Refine
Year of publication
Document Type
- Part of a Book (61)
- Article (59)
- Working Paper (16)
- Conference Proceeding (12)
- Preprint (12)
- Lecture (10)
- Book (3)
- Report (3)
- Other (2)
Language
- English (178) (remove)
Keywords
- Ökosystem (15)
- Antike (12)
- Klimaänderung (12)
- Region Berlin-Brandenburg (10)
- Wasserhaushalt (10)
- Biowissenschaften (8)
- Korpus <Linguistik> (8)
- Kunstgeschichte (8)
- Denkmalpflege (7)
- Historische Gärten (7)
Has Fulltext
- yes (178)
Institute
- Berlin-Brandenburgische Akademie der Wissenschaften (45)
- Veröffentlichungen von Akademiemitgliedern (25)
- Akademienvorhaben Census of Antique Works of Art and Architecture Known in the Renaissance (14)
- Interdisziplinäre Arbeitsgruppe Globaler Wandel (13)
- Interdisziplinäre Arbeitsgruppe Gegenworte - Hefte für den Disput über Wissen (8)
- Akademienvorhaben Alexander-von-Humboldt-Forschung (7)
- Drittmittelprojekt Ökosystemleistungen (7)
- Interdisziplinäre Arbeitsgruppe Historische Gärten im Klimawandel (7)
- Akademienvorhaben Deutsches Wörterbuch von Jacob Grimm und Wilhelm Grimm (6)
- Akademienvorhaben Strukturen und Transformationen des Wortschatzes der ägyptischen Sprache. Text- und Wissenskultur im alten Ägypten (6)
- Akademienvorhaben Altägyptisches Wörterbuch (5)
- Interdisziplinäre Arbeitsgruppe Internationale Gerechtigkeit und institutionelle Verantwortung (4)
- TELOTA - IT/Digital Humanities (4)
- Veröffentlichungen externer Institutionen (4)
- ALLEA (3)
- BBAW (3)
- Interdisziplinäre Arbeitsgruppe Strukturbildung und Innovation (3)
- Interdisziplinäre Arbeitsgruppe Zukunft des wissenschaftlichen Kommunikationssystems (3)
- Akademienunion (2)
- Akademienvorhaben Die alexandrinische und antiochenische Bibelexegese in der Spätantike (2)
- Akademienvorhaben Schleiermacher in Berlin 1808-1834, Briefwechsel, Tageskalender, Vorlesungen (2)
- Drittmittelprojekt Proyecto Humboldt Digital (2)
- Initiative Qualitätsbeurteilung in der Wissenschaft (2)
- Interdisziplinäre Arbeitsgruppe EUTENA - Zur Zukunft technischer und naturwissenschaftlicher Bildung in Europa (2)
- Interdisziplinäre Arbeitsgruppe Gentechnologiebericht (2)
- Akademienvorhaben Corpus Coranicum (1)
- Akademienvorhaben Digitales Wörterbuch der Deutschen Sprache (1)
- Drittmittelprojekt CLARIN-D (1)
- Drittmittelprojekt OCR-D (1)
- Interdisziplinäre Arbeitsgruppe Die Herausforderung durch das Fremde (1)
- Interdisziplinäre Arbeitsgruppe Klinische Forschung in vulnerablen Populationen (1)
- Interdisziplinäre Arbeitsgruppe LandInnovation (1)
- Interdisziplinäre Arbeitsgruppe Psychologisches Denken und psychologische Praxis (1)
- Interdisziplinäre Arbeitsgruppe Sprache des Rechts, Vermitteln, Verstehen, Verwechseln (1)
- Interdisziplinäre Arbeitsgruppe Zukunft der Arbeit (1)
- Veröffentlichungen von Akademiemitarbeitern (1)
Physical principles underlying biological pattern formation are discussed. In particular, the combination of local self-enhancement and long-range (“lateral”) inhibition (Gierer and Meinhardt, 1972) accounts for de-novo pattern formation, and for striking features of developmental regulation such as induction, spacing and proportion regulation of centers of activation in tissues and cells. Part I explains physical principles of spatial organisation in biological development. Part II demonstrates in mathematical terms that and how short-range activation and long-range inhibition are conditions for the generation of spatial concentration patterns. The conditions can be expressed in terms of ranges, rates and orders of reactions. These conditions, in turn, can also be derived by analysis of dynamic instabilities by means of Fourier waves, showing the neither obvious nor trivial relation between the latter approach and the theory based primarily on autocatalysis and lateral inhibition.
Ancient Greek philosophers were the first to postulate the possibility of explaining nature in theoretical terms and to initiate attempts at this. With the rise of monotheistic religions of revelation claiming supremacy over human reason and envisaging a new world to come, studies of the natural order of the transient world were widely considered undesirable. Later, in the Middle Ages, the desire for human understanding of nature in terms of reason was revived. This article is concerned with the fundamental reversal of attitudes, from “undesirable” to “desirable”, that eventually led into the foundations of modern science. One of the earliest, most ingenious and most interesting personalities involved was Eriugena, a theologian at the Court of Charles the Bald in the 9th century. Though understanding what we call nature is only one of the several aspects of his theological work, his line of thought implies a turn into a pro-scientific direction: the natural order is to be understood in abstract terms of ‘primordial causes’; understanding nature is considered to be the will of God; man encompasses the whole of creation in a physical as well as a mental sense. Basically similar ideas on the reconciliation of scientific rationality and monotheistic religions of revelation were conceived, independently and nearly simultaneously, by the Arab philosopher al-Kindi in Bagdad. Eriugena was more outspoken in his claim that reason is superior to authority. This claim is implicit in the thought of Nicholas of Cusa with his emphasis on human mental creativity as the image of God’s creativity; and it is the keynote of Galileo’s ‘Letter to the Grand Duchess Christina’ some 800 years later, the manifesto expressing basic attitudes of modern science. This article in English is based on the monography (in German): A. Gierer “Eriugena, al-Kindi, Nikolaus von Kues - Protagonisten einer wissenschaftsfreundlichen Wende im philosophischen und theologischen Denken”, Acta Historica Leopoldina 29 (1999), Barth Verlag in MVH Verlage Heidelberg, ISBN: 3-335-00652-6
Aggregates of previously isolated cells of Hydra are capable, under suitable solvant conditions, of regeneration forming complete animals. In a first stage, ecto- and endodermal cells sort out, producing the bilayered hollow structure characteristic of Hydra tissue; thereafter, heads are formed (even if the original cell preparation contained no head cells), eventually leading to the separation of normal animals with head, body column and foot. Hydra appears to be the highest type of organism that allows for regeneration of the entire structure from random cell aggregates. The system is particularly useful for studying cell interactions, tissue polarity, pattern formation, and cell differentiation.
The generation of viral mutants in vitro was demonstrated by treatment of the isolated RNA of Tobacco Mosaic Virus by nitrous acid. This agent causes deaminations converting cytosine into uracil, and adenine into hypoxanthine. Our assay for mutagenesis was the production of local lesions on a tobacco variety on which the untreated strain produces systemic infections only. A variety of different mutants are generated in this way. Quantitative analysis of the kinetics of mutagenesis leads to the conclusion that alteration of a single out of the 6000 nucleotides of the viral RNA is sufficient for causing a mutation.
Within the sedimentation diagram of infective RNA preparations isolated from Tobacco Mosaic Virus, undegraded molecules form a sharp peak with a molecular weight corresponding to the total RNA content of the virus particle. Degradation kinetics by ribonuclease is of the linear, single-target type, indicating that the RNA is single-stranded. The intact RNA of a virus particle thus forms one big single-stranded molecule. Quantitative evaluation of the effect degradation by RNA-ase on the infectivity of the RNA shows that the integrity of the entire molecule is required for its biological activity.