A major showcase for the compound semiconductor community, Compound Semiconductors 2002 presents an overview of recent developments in compound semiconductor physics and its technological applications to devices. The topics discussed reflect the significant progress achieved in understanding and mastering compound semiconductor materials and electronic and optoelectronic devices. The book covers heteroepitaxial growth, quantum confined emitters and detectors, quantum wires and dots, ultrafast transistors, and various compound materials.

Since 2001 the Statistical Offices in Germany offer access to micro level panel data that linked information from various waves of a survey over time. These panel data enormously extended the research potential of data from official statistics by allowing dynamic analyses and control for unobserved heterogeneity via panel econometric methods. A second generation of data sets which became available recently has an even higher research potential. These new data combine information for firms gathered in different surveys (or from external sources) that could not be analyzed jointly before. Merging firm level data from different surveys to construct data sets that cover information on a wider range of variables than the ones collected in any of these surveys, one at a time, is the basic idea of the project AFiD. AFiD is an acronym for the German Amtliche Firmendaten fur Deutschland (official firm data for Germany). The papers in this issue present first results generated with this new type of firm level data and discussions.

In many parts of vertebrate and invertebrate central nervous systems, groups of nerve or receptor cells can be found that are arranged and connected according to a precise, functionally defined pattern (Braitenberg, 1973; Santini, 1975; Strausfeld, 1976; Chan-Palay, 1977). In these cases, groups of cell bodies or synapses appear as basically similar configurations, which, however, are different in detail from each other. Such abstract patterns of connectivity are of a statistical nature and do not allow, in a given example, for the prediction of the localization or connections of a particular cell. "Wiring diagrams", therefore, can be obtained only from a multitude of individual observations. In contrast, in several sensory organs, concrete patterns occur that con sist of a regular, mosaic-like, and geometric arrangement of similar cell types. The constancy of such a mosaic allows predictions about certain units of the pattern on the basis of only a few exemplary observations. Typical examples are found in the visual system: In the compound eye of insects, each ommatidium contains a definite number of visual cells that are grouped around the optical axis in a hexogonal array (Kirsch feld, 1967); in the vertebrate retina, mosaics of geometrically arranged cones are found most frequently in lower vertebrates; they are common among teleosts. A number of studies have dealt with their phylogenetic significance and their functional role as adaptation to specific environments or modes of feeding.

"Nitrogen" Suppt. Vol. B 1 describes the compounds of nitrogen with noble gases and, in the major part, binary compounds composed of one nitrogen atom and hydrogen. Nitrogen hydrogen compounds with two and more nitrogen atoms are covered in "Nitrogen" Suppt. Vol. 82. There is some information on various nitrogen-noble gas species, to a large extent because of the interest in their bonding behavior. Experimental data have been obtained chiefly for some singly charged cations, particularly those formed by argon Like ArN + and ArNi. The existence of others has only been established by mass spectrometry. The binary compounds of nitrogen and hydrogen comprise NH, NH , NH , NH , the corre 2 4 5 sponding ions, and some adducts. NH and NH1 are not treated. The predominant part 3 of the volume covers the description of the molecules NH and NH . 8oth species are present 2 in photolytic processes in the atmosphere. They play an essential role in combustion systems regardless of whether the nitrogen stems from the nitrogen-containing fuel or from the air. Thus, much work has been devoted to the understanding of the nitrogen chemistry in combustion and in the atmosphere. The production and detection methods as weiL as the reactions have been comprehensively described. ln addition detailed information is given on the spectral behavior, the knowledge of which is important for detecting the mole cules and for studying their kinetics.

This volume brings together two comprehensive survey studies of the literature on the microeconometrics of international trade. The chapters apply new empirical methods to the analysis of the links between international trade and various dimensions of firm performance such as productivity, profitability, wages, and survival. The studies also include report results for Germany, one of the leading actors on the world markets for goods and services.

Microeconometric Studies of Firms' Imports and Exports spans twenty-four papers with a focus on four topics: applications of advanced microeconometric methods for cross-section and panel data of internationally active firms; cross-country studies using comparable data for firms; studies of exports by business services firms; and new evidence on German firms' trade in goods from transaction data. Applications focus on Germany, the third-largest exporter and importer of goods in the world. Some of these papers are "classic" empirical studies that helped to shape the field of microeconometrics in international trade and are widely cited. The two final papers are hitherto unpublished and include new material. Applications focus on Germany, the third-largest exporter and importer of goods in the world.

For a couple of years, more and more micro-econometric studies in international trade use data on exports and imports on goods that are based on transaction level data collected by the customs. These data cover detailed information on the goods traded, its value, its weight, and the country of destination (for exports) or origin (for imports). In contrast to data from surveys of firms that were used in empirical studies in the past, these data do not only focus on 'who trades and how much', but also on 'who trades how much of which goods of which value and which weight with firms from which countries'. These transaction data have been used in empirical studies that shed light on various aspects of trade in goods for the first time. This book contains a comprehensive survey of the international literature and selected studies that report results for Germany, the third largest exporter and importer of goods in the world market.