4,537 research outputs found

    GETTING THE MOST FOR OUR MONEY IN FARMLAND PRESERVATION

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    This paper looks at the design and operation of the main program in Maryland, the Maryland Agricultural Land Preservation Fund (MALPF). We examine the features of the program in comparison to possible alternative designs. Our broader purpose is to examine the nature of farmland preservation and the implications for how to best design farmland preservation programs.Agricultural and Food Policy,

    Energy Reduction Techniques to Increase Battery Life for Electronic Sensor Nodes

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    Preserving battery life in duty-cycled sensor nodes requires minimizing energy use in the active region. Lowering the power supply of CMOS gates down into sub-threshold mode is a good way to decrease energy. In this work, a unique technique to control the current in CMOS gates to reliably operate them in sub-threshold mode is described. Compared to the current state-of-theart for running digital gates in the sub-threshold regime, this work is often superior in its lack of complexity and in reduced variance in delay caused by process variations. In addition to presenting the design considerations, a demonstration of a complete digital design flow is given using the custom gates. An AES128 encryption/decryption engine is designed using the aforementioned digital flow in a commercial 180nm process. The resulting design has a ratio of maximum to minimum frequency variation over corners of only 50% with a 0.3V power supply where the same ratio with standard CMOS gates biased under the same supply voltage is 5600%. In addition, the custom gates are used to design a Wallace tree multiplier in an SOI 45nm process that is fully functional with an optimum energy power supply level of 0.34V with a typical operating frequency of 8 MHz having a variation over corners of 80%. For a proof of concept memory chip designed in this work, the architecture uses a logiccompatible CMOS process particularly suitable for embedded applications. The differential pair construct causes the read and refresh power to be independent of any process parameter including the within-die threshold voltage. The current stop feature keeps the read voltage transition low to further minimize read power. The bit cell operates in both single bit BASE2 and multi-bit BASE4 modes. An expression for the read signal was verified with bit cell simulations. These simulations also compare the performance impact of threshold voltage variance in the architecture with a standard gain cell. A DRAM bit cell array was fabricated in the XFab 180nm CMOS process. Measured waveforms closely match theoretical results obtained from a system simulation. The silicon retention time was measured at room temperature and is greater than 150 ms in BASE2 mode and greater than 75 ms in BASE4 mode. 180nm, 25C analysis predicts 0.8uW/Mbit refresh power at 630 MHz, the lowest in the literature. Further: the memory bit cell architecture presented here has a refresh power delay product several times lower than any other published architecture. The current controlled memory architecture in this work improves or overcomes the drawbacks of the 1T1C and gain cell memory architectures. A current controlled memory design was fabricated as a 131K bit array in an 180nm process to provide silicon proof. The bit cell configuration with shared read and write bit cells gives effectively two memory banks. The grouping of rows together into common source domains allows only two opamps to control the current in all the bit cells across the whole chip. The sense amplifiers have a globally controlled switching threshold point and keep their static power in the nano-amp range. The bit cells can operate either in BASE2 or BASE4 mode and the read bit line transitions are reduced with a current stop construct. Parts were received from the foundry in an 84-pin PLCC and were tested at a number of locations on the die. They proved to be fully functional in BASE4. The silicon retention time was measured at room temperature and was greater than four seconds

    Noninvasive Monitoring of Elevated Intramuscular Pressure in a Model Compartment Syndrome via Quantitative Fascial Motion

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    Compartment syndromes, conditions of elevated intramuscular pressure (IMP) resulting from trauma or chronic overuse, frequently require invasive IMP monitoring for accurate diagnosis. Our objective was to test a noninvasive ultrasound technique For estimating IMP based on fascial displacement waveforms from arterial blood pressure pulses. IMP was increased in the legs of 23 healthy adult subjects LIP to 80 mmHg Using two blood pressure cuffs covering the region from the knee to the ankle. Receiver operator characteristic curves and recursive partitioning were used to determine the sensitivity and specificity of diagnosing elevated IMP using fascial displacement, For one curve. in which several ultrasonic measurement parameters were used along with subject body mass index and blood pressure, the sensitivity and specificity for diagnosing normal IMP (below 30 mmHg) from elevated IMP (30 mm Hg and up) was 0.61 and 0.94, respectively. Recursive partitioning, in which IMP was divided into three ranges (normal \u3c30 \u3emmHg, midrange of 30-40 mmHg, and elevated \u3e= 50 mmHg), resulted in improved diagnostic sensitivity (0.77) with almost no change in specificity (0.93). (C) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:489-494 200

    Modeling inflammation and oxidative stress in gastrointestinal disease development using novel organotypic culture systems.

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    Gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), graft-versus-host disease (GVHD), and inflammatory bowel diseases such as ulcerative colitis and Crohn's disease are common human gastrointestinal diseases that share inflammation as a key driver for their development. A general outcome resulting from these chronic inflammatory conditions is increased oxidative stress. Oxidative stress is caused by the generation of reactive oxygen and nitrogen species that are part of the normal inflammatory response, but are also capable of damaging cellular DNA, protein, and organelles. Damage to DNA can include DNA strand breaks, point mutations due to DNA adducts, as well as alterations in methylation patterns leading to activation of oncogenes or inactivation of tumor suppressors. There are a number of significant long-term consequences associated with chronic oxidative stress, most notably cancer. Infiltrating immune cells and stromal components of tissue including fibroblasts contribute to dynamic changes occurring in tissue related to disease development. Immune cells can potentiate oxidative stress, and fibroblasts have the capacity to contribute to advanced growth and proliferation of the epithelium and any resultant cancers. Disease models for GERD, BE, GVHD, and ulcerative colitis based on three-dimensional human cell and tissue culture systems that recapitulate in vivo growth and differentiation in inflammatory-associated microphysiological environments would enhance our understanding of disease progression and improve our ability to test for disease-prevention strategies. The development of physiologically relevant, human cell-based culture systems is therefore a major focus of our research. These novel models will be of enormous value, allowing us to test hypotheses and advance our understanding of these disorders, and will have a translational impact allowing us to more rapidly develop therapeutic and chemopreventive agents. In summary, this work to develop advanced human cell-based models of inflammatory conditions will greatly improve our ability to study, prevent, and treat GERD, BE, GVHD, and inflammatory bowel disease. The work will also foster the development of novel therapeutic and preventive strategies that will improve patient care for these important clinical conditions

    Understanding the role of infant and toddler nutrition on population health : epidemiological resources in Australasia

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    The importance of understanding the relationship between weaning and toddler nutrition, which in turn impacts on health in later life, is highlighted. Emphasis is placed on the need for epidemiological research in Australasia for population-specific information on early life diet and health.Rebecca K Golley, Lisa G Smithers, Karen Campbell, and John Lync

    Dispersion monitoring for high-speed WDM networks via two-photon absorption in a semiconductor microcavity

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    Due to the continued demand for bandwidth, network operators have to increase the data rates at which individual wavelengths operate at. As these data rates will exceed 100 Gbit/s in the next 5-10 years, it will be crucial to be able to monitor and compensate for the amount of chromatic dispersion encountered by individual wavelength channels. This paper will focus on the use of the novel nonlinear optical-to-electrical conversion process of two-photon absorption (TPA) for dispersion monitoring. By incorporating a specially designed semiconductor microcavity, the TPA response becomes wavelength dependent, thus allowing simultaneous channel selection and monitoring without the need for external wavelength filterin

    The role of the automation development group in analytical research and development at Dupont Merck

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    Laboratory robotics has been firmly established in many non-QC laboratories as a valuable tool for automating pharmaceutical dosage form analysis. Often a single project or product line is used to justify an initial robot purchase thus introducing robotics to the laboratory for the first time. However, to gain widespread acceptance within the laboratory and to justify further investment in robotics, existing robots must be used to develop analyses for existing manual methods as well as new projects beyond the scope off the original purchase justification. The Automation Development Group in Analytical Research and Development is a team of analysts primarily devoted to developing new methods and adapting existing methods for the robot. This team approach developed the expertise and synergy necessary to significantly expand the contribution of robotics to automation in the authors' laboratory

    Epidemiology, genetics, and subtyping of preserved ratio impaired spirometry (PRISm) in COPDGene.

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    BackgroundPreserved Ratio Impaired Spirometry (PRISm), defined as a reduced FEV1 in the setting of a preserved FEV1/FVC ratio, is highly prevalent and is associated with increased respiratory symptoms, systemic inflammation, and mortality. Studies investigating quantitative chest tomographic features, genetic associations, and subtypes in PRISm subjects have not been reported.MethodsData from current and former smokers enrolled in COPDGene (n = 10,192), an observational, cross-sectional study which recruited subjects aged 45-80 with ≥10 pack years of smoking, were analyzed. To identify epidemiological and radiographic predictors of PRISm, we performed univariate and multivariate analyses comparing PRISm subjects both to control subjects with normal spirometry and to subjects with COPD. To investigate common genetic predictors of PRISm, we performed a genome-wide association study (GWAS). To explore potential subgroups within PRISm, we performed unsupervised k-means clustering.ResultsThe prevalence of PRISm in COPDGene is 12.3%. Increased dyspnea, reduced 6-minute walk distance, increased percent emphysema and decreased total lung capacity, as well as increased segmental bronchial wall area percentage were significant predictors (p-value <0.05) of PRISm status when compared to control subjects in multivariate models. Although no common genetic variants were identified on GWAS testing, a significant association with Klinefelter's syndrome (47XXY) was observed (p-value < 0.001). Subgroups identified through k-means clustering include a putative "COPD-subtype", "Restrictive-subtype", and a highly symptomatic "Metabolic-subtype".ConclusionsPRISm subjects are clinically and genetically heterogeneous. Future investigations into the pathophysiological mechanisms behind and potential treatment options for subgroups within PRISm are warranted.Trial registrationClinicaltrials.gov Identifier: NCT000608764

    Cdx1 and c-Myc Foster the Initiation of Transdifferentiation of the Normal Esophageal Squamous Epithelium toward Barrett's Esophagus

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    Barrett's esophagus is a premalignant condition whereby the normal stratified squamous esophageal epithelium undergoes a transdifferentiation program resulting in a simple columnar epithelium reminiscent of the small intestine. These changes are typically associated with the stratified squamous epithelium chronically exposed to acid and bile salts as a result of gastroesophageal reflux disease (GERD). Despite this well-defined epidemiologic association between acid reflux and Barrett's esophagus, the genetic changes that induce this transdifferentiation process in esophageal keratinocytes have remained undefined.To begin to identify the genetic changes responsible for transdifferentiaiton in Barrett's esophagus, we performed a microarray analysis of normal esophageal, Barrett's esophagus and small intestinal biopsy specimens to identify candidate signaling pathways and transcription factors that may be involved. Through this screen we identified the Cdx1 homeodomain transcription factor and the c-myc pathway as possible candidates. Cdx1 and c-myc were then tested for their ability to induce transdifferentiation in immortalized human esophageal keratinocytes using organotypic culturing methods. Analyses of these cultures reveal that c-myc and cdx1 cooperate to induce mucin production and changes in keratin expression that are observed in the epithelium of Barrett's esophagus.These data demonstrate the ability of Cdx1 and c-myc to initiate the earliest stages of transdifferentiation of esophageal keratinocytes toward a cell fate characteristic of Barrett's esophagus

    Pre-pregnancy predictors of hypertension in pregnancy among Aboriginal and Torres Strait Islander women in north Queensland, Australia; a prospective cohort study

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    BACKGROUND Compared to other Australian women, Indigenous women are frequently at greater risk for hypertensive disorders of pregnancy. We examined pre-pregnancy factors that may predict hypertension in pregnancy in a cohort of Aboriginal and Torres Strait Islander women in north Queensland. METHODS Data on a cohort of 1009 Indigenous women of childbearing age (15–44 years) who participated in a 1998–2000 health screening program in north Queensland were combined with 1998–2008 Queensland hospitalisations data using probabilistic data linkage. Data on the women in the cohort who were hospitalised for birth (n = 220) were further combined with Queensland perinatal data which identified those diagnosed with hypertension in pregnancy. RESULTS Of 220 women who gave birth, 22 had hypertension in the pregnancy after their health check. The mean age of women with and without hypertension was similar (23.7 years and 23.9 years respectively) however Aboriginal women were more affected compared to Torres Strait Islanders. Pre-pregnancy adiposity and elevated blood pressure at the health screening program were predictors of a pregnancy affected by hypertension. After adjusting for age and ethnicity, each 1 cm increase in waist circumference showed a 4% increased risk for hypertension in pregnancy (PR 1.04; 95% CI; 1.02-1.06); each 1 point increase in BMI showed a 9% adjusted increase in risk (1.09; 1.04-1.14). For each 1 mmHg increase in baseline systolic blood pressure there was an age and ethnicity adjusted 6% increase in risk and each 1 mmHg increase in diastolic blood pressure showed a 7% increase in risk (1.06; 1.03-1.09 and 1.07; 1.03-1.11 respectively). Among those free of diabetes at baseline, the presence of the metabolic syndrome (International Diabetes Federation criteria) predicted over a three-fold increase in age-ethnicity-adjusted risk (3.5; 1.50-8.17). CONCLUSIONS Pre-pregnancy adiposity and features of the metabolic syndrome among these young Aboriginal and Torres Strait Islander women track strongly to increased risk of hypertension in pregnancy with associated risks to the health of babies.Sandra K Campbell, John Lynch, Adrian Esterman and Robyn McDermot
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