Localized phonons in thallium-indium by superconductive tunneling

Phonon induced structure in superconductive tunneling curves indicates the existence of localized modes due to light In impurity atoms dissolved in Tl. Their frequencies are higher than the cut-off phonon frequency in pure Tl but slightly lower than expected from mass-defect theory.     

Search for superconductivity in vapour quenched alkaline earth metals and lanthanides

Recent papers by Reale [1–3] report superconducting transitions in vapour quenched films of several alkali-, alkaline earth-, and rare earth metals which were not previously known to be superconducting. We report here a vain effort to verify that Mg, Ba, Ce, Pr, Nd or Yb are superconducting above 0.3 K.Supported by the Swedish National Science Research Council     

Real‐Time IR Study of Ultra‐Thin Film Photopolymerization of Liquid Porphyrin Monomer

By using an advanced polarization modulation infrared reflection adsorption spectroscopy (PM‐IRRAS) device it is possible to study the photopolymerization of an ultrathin layer of a porphyrin monomer in real time. The method can be compared with the indirect UV/Vis method previously introduced by our group. With PM‐IRRAS it is possible to analyze polymerization kinetics of photopolymerization at various temperatures to determine the activation energy of the reaction.

     

On Edge Exchangeable Random Graphs

We study a recent model for edge exchangeable random graphs introduced by Crane and Dempsey; in particular we study asymptotic properties of the random simple graph obtained by merging multiple edges. We study a number of examples, and show that the model can produce dense, sparse and extremely sparse random graphs. One example yields a power-law degree distribution. We give some examples where the random graph is dense and converges a.s. in the sense of graph limit theory, but also an example where a.s. every graph limit is the limit of some subsequence. Another example is sparse and yields convergence to a non-integrable generalized graphon defined on \((0,\infty )\).     

A15 type structure of chromium films and particles

We have observed a metastable structure of chromium, being of the A15 type, both in thisn granular films and in fine single crystal particles. The new phase is not superconducting above 0.5K.     

Pair-breaking in thin superconducting films — the effects on Tc and fluctuation conductivity

The thickness dependent pair breaking parameter, inherent in the Maki-Thompson contribution to the excess conductivity due to superconducting fluctuations, is found to be equal to the observed shift of T_c relative to the bulk value. Measurements were performed on thin amorphous Be_0.7Al_0.3 films produced by vapour quenching.     

A proof of Parisi’s conjecture on the random assignment problem

An assignment problem is the optimization problem of finding, in an m by n matrix of nonnegative real numbers, k entries, no two in the same row or column, such that their sum is minimal. Such an optimization problem is called a random assignment problem if the matrix entries are random variables. We give a formula for the expected value of the optimal k-assignment in a matrix where some of the entries are zero, and all other entries are independent exponentially distributed random variables with mean 1. Thereby we prove the formula 1+1/4+1/9+...+1/k ² conjectured by G. Parisi for the case k=m=n, and the generalized conjecture of D. Coppersmith and G. B. Sorkin for arbitrary k, m and n. AcknowledgementWe thank Mireille Bousquet-Mélou and Gilles Schaeffer for introducing the problem to us. We also thank an anonymous referee for suggesting some improvements of the exposition.