Using virtual worlds as collaborative environments for innovation and design: lessons learned and observations from case studies in architectural projects

In this paper we discuss observations and lessons learned in conducting architectural design projects in virtual worlds. By integrating a community of users in virtual worlds into a collaborative architectural design process, organisations can tap the community's creativity and intelligence through immersive technology. The paper provides an overview of the latest advances of information and communication technologies in immersive virtual environments and discusses some of the observations and lessons learned which should be taken into account in developing collaboration models for such activities. Here we propose four modes of collaboration, based on the choices for degree of openness and governance structure, which are illustrated by four case studies

Viking GC/MS mechanisms design and performance

The Viking Lander gas chromatograph/mass spectrometer will analyze pyrolyzed samples of the Martian surface for organic content. The surface-sample loader and pyrolyzer assembly (SSPLA) is described, along with the major problems encountered during design and testing. Three mechanisms were developed to implement the required SSLPA functions: (1) a soil loader that forces soil from a filled rotating funnel into each of three ovens located on a carriage, (2) a Geneva drive for rotating and precisely indexing the ovens to receive sample, and (3) a toggle-clamp mechanism for sealing the ovens by forcing circular double knife edges into gold sealing surfaces

Exact methods for Campi plots

We introduce for canonical fragmention models an exact method for computing expectation values which exclude the largest cluster. This method allows for the computation of the reduced multiplicity and other quantities of interest introduced by Campi, and a comparison shows that the percolation model and a recent canonical model differ mostly only in small respects in these ensemble averages.Comment: 7 pages, revtex 3.0, 2 figs. available on reques

Debris control design achievements of the booster separation motors

The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented

Effects of pharmaceutical wastes on growth of microalgae

The purpose of this work was to assay samples of waste material from Puerto Rican pharmaceutical industries for inhibition of growth of algae. Two samples (noted as I and II) supplied to us were tested for toxicity to six microalgae. The test organisms, two blue-green algae, two green algae, and two diatoms [r]epresent three major divisions of algae.University of Texas Marine Science InstituteMarine Scienc

Criticality and isostaticity in fiber networks

The rigidity of elastic networks depends sensitively on their internal connectivity and the nature of the interactions between constituents. Particles interacting via central forces undergo a zero-temperature rigidity-percolation transition near the isostatic threshold, where the constraints and internal degrees of freedom are equal in number. Fibrous networks, such as those that form the cellular cytoskeleton, become rigid at a lower threshold due to additional bending constraints. However, the degree to which bending governs network mechanics remains a subject of considerable debate. We study disordered fibrous networks with variable coordination number, both above and below the central-force isostatic point. This point controls a broad crossover from stretching- to bending-dominated elasticity. Strikingly, this crossover exhibits an anomalous power-law dependence of the shear modulus on both stretching and bending rigidities. At the central-force isostatic point---well above the rigidity threshold---we find divergent strain fluctuations together with a divergent correlation length $\xi$, implying a breakdown of continuum elasticity in this simple mechanical system on length scales less than $\xi$.Comment: 6 pages, 5 figure

Biodegradation of aromatic compounds by high latitude phytoplankton

"It was the purpose of the work undertaken to bring into pure culture representative diatoms from the Cook Inlet and the ice-edge in the Bering Sea and to examine their capacity for the oxidation of aromatic compounds using naphthalene as a model substrate. Three diatoms from the Cook Inlet (Kasitsna Bay) were shown to metabolize naphthalene at 6 or 12°C to 1-naphthol and other unidentified ethyl acetate and water-soluble products. Likewise, three diatoms isolated from samples collected at the ice-edge in the Bering Sea also formed small amounts of 1-naphthol from naphthalene when incubated in the light at 0 or 10°C. We have not been able to rigorously prove that any algal cell, be it a blue-green alga, a green alga, or a diatom can metabolize (1-¹⁴C) naphthalene far enough to produce ¹⁴CO₂. However, if we assume a stoichiometery of one 1-naphthol in the algae equivalent to one CO₂ in bacteria, then for mesophilic algae, the rate of 1-naphthol production is roughly estimated as 10% of the in situ marine potential, and perhaps higher if only the photic zone is considered. We have as yet, no corresponding values for rate of 1-naphthol formation from naphthalene by cold-adapted or psychrophilic diatom cultures, however, it seems reasonable to suggest that algal aromatic transformations may also be a significant fraction of bacterial activity in cold environments. In addition to studies on the oxidation of naphthalene we have also examined the sensitivity of the Bering Sea psychrophilic diatoms to crude oil samples from Cook Inlet and Prudhoe Bay. The results with pure cultures indicate that the toxicity of crude oil was enhanced in psychrophilic diatoms growing at O°C or 10°C as compared to previous studies with mesophilic forms. There are several important consequences of the results for Alaskan OCS oil and gas development. It is now clear that pure cultures of diatoms isolated from either the lower Cook Inlet or from the ice-edge in the Bering Sea can oxidize aromatic compounds such as naphthalene. Whether the metabolites persist through the food chain and will be more or less toxic than naphthalene itself is not known. The results with naphthalene also imply that the photic zone can be an important sink for aromatic hydrocarbon transformations. There are certainly differences among microalgae in the capacity to oxidize naphthalene. It seems prudent, therefore, to insure, via monitoring, that accidental introduction of aromatic compounds in Alaskan waters does not cause a selective or enrichment effect on existing phytoplankton populations. A second area of environmental concern is the suggestion of an enhanced crude oil toxicity in slower growing psychrophilic diatoms as compared to their mesophilic cousins. Crude oil spills near or under the sea ice may severely impact primary productivity, and thereby higher tropic level.Final report RD/MPF24-Effects-675April 30, 1982Marine Scienc

Differences in diet of Atlantic bluefin tuna (Thunnus thynnus) at five seasonal feeding grounds on the New England continental shelf

The stomachs of 819 Atlantic bluefin tuna (Thunnus thynnus) sampled from 1988 to 1992 were analyzed to compare dietary differences among five feeding grounds on the New England continental shelf (Jeffreys Ledge, Stellwagen Bank, Cape Cod Bay, Great South Channel, and South of Martha’s Vineyard) where a majority of the U.S. Atlantic commercial catch occurs. Spatial variation in prey was expected to be a primary influence on bluefin tuna distribution during seasonal feeding migrations. Sand lance (Ammodytes spp.), Atlantic herring (Clupea harengus), Atlantic mackerel (Scomber scombrus), squid (Cephalopoda), and bluefish (Pomatomus saltatrix) were the top prey in terms of frequency of occurrence and percent prey weight for all areas combined. Prey composition was uncorrelated between study areas, with the exception of a significant association between Stellwagen Bank and Great South Channel, where sand lance and Atlantic herring occurred most frequently. Mean stomach-contents biomass varied significantly for all study areas, except for Great South Channel and Cape Cod Bay. Jeffreys Ledge had the highest mean stomach-contents biomass (2.0 kg) among the four Gulf of Maine areas and Cape Cod Bay had the lowest (0.4 kg). Diet at four of the five areas was dominated by one or two small pelagic prey and several other pelagic prey made minor contributions. In contrast, half of the prey species found in the Cape Cod Bay diet were demersal species, including the frequent occurrence of the sessile fig sponge (Suberites ficus). Prey size selection was consistent over a wide range of bluefin length. Age 2–4 sand lance and Atlantic herring and age 0–1 squid and Atlantic mackerel were common prey for all sizes of bluefin tuna. This is the first study to compare diet composition of western Atlantic bluefin tuna among discrete feeding grounds during their seasonal migration to the New England continental shelf and to evaluate predator-prey size relationships. Previous studies have not found a common occurrence of demersal species or a pre-dominance of Atlantic herring in the diet of bluefin tuna