COVID-19, stock market and sectoral contagion in US: a time-frequency analysis

We assess the conditional relationship in the time-frequency domain between the return on S&P 500 and confirmed cases and deaths by COVID-19 in Hubei, China, countries with record deaths and the world, for the period from January 29 to June 30, 2020. Methodologically, we follow Aguiar-Conraria et al. (2018), by using partial coherencies, phase-difference diagrams, and gains. We also perform a parametric test for Granger-causality in quantiles developed by Troster (2018). We find that short-term cycles of deaths in Italy in the first days of March, and soon afterwards, cycles of deaths in the world are able to lead out-of-phase US stock market. We find that low frequency cycles of the US market index in the first half of April are useful to anticipate in an anti-phasic way the cycles of deaths in the US. We also explore sectoral contagion, based on dissimilarities, Granger causality and partial coherencies between S&P sector indices. Our findings, such as the strategic role of the energy sector, which first reacted to the pandemic, or the evidence about predictability of the Telecom cycles, are useful to tell the history of the pass-through of this recent health crises across the sectors of the US economy.     

Neutrality in arrow and other impossibility theorems

Summary. Although not assumed explicitly, we show that neutrality plays an important role in Arrow and other impossibility theorems. Applying it to pivotal voters we produce direct proofs of classical impossibility theorems, including Arrow's, as well as extend some of these theorems. We further explore the role of neutrality showing that it is equivalent to Pareto or reverse Pareto, and to effective dictatorship for non-null social welfare functions satisfying the principle of independence of irrelevant alternatives. It is also equivalent to Wilson's Citizens' Sovereignty--which is related to the intuition that symmetry over alternatives makes social preference depend only on citizens' preferences. We show that some of these results are more fundamental than others in that they extend both to infinite societies and to considerably smaller domains of preferences. Finally, as an application of Arrow's theorem, we provide a simple proof of the Gibbard-Satterthwaite theorem.Received: 13 April 2000, Revised: 6 December 2002, JEL Classification Numbers: D71, C70.I thank Salvador Barberá, Luis Corchón, Cesar Martinelli, Eric Maskin, Tomas Sjöström, Ricard Torres, José Pedro Ubeda, and an anonymous referee for feedback. The proofs of Arrow's theorem and two Wilson's theorems come from a note I wrote in 1987 at Universitat Autónoma de Barcelona (Ubeda [16]). In 1996 Geanakoplos [7] wrote a proof of Arrow's theorem similar but not identical to mine. All work in this paper is independent of his.     

概念整合理论对诗性隐喻的认知阐释

诗歌是一种独特的语言形式,充满了隐喻,因而它被称为"隐喻性语言"。一个隐喻可以同时在不同的图标层面解释,从最抽象的认知方面到最具体的感官认知,将时空的维度组织成"认知域"。本文从认知的新视点出发,用概念合成理论来解读狄金森和弗罗斯特诗歌的诗性隐喻,以期更好地欣赏其诗歌。     

Does the nature of airport terminal service activities matter? Processing and non-processing service quality,passenger affective image and satisfaction

The surge in air transport demand and the increasingly competitive and volatile market dynamics due to airline deregulation are rapidly transforming airports’ character into multi-service firms and destinations. As a result, service performance measurement of significant systems and their consequent impact on airport users are crucial in creating better airport service design, operation and management for sustainable competitive advantage. The present study 1) assesses the applicability of the Airport Indicators of Passenger Experience (AIPEX) model on Shanghai Pudong International Airport (PVG), and 2) tests a theoretical model that explores the direct and indirect relationships among airport service quality, passenger affective image and satisfaction, as well as the moderating mechanism of passenger type (travel purpose) in these associations. The results indicate that, the AIPEX model fits the PVG context for airport service performance assessment. Also, the theoretical model suggests robust direct associations among processing/non-processing domains and passenger satisfaction, as well as the processing domain and passenger affective image, except non-processing domain and passenger affective image relation. Moreover, significant mediating and moderating effects of passenger affective image and travel purpose on the significant positive direct associations are found. Further, implications for theory and practice are discussed.     

基于系统理论的水资源统一管理范畴探讨

水资源可持续发展战略已经成为各国社会、经济和环境发展的共同准则。我国也提出新时期治水思路是水资源的可持续利用,而这一目标的实现,在一定程度上取决于水资源的统一管理及其管理体制。文章运用系统理论,从水资源系统的整体性、层次性、目的性、动态性和开放性、自然属性和社会属性等特性出发,分析了水资源统一管理的必要性,提出基于系统理论的水资源统一管理的管理范畴模型,并结合深圳市和重庆市水务一体化改革的经验进行了实践分析。     

Competitive trade models and real world features

Competitive small-dimension international trade models perform well in comparing free (or restrictive) trade with autarky, especially in emphasizing that consumption patterns can differ from production patterns and that production becomes highly concentrated while consumption patterns are expanded. Variations on these small-dimensional models can usefully show how with trade production patterns may nonetheless be more diverse and a country’s labor force become more heterogeneous in its skills. The paper illustrates how the Middle Products framework can be reinterpreted to support variety in production and in labor skills.      

循环前缀在OFDM系统中的应用

本文详细论述了OFDM系统中循环前缀在削弱符号间干扰（ISI）、载波间干扰（ICI）以及在实现时频同步中的应用。在OFDM符号间插入循环前缀，可以减小ISI和ICI，并为实时时频偏移估计提供足够信息，使得系统同步结构简单且工作高效。     

基于时频分析的裂纹转子碰摩故障特征研究

为研究转子系统耦合故障特性,采用有限元方法建立了含有横向裂纹、转静碰摩的非线性转子动力学模型。首先研究了不同转速下裂纹、碰摩单一故障下转子系统的振动响应,其次研究了两种故障耦合情况下系统的振动响应特征。采用波形图、FFT谱图、瞬时频率和Hilbert-Huang时频谱(HHS)相结合的方法对故障转子振动信号进行了分析。分析结果表明:运用多种时频分析相结合的方法可以较为全面地了解转子的故障特征,裂纹转子在1/5、1/3临界转速时会发生较为明显的5X、3X谐波,且裂纹的产生会导致响应幅值增大,从而引起更为严重的碰摩。      

Non-manipulable domains for the Borda count

Summary. We characterize the preference domains on which the Borda count satisfies Arrows independence of irrelevant alternatives condition. Under a weak richness condition, these domains are obtained by fixing one preference ordering and including all its cyclic permutations (Condorcet cycles). We then ask on which domains the Borda count is non-manipulable. It turns out that it is non-manipulable on a broader class of domains when combined with appropriately chosen tie-breaking rules. On the other hand, we also prove that the rich domains on which the Borda count is non-manipulable for all possible tie-breaking rules are again the cyclic permutation domains.Received: 24 November 2003, Revised: 12 December 2004, JEL Classification Numbers: D71. Correspondence to: Clemens PuppeThe third author gratefully acknowledges the financial support from the Deutsche Forschungsgemeinschaft (DFG), Graduiertenkolleg 629 at the University of Bonn and from the Hungarian Scientific Research Fund (OTKA F 043496).     

Revisiting global economic activity and crude oil prices: A wavelet analysis

Based on the wavelet analysis approach, this paper firstly examines the dynamic relationship between global economic activity (proxied by the Kilian economic index) and crude oil prices in both time- and frequency-domains. Our empirical results demonstrate significant correlation between crude oil prices and global economic activity at high frequencies (in the short run) during the entire sample period; however, the co-movement between the two at low frequencies (in the long run) is weaker and exists only during certain proportions of the sample period. We also document evidence that global economic activity and oil price are positively correlated, with dynamic lead-lag relationships across time. Our findings are robust to alternative choices of oil price indexes and controlling for other confounding factors such as geopolitical risk, armed conflicts, economic policy uncertainty and equity market uncertainty. The current study provides valuable implications for oil market investors based on the information of global economic situation and its dynamic relationships with oil prices.