Interactive 3-D Visualization: A tool for seafloor navigation, exploration, and engineering

Recent years have seen remarkable advances in sonar technology, positioning capabilities, and computer processing power that have revolutionized the way we image the seafloor. The massive amounts of data produced by these systems present many challenges but also offer tremendous opportunities in terms of visualization and analysis. We have developed a suite of interactive 3-D visualization and exploration tools specifically designed to facilitate the interpretation and analysis of very large (10\u27s to 100\u27s of megabytes), complex, multi-component spatial data sets. If properly georeferenced and treated, these complex data sets can be presented in a natural and intuitive manner that allows the integration of multiple components each at their inherent level of resolution and without compromising the quantitative nature of the data. Artificial sun-illumination, shading, and 3-D rendering can be used with digital bathymetric data (DTM\u27s) to form natural looking and easily interpretable, yet quantitative, landscapes. Color can be used to represent depth or other parameters (like backscatter or sediment properties) which can be draped over the DTM, or high resolution imagery can be texture mapped on bathymetric data. When combined with interactive analytical tools, this environment has facilitated the use of multibeam sonar and other data sets in a range of geologic, environmental, fisheries, and engineering applications

The morphology and exine ornamentation of fresh pollen from four dipterocarp species in Sabah

Peer reviewedPublisher PD

Coherent vertical electron transport and interface roughness effects in AlGaN/GaN intersubband devices

We investigate electron transport in epitaxially-grown nitride-based resonant tunneling diodes (RTDs) and superlattice sequential tunneling devices. A density-matrix model is developed, and shown to reproduce the experimentally measured features of the current–voltage curves, with its dephasing terms calculated from semi-classical scattering rates. Lifetime broadening effects are shown to have a significant influence in the experimental data. Additionally, it is shown that the interface roughness geometry has a large effect on current magnitude, peak-to-valley ratios and misalignment features; in some cases eliminating negative differential resistance entirely in RTDs. Sequential tunneling device characteristics are dominated by a parasitic current that is most likely to be caused by dislocations, however excellent agreement between the simulated and experimentally measured tunneling current magnitude and alignment bias is demonstrated. This analysis of the effects of scattering lifetimes, contact doping and growth quality on electron transport highlights critical optimization parameters for the development of III-nitride unipolar electronic and optoelectronic devices

A Study of Transport Processes in Ion Exchange Membranes

The major part of this thesis is concerned with the study of transport and diffusion processes in ion-exchange membranes. The ion-exchanger chosen for study was the AWF C60 cation-exchange membrane. Previous studies (1) (2) had suggested that this membrane was more homogeneous than most commercially available exchangers and that it exhibited a high water content and high electrical conductivity, all of which made it a suitable subject for study. It had also been reported that heat treatment of this membrane led to an irreversible expansion of the membrane matrix, producing a membrane with a higher water content and lower flow resistance. (3) The normal and expanded forms of the exchanger were studied in the sodium form in sodium chloride solutions, so that a comparison of the results from the two exchangers might yield information about the effect of expansion on the exchanger properties. In addition to the determination of the basic properties of the exchangers, e.g. water content, physical dimensions, capacity etc. , this study entailed the measurement of the following properties; (1) conductivity, (2) electro-osmotic flow, (3) diffusion of counter- and co-ions, (4) transport numbers of counter- and co-ions. These measurements were made for each membrane in 0.1M, 0.5M 1.0M and 2.0M sodium chloride solutions. Three further experiments were conducted on/ on both membranes under the influence of an electrolyte concentration gradient: salt flow, osmosis and emf measurements were made with concentration gradients of 0.05/0.15 and 0.5/1.5. The results of these experiments have been discussed in terms of the current theories of membrane transport processes. It has been shown that the Nernst-Planck equation, modified to include the effects of convection, can adequately describe the variations in conductivity of the membranes with changing external concentration and the tortuosity factor, 0 (= 1+v w/1-v w), and absolute rate theory, (4) have been used to explain, satisfactorily, the dependence of the ionic diffusion coefficients on the concentration of the external solution. Combining the results of all the transport experiments, it proved possible to carry out a complete analysis of the systems using the theory of non-equilibrium thermodynamics. (5) Examination of the results of this treatment reveals a number of important observations. (1) Where a linear relationship exists between the counter-ion and water transference numbers, as it does for the C60 membranes, a complete analysis of the system can be achieved using the data mentioned above. (2) For the counter-ions, isotope-isotope interaction is an important term and should not be omitted from the calculations as it has been frequently in previous studies. (5) (3)/(3) For the co-ions, the isotope term is not large enough to significantly affect the results, even when the electrolyte uptake is fairly great. (4) Comparison of the results for the two membranes shows that, particularly at 0.1M, the variations in the fluxes of the species, through the membranes, can be almost wholly attributed to the difference in tortuosity of the exchangers. In dilute solutions it has been possible to use some simplify- ing assumptions which have enabled accurate predictions of the salt flow through the membranes to be made. Using the electrolyte uptake data required for the treatment described above, a structural analysis of the membranes has been obtained by employing the method of Glueckauf. (6) This analysis reveals that, although the membranes exhibit inhomogeneity, the degree of heterogeneity is considerably less than that observed in most commonly used ion-exchange membranes. The structural parameters have also been used in conjunction with the co-ion diffusion data, to show that the most continuous regions of the exchangers are those where the fixed charge concentration is very low. The final chapter deals with a study of the inorganic ion-exchanger, hydrous zirconia, both in particle and membrane form. The main feature of this exchanger is the variation in ion- exchange capacity with pH of the external solution. In the chloride form, the counter-ion diffusion coefficients have been determined as a function of the capacity. The results reveal that the/ the diffusion coefficients increase with decreasing capacity, i.e. with increasing distance between the sites of minimum energy, as predicted by the absolute rate theory. (4) Although the agreement is not Quantitative owing, to the assumptions made in the calculations, these results confirm the observations made' for the C60 membranes, that absolute rate theory applied to diffusion processes can be used in the treatment of diffusion in ion-exchangers

T-cell derived acetylcholine aids host defenses during enteric bacterial infection with Citrobacter rodentium.

The regulation of mucosal immune function is critical to host protection from enteric pathogens but is incompletely understood. The nervous system and the neurotransmitter acetylcholine play an integral part in host defense against enteric bacterial pathogens. Here we report that acetylcholine producing-T-cells, as a non-neuronal source of ACh, were recruited to the colon during infection with the mouse pathogen Citrobacter rodentium. These ChAT+ T-cells did not exclusively belong to one Th subset and were able to produce IFNγ, IL-17A and IL-22. To interrogate the possible protective effect of acetylcholine released from these cells during enteric infection, T-cells were rendered deficient in their ability to produce acetylcholine through a conditional gene knockout approach. Significantly increased C. rodentium burden was observed in the colon from conditional KO (cKO) compared to WT mice at 10 days post-infection. This increased bacterial burden in cKO mice was associated with increased expression of the cytokines IL-1β, IL-6, and TNFα, but without significant changes in T-cell and ILC associated IL-17A, IL-22, and IFNγ, or epithelial expression of antimicrobial peptides, compared to WT mice. Despite the increased expression of pro-inflammatory cytokines during C. rodentium infection, inducible nitric oxide synthase (Nos2) expression was significantly reduced in intestinal epithelial cells of ChAT T-cell cKO mice 10 days post-infection. Additionally, a cholinergic agonist enhanced IFNγ-induced Nos2 expression in intestinal epithelial cell in vitro. These findings demonstrated that acetylcholine, produced by specialized T-cells that are recruited during C. rodentium infection, are a key mediator in host-microbe interactions and mucosal defenses

Multimodal analysis of ocular inflammation using the endotoxin-induced uveitis mouse model

Endotoxin-induced uveitis (EIU) in rodents is a model of acute Toll-like receptor 4 (TLR4)-mediated organ inflammation, and has been used to model human anterior uveitis, examine leukocyte trafficking and test novel anti-inflammatory therapeutics. Wider adoption has been limited by the requirement for manual, non-specific, cell-count scoring of histological sections from each eye as a measure of disease severity. Here, we describe a comprehensive and efficient technique that uses ocular dissection and multimodal tissue analysis. This allows matched disease scoring by multicolour flow cytometric analysis of the inflammatory infiltrate, protein analysis on ocular supernatants and qPCR on remnant tissues of the same eye. Dynamic changes in cell populations could be identified and mapped to chemokine and cytokine changes over the course of the model. To validate the technique, dose-responsive suppression of leukocyte infiltration by recombinant interleukin-10 was demonstrated, as well as selective suppression of the monocyte (CD11b+Ly6C+) infiltrate, in mice deficient for either Ccl2 or Ccr2. Optical coherence tomography (OCT) was used for the first time in this model to allow in vivo imaging of infiltrating vitreous cells, and correlated with CD11b+Ly6G+ counts to provide another unique measure of cell populations in the ocular tissue. Multimodal tissue analysis of EIU is proposed as a new standard to improve and broaden the application of this model

MLPerf Inference Benchmark

Machine-learning (ML) hardware and software system demand is burgeoning. Driven by ML applications, the number of different ML inference systems has exploded. Over 100 organizations are building ML inference chips, and the systems that incorporate existing models span at least three orders of magnitude in power consumption and five orders of magnitude in performance; they range from embedded devices to data-center solutions. Fueling the hardware are a dozen or more software frameworks and libraries. The myriad combinations of ML hardware and ML software make assessing ML-system performance in an architecture-neutral, representative, and reproducible manner challenging. There is a clear need for industry-wide standard ML benchmarking and evaluation criteria. MLPerf Inference answers that call. In this paper, we present our benchmarking method for evaluating ML inference systems. Driven by more than 30 organizations as well as more than 200 ML engineers and practitioners, MLPerf prescribes a set of rules and best practices to ensure comparability across systems with wildly differing architectures. The first call for submissions garnered more than 600 reproducible inference-performance measurements from 14 organizations, representing over 30 systems that showcase a wide range of capabilities. The submissions attest to the benchmark's flexibility and adaptability.Comment: ISCA 202

A Challenge for the Development of Malaria Vaccines: Polymorphic Target Antigens

Parasites of the genus Plasmodium cause many hundreds of millions of cases of malaria worldwide optimism that in the future effective vaccination will join the current strategies of preventive and therapeutic uses of antimalarials, and of reduction in human–vector contact, as part of the global malaria control toolkit