Network and user interface for PAT DOME virtual motion environment system

The Device for Orientation and Motion Environments Preflight Adaptation Trainer (DOME PAT) provides astronauts a virtual microgravity sensory environment designed to help alleviate tye symptoms of space motion sickness (SMS). The system consists of four microcomputers networked to provide real time control, and an image generator (IG) driving a wide angle video display inside a dome structure. The spherical display demands distortion correction. The system is currently being modified with a new graphical user interface (GUI) and a new Silicon Graphics IG. This paper will concentrate on the new GUI and the networking scheme. The new GUI eliminates proprietary graphics hardware and software, and instead makes use of standard and low cost PC video (CGA) and off the shelf software (Microsoft's Quick C). Mouse selection for user input is supported. The new Silicon Graphics IG requires an Ethernet interface. The microcomputer known as the Real Time Controller (RTC), which has overall control of the system and is written in Ada, was modified to use the free public domain NCSA Telnet software for Ethernet communications with the Silicon Graphics IG. The RTC also maintains the original ARCNET communications through Novell Netware IPX with the rest of the system. The Telnet TCP/IP protocol was first used for real-time communication, but because of buffering problems the Telnet datagram (UDP) protocol needed to be implemented. Since the Telnet modules are written in C, the Adap pragma 'Interface' was used to interface with the network calls

Large droplet impact on water layers

The impact of large droplets onto an otherwise undisturbed layer of water is considered. The work, which is motivated primarily with regard to aircraft icing, is to try and help understand the role of splashing on the formation of ice on a wing, in particular for large droplets where splash appears, to have a significant effect. Analytical and numerical approaches are used to investigate a single droplet impact onto a water layer. The flow for small times after impact is determined analytically, for both direct and oblique impacts. The impact is also examined numerically using the volume of fluid (VOF) method. At small times there are promising comparisons between the numerical results, the analytical solution and experimental work capturing the ejector sheet. At larger times there is qualitative agreement with experiments and related simulations. Various cases are considered, varying the droplet size to layer depth ratio, including surface roughness, droplet distortion and air effects. The amount of fluid splashed by such an impact is examined and is found to increase with droplet size and to be significantly influenced by surface roughness. The makeup of the splash is also considered, tracking the incoming fluid, and the splash is found to consist mostly of fluid originating in the layer

Using virtual environment technology for preadapting astronauts to the novel sensory conditions of microgravity

A unique training device is being developed at the Johnson Space Center Neurosciences Laboratory to help reduce or eliminate Space Motion Sickness (SMS) and spatial orientation disturbances that occur during spaceflight. The Device for Orientation and Motion Environments Preflight Adaptation Trainer (DOME PAT) uses virtual reality technology to simulate some sensory rearrangements experienced by astronauts in microgravity. By exposing a crew member to this novel environment preflight, it is expected that he/she will become partially adapted, and thereby suffer fewer symptoms inflight. The DOME PAT is a 3.7 m spherical dome, within which a 170 by 100 deg field of view computer-generated visual database is projected. The visual database currently in use depicts the interior of a Shuttle spacelab. The trainee uses a six degree-of-freedom, isometric force hand controller to navigate through the virtual environment. Alternatively, the trainee can be 'moved' about within the virtual environment by the instructor, or can look about within the environment by wearing a restraint that controls scene motion in response to head movements. The computer system is comprised of four personal computers that provide the real time control and user interface, and two Silicon Graphics computers that generate the graphical images. The image generator computers use custom algorithms to compensate for spherical image distortion, while maintaining a video update rate of 30 Hz. The DOME PAT is the first such system known to employ virtual reality technology to reduce the untoward effects of the sensory rearrangement associated with exposure to microgravity, and it does so in a very cost-effective manner

A hybrid parametrical wave prediction model

The development of a numerical wave prediction model incorporating a parametrical wind-sea model and a characteristic swell model is described. The parametrical model is an extension of an earlier two-parameter model to the full five Jonswap spectral parameters. An application is presented in which the model is used to hindcast severe wave conditions in the North Sea as part of an engineering study to define long-term extreme wave statistics for the area. The limitations of the model and the needs for future research are discussed

Association of the CCR5 gene with juvenile idiopathic arthritis

The CC chemokine receptor 5 (CCR5) has been shown to be important in the recruitment of T-helper cells to the synovium, where they accumulate, drive the inflammatory process and the consequent synovitis and joint destruction. A 32 base-pair insertion/deletion variant (CCR5Δ32) within the gene leads to a frame shift and a nonfunctional receptor. CCR5Δ32 has been investigated for its association with juvenile idiopathic arthritis (JIA), with conflicting results. The aim of this study was to investigate whether CCR5Δ32 is associated with JIA in an UK population. CCR5Δ32 was genotyped in JIA cases (n=1054) and healthy controls (n=3129) and genotype and allele frequencies were compared. A meta-analysis of our study combined with previously published studies was performed. CCR5Δ32 was significantly associated with protection from developing JIA, in this UK data set (P(trend)=0.006, odds ratio (OR) 0.79 95% confidence interval (95% CI): 0.66-0.94). The meta-analysis of all published case-control association studies confirmed the protective association with JIA (P=0.001 OR 0.82 95% CI: 0.73-0.93). CCR5Δ32 is a functional variant determining the number of receptors on the surface of T cells, and it is hypothesized that the level of CCR5 expression could influence the migration of proinflammatory T cells into the synovium and thus susceptibility to JIA

Drop Splashing on a Dry Smooth Surface

The corona splash due to the impact of a liquid drop on a smooth dry substrate is investigated with high speed photography. A striking phenomenon is observed: splashing can be completely suppressed by decreasing the pressure of the surrounding gas. The threshold pressure where a splash first occurs is measured as a function of the impact velocity and found to scale with the molecular weight of the gas and the viscosity of the liquid. Both experimental scaling relations support a model in which compressible effects in the gas are responsible for splashing in liquid solid impacts.Comment: 11 pages, 4 figure

Association of the AFF3 gene and IL2/IL21 gene region with juvenile idiopathic arthritis

Recent genetic studies have led to identification of numerous loci that are associated with susceptibility to autoimmune diseases. The strategy of using information from these studies has facilitated the identification of novel juvenile idiopathic arthritis (JIA) susceptibility loci, specifically, PTPN22 and IL2RA. Several novel autoimmune susceptibility loci have recently been identified, and we hypothesise that single-nucleotide polymorphisms (SNPs) within these genes may also be JIA susceptibility loci. Five SNPs within the genes AFF3, IL2/IL21, IL7R, CTLA4 and CD226, previously associated with multiple autoimmune diseases were genotyped, in a large data set of Caucasian JIA patients and controls, and tested for association with JIA. We identified two susceptibility loci for JIA, AFF3 and the IL2/IL21 region and additional weak evidence supporting an association with the CTLA4 and IL7R genes, which warrant further investigation. All results require validation in independent JIA data sets. Further characterisation of the specific causal variants will be required before functional studies can be performed