Adaptive visual sampling

PhDVarious visual tasks may be analysed in the context of sampling from the visual field. In visual psychophysics, human visual sampling strategies have often been shown at a high-level to be driven by various information and resource related factors such as the limited capacity of the human cognitive system, the quality of information gathered, its relevance in context and the associated efficiency of recovering it. At a lower-level, we interpret many computer vision tasks to be rooted in similar notions of contextually-relevant, dynamic sampling strategies which are geared towards the filtering of pixel samples to perform reliable object association. In the context of object tracking, the reliability of such endeavours is fundamentally rooted in the continuing relevance of object models used for such filtering, a requirement complicated by realworld conditions such as dynamic lighting that inconveniently and frequently cause their rapid obsolescence. In the context of recognition, performance can be hindered by the lack of learned context-dependent strategies that satisfactorily filter out samples that are irrelevant or blunt the potency of models used for discrimination. In this thesis we interpret the problems of visual tracking and recognition in terms of dynamic spatial and featural sampling strategies and, in this vein, present three frameworks that build on previous methods to provide a more flexible and effective approach. Firstly, we propose an adaptive spatial sampling strategy framework to maintain statistical object models for real-time robust tracking under changing lighting conditions. We employ colour features in experiments to demonstrate its effectiveness. The framework consists of five parts: (a) Gaussian mixture models for semi-parametric modelling of the colour distributions of multicolour objects; (b) a constructive algorithm that uses cross-validation for automatically determining the number of components for a Gaussian mixture given a sample set of object colours; (c) a sampling strategy for performing fast tracking using colour models; (d) a Bayesian formulation enabling models of object and the environment to be employed together in filtering samples by discrimination; and (e) a selectively-adaptive mechanism to enable colour models to cope with changing conditions and permit more robust tracking. Secondly, we extend the concept to an adaptive spatial and featural sampling strategy to deal with very difficult conditions such as small target objects in cluttered environments undergoing severe lighting fluctuations and extreme occlusions. This builds on previous work on dynamic feature selection during tracking by reducing redundancy in features selected at each stage as well as more naturally balancing short-term and long-term evidence, the latter to facilitate model rigidity under sharp, temporary changes such as occlusion whilst permitting model flexibility under slower, long-term changes such as varying lighting conditions. This framework consists of two parts: (a) Attribute-based Feature Ranking (AFR) which combines two attribute measures; discriminability and independence to other features; and (b) Multiple Selectively-adaptive Feature Models (MSFM) which involves maintaining a dynamic feature reference of target object appearance. We call this framework Adaptive Multi-feature Association (AMA). Finally, we present an adaptive spatial and featural sampling strategy that extends established Local Binary Pattern (LBP) methods and overcomes many severe limitations of the traditional approach such as limited spatial support, restricted sample sets and ad hoc joint and disjoint statistical distributions that may fail to capture important structure. Our framework enables more compact, descriptive LBP type models to be constructed which may be employed in conjunction with many existing LBP techniques to improve their performance without modification. The framework consists of two parts: (a) a new LBP-type model known as Multiscale Selected Local Binary Features (MSLBF); and (b) a novel binary feature selection algorithm called Binary Histogram Intersection Minimisation (BHIM) which is shown to be more powerful than established methods used for binary feature selection such as Conditional Mutual Information Maximisation (CMIM) and AdaBoost

Intramural hemotoma presenting as acute coronary syndrome: The importance of intravascular ultrasound

Intramural hematoma in major coronary epicardial vessels is a rare cause of chest pain. Afflicted individuals may present with acute coronary syndrome (ACS) or even sudden cardiac death. Spontaneous, isolated intramural hematoma may occur in the absence of associated intimal dissection. In this situation, lesions may be angiographically indistinguishable from ruptured atherosclerotic plaque. Intravascular ultrasound is important in the accurate diagnosis of isolated intramural hematoma. Although coronary stenting may be required in the presence of ongoing ischemia, intramural hematoma may be successfully managed medically. We describe the case of a middle-aged woman who presented with ACS due to an intramural hematoma and discuss the diagnosis and management of this rare illness

Minimal hepatic encephalopathy in children with extra hepatic portal vein obstruction.

INTRODUCTION : Extra-Hepatic Portal Vein Obstruction is one of the vascular disorders of the liver. It is said to occur when there is obstruction to the extra hepatic part of the portal vein with or without the involvement of the intrahepatic part, splenic vein or the superior mesenteric vein. In children, it accounts for nearly 70% of the cases of portal hypertension and is the commonest cause of upper GI bleed in them. In Adults, EHPVO is responsible for nearly one-third of cases of portal hypertension. Etiologically, EHPVO is a heterogeneous disease and the cause varies with respect to age and geographic location. Umbilical sepsis, umbilical vein catheterisation, intra-abdominal sepsis, congenital malformations of the portal vein, hypercoagulable states, trauma have all been documented as possible etiological factors. However, despite the best of efforts, a clear aetiology remains elusive in a vast majority of cases. Patients with EHPVO can present in two clinical forms: 1) Acute form and 2) Chronic form, with the latter being distinctly more common than the former. In its acute form, patients may present with acute abdominal pain sometimes associated with low grade fever and rarely as transient ascites. In its more common Chronic form, patients present with variceal bleeding, moderate to massive splenomegaly and features suggestive of hypersplenism. Rarely patients may present with jaundice secondary to portal biliopathy. This study aims to evaluate children with EHPVO for the existence of MHE by using Psychometric tests and Critical flicker Frequency. I believe that establishing the presence of MHE in children with EHPVO would lay the foundation for treatment modalities, with the potential to improve scholastic performance and overall intellectual and psychological development of these children. AIMS OF THE STUDY : To study the clinical profile of children with Extra-Hepatic Portal Vein Obstruction, To study the prevalence of minimal hepatic encephalopathy in these children, using 1. Psychometric Tests, 2. Critical Flicker Frequency. CONCLUSIONS : 1. Minimal Hepatic Encephalopathy does exist in children with Extra Hepatic Portal Vein Obstruction. 2. Prevalence is as high as 50% when psychometric tests are used and 46% when Critical Flicker Fusion is used. 3. Digit Symbol Test, Number Connection Test - B are highly sensitive among psychometric tests in detecting Minimal Hepatic Encephalopathy and can be used as initial screening tests. 4. Critical Flicker Fusion has a good sensitivity and specificity in detecting Minimal Hepatic Encephalopathy and correlated well with psychometric tests

Non-Variceal Upper Gastrointestinal Haemorrhage: Clinical Profile and Application of Rockall Prognostic Score

CONCLUSION: 1. Peptic Ulcer Disease is the most common cause of Nonvariceal Upper Gastrointestinal Haemorrhage. 2. Though among patients with peptic ulcer disease the commonest lesion found was gastric ulcer, duodenal ulcers had a greater chance of re-bleed and having a protracted course. 3. Increasing age was associated with increased occurrence of rebleed and an increased duration of hospitalisation. 4. Non variceal bleeding was more common in males. 5. NSAID intake and alcohol are preventable predisposing factors for Non-variceal Upper Gastrointestinal Haemorrhage. 6. Rockall score is useful in predicting the prognosis of the patients with NVUGIH. It correlates well with the re-bleed, duration of hospitalisation, transfusion requirements and outcome

Biochemical characterization of protease activity of Nsp3 from SARS-CoV-2 and its inhibition by nanobodies

Of the 16 non-structural proteins (Nsps) encoded by SARS CoV-2, Nsp3 is the largest and plays important roles in the viral life cycle. Being a large, multidomain, transmembrane protein, Nsp3 has been the most challenging Nsp to characterize. Encoded within Nsp3 is the papain-like protease domain (PLpro) that cleaves not only the viral polypeptide but also K48-linked polyubiquitin and the ubiquitin-like modifier, ISG15, from host cell proteins. We here compare the interactors of PLpro and Nsp3 and find a largely overlapping interactome. Intriguingly, we find that near full length Nsp3 is a more active protease compared to the minimal catalytic domain of PLpro. Using a MALDI-TOF based assay, we screen 1971 approved clinical compounds and identify five compounds that inhibit PLpro with IC50s in the low micromolar range but showed cross reactivity with other human deubiquitinases and had no significant antiviral activity in cellular SARS-CoV-2 infection assays. We therefore looked for alternative methods to block PLpro activity and engineered competitive nanobodies that bind to PLpro at the substrate binding site with nanomolar affinity thus inhibiting the enzyme. Our work highlights the importance of studying Nsp3 and provides tools and valuable insights to investigate Nsp3 biology during the viral infection cycle

Mutations involving the SRY-related gene SOX8 are associated with a spectrum of human reproductive anomalies.

© The Author(s) 2018. Published by Oxford University Press. All rights reserved. SOX8 is an HMG-box transcription factor closely related to SRY and SOX9. Deletion of the gene encoding Sox8 in mice causes reproductive dysfunction but the role of SOX8 in humans is unknown. Here, we show that SOX8 is expressed in the somatic cells of the early developing gonad in the human and influences human sex determination. We identified two individuals with 46, XY disorders/differences in sex development (DSD) and chromosomal rearrangements encompassing the SOX8 locus and a third individual with 46, XY DSD and a missense mutation in the HMG-box of SOX8. In vitro functional assays indicate that this mutation alters the biological activity of the protein. As an emerging body of evidence suggests that DSDs and infertility can have common etiologies, we also analysed SOX8 in a cohort of infertile men (n=274) and two independent cohorts of women with primary ovarian insufficiency (POI; n=153 and n=104). SOX8 mutations were found at increased frequency in oligozoospermic men (3.5%; P < 0.05) and POI (5.06%; P=4.5×10 -5 ) as compared with fertile/normospermic control populations (0.74%). The mutant proteins identified altered SOX8 biological activity as compared with the wild-type protein. These data demonstrate that SOX8 plays an important role in human reproduction and SOX8 mutations contribute to a spectrum of phenotypes including 46, XY DSD, male infertility and 46, XX POI.Link_to_subscribed_fulltex