Quantitative rainbow schlieren deflectometry

In the rainbow schlieren apparatus, a continuously graded rainbow filter is placed in the back focal plane of the decollimating lens. Refractive-index gradients in the test section thus appear as gradations in huerather than irradiance. Asimple system is described wherein a conventional color CCD array and video digitizer are used to quantify accurately the color attributes of the resulting image, and hence the associated ray deflections. The present system provides a sensitivity comparable with that of conventional interferometry, while being simpler to implement and less sensitive to mechanical misalignment.     

Quantitative species measurements in microgravity flames with near-IR diode lasers

Absolute concentrations of water vapor are measured in microgravity (μ-g), nonpremixed methane, and propane jet flames with diode-laser wavelength modulation spectroscopy. These experiments are performed in the 2.2-s μ-g drop facility at the NASA Lewis Research Center. Abel inversion methods are used to determine time-dependent radial profiles from eight line-of-sight projections across the flames. At all measured heights above the nozzle, water vapor spatial distributions in μ-g flames are much wider than their 1-g counterparts. Radial growth of the water signal continues throughout the drop, verifying earlier suggestions that a steady state is not reached during the duration of the test, despite a quasi-steady flame shape. Large amounts of water vapor are observed at larger radii, at odds with visual (video) observations and numerical predictions.     

Spatio‐temporal variability of suspended sediments in rivers and ecological implications of reservoir flushing operations

High suspended sediment concentrations during reservoir flushing are known to be harmful to biota in downstream river stretches. Therefore, it is common practice to set legal concentration limits for upstream reservoir management operations such as flushings or controlled drawdowns. However, as shown by measurements, there is a considerable spatio‐temporal variability of suspended sediment concentrations both in the longitudinal profile of rivers and in river cross‐sections. To consider this variability in management operations, SED‐FISH—a three‐dimensional modelling approach—was developed to study this variability in a wider context by upscaling cross‐sectional measurements of suspended sediments to high‐resolution three‐dimensional information on the reach scale in an alpine river. The resulting patterns of suspended sediment concentrations were integrated over their respective time of occurrence for various scenarios in order to calculate severity of harmful impacts for target fish species. The modelling results identified refugial habitats with reduced negative impacts in near‐bank zones even for relatively high suspended sediment concentrations in the centre of the river. Moreover, a substantially larger variability of both suspended sediment concentrations and associated harmful impacts was found for a winding riverbed morphology as compared with a straight reach. Both these findings and the developed modelling tool could assist in establishing individual case‐based concentration limits for reservoir management operations in the future and should also be taken into account when planning river regulation or restoration measures.     

Activity qualifiers using an argument-based construction

Supporting and representing the group decision-making process is a complex task that requires very specific aspects. The current existing argumentation models cannot make good use of all the advantages inherent to group decision-making. There is no monitoring of the process or the possibility to provide dynamism to it. These issues can compromise the success of group decision support systems if those systems are not able to provide freedom and all necessary mechanisms to the decision-maker. We investigate the use of argumentation in a completely new perspective that will allow for a mutual understanding between agents and decision-makers. Besides this, our proposal allows to define an agent not only according to the preferences of the decision-maker but also according to his interests towards the decision-making process. We show that our definition respects the requirements that are essential for groups to interact without limitations and that can take advantage of those interactions to create valuable knowledge to support more and better.     

The irradiance volume

A major goal in computer graphics is realistic image synthesis. To this end, illumination methods have evolved from simple local shading models to physically based global illumination algorithms. Local illumination methods consider only the light energy transfer between an emitter and a surface (direct lighting), while global methods account for light energy interactions between all surfaces in an environment, considering both direct and indirect lighting. Even though the realistic effects that global illumination algorithms provide are frequently desirable, the computational expense of these methods is too great for many applications. Dynamic environments and scenes containing a very large number of surfaces often pose problems for global illumination methods. This article presents a different approach to calculating the global illumination of objects. Instead of striving for accuracy at the expense of performance, we rephrase the goal: to achieve a reasonable approximation with high performance. This places global illumination effects within reach of many applications in which visual appearance is more important than absolute numerical accuracy     

Synthesis and characterization of dense and porous cellulose films

Whereas cellulose‐derived polymers are routinely used as membrane materials, the cellulose polymer itself is not directly used to synthesize dense/porous films for membrane applications. Recently, N‐methylmorpholine N‐oxide (NMMO) and dimethylacetamide (DMAc)/lithium chloride (LiCl) have been successfully employed for dissolving unmodified cellulose. This provides a strong rationale for reexamining the possibility of cellulose membrane fabrication using these solvents. By judiciously selecting solvents, casting conditions, and solvent exchange steps, we successfully synthesized dense/asymmetric‐porous cellulose films. The pore size and porosity of the porous films decreased systematically with increasing cellulose concentration. SEM analysis of the cross sections revealed an asymmetric skinned structure with monotonically increasing pore size away from the skin. The measured pore diameters were in the range 1.8–4.8 μm. Mechanical testing indicated that the dense films possessed tensile properties comparable to those of cellulose acetate (CA) films. Though nitrogen permeability values were comparable for cellulose and CA dense films, cellulose film permeability depended upon the type of drying protocol employed. Overall, these results demonstrate that processability need not be a constraint in the use of cellulose polymer for membrane fabrication. In selected applications, cellulose membranes could become a cost‐effective, environmentally friendly alternative to other more commonly employed membrane polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Release of Naturally Derived Antimicrobial Agents from LDPE Films

ABSTRACT: The migration of the naturally derived antimicrobial (AM) agents, linalool, carvacrol, and thymol, from low-density polyethylene (LDPE) films containing ethylene vinyl acetate (EVA) copolymer into the food simulants, isooctane and various ethanol/water mixtures, was studied with a view towards examining the applicability of a first-order kinetic approach as well as a diffusion model approach for describing these systems. The results suggest that the proposed models adequately describe the release of AM agents. The combination of kinetic and diffusion analyses can provide additional information about the release process using the same data set. The analyses suggest that the release of linalool from LDPE/EVA depends on the EVA content in the formulation and that an optimum level of EVA is required to minimize the rate of release. A modification of the existing “idealized diffusion” model is proposed that enables the model to be applied to systems that demonstrate a departure from linearity when subjected to conventional analysis. The applicability of the idealized diffusion model was compared with the “simulant-limited” model and the results suggest that the former model is appropriate for describing most real systems when the simulant (or foodstuff) is favored in the partitioning of the AM agent between the film and the simulant.     

Building a meaning bridge: Therapeutic progress from problem formulation to understanding.

Qualitative analyses of 2 clients' psychotherapies (client centered and process-experiential) investigated the developmental progression from formulating a problem to achieving an understanding of it. The results elaborated one segment in the 8-stage Assimilation of Problematic Experiences Sequence (APES), through which problematic parts of a person (described as voices to emphasize their active, agentic qualities) are thought to pass during successful psychotherapy, as they become assimilated into the self (described as a community of voices). The transition between APES Stage 3 (problem statement/clarification) and APES Stage 4 (understanding/insight) was described as a series of substages. The results highlighted the construction of meaning bridges-semiotic links by which the problematic voice could understand and be understood by voices of the community. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seasonal and diel changes of dissolved oxygen in a hypertrophic prairie lake

Humboldt Lake, a hypertrophic prairie lake typical of many found on the Great Plains of North America, is usually ice‐covered from early November to about mid‐May. The lake is an important recreational fishery, now mainly stocked with walleye. It has a high potential risk of experiencing fish kills because of the very large cyanobacterial blooms that develop in it, the high rates of algal and bacterial production and the high concentrations of ammonia (NH₃‐N) and dissolved organic matter. Following the collapse of cyanobacterial blooms, shallow prairie lakes are known to undergo periods of anoxia that can lead to summer fish kills. In some of the lakes, anoxia forms during the long period of ice cover, causing winter fish kills. Two years of seasonal and diel data (total phosphorus, dissolved oxygen (DO), NH₃‐N and chlorophyll‐a concentrations, and bacterial production) were analysed in this study to assess why significant fish kills did not occur during this period or during the ≈ 30 years of records from Saskatchewan Environment. Humboldt Lake did not become anaerobic, either following the collapse of the cyanobacterial bloom or under ice cover, indicating that the oxygen (O₂) influx (strong mixing) and production processes were greater than the microbial and chemical O₂ demands, both over seasonal and diel time scales. Several published risk threshold criteria to predict the probability of summer and/or winter fish kills were applied in this study. The threshold criteria of maximum summer chlorophyll and maximum winter NH₃‐N concentrations indicated that a summer fish kill was unlikely to occur in this hypertrophic prairie lake, provided its water quality remained similar to that during this study. Similarly, the threshold criteria of initial DO storage before ice cover and the rate of O₂ depletion under ice cover also indicated a winter fish kill was unlikely. However, recent development in the watershed might have resulted in significant water quality deterioration and the winter fish kill that occurred in 2005.     

A dual-process model of defense against conscious and unconscious death-related thoughts: An extension of terror management theory.

Distinct defensive processes are activated by conscious and nonconscious but accessible thoughts of death. Proximal defenses, which entail suppressing death-related thoughts or pushing the problem of death into the distant future by denying one's vulnerability, are rational, threat-focused, and activated when thoughts of death are in current focal attention. Distal terror management defenses, which entail maintaining self-esteem and faith in one's cultural worldview, function to control the potential for anxiety that results from knowing that death is inevitable. These defenses are experiential, are not related to the problem of death in any semantic or logical way, and are increasingly activated as the accessibility of death-related thoughts increases, up to the point at which such thoughts enter consciousness and proximal threat-focused defenses are initiated. Experimental evidence for this analysis is presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)