Global description of action-angle duality for a Poisson-Lie deformation of the trigonometric BCn\mathrm{BC}_n Sutherland system

Integrable many-body systems of Ruijsenaars--Schneider--van Diejen type displaying action-angle duality are derived by Hamiltonian reduction of the Heisenberg double of the Poisson-Lie group $\mathrm{SU}(2n)$. New global models of the reduced phase space are described, revealing non-trivial features of the two systems in duality with one another. For example, after establishing that the symplectic vector space $\mathbb{C}^n\simeq\mathbb{R}^{2n}$ underlies both global models, it is seen that for both systems the action variables generate the standard torus action on $\mathbb{C}^n$, and the fixed point of this action corresponds to the unique equilibrium positions of the pertinent systems. The systems in duality are found to be non-degenerate in the sense that the functional dimension of the Poisson algebra of their conserved quantities is equal to half the dimension of the phase space. The dual of the deformed Sutherland system is shown to be a limiting case of a van Diejen system.Comment: 39 pages, some stylistic changes and typos removed in v

ENDOGENOUS PROTECTION IN THE MEXICAN CORN AND SORGHUM MARKET

Trade relations between the United States (U.S) and Mexico are increasingly interrelated and important ever since the ratification of NAFTA in 1994. With the advent of NAFTA, tariffs on many agricultural products were lowered or are in the process of being lowered. Mexico implements a tariff-rate quota for corn which is to be phased out by 2009. This quota is divided among the various Mexican corn importers with "cupos", which are import permits. Import permits are administrative trade barriers that can be defined as any obstacle that appears and disappears as market conditions change. It is widely recognized in the literature that administrative trade barriers create numerous obstacles to the international exchange of agricultural products. In this paper a conceptual structural model of international marketing margins and trade uncertainty is specified that links the private market to political factors influencing administrative trade barriers. In doing so, this systematically links trade models specified by Gallagher (1998) and others, which characterize private markets under uncertainty but ignore direct influences from political markets, to work by Trefler (1993) and others, which focus on endogenous trade protection. The general objective of this study is to increase the understanding of the impact of institutional aspects on agricultural trade. The specific objectives are to quantify the impact of import permits for white and yellow corn on international marketing margins between the U.S. and Mexico for white corn, yellow corn, and sorghum, as well as approximate the impact of changing political market variables on total welfare. Conceptually understanding the underlying processes and estimating empirical relationships for these objectives leads to important insights into the effect of the Mexican government's policy of allocating corn import permits have on the price and quantity of corn and sorghum. A complete structural model of white corn, yellow corn, and sorghum is specified, wherein import demand equations are generalized to incorporate simultaneous variables of trade protection (Trefler 1993) and then estimated with a simultaneous tobit estimator. The results provide interesting insights into the way that import permits work in Mexico. Interestingly, generalizing the import demand equations to account for trade protection dramatically alters international marketing margins for white corn and sorghum in a manner consistent with findings in Trefler. However, yellow corn appears unaffected. Further, political and industry interests driving trade protection in Mexico are found to influence import demand. For example, political pressure from corn and sorghum producers has a negative affect on the import demand for corn and sorghum. These results are consistent with other conjectures and findings in public choice analysis, which indicate that increases in import penetration will increase lobbying efforts from domestic firms to decrease imports. These results indicate that as grain producers lobby for a decrease in import permit allocations the import demand for these grains decreases, meaning that they have succeeded in their efforts to reduce import competition. In all, these insights provide the means to better understand how subtle trade barriers affect the trade flow between countries.Crop Production/Industries,

Exploring modality switching effects in negated sentences: further evidence for grounded representations

Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing “not”). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation

Political allocation of U.S. agriculture disaster payments in the 1990s

Legislation passed during the 1990s attempted to move U.S. agriculture disaster relief to a more market oriented process. The failure of this legislation has been attributed to the political system behind agricultural disaster relief. This paper explores the impact of political influence on the allocation of U.S. direct agriculture disaster payments. The results reveal that disaster payments are not based solely on need, but are higher in those states represented by public officials key to the allocation of relief. The effectiveness of legislation aimed at promoting more efficient disaster payments systems, such as crop insurance, over direct cash payments is also examined.Agriculture ; Disaster relief

Trigonometric real form of the spin RS model of Krichever and Zabrodin

We investigate the trigonometric real form of the spin Ruijsenaars-Schneider system introduced, at the level of equations of motion, by Krichever and Zabrodin in 1995. This pioneering work and all earlier studies of the Hamiltonian interpretation of the system were performed in complex holomorphic settings; understanding the real forms is a non-trivial problem. We explain that the trigonometric real form emerges from Hamiltonian reduction of an obviously integrable 'free' system carried by a spin extension of the Heisenberg double of the ${\rm U}(n)$ Poisson-Lie group. The Poisson structure on the unreduced real phase space ${\rm GL}(n,\mathbb{C}) \times \mathbb{C}^{nd}$ is the direct product of that of the Heisenberg double and $d\geq 2$ copies of a ${\rm U}(n)$ covariant Poisson structure on $\mathbb{C}^n \simeq \mathbb{R}^{2n}$ found by Zakrzewski, also in 1995. We reduce by fixing a group valued moment map to a multiple of the identity, and analyze the resulting reduced system in detail. In particular, we derive on the reduced phase space the Hamiltonian structure of the trigonometric spin Ruijsenaars-Schneider system and we prove its degenerate integrability.Comment: 52 pages, 1 figure. v2: typos removed, final versio

How to reach a few percent level in determining the Lense-Thirring effect?

In this paper we discuss and compare a node-only LAGEOS-LAGEOS II combination and a node-only LAGEOS-LAGEOS II-Ajisai-Jason1 combination for the determination of the Lense-Thirring effect. The new combined EIGEN-CG01C Earth gravity model has been adopted. The second combination cancels the first three even zonal harmonics along with their secular variations but introduces the non-gravitational perturbations of Jason1. The first combination is less sensitive to the non-conservative forces but is sensitive to the secular variations of the uncancelled even zonal harmonics of low degree J4 and J6 whose impact grows linearly in time.Comment: Latex2e, 22 pag. 1 table, 2 figures, 45 references. Changes in the Abstract, Introduction and Conclusions. Discussion on the non-gravitational perturbations on Ajisai and on the impact of the secular rates of the even zonal harmonics added. EIGEN-CG01C CHAMP+GRACE+terrestrial gravimetry/altimetry Earth gravity model used. Reference adde

Photoemission Evidence for a Remnant Fermi Surface and d-Wave-Like Dispersion in Insulating Ca2CuO2Cl2

An angle resolved photoemission study on Ca2CuO2Cl2, a parent compound of high Tc superconductors is reported. Analysis of the electron occupation probability, n(k) from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the |cos(kxa)-cos(kya)| form along this remnant Fermi surface. Together with the data from Dy doped Bi2Sr2CaCu2O(8 + delta) these results suggest that this d-wave like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime.Comment: 9 pages, including 7 figures. Published in Science, one figure correcte

Modality switching and negation: ERP evidence for modality-specific simulations during negation processing

The Perceptual Symbol System Theory of cognition (Barsalou, 1999) suggests that modality-specific simulations underlie representation of concepts. This is evidenced by processing costs for switching modalities. That is, participants are slower to verify a property in the auditory modality (e.g., BLENDER-loud) after verifying a property in a different modality (e.g., CRANBERRIES-tart) and faster when verifying a property in the same modality (e.g., LEAVES-rustling). The modality switch cost has also been shown to lead to a modulation of the N400 event-related potential (ERP) (Collins, Pecher, Zeelenberg & Coulson, 2011 using a property verification task; Hald, Marshall, Janssen & Garnham, 2011 using a sentence verification task). In a separate line of research, ERP studies have indicated that without a discourse context, negated sentences are more difficult to process than affirmative sentences, leading to a different N400 pattern for negative sentences than for affirmative sentences (e.g., Fischler, Bloom, Childers, Roucos, & Perry, 1983.) Unlike affirmative sentences, sentences containing negation show a larger N400 for correct, semantically coherent single sentences (i.e., factually true sentences) than for semantically incorrect sentences (i.e., false sentences). However, Nieuwland and Kuperberg (2008,) found that the pragmatics of the sentence can change this N400 pattern to one closer to affirmative sentences. The goal of the current study was to explore whether the processing of negation could be aided by modality matching information. Other evidence suggests that comprehenders create a simulation of negative sentences (Kaup, Yaxley, Madden, Zwaan, & Lüdtke, 2007), but it is unclear whether modality matching information could modulate the processing cost of negation. Essentially, can modality matching information as reported by Collins et al., (2011) and Hald et al., (2011) lead to a modulation of the N400 for true negated sentences similar to that seen when discourse pragmatics supports negation? Furthermore, we were interested in whether the modality switch effect would lead to a similar pattern in the ERPs as that found with affirmative sentences (Collins et al., 2011 & Hald et al., 2011). Using a within-subjects design we used 160 pairs of experimental pairs which were either of the same or of a different modality. All experimental items were either visual or tactile modality and were drawn from existing sets of materials (Pecher, et al., 2003; Van Dantzig, et al., 2008). For example, a different modality pair was “A light bulb is very hot” followed by “Rice isn’t black” versus a same visual modality pair “A giraffe is spotted” followed by “Rice isn’t black”. We predicted that the underlined word is where a modulation in the N400 may be seen. Additionally, we explored veracity by making half of the experimental target sentences false (“Rice isn’t white”). Participants were asked to judge whether each sentence was typically true or false. Our initial results indicate a modulation in the ERP based on both modality and veracity. For true (“Rice isn’t black”) and false target statements (“Rice isn’t white”) different modality pairs elicit a larger frontal-central N400 like effect compared to same modality pairs (Figure 1), replicating Hald et al., (2011). When comparing true versus false, the different modality pairs elicit a large posterior N400 for true compared to false sentences (replicating the effect for negated sentences, i.e., Fischler et al., 1983). However for same modality pairs there is a reduction in the N400 to true statements; no difference is seen between true and false statements in the ERP (Figure 2). These results replicate and extend previous ERP findings using the modality switch paradigm. The evidence suggests that not only do modality-specific simulations occur but they can even aid the processing of negation