Citation: Zahid S, Dolz-Marco R, Freund KB, et al. Fractal dimensional analysis of optical coherence tomography angiography in eyes with diabetic retinopathy. Invest Ophthalmol Vis Sci. 2016;57:4940-4947. DOI:10.1167/iovs.16-19656 PURPOSE. We used fractal dimensional analysis to analyze retinal vascular disease burden in eyes with diabetic retinopathy using spectral-domain optical coherence tomography angiography (OCTA). METHODS.A retrospective study was performed of 13 eyes with diabetic retinopathy without diabetic macular edema and 56 control eyes. Optical coherence tomography angiography images were acquired using the RTVue XR Avanti. Automated segmentation was obtained through the superficial and deep capillary plexuses for each eye. Grayscale OCTA images were standardized and binarized using ImageJ. Fractal box-counting analyses were performed using Fractalyse. Fractal dimensions (FD) as well as software-generated vascular density analyses of the superficial and deep capillary plexuses were compared between diabetic and control eyes using 2-tailed t-tests and 1-way multivariate ANOVA (MANOVA) analyses. RESULTS.The superficial and deep plexuses from diabetic and control eyes were analyzed. The average FD for diabetic eyes was significantly lower than control eyes for the superficial (P ¼ 4.513 3 10 À3 ) and deep (P ¼ 2.653 3 10 À3 ) capillary plexuses. In diabetic eyes, the vascular density also was significantly reduced in the superficial (P ¼ 8.068 3 10 À5 ) and deep (P ¼ 3.120 3 10 À6 ) capillary plexuses. One-way MANOVA showed a significant difference between diabetic and control eyes.CONCLUSIONS. The OCTA FD is significantly reduced in the superficial and deep capillary plexuses in eyes with diabetic retinopathy. Applying fractal analysis to OCTA imaging holds the potential to establish quantitative parameters for microvascular pathology.

We examine the fraction of massive (M * > 10 10 M ⊙ ), compact star-forming galaxies (cSFGs) that host an active galactic nucleus (AGN) at z ∼ 2. These cSFGs are likely the direct progenitors of the compact quiescent galaxies observed at this epoch, which are the first population of passive galaxies to appear in large numbers in the early Universe. We identify cSFGs that host an AGN using a combination of Hubble WFC3 imaging and Chandra X-ray observations in four fields: the Chandra Deep Fields, the Extended Groth Strip, and the UKIDSS Ultra Deep Survey field. We find that 39.2 +3.9 −3.6 % (65/166) of cSFGs at 1.4 < z < 3.0 host an X-ray detected AGN. This fraction is 3.2 times higher than the incidence of AGN in extended star-forming galaxies with similar masses at these redshifts. This difference is significant at the 6.2σ level. Our results are consistent with models in which cSFGs are formed through a dissipative contraction that triggers a compact starburst and concurrent growth of the central black hole. We also discuss our findings in the context of cosmological galaxy evolution simulations that require feedback energy to rapidly quench cSFGs. We show that the AGN fraction peaks precisely where energy injection is needed to reproduce the decline in the number density of cSFGs with redshift. Our results suggest that the first abundant population of massive, quenched galaxies emerged directly following a phase of elevated supermassive black hole growth and further hints at a possible connection between AGN and the rapid quenching of star formation in these galaxies.

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The optical coherence tomography angiography FD is significantly lower in both superficial and deep capillary plexuses in eyes with all stages studied of diabetic retinopathy. The results were more often significant for the deep capillary plexus. The use of fractal analysis provides an objective criterion to assess microvascular disease burden in diabetic retinopathy.

PurposePervasive mobile games (PMG) expand the game context into the real world, spatially, temporally and socially. The most prominent example to date is Pokémon Go (PGo), which in the first 12 months of its launch achieved over 800 million downloads and huge revenues for Pokémon, its majority owner Nintendo, and its developer Niantic. Like many mobile apps and innovative services, PGo's revenue structure requires continual usage (through in-app purchases and sponsorships) as it is free to download. Thus, as many players discontinued after initial adoption, substantial drops in Nintendo's share price occurred alongside the damage to brand equity. Such a case highlights the need to extend scholarship beyond traditional ‘adoption’ and begin to truly illustrate and explain the consumer behaviour phenomenon of ‘discontinuance’, particularly in the emerging and lucrative domain of PMGs.Design/methodology/approachLike many emerging marketing channels before it, large-scale discontinuance of PGo occurred and still remains unexplained in the academic literature. Herein, we address this shortcoming through a consumer case study methodology analysing a variety of data sources pertaining to PGo in Australia.FindingsThe development of the P2D_PMG model provides a new conceptual framework to illustrate the distinct forms discontinuance manifests in, for the first time. Scholarly rigour of the P2D_PMGs is achieved through validating and extending Soliman and Rinta-Kahila's (2020) framework for ‘discontinuance’ through its five forms. These forms are revealed as access and on-boarding (rejection), disconfirmation and hedonic adaptation (regressive discontinuance), technological, social, third parties, and personal issues (quitting), re-occurrences of hedonic adaptation (temporary), and alternatives and iterations (replacement).Originality/valueConceptual contributions are made in developing a model to explain what drives PMG discontinuance and when it occurs. This is particularly crucial for products with revenue structures built on continual usage, instead of initial adoption. In deriving data from actual players and aggregate user behaviour over an extended time period, the innovative case study methodology validates new discontinuance research in a manner other methods cannot. Managerial implications highlight the importance of CX, alpha/beta testing, promotion and research, gameplay design and collaboration/community engagement.