14 research outputs found

    Spaceborne synthetic-aperture imaging radars: Applications, techniques, and technology

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    In the last four years, the first two Earth-orbiting, space-borne, synthetic-aperture imaging radars (SAR) were successfully developed and operated. This was a major achievement in the development of spaceborne radar sensors and ground processors. The data acquired with these sensors extended the capability of Earth resources and ocean-surface observation into a new region of the electromagnetic spectrum. This paper is a review of the different aspects of spaceborne imaging radars. It includes a review of: 1) the unique characteristics of space-borne SAR systems; 2) the state of the art in spaceborne SAR hardware and SAR optical and digital processors; 3) the different data-handling techniques; and 4) the different applications of spaceborne SAR data

    Spaceborne synthetic-aperture imaging radars: Applications, techniques, and technology

    Get PDF
    In the last four years, the first two Earth-orbiting, space-borne, synthetic-aperture imaging radars (SAR) were successfully developed and operated. This was a major achievement in the development of spaceborne radar sensors and ground processors. The data acquired with these sensors extended the capability of Earth resources and ocean-surface observation into a new region of the electromagnetic spectrum. This paper is a review of the different aspects of spaceborne imaging radars. It includes a review of: 1) the unique characteristics of space-borne SAR systems; 2) the state of the art in spaceborne SAR hardware and SAR optical and digital processors; 3) the different data-handling techniques; and 4) the different applications of spaceborne SAR data

    Glucocorticoid signaling enhances expression of glucose-sensing molecules in immature pancreatic beta-like cells derived from murine embryonic stem cells in vitro

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    Pluripotent stem cells may serve as an alternative source of beta-like cells for replacement therapy of type 1 diabetes; however, the beta-like cells generated in many differentiation protocols are immature. The maturation of endogenous beta cells involves an increase in insulin expression starting in late gestation and a gradual acquisition of the abilities to sense glucose and secrete insulin by week 2 after birth in mice; however, what molecules regulate these maturation processes are incompletely known. Here, we aim to identify small molecules that affect immature beta cells. A cell-based assay, employing pancreatic beta-like cells derived from murine embryonic stem (ES) cells harboring a transgene containing an Insulin 1-promoter driven enhanced green fluorescent protein reporter, was used to screen a compound library (NIH Clinical Collection-003). Cortisone, a glucocorticoid, was among five positive hit compounds. Quantitative RT-PCR analysis revealed that glucocorticoids enhance the gene expression of not only insulin 1 but also glucose transporter-2 (Glut2; Slc2a2) and glucokinase (Gck), two molecules important for glucose sensing. Mifepristone, a pharmacological inhibitor of glucocorticoid receptor (GR) signaling, reduced the effects of glucocorticoids on Glut2 and Gck expression. The effects of glucocorticoids on ES-derived cells were further validated in immature primary islets. Isolated islets from 1-week-old mice had an increased Glut2 and Gck expression in response to a 4-day treatment of exogenous hydrocortisone in vitro. Gene deletion of GR in beta cells using rat insulin 2 promoter-driven Cre crossed with GRflox/flox mice resulted in a reduced gene expression of Glut2, but not Gck, and an abrogation of insulin secretion when islets were incubated in 0.5 mM D-glucose and stimulated by 17 mM D-glucose in vitro. These results demonstrate that glucocorticoids positively regulate glucose sensors in immature murine beta-like cells

    An Institutional Theory perspective on sustainable practices across the dairy supply chain

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    AbstractThe need for sustainable practices in the food supply chain, particularly in the area of energy reduction, is becoming acute. The food industry currently has to contend with multiple competing pressures alongside the new challenges of sustainable production. We applied Institutional Theory to explore the role of supermarkets in the development of legitimate sustainable practices across the dairy supply chains. The paper focuses on dairy supply chain organizations and their consumption of energy. We conducted 70 semi-structured telephone interviews with various stakeholders across the supply chain. Findings revealed that the majority of actors in the supply chain identified supermarkets as the dominant player, and that the supermarkets exert pressure on other smaller organizations across the supply chain. Although some organizations wished to pursue a sustainable agenda through integrating new rules and legitimate practices within their own organization, the dominant logic appeared to be one of cost reduction and profit maximization. There was also evidence that supermarkets and other large organizations attempt to replicate publicly available information on green successes for image purposes. We conclude that the dominant logic of cost reduction is so well established that challenging the dominant logic may prove difficult. The challenge is therefore to complement the dominant logic with sustainable practices across the whole supply chain, a role Government needs to play. This will require a broader more systemic approach to encouraging sustainable practices including investment and financing practices, so that all members of the dairy supply chain can co-operate and contribute to energy reduction

    Glucocorticoid signaling enhances expression of glucose-sensing molecules in immature pancreatic beta-like cells derived from murine embryonic stem cells in vitro

    Get PDF
    Pluripotent stem cells may serve as an alternative source of beta-like cells for replacement therapy of type 1 diabetes; however, the beta-like cells generated in many differentiation protocols are immature. The maturation of endogenous beta cells involves an increase in insulin expression starting in late gestation and a gradual acquisition of the abilities to sense glucose and secrete insulin by week 2 after birth in mice; however, what molecules regulate these maturation processes are incompletely known. Here, we aim to identify small molecules that affect immature beta cells. A cell-based assay, employing pancreatic beta-like cells derived from murine embryonic stem (ES) cells harboring a transgene containing an Insulin 1-promoter driven enhanced green fluorescent protein reporter, was used to screen a compound library (NIH Clinical Collection-003). Cortisone, a glucocorticoid, was among five positive hit compounds. Quantitative RT-PCR analysis revealed that glucocorticoids enhance the gene expression of not only insulin 1 but also glucose transporter-2 (Glut2; Slc2a2) and glucokinase (Gck), two molecules important for glucose sensing. Mifepristone, a pharmacological inhibitor of glucocorticoid receptor (GR) signaling, reduced the effects of glucocorticoids on Glut2 and Gck expression. The effects of glucocorticoids on ES-derived cells were further validated in immature primary islets. Isolated islets from 1-week-old mice had an increased Glut2 and Gck expression in response to a 4-day treatment of exogenous hydrocortisone in vitro. Gene deletion of GR in beta cells using rat insulin 2 promoter-driven Cre crossed with GRflox/flox mice resulted in a reduced gene expression of Glut2, but not Gck, and an abrogation of insulin secretion when islets were incubated in 0.5 mM D-glucose and stimulated by 17 mM D-glucose in vitro. These results demonstrate that glucocorticoids positively regulate glucose sensors in immature murine beta-like cells

    NASA Spaceborne Radar Missions: CloudSat and QuickScat: To Observe Clouds and Sea Surface Winds

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    CloudSat is a joint US/Canadian spaceborne science mission for global measurements of atmospheric cloud structures. Cloud Profiling Radar (CPR) has already captured many stunning profiles of cloud/precipitation structures, some have not been seen before. Observation of storms' cloud formation, in conjunction with data from other remote sensors, will hopefully improve quality of natural hazards' forecasts

    THE DECISION TREE APPROACH TO CLASSIFICATION.

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    Cloudsat Radar Instrument Design and Development Status

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    The Cloud Profiling Radar is the key science instrument for the CloudSat Mission to acquire a global data set of vertical atmospheric cloud structure and its variability. CPR is a 94 GHz nadir-looking radar that measures the power backscattered by clouds as a function of distance from the radar. This sensor is expected to provide cloud measurements at a 500-m vertical resolution and a 1.5-km horizontal resolution. CPR will operate in a short pulse mode and will yield measurements at a minimum detectable sensitivity of -28 dBZ
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