Background: Delirium superimposed on dementia (DSD) is a highly prevalent, yet difficult to recognize problem in hospitals. Delirium is a disturbance in cognition often seen in persons aged 65 and older. DSD occurs when a person living with dementia (PLWD) also develops delirium. DSD is a highly distressing experience for caregivers. Aims: This study aims to explore the experiences of caregivers of older persons with DSD in acute care hospitals; their role in the detection and management of DSD; and the type of support they require during this experience. The knowledge generated from this study can be used to identify strategies to assist caregivers during their experience, and to improve the early detection and management of DSD, with the aim to improve health outcomes for both the hospitalized older person with DSD and the caregiver. Methods: Thorne’s interpretive description method was used. In-person, semi-structured interviews were conducted with nine caregivers of older persons with DSD who were hospitalized in four medicine units. Interviews were transcribed and thematic analysis was conducted. Results: The following themes related to caregivers’ experiences were identified: (a) caregivers found DSD to be an overwhelming experience, (b) caregivers were concerned about the quality of care that the older person received, (c) caregivers’ experiences were influenced by the nature of their relationship with the health care team, and (d) caregivers can play an important role in the detection and management of DSD. Conclusion: Findings provide guidance in increasing support and building collaborative relationships between caregivers and the health care team. Recommendations on delivering caregiver-centred care to caregivers of older persons with DSD are outlined. / Thesis / Master of Science in Nursing (MSN)

This study investigates a phenomenon that I have termed occlusion inhibition. This research and a small number of earlier studies suggest that, in some experimental conditions, when an attended (target) object is partially occluded by a distractor object, there is less attention allocated to the occluded region of the target object than to the visible parts of that object. In the literature, there are mixed results concerning this attentional effect. Some studies find it and others do not. This study investigates the differences between those conflicting studies with the goal of identifying the factor or factors that govern when occlusion inhibition occurs. Evidence is presented to rule out a number of potentially relevant factors such as depth perception, figural complexity, set size, the use of real world vs. abstract geometric objects, the position of occlusion, the number of overlaps in the display, and the adoption of the attend-object paradigm over the spatial cueing paradigm. After all these factors are ruled out, Experiments 3 and 4 provide evidence for a factor that does determine whether occlusion inhibition occurs or not. These two experiments differ only in the fact that participants are required to report the border color of the target object in Experiment 3 and not in Experiment 4. This task was designed to ensure that participants fully attend to the target object. Occlusion inhibition occurs when the target color is reported, but not when no target color report is required. Removing the target reporting task was found to be an effective means of turning occlusion inhibition on and off. The results of these experiments suggest that, if occlusion inhibition is to take place, attentional selection of overlapping figures requires the target object to be fully processed. This conclusion in turn suggests that attention does not automatically exclude the irrelevant portions of occluded objects, but that attention selects the entire location of the object and then, through reiterative feedback mechanisms, fine tunes the information to inhibit areas that do not belong to the object.

Bandwidth efficiency is a critical concern in wireless communications. To fully utilize the available bandwidth, the superimposed training (ST) scheme is adopted in this thesis for orthogonal frequency division multiplexing (OFDM) systems without using the cyclic prefix (CP) and the guard interval (GI). It is shown that the performance of the channel estimation using the ST scheme is the same for both the proposed architecture, denoted as OFDM-ST, and the conventional OFDM system with CP, denoted as CP-OFDM-ST. In addition, since the CP is not added in the proposed system, leading to substantial increase in both the inter-symbol interference (ISI) and the inter-carrier interference (ICI), an interference cancellation scheme is derived. To further improve the performance of channel estimation using ST scheme, the joint ML data detection and channel estimation method is investigated. The simulation results illustrate that the proposed algorithm enhances the systems performance significantly. Finally, it is demonstrated that the proposed structure has a much better effective data rate than the CP-OFDM-ST system.

The continuous phase modulation (CPM) has a constant envelope and compact output power spectrum that makes it a promising underlying technology for power and spectrum efficient broadband wireless communications. However, high implementation complexity (especially the complexity of the receiver) required to deal with the phase memory and inter-symbol interference has impeded its adoption for broadband wireless communications, and only a few simple CPM modulation schemes have mainly been used, e.g. binary MSK and GMSK. Thus, research on efficient CPM transceivers to reduce the computational and hardware complexity is important. The major contribution of this dissertation is the development of novel frequency domain processing techniques and transceiver strategies to improve power and spectral efficiency, and reduce the complexity of CPM modulation schemes. First, this dissertation presents simplified frequency domain receiver structures and decoding schemes in the frequency domain for binary and M-ary CPM block transmission. The frequency domain receivers utilize parallel and serial structures with frequency domain processing which considerably reduces hardware and computational complexity compared to conventional time-domain processing. In addition, the decoding schemes in the frequency domain eliminate the controlled phase memory through frequency domain phase equalization instead of maximum-likelihood sequential decoders, e.g. Viterbi decoders. Second, frequency domain channel estimation schemes for CPM block transmission are presented, which adopt superimposed training signals to achieve bandwidth and power efficiency while reducing the complexity. In these schemes, the proposed frequency domain channel estimation uses the superimposed training signals as a reference signal to reduce the throughput loss caused by conventionally multiplexed training signals. Superimposed training signal design is presented, and the trade-off between bandwidth efficiency and power efficiency is also analyzed. Third, block transmission schemes and frequency domain equalization methods for CPM are proposed, which consider linear processing instead of conventional decomposition-based processing. The schemes of frequency domain linear processing avoid the complexity overhead (both in computation and hardware) of conventional orthogonal- or Laurent decomposed-based equalizers. Finally, this dissertation extends CPM block transmission and frequency domain equalization to phase-coded (time-varying modulation index) CPM, which shows better error performance and bandwidth efficiency than fixed modulation index CPM's. / text

Abstract In time delay estimation the correlator or, equivalently, matched filter estimator is widely used. Examples of its usage can be found in the global positioning system (GPS), radars and code division multiple access (CDMA) communication systems. Although widely used its performance is not studied in general case until recently. Partially this study is done in this thesis. If interfering signals like multipath or multiple access signals exist in addition to additive white Gaussian noise, as in GPS and CDMA, the correlator is not a maximum likelihood (ML) estimator. However, it is known that the correlator produces consistent estimates in the existence of multipath interference if the delay separation is larger than the correlation time of the signal (in direct sequence spread spectrum applications such as GPS and CDMA, the correlation time approximately equals the chip duration of the spreading code). It also performs well in the existence of multiple access interference (MAI), if the powers of the MAI signals are equal to the power of the desired signal. In this thesis the asymptotic distribution of the correlator estimator is derived in multisignal environments. Using the result, it can be analytically shown, that in these benign interference cases the exact ML estimator and the correlator estimators perform equally well in the sense that their asymptotic covariance matrices are equal. The thesis also verifies the well known result that if the signals are orthogonal, then the correlator and ML estimators perform equally. In addition, the correlator's asymptotic performance is investigated also in the inconsistent case by slightly extending the earlier results found in the literature. Also the resolution of the correlator estimator is investigated. It is numerically shown that the correlator estimator can produce consistent estimators even if the delay separation is less that the chip duration, which is commonly believed to be the resolution limit of the correlator. This can happen in fading channels where the multipath amplitudes are uncorrelated or just slightly correlated. This result seems to be fairly unknown. In addition to the classical ML estimator, where all the unknowns are assumed to be deterministic, also an improved ML estimator is investigated. This other ML estimator is obtained by assuming that the amplitudes are Gaussian distributed. It is an improved estimator in the sense that its asymptotic covariance, say CML, is less positive definite than that of the classical ML estimator CCML, i.e., CCML-CML is positive semidefinite. More importantly, this result is valid independent of the fact are the amplitudes really deterministic or Gaussian. This well known result is shown in this thesis to be valid also if the signals contain more than one unknown parameter, which occurs, for example, in direction-of-arrival estimation when two angles per arrival are to be estimated.

No description available.

This thesis explores methodologies of modeling and evaluating the operational performance of a typical aeroengine having field experience over two decades. Upon failure, the engine is repaired and restored to flight worthy condition and hence comes under the purview of repairable systems. Operational performance of the engine is being measured in terms of five functions of time, namely, M(t), which is the expected number of system failures in the time interval [0,t]; system failure rate m(t), which is an unconditional quantity and is simply the derivative of M(t); ρ(t), the conditional failure intensity given the history of a system Ht, which is nothing but limdt→1 Prob(System fails in [t,t + dt] |Ht); and M′(t) and m′(t), which are 0 dt conditional entities analogous to M(t) and m(t) defined in the same spirit as that of ρ(t), the details of which are given in the third chapter of the thesis. These functions are being estimated using field failure-repair data of 418 aeroengines, where the observations on time between failures are being measured in number of flying hours logged in between failures, and the corresponding repair duration is being measured in number of calendar days. To start with, using the superimposed renewal process model the above quantities M(t), m(t), m′(t), M′(t) and ρ(t) are estimated both in the frequentist as well as the Bayesian framework. Subsequently repair times have been incorporated into the model and analysed using both frequentist and Bayesian approaches. Next, the model of Lawless and Thiagarajah (1996) which incorporates both renewal and time trend, has been generalized to include repair time as well, and a comprehensive methodology of Bayesian model selection under this model has been developed. After introducing the research problem in the first chapter, the engineering system description leading to the identification of the failure modes, repair practice and the variables of interest is taken up in the following chapter at the outset, as a pre-requisite to the stochastic modeling and the statistical analysis that to follow in the remainder of the thesis. As the first stochastic model, the number of system failures in a given time interval is modeled as a superimposed renewal process with the constituent independent renewal processes running in different component sockets having Weibull inter failure times. This model is first empirically validated using the field failure data and then using this model, the five quantities of interest as mentioned above viz. M(t), m(t), ρ(t), M′(t) and m′(t) are analysed from a frequentist maximum likelihood perspective. A Bayesian analysis of the same follows in the subsequent chapter. Next, the repair effect is incorporated into the superimposed renewal process model by considering the Weibull parameters of inter failure times of the constituent renewal processes running in independent component sockets as a polynomial in the last repair time. The nature of this polynomial relationships are empirically deter-mined and the Weibull assumption is validated through a test of hypothesis. Different polynomial relationships lead to consideration of several models, with the correct ones chosen through a series of likelihood ratio tests. Next based on the appropriate models a maximum likelihood analysis of M(t), ρ(t) and M′(t) has been carried out. Like the simple superimposed renewal process model, Bayesian analysis of this model incorporating repair times is carried out in the following chapter. In the Bayesian setup however, the problem of model selection could be kept unrestricted to non-nested models as well (unlike the previous chapter, where only nested models could be considered), and a comprehensive model selection exercise has been carried out with the aid of intrinsic Bayes factors and training data sets. The last but one chapter presents a generalised model of Lawless and Thiagarajah (1996) for performance evaluation of aeroengines that incorporate renewals, time trends and the repair characteristics. Here also since the primary problem is one of model selection, the entire analysis like in the preceding chapter has been carried out under the Bayesian frame-work. The final chapter concludes the thesis by comparing the empirical results obtained in the previous five chapters, summarising the main contributions of the thesis and providing directions for future research.

In data-dependent superimposed training (DDST) system, the data sequence subtracts a data-dependent sequence before transmission. The receiver cannot correctly find the unknown term which causes an error floor at high SNR. In this thesis, we list some helpful conditions to enhance the performance for precoding design in DDST system, and analyze the major cause of data misidentification by singular value decomposition (SVD) method. Finally, we propose a precoding matrix based on [C.-P. Li and W.-C. Huang, ¡§A constructive representation for the Fourier dual of the Zadoff¡VChu sequences,¡¨ IEEE Trans. Inf. Theory, vol. 53, no. 11, pp. 4221¡Ð4224, Nov. 2007]. The precoding matrix is constructed by an inverse discrete Fourier transform (IDFT) matrix and a diagonal matrix with the elements consist of an arbitrary perfect sequence. The proposed method satisfies these conditions and simulation results show that the data identification problem is solved.

In this thesis, a 6-beam combiner using multiplexed holograms in dye-doped polymer is investigated. It is realized by recording six superimposed holographic gratings, which show uniform diffraction efficiency. The coupled wave theory for N superimposed gratings is more generalized and is used to analyze the amplitudes of diffracted waves in three different boundary conditions. Multiple-ring diffracted beam analysis is proposed to determine the dynamic range of a holographic material. The M/# is evaluated by recording a single hologram and counting the number of ring patterns in the diffracted beam. This analysis is extended to assess the equalized grating strength of N superimposed holograms. Six holograms with the equalized grating strength which can be assigned within the dynamic range of our material and show maximum diffraction efficiency are recorded. The phase locking of five beams to one reference beam is performed using PZT controller. The designs of lock-in amplifier, ramp generator and servo using commercial chips are demonstrated. The readout set-up used to split one single beam into six coherent copies is presented. The function of each part of the PZT controller in the readout set-up is discussed in detail. The intensity profile of an N-beam combiner is investigated by varying the phase angle between adjacent input waves. The entire solution which describes the amplitude of a combined beam is derived from generalized coupled wave theory. A simplified experimental set-up without a complicated PZT controller is demonstrated using a planoconvex lens. In order to provide six coherent light sources in future work, the injection locking of a single laser diode to the master laser diode is performed. An expected read-out setup is proposed to carry out both the achievement of six coherent sources and a 6 beam combination.

Les dunes de sable sont des formes très présentes en milieu marin. Comprendre l'évolution des dunes est un enjeu important pour prévoir les caractéristiques de l'écoulement, les flux sédimentaires, et les variations de la bathymétrie. Les dunes sous-marines représentent un risque pour les activités humaines, a fortiori avec l'intérêt croissant pour les énergies marines renouvelables, pour la navigation, ou l'industrie offshore. Bien que la connaissance des dunes représente un intérêt scientifique et opérationnel de premier ordre, les processus physiques conduisant leur évolution sont toujours mal compris. En outre, la prévision de leurs caractéristiques géométriques et de leur dynamique basée essentiellement sur des formules empiriques reste peu précise. Dans ce travail de thèse, un modèle numérique est d'abord utilisée pour modéliser les dunes soumises à un écoulement stationnaire. Les simulations reproduisent l'évolution d'un fond faiblement perturbé jusqu'à un champ de dunes en équilibre avec l'écoulement et apportent des connaissances approfondies sur les processus physiques mis en jeu. Ensuite, les résultats d'un ensemble de campagnes de mesures réalisées dans la passe sud du bassin d'Arcachon permettent d'étudier la dynamique des dunes tidales in situ et relier leur asymétrie et leur migration aux résiduels de transport sédimentaire. Enfin, l'application du modèle numérique avec les conditions de forçages extraites des campagnes de mesures permet de reproduire la dynamique des dunes tidales ainsi que la génération de rides d'un ordre de grandeur comparable aux rides surimposées observées in situ. Ces résultats ouvrent des perspectives intéressantes en vue du développement d'un modèle opérationnel de prévision de la dynamique des dunes tidales. / Sand dunes are ubiquitous beforms in nature within subaqueous environments. Understanding dune evolution is important issue to accurately predict the ow circulation, sediment uxes and bathymetric variations in sandy subaqueous environments. Sand dunes may pose a significant risk for offshore activities in coastal environments, especially with the growing development of renewable marine energy, for navigation or the offshore industry. Although sand dunes represent a great scientific and operational interest, their evolution is still poorly understood due to their complex behavior. The aim of the thesis work was to study the physical processes driving the evolution of subaqueous sand dunes and to understand their in situ dynamics within tidal environments. First, a numerical model was employed to simulate sand dunes under stationary current conditions. The simulations reproduced the morphodynamic evolution of a slightly perturbed bed until a steady sand dune field in equilibrium with the ow. The results offered a deeper understanding of the physical processes driving the bed evolution to equilibrium. Second, an array of in situ measurements was carried out into the Arcachon inlet, in southwest France, to study the dynamics of tidal sand dunes. For the first time their asymmetry and migration rates were linked to the sediment uxes residuals on a spring-neap tidal cycle. Finally, the numerical model was adapted both to simulate the dynamics of tidal sand dunes, and generate bedforms of the same order of magnitude as the in situ dune-superimposed ripples starting from a at bed. These results open promising perspectives for the development of a numerical tool capable of predicting the behavior of sand dunes within tidal environments.