Renorming spaces with greedy bases

We study the problem of improving the greedy constant or the democracy constant of a basis of a Banach space by renorming. We prove that every Banach space with a greedy basis can be renormed, for a given \vare>0, so that the basis becomes (1+\vare)-democratic, and hence (2+\vare)-greedy, with respect to the new norm. If in addition the basis is bidemocratic, then there is a renorming so that in the new norm the basis is (1+\vare)-greedy. We also prove that in the latter result the additional assumption of the basis being bidemocratic can be removed for a large class of bases. Applications include the Haar systems in $L_p[0,1]$, $1<p<\infty$, and in dyadic Hardy space $H_1$, as well as the unit vector basis of Tsirelson space

Nitrogenase activity associated with codium species from New Zealand marine habitats

Nitrogenase activity, measured as acetylene reduction, was recorded at rates up to 1028 nmol.h \g * dry weight for Codium adhaerens (Cabr.) Ag. var. convolutum Dellow and Codium fragile (Sur.) Hariot subsp. tomentosoides (Van Goor) Silva collected from New Zealand habitats. In both species the ability to reduce acetylene is invariably associated with the presence of a heterocystous blue-green alga, Calothrix sp., epiphytic or embedded in the Codium thallus. A highly significant (P < 0.001) correlation between heterocyst frequency and nitrogenase activity was found. Nitrogenase and net photosynthesis of the Codium-Calothrix system have different steady-state responses to light intensity, and the kinetics of the two processes also differ in that nitrogenase is slow to respond to illumination or darkening. Glucose additions to Codium did not significantly increase nitrogenase activity. Nitrogenase is relatively insensitive to oxygen tension over the range 0-1.0 atm (0-1.033 kgf.cnT2) and still occurs at 1.5 atm (1.55 kgf.cm"2); this condition is unique in all nitrogenase systems thus far reported. Collectively these facts suggest that Calothrix is the agent primarily responsible for nitrogenase activity in these Codium species

Convexity in partial cubes: the hull number

We prove that the combinatorial optimization problem of determining the hull number of a partial cube is NP-complete. This makes partial cubes the minimal graph class for which NP-completeness of this problem is known and improves some earlier results in the literature. On the other hand we provide a polynomial-time algorithm to determine the hull number of planar partial cube quadrangulations. Instances of the hull number problem for partial cubes described include poset dimension and hitting sets for interiors of curves in the plane. To obtain the above results, we investigate convexity in partial cubes and characterize these graphs in terms of their lattice of convex subgraphs, improving a theorem of Handa. Furthermore we provide a topological representation theorem for planar partial cubes, generalizing a result of Fukuda and Handa about rank three oriented matroids.Comment: 19 pages, 4 figure

The perseverance of Pacioli's goods inventory accounting system

This paper details sources of the 'undoubtedly strange' (Yamey, 1994a, p.119) system of goods inventory records described in Pacioli’s 1494 bookkeeping treatise and traces the longevity and widespread use of this early perpetual inventory recording (EPIR) system in English language texts. By doing so and contrasting this system with the bookkeeping treatment of modern texts, it is shown that the EPIR system persisted as the dominant form of goods inventory accounting for between 400 and 500 years and that the reasons for its demise are worthy of further consideration and research

Advanced brain dopamine transporter imaging in mice using small-animal SPECT/CT

Abstract. The stable marriage problem has recently been studied in its general setting, where both ties and incomplete lists are allowed. It is NP-hard to find a stable matching of maximum size, while any stable matching is a maximal matching and thus trivially a factor two approximation. In this paper, we give the first nontrivial result for approximation of factor less than two. Our algorithm achieves an approximation ratio of 2/(1+L −2) for instances in which only men have ties of length at most L. When both men and women are allowed to have ties, we show a ratio of 13/7(&lt; 1.858) for the case when ties are of length two. We also improve the lower bound on the approximation ratio to 2

Viral population estimation using pyrosequencing

The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an EM algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies.Comment: 23 pages, 13 figure

Set optimization - a rather short introduction

Recent developments in set optimization are surveyed and extended including various set relations as well as fundamental constructions of a convex analysis for set- and vector-valued functions, and duality for set optimization problems. Extensive sections with bibliographical comments summarize the state of the art. Applications to vector optimization and financial risk measures are discussed along with algorithmic approaches to set optimization problems

Modelling and validating three dimensional human normal cervix and cervical cancer tissues in vitro

Objective: The use of three dimensional in vitro systems in cancer research is a promising path for developing effective anticancer therapies. The aim of this study was to engineer a functional 3-D in vitro model of normal and cancerous cervical tissue. Methods: Normal epithelial and immortalized cervical epithelial carcinoma cell lines were used to construct 3-D artificial normal cervical and cervical cancerous tissues. De-epidermised dermis (DED) was used as a scaffold for both models. Morphological analyses were conducted by using haematoxylin and eosin staining and characteristics of the models were studied by analysing the expression of different structural cytokeratins and differential protein marker Mad1 using immunohistochemical technique. Results: Haematoxylin and eosin staining results showed that normal cervical tissue had multi epithelial layers while cancerous cervical tissue showed dysplastic changes. Immunohistochemistry staining results revealed that for normal cervix model cytokeratin 10 was expressed in the upper stratified layer of epithelium while cytokeratin 5 was expressed mainly in the middle and basal layer. Cytokeratin 19 was weakly expressed in a few basal cells. Cervical cancer model showed cytokeratin 19 expression in different epithelial layers and weak or no expression for cytokeratin 5 and cytokeratin 10. Mad1 expression was detected in some suprabasal cells. Conclusions: The 3-D in vitro models showed stratified epithelial layers and expressed the same types and patterns of differentiation marker proteins as seen in corresponding in vivo tissue in either normal cervical or cervical cancerous tissue. Findings imply that they can serve as functional normal and cervical cancer models

Life Satisfaction and Sense of Coherence of Breast Cancer Survivors Compared to Women with Mental Depression, Arterial Hypertension and Healthy Controls

The purpose of the study was to compare the life satisfaction (LS) and sense of coherence (SOC) of women recovering from breast cancer (BC) to LS and SOC of women with depression or hypertension and of healthy controls. Finnish Health and Social Support (HeSSup) follow-up survey data in 2003 was linked with national health registries. BC patients were followed up for mortality until the end of 2012. The statistical computations were carried out with SAS (R). There were no significant differences in LS and SOC between the groups with BC, arterial hypertension or healthy controls. Women recovering from BC are as satisfied with their life as healthy controls, and their perceived LS is better and SOC is stronger compared to women with depression. SOC correlated positively (r(2) = 0.36, p <0.001) with LS. However, more studies on determinants of the LS are needed for designing and organizing health care services for BC survivors.Peer reviewe