Teilchengrössemessung mit Hilfe synthetischer Hologramme

Ohne Zusammenfassung     

A classical synthesis of the collagen-like peptides with the sequence Z(GlyProPro)nOBut and their characterization with circular dichroism and ultracentrifugation.

Oligopeptides with the sequence Z(GlyProPro)_nOBu^t (n = 3–7) were synthesized along a clasical pathway. Generally long fragments were condensed in order to allow an easy separation of the products from the reactants. It is established by molecular weight determination and measurements of circular dichroism that the peptides form the collagen-like triple helix in methanol and that they assume the random coil conformation in dilute acetic acid. The circular dichroism spectra agree reasonably well with the corresponding spectra for (ProProGly)₁₀ which was obtained by solid phase synthesis in another laboratory.     

Internal radiation and nature of discharges

Summary A short survey is given of the work of measuring and analyzing the radiation in the far u.v. which originates in the gas of an electric discharge. A new method is briefly described including some preliminary results.     

A noncontextualist account of contextualist linguistic data

The paper takes as its starting point the observation that people can be led to retract knowledge claims when presented with previously ignored error possibilities, but offers a noncontextualist explanation of the data. Fallibilist epistemologies are committed to the existence of two kinds of Kp-falsifying contingencies: (i) Non-Ignorable contingencies [NI-contingencies] and (ii) Properly-Ignorable contingencies [PI-contingencies]. For S to know that p, S must be in an epistemic position to rule out all NI-contingencies, but she need not be able to rule out the PI-contingencies. What is required vis-à-vis PI-contingencies is that they all be false. In mentioning PI-contingencies, an interlocutor can lead S mistakenly to think that these contingencies are NI-contingencies, when in fact they are not. Since S cannot rule out these newly mentioned contingencies and since she mistakenly takes them to be NI-contingencies, it is quite natural that she retract her earlier knowledge claim. In short, mentioning NI-contingencies creates a distortion effect. It makes S think that the standards for knowledge are higher than they actually are, which in turn explains why she mistakenly thinks she lacks knowledge. Conclusion: The primary linguistic data offered in support of contextualism can be explained without resorting to contextualism.     

Inversion of atom diffraction intensities for surface structural determination

Atom diffraction from surfaces has proved to be a very useful method for structural studies on surfaces, particularly for incommensurate layers and hydrogen adlayers which are not easily analyzed with LEED. We have developed a rapid method to obtain the surface corrugation function directly from the measured intensities within the hard wall model. This avoids a tedious search in parameter space to determine surface structures and is valid for surfaces whose corrugation amplitudes are below the Rayleigh limit. We will discuss the method and its sensitivity to experimental errors in determining the diffraction intensities as well as its applicability when only a fraction of the allowed diffraction beams are experimentally accessible.     

Bunched laser cooling of a stored weak 7Li+ ion beam in a pure triplet state

A preparation scheme for a 7Li+ ion beam in a storage ring is presented which provides ions in the metastable triplet states with well controlled longitudinal phase space properties. For both state selective preparation and beam cooling, laser- and electron-cooler forces are applied. The spatial- and momentum distributions of the ions are directly detected by a time resolved measurement of the fluorescence light. At low beam intensities, the remaining heating rate of such a beam is completely determined by residual gas scattering. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kombination zweier Schaltverfahren zur Erzeugung kurzer, intensiver Riesenpulse

Ohne Zusammenfassung     

Regular equimodular sets of matrices for generalized matrix functions

Using expansions of generalized matrix functions by means of cyclic products and principal majors, conditions for regularity of equimodular classes of matrices are found.     

The maximum entropy determination of nuclear densities of calcium isotopes from elastic scattering of alpha particles

Radial moments of the real part of the optical potential for elastic scattering of 104 MeV α particles are used as constraints, in determining the nuclear density of maximal entropy. The potential is related to the density by the folding model.