Towards a methodology for measuring the true degree of efficiency in a speculative market

Betting markets have drawn much attention in the economics, finance and operational research literature because they provide a valuable window on the manner in which individuals use information in wider financial markets. One question that has received particular attention is to what extent individuals discount information in market prices. The predominant approach to explore this issue involves predictive modeling to forecast market outcomes and examining empirically whether abnormal returns can be made by employing these forecasts. It is argued here that present practices to assess such forecasting models, including the use of point estimates and information, which would not be available in practice (at the forecasting stage) and failing to update forecasting models with information from the recent past, may give rise to misleading conclusions regarding a market's informational efficiency. Hypotheses are developed to conceptualize these views and are tested by means of extensive empirical experimentation using real-world data from the Hong Kong horserace betting market. Our study identifies several sources of bias and confirms that current practices may not be relied upon. A more appropriate modeling procedure for assessing the true degree of market efficiency is then proposed.     

Attenuated total reflectance powder cell for infrared analysis of hygroscopic samples

An attenuated total reflectance (ATR) sample cell has been designed, manufactured and subsequently used for the mid-infrared analysis of hygroscopic samples. This sample cell was installed as a simple drop-in replacement for the cell supplied with our commercially available Harrick Mvp-Pro FTIR–ATR accessory. Calcium chloride, a well-known desiccant that has a propensity to absorb water into its crystal lattice, was selected as non-infrared active substrate to accentuate the efficacy of the cell in preserving the anhydrous state of the sample by straightforward monitoring of the water bands. In contrast, mid-infrared spectra are presented that qualitatively demonstrate the rapid rate at which atmospheric moisture is incorporated into the anhydrous sample when analyzed using the conventional ATR cell assembly.     

Périodicité des fractions continues dans un corps de fonctions hyperelliptiques

Sans résumé     

Multi-Conjugate Adaptive Optics for ELTs: constraints and limitations

We present how enlarging the size of a telescope from the current 10 meter telescope to the future 100 meter Extremely Large Telescopes increases the complexity of a classical or multiconjugate adaptive optics instrument. We point out elements or parameters of the system for which it is critical to propose new ideas as solutions and we study the effect of the increase of the diameter on the point spread function of an MCAO and a Ground Layer AO system. To cite this article: R. Ragazzoni et al., C. R. Physique 6 (2005).     

Une application des nombres de Pisot à l'algorithme de Jacobi-Perron

SinceO. Perron introduced in 1907 Jacobi-Perron algorithm, which is the simplest generalization of continued fractions to finite sets of real numbers, the main question of characterising the periodicity is still open. The usual conjecture is that the development of any basis of a real number field by this algorithm is periodic. But we only know some infinite families for which this is true. In this paper we prove that for any real number field there exists a basis for which we have periodicity.     

High-resolution Fourier spectroscopy of 14N2 and 15N2 infrared emission spectrum: Analysis of the B′3Σu−-B3Πg system

The rotational analysis of some bands of the B′³Σ_u^?-B³Π_g system of nitrogen (¹⁴N₂ and ¹⁵N₂) excited in a microwave discharge and recorded under high resolution with a Fourier transform interferometer allowed the determination of molecular constants for the v = 0, 1, 2 levels in the B′³Σ_u^? state. Main equilibrium constants of the B′³Σ_u^? state for ¹⁴N₂ and ¹⁵N₂ are (in cm^?1) T_e = 5789.2178 (relative to B³Π_g (v = 0); ω_e = 1516.6239; ω_ex_e = 11.9721; B_e = 1.473 098; α_B = 0.01 664; ω_eⁱ = 1465.3549; ω_ex_eⁱ = 11.1783; B_eⁱ = 1.375 209; α_Bⁱ = 0.01 505.     

Etude de la reactivite de l'ion azoture vis á vis de cations heterocycliques-I: Inhibition de la formation d'azides covalents par un complexe pyrylium-azoture constituant un “cul de sac” reactionnel. mise en evidence expérimentale

The reactivity of azide anion with pyrylium and thiopyrylium substituted cations depends on the substitution of the heterocyclic cation. Only sterically hindered pyrylium or thiopyrylium cations lead to the formation of covalent azides. On the other hand, pyrylium or thiopyrylium cations which are not sterically hindered give a donor acceptor complex. The formation of this complex constitutes a dead-end reaction on the normal pathway to covalent azides. This apparently unusual behaviour cannot be rationalized with simple concepts such as charge density or frontier orbital coefficients.