"Ich habe es doch selbst erlebt ..." : die Geschichtswissenschaft und die Tücke des Gedächtnisses – über die Kooperation mit Neurowissenschaften

Das Gedächtnis arbeitet nicht für Historiker. Es dient dem Leben, und dieses bedarf fließender Anpassungen des erworbenen Wissens an die Anforderungen der Gegenwart und Zukunft. Die Erkenntnisse der Hirnforschung fordern die Historiker heraus: Sie sollten nicht nur erforschen, wie es war, sondern wie Erinnerungskulturen funktionieren. Dazu bedürfen sie der Kooperation mit den Kognitionswissenschaften

Donation of Constantine and Constitutum Constantini

The Donation of Constantine is the largest and most powerful forgery in world history. Disputed until modern times, this document was the fuel of religious war, used by both the reformation, as well as the counter-reformation. Johannes Fried not only reinterprets the origin of this forgery (i.e. he ascribes it to the Franks` opposition of Emperor Louis the Pious), but retells, as well, the history of its misinterpretation since the High Middle Ages

Donation of Constantine and Constitutum Constantini

The Donation of Constantine is the largest and most powerful forgery in world history. Disputed until modern times, this document was the fuel of religious war, used by both the reformation, as well as the counter-reformation. Johannes Fried not only reinterprets the origin of this forgery (i.e. he ascribes it to the Franks` opposition of Emperor Louis the Pious), but retells, as well, the history of its misinterpretation since the High Middle Ages

"Wer Weisheit begehrt, der komme zu uns!" : Gelehrte auf Wanderschaft - Aspekte der Mobilität im Mittelalter

Wanderschaft war ein Grundzug des Mittelalters. Könige, Kaufleute, Bettler und Ganoven, die Wanderarbeiter der Bauhütten, die Söldner der großen Armeen, in ihrem Gefolge die Dirnen, dann die Studenten und nicht wenige Professoren: Sie alle hatten lange Jahre der Wanderschaft und der Fremde zu überstehen, bevor sie sich – wenn überhaupt – irgendwo dauerhaft niederlassen konnten. Seit dem 10. und frühen 11. Jahrhundert beklagten die Grundherren die Flucht ihrer Hintersassen, die in die Städte zogen oder sonst wohin, um dort ihr Glück zu machen. Mobilität war ein Wesenselement der ganzen Epoche

Stability of vertical magnetic chains

A linear stability analysis is performed for a pair of coaxial vertical chains made from permanently magnetized balls under the influence of gravity. While one chain rises from the ground, the other hangs from above, with the remaining ends separated by a gap of prescribed length. Various boundary conditions are considered, as are situations in which the magnetic dipole moments in the two chains are parallel or antiparallel. The case of a single chain attached to the ground is also discussed. The stability of the system is examined with respect to three quantities: the number of balls in each chain, the length of the gap between the chains, and a single dimensionless parameter which embodies the competition between magnetic and gravitational forces. Asymptotic scaling laws involving these parameters are provided. The Hessian matrix is computed in exact form, allowing the critical parameter values at which the system loses stability and the respective eigenmodes to be determined up to machine precision. A comparison with simple experiments for a single chain attached to the ground shows good agreement

Single degree of freedom everting ring linkages with nonorientable topology

Linkages are assemblies of rigid bodies connected through joints. They serve as the basis for force- and movement-managing devices ranging from ordinary pliers to high-precision robotic arms. Aside from planar mechanisms, like the well-known four-bar linkage, only a few linkages with a single internal degree of freedom-meaning that they can change shape in only one way and may thus be easily controlled-have been known to date. Here, we present "Mobius kaleidocycles," a previously undiscovered class of single-internal degree of freedom ring linkages containing nontrivial examples of spatially underconstrained mechanisms. A Mobius kaleidocycle is made from seven or more identical links joined by revolute hinges. These links dictate a specific twist angle between neighboring hinges, and the hinge orientations induce a nonorientable topology equivalent to the topology of a [Formula: see text]-twist Mobius band. Apart from having many technological applications, including perhaps the design of organic ring molecules with peculiar electronic properties, Mobius kaleidocycles raise fundamental questions about geometry, topology, and the limitations of mobility for closed loop linkages

Isolation of macro-nuclear DNA from the rumen ciliate Entodinium caudatum

A method is described which allows isolation of macronuclear DNA from the rumen ciliate Entodinium caudatum. Ciliate cells were enriched from the total microbial population in the rumen of sheep with a single ciliate species present by sedimentation and size filtration. Ciliates were then lysed by homogenisation and the macronuclear component isolated on a Percoll density gradient. Macronuclei can be stored in guanidine. HCl until ready for DNA extraction. DNA which had been extracted from macronuclei fresh from the Percoll gradient, or following guanidine. HCl storage, is of sufficient quality to permit its use for PCR analysis

Construction of Unknotted and Knotted Symmetric Developable Bands

We describe a method for constructing developable bands with N ≥ 3 half twists. Each band is formed by threading a flat rectangular strip through a scaffold made from identical circular cylinders and smoothly connecting its short ends. The N cylinders in a scaffold are arranged with N-fold rotational symmetry. The number of half twists in a band is equal to the number N of cylinders in its scaffold and each band inherits the symmetry of its scaffold. Each scaffold admits a family of bands of the same length but variable width up to a maximum value determined by the features of the scaffold. Apart from orientable and nonorientable unknots, our method allows for the construction of bands with the topology of torus knots. We detail the geometric properties of the construction, discuss certain fundamental restrictions that must be met to ensure constructability, and calculate the elastic bending energy of each band. The rotational symmetry underlying the construction is essential for obtaining the presented bands, as the general non-symmetric problem is even more complex and has not yet been investigated. The bands and their corresponding scaffolds can be used as structural elements in practical applications, one of which we describe and analyze. The construction serves as a basis for a general framework for building a large variety of scaffolds and the corresponding unstretchable bands. Together, these assemblies can be used in architectural, interior, and machine design. They also open new avenues for the layout of conveyor belts in factories, airports, and other settings