Bisecting binomial coefficients

In this paper, we deal with the problem of bisecting binomial coefficients. We find many (previously unknown) infinite classes of integers which admit nontrivial bisections, and a class with only trivial bisections. As a byproduct of this last construction, we show conjectures Q2 and Q4 of Cusick and Li [7]. We next find several bounds for the number of nontrivial bisections and further compute (using a supercomputer) the exact number of such bisections for n ≤ 51

Dynamics of probability density functions for decaying passive scalars in periodic velocity fields

The probability density function (PDF) for a decaying passive scalar advected by a deterministic, periodic, incompressible fluid flow is numerically studied using a variety of random and coherent initial scalar fields. We establish the dynamic emergence at large Péclet num-bers of a broad-tailed PDF for the scalar initialized with a Gaussian random measure, and further explore a rich parameter space involv-ing scales of the initial scalar field and the geometry of the flow. We document that the dynamic transition of the PDF to a broad tailed distribution is similar for shear flows and time-varying non-sheared flows with positive Lyapunov exponent, thereby showing that chaos in the particle trajectories is not essential to observe intermittent scalar signals. The role of the initial scalar field is carefully explored. The long time PDF is sensitive to the scale of the initial data. For shear flows we show that heavy-tailed PDFs appear only when the initial field has sufficiently small-scale variation. We also connect geometric features of the scalar field with the shape of the PDFs. We docu-ment that the PDF is constructed by a subtle balance between spatial regions of strong and weak shear in conjunction with the presence of 1 To appear: Physics of Fluids small-scale scalar variation within the weak shear regions. For cellular flows we document a lack of self-similarity in the PDFs when periodic time dependence is present, in contrast to the self-similar decay for time independent flow. Finally we analyze the behavior of the PDFs for coherent initial fields and the parametric dependence of the vari-ance decay rate on the Péclet number and the initial wavenumber of the scalar field. 2

Soil organic carbon and associated soil properties in Enset (Ensete ventricosum Welw. Cheesman)-based homegardens in Ethiopia

Enset (Ensete ventricosum Welw. Cheesman)-based homegardens have long been practiced as central elements of agricultural land management and food security in south and southwest Ethiopia. In contrast to the homegardens’ biodiversity and role in food security, soil quality has received little attention. Objective of this study was to assess soil quality parameters in typical homegardens in comparison with adjacent croplands, both under continuous management for >30 years. The study was undertaken at high (2200–2330 masl), mid (1799–1849 masl), and low (1349–1381 masl) elevation in the central Omo-Gibe basin, southwest Ethiopia. Through interviews of 49 randomly selected farm households, and soil sampling at six paired sites at high and mid elevations, and five paired sites of low elevation, we found that homegardens received the majority of household waste and manure and were less frequently tilled. By contrast, some, but not all, croplands occasionally received inorganic fertilizer. Homegarden soil had significantly greater (P < 0.05) soil organic carbon (SOC) concentrations than croplands. At 0–20 cm depth, SOC concentrations in homegardens (22.4–26.4 mg

Convergence towards a European strategic culture? A constructivist framework for explaining changing norms.

The article contributes to the debate about the emergence of a European strategic culture to underpin a European Security and Defence Policy. Noting both conceptual and empirical weaknesses in the literature, the article disaggregates the concept of strategic culture and focuses on four types of norms concerning the means and ends for the use of force. The study argues that national strategic cultures are less resistant to change than commonly thought and that they have been subject to three types of learning pressures since 1989: changing threat perceptions, institutional socialization, and mediatized crisis learning. The combined effect of these mechanisms would be a process of convergence with regard to strategic norms prevalent in current EU countries. If the outlined hypotheses can be substantiated by further research the implications for ESDP are positive, especially if the EU acts cautiously in those cases which involve norms that are not yet sufficiently shared across countries

Photochromic mechanism in oxygen-containing yttrium hydride thin films: An optical perspective

Oxygen-containing yttrium hydride thin films exhibit photochromic behavior: Transparent thin films reversibly switch from a transparent state to a photodarkened state after being illuminated with UV or blue light. From optical spectrophotometry and ellipsometry measurements of the transparent state and photodarkened state, it is concluded that the photochromic effect can be explained by the gradual growth, under illumination, of metallic domains within the initial wide-band-gap semiconducting lattice. This conclusion is supported by Raman measurements

Procedural and long-term ischemic outcomes of tight subtotal occlusions treated with orbital atherectomy: An ORBIT II subanalysis

Background/purpose Orbital atherectomy is an effective treatment strategy to modify severely calcified coronary lesions prior to stent placement. Traversing a severely calcified subtotal occlusion with the crown may be more challenging compared with a less severely stenotic lesion. The purpose of this ORBIT II subanalysis was to evaluate outcomes post-orbital atherectomy (OA) treatment of lesions with ≥95% stenosis. Methods/materials ORBIT II, a single-arm, prospective, multicenter trial, enrolled 443 subjects with severely calcified coronary lesions. Patients with chronic total occlusions were excluded from the trial. Subjects with the OA device activated were stratified based on pre-procedure percent stenosis: ≥95% stenosis (N = 91) and <95% stenosis (N = 341). Procedural success and 3-year major adverse cardiac event (MACE) rates were compared. Results The severe angiographic complications rates were 6.6% and 6.7% in the ≥95% and <95% stenosis groups, respectively. There was no significant difference in procedural success (94.5% vs. 88.3%, p = 0.120). 3-year MACE rates were similar (27.1% vs. 22.5%, p = 0.548), as were the rates of cardiac death (5.7% vs. 7.1%, p = 0.665) and MI (7.9% vs. 12.1%, p = 0.244). The TVR rate was higher in the ≥95% stenosis group (19.1% vs. 7.5%, p = 0.004). Conclusions In ORBIT II, OA treatment of lesions with ≥95% stenosis resulted in a high rate of procedural success. Although the 3-year revascularization rate was higher in the ≥95% stenosis group, it is not unexpected given the challenge of treating such complex lesions. The results of this analysis suggest that OA may be a reasonable treatment strategy for tight, severely calcified subtotal occlusions. Summary The purpose of this ORBIT II subanalysis was to evaluate outcomes post-orbital atherectomy (OA) treatment of lesions with ≥95% stenosis. In ORBIT II, OA treatment of lesions with ≥95% stenosis resulted in a high rate of procedural success. Although the 3-year revascularization rate was higher in the ≥95% stenosis group, it is not unexpected given the challenge of treating such complex lesions. The results of this analysis suggest that OA may be a reasonable treatment strategy for tight, severely calcified subtotal occlusions

The polyphyly of Plasmodium: Comprehensive phylogenetic analyses of the malaria parasites (Order Haemosporida) reveal widespread taxonomic conflict

© 2018 The Authors. The evolutionary relationships among the apicomplexan blood pathogens known as the malaria parasites (order Haemosporida), some of which infect nearly 200 million humans each year, has remained a vexing phylogenetic problem due to limitations in taxon sampling, character sampling and the extreme nucleotide base composition biases that are characteristic of this clade. Previous phylogenetic work on the malaria parasites has often lacked sufficient representation of the broad taxonomic diversity within the Haemosporida or the multi-locus sequence data needed to resolve deep evolutionary relationships, rendering our understanding of haemosporidian lifehistory evolution and the origin of the human malaria parasites incomplete. Here we present the most comprehensive phylogenetic analysis of the malaria parasites conducted to date, using samples from a broad diversity of vertebrate hosts that includes numerous enigmatic and poorly known haemosporidian lineages in addition to genome-wide multi-locus sequence data. We find that if base composition differences were corrected for during phylogenetic analysis, we recovered a well-supported topology indicating that the evolutionary history of the malaria parasites was characterized by a complex series of transitions in life-history strategies and host usage. Notably we find that Plasmodium, the malaria parasite genus that includes the species of human medical concern, is polyphyletic with the life-history traits characteristic of this genus having evolved in a dynamic manner across the phylogeny. We find support for multiple instances of gain and loss of asexual proliferation in host blood cells and production of haemozoin pigment, two traits that have been used for taxonomic classification as well as considered to be important factors for parasite virulence and used as drug targets. Lastly, our analysis illustrates the need for a widespread reassessment of malaria parasite taxonomy