Much work has been done on design of efficient coded modulation schemes since the publication of [Ungerboeck, 1982] for trellis coded modulation and [Imai & Hirakawa, 1977] for block coded modulation. Recently, increasing interest in digital mobile radio and indoor wireless systems has led to the consideration of coded modulation designs for combating fading channels. In this research, it is intended to present results of an investigation of the construction of Reed Solomon coded MPSK modulation which is robust for the Gaussian channel and a Rayleigh fading channel. Two approaches have been applied to Reed Solomon coded modulation. First, a Reed Solomon code was combined with MPSK signal set using Gray code mapping; this was called Reed Solomon coded modulation not based on set partitioning. This approach was the baseline scheme which would be compared with the proposed approach, namely Reed Solomon coded modulation based on set partitioning. The second approach to coded MPSK with M = 2m was multilevel Reed Solomon coding. In this case, each of the m bits defining an MPSK symbol was coded and decoded by different Reed Solomon codecs. The set partitioning principle was applied to define subsets with distances Deltai,-, (i = 1 to m) that were nondecreasing with i. Each of the m bits defined a subset and was decoded in multistage decoding schemes. The novel idea here was that in the receiver, we used a rotated 2m+1-PSK detector if the transmitter used a 2m-PSK modulator. The designs of Reed Solomon coded modulation schemes for the Gaussian channel and a Rayleigh fading channel (i.e. choice of the code configurations which were suitable for this channel) have been studied. The performance of Reed Solomon coded modulation based on set partitioning was compared with Reed Solomon coded modulation not based on set-partitioning, then with multilevel Reed Solomon coded modulation using Gray mapping and finally with coded modulation schemes using binary codes, Reed Muller codes. It has been shown that over the Gaussian channel and a Rayleigh fading channel, Reed Solomon coded modulation based on set partitioning is better than several alternatives, such as schemes not based on set partitioning, multistage Reed Solomon coded modulation based on Gray mapping and Reed Muller coded modulation. It was found that good codes for a Rayleigh fading channel have configurations in which all component codes have the same minimum Hamming distance because the fading phase is uniformly distributed random process. Therefore, by matching configurations of component codes with the channel characteristics, it was shown that Reed Solomon coded modulation based on set partitioning was robust for the Gaussian and a Rayleigh fading channel. Reed Solomon coded modulation schemes were applied to Orthogonal Frequency Division Multiplexing (OFDM) transmissions. The main disadvantage of OFDM systems is that they have high Peak-to-Mean Envelope Power Ratio (PMEPR). A scheme for reducing the PMEPR of OFDM systems was investigated. Multiphase complementary code pairs of length 2 are proposed to reduce the PMEPR of MPSK and QAM OFDM. Concatenated codes with Reed Solomon coded modulation as an inner code and an RS(511, 443) code as an outer code are proposed as coding schemes for OFDM systems.

This thesis is focused on a study on modeling and measurement of the indoor radio and infrared channels. Both channels have been studied, compared and their vital differences identified. Initially, an infrared channel model was developed that was not similar to any existing models for the infrared domain. The wireless diffuse infrared channel is solely used indoors and is usually confined within a room. Conventional channel models are described, but their disadvantage is heavy time and processor requirements. A new model is introduced, in which the approach is different from the traditional methods in the way that it discretises the delay range instead of the physical characteristics of the environment. The new model offers accurate results without the increased time and processor requirements compared with traditional techniques. Following the characterisation of the infrared channel, a wideband radio propagation campaign took place in two different buildings that allowed valuable insight into the mobile radio channel. Time domain analysis of the measurement results allowed the careful study of the radio channel and produced interesting results as far as RMS delay spread and Power Delay Statistics are concerned. It has been shown that the RMS delay spread is not always dependent on antenna separation, while it was found to be highly dependent on the clutter present on the measurement environment. The infrared model was finally converted to account for radio propagation. Traditional channel models for indoor propagation prediction are described, while the major differences of the infrared and radio channel are mentioned. The radio channel prediction benefits from the accuracy of the infrared model, where a very high accuracy is necessary in order to predict the effect of scattering. A simple measurement campaign has been introduced in order to validate the results of the simulation tool and a comparison with the most important wideband channel models has been performed, along with higher frequency measurements where scattering is more important. The results present a good fit to the measurements and models in the literature, and empirical conclusions relative to the scattering characteristics of the radio channel are drawn from these comparisons.

Abstract Photoreceptors convert the energy of light into an electric signal to be processed by the visual system. Photoreceptors of nocturnal insects are adapted for night vision by sacrificing spatial and temporal resolution for improved sensitivity. While the sensitivity-increasing optical adaptations and the temporal properties of light responses have been studied earlier, the intermediate biophysical mechanisms responsible for shaping the captured light into voltage responses were previously not known in detail in any nocturnal species. Using electrophysiological tools and computer simulations the photoreceptors of the nocturnal cockroach (Periplaneta americana) were studied by characterising 1) the electrical properties responsible for shaping the light responses, 2) the properties of light responses at different stages of light and dark adaptation and 3) properties of low-intensity light stimuli and how they are processed by the photoreceptors. The high input resistance and whole-cell capacitance were typical for a nocturnal insect, but the two voltage-dependent potassium conductances were closer to those found in diurnal species. The dominant sustained conductance typically associated with day-light vision activated during simulated light responses whereas the lesser transient conductance previously linked to low-light vision did not. Light responses were persistently slow regardless of the adapting light level and saturated at low intensities, indicating a strong adaptation to vision in dim light. Simulations showed that at such low light levels the physical noise caused by random photons determines the information rate and the biological noise, caused by random latency and amplitude of single photon responses, has only a minor effect. At higher intensities the latency variability degraded the information rates but the amplitude variability did not. Thus, photoreceptors of nocturnal animals can sacrifice phototransduction precision in their natural illumination without compromising their coding performance.

No description available.

Background: Pulmonary arterial hypertension (PAH) is a condition with severe morbidity and mortality. It is associated with an increase in incidence of all forms of arrhythmias which further increase morbidity and mortality. The monocrotaline (MCT) model of pulmonary hypertension (PH) in the rat is analogous to PAH in humans and was used to study how PH causes arrhythmias. Methods: A single injection of MCT or a volume matched saline injection (control) was given to the rats on day 0 of the protocol. The hearts of both groups of rats were studied in vivo with echocardiography (echo) and electrocardiogram (ECG). The rat’s condition was monitored and they were electively sacrificed when they showed symptoms or on day 28. Live cardiac tissue was studied using the Langendorff preparation and a right atrial preparation that incorporated the sinoatrial (SA) and atrioventricular (AV) nodes. Molecular biology techniques including reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry were used identify changes in the heart caused by PH. The effects of macitentan, an endothelin receptor antagonist used in the treatment of PAH, on the MCT injected rats was assessed using echo and ECGResults: Echo demonstrated that the MCT treated rats developed severe pulmonary hypertension with a decreased pulmonary artery acceleration time (P<0.005) and an increased pulmonary artery deceleration (P<0.005). The MCT treated rats also developed right ventricular hypertrophy (P<0.05) and dilation (P<0.005). The in vivo ECG demonstrated QT prolongation (P<0.005). Ex vivo functional experiments demonstrated QT prolongation (P<0.005) and prolonged ventricular effective refractory period (P<0.005). AV node dysfunction was also seen in the ex vivo experiments with an increased AV effective refractory period (P<0.05), AV functional refractory period (P<0.05) and incidence of complete heart block (P<0.05). RT-qPCR demonstrated significant changes in the mRNA expression of several ion channels and exchanges, Ca2+ handling proteins and autonomic receptors including a downregulation of HCN4 and CaV1.2 in the AV nodal tissues (P<0.05). Treatment of established pulmonary hypertension led to a reduction in the prolongation of the QT interval caused by MCT administration at day 21 (P<0.05).Conclusions: PH causes arrhythmogenic changes including prolonged repolarisation in the working myocardium and AV node dysfunction. These changes may be caused by dysregulation of ion channels and Ca2+ handling proteins. These ion channels and Ca2+handling proteins may play a key role in both physiological and pathological processes within the AV node.

No description available.

The availability of feedback from the receiver to the transmitter in a communication system can play a significant role. In this dissertation, our focus is specifically on binary or one-bit feedback. First, we study the problem of successive beam alignment for millimeter-wave channels where the receiver sends back only one-bit of information per beam sounding. The sparse nature of the channel allows us to interpret channel sounding as a form of questioning. By posing the alignment problem as a questioning strategy, we describe adaptive (closed-loop) and non-adaptive (open-loop) channel sounding techniques which are robust to erroneous feedback signals caused by noisy quantization. In the second part, we tightly characterize the capacity for two binary stochastic-adversarial mixed noise channels. Specifically, the transmitter (Alice) intends to convey a message to the receiver (Bob) over a binary symmetric channel (BSC) or a binary erasure channel (BEC) in the presence of an adversary (Calvin) who injects additional noise at the channel's input subject to a budget constraint. Calvin is online or causal in that at any point during the transmission, he can infer the bits being sent by Alice and those being received by Bob via a feedback link. Finally in the third part, we study the applicability of binary feedback for encoding and propose the framework of linearly adapting block feedback codes. We also prove a new result for Reed-Muller (RM) codes to demonstrate how an uncoded system can mimic a RM code under this framework, against remarkably large feedback delays.

Cloud computing usage is increasing and a common concern is the privacy and security of the data and computation. Third party cloud environments are not considered fit for processing private information because the data will be revealed to the cloud provider. However, Trusted Execution Environments (TEEs), such as Intel SGX, provide a way for applications to run privately and securely on untrusted platforms. Nonetheless, using a TEE by itself for stream processing systems is not sufficient since network communication patterns may leak properties of the data under processing. This work addresses leaky topology structures and suggests mitigation techniques for each of these. We create specific metrics to evaluate leaks occurring from the network patterns; the metrics measure information leaked when the stream processing system is running. We consider routing techniques for inter-stage communication in a streaming application to mitigate this data leakage. We consider a dynamic policy to change the mitigation technique depending on how much information is currently leaking. Additionally, we consider techniques to hide irregularities resulting from a filtering stage in a topology. We also consider leakages resulting from applications containing cycles. For each of the techniques, we explore their effectiveness in terms of the advantage they provide in overcoming the network leakage. The techniques are tested partly using simulations and some were implemented in a prototype SGX-based stream processing system.

Multiple-input and multiple-output (MIMO) technology with antenna arrays is a vital solution to achieve the advertised features in the next generation wireless communication. Multiple antennas at the transmitter and receiver can achieve diversity as well as multiplexing gain during data transmission. In order to take advantage of the multiplexing gain of MIMO systems, two or more channel paths are required to send multiple signal streams simultaneously. Beamforming (BF) training using low resolution and high resolution array beams is already implemented in the IEEE 802.11ad standard, making hierarchical codebook design an attractive approach. In this thesis, our goal is to improve multi-path channel estimation and data transmission through BF training using hierarchical codebook design. Kaiser Window sector array design and restricted orthogonal projection are applied during the beam training phase. The pre-defined hybrid-implemented codewords selected after the BF training are used for data transmission directly. With these combined efforts, a 30\% higher spectral efficiency compared to the reference design [1] is achieved. / Graduate

Stock assessment and behavioral studies are needed to identify habitat use and population dynamics of endangered pallid sturgeon Scahphirhynchus albus in the freelowing lower Mississippi River; however, effective sampling methods have not been evaluated. Trotlines and otter trawls were consequently fished year-round to determine the more effective gear and to determine effects of environmental variables on catch rates. Trotlines were more effective for catching large (> 600 mm FL) pallid sturgeon and neither gear was effective for catching small (100-600 mm FL) pallid sturgeon. Greater predicted probabilities of catching large pallid sturgeon with trotlines were in 9-19 °C water temperatures, 0.7-0.9 m s-1 surface current velocities, and in greater depths (up to 12 m). Results of this study provide information that can be used to maximize sampling efficiency.