Research requirements for development of regenerative engines for helicopters

The improved specific fuel consumption of the regenerative engine was compared to a simple-cycle turboshaft engine. The performance improvement and fuel saving are obtained at the expense of increased engine weight, development and production costs, and maintenance costs. Costs and schedules are estimated for the elements of the research and development program. Interaction of the regenerative engine with other technology goals for an advanced civil helicopter is examined, including its impact on engine noise, hover and cruise performance, helicopter empty weight, drive-system efficiency and weight, one-engine-inoperative hover capability, and maintenance and reliability

The structure of equivalent 3-separations in a 3-connected matroid

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The structure of 3-connected matroids of path width three

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Fork-decompositions of matroids

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On matroids of branch-width three

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The spatial concentration of domestic and foreign multinational corporate headquarters in Canada

Cet article analyse la concentration spatiale des grandes corporations au Canada et mesure les inégalités régionales dans leur répartition. En plus de la concentration spatiale de ces corporations qui, d'ailleurs, deviennent de plus en plus synonymes de contrôle étranger, nous identifions les secteurs de l'économie réellement dominés.Nous suggérons que les régions qui accueillent les sièges sociaux des corporations multinationales sont les bénéficiaires du pouvoir monétaire, de la puissance politique et des innovations technologiques dont se dotent ces établissements pour faire face à une grande variété de situations économiques et politiques. Si l'on admet qu'une région puisse bénéficier de la présence des grandes corporations, et que celles-ci sont concentrées dans des régions données, il existe la possibilité que certaines régions démunies de ces mêmes avantages, se sentent mises à l'écart du courant général de bien-être caractérisant la nation. Il semble que ce problème de la concentration spatiale et sectorielle des corporations étrangères et domestiques soit l'une des causes multiples qui alimentent le nationalisme et le provincialisme canadiens.This paper examines the spatial concentration of corporate power in Canada and measures the regional imbalances that are presently so noticeable. Furthermore, since corporate power in many instances is becoming ever more synonomous with foreign control the research notes not only the spatial concentration of this control but the sectors of the economy that are effectively under foreign domination.The paper intimates that those areas that house the headquarters of the giant multinational corporation are the net beneficiaries of the monetary strength, political leverage and technical expertise that these establishments have available to bring to bear in a wide variety of economic and political situations. It follows that if an area benefits from the presence of large corporations, and these same corporations are concentrated into particular regions then the possibility arises that certain "have-not" regions will have cause to feel left out of the mainstream of decision making that characterizes the economic and political well being of the entire nation. It appears that this joint problem of spatial concentration and sectoral domination by domestic as well as foreign corporations may be one of the many catalysts fostering both present-day Canadian nationalism and overt provincial sectionalism

The structure of 3-connected matroids of path-width three

A 3-connected matroid M is sequential or has path width 3 if its ground set E(M) has a sequential ordering, that is, an ordering (e₁,e₂,...,en) such that ({e₁,e₂,...,ek},{ek+1,ek+2,...,en}) is a 3-separation for all k in {3,4,...,n-3}. In this paper, we consider the possible sequential orderings that such a matroid can have. In particular, we prove that M essentially has two fixed ends, each of which is a maximal segment, a maximal cosegment, or a maximal fan. We also identify the possible structures in M that account for different sequential orderings of E(M). These results rely on an earlier paper of the authors that describes the structure of equivalent non-sequential 3-separations in a 3-connected matroid. Those results are extended here to describe the structure of equivalent sequential 3-separations

Interurban Corporate Headquarters Relocation in Canada

This study examines the interurban migration of corporate headquarters in Canada for the period 1970-1982 by investigating the premise that changing socio-economic and political conditions are contributing to the relocation of corporate headquarters. The paper demonstrates that in Canada corporate relocations are tending to create a spatially more concentrated location pattern.Cette étude explore la migration interurbaine des sièges sociaux au Canada à partir de 1970 jusqu'en 1982, en examinant le principe que les conditions changeantes, tant sur les plans socio-économique que politique, contribuent au déplacement des sièges sociaux. Cet article démontre qu'au Canada les migrations des sièges sociaux ont tendance à établir un système spatialement plus concentré

Representing Partitions on Trees

In evolutionary biology, biologists often face the problem of constructing a phylogenetic tree on a set X of species from a multiset Π of partitions corresponding to various attributes of these species. One approach that is used to solve this problem is to try instead to associate a tree (or even a network) to the multiset ΣΠ consisting of all those bipartitions {A,X − A} with A a part of some partition in Π. The rational behind this approach is that a phylogenetic tree with leaf set X can be uniquely represented by the set of bipartitions of X induced by its edges. Motivated by these considerations, given a multiset Σ of bipartitions corresponding to a phylogenetic tree on X, in this paper we introduce and study the set P(Σ) consisting of those multisets of partitions Π of X with ΣΠ = Σ. More specifically, we characterize when P(Σ) is non-empty, and also identify some partitions in P(Σ) that are of maximum and minimum size. We also show that it is NP-complete to decide when P(Σ) is non-empty in case Σ is an arbitrary multiset of bipartitions of X. Ultimately, we hope that by gaining a better understanding of the mapping that takes an arbitrary partition system Π to the multiset ΣΠ, we will obtain new insights into the use of median networks and, more generally, split-networks to visualize sets of partitions

‘<i>I didn’t know what was in front of me</i>’ – bereaved parents’ experience of adapting to life when a co-parent of dependent children has died with cancer

OBJECTIVE: It is not clear how the bereaved parent navigates life with the children after a co‐parent has died. The objective of this study is to explore bereaved parents' experience of managing life when a co‐parent of dependent children has died with cancer. METHODS: Twenty‐one in‐depth interviews were conducted with bereaved parents when a co‐parent died with cancer. Data were analysed thematically. RESULTS: Bereaved parents highlighted how their children was their key focus after the death of a co‐parent with cancer, as they effortfully strived to be a ‘perfect parent’. While some bereaved parents struggled to adapt to the role as a sole parent, others described the importance of maximising social networks to help with the practical aspects of parenting. However, most bereaved parents described intense feelings of loneliness as they navigated parenting alone. To help navigate this post‐bereavement period, parents considered it important for their children to openly talk about the deceased parent. Also, meeting others who have experienced similar situations was helpful for the bereaved parent and children, providing hope for the future. Results are discussed under two themes: (1) adapting to life without the parent, and (2) a desire to keep the memory alive of the parent that died with cancer. CONCLUSIONS: Bereaved parents should be encouraged to practice self‐care when a co‐parent has died from cancer so they can appropriately meet the needs of their children. Bereaved parents should be reassured that showing emotion in front of the children is helpful and could facilitate better grief experiences for the whole family