A robust detector for multicarrier spread spectrum transmission over partially jammed channels

Multicarrier spread spectrum (MC-SS) is an alternative to the conventional spread spectrum (SS) techniques that behave significantly better when the system is subject to narrow- or partial-band interference. However, successful implementation of the optimum detector requires knowledge of noise and interference variance in each subcarrier band. We propose a suboptimal detector for MC-SS that keeps the significant gain of MC-SS over the conventional SS, with a relatively low loss compared with the optimum MC-SS detector. Theoretical analysis and computer simulations that corroborate the theory are presented.     

The problem and treatment of DC offsets in FDTD simulations

This paper discusses the causes of and some solutions to the commonly observed problem of DC field offsets in finite-difference time-domain (FDTD) simulations. DC electric and magnetic field offsets are shown to be valid calculated responses of the modeled systems, resulting from interaction between the turn-on characteristics of the source and the properties of the models. The DC offsets may be avoided in the time domain by tailoring the source waveforms or in the frequency domain by post-processing the FDTD output.     

The performance of a new biological water quality score system based on macroinvertebrates over a wide range of unpolluted running-water sites

The occurrence of families of macroinvertebrates has recently been used as the basis for the BMWP (Biological Monitoring Working Party) system of assigning scores to lotic sites. In this study the performance of the system across 268 sites on 41 rivers providing a wide range of physical and chemical features has been appraised. Changes in score and ASPT (average score per taxon) with respect to season and sampling effort have been examined. Seasonal variations were relatively slight and it is concluded that samples taken in any of the three seasons, spring, summer or autumn, were likely to provide consistent estimates of score and particularly ASPT. Sample replication led to substantial accretion of scores but had little effect on ASPT and therefore more information was obtained for less effort when ASPT was used. Data are presented on score and ASPT values for 8 groups of sites derived by multivariate classificatory techniques. Considerable variability in achievable score and ASPT was observed in the different groups of unpolluted sites. In general, scores were highest in the group at the middle of the range of environmental features and lowest in groups at the bottom of the range (lowland areas). ASPT in contrast showed a relatively steady decline in values between groups at the top (mainly upland rivers) and bottom of the range of environmental features. Attempts were made to predict score and ASPT from physical and chemical data, or physical data alone using multiple regression. Equations used to predict ASPT explained on average a higher proportion of the variance (65%) than those predicting scores (22%). It is suggested that predictive equations for ASPT will enable theoretical ASPT to be calculated, thus providing target values against which observed values can be compared. Recommendations to facilitate use and interpretation of the BMWP score system are presented.     

Lipid Metabolism Is Dysregulated before,during and after Pregnancy in a Mouse Model of Gestational Diabetes

The aim of the current study was to test the hypothesis that maternal lipid metabolism was modulated during normal pregnancy and that these modulations are altered in gestational diabetes mellitus (GDM). We tested this hypothesis using an established mouse model of diet-induced obesity with pregnancy-associated loss of glucose tolerance and a novel lipid analysis tool, Lipid Traffic Analysis, that uses the temporal distribution of lipids to identify differences in the control of lipid metabolism through a time course. Our results suggest that the start of pregnancy is associated with several changes in lipid metabolism, including fewer variables associated with de novo lipogenesis and fewer PUFA-containing lipids in the circulation. Several of the changes in lipid metabolism in healthy pregnancies were less apparent or occurred later in dams who developed GDM. Some changes in maternal lipid metabolism in the obese-GDM group were so late as to only occur as the control dams’ systems began to switch back towards the non-pregnant state. These results demonstrate that lipid metabolism is modulated in healthy pregnancy and the timing of these changes is altered in GDM pregnancies. These findings raise important questions about how lipid metabolism contributes to changes in metabolism during healthy pregnancies. Furthermore, as alterations in the lipidome are present before the loss of glucose tolerance, they could contribute to the development of GDM mechanistically.     

Phytochemical Composition of <Emphasis Type="Italic">Oryza sativa</Emphasis> (Rice) Bran Oil Bodies in Crude and Purified Isolates

We describe a procedure for isolating and purifying oil bodies (OBs) from Oryza sativa bran, and present evidence that strongly suggests a physical association between the OB organelles and several antioxidant phytochemicals (γ-oryzanol and several tocochromanols). This suggestion arises from work showing that despite comprehensive washing steps (9 M urea, water), the majority of the tocotrienols and tocopherols (77 and 73 %, respectively) and oryzanols (91 %) remain integral to the oil bodies, not being released unless the latter are sacrificed. This in turn provides a valuable comparison with similar analyses of tocochromanols in other plant species, as well as indicating that rice bran, normally a waste product from the rice industry, may provide a valuable source of antioxidants as well as protein and unsaturated fat.     

Prof. James R. Wait and mining production technology-anappreciation

Prof. James R. Wait (1951, 1953, 1967) examined electromagnetic (EM) wave propagation in many situations of interest to mining production, including propagation in tunnels, propagation along extended conductors such as cables and drill stems, and propagation in coal seams. This work remains relevant, both to the mining engineer interested in the EM environment of an operating mine and to the electrical engineer interested in verifying new computational techniques and in extending the scope of EM technology in mining production. Late work in EM focussing in a geological environment is relevant to “next generation” geophysical monitoring equipment     

Electromagnetic compatibility

The focus of this issue's column is teaching electromagnetic compatibility. A summary of resources for this topic is found in the article by Levent Sevgi, and additional online course materials are summarized on the IEEE AP-S education course material repository Web site: www.ece.utah.edu//spl sim/cfurse/APS/course.htm. The column also provides a set of suggestions that are applicable to a variety of courses on opportunities to teach oral presentation skills.     

Integration of signals/systems and electromagnetics courses through the design of a communication system for a cardiac pacemaker

The integration of multiple concepts and courses through laboratory design projects are part of a new experimental program at the University of Utah, supported by the National Science Foundation, the College of Engineering, and the University of Utah. One such project is the design of an FSK communication system for a cardiac pacemaker, which combines labs from the junior-level "signals and systems" courses and the junior-level electromagnetics course, which are both taught in the same semester. The electromagnetic and the signal and system labs are briefly described in this paper.