Combining microcontroller units and PLDs for best system design

Microcontroller timer units and programmable logic devices both can create complex system timing functions. Using the Motorola time processor unit available on the MC68332 and MC68HC1GY1 microcontrollers and PLDs from Altera, we compared the performance and flexibility of these devices in applications that require various timing functions. These investigations show that in certain systems the combination of a microcontroller timer and a PLD provides the most efficient design     

Complex-correlation radiometer

The correlation between the signals from the two antennas in a radio interferometer can be described by a complex correlation function. The real and imaginary parts of this function can be measured by a radiometer using two feedback loops to control four noise sources,B_{pr}(positive, real),B_{nr}(negative, real),B_{pi}(positive, imaginary), andB_{ni}(negative, imaginary). Theoretical analysis shows the system to be stable against amplifier gain fluctuations, and against moderate fluctuations in the phase shifts of the two amplification channels which are included in the system. Experimental verification is described in a following paper by Hubbard and Erickson [2].     

Luminescent quantum dot-bioconjugates in immunoassays, FRET, biosensing, and imaging applications

Colloidal semiconductor nanocrystals (quantum dots, QDs), such as CdSe-ZnS core-shell, are highly luminescent and stable inorganic fluorophores that represent a promising alternative to organic dyes for a variety of biotechnological applications. They show size-tunable narrow photoluminescence spectra spanning nearly the full visible region of the optical spectrum for QDs with CdSe cores. We have developed several approaches to conjugate either one type or a combination of biologically distinct proteins to CdSe-ZnS core-shell QDs rendered water-soluble by surface ligation with dihydrolipoic acid (DHLA) groups. QD-protein conjugates prepared using these approaches were found to exhibit high specificity and stability in immunoassays and in Förster resonance energy transfer (FRET) assays as well as in prototype QD bioconjugate sensors. Tunable QD emission over a wide range of wavelengths permitted effective tuning of the degree of energy overlap between the QD donor and an acceptor dye, allowing control over the rate of FRET. Additionally, we have used these QD-bioconjugates in live cell labeling. These hybrid bioinorganic conjugates represent a promising tool for use in many biotechnological applications.     

Distribution system grounding fundamentals

This article is an overview of the various relationships between neutral currents, ground currents, electrode impedances, and voltage potentials that are encountered in the operation of multi-grounded wye distribution systems. This system continuation is the most commonly used configuration among U.S. domestic utilities. Voltages range from 4.16/2.4 kV to 34.5/19.9 kV. The most common system voltages are 15- and 25-kV class systems with nominal operating voltages on rural systems generally being 12.47/7.2 kV and 24.9/14.4 kV. The article aims to review the relationships that might be encountered due to system grounding and provide an overview of common installations and their relative effectiveness.     

Size segregation and seasonal patterns in rusty crayfish Faxonius rusticus distribution and abundance on northern Lake Michigan spawning reefs

Non-native rusty crayfish are abundant egg predators on spawning reef habitats for lake trout and coregonines in northern Lake Michigan. To better understand rusty crayfish life-history on these unique habitats, we conducted monitoring in 2012 and 2013 at four locations previously identified as spawning areas for native fish. With the aid of a graphical causal model, we conducted an exploratory statistical analysis using a Bayesian multilevel modeling approach with model selection based on information criteria to identify important environmental variables for predicting rusty crayfish distribution and abundance on spawning reefs. We also compared seasonal trends in relative abundance, inferred from catch-per-unit-effort calculations from trapping, to previously reported accounts from a smaller inland lake. The results from our modeling provide evidence of size-class segregation across subtle changes in habitat characteristics of spawning reefs. Specifically, we found evidence that the distribution of >30 mm rusty crayfish was only weakly related to rock density (#/m²) relative to juveniles and smaller size classes. We also observed highest relative abundances from minnow trap monitoring in mid-October when water temperatures averaged 13.9 °C, which is later in the year and at cooler temperatures than similar monitoring from smaller inland lakes has reported. We hypothesize that unique environmental conditions elicit novel life-history responses from rusty crayfish on Lake Michigan spawning reefs and discuss our findings in the context of native fish restoration in the Laurentian Great Lakes.