A polynomial oracle-time algorithm for convex integer minimization

In this paper we consider the solution of certain convex integer minimization problems via greedy augmentation procedures. We show that a greedy augmentation procedure that employs only directions from certain Graver bases needs only polynomially many augmentation steps to solve the given problem. We extend these results to convex $N$-fold integer minimization problems and to convex 2-stage stochastic integer minimization problems. Finally, we present some applications of convex $N$-fold integer minimization problems for which our approach provides polynomial time solution algorithms.Comment: 19 pages, 1 figur

Prediction of near field overpressure from quarry blasting

This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and the polar coordinates of the position of interest (distance to the source and azimuth with respect to the free face). The model has been fitted to empirical data using linear least squares. The data set is composed of 122 airblast records monitored at distances less than 400 m in 41 production blasts carried out in two quarries. The model is statistically significant and has a determination coefficient of 0.87. The formula is validated from 12 airblast measurements gathered in five additional blasts

A New Look at Mode Conversion in a Stratified Isothermal Atmosphere

Recent numerical investigations of wave propagation near coronal magnetic null points (McLaughlin and Hood: Astron. Astrophys. 459, 641,2006) have indicated how a fast MHD wave partially converts into a slow MHD wave as the disturbance passes from a low-beta plasma to a high-beta plasma. This is a complex process and a clear understanding of the conversion mechanism requires the detailed investigation of a simpler model. An investigation of mode conversion in a stratified, isothermal atmosphere, with a uniform, vertical magnetic field is carried out, both numerically and analytically. In contrast to previous investigations of upward-propagating waves (Zhugzhda and Dzhalilov: Astron. Astrophys. 112, 16, 1982a; Cally: Astrophys. J. 548, 473, 2001), this paper studies the downward propagation of waves from a low-beta to high-beta environment. A simple expression for the amplitude of the transmitted wave is compared with the numerical solution.Comment: 14 pages, 6 figure

Genus expansion for real Wishart matrices

We present an exact formula for moments and cumulants of several real compound Wishart matrices in terms of an Euler characteristic expansion, similar to the genus expansion for complex random matrices. We consider their asymptotic values in the large matrix limit: as in a genus expansion, the terms which survive in the large matrix limit are those with the greatest Euler characteristic, that is, either spheres or collections of spheres. This topological construction motivates an algebraic expression for the moments and cumulants in terms of the symmetric group. We examine the combinatorial properties distinguishing the leading order terms. By considering higher cumulants, we give a central limit-type theorem for the asymptotic distribution around the expected value

Comparative effectiveness of canagliflozin, SGLT2 inhibitors and non-SGLT2 inhibitors on the risk of hospitalization for heart failure and amputation in patients with type 2 diabetes mellitus: A real-world meta-analysis of 4 observational databases (OBSERVE-4D)

Aims: Sodium glucose co-transporter 2 inhibitors (SGLT2i) are indicated for treatment of type 2 diabetes mellitus (T2DM)some SGLT2i have reported cardiovascular benefit, and some have reported risk of below-knee lower extremity (BKLE) amputation. This study examined the real-world comparative effectiveness within the SGLT2i class and compared with non-SGLT2i antihyperglycaemic agents. Materials and methods: Data from 4 large US administrative claims databases were used to characterize risk and provide population-level estimates of canagliflozin's effects on hospitalization for heart failure (HHF) and BKLE amputation vs other SGLT2i and non-SGLT2i in T2DM patients. Comparative analyses using a propensity score–adjusted new-user cohort design examined relative hazards of outcomes across all new users and a subpopulation with established cardiovascular disease. Results: Across the 4 databases (142 800 new users of canagliflozin, 110 897 new users of other SGLT2i, 460 885 new users of non-SGLT2i), the meta-analytic hazard ratio estimate for HHF with canagliflozin vs non-SGLT2i was 0.39 (95% CI, 0.26-0.60) in the on-treatment analysis. The estimate for BKLE amputation with canagliflozin vs non-SGLT2i was 0.75 (95% CI, 0.40-1.41) in the on-treatment analysis and 1.01 (95% CI, 0.93-1.10) in the intent-to-treat analysis. Effects in the subpopulation with established cardiovascular disease were similar for both outcomes. No consistent differences were observed between canagliflozin and other SGLT2i. Conclusions: In this large comprehensive analysis, canagliflozin and other SGLT2i demonstrated HHF benefits consistent with clinical trial data, but showed no increased risk of BKLE amputation vs non-SGLT2i. HHF and BKLE amputation results were similar in the subpopulation with established cardiovascular disease. This study helps further characterize the potential benefits and harms of SGLT2i in routine clinical practice to complement evidence from clinical trials and prior observational studies

Impact of Seawater Inorganic Carbon Chemistry on Element Incorporation in Foraminiferal Shell Carbonate

Reconstruction of the marine inorganic carbon system relies on proxy signal carriers, such as element/calcium (El/Ca) ratios in foraminiferal shells. Concentrations of boron, lithium, strontium, and sulfur have been shown to vary with carbonate system parameters, but when comparing individual proxy reconstructions based on these elements, they are rarely in complete agreement. This is likely caused by the simultaneous effects of multiple environmental factors on element incorporation. Culture experiments with benthic foraminifera have revealed that the shell's S/Ca reflects the carbon chemistry and can potentially be used as a proxy for seawater [(Formula presented.)]. Aiming to investigate the application potential of sulfur incorporation for carbonate speciation reconstruction, we present S/Ca ratios in five planktonic foraminiferal species, namely Globigerina bulloides, Globigerinoides ruber albus, Globigerinoides ruber ruber, Trilobatus sacculifer, and Neogloboquadrina incompta from core-top sediments in regions with contrasting [(Formula presented.)], [(Formula presented.)], temperature, and salinity. Analyses of B/Ca and Mg/Ca ratios are included here since these elements have been shown to depend to a certain degree on carbon system parameters (e.g., calcite saturation state and pH, respectively) as well. Moreover, foraminiferal Mg/Ca values covary with S/Ca values and thereby might compromise its proxy application. In contrast to previously published results, this new data set shows a positive correlation between the incorporation of sulfur in the foraminifer's shell and seawater [(Formula presented.)]. As the incorporation of sulfur and magnesium are positively correlated, S/Mg values of the same foraminifera may be used to improve inorganic carbon system reconstructions

Prospects for asteroseismology

The observational basis for asteroseismology is being dramatically strengthened, through more than two years of data from the CoRoT satellite, the flood of data coming from the Kepler mission and, in the slightly longer term, from dedicated ground-based facilities. Our ability to utilize these data depends on further development of techniques for basic data analysis, as well as on an improved understanding of the relation between the observed frequencies and the underlying properties of the stars. Also, stellar modelling must be further developed, to match the increasing diagnostic potential of the data. Here we discuss some aspects of data interpretation and modelling, focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space Sci., in the press Revision: correcting abscissa labels on Figs 1 and

Creating the cultures of the future: cultural strategy, policy and institutions in Gramsci. Part one: Gramsci and cultural policy studies: some methodological reflections

Gramsci’s writings have rarely been discussed and used systematically by scholars in cultural policy studies, despite the fact that in cultural studies, from which the field emerged, Gramsci has been a major source of theoretical concepts. Cultural policy studies were, in fact, theorised as an anti-Gramscian project between the late 1980s and the early 1990s, when a group of scholars based in Australia advocated a major political and theoretical reorientation of cultural studies away from hegemony theory and radical politicisation, and towards reformist-technocratic engagement with the policy concerns of contemporary government and business. Their criticism of the ‘Gramscian tradition’ as inadequate for the study of cultural policy and institutions has remained largely unexamined in any detail for almost twenty years and seems to have had a significant role in the subsequent neglect of Gramsci’s contribution in this area of study. This essay, consisting of three parts, is an attempt to challenge such criticism and to provide an analysis of Gramsci’s writings, with the aim of proposing a more systematic contribution of his work to the theoretical development of cultural policy studies. In Part One, I question the use of the notion of ‘Gramscian tradition’ made by its critics and challenge the claim that it was inadequate for the study of cultural policy and institutions. In parts Two and Three, I consider Gramsci’s specific writings on questions of cultural strategy, policy and institutions, which have so far been overlooked by scholars, arguing that they provide further analytical insights to those offered by his more general concepts. More specifically, in Part Two, I consider Gramsci’s pre-prison writings and political practice in relation to questions of cultural strategy and institutions. I argue that the analysis of these early texts, which were written in the years in which Gramsci was active in party organisation and leadership, is fundamental not only for understanding the nature of Gramsci’s early and continued involvement with questions of cultural strategy and institutions, but also as a key for deciphering and interpreting cultural policy themes that he later developed in the prison notebooks, and which originated in earlier debates. Finally, in Part Three, I carry out a detailed analysis of Gramsci’s prison notes on questions of cultural strategy, policy and institutions, which enrich the theoretical underpinnings for critical frameworks of analysis as well as for radical practices of cultural strategy, cultural policy-making and cultural organisation. I then answer the question of whether Gramsci’s insights amount to a theory of cultural policy

An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types