13 research outputs found

    Localized temporal decorrelation for video compression

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    Many of the current video compression algorithms perform analysis and coding operations in a block-wise manner. Most of them use a motion compensated DCT algorithm as the basis. Many other codecs, mostly academic and in their infancy and known as Second Generation techniques, utilize region and contour based and model based techniques. Unfortunately, these second-generation methods have not been successful in gaining widespread acceptance in both the standards and the consumer world. Many of them require specialized computationally intensive software and/or hardware. Due to these shortcomings, current block based methods have been finetuned to get better performance at even very low bit rates (sub 64 kbps). Block based motion estimation is the principal mechanism used to compensate for motion between frames in an image sequence. Although current algorithms are fast and quite effective, they fail in compensating for uncovered background areas in a frame. Solutions such as hierarchical motion estimation schemes do not work very well since there is no reference in past, and in some cases, future frames for an uncovered background resulting in the block being transmitted as an intra frame (which requires the most bandwidth among all type of blocks). This thesis intro duces an intermediate stage, which compensates for these isolated uncovered areas. The intermediate stage uses a localized decorrelation technique to reduce frame to frame temporal redundancies. The algorithm can be easily incorporated into exist ing systems to achieve an even better performance and can be easily extended as a scalable video coding architecture. Experimental results show that the algorithm, used in conjunction with motion estimation, is quite effective in reducing temporal redundancies

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    The Collaborative Ocular Tuberculosis Study (COTS)-1: A Multinational Descriptive Review of Tubercular Uveitis in Paediatric Population

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    Purpose To examine disease profile of tubercular uveitis (TBU) in Paediatric population. Methods Among 945 patients of the retrospective multinational study by the Collaborative Ocular Tuberculosis Study (COTS)-1, 29 Paediatric patients diagnosed with TBU were analyzed. Results Mean age of disease presentation was 12.8 (range 4-18 years), with predominance of males (n = 14/20; 70.0%) and Asian ethnicity (n = 25/29; 86.2%). Posterior uveitis (n = 14/28; 50%) was the most frequent uveitis phenotype, with choroidal involvement occurring in 64.7% (n = 11/17). Incidence of optic disc edema and macular edema was higher in children (n = 8/18; 44.4% and n = 5/18; 27.8%, respectively) than in adults (n = 160/942; 16.9% and n = 135/942; 14.3%, respectively). Comparison of optic disc edema between subgroups showed a significant difference (P =.006). All patients received oral corticosteroids, most of them with antitubercular therapy. Treatment failure developed in 4.8% (n = 1/21). Conclusions Children have a more severe inflammatory response to the disease, and an intensive anti-inflammatory therapeutic regimen is required to achieve a positive treatment outcome

    Tubercular uveitis : nuggets from Collaborative Ocular Tuberculosis Study (COTS)-1

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    Background: Tuberculosis (TB) is a major infection that can affect the eye as first and sole presentation without features of systemic disease. Controversy exists regarding diagnosis and management of tubercular uveitis (TBU), further compounded by regional variations in disease expression. Purpose: Collaborative Ocular Tuberculosis Study (COTS)-1 aims to address knowledge deficits through collaboration amongst uveitis specialists across the globe by sharing the data of patients with TBU presented at participating centers from January 2004 to December 2014. Methods: Data collection was facilitated by a novel method of real-time encrypted web-based data entry allowing regular updates as new data and recommendations become available. Results: Information on clinical features, investigation findings, management, and treatment outcomes were reviewed to get an idea about real world scenario. Conclusion: The current review aims to focus on methodology and briefing of published reports from COTS group in COTS-1 study to highlight key messages from this large data

    Visual Morbidity in Ocular Tuberculosis - Collaborative Ocular Tuberculosis Study (COTS)-1: Report #6

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    Objective Aim of the study was to examine extent, natural history, and clinical features associated with visual impairment (VI) in patients diagnosed with ocular tuberculosis (OTB) by the Collaborative Ocular Tuberculosis Study (COTS)-1. Methods Multi-center retrospective cohort study. Main outcomes were VI. Results A total of 302 patients were included in the study, including 175 patients whose data related to BCVA were available throughout the 2 years of follow up. Mean BCVA grossly improved at 12, 18, and 24 months of follow-up (p< .001). Mean BCVA was worse at 12-18th month follow-up for patients treated with ATT versus patients who were not treated with ATT, but patients treated with ATT had a statistically significant improvement in BCVA at the 24-month endpoint. Conclusions OTB is associated with significant visual morbidity, future well-designed prospective studies are warranted to establish the causal association between OTB and visual loss

    Twenty-four Month Outcomes in the Collaborative Ocular Tuberculosis Study (COTS)-1: Defining the "Cure" in Ocular Tuberculosis

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    Purpose To report the clinical findings, anatomical features, and treatment outcomes in subjects with ocular tuberculosis (OTB) at 24 months in the Collaborative Ocular Tuberculosis Study (COTS)-1. Methods Of the 945 subjects included in COTS-1, those who completed a 24-month follow-up after completion of treatment were included. The main outcome measure was a number of patients with treatment failure (TF). Results 228 subjects (120 males; mean age of 42.82 +/- 14.73 years) were included. Most common phenotype of uveitis was posterior (n= 81; 35.53%), and panuveitis (n= 76; 33.33%). Fifty-two patients (22.81%) had TF. On univariable analysis, odds of high TF was observed with bilaterality (OR: 3.46,p= .003), vitreous haze (OR: 2.14,p= .018), and use of immunosuppressive therapies (OR: 5.45,p= .003). However, only bilaterality was significant in the multiple regression model (OR: 2.84;p= .02). Conclusions Majority of subjects (>75%) achieved cure in the COTS-1 at 24-month follow-up. The concept of "cure" may be a valuable clinical endpoint in trials for OTB
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