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No description available.

A utilização da técnica de teleterapia para tratamento de câncer tem sido usada por anos com bons resultados clínicos. Em meados da década de 90, a remoção do filtro aplainador, item que compõe o cabeçote de um acelerador linear de uso clínico, tem sido objeto de estudos por demonstrar bons resultados no tratamento de alguns tipos de câncer. Técnicas utilizadas como Radioterapia de Intensidade Modulada (IMRT) e Radioterapia Estereotáxica (SRT), mostram-se mais eficazes quando não se utiliza o filtro aplainador. A empresa Varian Oncology lançou em 2012 um acelerador linear de uso clínico capaz de operar com o filtro aplainador (FF) e sem o filtro aplainador (FFF), o TrueBeam. Os objetivos desse trabalho são avaliar a homogeneidade de dois importantes parâmetros utilizados para o cálculo de dose nos pacientes submetidos ao tratamento com esse modelo de acelerador linear, a porcentagem de dose profunda (PDP) e índice de qualidade do feixe (TPR20/10). Os dados fornecidos para a análise foram cedidos pelo Hospital Israelita Albert Einstein (HIAE), Real Hospital Português (RHP) e 3 instituições norte-americanas. Através de uma análise estatística dos dados das instituições citadas pode-se observar melhor o comportamento desses parâmetro que demonstraram-se muito homogêneos e com erros menores que 1% na maioria dos casos, confirmando desse modo que os aceleradores lineares do modelo TrueBeam mantém na maioria das vezes uma boa concordância dos parâmetros analisados. / Teletherapy, radiation therapy with linear accelerators, for cancer treatment has being used for years with good clinical results.Since the 90\'s the removal of the flattening filter, item placed at the gantry of the machine, has shown better results for the treatment of some cancers thus being extensively studied. Treatments with Intensity Modulated RadioTherapy (IMRT) and Sthereotaxic RadioTherapy (SRT) were more efficient without the flattening filter. Varian Oncology released the TrueBeam in 2012, a accelerator capable of operating with or without the flattening filter. The aim of this work is to access homogeneity of the percentage depth dose (PDP) and beam quality index (TPR20/10), two important parameters used in patient dose calculations. The data used for analysis were obtained with the Israelita Albert Einstein Hospital (HIAE), Real Português Hospital (RHP) and 3 more institutions located in the United States. The statistical data analysis allowed to observe the parameters behaviors. In general, they were very homogeneous, with errors smaller than 1% confirming the conformance of the TrueBeam accelerators.

A utilização da técnica de teleterapia para tratamento de câncer tem sido usada por anos com bons resultados clínicos. Em meados da década de 90, a remoção do filtro aplainador, item que compõe o cabeçote de um acelerador linear de uso clínico, tem sido objeto de estudos por demonstrar bons resultados no tratamento de alguns tipos de câncer. Técnicas utilizadas como Radioterapia de Intensidade Modulada (IMRT) e Radioterapia Estereotáxica (SRT), mostram-se mais eficazes quando não se utiliza o filtro aplainador. A empresa Varian Oncology lançou em 2012 um acelerador linear de uso clínico capaz de operar com o filtro aplainador (FF) e sem o filtro aplainador (FFF), o TrueBeam. Os objetivos desse trabalho são avaliar a homogeneidade de dois importantes parâmetros utilizados para o cálculo de dose nos pacientes submetidos ao tratamento com esse modelo de acelerador linear, a porcentagem de dose profunda (PDP) e índice de qualidade do feixe (TPR20/10). Os dados fornecidos para a análise foram cedidos pelo Hospital Israelita Albert Einstein (HIAE), Real Hospital Português (RHP) e 3 instituições norte-americanas. Através de uma análise estatística dos dados das instituições citadas pode-se observar melhor o comportamento desses parâmetro que demonstraram-se muito homogêneos e com erros menores que 1% na maioria dos casos, confirmando desse modo que os aceleradores lineares do modelo TrueBeam mantém na maioria das vezes uma boa concordância dos parâmetros analisados. / Teletherapy, radiation therapy with linear accelerators, for cancer treatment has being used for years with good clinical results.Since the 90\'s the removal of the flattening filter, item placed at the gantry of the machine, has shown better results for the treatment of some cancers thus being extensively studied. Treatments with Intensity Modulated RadioTherapy (IMRT) and Sthereotaxic RadioTherapy (SRT) were more efficient without the flattening filter. Varian Oncology released the TrueBeam in 2012, a accelerator capable of operating with or without the flattening filter. The aim of this work is to access homogeneity of the percentage depth dose (PDP) and beam quality index (TPR20/10), two important parameters used in patient dose calculations. The data used for analysis were obtained with the Israelita Albert Einstein Hospital (HIAE), Real Português Hospital (RHP) and 3 more institutions located in the United States. The statistical data analysis allowed to observe the parameters behaviors. In general, they were very homogeneous, with errors smaller than 1% confirming the conformance of the TrueBeam accelerators.

Using Long-Period Fiber Gratings as component of Gain-Flattening filter ofOptical Amplifier, and discuss spectrum of different struture of Long-Period Fiber Gratings. To investigate the spectra characteristics of Long-Period fiber Gratings for designing reference resources. Aiming at different Gain-Flattening filter uses different struture of fiber grating, and the decision of parameter of fiber grating using Genetic Algorithm. Finally delcaring the dataflow of designing filter using Long-Period Fiber Grating and conclusion.In this paper , gain flatttening Cr:YAG optical amplifier spectrum and Erbium-doped optical amplifier spectrum,one achieve 300nm bandwidth and another achieve 40nm.

In order to accelerate logic simulation, it is highly beneficial to simulate the circuit design on FPGA hardware. However, limited hardware resources on FPGAs prevent large designs from being implemented on a single FPGA. Hence there is a need to partition the design and simulate it on a multi-FPGA platform. In contrast to existing FPGA-based post-synthesis partitioning approaches which first completely flatten the circuit and then possibly perform bottom-up clustering, we perform a selective top-down flattening and thereby avoid the potential netlist blowup. This also allows us to preserve the design hierarchy to guide the partitioning and to make subsequent debugging easier. Our approach analyzes the hierarchical design and selectively flattens instances using two metrics based on slack. The resulting partially flattened netlist is converted to a hypergraph, partitioned using a public domain partitioner (hMetis), and reconverted back to a plurality of FPGA netlists, one for each FPGA of the FPGA-based accelerated logic simulation platform. We compare our approach with a partitioning approach that operates on a completely flattened netlist. Static timing analysis was performed for both approaches, and over 15 examples from the OpenCores project, our approach yields a 52% logic simulation speedup and about 0.74x runtime for the entire flow, compared to the completely flat approach. The entire tool chain of our approach is automated in an end-to-end flow from hierarchy extraction, selective flattening, partitioning, and netlist reconstruction. Compared to an existing method which also performs slack-based partitioning of a hierarchical netlist, we obtain a 35% simulation speedup.

<p> Compositionally asymmetric multiple quantum well (AMQW) lasers are used for the demonstration of the gain flattening coating functionality. The gain spectra of the lasers are extracted using a non-linear least square fitting method. An optimum facet reflectance spectrum is calculated for a chosen current. For manufacturability, a modified reflectance spectrum of the gain flattening coating is proposed, in order to achieve operation over a wider spectral range without the 'difficult' gap which was a region where lasing was difficult or impossible to achieve due to insufficient gains at these wavelengths. </p> <p> Silicon oxides films with high, medium, and low refractive indices fabricated in an inductively coupled plasma (ICP) enhanced chemical vapor deposition (CVD) system are chosen as the building blocks of the gain flattening coating. An 18-layer coating is designed by the insertion of needle-like refractive index variation with a few optimization methods applied to minimize the merit function. A laser bar holder is custom designed and fabricated. Experiments and modification on the laser bar holder are carried out for better performance. The 18-layer gain flattening coating is then fabricated in the ICPCVD system with an in-situ spectroscopic ellipsometric measurement. It is observed that the non-lasing gap has disappeared after the coating is applied. Without external feedback, the coated laser shows tuning over 85 nm with the central wavelength of 1593 nm, while the uncoated laser has a non-lasing gap of about 25 nm in the central region of the tuning range of 70 nm. </p> <p> Finally, the coherence length of a low coherent source synthesized from the gain flattening coated AMQW laser is measured by using Michelson interferometer. The highest depth resolution that can be achieved is measured as 40 μm. The power intensity of the synthesized low coherence light source from the gain flattening coated AMQW laser is rendered from the interferogram using fast Fourier transform (FFT). </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

Existing cache organization suffers from the inability to distinguish different types of localities, and non-selectively cache all data rather than making any attempt to take special advantage of the locality type. This causes unnecessary movement of data among the levels of the memory hierarchy and increases in miss ratio. In this dissertation I propose a split data cache architecture that will group memory accesses as scalar or array references according to their inherent locality and will subsequently map each group to a dedicated cache partition. In this system, because scalar and array references will no longer negatively affect each other, cache-interference is diminished, delivering better performance. Further improvement is achieved by the introduction of victim cache, prefetching, data flattening and reconfigurability to tune the array and scalar caches for specific application. The most significant contribution of my work is the introduction of novel cache architecture for embedded microprocessor platforms. My proposed cache architecture uses reconfigurability coupled with split data caches to reduce area and power consumed by cache memories while retaining performance gains. My results show excellent reductions in both memory size and memory access times, translating into reduced power consumption. Since there was a huge reduction in miss rates at L-1 caches, further power reduction is achieved by partially or completely shutting down L-2 data or L-2 instruction caches. The saving in cache sizes resulting from these designs can be used for other processor activities including instruction and data prefetching, branch-prediction buffers. The potential benefits of such techniques for embedded applications have been evaluated in my work. I also explore how my cache organization performs for non-numeric data structures. I propose a novel idea called "Data flattening" which is a profile based memory allocation technique to compress sparsely scattered pointer data into regular contiguous memory locations and explore the potentials of my proposed Spit cache organization for data treated with data flattening method.

Recent studies have shown that even highly-proficient Spanish-English bilinguals, who acquired their second language (L2) in childhood and have little or no foreign accent in English, may require more acoustic information than monolinguals in order to identify English vowels and may have more difficulty than monolinguals in understanding speech in noise or reverberation (Mayo, Florentine, and Buus, 1997; Febo, 2003). One explanation that may account for this difference is that bilingual listeners use acoustic cues for vowel identification differently from monolinguals (Flege, 1995).In this study, we investigated this hypothesis by comparing bilingual listeners use of acoustic cues to vowel identification to that of monolinguals for six American English vowels presented under listening conditions created to manipulate the acoustic cues of vowel formant dynamics and duration. Three listener groups were tested: monolinguals, highly proficient bilinguals, and less proficient bilinguals. Stimulus creation included recording of six target vowels (/i, I, eI, E, ae, A/) in /bVd/ context, spoken in a carrier phrase by four American monolinguals (two females, two males). Six listening conditions were created: 1) whole word, 2) isolated vowel, 3) resynthesized with no change, 4) resynthesized with neutralized duration, 5) resynthesized with flattened formants, and 6) resynthesized with flattened formats and neutralized duration. The resynthesized stimuli were created using high-fidelity synthesis procedures (Straight; Kawahara, Masuda-Katsuse, and Cheveigne 1998) and digital manipulation. A six-alternative forced choice listening task was used. The main experiment was composed of 240 isolated vowel trials and 48 whole word trials.