@article {66, title = {Functional optical coherence tomography at altitude: retinal microvascular perfusion and retinal thickness at 3,800 meters}, journal = {Journal of Applied Physiology}, volume = {133}, year = {2022}, month = {09/2022}, pages = {534{\textemdash}545}, abstract = {Cerebral hypoxia is a serious consequence of several cardiorespiratory illnesses. Measuring the retinal microvasculature at high altitude provides a surrogate for cerebral microvasculature, offering potential insight into cerebral hypoxia in critical illness. In addition, although sex-specific differences in cardiovascular diseases are strongly supported, few have focused on differences in ocular blood flow. We evaluated the retinal microvasculature in males (n = 11) and females (n = 7) using functional optical coherence tomography at baseline (1,130 m) (day 0), following rapid ascent (day 2), and prolonged exposure (day 9) to high altitude (3,800 m). Retinal vascular perfusion density (rVPD; an index of total blood supply), retinal thickness (RT; reflecting vascular and neural tissue volume), and arterial blood were acquired. As a group, rVPD increased on day 2 versus day 0 (P < 0.001) and was inversely related to PaO2 (R2 = 0.45; P = 0.006). By day 9, rVPD recovered to baseline but was significantly lower in males than in females (P = 0.007). RT was not different on day 2 versus day 0 (P > 0.99) but was reduced by day 9 relative to day 0 and day 2 (P < 0.001). RT changes relative to day 0 were inversely related to changes in PaO2 on day 2 (R2 = 0.6; P = 0.001) and day 9 (R2 = 0.4; P = 0.02). RT did not differ between sexes. These data suggest differential time course and regulation of the retina during rapid ascent and prolonged exposure to high altitude and are the first to demonstrate sex-specific differences in rVPD at high altitude. The ability to assess intact microvasculature contiguous with the brain has widespread research and clinical applications.}, issn = {8750-7587}, doi = {10.1152/japplphysiol.00132.2022}, url = {https://doi.org/10.1152/japplphysiol.00132.2022}, author = {Baker, Jacquie and Safarzadeh, Mohammad Amin and Incognito, Anthony V and Jendzjowsky, Nicholas G and Foster, Glen E and Bird, Jordan D and Raj, Satish R and Day, Trevor A and Rickards, Caroline A and Zubieta-DeUrioste, Natalia and Alim, Usman and Wilson, Richard J A} } @article {65, title = {Sub-band Coding of Hexagonal Images}, journal = {Signal Processing: Image Communication}, volume = {99}, year = {2021}, month = {09/2021}, pages = {116494}, doi = {https://doi.org/10.1016/j.image.2021.116494}, url = {https://doi.org/10.1016/j.image.2021.116494}, author = {Md Mamunur Rashid and Usman R. Alim} } @mastersthesis {59, title = {Sub-band Coding of Hexagonal Images}, volume = {MSc}, year = {2019}, month = {09/2019}, school = {University of Calgary}, type = {Unpublished Master{\textquoteright}s Thesis}, address = {Calgary, AB}, abstract = {According to the circle-packing theorem, the packing efficiency of a hexagonal lattice is higher than an equivalent square tessellation. Consequently, in several contexts, hexagonally sampled images compared to their Cartesian counterparts are better at preserving information content. In this thesis, novel mapping techniques alongside the wavelet compression scheme are presented for hexagonal images. Specifically, we introduce two tree-based coding schemes, referred to as SBHex (spirally-mapped branch-coding for hexagonal images) and BBHex (breadth-first block-coding for hexagonal images). Both of these coding schemes respect the geometry of the hexagonal lattice and yield better compression results. Our empirical results show that the proposed algorithms for hexagonal images produce better reconstruction quality at lower bits-per-pixel values compared to the tree-based coding counterparts for the Cartesian grid.}, url = {http://hdl.handle.net/1880/111003}, author = {Md Mamunur Rashid} } @conference {48, title = {3De Interactive Lenses for Visualization in Virtual Environments}, booktitle = {IEEE SciVis Short Papers}, year = {2018}, month = {10/2018}, publisher = {IEEE}, organization = {IEEE}, address = {Berlin, Germany}, doi = {10.1109/SciVis.2018.8823618}, url = {http://hdl.handle.net/1880/110554}, author = {Roberta Cabral Ramos Mota and Allan Rocha and Julio Daniel Silva and Usman Alim and Ehud Sharlin} } @article {47, title = {Decal-Lenses: Interactive Lenses on Surfaces for Multivariate Visualization}, journal = {IEEE Transactions on Visualization and Computer Graphics}, year = {2018}, pages = {1-1}, keywords = {Cameras, Correlation, Data visualization, Decal, Focus+Context, Geometry, Interaction, Lenses, Multivariate, Surfaces, Three-dimensional displays, Two dimensional displays, Visualization}, issn = {1077-2626}, doi = {10.1109/TVCG.2018.2850781}, author = {A. C. A. Rocha and J. D. Silva and U. R. Alim and S. Carpendale and M. C. Sousa} } @mastersthesis {53, title = {GPU-based Compressive Volume Rendering}, volume = {MSc}, year = {2018}, month = {01/2018}, school = {University of Calgary}, address = {Calgary}, doi = {http://dx.doi.org/10.11575/PRISM/5366}, url = {http://hdl.handle.net/1880/106285}, author = {Md. Reza Rabbani} } @article {46, title = {Illustrative Multivariate Visualization for Geological Modelling}, journal = {Computer Graphics Forum (Proceedings of EuroVis 2018)}, volume = {37}, year = {2018}, pages = {465-477}, issn = {1467-8659}, doi = {10.1111/cgf.13434}, author = {Rocha, Allan and Mota, Roberta Cabral Ramos and Hamdi, Hamidreza and Alim, Usman R. and Sousa, Mario Costa} } @proceedings {42, title = {Comparative Visualizations of Noisy and Filtered Blood Flow from 4D PC-MRI Cardiac Datasets}, year = {2017}, month = {10/2017}, pages = {Posters}, address = {Phoenix, AZ}, url = {https://vimeo.com/230837806}, author = {Fahim Hasan Khan and Allan Rocha and Usman Alim} } @article {30, title = {Decal-maps: Real-time Layering of Decals on Surfaces for Multivariate Visualization}, journal = {IEEE Transactions on Visualization and Computer Graphics (Proceedings of IEEE SciVis 2016)}, volume = {23}, year = {2017}, month = {01/2017}, pages = {821 -- 830}, keywords = {Decal, Design, Layering, Multivariate, Real-time, Surface, Visualization}, issn = {1077-2626}, doi = {10.1109/TVCG.2016.2598866}, url = {http://ieeexplore.ieee.org/document/7539320/}, author = {Allan Rocha and Usman Alim and Julio Daniel Silva and Mario Costa Sousa} } @conference {37, title = {Multivariate Visualization of Oceanography Data Using Decals}, booktitle = {Workshop on Visualisation in Environmental Sciences (EnvirVis)}, year = {2017}, month = {06/2017}, publisher = {The Eurographics Association}, organization = {The Eurographics Association}, address = {Barcelona, Spain}, isbn = {978-3-03868-040-6}, doi = {10.2312/envirvis.20171101}, url = {http://dx.doi.org/10.2312/envirvis.20171101}, author = {Allan Rocha and Julio Daniel Silva and Usman R. Alim and Mario Costa Sousa} } @conference {29, title = {Icosahedral Maps for a Multiresolution Representation of Earth Data}, booktitle = {Vision, Modeling and Visualization (VMV)}, volume = { [to appear]}, year = {2016}, month = {10/2016}, publisher = {The Eurographics Association}, organization = {The Eurographics Association}, address = {Bayreuth, Germany}, isbn = {978-3-03868-025-3}, doi = {10.2312/vmv.20161355}, url = {https://diglib.eg.org/handle/10.2312/vmv20161355}, author = {Mohammad Imrul Jubair and Usman R. Alim and Niklas R{\"o}ber and John Clyne and Ali Mahdavi-Amiri} } @proceedings {28, title = {Multiresolution visualization of digital earth data via hexagonal box-spline wavelets}, year = {2015}, month = {10/2015}, publisher = {IEEE}, address = {Chicago, IL}, doi = {10.1109/SciVis.2015.7429508}, url = {http://ieeexplore.ieee.org/document/7429508/}, author = {Mohammad Imrul Jubair and Usman Alim and Niklas R{\"o}ber and John Clyne and Ali Mahdavi-Amiri and Faramarz Samavati} }