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The carboxyl methyltransferase, which is claimed to exclusively methylate the carboxyl group of the C-terminal leucine residue of the catalytic subunit of protein phosphatase 2A (Leu(309)), was purified from porcine brain. On the basis of tryptic peptides, the cDNA encoding the human homologue was cloned. The cDNA of this gene encodes for a protein of 334 amino acids with a calculated M(r) of 38 305 and a predicted pI of 5.72. Database screening reveals the presence of this protein in diverse phyla. Sequence analysis shows that the novel methyltransferase is distinct from other known protein methyltransferases, sharing only sequence motifs supposedly involved in the binding of adenosylmethionine. The recombinant protein expressed in bacteria is soluble and the biophysical, catalytic, and immunological properties are indistinguishable from the native enzyme. The methylation of PP2A by the recombinant protein is restricted to Leu(309) of PP2A(C). No direct effects on phosphatase activity changes were observed upon methylation of the dimeric or trimeric forms of PP2A.

Low-power wearable sensing will soon allow the quantitative and continuous measurement of health parameters. In this paper we illustrate how wearable sensors can be used to track activity and energy expenditure, and measure stress. Soon such information may empower people in managing their own health, and provide the necessary data to enable a preventive approach to healthcare.

This paper presents a low-power switched-capacitor $Delta Sigma$ modulator for digital hearing-aid applications that features a novel summing successive approximation (SAR). The summing SAR performs multi-bit quantization together with the analog addition required in feed-forward (FF) $Delta Sigma$ modulator $(Delta Sigma {rm M})$ topologies, with no attenuation of the input signals and no need for amplifiers. The prototype is implemented in a 0.18-$mu$ m CMOS technology and its measurements demonstrate a dynamic range of 88 dB in 10 kHz bandwidth while consuming 155 $mu$W from a 1.8 V supply. The combined use of passive addition and SAR quantization reduces the complexity and power consumption of the modulator. The summing SAR ADC quantizer results in a calculated power saving of 40% when compared to a multi-bit FF $Delta Sigma$M using active addition and flash quantization.

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The paper presents a reconfigurable Delta-Sigma Modulator (¿SM) suitable for three operation modes, whose application ranges from bio-potential signal monitoring to hearing aids. A feed-forward 2nd-order SC ¿SM architecture with 4-bit quantizer is selected according to an analytic power optimization procedure. The ¿SM features programmable sampling capacitors in the first integrator and novel reconfigurable power-gated OTAs to adjust power consumption in each operation mode. An asynchronous embedded SAR converter implements low-power quantization and passive addition in the feed-forward topology. The prototype is implemented in a 0.18µm CMOS technology and operates from a supply voltage of 1V. Measurements show peak SNDRs from 99 to 75dB for signal bandwidths spanning from 256Hz to 16kHz, achieving figures of merit which are almost constant in the different modes, and range from 0.20 to 0.27pJ/c.s.

In this paper we present a low-power switched-capacitor In this paper we present a low-power switched-capacitor ¿S modulator for digital hearing-aid applications. The circuit adopts a novel summing successive approximation (SAR) block to perform multi-bit quantization together with the analog addition that is required in feed-forward topologies. The use of passive addition and SAR operation helps in reducing the complexity and power consumption of the modulator. The prototype is implemented in a 180 nm CMOS technology and measurements demonstrate 88 dB of dynamic range in a 10 kHz band while consuming 155µW from a 1.8V supply.

An important drawback of current biopotential monitoring systems is their dependence on gel electrodes, which can dry out, cause skin irritation, and necessitate skilled personnel. These associated drawbacks increase the running costs and significantly hamper their use in consumer healthcare and lifestyle applications. Unfortunately, the use of gel-free, or dry, electrodes increases the electrode-tissue contact impedance, thus exacerbating the effects of interference and cable motion artifacts. A solution is the use of active electrodes, i.e. electrodes in which an amplifier with high input impedance, low noise and good electrode offset rejection is co-integrated. Previous active electrodes employed voltage buffers to facilitate the inter-channel gain matching necessary to achieve high CMRR. However, low-noise buffers consume significant power and due to their lack of gain still require a low-noise and thus power-hungry back-end to keep the total integrated noise at acceptable levels. To reduce the total power dissipation, this paper proposes a biopotential monitoring system based on active electrodes with gain.

This paper presents a procedure for the power-optimal design of high-resolution low-bandwidth switched-capacitor (SC) ¿S modulators (¿SMs). The most power efficient ¿S architecture is identified among single-loop switched-capacitor (SC) feedback (FB) and feed-forward (FF) topologies with different loop order N, oversampling ratio OSR, and quantizer resolution B. Based on the results obtained, an experimental prototype is implemented in a 0.18µm CMOS process, achieving a signal-to-noise ratio (SNR) of 95 dB over a signal bandwidth fBW of 10 kHz. The prototype operates with a 1.28MHz sampling rate and dissipates a total power of 210uW from a 1.8V supply.

International audience; Self-assembly and self-alignment driven by capillary meniscus forces are presently at the core of many important technological applications, including solder bonding in flip-chip assembly and fluidic self-assembly for microelectronic packaging. Lateral capillary meniscus forces were object of substantial theoretical and numerical modeling in recent years. Anyway, these studies were unsatisfactorily supported by direct experimental investigations. In this paper we present a comprehensive study of lateral capillary forces of cylindrical menisci, where experimental, analytical and numerical analyses of the same physical system are compared. We describe the conceptually simple experimental apparatus we designed to investigate lateral forces arising from small perturbations of cilindrical liquid menisci. The apparatus allowed controlling all physical and geometrical parameters relevant to the experiments. We then reproduce our experimental data with a novel analytical model of lateral fluid meniscus forces and with finite element simulations. The remarkable agreement between our experiments and models, while confirming earlier reports, provides a solid foundation for all applications of lateral capillary forces. Moreover, our experimental apparatus may be used as testbed for further experimental investigations of confined fluid menisci.

The rapid evolution of electronic devices since the beginning of the nanoelectronics era has brought about exceptional computational power in an ever shrinking system footprint. This has enabled among others the wealth of nomadic battery powered wireless systems (smart phones, mp3 players, GPS, …) that society currently enjoys. Emerging integration technologies enabling even smaller volumes and the associated increased functional density may bring about a new revolution in systems targeting wearable healthcare, wellness, lifestyle and industrial monitoring applications.

We propose a new EEG-based wireless brain computer interface (BCI) with which subjects can “mind-type” text on a computer screen. The application is based on detecting P300 event-related potentials in EEG signals recorded on the scalp of the subject. The BCI uses a simple classifier which relies on a linear feature extraction approach. The accuracy of the presented system is comparable to the state-of-the-art for on-line P300 detection, but with the additional benefit that its much simpler design supports a power-efficient on-chip implementation. ispartof: pages:339-346 ispartof: Lecture Notes in Computer Science vol:5803 pages:339-346 ispartof: 32nd Annual Conference on Artificial Intelligence location:Paderborn, Germany date:15 Sep - 18 Sep 2009 status: published

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Phosphotyrosyl phosphatase activator (PTPA), a 37 kDa cytosolic protein that specifically activates the phosphotyrosyl phosphatase activity of the dimeric form of PP2A, was cloned from Drosophila melanogaster and Saccharomyces cerevisiae. Sequence alignment of PTPA from yeast to human revealed highly conserved regions including the type B fragment of the putative PTPA ATP binding site. We generated PTPA deletion mutants of these conserved regions as well as point mutations within regions that were suggested to be functionally important. The recombinant proteins were expressed in E. coli and subsequently purified. Activity measurements, linked with immunological detection, revealed that most of the well-conserved regions are essential for PTPA activity. However, neither the type A fragment of the putative ATP binding site nor the cysteine-rich region, present in all but the Drosophila and yeast homologues, appeared to be essential for PTPA activity. Moreover, we observed that PTPA truncated at glycine266 behaves as a dominant negative mutant since it is inhibitory to the wild-type PTPA.

We present an array of GaAs-based light-emitting diodes emitting at 850 nm, which is designed to be flip-chip joined on carriers like a silicon CMOS circuit. The light-emitting diodes are grown by MBE. After processing of the array and flip-chip joining using Indium-bumps, the substrate of the LED array is removed completely. Individual light-emitting diodes reach an external quantum efficiency of 3.3% after the complete process. ispartof: pages:10-15 ispartof: OPTOELECTRONIC INTERCONNECTS V vol:3288 pages:10-15 ispartof: Conference on Optoelectronic Interconnects V location:CA, SAN JOSE date:28 Jan - 29 Jan 1998 status: published

cDNA clones encoding the 65-kDa (PR65) and 55-kDa (PR55) regulatory subunits of protein phosphatase 2A from Xenopus laevis were isolated by homology screening with the corresponding human cDNAs, and used to analyze the developmental expression patterns of these genes. The PR65 subunit was found to be encoded by two genes, termed XPR65 alpha and XPR65 beta. The open reading frames of the alpha and beta cDNAs both span 1767 bp, and predict proteins of 64.4 kDa and 65.3 kDa, respectively, that are 87% identical. The predicted amino acid sequence of XPR65 alpha showed 95% and 84% identity with human PR65 alpha and PR65 beta proteins, respectively, whereas the identity of XPR65 beta with the same proteins was 87% and 86.5%, respectively. Only one type of Xenopus PR55 (XPR55) was isolated that showed 93% and 84% similarity to human PR55 alpha and PR55 beta, respectively. Analysis of the N-terminal region of XPR55 with the same regions of human PR55 alpha and PR55 beta, indicates that the XPR55 is the Xenopus homolog of the human PR55 alpha isoform. Despite the overall similarity with PR55 from other species, XPR55 has an N-terminal extention of at least 24 amino acids. In the ovary, a transcript of 2.8 kb, encoding the XPR65 beta, was predominantly expressed and these XPR65 beta mRNAs are present at a constant level during oogenesis until late embryogenesis. Expression of the 2.4-kb XPR65 alpha was low until the larval stage, then dramatically increased. In all adult tissues except ovary, the 2.4-kb alpha-specific mRNA was more abundant than the 2.8-kb beta transcript. Two transcripts of 2.4 kb and 2.5 kb, encoding the XPR55 subunit, were detected at a constant level throughout Xenopus oogenesis and during embryogenesis. Both transcripts were also expressed at similar levels in all adult tissues, but in a tissue-specific manner. Analysis of the XPR55 and XPR65 proteins using antibodies to recombinant proteins revealed that the overall levels of the two proteins were constant, in good agreement with mRNA data.

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