Architectural power analysis: The dual bit type method

This paper describes a novel strategy for generating accurate black-box models of datapath power consumption at the architecture level. This is achieved by recognizing that power consumption in digital circuits is affected by activity, as well as physical capacitance. Since existing strategies characterize modules for purely random inputs, they fail to account for the effect of signal statistics on switching activity. The dual bit type (DBT) model, however, accounts not only for the random activity of the least significant bits (LSB's), but also for the correlated activity of the most significant bits (MSB's), which contain two's-complement sign information. The resulting model is parameterizable in terms of complexity factors such as word length and can be applied to a wide variety of modules ranging from adders, shifters, and multipliers to register files and memories. Since the model operates at the register transfer level (RTL), it is orders of magnitude faster than gate- or circuit-level tools, but while other architecture-level techniques often err by 50-100% or more, the DBT method offers error rates on the order of 10-15%     

An improved system for the control of dissolved oxygen in freshwater aquaria

A system for the removal and control of dissolved oxygen (DO) from freshwater was designed and constructed with aquarium-type fish studies in mind. Degassed water was obtained using a partial vacuum of -14 psi, and DO regulated at an aquarium scale using electronically controlled aeration with timed partial water renewal. The degassing system was capable of producing water with approximately 1.7 mg L(-1) DO within 10 min of operation, and 0.55 mg L(-1) after 2h. The control system was capable of maintaining DO levels of ca 0.8 mg L(-1) over 48 h in the absence of aeration and further capable of precisely controlling DO levels as low as 1.16+/-0.002 mg L(-1) (mean+/-SEM) with aeration over a 48 h period.     

Application of flow cytometry for examining phytoplankton succession in two eutrophic lakes

Flow cytometry has potential as a rapid assessment technique to evaluate phytoplankton biomass and species composition. It facilitates for multi-parameter analysis of individual cells on the basis of light scattering effects induced from cellular constituents, as well as auto-fluorescence. Fluorescence emission characteristics may be especially useful in classifying cyanobacteria as they contain phycoerythrin which emits light predominantly in the 550-600 nm waveband, chlorophyll-a (650-700 nm emission) and allophycocyanin (660 nm emission). The objective of our study was to assess the utility of flow cytometry for the rapid identification and sorting of freshwater algae and cyanobacteria species. Using a selection of laboratory-cultured freshwater algae and cyanobacteria species, this study demonstrated unique light scatter and fluorescent characteristics for each species examined, allowing for rapid species identification and sorting of mixed populations of laboratory cultures and samples from two lakes in the Rotorua region (New Zealand). Analysis of lake water samples collected over seven months demonstrated changes in abundance and community composition of phytoplankton in the two lakes and demonstrates that flow cytometry may be a useful technique for examining seasonal changes in phytoplankton composition.     

Functional Peptide Monolayers at Interfaces

Amphiphilic peptides can be designed to form ordered supramolecular structures at hydrophilic-hydrophobic interfaces. These systems rely on the ability of peptides to fold into certain secondary structures at interfaces. This review focuses on the design of amphiphilic β-sheet peptide assemblies in monolayers at interfaces, and their relevance to inducing mineralization and interactions with specific ions. In addition, the review discusses recent studies demonstrating the applicability of designed amphiphilic β-sheet peptides to detection of specific small molecules and to elucidating intermolecular interactions relevant to drug delivery and enzyme catalysis systems.     

Vapor growth of CdSe:Cr and CdS:Cr single crystals for mid-infrared lasers

Single crystals of CdSe:Cr and CdS:Cr with the doping level up to 10¹⁹ cm⁻³ were grown by a vapor phase contact-free technique. An efficient room-temperature pulsed and continuous wave (CW) lasing with the CdSe:Cr crystal was achieved. First a pulsed lasing with the CdS:Cr crystal was also demonstrated. The slope efficiency on the absorbed energy was as high as 46.5% for Cr²⁺:CdSe and 39% for Cr²⁺:CdS lasers. Using an intra-cavity prism, the Cr²⁺:CdSe laser wavelength was continuously tuned from 2.26 to 3.61 μm while the Cr²⁺:CdS laser from 2.2 to 3.3 μm. For the laser wavelength, the crystal passive loss coefficient was estimated to be smaller than 0.045 cm⁻¹ for CdSe:Cr crystals and 0.039 cm⁻¹ for CdS:Cr crystals. For the Cr²⁺:CdSe laser, the CW output power up to 1.07 W was achieved.     

Efficient CO2laser modulation internal to the cavity by methyl chloride gas

Modulation of a CO2laser with a Stark cell internal to the cavity has been achieved with very low voltage and capacitance requirements-100 V/cm for 50 percent modulation and 50 percent absorptions with a capacitance of the order of 10 pF.     

Is it safer behind the gates? Crime and gated communities in South Africa

Gated communities have long been seen as a rational response to rising crime levels, yet very little is known about the extent to which residing in a gated community actually reduces an individuals’ risk of criminal victimisation. In this study, we use location quotients to compare the extent of burglary in gated communities with burglary across the entire city of Tshwane, South Africa, as well as compare burglary in gated communities with burglary occurring within a series of buffer intervals immediately surrounding these communities. Finally, we identify what physical characteristics of gated communities differentiate between high and low burglary in these enclaves. Prior to expectations, we found that gated communities (and their immediate surrounding areas) are associated with increased levels of burglary. There are, however, a number of physical characteristics of gated communities which are associated with much lower burglary levels. The implications of our work from a crime prevention and development planning perspective are discussed.     

Tensions in setting health care priorities for South Africa''s children

Intractable detrusor overactivity can result in considerable morbidity and, in the case of neurogenic bladder dysfunction, can put the upper tracts at risk. Once conservative treatments have been exhausted the aim of surgery is to increase functional bladder capacity and decrease the maximal detrusor pressure at this capacity. The mainstay of contemporary therapy has been augmentation cystoplasty; the different techniques and recent literature are reviewed herein. Bladder autoaugmentation is compared and contrasted with augmentation cystoplasty and its role is discussed, as is the less invasive technique of sacral neuromodulation with reference to their role within the range of surgical treatments for detrusor activity.