Bielefeld University

About: Bielefeld University is a education organization based out in Bielefeld, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Population & Quantum chromodynamics. The organization has 10123 authors who have published 26576 publications receiving 728250 citations. The organization is also known as: University of Bielefeld & UNIVERSITAET BIELEFELD.

The Sociological Roots of Science

Abstract: In the period from 1300 to 1600 three strata of intellectual activity must be distinguished: university-scholars, humanists, and artisans. Both university- scholars and humanists were rationally trained. Their methods, however, were determined by their professional conditions and differed substantially from the methods of science. Both professors and humanistic literati distinguished liberal from mechanical arts and despised manual labor, experimentation, and dissection. Craftsmen were the pioneers of causal thinking in this period. Certain groups of superior manual laborers (artist-engineers, surgeons, the makers of nautical and musical instruments, surveyors, navigators, gunners) experimented, dissected, and used quantitative methods. The measuring instruments of the navigators, surveyors, and gunners were the forerunners of the later physical instruments. The craftsmen, however, lacked methodical intellectual training. Thus the two components of the scientific method were separated by the social barrier: logical training was reserved for upper-class scholars; experimentation, causal interest, and quantitative method were left to more or less plebeian artisans. Science was born when, with the progress of technology, the experimental method eventually overcame the social prejudice against manual labor and was adopted by rationally trained scholars. This was accomplished about 1600 (Gilbert, Galileo, Bacon). At the same time the scholastic method of disputation and the humanistic ideal of individual glory were superseded by the ideals of control of nature and advancement of learning through scientific cooperation. In a somewhat different way, sociologically, modern astronomy developed. The whole process was imbedded in the advance of early capitalistic society, which weakened collective-mindedness, magical thinking, and belief in authority and which furthered worldly, causal, rational, and quantitative thinking.

Electrical Switching of Antiferromagnetic Mn 2 Au and the Role of Thermal Activation

Abstract: Current-induced switching via N\'eel spin-orbit torque in thin films of the antiferromagnet Mn${}_{2}$Au offers the prospect of a magnetic multilevel nonvolatile memory cell. The authors investigate this switching with experiments and modeling, explaining the strong dependence of the switching amplitude on current density and temperature. They also point out the importance of thermal assistance of the electrical current to the switching. The energy barrier to switching in Mn${}_{2}$Au is high enough to preserve a magnetic state for many years at room temperature, making this system suitable for real-world spintronic devices.

The tracing procedure: A Bayesian approach to defining a solution forn-person noncooperative games

Abstract: The paper proposes a Bayesian approach to selecting a particular equilibrium points * of any given finiten-person noncooperative game Γ as solution for Γ. It is assumed that each playeri starts his analysis of the game situation by assigning a subjective prior probability distributionp j to the set of all pure strategies available to each other playerj. (The prior distributionsp j used by all other playersi in assessing the likely strategy choice of any given playerj will be identical, because all these playersi will compute this prior distributionp j from the basic parameters of game Γ in the same way.) Then, the players are assumed to modify their subjective probability distributionsp j over each other's pure strategies systematically in a continuous manner until all of these probability distributions will converge, in an appropriate sense, to a specific equilibrium points * of Γ, which, then, will be accepted as solution. A mathematical procedure, to be called thetracing procedure, is proposed to provide a mathematical representation for this intellectual process of convergent expectations. Two variants of this procedure are described. One, to be called thelinear tracing procedure, is shown to define a unique solution in “almost all” cases but not quite in all cases. The other variant, to be called thelogarithmic tracing procedure, always defines a unique solution in all possible cases. Moreover, in all cases where the linear procedure yields a unique solution at all, both procedures always yield the same solution. For any given game Γ, the solution obtained in this way heavily depends on the prior probability distributionsp 1,...,p n used as a starting point for the tracing procedure. In the last section, the results of the tracing procedure are given for a simple class of two-person variable-sum games, in numerical detail.

Parameterizations for ice nucleation in biological and atmospheric systems

Abstract: Ice nucleation is an important process in numerous environmental systems such as atmospheric aerosol droplets or biological tissues. Here we analyze two widely used approaches for describing homogeneous ice nucleation in aqueous solutions with respect to their applicability to heterogeneous ice nucleation processes: the lambda approach and the water-activity-based approach. We study experimentally the heterogeneous ice nucleation behaviour of mineral dust particles and biological ice nuclei (Snomax; Pseudomonas syringae) in aqueous solutions as a function of solute concentration for various solutes (sulfuric acid, ammonium sulfate, glucose, and poly(ethylene glycol) with two different molar masses of 400 and 6000 g mol(-1)). We show that the ice nucleation temperature and the corresponding lambda values depend on both the type of ice nucleus and the type of solute, while the water-activity-based approach depends only on the type of ice nucleus when the solution water activity is known. Finally, we employ both approaches to the study of ice nucleation in biological systems such as the supercooling point of living larvae and insects. We show that the behaviour of freeze tolerant and freeze avoiding species can be described using the two approaches and we discuss how the analysis can be used to interpret experimental results of the freezing behaviour of living species.