An overview of decision networks and organizations

The paper summarizes recent results on both binary and M-ary distributed hypothesis testing problems with decision makers (DMs) organized in structured decision networks. The general problem of finding an optimal organizational structure and decision strategy for such networks is formulated as a functional optimization problem. A normative model to study the effect of interactions between task structure and organizational design on the performance of hierarchical organizations is presented. A binary signal detection model is considered to illustrate the joint impact of organizational design and of task environment on the organizational decision performance. The concept of a congruent organizational structure (i.e., a structure that achieves centralized performance with minimal communication) is introduced, and a graph decomposition algorithm to synthesize congruent structures is discussed     

Measuring and modelling the reflectance spectra of male Swinhoe's pheasant feather barbules

A range of iridescent colour appearances are presented by male Swinhoe''s pheasants'' (Lophura swinhoii) mantle feathers. Two distinct regions of the open pennaceous portion of its feathers display particularly conspicuous angle-dependent reflection. A bright blue band appears in one region at normal incidence that spatially shifts to another at higher illumination angles. The two-dimensional photonic crystal-like nanostructures inside the barbules of these two regions are similar. However, this study found that the spatial variation in their colour appearance results from a continuously changing orientation of barbules with respect to the alignment of their associated barb. A multi-layered rigorous coupled-wave analysis approach was used to model the reflections from the identified intra-barbule structures. Well-matched simulated and measured reflectance spectra, at both normal and oblique incidence, support our elucidation of the origin of the bird''s distinctive feather colour appearance.     

Determining moisture levels in straw bale construction

The use of straw bales for the construction of buildings in the UK has to date generally been limited to the self-build fringe sector. In order to bring this form of construction into the mainstream sector, to benefit from its inherent low carbon and high insulation characteristics, it is necessary to guarantee the long-term durability of the straw. Maintaining low moisture levels is critical to the long-term resistance of straw to biological decomposition. This paper presents results from a study on moisture monitoring in straw bale construction, and includes the development of an empirical equation which relates straw moisture content to surrounding microclimate relative humidity and temperature. This knowledge allows continuous non-invasive condition monitoring of the straw in on-going research work and potentially as part of future managed maintenance of straw bale buildings.     

The alpha prime to delta reversion transformation in Pu-Ga alloys

The α′→δ reversion transformation in stabilized δ phase Pu-Ga alloys containing 0.5 wt.% and 0.6 wt.% Ga was studied using dilatometry and differential scanning calorimetry. The α′→δ reversion was observed to occur as a series of transformation bursts spread over a 20°C to 40°C temperature range. The enthalpy of the endothermic α′→δ reversion transformation was estimated to be approximately 0.56 J/g for the 0.6 wt.% Ga alloy. Lower gallium was found to raise the α′→δ reversion temperature in specimens cooled to −155°C from 44–48°C for 0.6 wt.% Ga to 92°C for 0.5 wt.% Ga. Repeated cycling to −155°C caused the reversion onset temperature to decrease by ∼10°C. Raising the minimum hold temperature from −150°C to −125°C caused the reversion onset temperature to decrease by 5–10°C. Annealing at 300–400°C was required to erase all traces of the effects of cold exposure; material heated to only 200°C after thermal cycling displayed decreased reversion onset temperatures during subsequent thermal cycling. For more information, contact D.S. Schwartz, Los Alamos National Laboratory, NMT Division, Los Alamos, New Mexico 87545.     

Design of humanitarian tents for use in cold climates

Extreme climatic risks pose significant challenges to displaced populations that often lack adequate shelter. Contemporary policy documents concerning emergency shelter reveal that the scope of shelter-associated risk is much wider than simply exposure to the elements and includes a significant social dimension. However, disparity exists between implicitly accepted risks described in aid agency literature and field practice. Experience in recent disaster assistance programmes in Kosovo and Afghanistan illustrates how ill equipped the aid community is to deal with cold weather affecting transitional settlements. A review of the environmental risks associated with living in tented accommodation in cold climates reveals the difficulty of providing thermal comfort and fire safety in both heated and unheated tents. In addition, social surveys and field trials with displaced populations in Afghanistan illustrate that shelter is used, perceived and valued differently according to the ethnic and cultural background of occupants, and that these are also factors that impact on the risks they bear. Several design recommendations and guides for the use of cold climate relief tents are made, whilst acknowledging that the provision of alternative, longer-term shelter provision during the phase of emergency response is nearly always preferable.     

Refractory metals: A primer

Refractory metals have found wide-spread use in structural, electronic, chemical, and nuclear applications because they display unique physical and mechanical properties over a wide range of temperatures. Modern purification, processing, and alloying techniques have made a wide variety of refractory metals available in standard mill product form. Smaller quantities of non-typical alloys can also be made. As a whole, nearly one million tonnes of refractory metals are produced each year worldwide.     

Symptom-dependent taste aversion induced by an anticoagulant rodenticide in the brown rat (–Rattus norvegicus–R).

In a series of 3 experiments with different experimental paradigms, feeding patterns of laboratory rats (Rattus norvegicus) were monitored in 2-choice feeding tests after intubation with a sublethal dose of an anticoagulant rodenticide. The authors report for the first time that contrary to accepted wisdom, anticoagulants can induce taste aversions. Furthermore, we report behavioral symptoms within the 1st day after dosing. Our data suggest that the taste aversion is induced through an inhibition of the vitamin K cycle and is transient, attenuating over the same period as the levels of vitamin K-dependent proteins return to normal. Because the taste aversion is expressed most strongly when symptoms are most pronounced and is not expressed after symptoms have disappeared, the authors term this novel form of control symptom-dependent taste aversion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stable, dispersible surface-enhanced Raman scattering substrate capable of detecting molecules bound to silica-immobilized ligands

A stable surface-enhanced Raman scattering (SERS) substrate is developed through immobilization of gold sols onto aminated silica beads. The plasmon resonance is established by spacing of gold sols on the bead surface and remains stable over extended periods of time due to the large number of amine groups that provide stable anchoring of gold to the surface. Unlike planar supports, this substrate can be dispersed in a sample, providing high surface area for detection and efficient transport of analytes to its surface. This substrate can be used to detect the binding of a molecule to ligands on the silica surface, which avoids the stability limitations of thiol-bound ligands on gold. Chemical modification of the amine groups on the silica surface with benzoic anhydride could be readily detected in Raman scattering enhanced by the neighboring gold sols, with nearly the same sensitivity as benzylthiol bound directly to the gold surfaces. This result suggests future work involving the immobilization of other ligands through the residual amine groups to the silica, which could be used to selectively attract target analytes to the SERS-active surface.