MEASUREMENT OF SOLID SLURRY FLOW VIA CORRELATION OF ELECTROMAGNETIC FLOW METER, ELECTRICAL RESISTANCE TOMOGRAPHY AND MECHANISTIC MODELLING

The study presented here was carried out to obtain the actual solids flow rate by the combination of electrical resistance tomography and electromagnetic flow meter. A new in-situ measurement method based on measurements of the Electromagnetic Flow Meters (EFM) and Electrical Resistance Tomography (ERT) to study the flow rates of individual phases in a vertical flow was proposed. The study was based on laboratory experiments that were carried out with a 50 mm vertical flow rig for a number of sand concentrations and different mixture velocities. A range of sand slurries with median particle size from 212 mu m to 355 mu m was tested. The solid concentration by volume covered was 5% and 15%, and the corresponding density of 5% was 1078 kg/m(3) and of 15% was 1238 kg/m(3). The flow velocity was between 1.5 m/s and 3.0 m/s. A total of 6 experimental tests were conducted. The equivalent liquid model was adopted to validate in-situ volumetric solids fraction and calculate the slip velocity. The results show that the ERT technique can be used in conjunction with an electromagnetic flow meter as a way of measurement of slurry flow rate in a vertical pipe flow. However it should be emphasized that the EFM results must be treated with reservation when the flow pattern at the EFM mounting position is a non-homogenous flow. The flow rate obtained by the EFM should be corrected considering the slip velocity and the flow pattern.

Statistical and econometric analysis of the treatment of HIV/AIDS

The epidemic of HIV/AIDS in the United States is constantly changing and evolving, starting from patient zero to now an estimated 650,000 to 900,000 Americans infected. The nature and course of HIV changed dramatically with the introduction of antiretrovirals. This discourse examines many different facets of HIV from the beginning where there wasn't any treatment for HIV until the present era of highly active antiretroviral therapy (HAART). By utilizing statistical analysis of clinical data, this paper examines where we were, where we are and projections as to where treatment of HIV/AIDS is headed.

Chapter Two describes the datasets that were used for the analyses. The primary database utilized was collected by myself from an outpatient HIV clinic. The data included dates from 1984 until the present. The second database was from the Multicenter AIDS Cohort Study (MACS) public dataset. The data from the MACS cover the time between 1984 and October 1992. Comparisons are made between both datasets.

Chapter Three discusses where we were. Before the first anti-HIV drugs (called antiretrovirals) were approved, there was no treatment to slow the progression of HIV. The first generation of antiretrovirals, reverse transcriptase inhibitors such as AZT (zidovudine), DDI (didanosine), DDC (zalcitabine), and D4T (stavudine) provided the first treatment for HIV. The first clinical trials showed that these antiretrovirals had a significant impact on increasing patient survival. The trials also showed that patients on these drugs had increased CD4+ T cell counts. Chapter Three examines the distributions of CD4 T cell counts. The results show that the estimated distributions of CD4 T cell counts are distinctly non-Gaussian. Thus distributional assumptions regarding CD4 T cell counts must be taken, into account when performing analyses with this marker. The results also show the estimated CD4 T cell distributions for each disease stage: asymptomatic, symptomatic and AIDS are non-Gaussian. Interestingly, the distribution of CD4 T cell counts for the asymptomatic period is significantly below that of the CD4 T cell distribution for the uninfected population suggesting that even in patients with no outward symptoms of HIV infection, there exists high levels of immunosuppression.

Chapter Four discusses where we are at present. HIV quickly grew resistant to reverse transcriptase inhibitors which were given sequentially as mono or dual therapy. As resistance grew, the positive effects of the reverse transcriptase inhibitors on CD4 T cell counts and survival dissipated. As the old era faded a new era characterized by a new class of drugs and new technology changed the way that we treat HIV-infected patients. Viral load assays were able to quantify the levels of HIV RNA in the blood. By quantifying the viral load, one now had a faster, more direct way to test antiretroviral regimen efficacy. Protease inhibitors, which attacked a different region of HIV than reverse transcriptase inhibitors, when used in combination with other antiretroviral agents were found to dramatically and significantly reduce the HIV RNA levels in the blood. Patients also experienced significant increases in CD4 T cell counts. For the first time in the epidemic, there was hope. It was hypothesized that with HAART, viral levels could be kept so low that the immune system as measured by CD4 T cell counts would be able to recover. If these viral levels could be kept low enough, it would be possible for the immune system to eradicate the virus. The hypothesis of immune reconstitution, that is bringing CD4 T cell counts up to levels seen in uninfected patients, is tested in Chapter Four. It was found that for these patients, there was not enough of a CD4 T cell increase to be consistent with the hypothesis of immune reconstitution.

In Chapter Five, the effectiveness of long-term HAART is analyzed. Survival analysis was conducted on 213 patients on long-term HAART. The primary endpoint was presence of an AIDS defining illness. A high level of clinical failure, or progression to an endpoint, was found.

Chapter Six yields insights into where we are going. New technology such as viral genotypic testing, that looks at the genetic structure of HIV and determines where mutations have occurred, has shown that HIV is capable of producing resistance mutations that confer multiple drug resistance. This section looks at resistance issues and speculates, ceterus parabis, where the state of HIV is going. This section first addresses viral genotype and the correlates of viral load and disease progression. A second analysis looks at patients who have failed their primary attempts at HAART and subsequent salvage therapy. It was found that salvage regimens, efforts to control viral replication through the administration of different combinations of antiretrovirals, were not effective in 90 percent of the population in controlling viral replication. Thus, primary attempts at therapy offer the best change of viral suppression and delay of disease progression. Documentation of transmission of drug-resistant virus suggests that the public health crisis of HIV is far from over. Drug resistant HIV can sustain the epidemic and hamper our efforts to treat HIV infection. The data presented suggest that the decrease in the morbidity and mortality due to HIV/AIDS is transient. Deaths due to HIV will increase and public health officials must prepare for this eventuality unless new treatments become available. These results also underscore the importance of the vaccine effort.

The final chapter looks at the economic issues related to HIV. The direct and indirect costs of treating HIV/AIDS are very high. For the first time in the epidemic, there exists treatment that can actually slow disease progression. The direct costs for HAART are estimated. It is estimated that the direct lifetime costs for treating each HIV infected patient with HAART is between $353,000 to $598,000 depending on how long HAART prolongs life. If one looks at the incremental cost per year of life saved it is only $101,000. This is comparable with the incremental costs per year of life saved from coronary artery bypass surgery.

Policy makers need to be aware that although HAART can delay disease progression, it is not a cure and HIV is not over. The results presented here suggest that the decreases in the morbidity and mortality due to HIV are transient. Policymakers need to be prepared for the eventual increase in AIDS incidence and mortality. Costs associated with HIV/AIDS are also projected to increase. The cost savings seen recently have been from the dramatic decreases in the incidence of AIDS defining opportunistic infections. As patients who have been on HAART the longest start to progress to AIDS, policymakers and insurance companies will find that the cost of treating HIV/AIDS will increase.

Análise das alterações decorrentes do envelhecimento na mecânica respiratória pela técnica de oscilações forçadas

O crescimento do percentual de idosos na população ocorre mundialmente tornando necessário conhecer o impacto do processo de envelhecimento, neste contexto, do sistema respiratório. O desconhecimento do impacto do envelhecimento associado a diferentes graus de exposição a poluentes e a presença de comorbidade(s) dificulta a diagnose das pneumopatias acarretando aos idosos piora da qualidade de vida. São vantagens da Técnica de Oscilações Forçadas (FOT): alto potencial de aplicação em idosos, fácil realização, análise detalhada da mecânica respiratória, desempenho de papel complementar, bem como de alternativa na impossibilidade de realização dos exames tradicionais. Foi realizado um estudo experimental comparativo que objetivou investigar o impacto do envelhecimento no sistema respiratório pela FOT e pela espirometria entre grupos de diferentes faixas etárias, sendo a idade a variável independente e as variáveis dependentes, os parâmetros oscilométricos resistência em regime contínuo (R0) e das vias aéreas centrais (Rm), inclinação da resistência (S), frequência de ressonância (fr), reatância média (Xm), complacência dinâmica (Cdin,sr) e os parâmetros espirométricos (VEF1, CVF, VEF1/CVF e FEF/CVF). Foram realizados entrevista, exame clínico, radiografia torácica, avaliação da mecânica respiratória pela FOT e da função pulmonar pela espirometria. 255 indivíduos com idades entre 20 e 86 anos foram entrevistados. Destes, 175 foram excluídos, restando os 80 voluntários analisados, que foram divididos em 6 grupos de acordo com a faixa etária (A: 20 a 29 anos; B: 30 a 39 anos; C: 40 a 49 anos; D: 50 a 59 anos; E: 60 a 69 anos; F: 70 anos ou mais). Foram utilizados os testes de Shapiro-Wilkins, na avaliação da normalidade dos dados biométricos em cada grupo, Oneway ANOVA, na comparação entre os grupos, e Tukey HSD na comparação entre as classes subjacentes. A análise da associação entre duas variáveis foi realizada inicialmente pela regressão univariada entre os parâmetros oscilométricos, a idade e a altura. A regressão múltipla entre os parâmetros oscilométricos, idade e altura foi realizada em conjunto. Foi realizada a análise de confundimento ou modificação de efeito sobre o parâmetro altura na relação entre a idade e os parâmetros oscilométricos. A correção pelo fator altura foi realizada quando sua análise apresentava fator de confundimento. Quanto aos parâmetros resistivos, não foram observadas alterações em R0 e Rm com o envelhecimento enquanto que o declínio observado em S é discreto e não-significativo. Em relação aos parâmetros reativos, verificouse que Cdin,sr e Xm diminuem enquanto que fr aumenta com o processo de envelhecimento. Todas estas alterações são significativas. Todavia, a diminuição da Cdin,sr não apresenta relação com a idade e sim com a altura, que constituiu modificação do efeito. Nos demais parâmetros oscilométricos, a altura constituiu fator de confundimento. Quanto à espirometria, observou-se declínio significativo do VEF1, do VEF1/CVF e da CVF. O índice FEF/CVF apresentou declínio nãosignificativo. Concluindo, a resistência do sistema respiratório e a complacência dinâmica não se modificam enquanto a homogeneidade do sistema respiratório diminui com o processo de envelhecimento.

Condições mecânicas do sistema respiratório em adultos com fibrose cística: estudo pela espirometria, pletismografia e técnica de oscilações forçadas

A fibrose cística (FC) é a doença autossômica recessiva mais comum na população branca que leva à redução na expectativa de vida. A doença pulmonar é a maior causa de morbidade e mortalidade. A relevância do presente estudo se dá diante de alguns fatores: aumento drástico da sobrevida média nos últimos 60 anos na FC, a fisiopatologia pulmonar não é bem compreendida, ausência de estudos reportados na literatura, até o momento, utilizando a técnica de oscilações forçadas (TOF) exclusivamente em adultos com FC. Assim sendo os objetivos deste estudo são: analisar as alterações da mecânica respiratória em adultos com FC através da espirometria, pletismografia e TOF; correlacionar os resultados da TOF aos espirométricos e pletismográficos e avaliar a sensibilidade e especificidade da TOF nestes indivíduos. É um estudo de corte transversal descritivo, no qual foram analisados dois grupos de indivíduos: controle (n=23) e FC (n=27). Os resultados foram expressos através média desvio-padrão. As técnicas funcionais respiratórias foram realizadas na seguinte sequência: TOF, espirometria, pletismografia. Na pletismografia foram avaliados os parâmetros: CPT (capacidade pulmonar total), CRF (capacidade residual funcional) e VR (volume residual), CRF/CPT e VR/CPT, resistência (Rva) e condutância específica das vias aéreas (SGva). Na espirometria: volume expiratório forçado no primeiro segundo (VEF1), capacidade vital forçada (CVF), fluxo expiratório entre 25% e 75% (FEF25%-75%) da CVF (FEF25%-75%) e razões VEF1/CVF (%) e FEF/CVF (%). Na TOF: propriedades resistivas do sistema respiratório- R0 (resistência no intercepto), Rm (resistência média) e S (inclinação da reta de resistência) e propriedades reativas: Cdin,sr (complacência dinâmica do sistema respiratório), Xm (reatância média), frequência de ressonância (fr); e o módulo da impedância em 4 Hz (׀Zrs4Hz׀). Na espirometria o distúrbio ventilatório obstrutivo (DVO) com CVF reduzida foi predominante, com marcante redução do FEF25%-75% no grupo FC (p<0,0001) em relação ao controle. Na pletismografia: destacou-se a elevação de VR, na presença de CPT normal e elevação da Rva e redução da SGva no grupo FC. Alterações da TOF ocorridas no grupo FC em relação ao controle: aumento de R0 e Rm (p<0,0001) e fr (p<0,0002), relacionados à obstrução das vias aéreas; redução de S (p<0,0006), Xm (p<0,0001) associadas à não-homogeneidade do sistema respiratório e Cdin,sr (p<0,0001), relacionada à redução da complacência pulmonar; aumento do módulo da impedância em 4 Hz (׀Zrs4Hz׀) (representando a carga mecânica total do sistema respiratório) resultante da interação das demais alterações da TOF citadas. Os parâmetros da TOF apresentaram correlações muito boas com a espirometria e moderadas com a pletismografia. Rm foi o único parâmetro que não se relacionou com nenhuma destas técnicas. A sensibilidade e especificidade da TOF em adultos com FC apresentaram valores elevados, sobretudo nos parâmetros reativos, em especial, Xm (85,2% e 73,9% respectivamente e área sob a curva de 0,86).

Electrical resistance and thermoelectric power of the metastable phases in tellurium-base alloys

By using techniques of rapid quenching from the melt, metastable phases have been obtained in ternary alloys which contain tellurium as a major component and two of the three noble metals (Cu, Ag, Au) as minor components. The metastable phases found in this investigation are either simple cubic or amorphous. The formation of the simple cubic phase is discussed. The electrical resistance and the thermoelectric power of the simple cubic alloy (Au₃₀Te₇₀) have been measured and interpreted in terms of atomic bondings. The semiconducting properties of a metastable amorphous alloy (Au₅Cu₂₅Te₇₀) have been measured. The experimental results are discussed in connection with a theoretical consideration of the validity of band theory in an amorphous solid. The existence of extrinsic conduction in an amorphous semiconductor is suggested by the result of electrical resistance and thermoelectric power measurements.

Radio frequency studies of surface resistance and critical magnetic field of type I and type II superconductors

The surface resistance and the critical magnetic field of lead electroplated on copper were studied at 205 MHz in a half-wave coaxial resonator. The observed surface resistance at a low field level below 4.2°K could be well described by the BCS surface resistance with the addition of a temperature independent residual resistance. The available experimental data suggest that the major fraction of the residual resistance in the present experiment was due to the presence of an oxide layer on the surface. At higher magnetic field levels the surface resistance was found to be enhanced due to surface imperfections.

The attainable rf critical magnetic field between 2.2°K and T_c of lead was found to be limited not by the thermodynamic critical field but rather by the superheating field predicted by the one-dimensional Ginzburg-Landau theory. The observed rf critical field was very close to the expected superheating field, particularly in the higher reduced temperature range, but showed somewhat stronger temperature dependence than the expected superheating field in the lower reduced temperature range.

The rf critical magnetic field was also studied at 90 MHz for pure tin and indium, and for a series of SnIn and InBi alloys spanning both type I and type II superconductivity. The samples were spherical with typical diameters of 1-2 mm and a helical resonator was used to generate the rf magnetic field in the measurement. The results of pure samples of tin and indium showed that a vortex-like nucleation of the normal phase was responsible for the superconducting-to-normal phase transition in the rf field at temperatures up to about 0.98-0.99 T_c' where the ideal superheating limit was being reached. The results of the alloy samples showed that the attainable rf critical fields near T_c were well described by the superheating field predicted by the one-dimensional GL theory in both the type I and type II regimes. The measurement was also made at 300 MHz resulting in no significant change in the rf critical field. Thus it was inferred that the nucleation time of the normal phase, once the critical field was reached, was small compared with the rf period in this frequency range.

Modified porous silica antireflective coatings with laser damage resistance for Ti:sapphire

Porous SiO2 antireflective (AR) coatings are prepared from the colloidal silica solution modified with methyltriethoxysilane (MTES) based on the sol-gel route. The viscosity of modified silica suspensions changes but their stability keeps when MTES is introduced. The refractive indices of modified coatings vary little after bake treatment from 100 to 150 Celsius. The modified silica coatings on Ti:sapphire crystal, owning good homogeneity, display prominent antireflective effect within the laser output waveband (750-850 nm) of Ti:sapphire lasers, with average transmission above 98.6%, and own laser induced damage thresholds (LIDTs) of more than 2.2 J/cm2 at 800 nm with the pulse duration of 300 ps.

Participação do estresse oxidativo na lesão pulmonar induzida por lipopolissacarídeo: repercussões inflamatórias estruturais e funcionais

O objetivo do presente estudo foi investigar o envolvimento do estresse oxidativo na lesão pulmonar aguda (LPA) induzida por lipopolissacarídeo (LPS) e as repercussões inflamatórias, estruturais e funcionais, através de análises bioquímicas de estresse oxidativo, prova de função pulmonar, análise histológica e RT-PCR para citocinas e fatores de transcrição pró-inflamatórios. Na primeira etapa foram utilizados camundongos machos C57BL6 foram divididos em sete grupos: Grupo controle (CTR) (50 μL de solução fisiológica) administrados via intratraqueal [it], LPS 6 horas (10 μL de LPS) [it], LPS 12 horas (10 μL de LPS) [it], LPS 24 horas (10 μL de LPS) [i], LPS 48 horas (10 μL de LPS). Para verificar que as alterações observadas eram estresse oxidativo dependentes camundongos machos C57BL6 foram pré-tratados com N-acetilcisteína (NAC) 1 hora antes do estímulo com LPS e sacrifícados 24 horas depois do estímulo com LPS. Os animais foram divididos da seguinte forma: Grupo LPS 24 horas (10 μL) [it], grupo NAC 40 mg/kg (gavagem) + LPS (10 μL) [it] e grupo NAC 100 mg/kg (gavagem) + LPS (10 μL) [it]. O sistema antioxidante enzimático protegeu o pulmão do estresse oxidativo nas primeiras 12 horas. O estresse oxidativo foi caracterizado em 24 horas e em 48 horas observou-se falência do sistema antioxidante enzimático. Parâmetros de função pulmonar se mostraram alterados nos grupo estimulados com LPS principalmente no grupo LPS. A elastância (p<0,001), resistência de via aérea periférica (ΔP2) (p<0,001), resistência de via aérea central (ΔP1) (p<0,001) e resistência de via aérea total (ΔPtot) (p<0,001) se mostraram principlamente alteradas no grupo LPS 24 horas. O pré-tratamento com NAC impediu o aumento dos parâmetros de elastância (p<0,001), resistência de via aérea periférica (ΔP2) (p<0,001) resistência de via aérea central (ΔP1) (p<0,05) e resistência de via aérea total (ΔPtot) (p<0,001) comparado com o grupo LPS 24 horas. As alterações histológicas como espessamento de septo alveolar, influxo de células inflamatórias e hemorragia mostraram-se tempo dependentes. O pré-tratamento NAC impediu as alterações observadas nos grupo estimulados com LPS. Alterações inflamatórias foram observadas no grupo estimulado com LPS como IL-6 (p<0,001), iNOS (p<0,001), COX2 (p<0,05), TNF-α (p<0,001) e NFκB (p<0,001) quando comparados ao grupo controle. O pré-tratamento com NAC impediu o aumento desses parâmetros como IL-6 (p<0,001), iNOS (p<0,001), COX2 (p<0,05), TNF-α (p<0,05) e NFκB (p<0,001) quando comparados ao grupo LPS 24 horas. Nossos resultados sugerem que o estresse oxidativo desempenha um papel importante nas respostas inflamatórios, estruturais e funcionais no modelo de LPA induzido por LPS e que essas alterações são estresse oxidativo dependentes.