A 100-MIPS GaAs asynchronous microprocessor

The authors describe how they ported an asynchronous microprocessor previously implemented in CMOS to gallium arsenide, using a technology-independent asynchronous design technique. They introduce new circuits including a sense-amplifier, a completion detection circuit, and a general circuit structure for operators specified by production rules. The authors used and tested these circuits in a variety of designs

Low-Energy Asynchronous Memory Design

We introduce the concept of energy per operation as a measure of performance of an asynchronous circuit. We show how to model energy consumption based on the high-level language specification. This model is independent of voltage and timing considerations. We apply this model to memory design. We show first how to dimension a memory array, and how to break up this memory array into smaller arrays to minimize the energy per access. We then show how to use cache memory and pre-fetch mechanisms to further reduce energy per access

Wintering avifauna of Chaco and pantanal habitats in Bahí­a Negra (Northern Paraguay)

Se estudió la avifauna de hábitats típicos de dos ecorregiones, el Pantanal y el Chaco, en el norte de Paraguay (departamento de Alto Paraguay) mediante transectas y observaciones puntuales. Se detectaron 132 especies (109 en bosque y 75 en río), de las cuales 37 utilizaban además hábitats modificados. Las especies más abundantes fueron <i>Phalacrocorax olivaceus</i>, <i>Pitangus sulphuratus</i> y <i>Gnorimopsar chopi</i> en el río y <i>Agelaioides badius</i>, <i>Coryphospingus cucullatus</i> y <i>Sicalis luteola</i> en el bosque. Doce especies en el río y 11 en el bosque aparecieron en el 100% de los recorridos de las transectas, siendo 5 de ellas comunes a ambas zonas. Siete especies (6.4%) del bosque tuvieron un tamaño promedio de grupo de cinco o más individuos, mientras que en el río fueron seis (8%). En el bosque eran numerosas las bandadas mixtas de <i>Zonotrichia capensis</i>, <i>Sicalis luteola</i>, <i>Coryphospingus cucullatus</i>, <i>Paroaria coronata</i>, <i>Agelaioides badius</i> y <i>Molothrus bonariensis</i>. La diversidad de especies observada fue de 80.4 en el bosque y de 58.1 en el río.The avifauna of habitats typical of two ecoregions in northern Paraguay (Alto Paraguay Department), Chaco and Pantanal, was studied through transects and opportunistic observations. Of 132 species recorded, 109 were in the forest, 75 in the river, and 37 in disturbed habitats. The most common species were <i>Phalacrocorax olivaceus, Pitangus sulphuratus</i> and <i>Gnorimopsar chopi</i> in the river, and <i>Agelaioides badius, Coryphospingus cucullatus</i> and <i>Sicalis luteola</i> in the forest. Twelve species of river habitats and 11 species of forest habitats were recorded in all samplings, five of them common to both zones. Seven species (6.4%) of the forest and six (8%) of the river averaged a flock size of five or more individuals. In the forest, flocks were numerous and composed primarily of <i>Zonotrichia capensis, Sicalis luteola, Coryphospingus cucullatus, Paroaria coronata, Agelaioides badius</i> and <i>Molothrus bonariensis</i>. Species diversity was 80.4 in the forest and 58.1 in the river

High density InAlAs/GaAlAs quantum dots for non-linear optics in microcavities

Structural and optical properties of InAlAs/GaAlAs quantum dots grown by molecular beam epitaxy are studied using transmission electron microscopy, temperature- and time resolvedphotoluminescence. The control of the recombination lifetime (50 ps – 1.25 ns), and of the dot density (5.10−8 – 2.1011 cm−3) strongly suggest that these material systems can find wide applications in opto-electronic devices as focusing non linear dispersive materials as well as fast saturable absorbers