Bulk Index Research Articles

Faecal bulking index: A physiological basis for dietary management of bulk in the distal colon

Bulk in the distal colon provides protection against a range of large bowel disorders, but a simple standardized measure of the relative bulking efficacy of foods, for use in dietary management of distal colonic bulk, has not been available. This paper describes a faecal bulking index (FBI) for standardized measurement of the relative colonic bulking efficacy of foods relative to a reference material. Faecal bulking index is defined as the mass of fully rehydrated faecal matter accumulated by the distal colon per gram of a food consumed, as a percentage of the matter accumulated from the same weight of a reference food. The FBI of foods was measured after feeding adult rats at moderate levels by partially or completely replacing sucrose in a baseline diet already containing mixed dietary fiber. Faeces were collected, dried, weighed, allowed to imbibe water until fully rehydrated, reweighed and their mass and water holding capacity measured. The FBI was calculated as the increase over baseline in rehydrated faecal mass induced by a test food as a percentage of the increase due to wheat bran (reference). The FBI values were measured for 69 diets including breakfast cereals, breads and other bakery products, fruits, vegetables, food ingredients and polysaccharides. Values for most foods ranged between almost zero for some starch-based foods to about 50 for wheat bran-enriched breakfast cereals, but laxatives based on fermentation-resistant hydrated polysaccharide had FBI values well in excess of 100 (FBI for psyllium = 500). The FBI values allow foods to be ranked according to their faecal bulking efficacy on an equal edible weight basis. They can also be used to calculate the bulking action of any amount of food in terms of equivalents to a reference material such as wheat bran. Wheat bran equivalents allow the cumulative intake of potential distal colonic bulk to be monitored for single foods or mixed meals, and shortfalls to be quantified for dietary modification or supplementation. Measures such as FBI or wheat bran equivalents would prove more useful than dietary fiber in controlling 'functional foods' promoted as effective bulking agents.

Wavelength trimming of a microring resonator filter by means of a UV sensitive polymer overlay

Trimming of the resonant wavelength of a vertically coupled glass microring resonator channel dropping filter with a photo-induced refractive index change in a dip coated polymer overlay is reported. In this letter, the glass microring resonator has a radius of 19 /spl mu/m, a free-spectral range of 10 nm, and a Q value of 800. The maximum wavelength shift observed is 9 nm, which is yielded through an absolute bulk index change in the polymer of 0.044. Trimming is a continuous function of exposure time and dose.

Quantitative Interpretation of the Response of Surface Plasmon Resonance Sensors to Adsorbed Films

A simple but quantitative mathematical formalism for interpretation of surface plasmon resonance (SPR) signals from adsorbed films of a wide variety of structures is presented. It can be used to estimate adsorbed film thicknesses, surface coverages, or surface concentrations from the SPR response over the entire range of film thicknesses without relying on calibration curves of response versus known thicknesses or surface concentrations. This formalism is compared to more complex optical simulations. It is further tested by (1) calibrating the response of two SPR spectrometers to changes in bulk index of refraction, (2) using these calibrations with this formalism to predict responses to several well-characterized adlayer structures (alkanethiolates and serum albumin on gold, propylamine on COOH-functionalized gold), and then (3) comparing these predictions to measured SPR responses. Methods for estimating the refractive index of the adlayer material are also discussed. Detection limits in both bulk and a...

Raman-based measurements of optical properties of thin solid films: application to amorphous diamond

The potentialities of Raman spectroscopy to measure optical properties of thin solid films are considered. A new approach based on the analysis of interference-induced modification of the Raman scattering from the substrate material together with the normal reflection coefficient is proposed. It is shown that the method provides the absorption coefficient and refractive index of the film bulk with high spatial resolution and accuracy, and it can be applied to various transparent thin films. The developed approach is used to measure optical properties of amorphous diamond films deposited onto crystalline silicon. In the case of the amorphous diamond films deposited with a mass-separated ion beam, a straightforward correlation between the absorption coefficient and Raman spectra is obtained, which can be also used to estimate the optical properties. For the films deposited with pulsed cathodic arc discharge, such a relation appears to be more complex, which possibly indicates extensive variations of the sp 2 clusterization in the latter deposition method.

Studies on the reproductive biology of the Donkey's ear abalone, Haliotis asinina Linné

The sex ratio, initial size at sexual maturity, spawning period, time interval between successive spawnings and fecundity of the Donkey's ear abalone, Haliotis asinina were studied. The sex ratio of wild abalone (>60 mm shell length) collected from Panagatan Cays, Antique, Philippines was approximately 1:1. Sexual maturity was first attained at a size of 35.0 mm and 35.9 mm for hatchery-reared male and female abalone, respectively, and 40.6 mm for wild-caught male and female specimens. Based on calculated gonad bulk indices and histological observations, wild-caught abalone appeared capable of spawning during most months of the study period except June for males and May–June for females, during which most specimens collected were at a resting stage. This abalone species is a serial spawner with an asynchronous spawning behavior. Hatchery-reared abalone have short time intervals between successive spawnings of 13–15 days. Ripe females measuring 58.1–69 mm in shell length may release about 150,000 to 600,000 eggs per spawning.

Direct measurement of refractive-index dispersion using a time-delayed technique

We describe a new way to measure the refractive index of dielectric materials using a time-resolved correlation method. By measuring the time delay of femtosecond pulse trains through a dielectric material, we obtain the refractive index of the material. This technique is direct, less surface sensitive, and precise to four digits. Consequently, it gives a true bulk index value. We apply this technique to measure the refractive index of fused silica, InP, and GaAs in the near infrared spectral regime.

Development of new coated glasses assisted by a computer program

This paper presents the performances of our computer code developed to minimize research efforts required for the development of new coatings on glasses. Computer assisted investigations of the optical and energitical properties of stackings on glass allow the selection of the most promising multilayers. Optical and energetical constraints can be encountered by optimizing the materials and the thicknesses of the layers. The stability of the properties of the multilayers versus thickness variations during production, or versus observation angle can be predicted. The quality of all these predictions is strongly dependent on the knowledge of the optical indices of thin film materials. The use of bulk indices may lead to predictions that are not correct for thin film stackings in practice. A subroutine of the program allows the determination of thin film optical indices.

Lognormal Modes of Dielectric Optical Waveguides

It is shown that, at a critical point where the effective refractive index of a mode coincides with the bulk index of a cladding region, optical waveguide modes exhibiting a lognormal feature are supportable for a hyperlongrange refractive-index profile. As a typical example of waveguides that support lognormal modes a parabolic-index core surrounded by a depressed-index cladding is presented.

Optical functions of bulk and epitaxial GaSb from 0.0025 to 6 eV

The complex refraction index and dielectric functions of GaSb bulk (both p and n-type) and MBE film were accurately determined from 0.0025 to 6 eV by using reflectance and ellipsometric spectroscopies. These functions, which satisfy the Kramers-Kronig causality relations, appear independent on the doping (≤2×10 17cm −3) in the interband transition region. In particular, in comparison with previous data from literature, the E 0 fundamental gap is well evidenced for all the samples. Moreover, the optical functions around the gap are very different from those previously reported and the refractive index was modeled by a Sellmeier dispersion relation. The free-carriers instead strongly influence the far-infrared restrahlen region due to the phonon-plasmon coupling. In this range the optical functions were well fitted by Drude-Lorentz oscillators.

Aspects of the biology of the abaloneHaliotis midae(Linne, 1758) on the east coast of South Africa. 2. Reproduction

The South African abalone Haliolis midae is a dioecious, broadcast spawner with a high fecundity. Histological examination and gonad bulk indices showed that individuals are iteroparous, asynchronous spawners, and that the breeding season extends from March through to October, spawning peaking between April and June. The structure of the ovary and testis, and the process of gametogenesis are typical of haliotid species. Males and females spawn partially or totally, with atresia of residual gametes occurring after spawning. No resting stage was apparent and gonadal recrudescence began immediately after spawning. Sexual maturity was first attained at 20–25 mm shell width, and the size at 50% sexual maturity was attained at approximately 35 mm shell width in all of the populations studied, a size considerably lower than that of previously studied West Coast populations of H. midae.

Accurate refractive index measurements of doped and undoped InP by a grating coupling technique

Accurate measurements of InP refractive indices in the 1300–1600 nm wavelength range are reported. They are obtained using the grating coupling technique within an asymmetrical slab waveguide where an intrinsic InP guiding layer was grown on a doped InP substrate (N=2×1018 cm−3). Modal indices are obtained with an absolute precision of a few 10−4 from either guided or reflected waves. Bulk refractive indices of intrinsic and N-doped InP are then deduced from the allowed modes propagating in the layered structure. With sample temperature maintained to within 0.01 K, InP bulk indices are obtained with a typical accuracy of 5×10−4. Furthermore, a (2.02±0.02) 10−4 K−1 refractive index temperature coefficient has been measured for bulk InP at room temperature.

Algebraically decaying modes of dielectric planar waveguides

We show analytically that, at a critical point where the effective refractive index of a mode coincides with the bulk index of a substrate region, for certain graded-index planar waveguides there exists a family of bound modes with algebraic (power-law) tails in the evanescent field.

Measurement of the refractive index of AlxGa1−xAs and the mode indices of guided modes by a grating coupling technique

We have determined the index of refraction of AlxGa−xAs over the wavelength range 0.76–1.15 μm, and the composition range 0≤x<0.33, using a grating to couple light into waveguides. We find the mode indices of multimode slab waveguides from the coupling angle and grating period, then calculate the bulk indices of the core and cladding materials by a root searching technique using the analytical formula for the effective index of a guided mode. The method gives the core index within ±0.001, and the cladding index within ±0.01. We are in agreement with high precision index values for GaAs in the literature, confirming the method. We are in substantial agreement with literature values for AlGaAs but find a significant systematic difference in the composition dependence. An analysis of measurement uncertainties shows that the determination of composition is the dominant variable.

Spectroscopic Ellipsometry Characterization of La2Ti2O7 Thin Films

ABSTRACTOptical properties of La2Ti2O7 thin films were investigated by spectroscopie ellipsometry and compared to those of bulk sintered ceramics. Thin films were prepared by pulsed laser deposition (PLD) from bulk targets. To separate the effects of thickness, porosity, and index of refraction on observed Ψ and δspectra in thin films, a Cauchy model for n vs. λ was developed from sintered samples, with known porosity. Assuming the effective bulk index of refraction followed the rule of mixtures, corrected models for La2Ti2O7 without porosity were used to determine thickness and porosity of thin films as a function of fabrication parameters such as laser energy, substrate material and temperature. Ellipsometry models were tested and refined through XRD, EDX, ESCA, and SEM.

Waveguides in lithium iodate by means of proton implantation

Planar waveguides are built up (around 300 K) in lithium iodate by means of proton implantation. The waveguide properties are investigated by a prism coupling technique (m-lines spectroscopy). Both TE and TM modes are used to investigate the ordinary and extraordinary indices. The reconstructed index profiles obtained with inverse WKB method, are compared to the ion concentration profile as determined by simulation (TRIM). All the measured effective index values are smaller than these of the bulk indices. Moreover, the optical barrier is relevant to a maximum index change of about 0.03.

Bulk and surface singularity indices in the alkali metals.

Photoemission data from (110) films of Li, Na, and Rb, in which the signal from the first atomic layer is well resolved, show that the core-hole-screening singularity index is \ensuremath{\sim}40% larger at the surface than in the bulk for all three metals. This result, which is indicative of the more atomiclike character of metal surface atoms, in general, is particularly large for the alkali metals because their conduction-electron screening is mainly s-like. In addition to quantifying the difference in screening at the surface, the data provide bulk singularity indices of 0.22, 0.16, and 0.14 for Li, Na, and Rb, respectively. These new values are in better agreement with theory and with the threshold exponents than earlier values derived from incompletely bulklike x-ray photoemission data.

Optical nonlinear effects in GaAs/GaAlAs Bragg reflectors

Band filling effects are used to modify the absorption and refractive index of bulk GaAs/Ga1−xAlxAs layers in a Bragg reflector in the wavelength region between the band gap of the two materials. Significant reflectivity modifications are observed in a subpicosecond regime.

Bulk System Reliability-Measurement and Indices

Methods and indices are presented for measuring the actual bulk power system reliability of individual utilities. Categories of unreliability events are identified for measurement, and locations in the bulk system where measurements can be made are suggested. Data requirements and indices calculations are discussed. The proposed measurement system uses data available from utility operating reports, so that the cost of implementation is expected to be modest. >

Bulk system reliability-measurement and indices

Methods and indices are presented for measuring the actual bulk power system reliability of individual utilities. Categories of unreliability events are identified for measurement, and locations in the bulk system where measurements can be made are suggested. Data requirements and indices calculations are discussed. The proposed measurement system uses data available from utility operating reports, so that the cost of implementation is expected to be modest.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Behaviour of a novel cylindrical glass fibre optical coupler buried in KDP

Electro-optic intensity modulation is reported for the first time in a device consisting of a glass fibre directional coupler with an active KDP cladding. Tests suggest that, within about 0.5μm of the fibre surface, the KDP crystal has its bulk index, but a reduced electro-optic coefficient