Labour market regulation, industrial relations and technological regimes: a tale of comparative advantage

In this paper we present comparative evidence from OECD countriesconcerning the impact of labour market institutions and regulationson technological specialization. The interplay between the degreeof labour market flexibility, the system of industrial relationsand the knowledge base of different industries determines theviability of different human resource strategies, thereby shapingthe patterns of comparative advantage. Our empirical resultsshow that countries with coordinated industrial-relations systemsand strict employment protection tend to specialize in industrieswith a cumulative knowledge base. We argue that two mechanismsexplain these patterns. The larger the scope for resorting tointernal labour markets, the lower the adjustment costs imposedby labour market regulation. Furthermore, employment protectionand coordinated industrial-relations regimes, by aligning workers'and firms' bjectives, encourage firm-sponsored training as wellas the accumulation of firm-specific competencies, allowingfirms to fully exploit the potential of the internal labourmarket.     

Some nonlinear and linear elastic properties of Ni40Ti50Cu10 near the martensitic transformation

Linear and nonlinear elastic effects occuring in a single crystal of the ternary alloy Ni₄₀Ti₅₀Cu₁₀ were determined with a modified ultrasonic pulse echo-overlap technique at different temperatures. All linear elastic coefficients could be measured above and below the martensitic transformation supplementing the results of [A. Alippi (Ed.), Proceedings of the International Conference on Acoustics, Rome, 2001]. A large jump of the elastic stiffness c₄₄ could be detected. First nonlinear elastic measurements were performed. No substantial increase of anharmonicity could be found. The maximum stress amplitude was held far below the yield stress of the material.     

Die Abscheidung von polychlorierten Dioxinen und Furanen aus Abgasen mit Aktivkoksverfahren

Removal of Polychlorinated Dioxins and Furans from Off-Gases by Activated Charcoal. Discussions on solid waste incineration are dominated by the formation and emission of polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF). The predominant part of these substances remains in the fly ash, and less than 20% is present in the off-gases. Very stringent emission limits have been stipulated during recent years in many countries. The adsorption of PCDD/PCDF on carbonaceous materials has proved to be a very effective technique for their removal. Experimental results relating to gas clean-up, adsorber types, and concepts for the integration in plants are described.     

Über „Gährung” und „gährende Pflänzchen”: Aus den Anfängen der Gärungsforschung im 19. Jahrhundert

The cultural history of alcoholic fermentation goes back to very early periods of human being. But only in the 19th century the nature of the biological production of alcohol was discovered. In that time chemistry and botany had a different, complementary view to alcoholic fermentation. While the positions of chemists are well-known and much discussed in the historiography of science the contribution of botanists to fermentation research is almost entirely forgotten nowadays. The work of the mycologist Oscar Brefeld, who studied yeast fermentation from 1873 to 1876, illustrates the special botanical view to the ontogenetical side of alcoholic fermentation, to morphological and physiological differences between growing and dying, fermenting and fermented yeast cells, and to the energetic and ecological role of fermentation as well as its universality in vegetable kingdom.     

AC Susceptibility and Upper Critical Fields in Rb3C60

The ac susceptibility of a phase-pure Rb₃C₆₀ sample has been investigated in dc magnetic fields up to 14 T. The upper critical fields show a significant positive curvature near T_c indicating a local pairing mechanism.     

Crack-Tip-Bridging Stresses in Ceramic Materials

A simple approach is presented for the determination of crack-tip-bridging stresses in ceramic materials. The technique utilizes the difference in compliance predicted for a crack of known size and that measured. The bridging stresses for an alumina material that displays considerable R -curve behavior are calculated from measured compliance and crack-length observations. The results are almost identical with those recently reported in the literature. Additional measurements on a more complex "duplex" ceramic that exhibits a very substantial R -curve due to a crack-branching chain reaction are also presented.     

Rissbildung und Zugtragverhalten von mit Fasern verstärktem Stahlbeton am Beispiel ultrahochfesten Betons

Wegen des Problems möglicher Inhomogenitäten der Faserverteilung/‐ orientierung ist der Einsatz von Fasern als alleinige Bewehrung im konstruktiven Ingenieurbau auf wenige Anwendungsgebiete beschränkt (z. B. Aufnahme von Zwangbeanspruchungen). Unter Zugbeanspruchung lässt sich zudem mit den in der Praxis für normalfeste Betone gebräuchlichen Fasergehalten nach der Erstrissbildung kaum ein verfestigendes Verhalten erzielen. Kombiniert man jedoch Stabstahlbewehrung und Faserbewehrung zu einem stahlfaserverstärkten Stahlbeton, so addieren sich die Vorteile beider Verbundwerkstoffe gleichermaßen. Besonders bei erhöhten Anforderungen an die Rissbreite (Größenordnung: unter 0, 1 mm) kann durch gemischte Bewehrung aus Stabstahl und Fasern eine wesentliche Verbesserung gegenüber Stahlbeton erzielt werden. Im Teil 1 dieses Beitrags wurden die für das Verständnis der unterschiedlichen Wirkungsweisen der beiden Bewehrungselemente “Stabstahl” und “Fasern” erforderlichen mechanischen Zusammenhänge dargestellt. Im Teil 2 erfolgt eine Überprüfung der abgeleiteten Beziehungen anhand experimenteller Untersuchungen an gemischt bewehrten Zugelementen aus ultrahochfestem Beton (UHPC). Für UHPC erreicht die Thematik besondere Aktualität, da aus Gründen der Duktilität der Einsatz von Fasen bei diesen Betonen die Regel ist. Der Nachweis der Begrenzung der Rissbreite bei kombinierter Bewehrung wird zudem an zwei Rechenbeispielen veranschaulicht. Crack Formation and Tensile Behaviour of Concrete Members Reinforced with Rebars and Fibres exemplified by Ultra‐High‐Performance Concrete. Part 2: Experimental Investigations and Examples of Application Due to the problem of possible inhomogeneities of fibre distribution/orientation the use of fibres as sole reinforcement is limited in engineering practice to few applications (e. g. coverage of stresses due to constraints). In addition, it is hardly possible to obtain strain hardening after first crack formation with fibre contents commonly used for normal strength concretes. However, if steel fibre reinforcement is used in combination with bar reinforcement, the advantages of both components are additive in the composite material. Especially for enhanced requirements concerning the crack width (order of magnitude: 0.1 mm), with combined reinforcement of rebars and fibres an essential improvement compared to reinforced concrete can be achieved. In part 1 of this contribution the mechanical relationships required for the understanding of the different behaviours of the two reinforcing elements “rebars” and “fibres” have been presented. In part 2 the derived relationships are validated on the basis of experimental investigations on tensile members with combined reinforcement made of ultra‐high‐performance concrete (UHPC). For UHPC the topic is of special interest, because fibres are added to these concretes generally to improve ductility. The crack width control with combined reinforcement is furthermore illustrated by means of two examples.     

Decrease in saccadic performance after many visually guided saccadic eye movements in monkeys

PURPOSE: To investigate the influence of repeated saccades and of background illumination on the metrics and dynamics of visually guided targeting saccades. METHODS: Eye movements were measured by magnetic search coil technique in seven trained monkeys (Macaca mulatta) while they performed many visually guided saccades in the dark or in dim background light. RESULTS: After 2000 to 7000 saccades in the dark, peak eye velocity on the average decreased by 20%, saccadic gain decreased slightly by 4.5%, and saccadic latency increased by 15%. All parameters also showed increased variability. In contrast, when testing was done in dim light, there was little to no change in average saccadic metrics and latency. CONCLUSIONS: The changes in saccadic metrics and dynamics in the dark do not reflect a change of the ocular plant but may reflect a change in the cortical or cerebellar influences on the brain stem burst generator linked to the monkeys attentional state. Background light mostly prevents this change.     

Measurement of DNA damage after exposure to 2450 MHz electromagnetic radiation

Recent reports suggest that exposure to 2450 MHz electromagnetic radiation causes DNA single-strand breaks (SSBs) and double-strand breaks (DSBs) in cells of rat brain irradiated in vivo (Lai and Singh, Bioelectromagnetics 16, 207-210, 1995; Int. J. Radiat. Biol. 69, 513-521, 1996). Therefore, we endeavored to determine if exposure of cultured mammalian cells in vitro to 2450 MHz radiation causes DNA damage. The alkaline comet assay (single-cell gel electrophoresis), which is reportedly the most sensitive method to assay DNA damage in individual cells, was used to measure DNA damage after in vitro 2450 MHz irradiation. Exponentially growing U87MG and C3H 10T1/2 cells were exposed to 2450 MHz continuous-wave (CW) radiation in specially designed radial transmission lines (RTLs) that provided relatively uniform microwave exposure. Specific absorption rates (SARs) were calculated to be 0.7 and 1.9 W/kg. Temperatures in the RTLs were measured in real time and were maintained at 37 +/- 0.3 degrees C. Every experiment included sham exposure(s) in an RTL. Cells were irradiated for 2 h, 2 h followed by a 4-h incubation at 37 degrees C in an incubator, 4 h and 24 h. After these treatments samples were subjected to the alkaline comet assay as described by Olive et al. (Exp. Cell Res. 198, 259-267, 1992). Images of comets were digitized and analyzed using a PC-based image analysis system, and the "normalized comet moment" and "comet length" were determined. No significant differences were observed between the test group and the controls after exposure to 2450 MHz CW irradiation. Thus 2450 MHz irradiation does not appear to cause DNA damage in cultured mammalian cells under these exposure conditions as measured by this assay.