10 results on '"Leduc, R."'
Search Results
2. Open Science Cyber Risk Profile
- Author
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Peisert, S, Peisert, S, Welch, V, Adams, A, Bevier, R, Dopheide, M, LeDuc, R, Meunier, P, Schwab, S, Stocks, K, Peisert, S, Peisert, S, Welch, V, Adams, A, Bevier, R, Dopheide, M, LeDuc, R, Meunier, P, Schwab, S, and Stocks, K
- Abstract
The Open Science Cyber Risk Profile (OSCRP) is a joint project of the Center for Trustworthy Scientific Cyberinfrastructure and the Department of Energy's Energy Sciences Network (ESnet). More information can be found at: http://trustedci.org/oscrp
- Published
- 2017
3. Performance of the Caltech Submillimeter Observatory Dual-Color 180-720 GHz Balanced SIS Receivers
- Author
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Kooi, J. W., Chamberlin, R. A., Monje, R., Kovacs, A., Rice, F., Yoshida, H., Force, B., Cooper, K., Miller, D., Gould, M., Lis, D., Bumble, B., LeDuc, R., Stern, J. A., Phillips, T. G., Kooi, J. W., Chamberlin, R. A., Monje, R., Kovacs, A., Rice, F., Yoshida, H., Force, B., Cooper, K., Miller, D., Gould, M., Lis, D., Bumble, B., LeDuc, R., Stern, J. A., and Phillips, T. G.
- Abstract
We report on balanced SIS receivers covering the astronomical important 180-720 GHz submillimeter atmospheric window. To facilitate remote observations and automated spectral line surveys, fully synthesized local oscillators are employed. High-current-density Nb-AlN-Nb superconducting-insulating-superconducting (SIS) tunnel junctions are used as the mixing element. The measured double-sideband (DSB) 230 GHz receiver noise temperature, uncorrected for optics loss, ranges from 50K at 185 GHz, 33K at 246 GHz, to 51K at 280 GHz. In this frequency range the mixer has a DSB conversion gain of 0 +- 1.5 dB. The measured 460 GHz double-sideband receiver noise temperature, uncorrected for optics loss, is 32K at 400 GHz, 34K at 460 GHz, and 61K at 520 GHz. Similar to the 230 GHz balanced mixer, the DSB mixer conversion gain is 1 +- 1 dB. To help optimize performance, the mixer IF circuits and bias injection are entirely planar by design. Dual-frequency observation, by means of separating the incoming circular polarized electric field into two orthogonal components, is another important mode of operation offered by the new facility instrumentation. Instrumental stability is excellent supporting the LO noise cancellation properties of the balanced mixer configuration. In the spring of 2012 the dual-frequency 230/460 SIS receiver was successfully installed at Caltech Submillimeter Observatory (CSO), Mauna Kea, HI., Comment: Accepted for publication in IEEE/TST
- Published
- 2014
- Full Text
- View/download PDF
4. Lithographed spectrometers for tomographic line mapping of the Epoch of Reionization
- Author
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Holland, Wayne S., Zmuidzinas, Jonas, O'Brient, R., Bock, J. J., Bradford, C. M., Crites, A., Duan, R., Hailey-Dunsheath, S., Hunasek, J., LeDuc, R., Shirokoff, E., Staniszewski, Z., Turner, A., Zemcov, M., Holland, Wayne S., Zmuidzinas, Jonas, O'Brient, R., Bock, J. J., Bradford, C. M., Crites, A., Duan, R., Hailey-Dunsheath, S., Hunasek, J., LeDuc, R., Shirokoff, E., Staniszewski, Z., Turner, A., and Zemcov, M.
- Abstract
The Tomographic Ionized carbon Mapping Experiment (TIME) is a multi-phased experiment that will topographically map [CII] emission from the Epoch of Reionization. We are developing lithographed spectrometers that couple to TES bolometers in anticipation of the second generation instrument. Our design intentionally mirrors many features of the parallel SuperSpec project, inductively coupling power from a trunk-line microstrip onto half-wave resonators. The resonators couple to a rat-race hybrids that feeds TES bolometers. Our 25 channel prototype shows spectrally positioned lines roughly matching design with a receiver optical efficiency of 15-20%, a level that is dominated by loss in components outside the spectrometer.
- Published
- 2014
5. Performance of the Caltech Submillimeter Observatory Dual-Color 180-720 GHz Balanced SIS Receivers
- Author
-
Kooi, J. W., Chamberlin, R. A., Monje, R., Kovacs, A., Rice, F., Yoshida, H., Force, B., Cooper, K., Miller, D., Gould, M., Lis, D., Bumble, B., LeDuc, R., Stern, J. A., Phillips, T. G., Kooi, J. W., Chamberlin, R. A., Monje, R., Kovacs, A., Rice, F., Yoshida, H., Force, B., Cooper, K., Miller, D., Gould, M., Lis, D., Bumble, B., LeDuc, R., Stern, J. A., and Phillips, T. G.
- Abstract
We report on balanced SIS receivers covering the astronomical important 180-720 GHz submillimeter atmospheric window. To facilitate remote observations and automated spectral line surveys, fully synthesized local oscillators are employed. High-current-density Nb-AlN-Nb superconducting-insulating-superconducting (SIS) tunnel junctions are used as the mixing element. The measured double-sideband (DSB) 230 GHz receiver noise temperature, uncorrected for optics loss, ranges from 50K at 185 GHz, 33K at 246 GHz, to 51K at 280 GHz. In this frequency range the mixer has a DSB conversion gain of 0 +- 1.5 dB. The measured 460 GHz double-sideband receiver noise temperature, uncorrected for optics loss, is 32K at 400 GHz, 34K at 460 GHz, and 61K at 520 GHz. Similar to the 230 GHz balanced mixer, the DSB mixer conversion gain is 1 +- 1 dB. To help optimize performance, the mixer IF circuits and bias injection are entirely planar by design. Dual-frequency observation, by means of separating the incoming circular polarized electric field into two orthogonal components, is another important mode of operation offered by the new facility instrumentation. Instrumental stability is excellent supporting the LO noise cancellation properties of the balanced mixer configuration. In the spring of 2012 the dual-frequency 230/460 SIS receiver was successfully installed at Caltech Submillimeter Observatory (CSO), Mauna Kea, HI., Comment: Accepted for publication in IEEE/TST
- Published
- 2014
- Full Text
- View/download PDF
6. Condition Monitoring for Rotational Machinery
- Author
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Volante, Daniel C., Mohrenschildt, Martin v., Khedri, R., Leduc, R., Computing and Software, Volante, Daniel C., Mohrenschildt, Martin v., Khedri, R., Leduc, R., and Computing and Software
- Abstract
Vibrating screens are industrial machines used to sort aggregates through their high rotational accelerations. Utilized in mining operations, they are able to screen dozens of tonnes of material per hour. To enhance maintenance and troubleshooting, this thesis introduces a vibration based condition monitoring system capable of observing machine operation. Using acceleration data collected from remote parts of the machine, software continuously detects for abnormal operation triggered by fault conditions. Users are to be notified in the event of a fault and be provided with relevant information. Acceleration data is acquired from a set of sensor devices that are mounted to specified points on the vibrating screen. Data is then wirelessly transmitted to a centralized unit for digital signal processing. Existing sensor devices developed for a previous project have been upgraded and integrated into the monitoring system. Alternative communication technologies and the utilized Wi-Fi network are examined and discussed. The condition monitoring system's hardware and software was designed following engineering principles. Development produced a functional prototype system, implementing the monitoring process. The monitoring technique utilizes signal filtering and processing to compute a set of variables that reveal the status of the machine. Decision making strategies are then employed as to determine when a fault has occurred. Testing performed on the developed monitoring system has also been documented. The performance of the prototype system is examined as different fault scenarios are induced and monitored. Results and descriptions of virtual simulations and live industrial experiments are presented. The relationships between machine faults and detected fault signatures are also discussed., Master of Applied Science (MASc)
- Published
- 2011
7. 10 mM glucosamine prevents activation of proADAMTS5 (aggrecanase-2) in transfected cells by interference with post-translational modification of furin
- Author
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McCulloch, D. R., Wiley, J. D., Longpre, J.-M., Leduc, R., Apte, S. S., McCulloch, D. R., Wiley, J. D., Longpre, J.-M., Leduc, R., and Apte, S. S.
- Abstract
Objective Glucosamine has been previously shown to suppress cartilage aggrecan catabolism in explant cultures. We determined the effect of glucosamine on ADAMTS5 (a disintegrin-like and metalloprotease domain (reprolysin type) with thrombospondin type-1 motifs 5), a major aggrecanase in osteoarthritis, and investigated a potential mechanism underlying the observed effects. Design HEK293F and CHO-K1 cells transiently transfected with ADAMTS5 cDNA were treated with glucosamine or the related hexosamine mannosamine. Glucosamine effects on FURIN transcription were determined by quantitative RT-PCR. Effects on furin-mediated processing of ADAMTS5 zymogen, and aggrecan processing by glucosamine-treated cells, were determined by western blotting. Post-translational modification of furin and N-glycan deficient furin mutants generated by site-directed mutagenesis was analyzed by western blotting, and the mutants were evaluated for their ADAMTS5 processing ability in furin-deficient CHO-RPE.40 cells. Results Ten mM glucosamine and 5–10 mM mannosamine reduced excision of the ADAMTS5 propeptide, indicating interference with the propeptide excision mechanism, although mannosamine compromised cell viability at these doses. Although glucosamine had no effect on furin mRNA levels, western blot of furin from glucosamine-treated cells suggested altered post-translational modification. Glucosamine treatment led to decreased glycosylation of cellular furin, with reduced furin autoactivation as the consequence. Recombinant furin treated with peptide N-glycanase F had reduced activity against a synthetic peptide substrate. Indeed, site-directed mutagenesis of two furin N-glycosylation sites, Asn387 and Asn440, abrogated furin activation and this mutant was unable to rescue ADAMTS5 processing in furin-deficient cells. Conclusions Ten mM glucosamine reduces excision of the ADAMTS5 propeptide via interfer
- Published
- 2010
8. Human fur gene encodes a yeast KEX2-like endoprotease that cleaves pro-beta-NGF in vivo.
- Author
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Bresnahan, P, Bresnahan, P, Leduc, R, Thomas, L, THORNER, Jeremy W., Gibson, H, Brake, A, Barr, P, Thomas, G, Bresnahan, P, Bresnahan, P, Leduc, R, Thomas, L, THORNER, Jeremy W., Gibson, H, Brake, A, Barr, P, and Thomas, G
- Abstract
Extracts from BSC-40 cells infected with vaccinia recombinants expressing either the yeast KEX2 prohormone endoprotease or a human structural homologue (fur gene product) contained an elevated level of a membrane-associated endoproteolytic activity that could cleave at pairs of basic amino acids (-LysArg- and -ArgArg-). The fur-directed activity (furin) shared many properties with Kex2p including activity at pH 7.3 and a requirement for calcium. By using antifurin antibodies, immunoblot analysis detected two furin translation products (90 and 96 kD), while immunofluorescence indicated localization to the Golgi apparatus. Coexpression of either Kex2p or furin with the mouse beta-nerve growth factor precursor (pro-beta-NGF) resulted in greatly enhanced conversion of the precursor to mature nerve growth factor. Thus, the sequence homology shared by furin and the yeast KEX2 prohormone processing enzyme is reflected by significant functional homology both in vitro and in vivo.
- Published
- 1990
9. Human fur gene encodes a yeast KEX2-like endoprotease that cleaves pro-beta-NGF in vivo.
- Author
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Bresnahan, PA, Bresnahan, PA, Leduc, R, Thomas, L, Thorner, J, Gibson, HL, Brake, AJ, Barr, PJ, Thomas, G, Bresnahan, PA, Bresnahan, PA, Leduc, R, Thomas, L, Thorner, J, Gibson, HL, Brake, AJ, Barr, PJ, and Thomas, G
- Abstract
Extracts from BSC-40 cells infected with vaccinia recombinants expressing either the yeast KEX2 prohormone endoprotease or a human structural homologue (fur gene product) contained an elevated level of a membrane-associated endoproteolytic activity that could cleave at pairs of basic amino acids (-LysArg- and -ArgArg-). The fur-directed activity (furin) shared many properties with Kex2p including activity at pH 7.3 and a requirement for calcium. By using antifurin antibodies, immunoblot analysis detected two furin translation products (90 and 96 kD), while immunofluorescence indicated localization to the Golgi apparatus. Coexpression of either Kex2p or furin with the mouse beta-nerve growth factor precursor (pro-beta-NGF) resulted in greatly enhanced conversion of the precursor to mature nerve growth factor. Thus, the sequence homology shared by furin and the yeast KEX2 prohormone processing enzyme is reflected by significant functional homology both in vitro and in vivo.
- Published
- 1990
10. Water treatment and flotation studies on recycle water from pyrochlore processing plant.
- Author
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Gehr R., Processing of complex ores Halifax, Nova Scotia 20-Aug-8924-Aug-89, Bayat-Mokhtari F., Finch J.A., Leduc R., Rao S.R., Gehr R., Processing of complex ores Halifax, Nova Scotia 20-Aug-8924-Aug-89, Bayat-Mokhtari F., Finch J.A., Leduc R., and Rao S.R.
- Abstract
Microflotation studies on the recycle water showed that a lowering of the organics concentration reduces the flotation recovery of some of the undesired silicate minerals, albite and chlorite. Treatment with activated carbon, led to a lower recovery of microcline. Treatment of water by ion exchange processes improved pyrochlore recovery by as much as 40% at higher pH., Microflotation studies on the recycle water showed that a lowering of the organics concentration reduces the flotation recovery of some of the undesired silicate minerals, albite and chlorite. Treatment with activated carbon, led to a lower recovery of microcline. Treatment of water by ion exchange processes improved pyrochlore recovery by as much as 40% at higher pH.
- Published
- 1989
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