Automatic quantification of changes in bone in serial MR images of joints

Recent innovations in drug therapies have made it highly desirable to obtain sensitive biomarkers of disease progression that can be used to quantify the performance of candidate disease modifying drugs. In order to measure potential image-based biomarkers of disease progression in an experimental model of rheumatoid arthritis (RA), we present two different methods to automatically quantify changes in a bone in in-vivo serial magnetic resonance (MR) images from the model. Both methods are based on rigid and nonrigid image registration to perform the analysis. The first method uses segmentation propagation to delineate a bone from the serial MR images giving a global measure of temporal changes in bone volume. The second method uses rigid body registration to determine intensity change within a bone, and then maps these into a reference coordinate system using nonrigid registration. This gives a local measure of temporal changes in bone lesion volume. We detected significant temporal changes in local bone lesion volume in five out of eight identified candidate bone lesion regions, and significant difference in local bone lesion volume between male and female subjects in three out of eight candidate bone lesion regions. But the global bone volume was found to be fluctuating over time. Finally, we compare our findings with histology of the subjects and the manual segmentation of bone lesions.     

Application of Gate Turn-Off Thyristors in 460-V 7.5-250-hp AC Motor Drives

A 7.5-250-hp range of variable-frequency ac motor drives has been under development at the Westinghouse R & D Center since early in 1981. Design and performance details for prototype equipment rated for 10, 20, and 50 hp will be discussed. The drive system comprises a three-phase thyristor controlled ac/dc converter in conjunction with a dc/ac adjustable-frequency inverter using gate turn-off thyristors (GTO's). The output of the inverter is a six-step voltage wave in the range of 6-120 Hz, suitable for driving three-phase ac induction or synchronous motors. Details of the inverter design, including means to protect the gate turn-off thyristors from output line-to-line or line-to-ground short circuits, will be given special attention.     

Engine autoignition: The relationship between octane numbers and autoignition delay times

The research octane (RON) and motor octane (MON) numbers, carefully measured in standardized tests, are the principal parameters for characterizing autoignition of gasoline in engines. Increasingly, engines operate under different conditions of temperature, pressure, and mixture strength from those in these tests. As a result, RON and MON values become an incomplete guide to the onset of knock, and the octane index (OI), an octane number under operational conditions, is often measured. Values of the OI were measured with different fuels in a controlled autoignition single-cylinder engine, at different initial temperatures and pressures, at the instant of 10% heat release. Fundamental understanding of engine autoignition was sought by finding the OIs of different non-primary reference fuels (non-PRFs) by identifying the corresponding PRFs that give 10% heat release under identical conditions. The autoignition delay times of the PRFs were obtained from the shock tube data, for different temperatures and pressures, of the Aachen group. It was sufficiently accurate to equate the delay time of a non-PRF to that of the corresponding PRF under the same conditions for 10% heat release. The PRFs exhibited a higher value of the inverse pressure exponent for the delay time than the non-PRFs. Together with different temperature dependencies, these gave autoignition delay times of non-PRFs that could be higher than those of their associated RONs. This tendency increased with pressure and decreased with temperature and was most marked with olefenic and toluenic fuels. This could result in values of the OI that were higher than the RON of the fuel. This is important because, for a number of evolutionary reasons, engine pressures are tending to increase and temperatures to decrease.     

Synthesis,characterisation and use of 2-tetradecylcyclobutanone together with other cyclobutanones as markers for irradiated liquid whole egg

The synthesis and characterisation of 2-tetradecylcyclobutanone (TCB) is described. Both 2-dodecykyclobutanone and TCB were shown to be present in liquid whole egg irradiated at doses of 2.5 and 10.0 kGy. These compounds were absent from the unirradiated pasteurised samples. Using gas chromatography and infrared spectroscopy, there was also evidence for the presence in irradiated egg of 2-tetradeccnyl- and 2-tetradecadienylyclobutanone which are formed from oleic and linoleic acids, respectively. Authentic standards for these unsaturated cyclobutanones were not available commercially but the presence of 2-tetra-decenylcyclobutanone was substantiated by hydrogenating the egg extracts so converting this unsaturated cyclobutanone to TCB. Saturated and unsaturated cyclobutanones appear to be specific products of irradiation and are potential markers for detection of irradiated liquid egg and probably other fat-containing foods.     

The effect of size of sub-sample on mineral analysis values of apple fruits

Apple fruits were divided into opposite sectors of different sizes, and the mineral analyses of the sectors were compared with whole fruit values. Opposite sectors as small 8-12% of whole fruit weight were found to be as representative as larger sectors. There was no evidence of either a constant or a proportional bias arising as a result of sub-sampling. Sub-sampling variation was greater for Ca than for N, P, K and Mg.     

Band-tunable and multiplexed integrated circuits for simultaneous recording and stimulation with microelectrode arrays

Two thin-film microelectrode arrays with integrated circuitry have been developed for extracellular neural recording in behaving animals. An eight-site probe for simultaneous neural recording and stimulation has been designed that includes on-chip amplifiers that can be individually bypassed, allowing direct access to the iridium sites for electrical stimulation. The on-probe amplifiers have a gain of 38.9 dB, an upper-cutoff frequency of 9.9 kHz, and an input-referred noise of 9.2 microV rms integrated from 100 Hz to 10 kHz. The low-frequency cutoff of the amplifier is tunable to allow the recording of field potentials and minimize stimulus artifact. The amplifier consumes 68 microW from +/- 1.5 V supplies and occupies 0.177 mm2 in 3 microm features. In vivo recordings have shown that the preamplifiers can record single-unit activity 1 ms after the onset of stimulation on sites as close as 20 microm to the stimulating electrode. A second neural recording array has been developed which multiplexes 32 neural signals onto four output data leads. Providing gain on this array eliminates the need for bulky headmounted circuitry and reduces motion artifacts. The time-division multiplexing circuitry has crosstalk between consecutive channels of less than 6% at a sample rate of 20 kHz per channel. Amplified, time-division-multiplexed multichannel neural recording allows the large-scale recording of neuronal activity in freely behaving small animals with minimum number of interconnect leads.     

New Decision Support Tool for Treatment Intensity Choice in Childhood Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL), the most common cancer in childhood, has its treatment modulated by the risk of relapse. An appropriate estimation of this risk is the most important factor for the definition of treatment strategy. In this paper, we build up a new decision support tool to improve treatment intensity choice in childhood ALL. Our procedure was applied to a significant cohort of Brazilian children with ALL, the majority of the cases treated in the last decade in the two main University Hospitals of Rio de Janeiro. Some intrinsically difficulties of this dataset introduce an assortment of challenges, among those the need of a proper selection of features, clinical and laboratorial data. We apply a mutual information-based methodology for this purpose and a Neural Network to estimate the risk. Among the relapsed patients, 98.2% would have been identified as high-risk by the proposed methodology. The proposed procedure showed significantly better results when compared to the BFM95, a widely used classification protocol.