Limitations and Extensions of the Lock-and-Key Principle: Differences between Gas State, Solution and Solid State Structures

The lock-and-key concept is discussed with respect to necessary extensions. Formation of supramolecular complexes depends not only, and often not even primarily on an optimal geometric fit between host and guest. Induced fit and allosteric interactions have long been known as important modifications. Different binding mechanisms, the medium used and pH effects can exert a major influence on the affinity. Stereoelectronic effects due to lone pair orientation can lead to variation of binding constants by orders of magnitude. Hydrophobic interactions due to high-energy water inside cavities modify the mechanical lock-and-key picture. That optimal affinities are observed if the cavity is only partially filled by the ligand can be in conflict with the lock-and-key principle. In crystals other forces than those between host and guest often dominate, leading to differences between solid state and solution structures. This is exemplified in particular with calixarene complexes, which by X-ray analysis more often than other hosts show guest molecules outside their cavity. In view of this the particular problems with the identification of weak interactions in crystals is discussed

Session E9: Function Control of Fish Migration Facilities at the Hydro Power Plant Kostheim at River Main

Abstract: Applying various conventional and modern monitoring methods a function control of downstream migration facilities and turbine passage related mortality was conducted at the Kostheim Hydro Plant (4,9 MW; two Kaplan turbines; Δh max. 3,74 m, at MQ 2,36 m) at the river Main (km 3,2). Furthermore, the perceptibility and passability of a nature-like bypass for upstream migration was examined. Results showed a size selectivity of the bypass caused by an unsuitable entrance position 40 m downstream of the outlet of the turbines. The effectiveness of the downstream migration facilities proved to be low, leading to high mortalities at the trashrack and during turbine passage. The vertical bar trashrack with a bar spacing of 20 mm showed little repellent effect and was passed by most fish up to a size of 20-25 cm total length, causing scale loss and haematoma in Atlantic salmon smolts and cyprinid species. Eels smaller than 65 cm were unable to pass the trashrack and the majority was killed by the trashrack cleaning device. Particularly, smaller eels experienced high mortalities at the turbine passage

Noncovalent interactions: A brief account of a long history

The history of noncovalent interactions is outlined, starting with early interpretations of the symmetry of crystals, then with the fast development of coordination chemistry, and of fundamental analyses in the last century. An attempt is made to provide for the practicing scientists who use noncovalent interactions a historical background of the field, paying credit to often forgotten predecessors. A separate section shows that only in the 20th century instrumentation provided a firm basis for the exploration of noncovalent interactions. Selected examples illustrate the early and rather accurate calculations of some noncovalent energies. With the advent of supramolecular chemistry, noncovalent interactions became a mainstream field of science; this allowed further insight into the nature and strength of these seemingly weak forces. Intermolecular interactions in biological systems have also received early attention. As far as possible, exact references are given for the original publications

Can patterns of everyday consumption indicate lifestyles? A secondary analysis of expenditures for fast moving goods and their social contexts

Ausgangspunkt der vorliegenden Studie bildet die Frage, ob sich Einkaufsformen beim täglichen Verbrauch als grundlegende Indikatoren von Lebensstilen erweisen. Datengrundlage bildet eine Sekundäranalyse von Panel-Daten zum Konsum schnelllebiger Waren, die vom weltweiten Marktforschungsunternehmen GfK im Jahr 1995 erhoben worden sind. Es wird zunächst eine Reihe von Hypothesen aufgestellt und die zugrunde gelegten Daten und die Stichprobe erläutert. Im Hauptteil der Studie werden 15 vollständige Cluster des Kaufverhaltens von Waren aus den Bereichen Nahrungsmittel, Getränke und Hygiene-Artikel untersucht und mit ausgewählten sozialen Indikatoren, wie z.B. sozialer Status, Mentalität und Umweltbewusstsein in Beziehung gesetzt. Die Ergebnisse zeigen, dass selbst der Kauf von schnelllebigen Konsumgütern in breitere Lebensstile eingebettet ist und auch im Zeitverlauf relativ konstant bleibt. (ICI

Virtual Institutes: Between Immersion and Communication

In the two expressions "virtual reality" and "virtual community", the term "virtual" has different meanings. A virtual reality is a depiction or, more generally speaking, a sensuous representation of reality that allows - mainly by means of interactivity - to experience various features of reality without actually being in contact with the reality depicted. Therefore, any interactive depiction that is able to imitate reality to such an extent that a high degree of sensory-motor immersion becomes possible is called a virtual reality (Heim 1998, 6f). Since reality is always much more complex than its depiction and full of unpredictable surprises, hardly ever a user has doubts about the difference between the depiction and the thing depicted. Nevertheless, there are good reasons for preferring the imitation to the reality: at least, the imitation is usually not as dangerous as reality sometimes turns out to be. Accordingly, quite different platforms for virtual institutes may be used emphasizing either the immersion aspect or the communication aspect. The decision for a platform depends on the goals pursued with the institute: text-based chat systems allow virtual communities to flourish, single-user VRML scenes convey a highly immersive 3D impression to its users. This is particularly true for virtual institutes realized as a 3D environment, as well as for corresponding virtual communities since 3D environments are adequate for certain tasks only. As an overall framework for the evaluation it is helpful to distinguish three major application areas: research, presentation, and communicative work. The Virtual Institute for Image Science (VIB), which we would like to describe in the following (3) as a case study, is almost exclusively designed for the third task: communicative working. It intends to provide a working space persons can share for joint projects despite being physically separated. Before describing the VIB in more detail we would like to give an overview of virtual institutes between the poles of realistic immersion and of communication in a community (2). The discussion of the case study leads to some more general considerations about the balance virtual institutes must find along that bi-polar dimension (4). In the concluding remarks we focus on the technical tools for virtual communities in 3D presently available

Beurteilung der Konstitution von Milchkühen anhand der Ausprägung ihrer wesentlichen arttypischen Eigenschaften

Over the past 40 years, dairy cow breeding has led to very high yielding cows (more than doubled average annual milk yields in most dairying countries), but also to a deterioration in cow health, fertility and longevity (Pryce et al. (1999)). Consequently, many breeding organizations all over the world are seeking to include functional traits in their breeding programmes (Groen et al. (1997), Christensen et al. (1998)). A great amount of research is done on potential index traits for indirect selection for health traits (Groen et al. (1997)). The whole constitution of the animals is to some extent considered in Scandinavian breeding programmes using the epidemiological data of all herd book animals (Philipsson et al. (2000)) and in breeding for life time dairy performance (Haiger (2000)). Our working hypothesis is that animal constitution has to do with the intensity of their species-specific character and expression. We propose to develop an evaluation model by comparing the vertebrates’ early embryonic states and their embryonic development: All vertebrates exhibit quite similar early embryonic states. Species-specific differentiation appears during later embryonic development. The specialization of the organ systems occurs with different intensities for each species resulting in different “morphologic valencies” (Portmann (1983)). The “morphologic valency” derives from the degree of differentiation of the organs (Portmann (1983)). It is possible to group the organ systems in a metabolic-limb-system, a rhythmic system (blood circulation and respiration) and a nerve-senses-system (after Schad (1971) and Steiner (1917)). Most animal species develop one of those three organ systems to a great extent. Ruminants develop highly specialized limbs and a highly differentiated digestion system: their four stomachs and their intestinal organs are more complex than those of all other mammals. Their life is dominated by these organs: dairy cows spend at least two thirds of a day eating and ruminating. Animal welfare is strongly influenced by the state of health of those specialized organs. Many cow diseases correlate with imbalances in the digestion system (Lotthammer (1992), Spranger (1998)). To assess animal constitution we propose giving special attention to physiology and behaviour with respect to these highly specialized organs and to the corresponding temperament (most animals with a highly specialized digestion and metabolic system tend to have a calm disposition (Marek et al. (1956)). We are thus looking for links between health, ruminating behaviour, metabolic and digestion parameters and temperament of dairy cows. Such observations need to be done under appropriate animal husbandry conditions. 60 dairy cows on a biodynamic farm in Switzerland were observed in terms of ruminating behaviour (ruminating time per day and per ruminating period, frequency of ruminating periods per day, jaw movements per bolus, chewing time per bolus, ruminating speed), body condition score (BCS after Ferguson et al. (1994)), manure consistency and temperament (nervousness / calmness while being brushed by an unknown person). Most methods for these observations had to be developed (Schneider (2002)). The records thus gained were correlated to the health parameters of the same cows (disease incidence, somatic cell score; methods for this were developed by Silvia Ivemeyer). The cows exhibited individual differences in all parameters. Multiparous cows chewed less and slower than primiparous cows. High yielding multiparous cows chewed less than lower yielding multiparous cows. Chewing time per bolus correlated negatively with mastitis incidence. Nervous cows exhibited higher somatic cell scores and a tendency to higher disease incidences than calm cows. Standard deviations in BCS correlated with metabolic diseases, claw diseases and reproduction problems. Evaluations are ongoing

Design and performance evaluation of next generation clutch control valve

Pressure reducing valves perform various control tasks in mobile machines. In many cases contamination sensitive environments require pilot-operated valves, because of its more robust performance. On the other hand, dynamic valve behavior can be critically in certain applications. Overcoming the restrictions resulting from stand-alone test rig attempts, suitable simulation principles are nowadays the state of art in valve design. Unsuitable model approaches and missing consideration of the application may result in wrong design decisions. This paper discusses two important modeling issues, in particular the solenoid and spool leakage behavior, in combination with the connected system under control, a pressure-actuated clutch. It is shown, that even for standard proportional valves a critical view on customers´excitation strategy and site of installation decides on success or failure of an already used design variant

Die jüdische Gemeinde in Hildesheim von 1871 - 1942

Die Arbeit setzt zwei Schwerpunkte: Sie untersucht die innere Entwicklung der jüdischen Gemeinde in Hitdesheim und sie fragt nach ihrem Verhältnis zur städtischen Gesellschaft, nach dem Maß der Integration. Zu dem ersten Themenbereich gehört die Darstellung des rechtlichen Status der Gemeinde sowie der Aufgaben ihrer verschiedenen Institutionen und ihre Einfügung in die Verfassung der hannoverschen Judenschaft. Über die reine 'Institutionengeschichte' hinaus stehen jedoch auch hier sozialgeschichtliche und mentalitätsgeschichtliche Aspekte im Vordergrund. Das Hauptkapitel zu diesem Bereich ist das zum jüdischen Vereinswesen. Gerade dieses zeigt, daß man auch im Falle Hitdesheims von jener Art Subkultur im Sinne D. Sorkins sprechen kann. Weiteren Aufschluß gab hierüber auch die Untersuchung zweier Streitfalle im Zusammenhang mit der Gestaltung des Gemeindefriedhofes. An ihnen wurde deutlich, wie weit die Gemeinde Ende des 19. Jahrhunderts bereit war, sich auf eine Akkulturation einzulassen und wo sie deren Grenze gezogen sehen wollte. Diesen Fragen wurde im übrigen auch bei der Untersuchung des jüdischen Schulwesens in Hitdesheim nachgegangen. Die Analyse der Architektur der Gemeindebauten zeigte, daß sich an ihnen Aussagen über das Selbstverständnis der Gemeinde treffen lassen und daß der Bau auch die Funktion der Selbstdarstellung der jüdischen Gemeinde erfüllt hat Ein weiterer umfangreicher Abschnitt hat die soziale Struktur der Gemeinde zum Gegenstand, das heißt ihrer beruflichen und sozialen Gliederung, ihrer demographischen Entwicklung. Der zweite Schwerpunkt der Arbeit ist die Untersuchung des Verhältnisses der jüdischen Gemeinschaft zur übrigen Gesellschaft. Ein zentrales Kriterium hierfür waren Einfluß und Akzeptanz antisemitischer Einstellungen innerhalb der städtischen Gesellschaft. Ein eigenes Hauptkapitel untersucht die Zeit von 1933-1942/45. Dabei stehen die vielfachen Verfolgungsmaßnahmen sowie ihre Auswirkung auf die jüdische Gemeinde im Vordergrund -bis hin zu den 1942 einsetzenden Deportationen. Ferner wurde auf die Auswirkungen von Berufsverboten, direktem und indirektem Boykott auf verschiedene Berufsgruppen eingegangen- Untersucht wurde zudem die zunehmende Isolation der jüdischen Bevölkerung sowie der Wandel ihres Selbstverständnisses durch die 'Erfahrung' der Verfolgung

Sicherheit und Zuverlässigkeit im Bauwesen: Grundwissen für Ingenieure

Sicherheit ist eines der wesentlichen Stichworte unserer Zeit, nicht zuletzt auch im Bauwesen. Das Buch durchleuchtet diesen Aspekt in großer thematischer Breite. Als entscheidende Voraussetzung für die Schaffung von Sicherheit im Bauwesen werden im ersten Teil Methoden der Gefährungsanalyse und Elemente der Massnahmenplanung behandelt. Weiter findet sich eine Einführung in das elementare Grundwissen der Statistik und Wahrscheinlichkeitslehre sowie in die Aufarbeitung von Daten in eine von der Zuverlässigkeitstheorie geforderten Form. Den zentralen Teil des Buches bildet die Zuverlässigkeitstheorie in der auf kleine Versagenswahrscheinlichkeiten ausgerichteten Form. Die wichtigsten Rechenverfahren werden unter weitgehendem Verzicht auf Herleitung dargestellt. Beispiele, meist aus dem statisch-konstruktiven Bereich des Bauingenieurwesens, machen das Erläuterte verständlich - auch für einen mit der Thematik wenig vertrauten Leser. Die Gefährdungsanalyse mit logischen Bäumen, d.h. mit Ereignis-, Fehler- und Entscheidungsbäumen ist in den wesentlichen Ansätzen ebenfalls behandelt. Die Sicherheit im Bauwesen wird entscheidend durch Fehlhandlungen der beteiligten Menschen beeinträchtigt. Praxisnah und konkret schildert der Autor, wie die im Bauwesen tätigen Fachleute in den verschiedenen Arbeitsphasen Fehler verhüten bzw. durchgeschlüpfte Fehler noch rechtzeitig entdecken können. Am Schluß wird gezeigt, auf welche Kriterien sich der Entscheid stützt, gewisse Risiken im konkreten Fall zu akzeptieren, denn ohne Risiko kann man bekanntlich nicht bauen. Ein umfangreicher Anhang bietet Hilfsmittel für die praktische Arbeit sowie ausführliche Begriffs- und Literaturverzeichnisse