A single-chip 12.7 Mchips/s digital IF BPSK direct sequencespread-spectrum transceiver in 1.2 μm CMOS

This paper describes a fully integrated digital-spread spectrum transceiver chip fabricated through MOSIS in 1.2 μm CMOS. It includes a baseband spread spectrum transmitter and a coherent intermediate frequency (IF) receiver consisting of a Costas loop, an acquisition loop for the pseudo-noise (PN) sequence, and a clock recovery loop with a 406.4 MHz onchip numerically controlled oscillator (NCO). The transceiver is capable of operating at a maximum IF sampling rate of 50.8 MS/s and a maximum chip rate of 12.7 R Mchips/s (Mcps) with selectable data rates of 100, 200, 400, and 800 kbps. At the maximum operating speed of 50.8 R MS/s, it dissipates 1.1 W. In an additive white Gaussian noise channel the IF receiver achieves a receiver output SNR within 1 dB of theory and can acquire code with a wide range of input SNR from -17 dB to over 30 dB. The transceiver chip has been interfaced to an RF up/down converter to demonstrate a wireless voice/data/video link operating in the 902-928 MHz band     

Analysis of integrated optical waveguide mirrors

A new method is presented to analyze reflection losses of integrated mirrors, taking into account the exact guided mode profile and assuming that this profile remains unchanged up to the reflecting plane. The fraction of the reflected light coupled to one of the guided modes of the output waveguide is calculated, taking into account the mirror reflection coefficient. The influence of both translation and tilt of the reflecting plane is investigated. The method applies for every guided mode and any reflection angles. Numerical calculations are derived for a 90° optical corner mirror     

Intracavitary afterloading therapy as a new technique of boost irradiation in anal canal carcinoma

PURPOSE: There are different techniques of boost irradiation in the treatment of patients with anal carcinoma. A new system of applicators is presented, which can be used for an intracavitary afterloading therapy. MATERIAL AND METHODS: Three different applicators are available, the first with a central catheter (K1), a second with 5 semicircular fixed catheters (K2) and an eccentric shield, a third with 8 circular fixed catheters and a central shield (K3). RESULTS: The adequate choice of applicator and catheters takes into consideration the individual localisation and extension of anal carcinoma in planning therapy. Thus, in circular growing tumors, an irradiation of the whole circumference of the anal canal is possible. In non-circular growing tumors, the dose applied in the non-affected part of the anal canal can be reduced to a quarter of the dose applied at the tumor. CONCLUSION: The new system of intracavitary afterloading therapy is a good alternative to previous techniques of boost irradiation in the treatment of anal carcinoma. By means of this technique, irradiation can be highly individualized, the tumor better included and non-affected sections of the anal canal saved.     

NMR IMAGING, CALORIMETRIC, and MATHEMATICAL MODELING STUDIES of FOOD FREEZING

Nuclear magnetic resonance imaging (MRI), calorimetry, and temperature measurements were used to monitor cylindrical potato sections frozen at -11C and -42C. MRI showed the advance of the nonsymmetric freezing zone and loss of signal intensity as liquid water turned to ice. Differential calorimetry was used to follow heat removal during transient freezing. Measured times to 95% enthalpy change were 24 min (-42C) and 49 min (-11C), as compared to modeled values of 29 min (-42C) and 100 min (-11C). Times to 95% change in the NMR signal, integrated over the area of the image, were 21 min (-42C) and 56 min (-11C). Changes in NMR signal intensity could be correlated with the amount of unfrozen water remaining after a steady-state had been reached. At -42C, NMR indicated 25% unfrozen water remaining as compared to 26% by calorimetry, and 22% by modeling. At -11C, NMR measured 67% unfrozen water remaining as compared to 48% by calorimetry, and 25% by equilibrium modeling.     

SHELF-LIFE MODELING OF SWEETENED CONDENSED MILK BASED ON KINETICS OF MAILLARD BROWNING

Nonenzymatic browning and related changes were monitored in commercial sweetened condensed milk stored at 7, 15, 30, 45 and 55C. Darkening of the color measured in terms of absorbance (100 - reflectance percent) followed zero-order kinetics, the apparent activation energy (E_a) being 45.2 kJ/mol at 7–30C and 139.9 kJ/mol at > 30–55C. Hydroxy-methyl-furfural (HMF) showed a first-order increase, the associated E_a values being smaller than those for absorbance. The pH exhibited a linear decline after a small initial rise at 30C and below. As browning progressed, the coffee whitening ability of the product decreased along zero-order kinetics. The Q₁₀ values for these variables ranged from 1.21 to 1.84 for temperatures up to 30C and were nearly 2–3 times higher above 30C. The sensory color score was negatively correlated with absorbance. The linear regression of color score on absorbance and the temperature dependence of the latter as expressed by Arrhenius relationship were combined into a mathematical model which could be useful in predicting the product's shelf-life.     

Experimental determination of thermal conductivity of apple and potato at different moisture contents

Thermal conductivity of apple and potato samples was measured by means of a specifically designed apparatus based on Fitch's method. The thermal conductivity was determined at various moisture contents at the sample mean temperature of 30 °C. As expected the conductivity decreases with the decrease in moisture content. Thermal conductivity data were correlated with moisture content using a straight line.     

Accuracy of patient recall of opportunistic smoking cessation advice in general practice

OBJECTIVE: To determine the accuracy of patient recall of a question about smoking in a specified consultation in general practice; the accuracy of smokers' recall of advice to stop smoking; and predictors of accurate recall. DESIGN: Analysis of 1075 audiotapes was compared blind with matching patient questionnaires administered after the consultation to calculate sensitivity and specificity for patient recall as a dichotomous variable. Predictors of recall were determined by logistic regression. SETTING: General practitioner training practices, New South Wales, Australia. SUBJECTS: Thirty-four trainees and consecutive samples of their patients 16-65 years of age. RESULTS: Patient recall of a question about smoking had a high false positive rate of 21% but a sensitivity of 93%. Smokers over-reported advice to stop smoking (specificity 82%; sensitivity 92%). Predictors of accuracy of a question about smoking included patient sex (women 1.58 times more likely than men to be accurate); smoking status (smokers 1.7 times as likely as non-smokers to be accurate); and interval since consultation (those who completed their questionnaires within a week were 1.84 times more likely to be accurate). CONCLUSIONS: Patient recall is systematically biased towards over-reporting of a question about smoking status and, among smokers, of advice to quit. Although we recommend its continued application in health services evaluation, findings should be interpreted with caution, particularly if subjects are male or the interval between recall of smoking cessation advice and the occasion of service in which it might have occurred is considerably delayed.


     

Detecting delaminations in a composite beam using anti-optimization

The present study proposes a detection technique for delaminations in a laminated beam. The proposed technique optimizes the spatial distribution of harmonic excitation so as to magnify the difference in response between the delaminated and intact beam. The technique is evaluated by numerical simulation of two-layered aluminum beams. Effects of measurement and geometric noise are included in the analysis. A finite element model for a delaminated composite, based on a layer-wise laminated plate theory is used in conjunction with a step function to simulate delaminations