Improved tau polarisation measurement

Using 22 pb⁻¹ of data collected at LEP in 1992 on the peak of the Z resonance, the ALEPH collaboration has measured the polarisation of the tau leptons decaying into ,πν, ρν and a₁ ν from their individual decay product distributions. The measurement of the tau polarisation as a function of the production polar angle yields the two parametersN _τ andN _e, where, in terms of the axial and vector couplingsg _Al andg _Vl,N _l=2g _Vl g_Al/(g _Vl ² +g _Al ² ). This analysis follows to a large extent the methods devised for the 1990 and 1991 data but with improvements which bring a better understanding of the systematic uncertainties. Combining the 1992 measurements with our previously published results yieldsN _τ=0.136±0.012±0.009 andN _e=0.129±0.016±0.005. Assuminge−τ universality, the measurements imply an effective weak mixing angle of sin ² θ _W ^eff =0.2332±0.0014. Deceased     

Design and synthesis of ansamycin antibiotics

Ansamycin antibiotics are a class of microbial metabolites that exhibit an array of biological activities. This review covers the synthetic chemistry and biological activity of benzenic ansamycins from 1989 to 2007. In the first section, synthetic approaches to the C15-benzene ansamycins (geldanamycin and related) are discussed. Access to the C17-benzene ansamycins (or ansatrienins) is disclosed in the second half of this article.     

Synthesis and cytotoxic evaluation of cis-locked and constrained analogues of combretastatin and combretastatin A4

A series of cis-locked stilbenic compounds related to combretastatin and combretastatin A4 has been designed and synthesized. The cytotoxic effects of these rigid analogues were evaluated as well as their abilities to inhibit tubulin polymerization.     

On the probabilistic min spanning tree Problem

We study a probabilistic optimization model for min spanning tree, where any vertex v _i of the input-graph G(V, E) has some presence probability p _i in the final instance G′ ⊂ G that will effectively be optimized. Suppose that when this “real” instance G′ becomes known, a spanning tree T, called anticipatory or a priori spanning tree, has already been computed in G and one can run a quick algorithm (quicker than one that recomputes from scratch), called modification strategy, that modifies the anticipatory tree T in order to fit G′. The goal is to compute an anticipatory spanning tree of G such that, its modification for any G￠ í GG' \subseteq G is optimal for G′. This is what we call probabilistic min spanning tree problem. In this paper we study complexity and approximation of probabilistic min spanning tree in complete graphs under two distinct modification strategies leading to different complexity results for the problem. For the first of the strategies developed, we also study two natural subproblems of probabilistic min spanning tree, namely, the probabilistic metric min spanning tree and the probabilistic min spanning tree 1,2 that deal with metric complete graphs and complete graphs with edge-weights either 1, or 2, respectively.     

Differential approximation of min sat, max sat and related problems

We present differential approximation results (both positive and negative) for optimal satisfiability, optimal constraint satisfaction, and some of the most popular restrictive versions of them. As an important corollary, we exhibit an interesting structural difference between the landscapes of approximability classes in standard and differential paradigms.     

Characterization of gaseous phase and nanoparticles produced in ultra-short pulsed laser ablation of transition metal borides

The plasma produced by ultra-short laser ablation of ZrB₂ and ReB₂ has been studied by ICCD imaging and time and space resolved optical emission spectroscopy. The aim was to clarify the mechanism of deposition leading to the morphology and composition found in the deposited films. The results indicate that for all systems the film characteristics are compatible with a deposition mechanism involving a growth from nanoparticles, ejected directly from the target, whose composition can be interpreted in terms of equilibrium vaporization during the flight from the target to the substrate.     

Availability of Hats That Meet Australian Sun-safety Standards at a Major Canberra Shopping Complex

Good sun-safety practice includes wearing sun-protective hats that must meet defined photoprotective criteria such as the 2017 Australian/New Zealand standard (AS/NZS 4399:2017). This study investigated the availability of sun-safe hats during a three-day cross-sectional survey in November 2019 by visiting every shop in a single large multi-store shopping complex in Australia. Hats were categorized according to whether the target customer was an adult or child prior to the assessment of design suitability for sun safety according to the standard. Of the 260 shops in the study shopping center, 30 (12%) sold hats. Of the 524 hats examined in the study, 69% of all commercially available hats for adults and children did not meet the standard. Of the 9% of hats that had swing tags claiming an Ultraviolet Protection Factor of 50 (UPF-50), about half were not sun safe. Further research is needed to investigate the possibility of whether sun-safety hat standards should be given to retailers of hats for display, or whether manufacturers could be required to put warning labels on all hats that do not meet sun-safety hat standards.     

Some Remarks on Exp-Function Method and Its Applications

Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we present some shortcomings of this method by analyzing the results of recently published papers. We also discuss the possible improvement of the effectiveness of the method.     

Reoptimization of minimum and maximum traveling salesman's tours

In this paper, reoptimization versions of the traveling salesman problem (TSP) are addressed. Assume that an optimum solution of an instance is given and the goal is to determine if one can maintain a good solution when the instance is subject to minor modifications. We study the case where nodes are inserted in, or deleted from, the graph. When inserting a node, we show that the reoptimization problem for MinTSP is approximable within ratio 4/3 if the distance matrix is metric. We show that, dealing with metric MaxTSP, a simple heuristic is asymptotically optimum when a constant number of nodes are inserted. In the general case, we propose a 4/5-approximation algorithm for the reoptimization version of MaxTSP.