ALBERT

Beschreibung / Inhaltsverzeichnis: PREFACE The CERN Accelerator School (CAS) was founded in 1983 with the aim to preserve and disseminate the knowledge accumulated at CERN (European Organization for Nuclear Research) and elsewhere on particle accelerators and storage rings. This is being achieved by means of a biennial programme of basic and advanced courses on general accelerator physics supplemented by specialized and topical courses as well as Workshops. The chapters included in this present volume are taken from one of the specialized courses, Applied Geodesy for Particle Accelerators, held at CERN in April 1986. When construction of the first large accelerators started in the 1950's, it was necessary to use geodetic techniques to ensure precise positioning of the machines' components. Since that time the means employed have constantly evolved in line with technological progress in general, while a number of specific developments - many of them achieved at CERN - have enriched the range of available instruments. These techniques and precision instruments are used for most of the world's accelerators but can also be applied in other areas of industrial geodesy: surveying of civil engineering works and structures, aeronautics, nautical engineering, astronomical radio-interferometers, metrology of large dimensions, studies of deformation, etc. The ever increasing dimensions of new accelerators dictates the use of the best geodetic methods in the search for the greatest precision, such as distance measurements to 10 -7, riqorous evaluation of the local geoid and millimetric exploitation of the Navstar satellites. At the same time, the powerful computer methods now available for solving difficult problems are also applicable at the instrument level where data collection can be automatically checked. Above all, measuring methods and calculations and their results can be integrated into data bases where the collection of technical parameters can be efficiently managed. In order to conserve the logical presentation of the different lectures presented at the CAS school, the chapters presented here have been grouped under four main topics. The first and the fourth deal with spatial and theoretical geodesy, while the second and third are concerned with the work of applied geodesy, especially that carried out at CERN. Readers involved in these subjects will find in the following chapters, if not the complete answer to their problems, at least the beginning of solutions to them.

Beschreibung / Inhaltsverzeichnis: INTRODUCTION The evaporite deposits of the Werra district, especially in the Hattorf mining field, are considered a worldwide unique location for the occurence of numerous basalt dikes and magmatic fluid phases fixed in salt rocks. In spite of the great number of studies dealing with the magmatites in the Werra region, previous investigations have rarely attempted more than a predominantly 'qualitative' description of the basaltic rocks and the effects of volcanism on the evaporites (see Chapter 2). The method of interpreting the mineralogical and chemical composition of the evaporites at the basalt contact is based on previous works (KNIPPING 1984; KNIPPING & HERRMANN 1985). This study should contribute to understanding (i) the mechanism of intrusion of the basaltic rnelts and (ii) the metamorphic processes occurring in the evaporites caused by mobile phases during volcanism. Hence, the following methods were applied: The mineralogical and chemical description of the basaltic rocks with recent nomenclature including the possible differences between individual dikes and between surface- and subsurface-exposed basalts. Seven surface and 48 subsurface exposures at the Hattorf mine of Kali & Salz AG were studied. Application of the most recent knowledge on basalt genesis for interpreting observational and experimental results. Studies on the sulfur and carbon isotope distributions of the native sulfur from several subsurface exposures and the enrichments of gases (predominantly CO2) in the evaporites. Calculation of the spatial and temporal temperature distribution in the evaporite rocks following intrusion of the basaltic melts. For purposes of clarity a few of the terms which will be used frequently here will first be defined: basalt - all of the intrusive rocks studied can be assigned mineralogically and chemically to the basalt family in a broader sense. Thus, the terms basaltic rock or, in short, basalt will be used for these rocks. rock salt - instead of the term salt for halitic rocks the term rock salt is used. Besides, the evaporites are generally designated as host rocks (for the basalt dikes) as well. gases - especially in the German literature the term carbon dioxide or carbonic acid (= Kohlensäure) is frequently used for the gases enclosed in the evaporites of the Werra-Fulda district. ACKERMANN et al (1964) found, in addition to carbon dioxide, considerable amounts of nitrogen and minor amounts of methane. In the following therefore the terms gas mixture or gas will be used. The various basalt dikes found in the Hattorf mining field are described here in terms of their mineralogy and geochemistry for the first time. In doing so it is necessary to number them from east to west. To avoid confusion with older numerations (e.g. SIEMENS 1971) the various dike systems are designated by capital letters (A to P).

Beschreibung / Inhaltsverzeichnis: Biolaminated deposits, produced by microbial communities, were studied in modern peritidal environments and in the rock record. The term microbial, mat refers to modern, the term stromatolite to ancient analogs. The term biolaminated deposits was used to encompass both microbial mats and stromatolites. Microbial mat environments studied are the Gavish Sabkha, the Solar Lake, both hypersaline back-barrier systems at the Gulf of Aqaba, Sinai Peninsula, and the "Farbstreifen-Sandwatt" (versicolored sandy tidal flats) on Mellum, an island in the estuary embayment of the southern North Sea coast. Three facies-relevant categories were distinguished: (i) the mat-forming microbiota, (2) environmental conditions controlling mat types and lithology, (3) bioturbation and grazing. Cyanobacteria account for biogenic sediment accretion in all cases studied. Three major groups occur: filamentous cyanobacteria, coccoid unicells with binary fission and those with multiple fission. In the presence of these groups the following mat types evolve: (i) continuously flat (stratiform) L~-laminae (occur in all environments studied); (2) translucent, vertically extended Lv-laminae (only Gavish Sabkha and Solar Lake); (3) nodular granules (only Gavish Sabkha). Basically, the development of mats is controlled by moisture. Thus high-lying parts where the groundwater table runs more than 40 cm below surface are bare of mats. These are: The circular slope and elevated center of the Gavish Sabkha, the shorelines of the Solar Lake and the episodically flooded upper supratidal zone of Mellum Island. The following situations of water supply were found to stimulate mat growth: (i) Capillary movement of groundwater to exposed surfaces, (2) shallowest calm water, both realized in the Gavish Sabkha and the Solar Lake. On Mellum Island, mats form in the lower supratidal zone, which is flooded in the spring tide cycle and wetted during low tide by capillary groundwater. Salinity is almost that of normal seawater, whereas in the Solar Lake, it ranges from 45 °/oo to 180 °/oo and in the Gavish Sabkha, it reaches more than 300 °/oo. Salinity increase is correlated with rising concentrations of magnesium and sulfate ions. In the Gavish Sabkha, episodic sheetfloods cause high-rate sedimentation which is accidental to the living mats. Episodic low-rate sedimentation stimulates the mats to grow through the freshly deposited sediment layer. This occurs predominantly on Mellum Island due to eolian transport. Within the Gavish Sabkha, mineralogy of sediments, community structures, standing crops, redox potentials and pH are highly correlative to the increasing evenness in moisture supply which is realized by the inclination of the system below mean sea level. These conditions bring about a lateral sequence of facies types which include (I) siliciclastic biolaminites at the coastal bar base, (2) nodular to biolaminoid carbonates at saline mud flats, (3) regularly stratified stromatolitic carbonates with ooids and oncoids within the hypersaline lagoon, (4) biolaminated sulfate towardthe elevated center. High-magnesium calcite in facies type 3 precipitates around decaying organic matter and forms also the ooids and oncoids. These occur predominantly within hydroplastic Lv-laminae which provide numerous nucleation centers. Within the Solar Lake, facies type 3 (stromatolitic carbonates with ooids and oncoids) is most important, and grows to extraordinary thickness at the lake's shelf. The regular alternation of dark and light laminae results from seasonally oscillating water depths. These conditions couple back over changing light and salinity intensities to changing dominance structures of mat-building communities. Increasing salinity correlates with decreasing water depth and accounts for the relative abundance of coccoid unicells and diatoms, both active producers of extracellular slimes (Lv-laminae). Water depths locally or temporarily increased favor surface colonization by Mic~ocoleu8 chthonoplastes (Lh-laminae). The biolaminated deposits of the versicolored tidal flats on Mellum Island are similar to facies type 1 of the Gavish Sabkha (siliciclastic biolaminites). Differences exist in the lithology: Sediments upon or through which the mats on Mellum Island grow are made up of clean sand. The grains originate predominantly from re-worked glacial sediments and are rounded to well rounded. By contrast, the strong angularity of siliciclastic grains in the Gavish Sabkha clearly shows their status as primary weathering products. In all environments studied, insects play a significant role. Mainly salt beetles contribute to the lebensspuren spectrum. There is no indication that burrowing and grazing beetles and dipterans are detrimental to the growing mat systems. According to the marine fauna, two distributional barriers exist: (i) physical and (2) biogeochemical factors. Physical barriers are (a) hypersalinity and barrier-closing, which restrict the marine fauna in the Gavish Sabkha and the Solar Lake to a few species, mainly meiofaunal elements such as ostracods and copepods. Only in the Gavish Sabkha, one marine gastropod species occurs which colonizes mud flats of lower salinity. A salinity barrier of about 70 °/oo separates the gastropod habitats from the zones of growing mats. Under reduced salinity, the snails are able to destroy the microbial mats completely. (b) Decreasing regularity of flooding in the microbial mat environment of Mellum Island excludes intertidal deformative burrowers such as cockles and lugworms. However, locally the mats are pierced by numerous dwelling traces. These stem from small polychaetes and amphipod crustaceans which are able to spread over the intertidal-supratidal boundary and settle up to the MHWS-Ievel. Biogeochemical barriers are oxygen depletion within the sediments, high ammonia and sulfide contents, which generate through bacterial break-down of organic matter. Within the highly productive mats of Mic~ocoleu8 chthonoplastes on Mellum Island, dwelling traces of marine polychaetes and amphipod crustaceans disappear due to these conditions. The name of the mat-forming species, Microcoleus chthonoplastes, indicates its capacity to form "soils" (Greek chthonos). While lithology is not altered, the presence of Mic~ocoleu8 mats leads to a habitat change which excludes trace-making "arenophile" invertebrate species and favors "chthonophile" species which do not leave traces. Stromatolitic microstructures studied in rock specimens were interpreted using modern analogs: Microcolumnar buildups in Precambrian stromatolites, ooids and oncoids were compared with those of modern microbial mats. The nodular to biolaminoid facies type found in the Gavish Sabkha was suggested to be an analog to the Plattendolomite facies of Permian Zechstein, North Poland. Studies of the Lower Jurassic ironstone of Lorraine clearly indicate that fungi have been involved in the formation of stromatolites, ooids and oncoids. In conclusion, the comparative study of microstructures in microbial mats and stromatolites reveals a better understanding in both fields. In many cases, it was geology which first revealed the similarity of recent forms to those ancient ones and consequently encouraged research into them.

Beschreibung / Inhaltsverzeichnis: PREFACE The Lower Triassic Buntsandstein in Middle Europe which originated in mainly continental fluvla] environment in the Mid-European Triassic Basin is a famous terrestrial red bed sequence that is discussed in the geological literature since more than 200 years. Much of the earlier work had been devoted to stratigraphical, palaeogeographical and petrographical problemsof the Buntsandstein. The sedimentological analysis and deposltional modelling in the German-type facies, however, is the youngest branch of Buntsandstein investigation and started only a few decades ago. During the last ten years when I began to concentrate on the interpretation of the genesis of the Buntsandstein, much work has been carried out and has already been documented in numerous papers that focussed on various aspects of sedimentology, particularly on reconstruction of fluvial and aeolian depositional mechanisms, significance of palaeosols, importance of fluvial conglomerates, palaeoecology of the fossils, interdisciplinary sedimentology, diagenesis of heavy minerals and origin of the red colour. A summary of the present knowledge in the western part of the German Basin is given in a compilation of regional articles together with general discussions and comparative contributions and especially with an extensive colour photographic documentation in an earlier book (reference on p. 12). In the last few years when more and more material became available not only from the Buntsandstein s. str. (Lower Triassic Scythian) in the Mid-European Triassic Basin, but also from correlative sequences in adjoining areas and even older or younger series of similar facies and origin, it became more and more evident that a synthesis of the state of the art would be necessary, if not inevitably for outlining the general frame and illustrating the diversification of facies associations in numerous temporal and spatial scales. That is why I decided to edit an international proceedings volume on the Buntsandstein which is to compile contributions from many regions and different stratigraphic units with emphasis on various aspects of fluvia] sedi~ntation, but stressing also the importance of the distribution of associated environments such as aeolian dunes and calcrete palaeosols. In spite of my own enthusiasm for the Buntsandstein continental red bed formation (the Lower Triassic red rocks seem to have a very special flavour for being so attractive for me) and regardless of the expansion of my investigations from my original Eife] area (where I learnt how to assess the facies assoCiations in terms of depositional modelling and where I collected an enormous amount of data that served as a valuable base for the production of various case studies which were published during the last years) to several other regions, it was without any doubt that it would not be possible for me alone to finish such an overregional proceedings book within a reasonable time, but that I had to beg various colleagues for their collaboration by writing papers on the Buntsandstein in their investigated areas for this volume. Although the response to my first and second circulars soon showed that it would not be possible to publish a compilation of articles from almost all the studied regions, formations and aspects within a reasonable time with avoiding too much delay of appearance for early contributors, I am very happy that finally many colleagues provided me with papers from almost all the countries in Europe where Buntsandstein is cropping out at the surface. In spite of the tremendous editorial work which was necessary to polish the English, to improve the contents of text and drawings and to put the sequence of papers into a general stream line, I would like to thank all my colleagues who contributed to this volume for their support of the project and particularly for their understanding of my editorial task, especially in case of my frequently serious intervention into their early manuscripts and illustrations. Looking for a publisher in the early stages of planning the volume, I found immediately support by Dr. W. Engel (Department of Geological Sciences of the Springer- Verlag) who generously offered me to take the book into the newly founded series "Lecture Notes in Earth Sciences". From the beginning of organization, writing and editing, I appreciated very much the close cooperation with Dr. Engel who always had an ear for my problems and gave me the necessary freedom to finish the volume along the lines of my intention. Although the preparation of the camera-ready manuscript leaves nearly all the work and responsibility with the author, I am especially grateful to Dr. Engel for his guarantee of almost immediate publication after receipt of the final manuscript which allowed me to polish and incorporate latest ideas up to the very terminal moment. Writing on a subject like the Buntsandstein which has proven to be considerably diversified in terms of sedimentary processes and depositional mechanisms, it became soon apparent that a full discussion along my original intention would easily end up with several thousands of pages in size and would consume much more than a few years. Having already rePeatedly experienced in the past that during course of incorporation of nearly all the relevant literature, the reference l i s t of the final paper is often longer than the whole first draft of the article after one or two years collection of data and ideas, there was no other way than to decide to keep the bibliography short. In order to restrict the book to an economical frame and not to frighten the readership to death, but especially to avoid drowning of the red line through the volume, many contributions had to be written as summary presentations without detailed discussion of the literature. Speaking particularly for the articles that have been written by myself either alone or together with friends, I can assure that this is by no means the result of proud neglectance of other works, but only the necessity of streamlining of the book, and that much of the detailed discussion of comparative examples from the literature has to be done in subsequent special papers. It is impossible to acRnowledge all the people that helped me to arrive at the present goal. Special merits, however, deserve those who stimulated my interest for the Buntsandstein. I am especially indebted to Prof. Dr. G. Fuchs (Landessammlungen fur Naturkunde, Karlsruhe) who proposed me ten years ago to work on the Eifel Buntsandstein for my M.Sc. Thesis, and who later supervised together with Prof. Dr. W. Dachroth (Department of Geology and Palaeontology, University of Heidelberg) the preparation of my Ph.D. Thesis. The good luck of the former to choose the Eifel for me as a starting region (which later proved to have a key position for approaching the evolution of fluvial sedimentation in many other Buntsandstein areas), and the earlier investigations of the latter (although largely unpublished and even only briefly touched in his contribution to this volume) triggered my love of the Buntsandstein which has reached a preliminary climax with the present book. It is my pleasure to dedicate this volume to my two former supervisors with very many thanks for their support and in honour of their merit to have lighted the fire. It is my sincere wish to acknowledge again all the people who contributed with articles to this volume for their help to prepare this summary of the state of the art of Buntsandstein fluvial sedimento]og~y. I also want to sincerely thank all friends and colleagues who supplied ideas and facts in oral or written form and who guided me in the field during course of my comparative investigations that helped me considerably in proceeding with the interpretation of the Buntsandstein. Thanks are also due to Helmut Mader (my father) and Martha Herrmann (my aunt) for their support. I am further indebted to those who have been involved in the various technical aspects of the preparation of the manuscript from the beginning of word processor typesetting of the text and reprography of the illustrations to the final printing. I do hope that the compilation of articles on fluvial aspects of the Buntsandstein in this book will stimulate the interest of many people in the topic of sedimentological modelling of terrestrial red bed sequences and will internationally highlight the position of the Buntsandstein as an extraordinarily attractive case history of fluvial deposition.

Beschreibung / Inhaltsverzeichnis: This volume contains the contributions which have been presented at the 5. ALFRED WEGENER-Conference , held in Göttingen, Federal Republic of Germany, 21 - 24 May 1986. This conference was the first international meeting of the IGCP Project 216 :"global biological events in earth history". The aim of the conference was, to discuss (a) the state-of-the-art in respect to the recognition of bio-events and to the analysis of their causes (b) the presentation of new data (c) the strategies which are needed for further research, carried out in the international cooperation programme of Project 216. It was intended to achieve with these discussions a more critical approach to the problems of global bio-events.

Beschreibung / Inhaltsverzeichnis: PREFACE During the so-called Mid-Cretaceous interval, approximately 100 million years ago, the earth experienced a dynamic phase in its geologic history. Enhanced global tectonic activity resulted in a major rearrangment of the continental plates; accelerated spreading rates induced a first-order sea level highstand; intense off-ridge volcanism contributed to a modeled high atmospheric CO 2 rate; climatic conditions fluctuated; and major changes occurred in biologic evolutionary patterns. With the initiation of a gradual change from an equatorial, east-west directed current-circulation pattern to a regime, dominated by south-north and north-south directed current systems, the earth's internal clock was set for Cenozoic, "modern" times. The Mid-Cretaceous dynamic phase is recorded in a suite of sediments of remarkable similarity around the globe. Shallow-water carbonate platforms drowned on a global scale; widespread sediment-starved, glauconite and phosphate- rich sequences developed; and consequently, pelagic sedimentary regimes "invaded" shelf and epicontinental sea areas. This typical "deepening-upward" pattern is well-documented in Mid-Cretaceous sequences along the northern Tethys margin. Shallow-water carbonates are overlain by condensed glauconitic and phosphatic sediments, which, in turn, are blanketed by pelagic carbonates. In this volume, the example of the western Austrian helvetic Alps, built up of inner and outer shelf sediments deposited along the northern Tethys margin, is used to elucidate the paleoceanographic conditions, under which the Mid-Cretaceous triad of platform carbonates, condensed phosphatic and glauconitic sediments, and pelagic carbonates was formed. In the first part, the evolution of this sequence is traced from the demise of the platform (Aptian) to the return of detritus-dominated deposition (Upper Santonian). The second part includes a discussion of the reconstructed paleoceanographic and tectonic variables, their possible interaction, as well as their influence on sediment properties during this period. Special attention is paid to (1) subsidence behavior of the inner, platform-based shelf and the outer shelf beyond the platform, (2) ammonoid paleobiogeography, (3) the northern tethyan current system and its impact on sediment patterns, (4) the influence of an oxygen minimum zone, (5) sediment bypassing mechanisms on the inner shelf, (6) condensation processes, (7) phosphogenesis, (8) relative sea level changes, (9) genesis and the development of unconformities, (10) tectonic phases and their impact on sediment configuration, (11) drowning of the shallow-water carbonate platform, and (12) "asymmetric" sedimentary cycles. The detailed reconstruction of the development of sedimentary patterns both in time and space in this particular area, and its environmental interpretation, given in this volume, may serve as a contribution to a better understanding of the Mid-Cretaceous dynamic phase in earth's history...

Beschreibung / Inhaltsverzeichnis: INTRODUCTION The awareness that mankind is able to influence and modify not only the local but also the global climate has led to a strongly growing interest in climate research. Strengthened research activities, which also made use of improved and novel experimental techniques, have yielded a wealth of information on climatic patterns in the past. At the same time, climate modelling has made much progress. While some questions have been answered, new problems have been recognized. One question related to anthropogenio climatic change is about the nature and causes of natural variations, against the background of which man-made changes must be viewed. The contributions to this volume all deal with the variabilitY of climate. Some papers are reviews of the knowledge to a current topic, others have more the character of an original contribution. The obseryational studies cover the range from year-to-year variations up to glacial-interglacial contrast, thereby going from instrumental data to results from proxy records...

Beschreibung / Inhaltsverzeichnis: PREFACE This volume comprises the main lectures delivered at the Fourth International Summer School in the Mountains on "Mathematical and Numerical Techniques in Physical Geodesy", held from August 25 to September 5, 1986 in Admont, Austria. The School was organized by the Institute of Theoretical Geodesy of the Technical University Graz, Austria under the auspices of the International Association of Geodesy. All five continents were represented by 70 participants from over 20 countries. The purpose of the Summer School was to provide an introduction to advanced techniques which represent the mathematical vehicle for the treatment of modern geodetic problems, to familiarize participants with the present state of the art of global and local gravity field determination methods, ranging from orbit theory, the key satellite techniques, to inertial and standard terrestrial methods, and to discuss future scientific developments. The arrangement of this volume matches the sequence of lectures given at the School. The theoretical PART A represents the mathematical framework of modern physical geodesy, the application PART B deals with the key satellite and surface techniques, providing the detailed structure of the earth's gravity field. PART A: One of the main goals in physical geodesy, global and local gravity field determination, is pursued by extensively applying functional analytic methods. Recently special attention is being given to the base function and norm choice problem, and to the establishment of a sound link between density distributions inside the earth as the source and observed or estimated gravity field quantities as the effect. The lectures by C.C. Tscherning focus on this topic. Space and time dependent problems of discrete and continuous type are encountered in modern geodesy nowadays and dealt with in the lectures by F. Sans6. Estimation theory either in its stochastic or statistic formulation plays a key role in the processing of processes like the earth's gravity field. The consistent processing of large structured data sets calls for equally structured numerical algorithms. Spectral analysis with its powerful fast Fourier transform has become a common tool for the treatment of such problems. An introduction to spectral methods, supplemented by numerous examples, is provided by B. Hofmann-Wellenhof and H. Moritz. PART B: The theory of orbit dynamics, tailored to the near circular orbits of most geodetic satellites, is fundamental to modern geodetic satellite techniques and discussed in the lectures by O.L. Colombo. Particular emphasis is put on the interplay between orbit perturbations and the earth's disturbing gravity field and its mapping by satellite techniques like satellite altimetry, satellite-tosatellite tracking and satellite gradiometry. Satellite gradiometry, which is discussed in the lectures by R. Rummel in detail, with regard to the geometric structure of the gravitational field, the observability of the gradients, and the mathematical model underlying the gravity field recovery problem, promises to provide particularly detailed information about the gravity field of our planet. The global structure of the earth's gravity field is described in terms of earth gravity field models which are derived from both satellite and surface data. The many delicate, mathematically as well as numerically challenging problems, related to the consistent processing of very large space distributed data sets, and proposed solutions are presented in the lecture by R.H. Rapp. For many years various attempts have been made to explain the shorter wavelength part of the earth's anomalous gravity field by isostatic phenomena. Recently several high resolution topographicisostatic earth models have been computed based on global digital terrain data using different techniques fo~ the estimation of the parameters of the chosen isostatic model. A declared goal is the maximum smoothing of the observed gravity field by removing the contribution of the topography and its isostatic compensation. This topic is discussed in the lectures by H. SUnkel. Inertial methods are steadily gaining importance, power and application. This is not only due to hardware improvements in terms of precision and reliability, but also due to recent advances in the mathematical and numerical modelling of the system's performance. An investigation of the error characteristics of inertial survey systems and their interaction with the anomalous gravity field, studied in the framework of dynamic system analysis, is the topic of the lectures by K.-P. Schwarz and the key issue for further improvements and possible integrations with other positioning systems. Geodetic data have both geometric and physical ingredients of various nature. Standard geodetic processing procedures aim at a separation of geometry from physics. Integrated geodesy, in contrast, has been designed as a very sophisticated melting pot which handles practically all available geodetic data in a consistent and optimal way.lt handles surface and satellite data with either geometrically or gravity field dominated content, and geophysical data in terms of density and seismic informatlon just as well and represents as such the great synthesis of mathematical modelling in connexion with geodetic data processing techniques; these advanced ideas are presented in the lectures by G. Hein. This volume presents highlights of modern geodetic activity and takes the reader to the frontiers of current research. It is not a textbook on a closed and limited subject, but rather a reference book for graduates and scientists working in the vast and beautiful, demanding but rewarding field of earth science in general and physical geodesy in particular. The editor expresses his appreciation to all authors of this volume for their advice and help in formulating and designing the scientific program of the Summer School, for providing typewritten lecture notes, and for their excellent cooperation.