The multi-stripe travelling salesman problem

In the classical Travelling Salesman Problem (TSP), the objective function sums the costs for travelling from one city to the next city along the tour. In the q-stripe TSP with q ≥ 1, the objective function sums the costs for travelling from one city to each of the next q cities along the tour. The resulting q-stripe TSP generalizes the TSP and forms a special case of the quadratic assignment problem. We analyze the computational complexity of the q-stripe TSP for various classes of specially structured distance matrices. We derive NP-hardness results as well as polyomially solvable cases. One of our main results generalizes a well-known theorem of Kalmanson from the classical TSP to the q-stripe TSP

Systematic Genetic Screens Reveal the Dynamic Global Functional Organization of the Bacterial Translation Machinery

Bacterial protein synthesis is an essential, conserved, and environmentally responsive process. Yet, many of its components and dependencies remain unidentified. To address this gap, we used quantitative synthetic genetic arrays to map functional relationships among >48,000 gene pairs in Escherichia coli under four culture conditions differing in temperature and nutrient availability. The resulting data provide global functional insights into the roles and associations of genes, pathways, and processes important for efficient translation, growth, and environmental adaptation. We predict and independently verify the requirement of unannotated genes for normal translation, including a previously unappreciated role of YhbY in 30S biogenesis. Dynamic changes in the patterns of genetic dependencies across the four growth conditions and data projections onto other species reveal overarching functional and evolutionary pressures impacting the translation system and bacterial fitness, underscoring the utility of systematic screens for investigating protein synthesis, adaptation, and evolution

NESTOR: A neutrino particle astrophysics underwater laboratory for the Mediterranean

Abstract An underwater neutrino astrophysics laboratory, to be located in the international waters off the Southwest of Greece, near the town of Pylos is now under construction. In the last two years a group of physicists from Greece and Russia have carried out two demonstration experiments in 4km deep water, counting muons and verifying the adequacy of the deep sea site. Plans are presented for a 100, 000 m 2 high energy neutrino detector composed of a hexagon of hexagonal towers, with 1176 optical detector units. A progress report is given and the physics potential of a siggle tower with 168 phototubes (currently under construction) is described

The recombinant fusion protein CFP10–ESAT6–dIFN has protective effect against tuberculosis in guinea pigs

Development of effective vaccine candidates against tuberculosis (TB) is currently the most important challenge in the prevention of this disease since the BCG vaccine fails to guarantee a lifelong protection, while any other approved vaccine with better efficiency is still absent. The protective effect of the recombinant fusion protein CFP10–ESAT6–dIFN produced in a prokaryotic expression system (Escherichia coli) has been assessed in a guinea pig model of acute TB. The tested antigen comprises the Mycobacterium tuberculosis (Mtb) proteins ESAT6 and CFP10 as well as modified human γ-interferon (dIFN) for boosting the immune response. Double intradermal immunization of guinea pigs with the tested fusion protein (2 × 0.5 µg) induces a protective effect against subsequent Mtb infection. The immunized guinea pigs do not develop the symptoms of acute TB and their body weight gain was five times more as compared with the non-immunized infected guinea pigs. The animal group immunized with this dose of antigen displays the minimum morphological changes in the internal organs and insignificant inflammatory lesions in the liver tissue, which complies with a decrease in the bacterial load in the spleen and average Mtb counts in macrophages

Supermodularity on chains and complexity of maximum constraint satisfaction

In the maximum constraint satisfaction problem (Max CSP), one is given a finite collection of (possibly weighted) constraints on overlapping sets of variables, and the goal is to assign values from a given finite domain to the variables so as to maximise the number (or the total weight) of satisfied constraints. This problem is NP-hard in general so it is natural to study how restricting the allowed types of constraints affects the complexity of the problem. In this paper, we show that any Max CSP problem with a finite set of allowed constraint types, which includes all constants (i.e. constraints of the form x = a), is either solvable in polynomial time or is NP-complete. Moreover, we present a simple description of all polynomial-time solvable cases of our problem. This description uses the well-known combinatorial property of supermodularity. Keywords: maximum constraint satisfaction, complexity, supermodularity, Monge properties, digraph H-colouring 1 Introduction and Related Work The constraint satisfaction problem (CSP) is a general framework in which a variety of combinatorial problems, including propositional satisfiability and graph colourability, can be expressed in a natural way [5, 8]. In this paper, we study the maximum constraint satisfaction problem (MAX CSP) which is a natural optimization version of CSP. Informally speaking, in a CSP, one is given a finite collection o

СИНТЕЗ ТА ВЛАСТИВОСТІ 2-(ТРЕТ-БУТОКСІМЕТИЛ)-ОКСИРАНА І 2-((2,6-ДІ-ТРЕТ-БУТИЛ-4-МЕТИЛФЕНОКСІ)МЕТИЛ)-ОКСИРАНА

Запропоновано методику синтеза модельних сполук 2-(трет-бутоксіметил)окси-рана і 2-((2,6-ді-трет-бутіл-4-метилфеноксі)-метил)оксирана, для визначення эфективносм отверджувічів в процесах відтвердження эпоксидних смол. Досліджено кінетику реакції отриманих сполук та епоксидної смоли ЕД-20 при 50 °С з комплексом трифторида бору с діметиланіліном у середовищі діетиленгликоля