Distributed OpenGL Rendering in Network Bandwidth Constrained Environments

Display walls made from multiple monitors are often used when very high resolution images are required. To utilise a display wall, rendering information must be sent to each computer that the monitors are connect to. The network is often the performance bottleneck for demanding applications, like high performance 3D animations. This paper introduces ClusterGL; a distribution library for OpenGL applications. ClusterGL reduces network traffic by using compression, frame differencing and multi-cast. Existing applications can use ClusterGL without recompilation. Benchmarks show that, for most applications, ClusterGL outperforms other systems that support unmodified OpenGL applications including Chromium and BroadcastGL. The difference is larger for more complex scene geometries and when there are more display machines. For example, when rendering OpenArena, ClusterGL outperforms Chromium by over 300% on the Symphony display wall at The University of Waikato, New Zealand. This display has 20 monitors supported by five computers connected by gigabit Ethernet, with a full resolution of over 35 megapixels. ClusterGL is freely available via Google Code

Heat-flow monotonicity of Strichartz norms

Most notably we prove that for $d=1,2$ the classical Strichartz norm $$\|e^{i s\Delta}f\|_{L^{2+4/d}_{s,x}(\mathbb{R}\times\mathbb{R}^d)}$$ associated to the free Schr\"{o}dinger equation is nondecreasing as the initial datum $f$ evolves under a certain quadratic heat-flow.Comment: 11 page

What Works? A Study of Effective Early Childhood Mental Health Consultation Programs

Examines factors that lead to desirable outcomes in mental health consultation programs: solid program infrastructure, highly qualified consultants, and quality support services. Analyzes targeted outcomes, measurements, and intensity of interventions

An empirical phenomenological investigation of procrastinating behaviour

A qualitative empirical phenomenological study was undertaken to determine the self-experience of procrastinating behaviour. Five students each gave an account of an occasion when they procrastinated. The resultant protocols were analysed and the Situated Structure of each individual’s experience was reported. From these, the General Structure of procrastinating behaviour was determined. A further, novel step was added to the standard methodology, whereby ‘themes’ were extracted from participant protocols and a ‘Composite Reality’ of everyday-life procrastination was rendered. Participants’ accounts suggest they are concerned the results of intellectual tasks they undertake will be seen as equivalent to their quality of being-as-an-individual: poor work results will be interpreted by important-others as evidence of participants’ poor quality of self – which is to be avoided. This study suggests that procrastination is a ploy used by individuals to avoid criticism, by deflecting assessment of their capacity to complete a task well, to instead, what they are capable of when only a limited time is available. Conclusions drawn by the important-others of participants’ true ability are thereby confounded. The results achieved in the phenomenological study were compared with others originating from various quantitative studies, and considerable overlap was found. The experiential richness of the phenomenological results point to a worthwhile methodological strategy for future procrastination research

Isolating Power Amplifiers for Parallel Transmit MRI

A radio frequency parallel transmitter was developed for magnetic resonance imaging. Eight channels of vector modulation and isolating power amplifiers were constructed so that the performance of different amplifier architectures could be investigated. An eight channel system was implemented and tested using both quantitative bench measurements and imaging experiments. The imaging experiments were performed on three separate MR systems at 3T, 4.7T, and 7T at different sites using both B1 shimming and fast modulation techniques. The modulation system implemented is based on vector modulators in order to simplify integration with existing MRI systems. Current Source and Low Output Impedance amplifiers were built and compared in terms of theory of operation, their ability to isolate array coils, and the amount of power they can deliver to a coil. The current source amplifiers function by introducing a high impedance in series with the coil which is series resonant. In contrast, the low output impedance amplifiers present a low impedance to the coil which has a matching network that forms a parallel resonant tank. Both are able to provide isolation, with the current source amplifiers producing in excess of 30dB of isolation and low output impedance amplifiers providing approximately 12.5dB in practical situations. The current source amplifiers can only produce approximately 10A (or between 150W and 300W) of output power because they are not power matched. In contrast, the low output impedance amplifiers can produce roughly 1kW (the device rating) because they are power matched. Ultimately, there is no single best architecture of power amplifiers at this time. Standard amplifiers are useful when only one or two transmit channels are needed and broad-bandedness is valuable. Current source amplifiers are best suited to situations where very high channel counts are needed because of their high isolation. Low output impedance amplifiers are most useful with moderate channel counts because they provide some isolation at moderately high powers

Flow-graph analysis of system calls for exploit detection

One technique of improving computer security is to test an executable for presence of malicious code without running the executable. The present disclosure enables such detection of malicious code by leveraging the observation that system calls (syscalls) are a main pathway for exploits, since syscalls are an important way for a program to interact with an operating system kernel. The disclosure describes techniques to compute a control flow graph for the executable comprising only syscalls. A number of independent control flows are produced from such a control flow graph. Graph analysis/matching techniques are applied to detect exploit patterns in these syscall graphs, e.g., based on matching against known syscall exploit sequences for different vulnerabilities. In this manner, a potentially malicious executable is detected and can be isolated without exposing a computer system to damage

Pressure Sensitive Paint Measurements on 15% Scale Rotor Blades in Hover

This paper describes a proof of concept test to examine the feasibility of using pressure sensitive paint (PSP) to measure the pressure distributions on a rotor in hover. The test apparatus consisted of the US Army 2-meter Rotor Test Stand (2MRTS) and 15% scale swept tip rotor blades. Two camera/rotor separations were examined: 0.76 and 1.35 radii. The outer 15% of each blade was painted with PSP. Intensity and lifetime based PSP measurement techniques were attempted. Data were collected from all blades at thrust coefficients ranging from 0.004 to 0.009