Towards the 3D Web with Open Simulator

Continuing advances and reduced costs in computational power, graphics processors and network bandwidth have led to 3D immersive multi-user virtual worlds becoming increasingly accessible while offering an improved and engaging Quality of Experience. At the same time the functionality of the World Wide Web continues to expand alongside the computing infrastructure it runs on and pages can now routinely accommodate many forms of interactive multimedia components as standard features - streaming video for example. Inevitably there is an emerging expectation that the Web will expand further to incorporate immersive 3D environments. This is exciting because humans are well adapted to operating in 3D environments and it is challenging because existing software and skill sets are focused around competencies in 2D Web applications. Open Simulator (OpenSim) is a freely available open source tool-kit that empowers users to create and deploy their own 3D environments in the same way that anyone can create and deploy a Web site. Its characteristics can be seen as a set of references as to how the 3D Web could be instantiated. This paper describes experiments carried out with OpenSim to better understand network and system issues, and presents experience in using OpenSim to develop and deliver applications for education and cultural heritage. Evaluation is based upon observations of these applications in use and measurements of systems both in the lab and in the wild.Postprin

Growing the use of Virtual Worlds in education : an OpenSim perspective

The growth in the range of disciplines that Virtual Worlds support for educational purposes is evidenced by recent applications in the fields of cultural heritage, humanitarian aid, space exploration, virtual laboratories in the physical sciences, archaeology, computer science and coastal geography. This growth is due in part to the flexibility of OpenSim, the open source virtual world platform which by adopting Second Life protocols and norms has created a de facto standard for open virtual worlds that is supported by a growing number of third party open source viewers. Yet while this diversity of use-cases is impressive and Virtual Worlds for open learning are highly popular with lecturers and learners alike immersive education remains an essentially niche activity. This paper identifies functional challenges in terms of Management, Network Infrastructure, the Immersive 3D Web and Programmability that must be addressed to enable the wider adoption of Open Virtual Worlds as a routine learning technology platform. We refer to specific use-cases based on OpenSim and abstract generic requirements which should be met to enable the growth in use of Open Virtual Worlds as a mainstream educational facility. A case study of a deployment to support a formal education curriculum and associated informal learning is used to illustrate key points.Postprin

Exploiting light-based 3D-printing for the fabrication of mechanically enhanced, patient-specific aortic grafts

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ±0.05 MPa and 1.61 ±0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts

The Impossibility of a Perfectly Competitive Labor Market

Using the institutional theory of transaction cost, I demonstrate that the assumptions of the competitive labor market model are internally contradictory and lead to the conclusion that on purely theoretical grounds a perfectly competitive labor market is a logical impossibility. By extension, the familiar diagram of wage determination by supply and demand is also a logical impossibility and the neoclassical labor demand curve is not a well-defined construct. The reason is that the perfectly competitive market model presumes zero transaction cost and with zero transaction cost all labor is hired as independent contractors, implying multi-person firms, the employment relationship, and labor market disappear. With positive transaction cost, on the other hand, employment contracts are incomplete and the labor supply curve to the firm is upward sloping, again causing the labor demand curve to be ill-defined. As a result, theory suggests that wage rates are always and everywhere an amalgam of an administered and bargained price. Working Paper 06-0

Effect of historical changes in land use and climate on the water budget of an urbanizing watershed

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Water Resources Research 42 (2006): W03426, doi:10.1029/2005WR004131.We assessed the effects of historical (1931-1998) changes in both land-use and climate on the water budget of a rapidly urbanizing watershed, Ipswich River basin (IRB), in northeastern Massachusetts. Water diversions and extremely low flow during summer are major issues in the IRB. Our study centers on a detailed analysis of diversions and a combined empirical/modeling treatment of evapotranspiration (ET) response to changes in climate and land-use. A detailed accounting of diversions showed that net diversions increased due to increases in water withdrawals (primarily ground water pumping) and export of sewage. Net diversions constitute a major component of runoff (20% of streamflow). Using a combination of empirical analysis and physically based modeling we related an increase in precipitation (2.7 mm/yr) and changes in other climate variables to an increase in ET (1.7 mm/yr). Simulations with a physically based water-balance model showed that the increase in ET could be attributed entirely to a change in climate, while the effect of land-use change was negligible. The land-use change effect was different from ET and runoff trends commonly associated with urbanization. We generalized these and other findings to predict future streamflow using climate change scenarios. Our study could serve as a framework for studying suburban watersheds, being the first study of a suburban watershed that addresses long-term effects of changes in both land-use and climate, and accounts for diversions and other unique aspects of suburban hydrology.This research was partially supported by NSF grants (DEB-9726862, OCE-9726921 and OCE-0423565)

Previously unpublished Odonata records from Sarawak, Borneo, part VI: Miri Division including checklists for Niah, Lambir Hills, Loagan Bunut and Pulong Tau National Parks.

Recods of Odonata made from 2005 to 2020 in Miri Division in Sarawak are presented, including records from Lambir Hills, Loagan Bunut, Niah and Pulong Tau National Parks. Primary types of Odonata originating from Miri Division are listed. Surveys of more than one day duration in Miri Division and covered here are tabulated with the funding source where appropriate; four of the surveys covered here were funded by the International Dragonfly Fund. One hundred and eighty-eight species are listed based on surveys made by the authors, of which Macromia jucunda Lieftinck, 1955, had not been recorded from Borneo before, Burmagomphus arthuri Lieftinck, 1953 is a new record for Miri Division and Camacinia gigantea (Brauer, 1867) has only been recorded from the Division re-cently with the only published record in a difficult to access publication (Choong (2020)). At least 48 more of the species listed were recorded from Miri Division for the first time in surveys covered in this report, although the records have been published (in most cases with no details beyond division and district in Dow (2021)) before. Two forms of Xiphi-agrion cyanomelas Selys, 1876 are recorded and the likelihood that they represent different species is discussed. A possibly new, large sized, species of Macromia allied to M. westwoodii Selys, 1874 is recorded and discussed. Other notable records not published with details before include Rhinocypha stygia Förster, 1897, Rhinoneura caerulea Kimmins, 1936, Dysphaea lugens (Selys, 1873), Euphaea ameeka van Tol & Norma-Rashid, 1995, Euphaea basalis (Laidlaw, 1915), Amphicnemis new sp. cf mariae Lieftinck, 1940 (previously recorded from Usun Apau National Park), Anaciaeschna jaspidea (Burmeister, 1839), Heliaeschna uninervulata Martin, 1909, Borneogomphus sp., Heliogomphus borneensis Lieftinck, 1964, Ictinogomphus acutus (Laidlaw, 1914), Chlorogomphus sp., Macromia corycia Laidlaw, 1922, Idionyx montana Karsch, 1891, Hylaeothemis clementia Ris, 1909, Orchithemis xanthosoma Laidlaw, 1911, Rhyothemis fulgens Kirby, 1889, Rhyothemis regia (Brauer, 1867), Tetrathemis sp. cf platyptera Selys, 1878, Tramea phaeoneura Lieftinck, 1953 and Tramea sp. cf virginia (Rambur, 1842). The habitat preferences of Dysphaea lugens are discussed. A male-male tandem of Coeliccia nigrohamata Laidlaw, 1918 is reported. The somewhat peculiar distribution of Argiocnemis rubescens rubeola Selys, 1877 and Pseudothemis jorina Förster, 1904 in Sarawak is discussed. Activity of the apparently normally crepuscular Heliaeschna uninervulata in the middle of the day is reported. An interesting morphological detail of some female Chlorogomphus from Sarawak is discussed. The likelihood that Macromia corycia is a junior synonym of M. gerstaeckeri Krüger, 1899 is discussed. The possibility that the range of Rhyothemis regia is expanding in Sarawak is remarked upon. The identity of Tramea sp. cf virginia is discussed. With the records presented here at least 222 species of Odonata are known from Miri Division and with the addition of Macromia jucunda to the known fauna, 309 species have now been recorded from Sarawak. More detailed specimen records are given in Appendix 1 and a revised checklist of Odonata from Lambir Hills National Park and the first checklis from Loagan Bunut, Niah and Pulong Tau National Parks are given in Appendix 2

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy