We propose the concept of leveraging motion features captured between consecutive observations to evaluate the novelty of observations in an environment. FICM encourages a DRL agent to explore observations with unfamiliar motion features, and requires only two consecutive frames to obtain sufficient information when estimating the novelty. We evaluate our method and compare it with a number of existing methods on multiple benchmark environments, including Atari games, Super Mario Bros., and ViZDoom. We demonstrate that FICM is favorable to tasks or environments featuring moving objects, which allow FICM to utilize the motion features between consecutive observations. We further ablatively analyze the encoding efficiency of FICM, and discuss its applicable domains comprehensively.Comment: The SOLE copyright holder is IJCAI (International Joint Conferences on Artificial Intelligence), all rights reserved. The link is provided as follows: https://www.ijcai.org/Proceedings/2020/28

Comment on "Coulomb Instabilities of a Three-Dimensional Higher-Order Topological Insulator"

Based on renormalization-group (RG) calculations, a recent Letter by Zhao et al [Phys. Rev. Lett. 127, 176601 (2021)] claimed that three-dimensional second-order topological insulators (SOTIs) are always unstable to the Coulomb interaction and they will thus undergo topological phase transitions to either topological insulators (TIs) or normal insulators. While the calculations in this paper are correct, the conclusion about the topological phase transition from SOTI to TI is not true. The reason behind this false conclusion lies in that the authors use a wrong criterion to identify the phase transition. In this Comment we would like to remind that, to locate the possible transitions from SOTI to TI, an appropriate quantity is the sign-changing mass gap $m_\textrm{surf}$ for the surface states. By examining its behavior within RG approach, the stability of SOTI against weak Coulomb interactions is demonstrated.Comment: 3 pages, 1 figur