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The response of an Er/Yb-codoped waveguide ring laser to a sinusoidally modulated pump power is studied. Experimentally, resonance peaks are observed and their dependences on the average pump power and the modulation index are analyzed. For high modulation indexes bistable behaviour is found. Numerically, a good agreement is obtained for the resonance peak frequencies by using a straightforward approximate model and assuming a dependence on the average pump power of the macroscopic Yb ? Er energy-transfer coefficient. This dependence can be related to these mechanisms' performance for high doping and pump levels when examined in a microscopic statistical formalism.

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The objective of this study was to evaluate four cookie formulations which wheat flour was partially substituted by free-fat corn germ flour and/or soy fiber. Baking quality, protein, fat, ash, dietary fiber, hardness, color, Protein Efficiency Ratio PER and Apparent Digestibility in vivo were determined. A trained panel evaluated color, hardness and fracturability of cookies. Dietary fiber of cookies varied from 8.2 to 24.9% and protein from 11.3 to 12.7%. The source and amount of dietary fiber modified physical, sensory, and nutritional properties of cookies. Cookies formulated with 20% corn germ flour gave the highest PER, Digestibility Aparente in vivo, and acceptance by consumers. This study demonstrated the potential use of free-fat corn germ and soy fiber as functional ingredients.

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Cardiomyopathy associated with HIV-1 infection is a well-recognized complication. However, it is unknown whether direct cardiomyocyte infection is involved in the pathogenesis of the cardiomyopathy. An HIV-1-based lentiviral vector and wild-type HIV-1 were used to infect human fetal cardiac myocytes in a primary culture. Quantitative polymerase chain reaction, viral p24 antigen determination, and immunofluorescence were used to detect the synthesis of HIV-1 DNA and proteins after the infection. High-efficiency infection occurred using the HIV-1-based lentiviral vector, although no infection occurred with the wild-type HIV-1 strain. Dual-labeling immunofluorescence for HIV-1 proteins and myosin confirmed that cardiomyocytes were infected. This in vitro analysis suggests that direct myocyte infection with wild-type HIV-1 may not be involved in the pathogenesis of HIV-1 cardiomyopathy. However, HIV-1-based vectors may prove useful for ex vivo cardiovascular gene therapy.

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The objective of this research was to investigate the potential of using rice bran as an ingredient in pastas spaghetti type. Two of the pastas were made with semolina from durum as raw material, supplemented with 10 and 20% rice bran. The other two were made with granular flour and the same percentage of rice bran. Proximate composition of raw material was analyzed. Pastas were elaborated in a local industry. Composition, proximal, color, texture, and sensorial quality of pastas were determined. Protein content (13.9-15.0%), ash (1.47-3.09%) and dietary fiber (6.71-8.45%) of pastas increased according to the percentage of rice bran added. The hardest pastas were those elaborated with semolina from durum wheat and with a 10% of substitution. Also, they were the most yellow. The sensory panel found differences in quality among the pastas evaluated. Pastas with 10% rice bran had the best quality. The results demonstrated that is possible to elaborate pastas with 20% as maximum of rice bran resulting products with high protein, ash and dietetic fiber content, but some undesirable characteristics were given by the rice bran as white spots, wrinkles and color changes.

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Rate equations based on intensity-dependent overlapping factors are integrated to obtain analytic solutions for pump, signal, and amplified spontaneous emission (ASE), even when the coupled signal varies with time. The equations can be applied without the imposition of any restraints on the values of the pump, signal, and ASE powers, the excited-state-absorption cross section, the erbium-density distribution, or other parameters that characterize the fiber. The methods used to calculate pump, signal, and ASE powers are discussed. Experimental techniques to characterize the doped fiber that were based on these analytic expressions are introduced.

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A simple model describing the evolution of pump, signal, and amplified spontaneous emission powers in an erbium-doped silica fiber is presented. The model is based on overlapping factors, depending on pump- and signal-coupled powers, which are systematically studied. Accurate results for gain and amplified spontaneous emission are obtained when this model is used. Experiments to measure the characteristic parameters of the fiber appearing in the model are described. Two main advantages of this model are found: computation time is considerably reduced and fiber characterization does not make it necessary to measure the parameters of the fiber as a function of radial or azimuthal coordinates.

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In the following study, dietary fiber, insoluble (IDF), soluble (SDF) and total (TDF) were determined in cereals and by-products and in commercial cereals products which are found in the national market and promoted as a source of fiber. The Prosky's enzimatic-gravimetric method was used. Results were expressed as g/100g wet basis. Total dietary fiber in cereals and by-products showed a range from 1.18% (poshed rice) to 89.10% (corn bran). For the commercial cereal products, the TDF values varied from 3.73% (rice-sesame cookies) to 34.96% (Breakfast cereal named All Bran). The FDI values always were greater than the SDF values. Based on this fact, FDI values were compared with NDF (Neutral Detergent Fiber) values reported in the scientific literature and in the Venezuelan Food Composition Tables using a regression analysis. FDI values were always greater than NDF values and the correlation factor (r) was high and statistical significance to P < 0.05 for both food groups in study.

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The stress on either the erbium-doped or the normal optical fiber inside a cavity can cause output modulation, wavelength tuning in the gain band, and selection of the transition at 1.53 or 1.56 microm in an erbium-doped optical fiber laser. These phenomena are explained with the birefringence of the optical fiber under stress, the polarization properties of the directional coupler loop, and the condition of the laser oscillation. These phenomena may have some practical use in output power control, wavelength tuning, and sensors.

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In this paper the accuracy in the determination of the period of an oscillating signal, when obtained from the photon statistics time-interval probability, is studied as a function of the precision (the inverse of the cutoff frequency of the photon counting system) with which time intervals are measured. The results are obtained by means of an experiment with a square-wave signal, where the Fourier or square-wave transforms of the time-interval probability are measured. It is found that for values of the frequency of the signal near the cutoff frequency the errors in the period are small.

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In this paper we study the improvement in a laser Doppler velocimetry experiment when the Fourier transform of the time interval probability is measured instead of the intensity correlation function. The errors involved in determination of the velocity are found to be greatly improved for low scattered intensities.

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In this paper we study the possibility of analyzing solutions of mixtures of spherical and cylindrical macro-molecules, impinging on them with laser light and measuring the normalized second-order factorial moment, n((2))(T), of the scattered light. With this method we intend to determine the quotient of concentrations of the two solute fractions or the molecular weight of one of the components. The errors in these measurements are studied by means of a computer simulation method. The validity of the simulation method is experimentally proved with a mixture of two kinds of spherical particles of different size.

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A level-crossing detection method is presented and developed based on measurement of the normalized second factorial moment n((2))(T) of the photon-counting distribution of the resultant fluorescence. Expression n((2))(T) is obtained, and the errors expected in the determination of signal width and crossing field are theoretically studied. The validity of the approximations performed to establish the theoretical model is proved by an experiment with a square-wave periodically modulated light beam.