Reviews

A. Barker and F. Manji, Writing for Change ‐ An Interactive Guide to Effective Writing, Writing for Science, Writing for Advocacy, CD‐ROM and Users Guide, Fahama/International Development Research Centre, Oxford, 2000. ISBN: 0–9536–9021–0, no price given. Softback (28 pages) and CD‐ROM

Identification of nonlinear vibrating structures: Part II -- Applications

A time-domain procedure for the identification of nonlinear vibrating structures, presented in a companion paper, is applied to a "calibration" problem which incorporates realistic test situations and nonlinear structural characteristics widely encountered in the applied mechanics field. The "data" set is analyzed to develop suitable, approximate nonlinear system representations. Subsequently, a "validation" test is conducted to demonstrate the range of validity of the method under discussion. It is shown that the procedure furnishes a convenient means for constructing reduced-order nonlinear nonparametric mathematical models of reasonably high fidelity in regard to reproducing the response of the test article under dynamic loads that differ from the identification test loads

Why Are People's Decisions Sometimes Worse with Computer Support?

In many applications of computerised decision support, a recognised source of undesired outcomes is operators' apparent over-reliance on automation. For instance, an operator may fail to react to a potentially dangerous situation because a computer fails to generate an alarm. However, the very use of terms like "over-reliance" betrays possible misunderstandings of these phenomena and their causes, which may lead to ineffective corrective action (e.g. training or procedures that do not counteract all the causes of the apparently "over-reliant" behaviour). We review relevant literature in the area of "automation bias" and describe the diverse mechanisms that may be involved in human errors when using computer support. We discuss these mechanisms, with reference to errors of omission when using "alerting systems", with the help of examples of novel counterintuitive findings we obtained from a case study in a health care application, as well as other examples from the literature

The Challenges of Rural Poverty

In rural America today, more than one in seven residents lives in poverty. Poverty's causes are a complex interplay of individual characteristics and decisions, on the one hand, and the nature of the communities and economies in which people work and live, on the other. Leif Jensen, Diane McLaughlin, and Tim Slack, in their chapter in "Challenges for Rural America in the Twenty-First Century", show how poverty emerges in rural areas and offer suggestions about what can be done to bolster the incomes and well-being of rural residents.This issue brief is a joint product of the Rural Sociological Society and the National Coalition for Rural Entrepreneurship, a collaboration of four Regional Rural Development Centers: The Northeast Regional Center for Rural Development, the Southern Rural Development Center, the North Central Regional Center for Rural Development, and the Western Rural Development Center. Funding was also made available from the Ford Foundation.This brief is part of a policy brief series by the Rural Sociological Society and the Regional Rural Development Centers that stresses the importance of community collective action and developing the capacity of people and organizations to meet the community's needsThe Rural Sociological Society and the Regional Rural Development Centers creates new Public Policy Issue Brief series based on its recent book, "Challenges for Rural America in the Twenty-First Century".The briefs synthesize the context and substance of important issues raised in the book and address alternative policy options, with the goal of bringing important research to the policy community

Self-Diffusion of a Polymer Chain in a Melt

Self-diffusion of a polymer chain in a melt is studied by Monte Carlo simulations of the bond fluctuation model, where only the excluded volume interaction is taken into account. Polymer chains, each of which consists of $N$ segments, are located on an $L \times L \times L$ simple cubic lattice under periodic boundary conditions, where each segment occupies $2 \times 2 \times 2$ unit cells. The results for $N=32, 48, 64, 96, 128, 192, 256, 384$ and 512 at the volume fraction $\phi \simeq 0.5$ are reported, where $L = 128$ for $N \leq 256$ and L=192 for $N \geq 384$. The $N$-dependence of the self-diffusion constant $D$ is examined. Here, $D$ is estimated from the mean square displacements of the center of mass of a single polymer chain at the times larger than the longest relaxation time. From the data for $N = 256$, 384 and 512, the apparent exponent $x_{\rm d}$, which describes the apparent power law dependence of $D$ on $N$ as $D \propto N^{- x_{\rm d}}$, is estimated as $x_{\rm d} \simeq 2.4$. The ratio $D \tau /$ seems to be a constant for $N = 192, 256, 384$ and 512, where $\tau$ and $$ denote the longest relaxation time and the mean square end-to-end distance, respectively.Comment: 4 pages, 3 figures, submitted to J. Phys. Soc. Jp

Network-constrained models of liberalized electricity markets: the devil is in the details

Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions

Mechanical Behavior Associated with Metallurgical Aspects of Friction Stir Welded Al-Li Alloy Exposed to Exfoliation Corrosion Test

Open Access articleThis research aims to investigate the effect of the exfoliation corrosion exposure time on the mechanical properties, the strength and elongation, of friction stir welded Al-Li alloy type 2195-T8. The exfoliation corrosion test was performed using the exfoliation corrosion (EXCO) solution, based on ASTM G34. The samples were exposed to different exposure times 24, 48, 96, 192 and 384 hours. The results showed that both the strength and elongation of the welded specimens - exposed to the exfoliation corrosion tests - were reduced. For example, the samples that were exposed to 384 hrs, their initial tensile strength and elongation were reduced by 13% and 17% respectively. The degradation process due to the exfoliation corrosion on the tensile strength was divided into three stages: fast (0-96 hrs: 443.7 MPa-416.3 MPa, the degraded rate was 0.29 MPa/h), steady (96-192 hrs: 416.3 MPa-413.4 MPa, the degraded rate was 0.03 MPa/h) and medium rate (192-384 hrs: 413.4 MPa-386.7 MPa, the degraded rate was 0.14 MPa/h). For the elongation, in general, the reduction was similar to the style of strength, but with different rates. The TEM images showed that this degradation was due to the dissolution of T1 (Al2CuLi) and S´ (Al2CuMg) phase. Also, the corrosion products and their role of adherence on the surface of the tested specimens were investigated. An empirical equation p-t (mechanical properties-exposure time) was established to calculate the effect of exposure corrosion time on the performance of welded specimens

Reversibility of Different Types of Capital Flows to Emerging Markets

Most of the emerging market currency crises are accompanied by sharp reversals or “sudden stops” of capital inflows. We investigated whether some types of capital flows are more likely to reverse than others during these crises. Foreign direct investment is usually considered stable while portfolio investment is frequently depicted as the least reliable type of flow. Recent statistical testing has yielded conflicting results on this issue. We argue that a major problem with recent studies is that the degree of variability of capital flows during normal or inflow periods may give little clue to their behavior during crises and it is the latter that is most important for policy. Using data for 35 emerging economies for 1990 through 2003, we confirm that direct investment is the most stable category, but find that private loans on average are as reversible as portfolio flows.Capital flows; currency crises; volatility of capital flows; reversibility of capital flows; Emerging Markets; private loans; portfolio flows; foreign direct investment

Retardation of atherosclerosis in immunocompetent apolipoprotein (apo) E-deficient mice followingliver-directed administration of a [E1-, E3-,polymerase-] adenovirus vector containing the elongation factor-1a promoter driving expression of human apoE cDNA

Although gene transfer of human apolipoprotein E (apoE), a 34-kDa circulating glycoprotein, to the liver of apoEdeficient(apoE-/-) mice using recombinant adenoviral vectors (rAd) is antiatherogenic, its full therapeutic potentialhas yet to be realized. First generation vectors led to immune clearance of transduced hepatocytes, while animproved vector with adenovirus regions E1, E3 and DNA polymerase deleted also had transient effects due tocellular shutdown of the cytomegalovirus (CMV) promoter. Here, we have studied an alternative promoter from thecellular elongation factor 1a (EF-1a) gene, injecting 6-8 week old apoE-/- mice intravenously with 2x1010 virusparticles (vp) of the [E1-, E3-, polymerase-] rAd vector Ad-EF1·-apoE. Plasma apoE levels were low (18-55 ng/ml)and failed to reduce plasma cholesterol or normalize the adverse lipoprotein profile. By contrast, thehyperlipidaemic phenotype of apoE-/- mice treated with Ad-CMV-apoE (2x1010 vp) was transiently normalized.Nevertheless, at termination (265 days) the aortic lesion areas in animals given Ad-EF1·-apoE were significantlyreduced by 15% (P<0.05) compared to untreated animals, a decrease approaching that in Ad-CMV-apoE-treatedmice (23%; P<0.02). Importantly, the attenuation of apoE transgene expression noted with the CMV promoter wasabsent with the EF-1a promoter, which gave relatively sustained, albeit low, levels of plasma apoE throughout thestudy period

Biological surveys of Santa Monica Bay artificial reef and Topanga artificial reef

This report details the development of the biological communities on 2 artificial reefs off southern California (Figure 1). Santa Monica Bay Artificial Reef(SMBAR) and Topanga Artificial Reef(TAR) were both constructed in 1987 with 20,000 and 10,000 tons of quarry rock respectively. SMBAR was constructed in the manner of replication reefs which were designed by researchers to study the effects of environmental and structural variables on reef productivity in situ and TAR was built to promote kelp habitat. SMBAR is composed of 24 module pairs of varying height and rock size arranged along three depth strata while TAR was built in 3 piles along one depth strata (Table 1, Figure 2 & Figure 3). SMBAR is located at 34°00'47''N; 118°32'33" W approximately 5 nautical miles from the Marina del Rey entrance along a course of 290° magnetic. TAR is located at 34°01'38.10" N; 118°31'54.80"W; approximately 5.25 nautical miles from the Marina del Rey entrance along a course of 302° magnetic. The modules of SMBAR cover 3.58 acres of the 256 acres allotted in the permit. Each module has a footprint of about 0.07 acres. The modules of TAR cover 2 acres of 13 acres allotted in the permit. Each module has a footprint of about 0.70 acres. During the late fall of 1995 both reefs were surveyed by Department divers to assess how closely their biological communities had progressed towards a stable "equilibrium" community. Due to the relatively young age of the reefs and the rapid successional change which occurs in the associated biotic communities of new reefs (Carlisle et al. 1964; Turneretal. 1969; Carteretal. 1985; Matthews 1985; Solonsky 1985; Ambrose and Swarbrick 1989; Anderson et al. 1989; Hueckel and Buckley 1989; and WIlson et al. 1990), only qualitative surveys were conducted. (17pp.