We studied Heart Rate Variability (HRV) evolution during therapeutic hypothermia in newborns with hypoxic ischemic encephalopathy (HIE) using spectral analysis. We hypothesized that HRV measures are predictive of neurological outcome in babies with HIE. Non-stationarity in the data causes inaccurate quantification of the spectral power. A modification was proposed to power spectral analysis approach to mitigate the effect of non-stationarity. The modified and the standard approaches were applied to cardiac beat-to-beat intervals of newborns receiving hypothermia treatment. The performance of the approaches in distinguishing the RRi dynamics of two groups of newborns was assessed using area under the receiver operating characteristic (ROC) curve. Our results showed that the modified spectral analysis distinguished the two groups of neonates better than the standard approach. These results may be useful in identifying the deteriorating physiology of the infants receiving hypothermia treatment early in time and strategize alternate interventions for them.

Master of Public Health / Department of Diagnostic Medicine/Pathobiology / Deon Van der Merwe / Cyanobacteria are Gram-negative photosynthetic bacteria capable of producing toxins responsible for morbidity and mortality in humans and domestic animals. Many are capable of forming concentrated blooms that impact the environment by limiting the growth of sub-surface plants and phytoplankton. Harmful algal blooms (HABs) are also capable of producing multiple types of toxins, creating a potential hazard to recreational water users and animals drinking water from or near a bloom. Characterization of HABs is necessary to prevent these human and animal exposures and includes classifying of the type of cyanobacteria present and whether or not they are capable of toxin production, and the exact type of cyanotoxin that is actually present in bloom. Current methods used to classify cyanobacteria and cyanotoxins include microscopy, bioassays, ELISA, PCR, HPLC, and LC/MS. All of these methods, however, have limitations that include time, labor intensity, or cost. Fourier-Transform Infrared Spectroscopy (FTIR) is another potential tool for cyanobacterial classification that is not limited by these factors. To examine the practicality of this method, library screening with default software algorithms was performed on diagnostic samples received at the Kansas State University Veterinary Diagnostic Lab, followed by PCA of samples meeting minimum quality requirements to produce cluster analyses and dendrograms. Both spectrometers and software packages used were successful at distinguishing cyanobacteria from green algae in clean samples with 89.13% agreement. PCA resulted in clear classification of cyanobacteria or green algae demonstrated by a large order of magnitude difference produced by average Euclidian distance dendrograms. While this method is only capable of differentiating cyanobacteria from green algae or other aquatic environmental constituents, its simple, rapid use and low cost make it a beneficial screening tool when coupled with toxin-detection methods to characterize HABs.

Abstract A computer program has been written to simulate the conditions of the early uni- verse and to test a new idea in the mechanism of structure formation observed in our universe today. The model utilises Newtonian hydrodynamic equations includ- ing gravitational and electromagnetic forces in two spatial dimensions. It is proposed that augmenting gravitational forces with plasma forces will complement the prob- lematic Big Bang theory of structure formation which relies on gravity alone. Two sets of initial conditions are tested and the products of the simulation are analysed in a statistical way using power spectra and the two-point correlation function. Differ- ences in the initial conditions were not seen to produce significantly different results. The results show that the Hubble expansion term significantly reduces power in the gravity models but plasma forces can retain power better than similar gravitation- only models. Initial velocity perturbations significantly modify the power spectrum gradient in the higher modes. Some power spectra displayed a definite bend in gra- dient at a scale which is verified by galaxy survey observations. Plasma forces also appear to cluster matter on smaller scales more efficiently than gravity alone. Thus, this simulation lays a foundation for a more detailed and realistic model that may be compared with real matter distribution observations.

Au cours de cette thèse nous nous intéressons à des orthogonalités asymptotiques (au sens ou le produit scalaire dans le tore discret de taille N tend vers 0 lorsque N tend vers l’infini) entre certaines fonctions liées aux blocs des chiffres des entiers et la fonction de Möbius (ainsi qu’avec la fonction de von Mangoldt). Ces travaux prolongent ceux de Mauduit et Rivat et répondent partiellement à une question de Kalai posée en 2012. Au cours du Chapitre 1 nous établissons ces estimations asymptotiques dans le cas où la fonction étudiée est une fonction exponentielle d’une fonction qui compte les blocs de chiffres consécutifs ou espacés de taille k fixé dans l’écriture de n en base q. Nous donnons aussi une grande classe de polynômes agissant sur les blocs de chiffres qui nous fournissent un théorème des nombres premiers et une orthogonalité asymptotique avec la fonction de Möbius. Dans le Chapitre 2, nous obtenons un principe d’aléa de Möbius avec dans le cas où notre fonction est une fonction exponentielle d’une fonction qui compte les blocs de ‘1’ consécutifs dans l’écriture de n en base 2, où la taille du bloc est une application croissante tendant vers l’infini, mais avec une certaine restriction de croissance. Dans le cas extrémal, que nous ne pouvons pas traiter, ce problème est lié à l’estimation du nombre de nombres premiers dans la suite des nombres de Mersenne. Dans le Chapitre 3, nous donnons des estimations dans le cas où la fonction est l’exponentielle d’une fonction qui compte les blocs de k ‘1’ dans l’écriture de n en base 2 où k est grand par rapport à log N. Une conséquence du Chapitre 3 est que les résultats du Chapitre 1 sont quasi optimaux. / Throughout this thesis, we are interested in asymptotic orthogonality (in the sense that the scale product of the discrete torus of length N tends to zero as N tend to infinity) between some functions related to the blocks of digits of integers and the Möbius function (and also the von Mangoldt function). Our work extends previous results of Mauduit and Rivat, and gives a partial answer to a question posed by Kalai in 2012. Chapter 1 provides estimates in the case of the function is the exponential of a function taking values on the blocks (with and without wildcards) of length k (k fixed) in the digital expansion of n in base q. We also give a large class of polynomials acting on the digital blocks that allow to get a prime number theorem and asymptotic orthogonality with the Möbius function. In Chapter 2, we get an asymptotic formula in the case of our function is the exponential of the function which counts blocks of consecutive ‘1’s in the expansion of n in base 2, where the length of the block is an increasing function that tends (slowly) to infinity. In the extremal case, which we cannot handle, this problem is connected to estimating the number of primes in the sequences of Mersenne numbers. In Chapter 3, we provides estimates on the case of the function is the exponential of a function which count the blocks of k ‘1’s in the expansion of n in base 2 where k is large with respect to log N. A consequence of Chapter 3 is that the results of Chapter 1 are quasi-optimal.

Os modelos de covariância são ferramentas geoestatísticas essenciais para mapear a continuidade espacial. A abordagem atual busca um modelo de continuidade espacial lícito com mínima ou até mesmo sem nenhuma interferência do usuário. Alinhado a essa visão moderna, é proposto obter uma tabela de covariância que visa substituir na prática o modelo tradicional explicitamente definido de covariância. Essa tabela de covariância é obtida por meio de três etapas: interpolar o conjunto de dados para preencher um grid regular, aplicar a convolução através do algoritmo da transformada rápida de Fourier e, por fim, transformar de volta para o domínio espacial. O modelo base para extrair covariância representa o ponto chave comparando com os métodos anteriores que propuseram o uso da tabela de covariância. Os resultados são satisfatórios, tanto na validação estatística do método, quanto na rapidez de obtenção de uma análise de continuidade espacial. Um estudo de caso tridimensional ilustra a aplicação prática através de krigagem e simulação geoestatística em comparação com a modelagem espacial tradicional. / Covariance models are essential geostatistical tools to map spatial continuity. The current approach pursues a licit spatial continuity model with minimum or even no user interference. Aligned with this modern view we propose to obtain a covariance table that aims at replacing in practice traditional covariance explicit defined model. This covariance table is obtained through a three steps work flow: interpolating the dataset to fill up a regular grid, auto convolute via Fast Fourier Transform algorithm and back transform to spacial domain. The base model to extract covariance represents the turning point comparing with previous methods that proposed covariance table usage. The results are satisfactory, both in the statistical validation of the method and in the speed of obtaining a spatial continuity analysis. A three dimensional case study illustrates the practical application for kriging and geostatistical simulation in comparison with traditional spatial modeling.

Várias técnicas de cifragem óptica de imagens surgem a todo o momento devido à necessidade que se tem de transmitir informações de uma maneira segura e confiável. Nessas técnicas a informação é criptografada de tal modo que para conseguir recuperar a informação criptografada é necessário ter um conhecimento prévio da mesma chave que a criptografou, sendo esta chave única. Isto faz com que as técnicas sejam robustas. Estes processos de cifragem de imagem trabalham com a distribuição de fase obtida diretamente da imagem que se deseja criptografar e conseqüentemente a imagem decodificada também está em modulação de fase. Porém imagens em distribuição de fase não são visíveis ao olho humano. Para transformá-Ias em modulação de amplitude, a qual é visível ao olho humano, é utilizado o método de contraste de fase de Zernike. Propôs-se então um método para cifrar imagem binária apenas em modulação de amplitude. Após o processo de decodificação, a imagem obtida é reconhecida graças à capacidade do olho humano em discernir regiões contínuas de regiões aleatórias. Este método é de fácil implementação, podendo ser obtido utilizando apenas materiais de baixo custo como papéis, filmes plásticos, etc. Vários ataques foram realizados contra o processo de cifragem óptica de imagens utilizando máscara binária aleatória para analisar a robustez de tal processo. Este processo de cifragem não é robusto ao ataque do texto conhecido e ao ataque das cifras conhecidas. / Several optical encryption techniques have been developed due to the need to transmit information in a secure and reliable way. In these techniques the information is encrypted in a way that to recover the encrypted information is necessary to have a previous knowledge of the same mask that encrypted it, being this mask unique. Because of this, the techniques are robust. These image encryption methods work with the phase distribution obtained directly from the image that is intended to encrypt and consequently the decrypted image will also be in the phase modulation. But, images in a phase distribution are not visible for the human eyes. To transform them in an amplitude modulation, that is visible for the human eyes, it is used the Zernike phase contrast method. Then, it is proposed a method for encryption and decryption of information processed in a binary form in an amplitude modulation. After the decryption process, the image obtained is recognized because the human eyes are able to differentiate continuous, periodical regions to random pattern. This method has an easy implementation and it can be obtained using regular and inexpensive materials, like paper, plastic films, etc. Many attacks were realized against the proposed method to analyse if this method is robust. This method can not resist the known-plaintext attack and the known-ciphertext attack.

Este trabalho apresenta um estudo da aplicação da Transformada de Fourier Janelada à Qualidade da Energia Elétrica. Esta abordagem procura, pela implementação de um algoritmo computacional, detectar, localizar e classificar eventuais distúrbios que ocorrem em um determinado Sistema Elétrico. Da situação atual, tem-se que variações nas formas de ondas dos sinais de tensão como elevação, afundamento e interrupção de tensão, oscilações transitórias e ruídos, são freqüentes, chamando a atenção para a qualidade da energia elétrica fornecida pelas concessionárias. A análise de tais fenômenos, que normalmente é descrita no domínio do tempo (resolução de equação diferencial) ou no domínio da freqüência (através da Transformada de Fourier), pode agora ser analisada simultaneamente em ambos os domínios do tempo e da freqüência, dispondo-se da Transformada de Fourier Janelada. As janelas utilizadas para esta finalidade foram as de Hanning, retangular e a de Kaiser. Para esta análise em específico, a simulação dos diversos distúrbios ocorridos no sistema de distribuição foi realizada através do software ATP - Alternative Transients Program - cujas características seguem corretamente um sistema real da concessionária CPFL - Companhia Paulista de Força. Os testes efetuados mostraram que a Transformada de Fourier Janelada possui uma grande potencialidade quanto à sua aplicação na avaliação da qualidade da energia elétrica. / This dissertation presents a study of Windowed Fourier Transform applied to Power Quality. By the implementation of a computational algorithm, this approach aims to detect, locate and classify disturbances that may occur in Power Systems. Variations in voltage waveforms, such as sag, swell, interruption, oscillatory transient and noise have became frequent in electric systems, attracting the attention to the power quality supplied. The analysis of such phenomena, which is usually described either in the time domain (differential equation resolution) or in the frequency domain (Fourier Transform), can now be analyzed simultaneously in both domains: time and frequency, by the windowed Fourier Transform. The windows used to provide this information are the Hanning, rectangular and Kaiser. The simulation of the diverse disturbances occurred in the distribution system was accomplished by means of ATP software - Alternative Transients Program - whose characteristics correctly follow a real distribution system of CPFL electric utility. The tests show the windowed Fourier Transform has a great potentiality when applied to evaluate the power quality.

Efficient implementation of the number theoretic transform(NTT), also known as the discrete Fourier transform(DFT) over a finite field, has been studied actively for decades and found many applications in digital signal processing. In 1971 Schonhage and Strassen proposed an NTT based asymptotically fast multiplication method with the asymptotic complexity O(m log m log log m) for multiplication of $m$-bit integers or (m-1)st degree polynomials. Schonhage and Strassen's algorithm was known to be the asymptotically fastest multiplication algorithm until Furer improved upon it in 2007. However, unfortunately, both algorithms bear significant overhead due to the conversions between the time and frequency domains which makes them impractical for small operands, e.g. less than 1000 bits in length as used in many applications. With this work we investigate for the first time the practical application of the NTT, which found applications in digital signal processing, to finite field multiplication with an emphasis on elliptic curve cryptography(ECC). We present efficient parameters for practical application of NTT based finite field multiplication to ECC which requires key and operand sizes as short as 160 bits in length. With this work, for the first time, the use of NTT based finite field arithmetic is proposed for ECC and shown to be efficient. We introduce an efficient algorithm, named DFT modular multiplication, for computing Montgomery products of polynomials in the frequency domain which facilitates efficient multiplication in GF(p^m). Our algorithm performs the entire modular multiplication, including modular reduction, in the frequency domain, and thus eliminates costly back and forth conversions between the frequency and time domains. We show that, especially in computationally constrained platforms, multiplication of finite field elements may be achieved more efficiently in the frequency domain than in the time domain for operand sizes relevant to ECC. This work presents the first hardware implementation of a frequency domain multiplier suitable for ECC and the first hardware implementation of ECC in the frequency domain. We introduce a novel area/time efficient ECC processor architecture which performs all finite field arithmetic operations in the frequency domain utilizing DFT modular multiplication over a class of Optimal Extension Fields(OEF). The proposed architecture achieves extension field modular multiplication in the frequency domain with only a linear number of base field GF(p) multiplications in addition to a quadratic number of simpler operations such as addition and bitwise rotation. With its low area and high speed, the proposed architecture is well suited for ECC in small device environments such as smart cards and wireless sensor networks nodes. Finally, we propose an adaptation of the Itoh-Tsujii algorithm to the frequency domain which can achieve efficient inversion in a class of OEFs relevant to ECC. This is the first time a frequency domain finite field inversion algorithm is proposed for ECC and we believe our algorithm will be well suited for efficient constrained hardware implementations of ECC in affine coordinates.

Tissue, in particular its mechanical properties, is of interest from a material science point of view. The collagen fiber framework found in nearly all tissue forms the basis for the tissue's behavior. Connective tissue provides more interesting behavior, designed to bear significant load in one direction, while retaining the ability to stretch in other directions. Contributing factors to such behavior are fiber diameter and orientation. Small angle scattering analysis has been developed over the past century. Particular attention has been paid to x-ray and neutron scattering, both of which characterize features on a nanometer scale. Small angle light scattering (SALS) has the ability to characterize features on a micron scale, and is thus suitable for the analysis of collage fibers. Scattering data from several tendons were analyzed using the Generalized Indirect Fourier Transform (GIFT) program developed by Dr. Otto Glatter. The data is fit using cubic B-splines, and transformed into a probability density distribution function (abbreviated PDDF or p(r)). The PDDF can then be interpreted to give an average fiber diameter, as well as other structural information. Since this type of analysis has never been performed on collagen fibers, emphasis was placed on validating small angle light scattering as an appropriate technique to characterize collagen fiber diameter. This was accomplished by comparing the results with optical microscopy. Results from SALS analysis agree with features observed by optical microscopy. Small angle light scattering analysis is able to provide an analysis of structures superior to that of optical microscopy. Small angle scatter theory provides a three dimensional analysis of the structure. On the other hand, optical microscopy provides only a two dimensional view of the sample. The structure of collagen fibers in tissue is certainly three dimensional, making small angle light scattering a more suitable technique for characterization.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-11-04T14:53:35Z No. of bitstreams: 1 Helmuth Reguly Junior_.pdf: 1561804 bytes, checksum: b11f0f561f69a1560738aa1ccb8f4118 (MD5) / Made available in DSpace on 2015-11-04T14:53:35Z (GMT). No. of bitstreams: 1 Helmuth Reguly Junior_.pdf: 1561804 bytes, checksum: b11f0f561f69a1560738aa1ccb8f4118 (MD5) Previous issue date: 2015-06-24 / UNISINOS - Universidade do Vale do Rio dos Sinos / No presente trabalho, foram feitas análises espectrais de sinais de flutuação de pressão obtidos de simulações computacionais de leitos fluidizados. As simulações foram realizadas com o aplicativo ANSYS FLUENT 14.0. O modelo multifásico empregado foi o modelo de dois fluidos (TFM) Euler-granular. As tensões das fases sólidas foram modeladas pela Teoria Cinética dos Escoamentos Granulares (KTGF). Foram simulados dois leitos, um leito bidimensional em regime de fluidização rápida e um leito tridimensional em regimes borbulhante e turbulento, ambos com partículas do grupo B de Geldart. Os sinais de flutuação de pressão gerados nas simulações numéricas foram analisados via densidade espectral de potência. Foram identificados o mínimo período de tempo de simulação para gerar sinais estatisticamente significativos, bem como a mínima frequência de aquisição necessária para o tratamento dos sinais, os quais foram iguais a 32,5 s e 250 Hz, respectivamente. No leito 3D, o regime borbulhante foi caracterizado por picos nas frequências de 1,5 e 2,2 Hz, enquanto o regime de fluidização rápida simulado em 2D foi caracterizado por um pico a uma frequência de 0,12 Hz, o que se acredita estar relacionado com a frequência de movimento dos aglomerados de partículas. Também foi possível verificar a diferença entre os espectros de potência dos regimes borbulhante e turbulento, que são diferenciados pelos picos de frequência. No regime borbulhante foram identificados dois picos de frequência, enquanto no regime turbulento foi identificado apenas um pico. / In this study, spectral analyses of pressure fluctuation signals obtained from computational simulations of fluidized beds were done. The simulations were performed using ANSYS FLUENT 14.0. The multiphase model employed was the Euler-granular two-fluid model (TFM). The solid stresses were modeled by the kinetic theory of granular flows (KTGF). Two beds were simulated, a two-dimensional bed in fast fluidization regime and a three-dimensional bed in bubbling and turbulent regimes, both with Geldart-B particles. The pressure fluctuation signals generated by numerical simulations were analyzed via power spectral density. The minimum simulation periods to generate statistically significant signals were identified, as well as the minimum sampling rate required for the processing of signals, which were found equal to 325 and 250 Hz, respectively. In the 3D bed, the bubbling system was characterized by peaks at frequencies of 1.5 and 2.2 Hz, while the fast fluidization regime simulated in 2D was characterized by a peak at a frequency of 0.12 Hz, which may be related to the rate of motion of clusters. A major difference between the power spectra of bubbling and turbulent regimes was observed. In the bubbling regime, two frequency peaks may be identified, while in turbulent regime only one frequency peak appears.