Shadow Profit Maximization and a Generalized Measure of Inefficiency

Determining the profit maximizing input-output bundle of a firm requires data on prices. This paper shows how endogenously determined shadow prices can be used in place of actual prices to obtain the optimal input-output bundle where the firm.s shadow profit is maximized. This approach amounts to an application of the Weak Axiom of Profit Maximization (WAPM) formulated by Varian (1984) based on shadow prices rather than actual prices. At these prices the shadow profit of a firm is zero. Thus, the maximum profit that could have been attained at some other input-output bundle is a measure of the inefficiency of the firm. Because the benchmark input-output bundle is always an observed bundle from the data, it can be determined without having to solve any elaborate programming problem. An empirical application to U.S. airlines data illustrates the proposed methodology.

Shedding light on the shadow economy : a nighttime light approach

Measuring the shadow economy is inherently difficult, but critical for understanding economic development. Using census data on formal and informal sectors in Cambodia, we document that 96.6% of non-farm establishments do not formally register with the government, and their sales accounted for 76.6% of total sales in 2011. We estimate a relationship between nighttime light and sales across regions separately for formal and informal firms for 2011, and estimate their past sales from changes in nighttime light for 1993-2010. Both formal and informal firms increased their estimated sales, and the share of informal sales increased from 68.8% in 1993 to 76.6% in 2011, suggesting that the informal sector increased quantitatively in both absolute and relative terms throughout the economic development of the Cambodian economy.

Shadow Analysis of Soil Surface Roughness Compared to the Chain Set Method and Direct Measurement of Micro-relief.

Erosion potential and the effects of tillage can be evaluated from quantitative descriptions of soil surface roughness. The present study therefore aimed to fill the need for a reliable, low-cost and convenient method to measure that parameter. Based on the interpretation of micro-topographic shadows, this new procedure is primarily designed for use in the field after tillage. The principle underlying shadow analysis is the direct relationship between soil surface roughness and the shadows cast by soil structures under fixed sunlight conditions. The results obtained with this method were compared to the statistical indexes used to interpret field readings recorded by a pin meter. The tests were conducted on 4-m2 sandy loam and sandy clay loam plots divided into 1-m2 subplots tilled with three different tools: chisel, tiller and roller. The highly significant correlation between the statistical indexes and shadow analysis results obtained in the laboratory as well as in the field for all the soil?tool combinations proved that both variability (CV) and dispersion (SD) are accommodated by the new method. This procedure simplifies the interpretation of soil surface roughness and shortens the time involved in field operations by a factor ranging from 12 to 20.

Modulation instability-induced fading in phase-sensitive optical time-domain reflectometry

Phase-sensitive optical time-domain reflectometry (?OTDR) is a simple and effective tool allowing the distributed monitoring of vibrations along single-mode fibers. We show in this Letter that modulation instability (MI) can induce a position-dependent signal fading in long-range ?OTDR over conventional optical fibers. This fading leads to a complete masking of the interference signal recorded at certain positions and therefore to a sensitivity loss at these positions. We illustrate this effect both theoretically and experimentally. While this effect is detrimental in the context of distributed vibration analysis using ?OTDR, we also believe that the technique provides a clear and insightful way to evidence the Fermi?Pasta?Ulam recurrence associated with the MI process.

1000x shadow-free mirror-based Köhler concentrator

A new design for a photovoltaic concentrator, the most recent advance based on the Kohler concept, is presented. The system is mirror-based, and with geometry that guaranties a maximum sunlight collection area (without shadows, like those caused by secondary stages or receivers and heat-sinks in other mirror-based systems). Designed for a concentration of 1000x, this off axis system combines both good acceptance angle and good irradiance uniformity on the solar cell. The advanced performance features (concentration-acceptance products ?CAP- about 0.73 and affordable peak and average irradiances) are achieved through the combination of four reflective folds combined with four refractive surfaces, all of them free-form, performing Köhler integration 2 . In Köhler devices, the irradiance uniformity is not achieved through additional optical stages (TIR prisms), thus no complex/expensive elements to manufacture are required. The rim angle and geometry are such that the secondary stage and receivers are hidden below the primary mirrors, so maximum collection is assured. The entire system was designed to allow loose assembly/alignment tolerances (through high acceptance angle) and to be manufactured using already well-developed methods for mass production, with high potential for low cost. The optical surfaces for Köhler integration, although with a quite different optical behavior, have approximately the same dimensions and can be manufactured with the same techniques as the more traditional secondary optical elements used for concentration (typically plastic injection molding or glass molding).

Anna Popovitch,In the Shadow of Althusser: Culture and Politics in Late Twentieth-Century Argentina, Ann Arbor, umi Dissertation Publishing, 2011, 238 páginas

Fil: Starcenbaum, Marcelo. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.

In Putin’s Shadow: Dmitry Medvedev’s presidency. OSW Point of View, November 2011

Dmitry Medvedev’s presidency was an experiment carried out by the Russian ruling elite. Even though the new president has been a loyal member of the ruling camp, this decision involved certain risk that the extensive constitutional powers could eventually encourage the new president to seek emancipation, which could provoke internal conflicts and splits in the elite. This paper analyses Medvedev’s presidency and tries to answer the question why this scenario did not take place and why Medvedev failed to overcome the restrictions imposed on him at the start of his presidential term. The paper also presents the activation of certain social groups during Medvedev’s presidency and their calls for a new social contract with the government.

The Middle East in the shadow of the Islamic State. OSW Point of View Number 52, August 2015

Since June 2014, Islamic State (IS) has been regarded as the principal security threat in the Middle East and one of the most important problems for European and global security. Islamic State, which for many years was just one of many terror organisations with links to al-Qaeda, has succeeded in achieving much more than other similar organisations: it has taken over control of large swathes of territory in Syria and Iraq by military means, created its own para-state structures in that area, and become the greatest civilisational challenge for the region in a century as it established a self-proclaimed caliphate and credibly pledged to expand further on a global scale. Those successes have been accompanied by widely publicised acts of systemic brutality which meets the definition of crimes against humanity. One outcome of these developments is the emergence of an exotic informal alliance to combatthe Islamic State, which has brought together all the states from the Middle East and many from beyond the region. However, contrary to what could have been predicted, after almost a year of the declared war against IS, the Caliphate still holds most of the ground it gained in 2014.