RESUMO
This study investigated temporal variations in the potential maximum quantum yield of photosystem II (F(v)/F(m) ratio) and growth-phase dependent cellular protein expressions of Chattonella antiqua under laboratory conditions. Despite the culture conditions, significant positive correlations between the F(v)/F(m) ratio and daily growth rate were observed. Threshold F(v)/F(m) ratios associated with positive cell growth were calculated to be >0.44, >0.44, and >0.37, and those associated with active cell growth (growth rate >0.5 div. d(-1)) were >0.58, >0.60, and >0.49 under control culture, low nutrient and intense light conditions, respectively. Proteome profiles obtained by two-dimensional gel electrophoresis (2-DE) indicated that 42 protein spots were differentially expressed at various growth phases of C. antiqua, which indicates changes in cellular physiological status throughout the growth cycle, and suggests that oxygen evolving enhancer 1 and 2-cysteine peroxiredoxin play roles in maintaining the positive growth of C. antiqua.
Assuntos
Proteínas de Algas/metabolismo , Peroxirredoxinas/metabolismo , Fotossíntese/genética , Complexo de Proteína do Fotossistema II/metabolismo , Estramenópilas/crescimento & desenvolvimento , Estramenópilas/genética , Proteínas de Algas/genética , Sequência de Aminoácidos , Clorofila/fisiologia , Eletroforese em Gel Bidimensional , Expressão Gênica , Perfilação da Expressão Gênica , Concentração de Íons de Hidrogênio , Luz , Dados de Sequência Molecular , Peroxirredoxinas/genética , Complexo de Proteína do Fotossistema II/genética , Homologia de Sequência de Aminoácidos , Estramenópilas/metabolismoRESUMO
The physical characteristics of a direct amorphous Selenium (a-Se) digital fluoroscopy and radiography system were investigated. Pre-sampled modulation transfer functions (MTF) were measured using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform of uniformly exposed samples. The MTFs of direct digital radiography systems showed significantly higher values than those of indirect digital radiography and screen-film systems. The direct digital radiography systems showed higher noise levels compared with those of indirect systems under roughly the same exposure conditions. Contrast-detail analysis was performed to compare detection by direct digital radiography systems with that of the screen-film (FUJI HG-M2/UR2) systems. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that digital contrast-detail curves and IQF are, on average, are equal those of the screen-film system.
Assuntos
Imagens de Fantasmas , Intensificação de Imagem Radiográfica , Análise de Fourier , Intensificação de Imagem Radiográfica/instrumentação , Intensificação de Imagem Radiográfica/métodos , Ecrans Intensificadores para Raios XRESUMO
The physical characteristics of a clinical amorphous silicon-based flat-panel imager for full-field digital mammography were investigated. Pre-sampled modulation transfer functions (MTF) were measured by using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform. The MTFs of full-field digital mammography systems showed significantly higher values than those of the computed radiography (CR) system. The full-field digital mammography system showed a lower noise level than that of the CR system under the same exposure conditions. Contrast detail analysis has been performed to compare the detectability of the full-field digital mammography system with that of the screen-film (Min-R 2000/Min-R 2000) system. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that the digital contrast-detail curves and IQF, on average, are superior to those of the screen-film system.
Assuntos
Mamografia/instrumentação , Intensificação de Imagem Radiográfica/instrumentação , Análise de Fourier , Imagens de Fantasmas , SilícioRESUMO
The authors evaluated a nonenhanced magnetic resonance (MR) angiographic technique that allows separation of arteries from veins. In 15 healthy subjects, peripheral MR angiography was performed with readout flow-spoiled gradient pulses in electrocardiography-triggered three-dimensional half-Fourier fast spin-echo MR imaging. Appropriate flow-spoiled gradient pulses were measured and applied in the three-dimensional acquisition to differentiate arteries and veins in the peripheral vasculature. Subtraction of the diastolic bright-blood arteries from the systolic black-blood arteries allowed visualization of the arteries by cancelling the veins, which are constantly depicted as bright blood throughout the cardiac cycle. Stronger flow-spoiled gradient pulses improved the depiction of slow-flow arteries even in the distal foot and hand vessels.
