Non-parametric statistical thresholding for sparse magnetoencephalography source reconstructions.

Uncovering brain activity from magnetoencephalography (MEG) data requires solving an ill-posed inverse problem, greatly confounded by noise, interference, and correlated sources. Sparse reconstruction algorithms, such as Champagne, show great promise in that they provide focal brain activations robust to these confounds. In this paper, we address the technical considerations of statistically thresholding brain images obtained from sparse reconstruction algorithms. The source power distribution of sparse algorithms makes this class of algorithms ill-suited to "conventional" techniques. We propose two non-parametric resampling methods hypothesized to be compatible with sparse algorithms. The first adapts the maximal statistic procedure to sparse reconstruction results and the second departs from the maximal statistic, putting forth a less stringent procedure that protects against spurious peaks. Simulated MEG data and three real data sets are utilized to demonstrate the efficacy of the proposed methods. Two sparse algorithms, Champagne and generalized minimum-current estimation (G-MCE), are compared to two non-sparse algorithms, a variant of minimum-norm estimation, sLORETA, and an adaptive beamformer. The results, in general, demonstrate that the already sparse images obtained from Champagne and G-MCE are further thresholded by both proposed statistical thresholding procedures. While non-sparse algorithms are thresholded by the maximal statistic procedure, they are not made sparse. The work presented here is one of the first attempts to address the problem of statistically thresholding sparse reconstructions, and aims to improve upon this already advantageous and powerful class of algorithm

What Lessons for Economic Development Can We Draw from the Champagne Fairs?

The medieval Champagne fairs are widely used to draw lessons about the institutional basis for long-distance impersonal exchange. This paper re-examines the causes of the outstanding success of the Champagne fairs in mediating international trade, the timing and causes of the fairs’ decline, and the institutions for securing property rights and enforcing contracts at the fairs. It finds that contract enforcement at the fairs did not take the form of private-order or corporative mechanisms, but was provided by public institutions. More generally, the success and decline of the Champagne fairs depended crucially on the policies adopted by the public authorities.legal system, medieval Europe, trade, private-order institutions, community responsibility system

______ is Necessary for Interpreting a Proposition

In Natural propositions (2014), Stjernfelt contends that the interpretation of a proposition or dicisign requires the joint action of two kinds of signs. A proposition must contain a sign that conveys a general quality. This function can be served by a similarity-based icon or code-based symbol. In addition, a proposition must situate or apply this general quality, so that the predication can become liable of being true or false. This function is served by an index. Stjernfelt rightly considers the co-localization of these two parts to be a primitive phenomenon. Although this primitive character would seem to bar any further analysis, I endeavor to clarify the degree of proximity sufficient to enable co-localization. Siding with Pietarinen (2014), who argues that the whole issue should not be construed in metric terms, I conclude that one cannot make sense of propositional co-localization without appealing to some form of first-person perspective

Explaining champagne prices in Scandinavia - what is the best predictor?

This paper analyses the retail prices of champagnes sold in the Scandinavian countries. Price data for the champagnes contain nearly 380 observations including a range of quality attributes of each champagne. The empirical part of the analysis reveals that the retail prices of champagne can be fairly well explained by a hedonic price function with a degree of explanation corresponding to approximately 60 per cent. However the ratings by the wine experts, in this case Robert Parker, Wine Spectator and to a lesser extent the French ‘1855 Notation’, do just as well in terms of explaining the retail prices of champagnes. Especially the rating of champagnes by Robert Parker seems to be the most influential concerning the sales prices.Champagne; prices; hedonic price function; Scandinavia

Champagne Bubbles : Isolation and Characterization of amphiphilic macromolecules responsible for the stability of the collar at the Champagne / air interface

International audienceThe effervescence and the stability of the ring of fine bubbles crowning the surface of a champagne glass, the “collar”, constitute one of the hallmarks of Champagne. Defects in the stability of this collar are not well understood and account for a significant proportion of bottle return. This study aims to better understand the surface properties of champagne wine such that the foaming properties can be controlled more effectively. Early studies on Champagne foaming properties using the “Mosalux” measurement of the foam level formed by air flow in champagne through fritted glass pointed to a link between protein concentration and foam level [5] but no satisfactory correlation between protein content and foam stability was established. Later measurements were conducted with either ultra-filtrates or ultra-concentrates [4]. The authors demonstrated that macromolecule concentration was an essential parameter in the foam stability. The stability of bubbles is usually ascribed to the presence of an adsorption layer formed at the gas/liquid interface and its properties [3]. Thus surface properties of Champagne were analysed by ellipsometry and tensiometry. Measurements conducted on base wine, on ultra-filtered base wines and degassed champagne samples showed the presence of an adsorption layer formed at the air/champagne wine interface [6] and that adsorption layer being composed of macromolecules in a 104 to 105 molecular range [7]. Previous studies on champagne wine macromolecules had shown wine macromolecules to be mostly proteins and polysaccharides [8] with very little insight as to the chemical constitution. The present study describes the isolation and characterization of these macromolecules and their link with the adsorption layer