56 research outputs found

    A sub-1 V, 26 μw, low-output-impedance CMOS bandgap reference with a low dropout or source follower mode

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    We present a low-power bandgap reference (BGR), functional from sub-1 V to 5 V supply voltage with either a low dropout (LDO) regulator or source follower (SF) output stage, denoted as the LDO or SF mode, in a 0.5-μm standard digital CMOS process with V tn≈ 0.6 V and |V tp| ≈ 0.7 V at 27 °C. Both modes operate at sub-1 V under zero load with a power consumption of around 26 μW. At 1 V (1.1 V) supply, the LDO (SF) mode provides an output current up to 1.1 mA (0.35 mA), a load regulation of ±8.5 mV/mA (±33 mV/mA) with approximately 10 μ s transient, a line regulation of ±4.2 mV/V (±50μV/V), and a temperature compensated reference voltage of 0.228 V (0.235 V) with a temperature coefficient around 34 ppm/° C from -20°C to 120 °C. At 1.5 V supply, the LDO (SF) mode can further drive up to 9.6 mA (3.2 mA) before the reference voltage falls to 90% of its nominal value. Such low-supply-voltage and high-current-driving BGR in standard digital CMOS processes is highly useful in portable and switching applications. © 2010 IEEE.published_or_final_versio

    Co-simulation of RFIC with bondwire antenna via retarded PEEC method

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    We present an antenna modeling method based on partial element equivalent circuit (PEEC) theory. The antenna is modeled as an equivalent circuit of lumped circuit elements, which enables circuit co-simulation between the antenna and circuits in both time and frequency domains. Antenna radiation is captured as an equivalent radiation resistor. For verification, a 2.4-GHz transmitter with bondwire antenna was implemented in a standard digital 0.35μm CMOS technology. Measurement shows good agreement with the proposed model. This model can be applied to any other on-chip electromagnetic structures. © 2012 IEEE.published_or_final_versio

    Maggot debridement therapy in chronic wound care

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    Objective: To review the current evidence on the mechanism of actions and clinical applications of maggot debridement therapy. Data sources: Literature search of PubMed and Medline was performed up to January 2007. Study selection: Original and major review articles related to maggot debridement therapy were reviewed. Key words used in the literature search were 'maggot debridement therapy', 'wound healing', and 'chronic wound management'. Data extraction: All relevant English and Chinese articles. Data synthesis: The mechanism of such maggot therapy was shown to be due to the debridement, disinfection, and wound healing enhancement actions of maggot excretions/secretions. The efficacy of maggot debridement therapy in chronic wound management has been demonstrated in chronic venous ulcers, pressure ulcers, and diabetic ulcers. There is also a new delivery system for the excretions/secretions, which has been shown to be as effective as using live maggots. Conclusions: Maggot debridement therapy has been shown to be a safe and effective means of chronic wound management. However, there are a number of limitations when considering its local applicability. Future development of the delivery system may help to overcome some of these limitations and improve its acceptability.published_or_final_versio

    Recent Advances in Animal and Human Pluripotent Stem Cell Modeling of Cardiac Laminopathy

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    Modeling Treatment Response for Lamin A/C Related Dilated Cardiomyopathy in Human Induced Pluripotent Stem Cells.

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    Attenuation of Hind-limb Ischemia in Mice with Endothelial-like Cells Derived from Different Sources of Human Stem Cells

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    Efficient attenuation of Friedreich's ataxia (FRDA) cardiomyopathy by modulation of iron homeostasis-human induced pluripotent stem cell (hiPSC) as a drug screening platform for FRDA

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    Friedreich’s ataxia (FRDA), a recessive neurodegenerative disorder commonly associated with hypertrophic cardiomyopathy, is caused by silencing of the frataxin (FXN) gene encoding the mitochondrial protein involved in iron-sulfur cluster biosynthesis. We aimed to utilize our previously established FRDA human induced pluripotent stem cell (hiPSC) derived cardiomyocytes model as a platform to assess the efficacy of treatment with either the antioxidant coenzyme Q10 analog, idebenone (IDE) or the iron chelator, deferiprone (DFP), which are both under clinical trial. In fact, DFP was able to more significantly suppress synthesis of reactive oxygen species (ROS) than IDE at the dosages of 10 nM and 25 μM respectively which agreed with the reduced rate of intracellular accumulation of iron by DFP treatment from 25 to 50 µM. With regard to cardiac electrical-contraction (EC) coupling function, decay velocity of calcium handling kinetics in FRDA-hiPSC-cardiomyocytes was significantly improved by DFP treatment but not by IDE. Further mechanistic studies revealed DFP also modulated iron induced mitochondrial stress as reflected by mitochondria network disorganization and decline in level of respiratory chain protein. In addition, iron-response protein (IRP-1) regulatory loop was overridden by DFP as reflected by the attenuated transferrin receptor (TSFR) suppression thereby reducing further iron uptake.published_or_final_versio

    Luminescence Dating in Fluvial Settings: Overcoming the Challenge of Partial Bleaching

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    Optically stimulated luminescence (OSL) dating is a versatile technique that utilises the two most ubiquitous minerals on Earth (quartz or K-feldspar) for constraining the timing of sediment deposition. It has provided accurate ages in agreement with independent age control in many fluvial settings, but is often characterised by partial bleaching of individual grains. Partial bleaching can occur where sunlight exposure is limited and so only a portion of the grains in the sample was exposed to sunlight prior to burial, especially in sediment-laden, turbulent or deep water columns. OSL analysis on multiple grains can provide accurate ages for partially bleached sediments where the OSL signal intensity is dominated by a single brighter grain, but will overestimate the age where the OSL signal intensity is equally as bright (often typical of K-feldspar) or as dim (sometimes typical of quartz). In such settings, it is important to identify partial bleaching and the minimum dose population, preferably by analysing single grains, and applying the appropriate statistical age model to the dose population obtained for each sample. To determine accurate OSL ages using these age models, it is important to quantify the amount of scatter (or overdispersion) in the well-bleached part of the partially bleached dose distribution, which can vary between sediment samples depending upon the bedrock sources and transport histories of grains. Here, we discuss how the effects of partial bleaching can be easily identified and overcome to determine accurate ages. This discussion will therefore focus entirely on the burial dose determination for OSL dating, rather than the dose-rate, as only the burial doses are impacted by the effects of partial bleaching
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