The transient regime of a multiwavelength pyrometer

The transient operation of a new multiwavelength pyrometer based on a dispersing prism and a Si photodiode array is presented. After calibration, transient tests were performed using a tungsten strip lamp, supplied by a current pulse of 0.3-s duration. Measurements were carried out with a data acquisition system consisting of a FET multiplexer, a DVM (14 bit, 100 kHz), and a buffer memory (64 kbytes). Pyrometer signals are processed off-line, and temperature vs time is displayed. With the present arrangement, temperature measurements at 20 wavelengths may be performed with 200s resolution. Faster measurements are possible with a reduced number of channels.Paper presented at the Third Workshop on Subsecond Thermophysics, September 17–18, 1992, Graz, Austria.Deceased     

Characterisation of single-mode fibres by near-field measurement

A new technique for the determination of the refractive-index profile of single-mode optical fibres from a simple near-field measurement is proposed. This permits one to deduce accurately all the important parameters of the fibre.     

Oncogenes and antioncogenes involved in human thyroid carcinogenesis

Previous studies have shown that adult mice increase cold-induced heat production as a result of repeated exposures to cold, but that aged mice do not. The objective of the present study was to investigate changes in heat loss during repeated cold exposures in adult and aged C57BL/6J mice. Mice were partially restrained for three hours at 6 degrees C, three times at one-week intervals. Dry heat loss was inferred from measurements of differential temperature between the incoming and outgoing air in the experimental chamber. During the first cold exposure, aged mice showed less heat loss (both total and adjusted for body temperature) than adult animals, suggesting greater peripheral vasoconstriction in aged mice. With repeated cold exposures, both age groups showed increased heat loss, but the aged mice showed greater increase of heat loss, so that by the third cold stress test, no significant differences in heat loss between adult and aged mice were observed. The increase of heat loss after repeated cold exposures in aged mice might reflect a lesser peripheral vasoconstriction, serving to reduce the possibility of tissue necrosis in the cold.     

Finite difference methods for the analysis of integrated optical waveguides

A finite difference method based on a Crank-Nicolson discretisation procedure has been implemented and applied to the analysis of propagation of optical beams in dielectric waveguides. It is based on a new formula which takes into account the correct boundary conditions. Comparisons with the well known BPM technique show a definite improvement in computer time saving, accuracy and ease of use.<>     

Optical processing technique for spot-size measurements in single-mode fibres

A new, simple and very promising technique for spot-size measurements in single-mode fibres is proposed, based on a spatial filter which modulates the optical beam at the output of the fibre. Its inherent simplicity, accuracy and high efficiency make it attractive for laboratory and factory measurements.     

An evaluation of the Ektachem serum lithium method and comparison with flame emission spectrometry

We evaluated the performance of a new colorimetric method in dry chemistry for serum lithium (Li) assay using an Ektachem E500 analyser. Imprecision results were acceptable and the linearity was verified for concentrations within the range of 0.2-3.9 mmol l-1, i.e. y(measured) = 1.02x(calculated) + 0.07, r = 0.99. The Ektachem Li assay was unaffected by potassium (K), calcium (Ca) and magnesium (Mg) at all concentrations tested. Significant interference was caused by sodium (Na) and haemoglobin. Statistically and clinically significant interference was caused by high concentrations of Na (213 mmol l-1) with a bias of 0.20 mmol l-1 (p = 0.02) and by high levels of haemoglobin (280 mumol l-1) with a bias of 0.20 mmol l-1 (p = 0.01). Comparison of serum Li results from 80 patient samples assayed using the Ektachem method with those obtained using the IL943, a flame atomic emission spectrometry (FAES)-based method, gave a regression line equation: Ektachem = 0.95xFAES + 0.13, r = 0.96. The data revealed a mean difference of 0.10 mmol l-1 between the Ektachem and FAES results that was statistically significant (p = 0.01), but clinically negligible. We conclude that the Kodak method provides reliable Li serum results and represents a valid alternative to the FAES method.     

Probiotics in childhood

The Probiotics (Lactic acid bacteria) represent a nutritional live microbial supplement that positively affects host by enhancing the microbial balance. A survey is made of the most relevant studies concerning the use of probiotics in the prevention and treatment of infantile acute diarrhoea (by rotavirus or other agents), pseudomembranous colitis, hospital-acquired and antibiotic-associated diarrhoeas. Although the probiotics mechanism of action is not yet completely understood, it has been hypothesized that they exert an inhibitory effect on the intestinal inflammation by immune response modulation. Due to this property, the use of probiotics has therefore been suggested in other severe diseases such as chronic inflammatory bowel diseases, rheumatoid arthritis, food allergy, atopic dermatitis and as immunoadjuvant for oral vaccines.     

Electrical Characterization of a Superconducting Hot Spot Microbolometer

We report on fabrication and electrical noise measurements of an antenna coupled hot spot microbolometer operating in vacuum at liquid helium temperature. A noise equivalent power (NEP) of about 40 fW/Hz^1/2 has been measured at the output of a home made transimpedance amplifier operating at room temperature. This result shows the feasibility of microbolometers for a THz-range camera with a simplified electronic readout scheme      

New method for mode-field radius measurements in single-mode fibres based on harmonics detection

A new, easily implementable technique for mode-field radius measurement is described. It is based on a dynamical filtering and the detection of two harmonics of the fibre output radiation. The results are presented and discussed.