Bücher veröffentlicht von Springer Netherlands

Iron is a major constituent of the earth crust. However, under alkaline conditions commonly found in arid and semi-arid environments iron becomes unavailable to plants. When plants are affected by a shortage of iron their leaves become yellow (chlorotic), and both plant growth and crop yield are reduced. The roots of plants affected by iron deficiency may develop a series of responses directed to improve iron uptake, such as increased proton excretion and iron reduction capabilities or excretion of iron chela tors called siderophores. Iron deficiency affects major crops worldwide, including some of major economic importance such as fruit trees and others. Correction of iron deficiency is usually implemented through costly application of synthetic chelates. Since these correction methods are very expensive, the competitivity of farmers is often reduced and iron deficiency may become a limiting factor for the maintenance, introduction or expansion of some crops. In spite of the many years devoted to the study of iron deficiency, the knowledge of iron deficiency in soils and plants is still fragmentary in many aspects. We have only incomplete information on the processes at the molecular level that make some plant species and cultivars unable to take and utilize iron from the soil, whereas other plants grow satisfactorily under the same conditions.

Animal cell technology is a growing discipline of cell biology which aims not only to understand structures, functions and behaviors of differentiated animal cells, but also to ascertain their abilities to be used for industrial and medical purposes. The goal of animal cell technology includes the clonal expansion of differentiated cells, the optimization of their culture conditions, modulation of their ability to produce proteins of medical and pharmaceutical importantance, and the application of animal cells to gene therapy, artificial organs and the production of functional foods. This volume gives the readers a complete review of the present state-of-the-art and will be useful for those working in either academic environments or in the biotechnology and pharmaceutical sectors, particularly cell biologists, biochemists, molecular biologists, immunologists, biochemical engineers and all other disciplines related to animal cell culture.

Parallel processing is seen today as the means to improve the power of computing facilities by breaking the Von Neumann bottleneck of conventional sequential computer architectures. By defining appropriate parallel computation models definite advantages can be obtained. Parallel processing is the center of the research in Europe in the field of Information Processing Systems so the CEC has funded the ESPRIT Supemode project to develop a low cost, high performance, multiprocessor machine. The result of this project is a modular, reconfigurable architecture based on !NMOS transputers: T.Node. This machine can be considered as a research, industrial and commercial success. The CEC has decided to continue to encourage manufacturers as well as research and end-users of transputers by funding other projects in this field. This book presents course papers of the Eurocourse given at the Joint Research Centre in ISPRA (Italy) from the 4th to 8 of November 1991. First we present an overview of various trends in the design of parallel architectures and specially of the T.Node with it's software development environments, new distributed system aspects and also new hardware extensions based on the !NMOS T9000 processor. In a second part, we review some real case applications in the field of image synthesis, image processing, signal processing, terrain modeling, particle physics simulation and also enhanced parallel and distributed numerical methods on T.Node.

Outstanding progress in near-infrared detection technology and in real-time image processing has led astronomers to start undertaking all-sky surveys in the 1--2 mum range (project DENIS in Europe and 2MASS in the U.S.A.), surveys which will have a considerable impact in various areas of astronomy. This book gathers the contributions of more than 80 specialists involved in fields of interest as different as low mass stars, late stages of stellar evolution, star formation, stellar populations of the Galaxy and the Magellanic Clouds, the local structure of the Universe, and observational cosmology. It describes the impact on these fields of the exhaustive data bases and catalogs of stars and galaxies that these surveys will provide. The considerable interest of these documents for the future of infrared space and ground-based projects and the complementarity with other currently ongoing or planned surveys in other spectral ranges are emphasized.

The advent of the World Wide Web has changed the perspectives of groupware systems. The interest and deployment of Internet and intranet groupware solutions is growing rapidly, not just in academic circles but also in the commercial arena. The first generation of Web-based groupware tools has already started to emerge, and leading groupware vendors are urgently adapting their products for compatibility and integration with Web technologies. The focus of Groupware and the World Wide Web is to explore the potential for Web-based groupware. This book includes an analysis of the key characteristics of the Web, presenting reasons for its success, and describes developments of a diverse range of Web-based groupware systems. An emphasis on the technical obstacles and challenges is implemented by more analytical discussions and perspectives, including that of Information Technology managers looking to deploy groupware solutions within their organizations. Written by experts from different backgrounds - academic and commercial, technical and organizational - this book provides a unique overview of and insight into current issues and future possibilities concerning extension of the World Wide Web for group working.

This volume reports on the findings of experts on tropical zooplankton gathered at a meeting in Kariba, Zimbabwe, in 1991. Some basic questions were asked on community composition and biodiversity in the tropics versus the non-tropics. Old ideas on the nature of zooplankton, which were found to be wider than the `classical' rotifers, cladocerans and copepods, as well as on the number of species in tropical waters, are now beginning to break down accordingly as more and more blank spots in the tropics are explored and as more in-depth studies on the zooplankton of tropical lakes are becoming available. This volume contains a mix of papers discussing the two alternative controls (bottom-up and top-down) of zooplankton community structure and these constitute another step towards a coherent theory of tropical ecosystem theory.

A revolution similar to that brought by CCDs to visible astronomy is still ahead in IR and submillimeter astronomy. There is certainly no wavelength range which has, over the past several years, seen such impressive advances in technology: large-scale detector arrays, new designs for cooling in space, lightweight mirror technologies. Scientific cases for observing the cold universe are outstanding. Observations in the FIR/Submm range will provide answers to such fundamental questions as: What is the spectrum of the primordial fluctuations? How do primeval galaxies look? What are the first stages of star formation? Most of the international space missions that have been triggered by these questions are presented in detail here. Technological issues raised by these missions are reviewed, as are the most recent achievements in cooling and detector technologies.

Animal cell technology is a growing discipline of cell biology which aims not only to understand structures, functions and behaviors of differentiated animal cells but also to uncover their abilities for industrial and medical purposes. The goal of animal cell technology includes clonal expansion of differentiated cells with useful abilities, optimization of their culture conditions on the industrial scale, modulation of their ability in order efficiently to produce medically and pharmaceutically important proteins, and application of animal cells to gene therapy and formation of artificial organs. This Volume gives the readers a complete review of the present state of the art in Japan, a country where this field is well advanced, as well as in Asia, Europe and the United States. The Proceedings will be useful for cell biologists, biochemists, molecular biologists, biochemical engineers and those in other disciplines related to animal cell culture, working in academic environments as well as in the biotechnology and pharmaceutical industries.

There were two reasons that induced me to plan and to organize this book, the first was the lack of a text entirely devoted to the subject of gas sensors, notwithstanding some books devoted to the various kind of chemical sensors have recently been published. The second reason was the need of introducing the basic topics of gas detection mechanisms to a growing number of researchers active in research and development laboratories of industries and uni versities. The field of chemical sensors is indeed in fast and consistent growth, as it is proved by the increased number of participants to the congresses that were recently held on this subject, namely the Third Meeting on Chemical Sensors (September 24 - 26, 1990, Cleveland), Transducers' 91 (June 24 - 27, 1991, S. Francisco) and EUROSENSORS V (September 30 - October 3, 1991, Rome). Therefore, this book is mainly intended as a reference text for researchers with a MS degree in physics, chemistry and electrical engineering; it reports the last progresses in the R. & D. and in the technology of gas sensors. I choose to deal specifically with the topic of gas sensors because these devices show a very large number of applications in the domestic and industrial field and they are characterized by a great effort of research and development.

As in previous symposia, some current research topics were selected for review and eight invited papers were presented. For the first time a paper was presented on the historical aspects of Rotiferology, covering European research between 1680-1950. A special workshop session was devoted to a debate on a controversial topic: Rotifer Phylogeny. The workshop resulted in a very successful discussion and the integration of scattered evidence and hypotheses on the phylogenetic origin of rotifers, the relationships between major rotifer groups, and the mechanisms of evolution.

Micro Electro Mechanical Systems (MEMS) is already about a billion dollars a year industry and is growing rapidly. So far major emphasis has been placed on the fabrication processes for various devices. There are serious issues related to tribology, mechanics, surfacechemistry and materials science in the operationand manufacturingof many MEMS devices and these issues are preventing an even faster commercialization. Very little is understood about tribology and mechanical properties on micro- to nanoscales of the materials used in the construction of MEMS devices. The MEMS community needs to be exposed to the state-of-the-artoftribology and vice versa. Fundamental understanding of friction/stiction, wear and the role of surface contamination and environmental debris in micro devices is required. There are significantadhesion, friction and wear issues in manufacturing and actual use, facing the MEMS industry. Very little is understood about the tribology of bulk silicon and polysilicon films used in the construction ofthese microdevices. These issues are based on surface phenomenaand cannotbe scaled down linearly and these become increasingly important with the small size of the devices. Continuum theory breaks down in the analyses, e. g. in fluid flow of micro-scale devices. Mechanical properties ofpolysilicon and other films are not well characterized. Roughness optimization can help in tribological improvements. Monolayers of lubricants and other materials need to be developed for ultra-low friction and near zero wear. Hard coatings and ion implantation techniques hold promise.