Raman fingerprint of semi-metal WTe2 from bulk to monolayer

Tungsten ditelluride (WTe2), a layered transition-metal dichalcogenide (TMD), has recently demonstrated an extremely large magnetoresistance effect, which is unique among TMDs. This fascinating feature seems to be correlated with its special electronic structure. Here, we report the observation of 6 Raman peaks corresponding to the A_2^4, A_1^9, A_1^8, A_1^6, A_1^5 and A_1^2 phonons, from the 33 Raman-active modes predicted for WTe2. This provides direct evidence to distinguish the space group of WTe2 from that of other TMDs. Moreover, the Raman evolution of WTe2 from bulk to monolayer is clearly revealed. It is interesting to find that the A_2^4 mode, centered at ~109.8 cm-1, is forbidden in a monolayer, which may be attributable to the transition of the point group from C2v (bulk) to C2h (monolayer). Our work characterizes all observed Raman peaks in the bulk and few-layer samples and provides a route to study the physical properties of two-dimensional WTe2.Comment: 19 pages, 4 figures and 2 table

Endowment structures, industrial dynamics, and economic growth

Economic Theory&Research,Political Economy,Economic Growth,Debt Markets,Emerging Markets

Marshallian externality, industrial upgrading, and industrial policies

A growth model with multiple industries is developed to study how industries evolve as capital accumulates endogenously when each industry exhibits Marshallian externality (increasing returns to scale) and to explain why industrial policies sometimes succeed but sometimes fail. The authors show that, in the long run, the laissez-faire market equilibrium is Pareto optimal when the time discount rate is sufficiently small or sufficiently large. When the time discount rate is moderate, there exist multiple dynamic market equilibria with diverse patterns of industrial development. To achieve Pareto efficiency, it would require the government to identify the industry target consistent with the comparative advantage and to coordinate in a timely manner, possibly for multiple times. However, industrial policies may make people worse off than in the market equilibrium if the government picks an industry that deviates from the comparative advantage of the economy.Water and Industry,Economic Theory&Research,Industrial Management,Industrial Economics,Common Property Resource Development

Healthsouth Corporation: The First Case Against A Company Under The Sarbanes-Oxley Act

HealthSouth Corporation, one of the nation’s largest healthcare providers, was the first company charged under the provisions of the Sarbanes-Oxley Act.  HealthSouth’s CEO, Richard Scrushy, and 16 of its executives were indicted for allegedly using a sophisticated scheme to overstate the company’s earnings by as much as $2.7 billion between 1986 and 2002.  Fifteen of the sixteen indicted executives pleaded guilty and another was convicted by jurors.  After five months of court hearing, Scrushy was acquitted of all criminal charges.  However, he remains a defendant in 40 cases filed by former HealthSouth investors and creditors.   This case is based on court materials and other publicly available information and has been used in several undergraduate and MBA courses.  The case and the accompanying teaching notes have proven to be an effective tool in teaching students the Sarbanes-Oxley Act and in helping students become more ethically conscious

Improving Conversational Passage Re-ranking with View Ensemble

This paper presents ConvRerank, a conversational passage re-ranker that employs a newly developed pseudo-labeling approach. Our proposed view-ensemble method enhances the quality of pseudo-labeled data, thus improving the fine-tuning of ConvRerank. Our experimental evaluation on benchmark datasets shows that combining ConvRerank with a conversational dense retriever in a cascaded manner achieves a good balance between effectiveness and efficiency. Compared to baseline methods, our cascaded pipeline demonstrates lower latency and higher top-ranking effectiveness. Furthermore, the in-depth analysis confirms the potential of our approach to improving the effectiveness of conversational search.Comment: SIGIR 202