A topological approach to the problem of searching on a contour map

Topological approach to obtain ground track of aircraft using height over terrain and contour ma

Larvae of the three common North American species of Phylocentropus (Trichoptera: Dipseudopsidae)

The caddisfly genus Phylocentropus includes 7 extant species globally, of which 5 occur in eastern North America and 2 in eastern Asia. Larvae of the 3 most common North American species [Phylocentropus carolinus Carpenter, P. lucidus (Hagen), and P. placidus (Banks)] were associated with identifiable adults and diagnostic characters are described. Larvae ofthese 3 species may be distinguished by overall length of mature larvae, head color pattern, and number of spines on the hind tibiae. Larvae of other species of this genus are unknown

Materials and construction techniques for cryogenic wind tunnel facilities for instruction/research use

The results of the cryogenic wind tunnel program conducted at NASA Langley Research Center are presented to provide a starting point for the design of an instructional/research wind tunnel facility. The advantages of the cryogenic concept are discussed, and operating envelopes for a representative facility are presented to indicate the range and mode of operation. Special attention is given to the design, construction and materials problems peculiar to cryogenic wind tunnels. The control system for operation of a cryogenic tunnel is considered, and a portion of a linearized mathematical model is developed for determining the tunnel dynamic characteristics

Distance and intersection number in the curve graph of a surface

In this work, we study the cellular decomposition of $S$ induced by a filling pair of curves $v$ and $w$, $Dec_{v,w}(S) = S - (v \cup w)$, and its connection to the distance function $d(v,w)$ in the curve graph of a closed orientable surface $S$ of genus $g$. Efficient geodesics were introduced by the first author in joint work with Margalit and Menasco in 2016, giving an algorithm that begins with a pair of non-separating filling curves that determine vertices $(v,w)$ in the curve graph of a closed orientable surface $S$ and computing from them a finite set of {\it efficient} geodesics. We extend the tools of efficient geodesics to study the relationship between distance $d(v,w)$, intersection number $i(v,w)$, and $Dec_{v,w}(S)$. The main result is the development and analysis of particular configurations of rectangles in $Dec_{v,w}(S)$ called \textit{spirals}. We are able to show that, in some special cases, the efficient geodesic algorithm can be used to build an algorithm that reduces $i(v,w)$ while preserving $d(v,w)$. At the end of the paper, we note a connection of our work to the notion of extending geodesics.Comment: 20 pages, 17 figures. Changes: A key lemma (Lemma 5.6) was revised to be more precise, an irrelevant proposition (Proposition 2.1) and example were removed, unnecessary background material was taken out, some of the definitions and cited results were clarified (including added figures,) and Proposition 5.7 and Theorem 5.8 have been merged into a single theorem, Theorem 4.

A Hybrid Observer for a Distributed Linear System with a Changing Neighbor Graph

A hybrid observer is described for estimating the state of an $m>0$ channel, $n$-dimensional, continuous-time, distributed linear system of the form $\dot{x} = Ax,\;y_i = C_ix,\;i\in\{1,2,\ldots, m\}$. The system's state $x$ is simultaneously estimated by $m$ agents assuming each agent $i$ senses $y_i$ and receives appropriately defined data from each of its current neighbors. Neighbor relations are characterized by a time-varying directed graph $\mathbb{N}(t)$ whose vertices correspond to agents and whose arcs depict neighbor relations. Agent $i$ updates its estimate $x_i$ of $x$ at "event times" $t_1,t_2,\ldots$ using a local observer and a local parameter estimator. The local observer is a continuous time linear system whose input is $y_i$ and whose output $w_i$ is an asymptotically correct estimate of $L_ix$ where $L_i$ a matrix with kernel equaling the unobservable space of $(C_i,A)$. The local parameter estimator is a recursive algorithm designed to estimate, prior to each event time $t_j$, a constant parameter $p_j$ which satisfies the linear equations $w_k(t_j-\tau) = L_kp_j+\mu_k(t_j-\tau),\;k\in\{1,2,\ldots,m\}$, where $\tau$ is a small positive constant and $\mu_k$ is the state estimation error of local observer $k$. Agent $i$ accomplishes this by iterating its parameter estimator state $z_i$, $q$ times within the interval $[t_j-\tau, t_j)$, and by making use of the state of each of its neighbors' parameter estimators at each iteration. The updated value of $x_i$ at event time $t_j$ is then $x_i(t_j) = e^{A\tau}z_i(q)$. Subject to the assumptions that (i) the neighbor graph $\mathbb{N}(t)$ is strongly connected for all time, (ii) the system whose state is to be estimated is jointly observable, (iii) $q$ is sufficiently large, it is shown that each estimate $x_i$ converges to $x$ exponentially fast as $t\rightarrow \infty$ at a rate which can be controlled.Comment: 7 pages, the 56th IEEE Conference on Decision and Contro

Factors in the emergence of infectious diseases.

"Emerging" infectious diseases can be defined as infections that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range. Among recent examples are HIV/AIDS, hantavirus pulmonary syndrome, Lyme disease, and hemolytic uremic syndrome (a foodborne infection caused by certain strains of Escherichia coli). Specific factors precipitating disease emergence can be identified in virtually all cases. These include ecological, environmental, or demographic factors that place people at increased contact with a previously unfamiliar microbe or its natural host or promote dissemination. These factors are increasing in prevalence; this increase, together with the ongoing evolution of viral and microbial variants and selection for drug resistance, suggests that infections will continue to emerge and probably increase and emphasizes the urgent need for effective surveillance and control. Dr. David Satcher's article and this overview inaugurate Perspectives, a regular section in this journal intended to present and develop unifying concepts and strategies for considering emerging infections and their underlying factors. The editors welcome, as contributions to the Perspectives section, overviews, syntheses, and case studies that shed light on how and why infections emerge, and how they may be anticipated and prevented

Limits of stakeholder participation in sustainable development : "where facts are few, experts are many"

Extract from: The Mediterranean coastal areas from watershed to the sea : interactions and changes / by L.F. Cassar ... [et al.]. Proceedings of the MEDCORE International conference, Florence, 10th-14th November 2005The notion of including stakeholders, those affected (positively or negatively) by a sustainable development programme in both its design and implementation, has become a central concern for those implementing such programmes. Such an approach is often referred to as ‘stakeholder participation’, as ‘participatory development’ or more simply still as ‘participation’. How best to achieve this has been the topic of a substantial literature, with a host of different methodologies presented and promoted. Each has its own advantages and disadvantages, but there has been surprisingly little discussion in the sustainable development literature as to the limits and dangers of participation irrespective of the approach employed to ‘best’ facilitate it. Inter-linked with the limits of participation is the role of specialists and expert opinion in sustainable development. This paper discusses the results of participatory exercises conducted in Gozo (Malta) between 2003 and 2005. On the positive side, participation yielded many useful and interesting insights and invoked a sense of ‘involvement’ in sustainable development, but there were problems and these are discussed in this paper. For example, the outcome of the exercise crucially depends upon representation, and a simplified vision of ‘community’ often employed in participation to make it practicable can load the process in favour of certain stakeholder groups at the expense of others.peer-reviewe

Effect of temperature and relative humidity on the development times and survival of Synopsyllus fonquerniei and Xenopsylla cheopis, the flea vectors of plague in Madagascar

Acknowledgements We would like to thank Dr Lila Rahalison and Jocelyn Ratovonjato for their advice and help during the experiment. We are grateful to the staff of the Plague Unit and the Medical Entomology Unit at the Institut Pasteur de Madagascar, particularly Dr Nohal Elissa. Without their expertise this study would not have been possible. Sincere thanks to Mr Tojo Ramihangihajason for his technical assistance. We are indebted to the Institut Pasteur de Madagascar for an internal grant which facilitated additional laboratory research. Two Wellcome Trust fellowships supported ST during this work (081705 and 095171).Peer reviewedPublisher PD

An approach to comparing external and internal methods for analysing group dynamic

Beginning with the question, can a multi-methodology explore the nature of group work from both the inside out (group participant self-analysis) and the outside in (facilitator observed analysis), this paper presents the results of a statistical analysis comparing two different approaches to assessing group function: SYMLOG (A SYstem for the Multiple Level Observation of Groups) and BECM (Being, Engaging, Contextualising and Managing). SYMLOG is a quantitative internal assessment of group function made by members of the group, while BECM is qualitative external assessment made by an outsider observing the groups. Together, it is argued, they provide a unique, triangulated assessment of the group dynamic. By employing a ‘best subsets’ linear regression technique it was found that some of the 26 characteristics of SYMLOG are related to BECM scoring (adjusted R2 = 0.82). The paper discusses the reasons for this and the repercussions for such blending of approaches to understanding group dynamic. The paper ends by discussing the relative advantages and disadvantages of the two approaches and potential for further hybridising of them in blended group dynamic approaches