On theorems of Jackson and Bernstein type in the complex plane

We consider best polynomial approximation to functions analytic in a Jordan domainD and continuous on \(\bar D\) . We relate theorems of Jackson and Bernstein type to the Hölder continuity of the exterior conformal mapping functions forD.     

Separation of alanine aminotransferase and albumin on various substituted agaroses

A systematic study was made to find an affinity chromatographic purification method for alanine aminotransferase (AAT). Sepharose 4B was derivatized with various substrate-like ligands and the separation of AAT and albumin was tested on gels. The largest separation of the proteins was achieved on an amino ethyl-agarose to which aminooxy alanine was coupled via the peptide bond. The center points of albumin and AAT peaks were 42 and 112 ml, respectively. Aminooxy alanine was the strongest inhibitor of AAT of the ligands tested. Some weak inhibitors, however, were able to separate the proteins, too. It is suggested, based on the results, that the purification mechanism is a combination of hydrophobic, electrostatic, and biospecific affinities.     

Topographical global optimization using pre-sampled points

A method for global minimization of a functionf(x), x A R ⁿ by using presampled global points inA is presented. The global points are obtained by uniform sampling, discarding points too near an already accepted point to obtain a very uniform covering. The accepted points and their nearest-neighbours matrix are stored on a file. When optimzing a given function these pre-sampled points and the matrix are read from file. Then the function value of each point is computed and itsk nearest neighbours that have larger function values are marked. The points for which all its neighbours are marked are extracted as promising starting points for local minimizations. Results from a parallel implementation are presented. The working of a sequential version in Fortran is illustrated.     

Quadrilaterals and extremal quasiconformal extensions

We show that the smallest maximal dilatation for a quasiconformal extension of a quasisymmetric function of the unit circle may be larger than indicated by the change in the module of the quadrilaterals with vertices on the circle. The research of the second author has been partially supported by the Alfred P. Sloan Foundation and by the U.S. National Science Foundation grant DMS 94-00999. This research was completed while the first author was visiting the University of Illinois at Urbana-Champaign. He wishes to thank the Department of Mathematics for its kind hospitality.     

Fluence Rate or Cumulative Dose? Vulnerability of Larval Northern Pike (Esox lucius) to Ultraviolet Radiation

Newly hatched larvae of northern pike were exposed in the laboratory to four fluence rates of ultraviolet radiation (UVR; 290-400 nm) over three different time periods, resulting in total doses ranging from 3.0 +/- 0.2 to 63.0 +/- 4.4 kJ.m(-2). Mortality and behavior of the larvae were followed for 8-12 days, and growth measured at the end of the experiment. Also, the principle of reciprocity-that the UVR-induced mortality depends on the cumulative dose, independent of fluence rate-was tested. Fluence rates higher than 1480 +/- 150 mW.m(-2) caused mortality and growth retardation. The highest fluence rate (3040 +/- 210 mW.m(-2)) caused 100% mortality in 5 days. All fluence rates caused behavioral disorders, which led to death at fluence rates higher than 1480 mW.m(-2). Reciprocity failure occurred with the lowest and highest dose (550 +/- 45 and 3040 +/- 210 mW.m(-2), respectively). The results show that fluence rate is of primary importance when assessing the UVR-related risk.     

Two-photon photoemission study of the coverage-dependent electronic structure of chemisorbed alkali atoms on a Ag(111) surface

We report a systematic investigation of the electronic structure of chemisorbed alkali atoms (Li-Cs) on a Ag(111) surface by two-photon photoemission spectroscopy. Angle-resolved two-photon photoemission spectra are obtained for 0-0.1 monolayer coverage of alkali atoms. The interfacial electronic structure as a function of periodic properties and the coverage of alkali atoms is observed and interpreted assuming ionic adsorbate/substrate interaction. The energy of the alkali atom σ-resonance at the limit of zero coverage is primarily determined by the image charge interaction, whereas at finite alkali atom coverages, it follows the formation of a dipolar surface field. The coverage- and angle-dependent two-photon photoemission spectra provide information on the photoinduced charge-transfer excitation of adsorbates on metal surfaces. This work complements the previous work on alkali/Cu(111) chemisorption [Phys. Rev. B 2008, 78, 085419].     

On the Minimum Distances of Non-Binary Cyclic Codes

We deal with the minimum distances of q-ary cyclic codes of length q ^m - 1 generated by products of two distinct minimal polynomials, give a necessary and sufficient condition for the case that the minimum distance is two, show that the minimum distance is at most three if q > 3, and consider also the case q = 3.