RHESSI and SOHO CDS Observations of Explosive Chromospheric Evaporation

Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory. For the first time, cospatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of nonthermal electrons accelerated during the impulsive phase of an M2.2 flare. When we assumed a thick-target model, the injected electron spectrum was found to have a spectral index of similar to 7.3, a low-energy cutoff of similar to 20 keV, and a resulting flux of >= 4 x10(10) ergs cm(-2) s(-1). The dynamic response of the atmosphere was determined using CDS spectra; we found a mean upflow velocity of 230 +/- 38 km s(-1) in Fe (XIX) (592.23 angstrom) and associated downflows of 36 +/- 16 and 43 +/- 22 km s(-1) at chromospheric and transition region temperatures, respectively, relative to an averaged quiet- Sun spectra. The errors represent a 1 j dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory.

The Diminishing Returns to Trade Policy in the European Union

The notion that the EU is a trade power is central to studies of the Union’s international presence. Credible threats to withhold access to Europe’s markets are said to provide the Union with leverage in respect of other trade partners. This paper queries the continuing ability of the European Union to act effectively this way. The current Doha malaise is a symptom of deeper changes in the international trade system. As emerging markets become more affluent and participate in foreign direct investment, their interest in market access per se become less important relative to other areas of regulation.

International order flows: Explaining equity and exchange rate returns

Macroeconomic models of equity and exchange rate returns perform poorly at high frequencies. The proportion of daily returns that these models explain is essentially zero. Instead of relying on macroeconomic determinants, we model equity price and exchange rate behavior based on a concept from microstructure – order flow. The international order flows are derived from belief changes of different investor groups in a two-country setting. We obtain a structural relationship between equity returns, exchange rate returns and their relationship to home and foreign equity market order flow. To test the model we construct daily aggregate order flow data from 800 million equity trades in the U.S. and France from 1999 to 2003. Almost 60% of the daily returns in the S&P100 index are explained jointly by exchange rate returns and aggregate order flows in both markets. As predicted by the model, daily exchange rate returns and order flow into the French market have significant incremental explanatory power for the daily S&P returns. The model implications are also validated for intraday returns.

Evolutionary agglomeration theory: increasing returns, diminishing returns, and the industry life cycle

According to Marshall’s agglomeration theory, Krugman’s New Economic Geography models, and Porter’s cluster policies, firms should receive increasing returns from a trinity of agglomeration economies: a local pool of skilled labour, local supplier linkages, and local knowledge spillovers. Recent evolutionary theories suggest that whether agglomeration economies generate increasing returns or diminishing returns depends on time, and especially the evolution of the industry life cycle. At the start of the twenty-first century, we re-examine Marshall’s trinity of agglomeration economies in the city-region where he discovered them. The econometric results from our multivariate regression models are the polar opposite of Marshall’s. During the later stages of the industry life cycle, Marshall’s agglomeration economies decrease the economic performance of firms and create widespread diminishing returns for the economic development of the city-region, which has evolved to become one of the poorest city-regions in Europe.

Increasing Returns and Competitive Equilibrium--The Content and Development of Marshall's Theory

This paper reviews Alfred Marshall's attempts to reconcile increasing returns and competition from the early economic writings to the later editions of his Principles. It is shown that while Marshall's final solution to the problem involved naming external economies the cause of increasing returns in a regime of competition , both the life cycle of the firm and internal economies remained necessary to his argument. Their function was to give some operation al content to the elusive concept of external economies.

Commonality in Returns, Order Flows, and Liquidity in the Greek Stock Market

Using a unique high-frequency data-set on a comprehensive sample of Greek blue-chip stocks, spanning from September 2003 through March 2006, this note assesses the extent and role of commonality in returns, order flows (OFs), and liquidity. It also formally models aggregate equity returns in terms of aggregate equity OF, in an effort to clarify OF's importance in explaining returns for the Athens Exchange market. Almost a quarter of the daily returns in the FTSE/ATHEX20 index is explained by aggregate own OF. In a second step, using principal components and canonical correlation analyses, we document substantial common movements in returns, OFs, and liquidity, both on a market-wide basis and on an individual security basis. These results emphasize that asset pricing and liquidity cannot be analyzed in isolation from each other.

Dynamic Density Forecasts for Multivariate Asset Returns

We propose a simple and flexible framework for forecasting the joint density of asset returns. The multinormal distribution is augmented with a polynomial in (time-varying) non-central co-moments of assets. We estimate the coefficients of the polynomial via the Method of Moments for a carefully selected set of co-moments. In an extensive empirical study, we compare the proposed model with a range of other models widely used in the literature. Employing a recently proposed as well as standard techniques to evaluate multivariate forecasts, we conclude that the augmented joint density provides highly accurate forecasts of the “negative tail” of the joint distribution.

Rule Britannia!: British Stock Market Returns, 1825-1870

This article presents a new series of monthly equity returns for the British stock market for the period 1825-1870. In addition to calculating capital appreciation and dividend yields, the article also estimates the effect of survivorship bias on returns. Three notable findings emerge from this study. First, stock market returns in the 1825-1870 period are broadly similar for Britain and the United States, although the British market is less risky. Second, real returns in the 1825-1870 period are higher than in subsequent epochs of British history. Third, unlike the modern era, dividends are the most important component of returns.

'Diminishing Returns' (diary)

Diary