Autonomous Robots in Dynamic Indoor Environments: Localization and Person-Following

Autonomous social robots have many tasks that they need to address such as localization, mapping, navigation, person following, place recognition, etc. In this thesis we focus on two key components required for the navigation of autonomous robots namely, person following behaviour and localization in dynamic human environments. We propose three novel approaches to address these components; two approaches for person following and one for indoor localization. A convolutional neural networks based approach and an Ada-boost based approach are developed for person following. We demonstrate the results by showing the tracking accuracy over time for this behaviour. For the localization task, we propose a novel approach which can act as a wrapper for traditional visual odometry based approaches to improve the localization accuracy in dynamic human environments. We evaluate this approach by showing how the performance varies with increasing number of dynamic agents present in the scene. This thesis provides qualitative and quantitative evaluations for each of the approaches proposed and show that we perform better than the current approaches

Synthesis and Characterization of Cobalt Ferrite Nanoparticles

Cobalt ferrite can be synthesized using several techniques. However, to have wide applications in electronic, medical fields etc., the synthesis technique should be simple and inexpensive. The synthesis technique used to prepare nanoparticles should not consume lot of time and energy. Also it should yield narrow particle size distribution and homogeneity in theprepared material. It was observed that surface modification such as with silica coating on the cobalt ferrite will have significant effect on the structural and magnetic properties. It is also observed that, silica coated nanoparticles could be used in biomedical applications (Hong et al., 2013). In this work we have chosen sol-gel method to synthesize pure cobalt ferrite (CoFe2O4) and silica coated (CoFe2O4 / SiO2) nanoparticles. To observe the effect of silicate coating on the structural and magnetic properties of CoFe2O4 we have carried out the present study. CoFe2O4 nanoparticles were synthesized with SiO2 coating and in pure form by sol-gel method. The obtained particle sizes were 24 and 26 nm in both the cases. The X-ray diffraction patterns showed the formation of CoFe2O4 spinel structure without any traces of SiO2 in the prepared samples. The Infrared spectra showed the bands corresponding to tetrahedral andoctahedral sites as feature of typical spinel ferrites and also band due to SiO2. The particle size and morphology of CoFe2O4 / SiO2 was found to be uniform but in the case of pure CoFe2O4 somewhat agglomerated which is accounted for magnetization of ferrites. The magnetization value for CoFe2O4 / SiO2 showed a drastic decrease when compared to pure CoFe2O4 due to presence of non-magnetic coating layer

Adenylyl cyclase 5/6 underlie PIP3 dependent regulation

A wide variety of signaling substances such as hormones, neurotransmitters, odorants and chemokines control intracellular signaling by regulating the production of the second messenger cAMP. By activating Epac, PKA and cyclic nucleotide-gated ion channels, the production of cAMP alters a wide range of biological processes including cell division and metabolism. A number of GPCRs controls intracellular cAMP levels via stimulatory or inhibitory G proteins via adenylyl cyclases. The function of the broadly expressed AC5 and AC6 is enhanced by stimulatory (Gαs) or attenuated by inhibitory (Gαi) G proteins. Mechanistically both inhibition and stimulation is mediated via a direct protein-protein interaction. In addition to this direct regulation, several previous studies reported a cAMP rebound stimulation after withdrawal of Gi stimulation in cardiac myocytes for which the mechanism is debated (Hartzell, 1988; Wang & Lipsius, 1995). A similar cAMP rebound response was observed previously in our lab after termination of α2A-AR adrenergic receptor activation in HEK293T cells (Markus et al., 2013). The present study was aimed at investigating mechanisms underlying Gi-induced cAMP rebound effects. Many genetically encoded biosensors have been developed based on fluorescence resonance energy transfer (FRET) to visualize the spatiotemporal dynamics of various intracellular signals including second messengers. FRET-based cAMP biosensor (Epac1-camps) as well as heterologous overexpression system was used to investigate the mechanisms underlying Gi-mediated cAMP rebound stimulation in cardiac myocytes and also in heterologous expression system. When studying the mechanism of the long-known phenomenon of cAMP rebound stimulation after withdrawal of Gi stimulation in cardiac myocytes, we observed a PTX-sensitive/Gi-mediated/ adenylyl cyclase (type 5/6)/ cAMP-dependent pathway for this cAMP rebound stimulation. In addition, we observed that inhibition of Gβγ by gallein led to an attenuation of the AC5- mediated cAMP rebound response, although, overexpression of AC4 did not produce additional cAMP stimulation. This implies that different Gβγ-mediated signaling pathways may exist. Interestingly, we observed that PI3K inhibitor attenuates AC5/6-dependent cAMP rebound effects. This indicated that Gi-mediated cAMP rebound response was mediated via the PI3K-dependent pathway. Indeed, overexpression of PIP3-specific phosphatase PTEN confirmed that PIP3 itself either directly or indirectly mediated Gi-dependent cAMP rebound responses. Additionally, inhibition of PIP2-specific phosphatase SHIP and downstream events of PIP3-dependent regulation of Akt further confirm the influence of PIP3 on cAMP rebound levels. Indeed, surpassing Gi-mediated PI3K activation through PDGF-receptor stimulation strengthens this pathway. In addition, we confirmed that inhibition of PI3K also prevented cAMP rebound response after withdrawal of ACh in atrial myocytes. We suppose that the novel PIP3 dependent regulation of AC5/6 might represent a missing mechanism that explains physiological phenomena such as post vagal tachycardia

Techniques for Ocular Biometric Recognition Under Non-ideal Conditions

The use of the ocular region as a biometric cue has gained considerable traction due to recent advances in automated iris recognition. However, a multitude of factors can negatively impact ocular recognition performance under unconstrained conditions (e.g., non-uniform illumination, occlusions, motion blur, image resolution, etc.). This dissertation develops techniques to perform iris and ocular recognition under challenging conditions. The first contribution is an image-level fusion scheme to improve iris recognition performance in low-resolution videos. Information fusion is facilitated by the use of Principal Components Transform (PCT), thereby requiring modest computational efforts. The proposed approach provides improved recognition accuracy when low-resolution iris images are compared against high-resolution iris images. The second contribution is a study demonstrating the effectiveness of the ocular region in improving face recognition under plastic surgery. A score-level fusion approach that combines information from the face and ocular regions is proposed. The proposed approach, unlike other previous methods in this application, is not learning-based, and has modest computational requirements while resulting in better recognition performance. The third contribution is a study on matching ocular regions extracted from RGB face images against that of near-infrared iris images. Face and iris images are typically acquired using sensors operating in visible and near-infrared wavelengths of light, respectively. To this end, a sparse representation approach which generates a joint dictionary from corresponding pairs of face and iris images is designed. The proposed joint dictionary approach is observed to outperform classical ocular recognition techniques. In summary, the techniques presented in this dissertation can be used to improve iris and ocular recognition in practical, unconstrained environments

Advanced process to embed optical fiber sensors into casting mold for smart manufacturing

Optical fiber sensors embedded in metals with distributed sensing can sense temperature at multiple points with single fiber. This is useful for smart manufacturing like structural health monitoring in aerospace industry and smart molds in manufacturing plants. There is a huge difference in thermal coefficient of expansion for fiber and metal. This is the reason for the increase in sensitivity for embedded fiber sensors. However, at high temperatures, the stress on the fiber increases, eventually damaging the sensor. The fiber-metal interface determines the sensor performance. A tight interface results in high sensitivity and a gap in the interface enhances sensing range. There is a dilemma to choose either high sensitivity or high sensing range. The objective of this study is to enhance the interface to have both high sensitivity and high sensing range which can be used for casting application. Extrinsic Fabry-Perot interferometer (EFPI) sensors with a single sensing point and cavity length around 50 μm are embedded into copper substrate using electrodeposition. The embedded sensors are 300 μm deep from the surface. Three different interface: chemical plated, copper painted, and dual-layer interface, were tested. The results show that dual-layer interface can provide both high sensitivity of 45 pm/°C and high sensing range of 700°C at the same time, which overcomes sensitivity-sensing range dilemma. The analysis shows that one layer in the dual-layer interface increases the longitudinal strain for sensitivity and the other layer reduces the radial strain which enhances the sensing range. This new dual-layer interface developed in this research can have high sensitivity and high sensing range at the same time. Aluminum casting was done to test the effectiveness of the dual-layer interface. The cooling curve data from the EFPI sensor is consistent with the thermocouple data --Abstract, page iv

Outbreaks of aflatoxicoses in India

Mycotoxins particularly aflatoxins are gaining increasing importance due to their deleterious effects on human and animal health and also due to ubiquitous  presence  of aflatoxigenic fungi in all the agricultural commodities under field and storage conditions. In general, aflatoxins occur more frequently in tropical  countries  because of high temperature, moisture, unseasonal rains and flash  floods.  Poor harvesting practices, improper storage and less than optimal  conditions during transport and marketing can also contribute to mycotoxin production. Chronic health risks are particularly prevalent in India where the diets of people are highly prone to aflatoxigenic fungi and aflatoxins. The present paper reviews the disease outbreaks of aflatoxicoses in India due to the ingestion of contaminated food and feed with aflatoxins. One of the first outbreaks of  aflatoxicosis was reported from western India during 1974 with 106 deaths of indigenous people whose staple food was maize. This is perhaps the first report directly incriminating aflatoxin in food as a human health hazard at the indigenous community level. An independent study of the same outbreak was carried out  subsequently also indicated that the aflatoxins were the major cause of the  outbreak. Indian childhood cirrhosis, a clinical condition mainly confined to the Indian subcontinent has been attributed to aflatoxin   contamination. They also found a correlation between aflatoxin contamination and fungal load on the one hand and hepatomegaly in children on the other in south Canara district of Karnataka. Another outbreak of toxic hepatitis affecting both humans and dogs was reported in India during 1974. Heavy mortality in chicks in Chittoor district of Andhra Pradesh was reported in 1982 due to aflatoxicosis. Another outbreak of aflatoxicosis in commercial poultry farms was also reported in the same district with hundred percent mortality. A case of aflatoxicosis in Murrah buffaloes from Andhra Pradesh was also reported. Occurrence of aflatoxicosis in poultry in Mysore state was first recognized in 1966 where 2219 chicks died in one week. Subsequently, several sporadic incidences were found in various poultry farms in Karnataka. Most of the outbreaks of aflatoxicoses described here are a  consequence of ingestion of food that is contaminated with aflatoxins. Disease outbreaks due to aflatoxins continue to be problems of significant public health concern in India as long as people will consume contaminated food. The strict control of food quality is therefore  necessary to avoid such incidences.Keywords:  Aflatoxicoses, Aflatoxins, Fungi, Food qualit

Incidence, risk factors and outcomes of de novo malignancies post liver transplantation

Liver transplantation (LT) is associated with a 2 to 7 fold higher, age and gender adjusted, risk of de novo malignancy. The overall incidence of de novo malignancy post LT ranges from 2.2% to 26%, and 5 and 10 years incidence rates are estimated at 10% to 14.6% and 20% to 32%, respectively. The main risk factors for de novo malignancy include immunosuppression with impaired immunosurveillance, and a number of patient factors which include; age, latent oncogenic viral infections, tobacco and alcohol use history, and underlying liver disease. The most common cancers after LT are non-melanoma skin cancers, accounting for approximately 37% of de novo malignancies, with a noted increase in the ratio of squamous to basal cell cancers. While these types of skin cancer do not impact patient survival, post-transplant lymphoproliferative disorders and solid organ cancer, accounting for 25% and 48% of malignancies, are associated with increased mortality. Patients developing these types of cancer are diagnosed at more advanced stages, and their cancers behave more aggressively compared with the general population. Patients undergoing LT for primary sclerosing cholangitis (particularly with inflammatory bowel disease) and alcoholic liver disease have high rates of malignancies compared with patients undergoing LT for other indications. These populations are at particular risk for gastrointestinal and aerodigestive cancers respectively. Counseling smoking cessation, skin protection from sun exposure and routine clinical follow-up are the current approach in practice. There are no standardized surveillance protocol, but available data suggests that regimented surveillance strategies are needed and capable of yielding cancer diagnosis at earlier stages with better resulting survival. Evidence-based strategies are needed to guide optimal surveillance and safe minimization of immunosuppression