Abstract

The task of a query-by-example spoken term detection (QbE-STD) is to find a spoken query within a spoken audio database. A key aspect of QbE-STD is to enable searching in multi-lingual and multi-speaker audio data. A traditional QbE-STD approach is to convert spoken audio into a sequence of symbols using automatic speech recognition (ASR) and then perform text based search. ASR-based techniques assume the availability of labelled data for training the acoustic and language models. Such approaches are not scalable for languages where there is no availability or the resources to build an ASR. To overcome this limitation, zero prior knowledge is assumed about the language of the spoken audio, and thus template matching algorithms such as dynamic time warping (DTW) are exploited for QbE-STD. For QbE-STD, Gaussian posteriorgrams are a popular feature representation as they do not require labelled data. However, Gaussian posteriorgrams can only represent a limited acoustic information of the spoken audio and thus a limitation. An alternative feature representation to Gaussian posteriorgrams is phone posteriorgrams. To obtain phone posteriorgrams we require labelled data from rich resource languages to train the models. However, phone classes are not universal and thus do not perform well when there is a language mismatch. In this thesis, we address the issues of developing a DTW-based algorithm for QbE-STD search on low resource languages and deriving language independent features using rich resource languages for feature representation of speech. The contributions of this thesis are as follows: 1) We investigate the use of a DTW-based algorithm referred to as non-segmental DTW (NS- DTW), with a computational upper bound of O(mn) and analyze the performance of QbE- STD with Gaussian posteriorgrams obtained from spectral and temporal features of the speech signal. 2) We introduce another variant of NS-DTW called fast NS-DTW (FNS-DTW) which uses reduced feature vectors for search. With a reduction factor of α ∈ N, we show that the computational upper bound for FNS-DTW is O(mn/α^2) which is faster than NS-DTW. We also explore explore the use of graphical processing units (GPUs) to improve the speed of NS-DTW and its variants to enable searching in large databases in real time. 3) We investigate the use of language independent representations of speech such as articulatory class information for QbE-STD search. We use articulatory information and their derivatives such as bottle-neck (BN) features (also referred to as articulatory BN features) for QbE-STD. We obtain Gaussian posteriorgrams of articulatory BN features in tandem with the acoustic parameters to perform the search. 4) As an alternative to phone and articulatory classes of speech, we also explore acoustic classes of speech for QbE-STD. We define the acoustic classes as the classes in the space represented by the acoustic parameters of speech such as frequency domain linear prediction cepstral coefficients (FDLP). An advantage of using acoustic classes over articulatory or phone classes is that they can be obtained using unsupervised clustering algorithms. We use acoustic classes of speech to derive BN features and to build acoustic models for QbE-STD search. In this thesis, the techniques explored in developing DTW-based algorithms and use of feature representation derived from speech classes such as phone, articulatory and acoustic classes can be used to rapidly build QbE-STD search systems. These techniques will enable in building search systems for low resource and less spoken languages and thereby help in reducing the language barrier for information access.

Abstract

In this paper, we solve the traditional problem of autonomous Localization and Mapping by inter- leaving planning for exploring unknown environments by a mobile robot and Simultaneous Localization and Mapping (SLAM). We denote such planned SLAM systems as SPLAM (Simultaneous Planning Localization and Mapping). The main aim of SPLAM is to plan paths for the SLAM process such that the robot and map uncertainty upon execution of the path remains minimum and tractable. The planning is interleaved with SLAM and hence the terminology SPLAM. While typical SPLAM routines find paths when the robot traverses amidst known regions of the constructed map, herein we use the SPLAM formulation for an exploration like situation. Exploration is carried out through a frontier based approach where we identify multiple frontiers in the known map. Using Randomized Trajectory Generation techniques we calculate various possible trajectories to all the known frontiers. A practical SPLAM system must be fast and also be able to handle presence of dynamic objects in the environment. We’ve provided solutions to these two problems separately. For developing a fast planning system we introduce a novel strategy for selecting the trajectory which mimics Fast SLAM, selects a trajectory for robot motion that will minimize the map and robot state covariance. By using a Fast SLAM like approach for selecting frontiers we are able to decouple the robot and landmark covariance resulting in a faster selection of next best location, while maintaining the same kind of robustness of an EKF based SPLAM framework. We then compare our results with Shortest Path Algorithm and EKF based Planning. We show significant reduction in covariance when compared with shortest frontier first approach, while the uncertainties are comparable to EKF-SPLAM albeit at much faster planning times. For planning in Dynamic Environments while the typical planning methods for Dynamic Environments involve filtering the dynamic objects and then planning for the static environment thereafter obtained, we’ve developed a novel planning algorithm which is intelligently able to decide whether to keep or discard the dynamic objects. If we are able to make use of them to aide localization they are kept in the SLAM framework, but if found hindering the localization they are discarded. For this, along with selecting one of the trajectories generated through the Trajectory Generation system, we also comes up with an action policy. This action policy dictates what action, from a given set of actions, will the robot take at each node of the trajectory. Also for the process of SLAM which is intermediate to planning, we devise a EKF-SLAM based framework which is capable of incorporating Dynamic Objects as opposed to the traditional SLAM methods. We then compare our results with a method that unilaterally filters all moving objects, which we call as the dynamic object filtering method or simply filtering method in short. We show significant reduction in robot and map uncertainty when compared with the dynamic object filtering planning method, for both simulated and real environments.

Abstract

"A typical microwave Synthetic Aperture Radar (SAR) is an aerial based system for high resolution imaging of terrain. In contrast to an optical imaging system, its operation is not limited to daytime and its performance is not adversely affected by severe weather conditions like fog, snow or clouds. A conventional Side-looking Synthetic Aperture Radar provides high azimuth resolution but in the side looking mode. In situations like aircraft landing or ground vehicle piloting, the radar has to image a forward swath. But the SAR in the forward-looking mode not only suffers from target ambiguities, but more importantly, it also cannot yield an azimuth resolution comparable to that of the side looking mode. In this thesis, we explore the possibility of an imaging system, which draws on the principle of functioning of an SAR and is able to image the terrain ahead of a vehicle. Three approaches are proposed and analyzed. The first approach, termed as Azimuth Triangulation Method, abbreviated as ATM, deploys a multiple antenna SAR to solve the problem of low azimuth resolution and high azimuth ambiguity in a forward-looking SAR (FSAR). As is to be expected, the performance improves with a larger number of antennas. In view of the complexity of the system based on the ATM approach, as the second approach, a SAR in a squint-mode is considered. For purposes of comparison, a SAR in the forward mode is also simulated. The simulations performed for the three approaches indicate while the range resolution is same in all the cases (approximately 0.3 m, under the stipulated conditions of simulations) the azimuth resolution varies considerably. The ATM approach achieved an azimuth resolution of approximately 12m, while the forward-mode SAR and the squint-mode SAR yielded an azimuth resolution of 18m and 1.5m respectively."

Abstract

Quantum Information Processing (QIP) is a branch of science that investigates the use of quantum mechanics for communication and computation purposes. Quantum information has power to far exceed the capabilities of traditional “classical” information. It exploits fundamental quantum features like superposition, entanglement and non-locality in information processing. In this thesis, we report our work on two different aspects of QIP. The first lies in the domain of quantum cryptography, namely sequential quantum secret sharing, and second on the phenomena of broadcasting of correlations, which can be extensively used for decompression of quantum correlation. In QIP, entanglement proves to be an invaluable resource for carrying out various cryptographic protocols. Quantum secret sharing (QSS), an analogous quantum version of Shamir’s classical secret sharing scheme, is one such cryptographic protocol, where the sender shares a secret message between other parties in such a way that none of them can reveal the secret without the collaboration of others. We provide a (n,n)-threshold protocol for sequential secret sharing of quantum information and then optimize it under both an idealistic situation and a realistic situation, where we have a noisy environment.This scheme refers to a situation where the dealer is not having all the secrets, at the start of the protocol; however if the dealer wishes to share secrets at subsequent stages she/he can realize it with the help of our protocol. We also extend it to n > 3 parties. Thereafter, we consider a much more realistic situation where the sharing of qubits takes place through two kinds of noisy channels, namely the phase damping channel (PDC) and the amplitude damping channel (ADC). We observe that in the presence of noise, the fidelity of sequential secret sharing at the (k)th iteration is independent of the effect of noise at the (k − 1)th iteration. In case of ADC, we find that the average fidelity of secret sharing drops down to 1/2 which is equivalent to a random guess of the quantum secret. Finally, we employ weak measurements and its reversal to enhance the average fidelity. This increase can be achieved with a certain trade-off with the success probability of weak measurements. It often happens in quantum information processing that we are provided with an entangled pair and asked to create more by using quantum operations. This exigency arises from the fact that sometimes there is a higher priority on increasing the number of participants in information processing task than on the efficiency of it. In this work, we extensively study the problem of broadcasting of quantum correlations. This includes broadcasting of quantum entanglement as well as correlations that go beyond the notion of entanglement. It is quite well known from the “No-Broadcasting theorem" that perfect broadcasting of quantum correlation is not possible. However it does not rule out the possibility of partial broadcasting of correlations where we can get lesser correlated states from a given correlated state. In order to have a holistic view of broadcasting, we investigate this problem by starting with most general representation of two qubit mixed states in terms of the Bloch vectors. As a cloning transformation we have used universal symmetric optimal Buzek-Hillery (B-H) cloner both locally and nonlocally. More specifically, we obtain a set of ranges in terms of Bloch vectors for which broadcasting of entanglement will be possible. In addition to the idea of broadcasting of entanglement for general two qubit mixed states, we explore broadcasting of quantum correlations that go beyond entanglement with the help of both local and nonlocal cloners. Remarkably, we find that it is impossible to even partially broadcast such correlations by using quantum copying machines whether locally or globally. Taking two different types Buzek-Hillery quantum cloners (state dependent and state independent) we analytically prove the impossibility of even partial broadcasting of correlation. Lastly, we generalize this impossibility result for any symmetric or asymmetric cloning machines as well. This result brings out a fundamental difference between the correlation defined from the perspective of entanglement and the correlation measure which claims to go beyond entanglement. In a nutshell, our work presents some interesting phenomena in quantum information and cryptography. The work is directed to find new methodologies which will make the protocol for sharing of quantum secret more efficient, comprehensive and stable in the perspective of realistic scenarios. It is also aimed at exploring a way to efficiently decompress quantum correlations beyond entanglement and show how these techniques will allow the realization of information processing tasks between two previously uncorrelated nonlocal parties in the vicinity of another nonlocal correlated pair. Thus, our work highlights o

Abstract

The rapid proliferation of technology has resulted in numerous new devices, which are accessible to end users. This challenges users to quickly become familiar with any new device that they encounter. While the user learns to use a new device, her understanding of it evolves gradually. We use the term user model to refer to a finite state machine (FSM) representing the user’s understanding of a machine.In contrast to the user model, we use the term target model to refer to the FSM representing the behavior of the machine, which the end user is trying to learn. In order to learn how to operate a machine correctly, there is a line of thought within Human Computer Interaction (HCI) that the user interface must communicate the underlying target model to the user in such a way that the user’s understanding of the machine is behaviorally indistinguishable from the target model. The user may attain such a model if her multiple user models progressively approach the target model, while interacting with the device. Relatively little attention has been paid to how user models evolve as a part of a user’s learning process, which is the focus of this thesis. In this thesis, we build on the past work on FSMs for representing mental models, and propose a metric for comparing the differences between FSMs. We apply this metric to represent the process of how a user learns to use a new device by tracing the evolution of user models towards a target model. We study user learning through a progressive comparison of the user model and target model over time by using bisimulation. (Bi)simulation relations allow behavioral comparisons between two models; they indicate whether the two models are behaviorally equivalent, or not. However during learning, user models may be incomplete, erroneous and contradictory, making it important to quantify the amount of learning. This translates to the problem of determining the proximity between the two models. (Bi)simulation relations by themselves do not provide such a metric to measure proximity as they only capture the notion of order, not measure. To quantify the gap between a user model and a target model, we introduce edit distance for measuring behavioral proximity between them. We propose an algorithm to compute edit distance between two models and employ the heuristic procedure on experimental data for computing edit distance between target and user models. The data is organised into two experiments depending on the device the user interacted with: (a) a simple string generator device and (b) a close to real-world vehicle transmission model. The results indicate that the edit distance modulo bisimulation measure of a user model and user learning as measured extensionally through participant responses to given tasks have a strong downhill linear relationship (correlation co- efficient = -0.76). This validates the proposed metric as edit distance converges with progressive user learning, increases for erroneous learning, and remains unchanged indicating no learning. Thus, the work demonstrates that user learning can be witnessed, captured, and measured formally, allowing for a better understanding of how users learn to use an unfamiliar device. The proposed representational technique provides an intensional description of the process involved in learning a new device. The experimental studies indicated that our proposed edit distance metric allows us to examine several questions of interest to the HCI community about the learning process. For example, deciding if the two user models are behaviorally close, or do successive user models for all users converge at some instance, etc. The key here is not to show a mere convergence of the user models, but to capture and represent the process of their evolution to show that the convergence (or divergence) follows a user’s ability to learn the system. Such a representation allows designers to identify the problem areas in a user interface by differentiating instances when a user model is improving from instances where it is not.

Abstract

Recent advances in computer hardware and signal processing have made possible the use of EEG signals or ―brain waves for communication between humans and computers. Locked-in patients have now a way to communicate with the outside world, but even with the last modern techniques, such systems still suffer communication rates on the order of 2-3 tasks/minute. In addition, existing systems are not likely to be designed with flexibility in mind, leading to slow systems that are difficult to improve. A brain-computer interface (BCI) is a system that provides an alternate non muscular communication/control channel for individuals with severe neuromuscular disabilities. With proper training, individuals can learn to modulate the amplitude of specific electroencephalographic (EEG) components (e.g., the 8–12 Hz μ rhythm and 18-26 Hz β rhythm) over the sensorimotor cortex and use them to control a cursor on a computer screen. Conventional spectral techniques for monitoring the continuous amplitude fluctuations fail to capture essential amplitude/phase relationships of the μ and β rhythms in a compact Fashion and, therefore, are suboptimal. By extracting the characteristic rhythm for a user, the exact morphology can be characterized and exploited as a matched filter. A simple, parameterized model for the characteristic rhythm is proposed and its effectiveness as a matched filter is examined offline for a one- dimensional cursor control. Although the main objective of this research idea is to build an assistive device for ALS patients, rather than working with ALS patients directly the work done here limits itself to running experiments on healthy subjects and building a template based on one these test subjects and comparing the template with other subjects.

Abstract

The primary mRNAs or the pre-mRNAs frequently undergo splicing that involves excision of intron sequences and ligation of the coding exon sequences. Across tissues and conditions, within an individual plant and animal, the splicing can occur in more than one way for a pre- mRNA giving rise to alternative mRNA transcripts (isoforms/splice forms). It is known that such alternative splicing is the major mechanism of producing the diversity across the transcriptomes and/or proteomes of tissues using the same genome (Nilsen and Graveley, 2010). Specific short sequences of nucleotides forming the splice sites and regulatory motifs are located in the introns and exons and such 'motifs' can be used to select or de-select a specific type of intron-excision and exon-ligation. Thus, the motifs can act as enhancers or silencers of splicing. A number of studies revealed that pre-mRNA sequences also harbor structurally identifiable elements in vivo that may regulate splicing. Using such motifs and structural features, the cells seem to splice the pre-mRNAs in multiple ways. Various splice-events seem to have evolved to increase the protein repertoire of the cell. Conventional types of alternative splicing mechanisms are exon skipping, alternative 3‘and 5‘ splice sites, intron retention, mutually exclusive exons, alternative promoters and alternative poly adenylation (A) sites. While many studies have indicated the relative frequency of different types of splice events, more specific studies are warranted, specifically to study their frequency across differently expressed tissues in mammals, even under normal conditions. The analysis of motifs in the context of different type of splice events is particularly at a very preliminary stage for every species/group. Hence, the current study attempts to exploit recently established sets of tissue-specific and ubiquitously transcribed genes to compare the types of alternative splicing-events, and then explore the possible sequence and structural features across the major types of events. The presence of these RNA secondary structures is usually predicted in silico by computational programs like Mfold, RNAfold, RNAStructure, Sfold, etc and are confirmed by in vitro (by biochemical methods) and in vivo (by small scale experiments and mutational analysis) studies. Though very little is understood regarding their role in alternative splicing, the studies indicate that pre-mRNAs, being highly flexible in nature forms secondary structures (e.g. stem loop structures), whichare likely to play role in inclusion/exclusion of a particular exon(s), or in selection of 5‘ splice sites or 3‘ splice sites (donor or acceptor) and thus determine the variety of transcript-isoforms. In our attempt to understand structures of pre- mRNAs that play a role in alternative splicing events of human, mouse and rat species, we have extracted published information on 30 mammalian genes for which pre-mRNA secondary structural analysis was done either in silico or in vitro or in vivo. Exon skipping events involving cassette exons are the predominant type of alternative splicing (Ast, 2004). Earlier studies showed that 74% alternative splicing events are tissue specific (Wanget al, 2008). However, evaluating the distribution of tissue specific/cell type/developmental stage specific splice-events has not been easy for researchers despite the huge amount of genome- & transcriptome-wide experimental data. With the aim to understand tissue specific splice-events, a comparative analysis was performed in the current study on alternative splice events of 200 genes belonging to testis exclusive and ubiquitously expressed sets, obtained from MGEx-Tdb (Acharya et al, 2010). This analysis showed that apart from exon skipping, alternative promoter driven splice events are enriched in the testis exclusive genes. Alternative 5‘ and 3‘ splice sites comprise moderately abundant splice-events. Thus the results indicate that at genes expressed preferentially in different tissues show varied frequencies of splice-events and thereby generate the protein diversity. Our data also reveals that intra-exon deletions, along with intron retention, mutually exclusive events and alternative poly adenylation (A) sites, also form the minor splice-events across the tissues. With the aim to identify splice-event specific motifs, sequence analysis was performed. A distinct set of 3‘ ends of introns of cassette exons and constitutive exons were used for this purpose. Occurrence and distribution of experimentally proven human branch point motifs were analyzed across the intron-exon junctions. Though there is no significant difference in the arrangement of branch point motifs, the study discovered a few novel motifs found within 100 nucleotide length intron-exon junctions of cassette and constitutive exons. A specific novel motif of 19 bases length is particularly interesting as it i

Abstract

Due to the recent advances in the networking capabilities, individual users and organizations are willing to use online services to store and process their data. Many image searching applications use external servers to store their huge image data for providing online services such as image searching. But images being sensitive data, we need to ensure that the privacy of the database and all communicating parties are kept intact. Firstly we need to ensure the database’s security with respect to the server. Secondly, no meaningful information about the end user’s query is to be revealed to the server. Simultaneously, the server should not reveal any information other than the query results to the user. Classical Oblivious transfer protocols are capable of ensuring both the user and the server privacy as well in such cases. They allow a sender to transfer one of potentially many pieces of information to a receiver, but remains oblivious as to what piece has been transferred. But, these protocols are practically usable only if the amount of information being queried is of small size. However, for image transfer, in their original form, an oblivious transfer protocol is highly inefficient due to its huge communication overhead. In this scenario, we consider the novel problem of oblivious retrieval of similar images from an outsourced database server. We employ SIFT descriptors to process the image data. We compute the similarity between two images based on a threshold set on the distance between the obtained features. To conduct such computations, the server must usually know the inputs from the user. However, when there is no trust on the server, privacy will be a major concern for the user. This problem is referred to as secure multiparty computation(SMC) in literature. We have developed three secure distance protocols, using the concepts of SMC, with varied efficiencies based on the privacy requirements they meet. In the first and second protocols, we achieved a constant computational complexity of O(k) in terms of homomorphic operations and a linear communication complexity of O((M + N)k). In the third protocol, we achieved a constant computational complexity of O(k + m) whereas a communication complexity of O((M + N)(k + m) + MN) is achieved. The extra overhead involved in this protocol however is due to the additional privacy requirements it offers. Traditional encryption algorithms such as data encryption standard, have the weakness of low-level efficiency while encrypting large data such as images. So, to ensure security of the data on the server effectively, we use a light weight non-linear chaotic algorithm to store the images in encrypted format. They have the advantages of high-level security and large key space while maintaining acceptable efficiency. Based on these concepts, we have designed a working prototype and tested the protocol on a database of 9000 real-life images. We employed the techniques of Paillier encryption schemes in our secure distance protocols. In our protocol, the overall computation takes three rounds of communication between the client and the server. Our results show a reasonable trade-off on the image query time, when compared to the privacy requirements being satisfied.

Abstract

Ability to autonomously navigate from a start to a given goal configuration while satisfying certain requirements or constraints is at the kernel of almost every robotic applications. Whether it’s a repetitive pick and place operation in the confines of industry assembly lines or a car driving by itself in urban or off-road scenario, robotic systems are required to have the ability to autonomously plan its motions and consequently the inputs to its actuators. Such functionality in robotic systems require software or a set of algorithms which dictates the motion of the robot’s actuators depending on its perception of the environment and its location in the environment. Motion planning in robotics is the problem of developing such software or set of algorithms and is considered to be one of the fundamental problems in robotics research The proposed thesis deals with motion planning problem with differential inequality and equality constraints. The evolution model of the wheeled mobile robots are usually described as differential equality constraints. Whereas higher level requirements are modelled as differential inequality constraints. For example stability requirements for a wheeled mobile robot operating on uneven terrains can be represented as set of differential inequalities. Similarly the collision avoidance requirements for a robot operating in dynamic environments are also modelled as differential inequality constraints. In this thesis we propose computationally efficient methodologies for computing the solution space of differential constraints. We show that we are able to obtain a characterization of solution spaces by just solving a set of low dimensional linear and quadratic inequalities. Consequently we build on top of this result and propose incremental sampling based planners as well as trajectory optimization approaches for motion planning. At the secondary level, we also make contributions to some specific aspects of motion planning on uneven terrain and in dynamic environments. For example existing works on uneven terrain navigation are based on planar or point mass evolution model of the robot. In the current thesis we present the methodology to deduce the 3D evolution of the robot on uneven terrain. We also present a novel concept called Feasible Acceleration Count which acts as an unified metric for quantifying the stability of the robot on uneven terrain as well as the efficiency of the incremental sampling based planners on producing stable trajectories on uneven terrain. We also present a novel concept called time scaled collision cone which is path constrained version of the collision cone concept used to characterize the set of collision avoidance manoeuvres in dynamic environments. We show that time scaled collision cone constrains can be solved in closed form and forms the crux of the proposed motion planning framework for dynamic environments.

Abstract

Structural complexity theory deals with the study of complexity classes, their internal structure and the relationships which exist among the classes. The class P^{SAT} is the class of all languages which can be decided by a deterministic polynomial time Turing machine with oracle access to SAT oracle. By limiting the number of available queries as a resource, we can consider subsets of P^{SAT}. Here, P^{SAT[f(n)]} is the class of all languages which can be decided by a deterministic polynomial time Turing machine with oracle access to f(n) queries to SAT oracle. If the queries are asked in parallel, the class is called P^{SATp[f(n)]}. While the question of whether non-determinism brings any advantage to a deterministic polynomial time Turing machine is the famous P vs NP question, another interesting question one can ask is whether any problem which can be decided with oracle access to two queries to an NP oracle can be decided by one query to an NP oracle. Since SAT is NP-complete, the question is framed as P^{SAT[1]} vs P^{SAT[2]}. The polynomial hierarchy (PH) is one of the most well-known structures in structural complexity theory and it contains the classes P, NP, coNP as well as generalizations of these classes at different levels. The polynomial hierarchy is conjectured to have infinite levels. On the contrary, if the polynomial hierarchy happens to top out at a particular level, then it is no longer infinite and is said to collapse to that particular level. The class P^{SAT} is one of the classes that lie between the first and second levels of the polynomial hierarchy and so do the classes P^{SAT[1]} and P^{SAT[2]}. One way to think about the P^{SAT[1]} vs P^{SAT[2]} question is to look at the implications which arise while assuming that both the classes are equal. The assumption that one query to a SAT oracle is as powerful as two queries to a SAT oracle is referred to as the 'two queries assumption'. There are many implications of the two queries assumption, P^{SAT[1]}=P^{SAT[2]}, and the topic is a well-researched area. This most profound implication of the two queries assumption is the collapse of the polynomial hierarchy with several efforts bringing down the collapse to subsequently lower levels. We explore the implications of the two queries assumption, P^{SAT[1]}=P^{SATp[2]}, with respect to the polynomial hierarchy (PH) and Arthur-Merlin classes (AM and MA). We prove the following results under the assumption P^{SAT[1]}=P^{SATp[2]}: 1) AM = MA 2) There exists no relativizable proof for PH is a subset of AM 3) Every problem in PH can be solved by a non-uniform version of a Arthur-Merlin(AM) protocol where Arthur(the verifier) has access to one bit of advice. 4) PH = P^{SAT[1]MA[1]} and PH = P^{SAT[2],pr(MA Intersection coMA)[1]}) ( Here 'pr' refers to a promise version of the class) The first results shows the equivalence of the classes MA and AM under the two queries assumption. Under the two queries assumption, Chakaravarthy and Roy showed that PH collapses to their newly defined class NO_2^P Intersection YO_2^P. The second results shows the impossibility of a relativizable proof for PH being a subset of AM which we show by means of a relativized world where coNP is not a subset of MA but the two queries assumption holds. Since NP is a subset of MA which in turn is a subset of NO_2^P unconditionally, this result shows the impossibility of a relativizable collapse to MA=AM. This result also improves upon the result by Buhrman and Fortnow that we cannot show that PH is a subset of NP under the two queries assumption using relativizable proof techniques. Though a relativizable proof showing that PH is a subset of AM is not possible, we show a containment of PH in a non-uniform variant of AM where the verifier has access to one bit of advice. This relativizable result is our third result. Our fourth result shows that any problem in PH can be simulated by a deterministic polynomial-time Turing machine with one query to an NP oracle and one query to an MA oracle. This can also be done by a deterministic polynomial-time Turing machine with two queries to an NP oracle and one query to a pr(MA Intersection coMA) oracle. These two results imply that simulating MA in a P^{SAT[1]} machine is as hard as collapsing PH to P^{SAT[1]}, if the two queries assumption is assumed to be true. These two results are incomparable to the other best known results on the collapse of the polynomial hierarchy under the two queries assumption to NO_2_P Intersection YO_2_P and ZPP^{SAT[1]}.