How far do shocks move across borders?: Examining volatility transmission in major agricultural futures markets

This paper examines the level of interdependence and volatility transmission across major exchanges of maize, wheat, and soybeans in the United States, Europe, and Asia. We follow a multivariate GARCH approach to explore in detail and under different specifications the dynamics and cross-dynamics of volatility in agricultural futures markets. We account for the potential bias that may arise when considering exchanges with different closing times. The period of analysis is 2004–2009 for maize and soybeans and 2005–2009 for wheat. The results indicate that there is a strong correlation among international markets. In particular, we find both own- and cross-volatility spillovers and dependence between most of the exchanges. There is also higher interaction between the United States (Chicago) and both Europe and Asia than within the latter. The results further show the major role Chicago plays in terms of spillover effects over the other markets, particularly for maize and wheat. For soybeans, both China and Japan also exhibit important cross-volatility spillovers. Finally, the level of interdependence between exchanges has not necessarily increased in recent years for all commodities. From a policy perspective, these findings suggest that any potential regulatory scheme to address (excessive) price volatility in agricultural exchanges should be coordinated across markets; localized regulation will have limited effects given the high level of interrelation between markets.volatility transmission, agricultural commodities, futures markets, multivariate GARCH,

Separating between unobserved consumer types: evidence from airlines

We propose an alternative approach to identify unobserved consumer types and assess whether firms price discriminate. Unlike other screening schemes that rely on quantity discounts or product differentiation, in our finite mixture structure individuals have unit demands and the product is homogeneous. We implement the model using an original U.S. airlines data set. The results support the existence of two demand types. The high-type “business” traveler is less price sensitive, has a higher valuation, and pays a higher price than the low type “tourist.” The proportion of high types also increases as the departure date nears. (JEL C23, L93, R41

Propagation of generalized vector Helmholtz-Gauss beams through paraxial optical systems

We introduce the generalized vector Helmholtz-Gauss (gVHzG) beams that constitute a general family of localized beam solutions of the Maxwell equations in the paraxial domain. The propagation of the electromagnetic components through axisymmetric ABCD optical systems is expressed elegantly in a coordinate-free and closed-form expression that is fully characterized by the transformation of two independent complex beam parameters. The transverse mathematical structure of the gVHzG beams is form-invariant under paraxial transformations. Any paraxial beam with the same waist size and transverse spatial frequency can be expressed as a superposition of gVHzG beams with the appropriate weight factors. This formalism can be straightforwardly applied to propagate vector Bessel-Gauss, Mathieu-Gauss, and Parabolic-Gauss beams, among others

Making friends with your neighbors? Agglomeration and tacit collusion in the lodging industry

Agglomeration is a location pattern frequently observed in service industries such as hotels. This paper empirically examines if agglomeration facilitates tacit collusion in the lodging industry using a quarterly dataset of hotels that operated in rural areas across Texas between 2003 and 2005. We jointly model a price and occupancy rate equation under a switching regression model to endogenously identify a collusive and non-collusive regime. The estimation results indicate that clustered hotels have a higher probability of being in the potential collusive regime than isolated properties in the same town. The identification of a collusive regime is also consistent with other factors considered to affect the sustainability of collusion like cluster size, seasonality and firm size, and the results are robust to alternative cluster definitions.

Sistema de tracking para arrays de banda estrecha usando SVD

Los métodos de superresolución utilizados actualmente en detección de ángulo de llegada se derivan o están soportados de alguna manera en la descomposición en valores singulares o en la descomposición en las componentes principales de la matriz de covarianza o correlación de Ios sucesivos snapshots tornados de la apertura. La necesidad de disponer de Ios subespacios de señal o de ruido en cada snapshot, plantea el problema de un método que permita la actualización snapshot a snapshot de Ios autovectores. Este objetivo del trabajo se ha conseguido explotando el hecho de que la actualización de la matriz es, a cada snapshot, de rango uno. Gracias a ello, la descomposición canónica de la matriz de covarianza es inmediatamente actualizada usando un algoritmo de alta eficiencia computacional, sin necesidad de recalcular la SVD de la nueva matriz de covarianza.Peer ReviewedPostprint (published version

A decision support system for the optimal design of base-motion isolators

Transient analysis of large structural systems is a computationally demanding process, which in the past has prevented dynamic redesign and optimization. Large structures, such as buildings or ships, subjected to random base motions use isolators to minimize strain energies, which may cause damage or structural failure. This research focuses on the optimization of isolator parameters in order for structural systems to withstand potentially catastrophic transient vibrations. Many non-linear hysteretic, viscoelastic, and sliding friction isolators were numerically modeled using the scientific programming language, MATLAB. The existing programs used to solve the Voltera integral formulation for Transient Structural Synthesis (TSS) and the Recursive Block-by-Block (RBB) algorithm were investigated and enhanced to yield greater accuracy and increased computational speed. The final product is a user-friendly Decision Support System (DSS) for use with both civil and military applications. Based on different types of base motions and the inherent dynamics of the structure, this DSS is capable of optimizing isolator parameters to meet a user specific objective.http://archive.org/details/adecisionsupport109456311Lieutenant, United States NavyApproved for public release; distribution is unlimited

Disentangling meaning in the brain: Left temporal involvement in agreement processing

Published online 18 November 2016Sentence comprehension is successfully accomplished by means of a form-to-meaning mapping procedure that relies on the extraction of morphosyntactic information from the input and its mapping to higher-level semantic–discourse representations. In this study, we sought to determine whether neuroanatomically distinct brain regions are involved in the processing of different types of information contained in the propositional meaning of a sentence, namely person and number. While person information indexes the role that an individual has in discourse (i.e., the speaker, the addressee or the entity being talked about by speaker and addressee), number indicates its cardinality (i.e., a single entity vs a multitude of entities). An event-related functional magnetic resonance imaging (fMRI) experiment was run using agreement-Correct and Person- and Number-violated sentences in Spanish, to disentangle the processing mechanisms and neural substrates associated with the building of discourse and cardinality representations. The contrast between Person and Number Violations showed qualitative and quantitative differences. A greater response for person compared to number was found in the left middle temporal gyrus (LMTG). However, critically, a posterior-to-anterior functional gradient emerged within this region. While the posterior portion of the LMTG was sensitive to both Person and Number Violations, the anterior portion of this region showed selective response for Person Violations. These results confirm that the comprehension of the propositional meaning of a sentence results from a composite, feature-sensitive mechanism of form-to-meaning mapping in which the nodes of the language network are differentially involved.BCBL acknowledges funding from Ayuda Centro de Excelencia Severo Ochoa SEV-2015-0490. S.M. acknowledges funding from the Gipuzkoako Foru Aldundia Fellowship Program and from grant PI_2014_38 from the Basque Government. N.M. was funded by grant PSI2012- 32350 and PSI2015-65694-P from the Spanish Ministry of Economy and Competitiveness. M.C was funded by grant PSI2012-31448 from the Spanish Ministry of Science and Innovation and ERC-2011-ADG-295362 from the European Research Council

Nonlinear Pricing Strategies and Market Concentration in the Airline Industry

This dissertation investigates the effect of market concentration on nonlinear pricing strategies in the airline industry. The study develops a theoretical nonlinear pricing model with both discrete product and consumer types to derive testable implications about the impact of market concentration on the structure of relative prices within a menu of prices. The analysis then uses a unique, airline ticket level data set to test the model predictions. The data set consists of a representative sample of airline tickets purchased between June and December 2004 from one major Computer Reservation System (CRS), for travel in the fourth quarter of the same year. The study restricts attention to 246 domestic routes in the United States, resulting in 878,169 tickets. This unique data set allows us to examine the effect of market structure conditions on relative prices within a menu of fare types with restrictive ticket characteristics. The analysis also contributes to the understanding of how the level of competition in a market affects the dispersion of airline prices. The results indicate that market concentration differentially impacts high versus low priced fares, as predicted by the theoretical model. More specifically, there is a decrease in the ratio of high- to low-quality fares as markets become more concentrated, after controlling for numerous factors that may affect prices through costs and market characteristics. The ratio of medium- to low-quality fares, however, increases with less competition. From a welfare perspective, it is interesting to observe that not all travelers are affected in the same way by a decrease in the level of competition. Business travelers, who purchase high priced fares, end up paying relatively lower prices in more concentrated markets while leisure travelers pay more

Spatial Mapping and Modeling of Reported Dengue Incidences in Luzon

Dengue, the most rapidly spreading mosquito-borne viral infection, has significantly spread worldwide in recent decades - flourishing both in affluent and impoverished locations of tropical and subtropical countries. In 2012, the Philippines ranked fourth out of the ten Association of the Southeast Asian Nations (ASEAN) countries in having the highest number of dengue cases. The following study intends to analyze the spatial distribution of dengue incidences across all Luzon provinces in 2018. It aims to determine significant correlates that affect dengue incidences, map the incidence rate of dengue cases, and explore the clustering of recorded dengue cases. Poisson and Negative Binomial (NB) regression analyses and Multiple Linear Regression Models (MLRM) were applied to determine the significant correlations affecting dengue incidence rates. Simultaneously, spatial mapping was utilized to visualize and detect clustering in the provinces through dengue count, incidence ratios, and standard incidence ratios (SIR). MLRM and NB showed that rainfall and poverty incidence are significant correlates of dengue counts and incidence, and Nueva Ecija and Tarlac were observed to be provinces with distinct dengue count and SIR greater than 1, as well as provinces found in clusters. With the provided results, health organizations can provide health programs and allocate more funds in areas with SIR greater than 1 to prevent dengue spreading