Structured analysis and modeling of complex systems

The Aircrew Evaluation Sustained Operations Performance (AESOP) facility at Brooks AFB, Texas, combines the realism of an operational environment with the control of a research laboratory. In recent studies we collected extensive data from the Airborne Warning and Control Systems (AWACS) Weapons Directors subjected to high and low workload Defensive Counter Air Scenarios. A critical and complex task in this environment involves committing a friendly fighter against a hostile fighter. Structured Analysis and Design techniques and computer modeling systems were applied to this task as tools for analyzing subject performance and workload. This technology is being transferred to the Man-Systems Division of NASA Johnson Space Center for application to complex mission related tasks, such as manipulating the Shuttle grappler arm

Postmortem Evaluation of Left Flank Laparoscopic Access in an Adult Female Giraffe (Giraffa camelopardalis)

There are still few reports of laparoscopy in megavertebrates. The giraffe (Giraffa camelopardalis) is the tallest land mammal, and the largest ruminant species. An 18-year-old multiparous female hybrid giraffe, weighing 650 kg, was euthanized for chronic health problems, and left flank laparoscopy was performed less than 30 minutes after death. Safe primary access was achieved under visualisation using an optical bladed trocar (Visiport Plus, Tyco healthcare UK Ltd) without prior abdominal insufflation. A left paralumbar fossa approach allowed access to the spleen, rumen, left kidney, and intestines, but did not allow access to the reproductive tract which in nongravid females is intrapelvic in nature

The World Bank, the Grant Program, and the CGIAR: A Retrospective Review

A paper published as OED Working Paper Series No. 1 by the Operations Evaluation Department of the World Bank. It was prepared by Jock Anderson of the Bank and Dana Dalrymple of USAID as background for an OED study of the Bank's Special Grant Program, which is the source of the World Bank contribution to the CGIAR. The paper describes the CGIAR, its role in development, and the involvement of the World Bank in the CGIAR. A chapter analyzes the planning, review and evaluation process of the CGIAR, and others assess the Group's achievements and the constraints and challenges that it faces. There is an assessment both of the performance of the CGIAR and its centers, and of the World Bank and other donors. The authors conclude that the CGIAR System cannot be taken for granted and requires close attention.There are annexes on World Bank contributions to agricultural research centers not affiliated with the CGIAR and to the Special Program on African Agricultural Research (SPAAR)

Modeling dam break behavior over a wet bed by a SPH technique

Dam break evolution over dry and wet beds is analyzed with a smoothed particle hydrodynamics model. The model is shown to accurately fit both experimental dam break profiles and the measured velocities. In addition, the model allows one to study different propagation regimes during the dam break evolution. In particular, different dissipation mechanisms were identified: bottom friction and wave breaking. Although breaking dominates over wet beds at the beginning of the movement, bottom friction becomes the main dissipation mechanism in the long run

Culture, role and group work: A Social network analysis perspective on an online collaborative course

This paper discusses the patterns of network dynamics within a multicultural online collaborative learning environment. It analyses the interaction of participants (both students and facilitators) within a discussion board that was established as part of a 3-month online collaborative course. The study employs longitudinal probabilistic social network analysis (SNA) to identify the patterns and trends within the network. It conjectures and tests a set of hypotheses concerning the tendencies towards homophily/heterophily and preferential attachment. The paper presents identified interaction network patterns in relation to cultural differences. It also evaluates network dynamics by considering participant roles and group work in the course under study. Results of social network analyses are reported along with measures of statistical confidence in findings. The potential for extending exploratory SNA methods and visualisation techniques in educational research are discussed here

Age of the Peach Springs Tuff, Southeastern California and Western Arizona

Sanidine separates from pumice of the early Miocene Peach Springs Tuff are concordantly dated at 18.5 ± 0.2 Ma by two isotopic techniques. The Peach Springs Tuff is the only known unit that can be correlated between isolated outcrops of Miocene strata from the central Mojave Desert of southeastern California to the western Colorado Plateau in Arizona, across five structural provinces, a distance of 350 km. Thus the age of the Peach Springs Tuff is important to structural and paleogeographic reconstructions of a large region. Biotite and sanidine separates from bulk samples of the Peach Springs Tuff from zones of welding and vapor-phase alteration have not produced consistent ages by the K-Ar method. Published ages of mineral separates from 17 localities ranged from 16.2 to 20.5 Ma. Discordant 40Ar/39Ar incremental release spectra were obtained for one biotite and two of the sanidine separates. Ages that correspond to the last gas increments are as old as 27 Ma. The 40Ar/39Ar incremental release determinations on sanidine separated from blocks of Peach Springs Tuff pumice yield ages of 18.3 ± 0.3 and 18.6 ± 0.4 Ma. Laser fusion measurements yield a mean age of 18.51 ± 0.10. The results suggest that sanidine and biotite K-Ar ages older than about 18.5 Ma are due to inherited Ar from pre-Tertiary contaminants, which likely were incorporated into the tuff during deposition. Sanidine K-Ar ages younger than 18 Ma probably indicate incomplete extraction of radiogenic 40Ar, whereas laser fusion dates of biotite and hornblende younger than 18 Ma likely are due to postdepositional alteration. Laser fusion ages as high as 19.01 Ma on biotite grains from pumice suggest that minerals from pre-Tertiary country rocks also were incorporated in the magma chamber

Projective Identification and the Fear of Failing: Making Sense of Practice Educators' Experiences of Failing Social Work Students in Practice Learning Settings

The study focuses on emotional processes that may arise for practice educators when working with struggling or failing students in practice learning settings. Informed by a thematic review of the literature exploring the phenomenon of ‘failing to fail’, the study draws on two UK qualitative studies that highlighted the emotional distress experienced by practice educators when working with a marginal or failing student. The study draws key examples from these prior studies and argues that the psychoanalytic concept of projective identification offers a plausible and illuminating account of the states of mind experienced and reported by some practice educators in the ‘failing to fail’ dilemma. The notion is proffered as a conceptual framework for practice educators to explore and apply to their own practice as a means of making explicit unconscious states of mind, helping to recognise and rationalise these, thus supporting confidence in making appropriate assessment decisions

Nontangential limits and Fatou-type theorems on post-critically finite self-similar sets

In this paper we study the boundary limit properties of harmonic functions on $\mathbb R_+\times K$, the solutions $u(t,x)$ to the Poisson equation $$\frac{\partial^2 u}{\partial t^2} + \Delta u = 0,$$ where $K$ is a p.c.f. set and $\Delta$ its Laplacian given by a regular harmonic structure. In particular, we prove the existence of nontangential limits of the corresponding Poisson integrals, and the analogous results of the classical Fatou theorems for bounded and nontangentially bounded harmonic functions.Comment: 22 page