Polynomial expansion and sublinear separators

Let $\mathcal{C}$ be a class of graphs that is closed under taking subgraphs. We prove that if for some fixed $0<\delta\le 1$, every $n$-vertex graph of $\mathcal{C}$ has a balanced separator of order $O(n^{1-\delta})$, then any depth-$k$ minor (i.e. minor obtained by contracting disjoint subgraphs of radius at most $k$) of a graph in $\mathcal{C}$ has average degree $O\big((k \text{ polylog }k)^{1/\delta}\big)$. This confirms a conjecture of Dvo\v{r}\'ak and Norin.Comment: 6 pages, no figur

Neutron scattering studies on URu2Si2

This paper is aiming to review some of the neutron scattering studies performed on URu2Si2 in Grenoble. This compound has been studied for a quarter of century because of a so-called hidden order ground state visible by most of the bulk experiments but almost invisible by microscopic probes like neutrons, muons NMR or x-ray. We stress on some aspects that were not addressed previously. Firstly, the comparison of the cell parameters in the 1-2-2 systems seems to point that the magnetic properties of URu2Si2 are leading by an U4+ electronic state. Secondly, a compilation of the different studies of the tiny antiferromagnetic moment indicates that the tiny antiferromagnetic moment has a constant value which may indicate that it is not necessary extrinsic. We also present the last development on the magnetic form factor measurement in which the magnetic density rotates when entering in the hidden order state. To end, the thermal dependence of the two most intense magnetic excitation at Q0=(1,0,0) and Q1=(0.6,0,0) seems to indicate two different origins or processes for these excitations.Comment: 18 pages, 18 figures, published in Philosophical Magazine, 201

The construction and evaluation of a series of exercises in creative drama

Thesis (Ed.D.)--Boston University

The ultrasonic production of cavitation in liquids

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

United States Air Force Aero Club Management by Break-even Analysis

The problem to be examined in this research effort is whether or not it is possible to provide aero club management with simple, effective, easily applied methods for making financial decisions which will make them self-supporting while meeting the flying demands of their members. The objectives of the study are: 1. Determine a satisfactory means for determining costs and charging flying rates to maintain aero clubs in a financially solvent status. 2. Determine the types of information needed to assist aero club management in achieving the first objective. The procedures developed and concepts employed for the Ellsworth Club model are adaptable for use by all aero clubs. The available regulations and manuals in print on United States Air Force Aero Club management define goals, and guidelines for accounting procedures for use by aero club administration. Management talents and know-how are assumed to be available through the personnel who are selected to direct each club. If qualified individuals are not available, clubs are in danger of closing. The methods described 1n this study should provide adequate guidance to assist conscientious managers in making sound decisions. Given the assumption of the Air Force that individuals associated with flying, as they are in the Air Force, will have a desire to engage in flying activities. The management of aero club resources is an economic activity directed toward the goal of satisfying human wants--that of participating in flying activities. This study will employ economic methods useful to aero club management in choosing types and quantities of flying activities to be produced by each club. It is the proper selection of aircraft, rates, and types of flying that are the basis of aero club activities and, therefore, determine the financial stability of a club and its capability to support itself

ESSENTIAL CHARACTERISTICS OF AN ERP SYSTEM: CONCEPTUALIZATION AND OPERATIONALIZATION

The interest of firms in ERP systems has been echoed in both the scientific and professional literature. It is worth noting however that while this literature has become increasingly abundant, there does not yet exist an operational definition of the ERP concept that is, if not unanimously, at least widely accepted. This constitutes a handicap for both the research and practice communities. The present study outlines what could be considered as an ERP by first determining the essentially required characteristics of such a system: integration, flexibility and transversality. Indicators are then provided in order to operationalise these three characteristics. The study concludes by proposing a research framework on the impact of an ERP’s key characteristics upon the performance of the system in a given organisational setting