Influence of device engineering on the analog and RF performances of SOI MOSFETs

This work presents a systematic comparative study of the influence of various process options on the analog and RF properties of fully depleted (FD) silicon-on-insulator (SOI), partially depleted (PD) SOI, and bulk MOSFET's with gate lengths down to 0.08 /spl mu/m. We introduce the transconductance-over-drain current ratio and Early voltage as key figures of merits for the analog MOS performance and the gain and the transition and maximum frequencies for RF performances and link them to device engineering. Specifically, we investigate the effects of HALO implantation in FD, PD, and bulk devices, of film thickness in FD, of substrate doping in SOI, and of nonstandard channel engineering (i.e., asymmetric Graded-channel MOSFETs and gate-body contacted DTMOS).     

Advanced architecture for a one-chip 16×16 digital switch

A one-chip 16×16 digital switch (SWEL) is presented which is designed for use in a wide variety of applications, ranging from digital mobile radio and satellite applications, to PCM switching systems (integrated services digital network). It provides a compact, low-power solution to perform in channel-controlled switching of 64-kb/s or 2-Mb/s channels. Both architecture and design issues are discussed in detail; a 1.2 μm double metal CMOS technology was employed in the design. The multiplexed architecture allows for easy implementation of new application-specific requirements, making this circuit the cornerstone for new telecommunication switching products     

Small-dose hyperbaric versus plain bupivacaine during spinal anesthesia for cesarean section

In a double-blind, randomized trial, 98 parturients undergoing cesarean section received either hyperbaric or plain bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural procedure. To prevent hypotension, 1000 mL of lactated Ringer's solution, 500 mL of hydroxyethyl starch 6%, and ephedrine 5 mg were administered i.v. The height of the block was equal in both groups, but more patients in the plain group had blocks that were either too high or too low (P < 0.01). The number of patients requiring epidural supplementation was equal in both groups. Strict criteria were used to treat hypotension. The overall incidence of systolic blood pressure (<90 mm Hg) was 13%, whereas it was more pronounced in the plain group (21% vs 6% in the hyperbaric group, P < 0.05), which required more ephedrine (P < 0.05) and in which a greater incidence of nausea was noticed (P < 0.05). We conclude that the use of a small dose of intrathecal bupivacaine combined with sufentanil plus our described preloading regimen resulted in a lower incidence of hypotension. Further, we conclude that the use of hyperbaric bupivacaine in this manner provides a more reliable block and a lower incidence of hypotension than plain bupivacaine. Implications: A small dose of hyperbaric bupivacaine 0.5% combined with sufentanil used intrathecally during cesarean section offered a more reliable cephalad spread of the spinal block than the glucose-free combination, which was reflected in a lower incidence of hypotension and nausea.     

Recent developments in fluorescence—based mincroscopy applied in biomedical sciences

1.IntroductionOverthelastfourdecades,fluorescencemicroscopyhasexperiencedatremendousinnovat-ingevolutionandisnowadaysawellestablishedtechniqueinmanyareasofbiomedicalre-search.Inaddition,fluorescencemicroscopicalimaginghasprovenanessentialtoolforstudy-ingbothcellstructureanddynamicprocessestakingplacewithinonecellorbetweenneigh-bouringcells.Thepresentshortreviewwillfocusonthemostrecentdevelopmentsinthisfieldofmicroscopy.2.ConventionalfluorescencemicroscopyTheterm“fluorescence”denotestheprope…     

Metal-assisted secondary ion mass spectrometry: influence of Ag and Au deposition on molecular ion yields

A series of organic dyes and a pharmaceutical are used to study secondary ion yield enhancement by metal deposition. The molecules were dissolved in methanol and spin-casted on silicon substrates. Subsequently, silver or gold was evaporated onto the samples to produce a very thin coating. The coated samples, when measured with TOF-SIMS, showed a considerable increase in characteristic secondary ion intensity. Gold evaporated samples appeared to exhibit the highest signal enhancement. A major advantage of the metallization technique is that it can be used on real world samples. In particular, additive containing organic crystals could be studied; however, the observed signal increase does not occur at any given moment. The time between metal deposition on the sample surface and the measurement of the sample with TOf-SIMS appears to have an important influence on the enhancement of the secondary ion intensities. Therefore, the metal-coated samples were measured at different times after sample preparation. The results show that, depending on the sample and the metal deposited, the secondary ion signals reach their maximum at different times. Further study will be necessary to reveal the mechanism responsible for the observed enhancement effect.     

Topographical distribution and immunocytochemical features of colonic neurons that project to the cranial mesenteric ganglion in the pig

Using the retrograde neuronal tracers Fast blue and Fluorogold, the topographical distribution and morphological features of porcine colonic neurons projecting to the cranial (superior) mesenteric ganglion have been investigated. Two to four weeks after injection of the tracer into the cranial mesenteric ganglion of immature pigs, labelled neurons were found throughout the colon. In the myenteric and outer submucous plexuses, they were present in ganglia situated to the side of the mesenteric attachment. The highest density of labelled neurons was observed at the end of the ascending colon, which in the pig represents 78-80% of the total colon length. The viscerofugal neurons had a multidendritic appearance and part of them were immunoreactive for calcitonin gene-related peptide or serotonin. This study has revealed similarities but also significant differences in the colono-sympathico-colonic pathways between the pig and small laboratory animals such as the guinea-pig.     

The application of ‘least-cost’ modelling as a functional landscape model

The growing awareness of the adverse effects of habitat fragmentation on natural systems has resulted in a rapidly increasing number of actions to reduce current fragmentation of natural systems as well as a growing demand for tools to predict and evaluate the effect of changes in the landscape on connectivity in the natural world. Recent studies used ‘least-cost’ modelling (available as a toolbox in GIS-systems) to calculate ‘effective distance’, a measure for distance modified with the cost to move between habitat patches based on detailed geographical information on the landscape as well as behavioural aspects of the organisms studied. We applied the method to a virtual landscape and a small scaled agricultural system subject to different scenarios in a land re-allotment project. We discuss the importance of technical aspects and ecological assumption underlying this modelling method. The model is shown to be a flexible tool to model functional connectivity in the study of the relation between landscape and mobility of organisms as well as in scenario building and evaluation in wild life protection projects and applied land management projects. Since ‘effective distance’ has the same units as Euclidean distance (m), this effective distance may be a straightforward way to include landscape and behavioural aspects in other models which include distance as a measure for isolation. We show the importance of the ‘ecological’ quality of the input maps and the choice of relevant landscape features and resistance values.     

SACHEM, a versatile DMT-based modem transceiver for ADSL

The complete digital processing (physical medium dependent) of the discrete multitone modulation scheme and transmission convergence layer has been integrated into a single device, processed in 0.35-μm standard CMOS process. Power and area are kept well within limits, making this device a cost effective solution for asymmetric digital subscriber line and network terminating systems. New design methods were used to meet the severe time-to-market constraint of this high-complexity device     

Inbreeding and divorce in blue and great tits

In blue tits, Parus caeruleus, and other wild birds, matings between close relatives or between genetically similar individuals are associated with fitness costs, often in terms of lower hatching success of the eggs. If individuals cannot assess their genetic similarity to potential mates, those fitness costs may be hard to avoid; however, they may use the proportion of unhatched eggs in their clutch as a cue for their mate choice in the next season. We tested this hypothesis using data from a long-term population study on blue and great tits, Parus major. Divorce in response to inbreeding depression can be considered a special case of the 'incompatibility hypothesis'. As predicted from this hypothesis, both male and female blue tits benefited from divorce when part of their clutch failed to hatch. There was no evidence however, that divorce in blue or great tits was related to the presence of unhatched eggs in the nest. Copyright 1998 The Association for the Study of Animal Behaviour     

25 to 300°C ultra-low-power voltage reference compatible withstandard SOI CMOS process

A new patented voltage reference is presented. The very simple architecture, which can be implemented in standard silicon-on-insulator CMOS processes, gives very low power consumption (from 1 pA at 25°C up to 50 nA at 300°C) and good voltage stability (about 200 ppm/°C) over the whole temperature range