2,653 research outputs found

    Object Location Memory Error in Virtual and Real Environments

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    We aim to further explore the transfer of spatial knowledge from virtual to real spaces. Based on previous research on spatial memory in immersive virtual reality (VR) we ran a study that looked at the effect of three locomotion techniques (joystick, pointing-and-teleporting and walking-in-place) on object location learning and recall. Participants were asked to learn the location of a virtual object in a virtual environment (VE). After a short period of time they were asked to recall the location by placing a real version of the object in the real-world equivalent environment. Results indicate that the average placement error, or distance between original and recalled object location, is approximately 20cm for all locomotion technique conditions. This result is similar to the outcome of a previous study on spatial memory in VEs that used real walking. We report this unexpected finding and suggest further work on spatial memory in VR by recommending the replication of this study in different environments and using objects with a wider diversity of properties, including varying sizes and shapes

    The Effect of Environmental Features, Self-Avatar, and Immersion on Object Location Memory in Virtual Environments

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    One potential application for virtual environments (VEs) is the training of spatial knowledge. A critical question is what features the VE should have in order to facilitate this training. Previous research has shown that people rely on environmental features, such as sockets and wall decorations, when learning object locations. The aim of this study is to explore the effect of varied environmental feature fidelity of VEs, the use of self-avatars, and the level of immersion on object location learning and recall. Following a between-subjects experimental design, participants were asked to learn the location of three identical objects by navigating one of the three environments: a physical laboratory or low and high detail VE replicas of this laboratory. Participants who experienced the VEs could use either a head-mounted display (HMD) or a desktop computer. Half of the participants learning in the HMD and desktop systems were assigned a virtual body. Participants were then asked to place physical versions of the three objects in the physical laboratory in the same configuration. We tracked participant movement, measured object placement, and administered a questionnaire related to aspects of the experience. HMD learning resulted in statistically significant higher performance than desktop learning. Results indicate that, when learning in low detail VEs, there is no difference in performance between participants using HMD and desktop systems. Overall, providing the participant with a virtual body had a negative impact on performance. Preliminary inspection of navigation data indicates that spatial learning strategies are different in systems with varying levels of immersion

    Development of organic fertilizers from food market waste and urban gardening by composting in Ecuador

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    Currently, the management of urban waste streams in developing countries is not optimized yet, and in many cases these wastes are disposed untreated in open dumps. This fact causes serious environmental and health problems due to the presence of contaminants and pathogens. Frequently, the use of specific low-cost strategies reduces the total amount of wastes. These strategies are mainly associated to the identification, separate collection and composting of specific organic waste streams, such as vegetable and fruit refuses from food markets and urban gardening activities. Concretely, in the Chimborazo Region (Ecuador), more than 80% of municipal solid waste is dumped into environment due to the lack of an efficient waste management strategy. Therefore, the aim of this study was to develop a demonstration project at field scale in this region to evaluate the feasibility of implanting the composting technology not only for the management of the organic waste fluxes from food market and gardening activities to be scaled-up in other developing regions, but also to obtain an end-product with a commercial value as organic fertilizer. Three co-composting mixtures were prepared using market wastes mixed with pruning of trees and ornamental palms as bulking agents. Two piles were created using different proportions of market waste and prunings of trees and ornamental palms: pile 1 (50:33:17) with a C/N ratio 25; pile 2: (60:30:10) with C/N ratio 24 and pile 3 (75:0:25) with C/N ratio 33), prepared with market waste and prunings of ornamental palm. Throughout the process, the temperature of the mixtures was monitored and organic matter evolution was determined using thermogravimetric and chemical techniques. Additionally, physico-chemical, chemical and agronomic parameters were determined to evaluate compost quality. The results obtained indicated that all the piles showed a suitable development of the composting process, with a significant organic matter decomposition, reached in a shorter period of time in pile 3. At the end of the process, all the composts showed absence of phytotoxicity and suitable agronomic properties for their use as organic fertilizers. This reflects the viability of the proposed alternative to be scaled-up in developing areas, not only to manage and recycle urban waste fluxes, but also to obtain organic fertilizers, including added value in economic terms related to nutrient contents.Peer ReviewedPostprint (published version

    Caracterizaci贸n de la membrana NF-97 mediante disoluciones salinas. Aplicaci贸ndel modelo de Spiegler-Kedem-Kachalsky

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    Los procesos f脥sicos basados en las tecnolog脥as de membrana se muestran como una clara alternativa en el campo de la desalinizaci贸n y tratamiento de aguas. Un paso previo en el dise帽o de estos procesos consiste en la selecci贸n y caracterizaci贸n de las membranas que van a ser utilizadas, siendo estos ensayos de gran utilidad para predecir el comportamiento de las mismas durante su posterior empleo. En este trabajo se ha caracterizado, mediante el uso de dos disoluciones salinas distintas, la membrana de nanofiltraci贸n de poliamida (NF-97), al objeto de obtener sus condiciones 贸ptimas de funcionamiento. Los resultados obtenidos se han ajustado al modelo de transporte de flujo a trav茅s de la membrana de Spiegler-Kedem-Katchalsky, determinando, mediante resoluci贸n gr谩fica, las constantes del mismo. Se ha comprobado que el modelo es adecuado para describir el proceso de eliminaci贸n de las sales mediante nanofiltraci贸n, lo que permite predecir el comportamiento de la membrana en otras condiciones de operaci贸n

    Development of a novel equine influenza virus live-attenuated vaccine

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    H3N8 equine influenza virus (EIV) is an important and significant respiratory pathogen of horses. EIV is enzootic in Europe and North America, mainly due to the suboptimal efficacy of current vaccines. We describe, for the first time, the generation of a temperature sensitive (ts) H3N8 EIV live-attenuated influenza vaccine (LAIV) using reverse-genetics approaches. Our EIV LAIV was attenuated (att) in vivo and able to induce, upon a single intranasal administration, protection against H3N8 EIV wild-type (WT) challenge in both a mouse model and the natural host, the horse. Notably, since our EIV LAIV was generated using reverse genetics, the vaccine can be easily updated against drifting or emerging strains of EIV using the safety backbone of our EIV LAIV as master donor virus (MDV). These results demonstrate the feasibility of implementing a novel EIV LAIV approach for the prevention and control of currently circulating H3N8 EIVs in horse populations

    Crystal structure of the catalytic fragment of murine poly(ADP-ribose) polymerase-2.

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    Poly(ADP-ribose) polymerase-1 (PARP-1) has become an important pharmacological target in the treatment of cancer due to its cellular role as a 'DNA-strand break sensor', which leads in part to resistance to some existing chemo- and radiological treatments. Inhibitors have now been developed which prevent PARP-1 from synthesizing poly(ADP-ribose) in response to DNA-breaks and potentiate the cytotoxicity of DNA damaging agents. However, with the recent discoveries of PARP-2, which has a similar DNA-damage dependent catalytic activity, and additional members containing the 'PARP catalytic' signature, the isoform selectivity and resultant pharmacological effects of existing inhibitors are brought into question. We present here the crystal structure of the catalytic fragment of murine PARP-2, at 2.8 A resolution, and compare this to the catalytic fragment of PARP-1, with an emphasis on providing a possible framework for rational drug design in order to develop future isoform-specific inhibitors

    CLIENTS' PREFERENCE FOR LOW-COST RESIDENTIAL PROPERTIES: A CONJOINT ANALYSIS

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    The purpose of this study was to determine the clients鈥 preference for residential property in Digos City in the southern part of the Philippines. Through the examination of the five attributes (location, equity, terms of payment, floor area, and the price) and their corresponding levels using conjoint analysis, the order of relative importance of each attribute was determined together with the utility estimates to determine the client鈥檚 preference for a low-cost residential property. Twenty plancards containing hypothetical combinations were generated via an orthogonal array and were administered to 400 medium-income individuals. Results revealed that price is the most important attribute, followed by location, terms of payment, and floor area, while equity was found the least important attribute. It can also be inferred that the overall sample preferred low-cost housing near the school, outright or staggered payment for the equity, payable in 20 years with a floor area of 45 sqm (single-detached) in a 100 sqm lot and with a price of Php 500,000. The most preferred low-cost residential property is a combination of the following attribute levels: near the school of children, staggered payment for equity, with terms of payment payable in 10 years, with a floor area of 45 sqm (single-detached) in a 100 sqm lot and can be bought for Php 500,000.聽JEL: R30; R31聽 Article visualizations

    I See, I Think I Wonder: An Evaluation of Journaling as a Critical Reflective Practice Tool for Aiding Teachers in Challenging or Confronting Contexts

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    In October 2011, five selected Western Australian teachers took part in a teacher mentoring project in Tanzania. The teachers spent a month embedded in local primary and secondary schools, working collaboratively with their Tanzanian counterparts. As a strategy for making sense of their experiences, each teacher was asked to maintain a reflective journal, using the Harvard Visible Thinking Routine of 鈥榮ee, think, wonder鈥 as a critical structure for guiding their journal writing. The purpose of this article is to discuss the effectiveness of journaling for teachers in challenging teaching situations, and the usefulness of the Harvard approach in structuring the reflective process as part of an action-based reflective model. As such, the article examines not just the role of critical journaling in helping the participating teachers make sense of their African experience, but the potential of this approach in general in helping teachers faced with challenging or confronting teaching contexts
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