Science.gov

Sample records for vims wavelength scale

  1. Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

    USGS Publications Warehouse

    Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

    2010-01-01

    Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector

  2. Global-scale surface spectral variations on Titan seen from Cassini/VIMS

    USGS Publications Warehouse

    Barnes, J.W.; Brown, R.H.; Soderblom, L.; Buratti, B.J.; Sotin, C.; Rodriguez, S.; Le, Mouelic S.; Baines, K.H.; Clark, R.; Nicholson, P.

    2007-01-01

    We present global-scale maps of Titan from the Visual and Infrared Mapping Spectrometer (VIMS) instrument on Cassini. We map at 64 near-infrared wavelengths simultaneously, covering the atmospheric windows at 0.94, 1.08, 1.28, 1.6, 2.0, 2.8, and 5 ??m with a typical resolution of 50 km/pixel or a typical total integration time of 1 s. Our maps have five to ten times the resolution of ground-based maps, better spectral resolution across most windows, coverage in multiple atmospheric windows, and represent the first spatially resolved maps of Titan at 5 ??m. The VIMS maps provide context and surface spectral information in support of other Cassini instruments. We note a strong latitudinal dependence in the spectral character of Titan's surface, and partition the surface into 9 spectral units that we describe in terms of spectral and spatial characteristics. ?? 2006 Elsevier Inc. All rights reserved.

  3. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure: the VIMS perspective

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Nicholson, P. D.; Hedmann, M. M.; Clark, R. N.; Cerroni, P.; Spilker, L. J.; Colwell, J.; Bradley, T.

    2012-04-01

    Saturn has the most prominent and complex ring system in our solar system, extending along radial axis from 74658 km (inner C ring edge) to 136780 km (outer A). The physical and dynamical properties of ring particles can be fully understood only using a broad spectral range, which allow us to recognize very different processes. In this context, the scientific goal of our investigation is the study of Saturn's rings particle properties using combined datasets returned from different instruments aboard the Cassini mission. We are merging rings observations and compare results collected by Cassini's UV Imaging Spectrometer (UVIS), Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS) and Composite Infrared Spectrometer (CIRS). Merging multi-wavelength data sets allow us to test different thermal models, combining the effects of particle albedo, regolith composition, grain size and thermal properties with the ring structure. In this work we report about the VIMS contributions to this investigation, coming from the analysis of 0.35-5.1 µm spectra of A, B, C rings and Cassini Division. VIMS, in fact, has the capabilities to determine ring particles composition (water ice vs. chromophores mixed within ice), surface regolith grain size and particle albedo. After having described the dataset considered in this work (several rings radial mosaics taken at 12° ≤ phase ≤ 136° and -21° ≤ opening angle ≤ +5°) and the method to reduce data to spectrograms, we explain how the spectral indicators we have selected (slopes and band parameters) allow us to infer ring particle properties across different regions. Specifically, we report about: 1) the variations induced by illumination phase on visible reddening and water ice bands depth; 2) the average composition and regolith grain size of ring particles in A, B, C rings and CD; 3) an application of Hapke's model to compare VIMS data with synthetic spectra.

  4. Effective wavelength scaling of rectangular aperture antennas.

    PubMed

    Chen, Yuanyuan; Yu, Li; Zhang, Jiasen; Gordon, Reuven

    2015-04-20

    We investigate the resonances of aperture antennas from the visible to the terahertz regime, with comparison to comprehensive simulations. Simple piecewise analytic behavior is found for the wavelength scaling over the entire spectrum, with a linear regime through the visible and near-IR. This theory will serve as a useful and simple design tool for applications including biosensors, nonlinear plasmonics and surface enhanced spectroscopies. PMID:25969079

  5. Poster 13: Large-scale simultaneous mapping of Titan's aerosol opacity and surface albedo by a new massive inversion method of Cassini/VIMS data

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Rodriguez, Sebastien; Sotin, Christophe; Rannou, Pascal; Bezard, Bruno; Solomonidou, Anezina; Coustenis, Athena; Appere, Thomas; Cornet, Thomas; Le Mouelic, Stephane%F. Aa(Aim Cea Saclay; Lesia Observatoire de Paris), Ab(Aim Cea Saclay; Universite Paris 7), Ac(Jpl; Lpg Nantes), Ad(Gsma Reims), Ae(Lesia Observatoire De Paris), Af(Jpl), Ag(Lesia Observatoire De Paris), Ah(Aim Cea Saclay), Ai(Esac/Esa), Aj(Lpg Nantes)

    2016-06-01

    We have still limited information on Titan's surface albedo in the near-infrared. Only few spectral windows exist in between the intense methane bands, and even those windows are strongly affected by atmospheric contributions (absorption, scattering). Yet, this part of the spectrum is important to determine the surface composition thanks to the wealth of absorption bands by minerals and ices present there. A radiative transfer model is an effective tool to take the atmospheric effects into consideration in the analysis (e.g. Rannou et al. 2010, Griffith et al 2012, Solomonidou et al. 2016,...), but it is too time-consuming to process the whole VIMS hyperspectral dataset (millions of spectra) and create large-scale maps of the surface albedo. To overcome this problem, we developed an inversion method of VIMS data that employs lookup tables of synthetic spectra produced by a state-of-the-art radiative transfer model (described in its original form in Hirtzig et al. 2013). The heavy computational part (calling the radiative transfer model) is thus done only once for all during the creation of the modeled spectra. We updated the model with new methane spectroscopy and the new aerosol parameters we found in our analysis of the VIMS Emission Phase Function (see the other Maltagliati et al. abstract in this workshop). We analyzed in detail the behavior of the spectra as a function of the free parameters of the model (three inputs, the incidence, emergence and azimuth angles; and two products: the aerosol opacity and the surface albedo) in order to create an optimized grid for the lookup table. The lookup tables were then grafted onto an ad-hoc inversion model. Our method can process a whole 64x64 VIMS datacube in few minutes, with a gain in computational time of a factor of more than one thousand with respect to the standard method. This will consent for the first time a truly massive inversion of VIMS data and large-scale acquisition of Titan's surface albedo, paving the

  6. Voyager Interstellar Mission (VIM)

    NASA Technical Reports Server (NTRS)

    Rudd, R.; Textor, G.

    1991-01-01

    The DSN (Deep Space Network) mission support requirements for the Voyager Interstellar Mission (VIM) are summarized. The general objectives of the VIM are to investigate the interplanetary and interstellar media and to continue the Voyager program of ultraviolet astronomy. The VIM will utilize both Voyager spacecraft for the period from January 1990 through December 2019. The mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, control and support systems; and tracking support responsibility.

  7. Principal components analysis of Jupiter VIMS spectra

    USGS Publications Warehouse

    Bellucci, G.; Formisano, V.; D'Aversa, E.; Brown, R.H.; Baines, K.H.; Bibring, J.-P.; Buratti, B.J.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.; Chamberlain, M.C.; Hansen, G.; Hibbits, K.; Showalter, M.; Filacchione, G.

    2004-01-01

    During Cassini - Jupiter flyby occurred in December 2000, Visual-Infrared mapping spectrometer (VIMS) instrument took several image cubes of Jupiter at different phase angles and distances. We have analysed the spectral images acquired by the VIMS visual channel by means of a principal component analysis technique (PCA). The original data set consists of 96 spectral images in the 0.35-1.05 ??m wavelength range. The product of the analysis are new PC bands, which contain all the spectral variance of the original data. These new components have been used to produce a map of Jupiter made of seven coherent spectral classes. The map confirms previously published work done on the Great Red Spot by using NIMS data. Some other new findings, presently under investigation, are presented. ?? 2004 Published by Elsevier Ltd on behalf of COSPAR.

  8. Seasonal temperature variations observed by Cassini-VIMS on Saturn's satellites

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, Fabrizio; D'Aversa, Emiliano; Tosi, Federico; Ciarniello, Mauro; Clark, Roger N.; Brown, Robert H.; Buratti, Bonnie J.; Cruikshank, Dale P.; Dalle Ore, Cristina M.; Scipioni, Francesca; Cerroni, Priscilla

    2015-04-01

    We report about temperature maps of Mimas, Enceladus, Tethys, Dione and Rhea derived from Cassini/VIMS data. Observations taken during the entire duration of the Cassini mission (2004-2014) were processed. Since equinox occurred in 2009, this dataset includes both pre and post equinox viewing geometries. VIMS data taken at spatial resolution of 20-40 km/pixel allow us to study the correlation of the temperature at regional scale resolution with solar illumination conditions, geological features and seasons. The retrieval of the temperature from IR reflectance data is based on the comparison with laboratory measurements (Clark et al., Icarus 218, 831, 2012): when a sample of pure crystalline water ice particles is cooled, the 3.6 µm peak moves towards shorter wavelengths, from about 3.65 µm at T=123 K to about 3.55 µm at T=88 K. Mastrapa et al. (ApJ 701, 104, 2009) have measured a similar trend also in the imaginary part (k) of the refractive index of water ice when a sample is cooled from T=140 K to 20 K. Being Saturn's satellites surfaces dominated by water ice (Filacchione et al., Icarus 220, 1064, 2012), the measurement of the wavelength at which the 3.6 µm reflectance peak occurs can be considered as a good temperature marker. This method was already applied to Saturn rings VIMS mosaics to retrieve ring particles temperature (Filacchione et al., Icarus 241, 45, 2014). By using geometry projection techniques applied to VIMS data, we have mapped temperature variations as a function of LST and season on the regular satellites surfaces. Pre and post-equinox temperature maps built at the same LST allow us to follow seasonal variations across summer and winter hemispheres. Moreover, temperature variations seen across satellites surfaces appear correlated with geological features, leading-trailing asymmetries, local color patterns and equatorial radiation lenses.

  9. Spectral properties and temperature radial profiles of Saturn's main rings by Cassini-VIMS: variability with solar phase and elevation

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, F.; Ciarniello, M.; Clark, R. N.; Nicholson, P. D.; Cruikshank, D. P.; Brown, R. H.; Cuzzi, J. N.; Altobelli, N.; Spilker, L. J.; Hedman, M. M.; Dalle Ore, C. M.; Cerroni, P.

    2013-10-01

    We report about Saturn's rings average spectral properties and temperature as retrieved from ten Cassini VIMS radial mosaics acquired between october 2004 and january 2010. The dataset includes observations taken with solar phase running between 12° to 136° and elevation angle between -21° to +5°. These observations, after being reduced in spectrograms, e.g. 2D arrays containing the VIS-IR spectral (0.35-5.0 μm) and spatial (from 73.500 to 141.375 km) information, allow us a direct comparison of the derived spectral properties on a common spatial scale. Significant changes in VIS reddening, water ice abundance and grain sizes are observed across different rings radial regions. When observed at high solar phases, a remarkable increase of VIS reddening and water ice band depths is found, as a consequence of the presence of a red contaminant intimately mixed within water ice grains. Ring's particles temperature is retrieved by using the wavelength of the 3.6 μm continuum peak on reflectance spectra as a marker. For pure water ice the position of the peak, as measured in laboratory, shifts towards shorter wavelengths when temperature decreases, from about 3.65 μm at 123 K to about 3.55 μm at 88 K. When applied to VIMS rings observations, this method allow us to infer the average temperature across ring regions sampled with 400 km-wide radial bins. VIMS temperature radial profiles are compared with similar CIRS measurements acquired at the same time. We have found a substantial agreement between VIMS and CIRS results for the A and B ring while VIMS measures higher temperatures than CIRS across C ring and CD as a consequence of the lower optical depth and deviation from pure water ice composition. In summary, VIMS results show that 1) across C ring and CD the 3.6 μm peak wavelength is always higher than across B and A rings: C and CD are warmer than A and B rings; 2) when the solar elevation angle decreases to 0° (equinox) the peak's position shifts at shorter

  10. Mapping and interpretation of Sinlap crater on Titan using Cassini VIMS and RADAR data

    NASA Astrophysics Data System (ADS)

    Le Mouélic, Stéphane; Paillou, Philippe; Janssen, Michael A.; Barnes, Jason W.; Rodriguez, Sébastien; Sotin, Christophe; Brown, Robert H.; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Crapeau, Marc; Encrenaz, Pierre J.; Jaumann, Ralf; Geudtner, Dirk; Paganelli, Flora; Soderblom, Laurence; Tobie, Gabriel; Wall, Steve

    2008-04-01

    Only a few impact craters have been unambiguously detected on Titan by the Cassini-Huygens mission. Among these, Sinlap is the only one that has been observed both by the RADAR and VIMS instruments. This paper describes observations at centimeter and infrared wavelengths which provide complementary information about the composition, topography, and surface roughness. Several units appear in VIMS false color composites of band ratios in the Sinlap area, suggesting compositional heterogeneities. A bright pixel possibly related to a central peak does not show significant spectral variations, indicating either that the impact site was vertically homogeneous, or that this area has been recovered by homogeneous deposits. Both VIMS ratio images and dielectric constant measurements suggest the presence of an area enriched in water ice around the main ejecta blanket. Since the Ku-band SAR may see subsurface structures at the meter scale, the difference between infrared and SAR observations can be explained by the presence of a thin layer transparent to the radar. An analogy with terrestrial craters in Libya supports this interpretation. Finally, a tentative model describes the geological history of this area prior, during, and after the impact. It involves mainly the creation of ballistic ejecta and an expanding plume of vapor triggered by the impact, followed by the redeposition of icy spherules recondensed from this vapor plume blown downwind. Subsequent evolution is then driven by erosional processes and aeolian deposition.

  11. Mapping and interpretation of Sinlap crater on Titan using Cassini VIMS and RADAR data

    USGS Publications Warehouse

    Le, Mouelic S.; Paillou, P.; Janssen, M.A.; Barnes, J.W.; Rodriguez, S.; Sotin, C.; Brown, R.H.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Crapeau, M.; Encrenaz, P.J.; Jaumann, R.; Geudtner, D.; Paganelli, F.; Soderblom, L.; Tobie, G.; Wall, S.

    2008-01-01

    Only a few impact craters have been unambiguously detected on Titan by the Cassini-Huygens mission. Among these, Sinlap is the only one that has been observed both by the RADAR and VIMS instruments. This paper describes observations at centimeter and infrared wavelengths which provide complementary information about the composition, topography, and surface roughness. Several units appear in VIMS false color composites of band ratios in the Sinlap area, suggesting compositional heterogeneities. A bright pixel possibly related to a central peak does not show significant spectral variations, indicating either that the impact site was vertically homogeneous, or that this area has been recovered by homogeneous deposits. Both VIMS ratio images and dielectric constant measurements suggest the presence of an area enriched in water ice around the main ejecta blanket. Since the Ku-band SAR may see subsurface structures at the meter scale, the difference between infrared and SAR observations can be explained by the presence of a thin layer transparent to the radar. An analogy with terrestrial craters in Libya supports this interpretation. Finally, a tentative model describes the geological history of this area prior, during, and after the impact. It involves mainly the creation of ballistic ejecta and an expanding plume of vapor triggered by the impact, followed by the redeposition of icy spherules recondensed from this vapor plume blown downwind. Subsequent evolution is then driven by erosional processes and aeolian deposition. Copyright 2008 by the American Geophysical Union.

  12. A close look at Saturn's rings with Cassini VIMS

    USGS Publications Warehouse

    Nicholson, P.D.; Hedman, M.M.; Clark, R.N.; Showalter, M.R.; Cruikshank, D.P.; Cuzzi, J.N.; Filacchione, G.; Capaccioni, F.; Cerroni, P.; Hansen, G.B.; Sicardy, B.; Drossart, P.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Coradini, A.

    2008-01-01

    Soon after the Cassini-Huygens spacecraft entered orbit about Saturn on 1 July 2004, its Visual and Infrared Mapping Spectrometer obtained two continuous spectral scans across the rings, covering the wavelength range 0.35-5.1 ??m, at a spatial resolution of 15-25 km. The first scan covers the outer C and inner B rings, while the second covers the Cassini Division and the entire A ring. Comparisons of the VIMS radial reflectance profile at 1.08 ??m with similar profiles at a wavelength of 0.45 ??m assembled from Voyager images show very little change in ring structure over the intervening 24 years, with the exception of a few features already known to be noncircular. A model for single-scattering by a classical, many-particle-thick slab of material with normal optical depths derived from the Voyager photopolarimeter stellar occultation is found to provide an excellent fit to the observed VIMS reflectance profiles for the C ring and Cassini Division, and an acceptable fit for the inner B ring. The A ring deviates significantly from such a model, consistent with previous suggestions that this region may be closer to a monolayer. An additional complication here is the azimuthally-variable average optical depth associated with "self-gravity wakes" in this region and the fact that much of the A ring may be a mixture of almost opaque wakes and relatively transparent interwake zones. Consistently with previous studies, we find that the near-infrared spectra of all main ring regions are dominated by water ice, with a typical regolith grain radius of 5-20 ??m, while the steep decrease in visual reflectance shortward of 0.6 ??m is suggestive of an organic contaminant, perhaps tholin-like. Although no materials other than H2O ice have been identified with any certainty in the VIMS spectra of the rings, significant radial variations are seen in the strength of the water-ice absorption bands. Across the boundary between the C and B rings, over a radial range of ???7000 km, the

  13. Saturn's icy satellites investigated by Cassini-VIMS. IV. Daytime temperature maps

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; D'Aversa, Emiliano; Capaccioni, Fabrizio; Clark, Roger N.; Cruikshank, Dale P.; Ciarniello, Mauro; Cerroni, Priscilla; Bellucci, Giancarlo; Brown, Robert H.; Buratti, Bonnie J.; Nicholson, Phillip D.; Jaumann, Ralf; McCord, Thomas B.; Sotin, Christophe; Stephan, Katrin; Dalle Ore, Cristina M.

    2016-06-01

    The spectral position of the 3.6 μm continuum peak measured on Cassini-VIMS I/F spectra is used as a marker to infer the temperature of the regolith particles covering the surfaces of Saturn's icy satellites. This feature is characterizing the crystalline water ice spectrum which is the dominant compositional endmember of the satellites' surfaces. Laboratory measurements indicate that the position of the 3.6 μm peak of pure water ice is temperature-dependent, shifting towards shorter wavelengths when the sample is cooled, from about 3.65 μm at T=123 K to about 3.55 μm at T=88 K. A similar method was already applied to VIMS Saturn's rings mosaics to retrieve ring particles temperature (Filacchione, G., Ciarniello, M., Capaccioni, F., et al., 2014. Icarus, 241, 45-65). We report here about the daytime temperature variations observed on the icy satellites as derived from three different VIMS observation types: (a) a sample of 240 disk-integrated I/F observations of Saturn's regular satellites collected by VIMS during years 2004-2011 with solar phase in the 20°-40° range, corresponding to late morning-early afternoon local times. This dataset is suitable to exploit the temperature variations at hemispherical scale, resulting in average temperature T <88 K for Mimas, T ≪88 K for Enceladus, T <88 K for Tethys, T=98-118 K for Dione, T=108-128 K for Rhea, T=118-128 K for Hyperion, T=128-148 and T > 168 K for Iapetus' trailing and leading hemispheres, respectively. A typical ±5 K uncertainty is associated to the temperature retrieval. On Tethys and Dione, for which observations on both leading and trailing hemispheres are available, in average daytime temperatures higher of about 10 K on the trailing than on the leading hemisphere are inferred. (b) Satellites disk-resolved observations taken at 20-40 km pixel-1 resolution are suitable to map daytime temperature variations across surfaces' features, such as Enceladus' tiger stripes and Tethys' equatorial dark lens

  14. Cassini VIMS Spectra of the Thermal Emission from Hot Spots Along Enceladus South Pole Fissures

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Cassini VIMS Team

    2016-10-01

    Most of the south pole fissure region has not been directly illuminated by sunlight since the sub-solar point moved into the northern hemisphere in 2009, thereby eliminating the background of reflected sunlight at VIMS wavelengths and making the fissure thermal emission readily measureable. Since then, VIMS has measured spectra of at least 11 hot spots along the fissures. Most of these measurements were acquired in ride-along mode with CIRS as the prime instrument. During at least 2 encounters, VIMS and CIRS acquired simultaneous or near-simultaneous spectra of the same fissure location. VIMS spectra include multiple hot spots along Damascus, Baghdad, Cairo, and a likely hot spot on Alexandria.All of the VIMS spectra examined to date are consistent with this scenario of a self-regulating fissure maximum T~200 K with brighter VIMS emissions corresponding to fissures up to ~20 m wide. Emission from the warm fissure interior walls dominate the VIMS spectra with <15% contributed by conductive heating of the adjacent terrain at VIMS wavelengths.CIRS spectra report slightly cooler T's due to CIRS increased sensitivity to lower T emission at longer wavelengths and averaging over contributions from both the hottest and cooler areas. Combined analysis of the CIRS and VIMS spectra spanning 3 to 500 micron wavelengths promises to reveal the distribution of [T, area] near the fissures that cannot be spatially resolved. This [T, area] distribution holds the key to understanding how heat is transferred to the surface within a few 100 m of the fissures.The VIMS-detected emission is concentrated in localized hot spots along the fissures and does not seem to be distributed continuously along them. CIRS spectra suggest a more continuous distribution of the emission along the fissure length. Jets locations also are distributed along the fissure length and it appears that the VIMS-detected hot spots in general correlate with jet locations, but not all of the jet locations have been

  15. Europa's Opposition Surge in the Near-Infrared: Interpreting Disk-Integrated Observations by Cassini VIMS

    NASA Astrophysics Data System (ADS)

    Simonelli, D. P.; Buratti, B. J.

    2003-05-01

    Observations of Europa's opposition surge by Cassini VIMS, presented at last year's DPS, have now been modeled with the commonly used Hapke photometric function. The VIMS dataset emphasizes observations at 16 phase angles from 0.4 to 0.6 deg---the first time the < 1 deg phase ``heart" of Europa's opposition surge has been observed in the near-IR. This dataset also provides a unique opportunity to examine how the surge is affected by changes in wavelength and albedo: at VIMS wavelengths of 0.91, 1.73, and 2.25 microns, the geometric albedo of Europa is 0.81, 0.33, and 0.18 respectively. Despite this factor-of-four albedo range, however, the slope of Europa's phase curve at < 1 deg phase is similar at all three wavelengths (to within error bars) and this common slope is similar to the phase coefficient seen in visible observations of Europa. Two competing models for the opposition surge's physical cause are the Shadow Hiding Opposition Effect (SHOE) and Coherent Backscatter Effect (COBE). Because of sparse VIMS phase coverage, it's not possible to constrain all the surge parameters at once in a Hapke function that has both SHOE and COBE; accordingly, we performed separate Hapke fits for SHOE-only and COBE-only surges. At 2.25 microns, where VIMS data are somewhat noisy, both types of surges can mimic the slope of the VIMS phase curve at < 1 deg phase. At 0.91 and 1.73 microns, however---where VIMS data are ``cleaner"---COBE does a noticeably poorer job than SHOE of matching the VIMS phase coefficient at < 1 deg phase; in particular, the best COBE fit insists on having a steeper phase-curve slope than the data. This suggests---without being conclusive---that COBE is less likely than SHOE to be the cause of Europa's near-IR opposition surge.

  16. Simultaneous Cartography of Aerosol Opacity and Surface Albedo of Titan by the Massive Inversion of the Cassini/VIMS Dataset

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Maltagliati, L.; Sotin, C.; Rannou, P.; Cornet, T.; Hirtzig, M.; Appéré, T.; Solomonidou, A.; Le Mouelic, S.; Coustenis, A.; Brown, R. H.

    2015-12-01

    Mapping Titan's surface albedo is a necessary step to give reliable constraints on its composition. However, surface albedo maps of Titan, especially over large regions, are still very rare, the surface windows being strongly affected by atmospheric effects (absorption, scattering). A full radiative transfer model is an essential tool to remove these effects, but too time-consuming to treat systematically the ~40000 hyperspectral images VIMS acquired since the beginning of the mission. We developed a massive inversion of VIMS data based on lookup tables computed from a state-of-the-art radiative transfer model (Hirtzig et al. 2013), updated with new aerosol properties coming from our analysis of the Emission Phase Function observation acquired recently by VIMS. Once the physical properties of gases, aerosols and surface are fixed, the lookup tables are built for the remaining free parameters: the incidence, emergence and azimuth angles, given by navigation; and two products (the aerosol opacity and the surface albedo at all wavelengths). The lookup table grid was carefully selected after thorough testing. The data inversion on these pre-computed spectra (opportunely interpolated) is more than 1000 times faster than recalling the full radiative transfer at each minimization step. We present here the results from selected flybys. We invert mosaics composed by couples of flybys observing the same area at two different times. The composite albedo maps do not show significant discontinuities in any of the surface windows, suggesting a robust correction of the effects of the geometry (and thus the aerosols) on the observations. Maps of aerosol and albedo uncertainties are also provided, with the absolute error on the albedo being approximately between 1 and 3% (depending on the surface window considered). We are thus able to provide for the first time ever reliable surface albedo maps at pixel scale for the whole VIMS spectral range.

  17. Kelvin Absolute Temperature Scale Identified as Length Scale and Related to de Broglie Thermal Wavelength

    NASA Astrophysics Data System (ADS)

    Sohrab, Siavash

    Thermodynamic equilibrium between matter and radiation leads to de Broglie wavelength λdβ = h /mβvrβ and frequency νdβ = k /mβvrβ of matter waves and stochastic definitions of Planck h =hk =mk <λrk > c and Boltzmann k =kk =mk <νrk > c constants, λrkνrk = c , that respectively relate to spatial (λ) and temporal (ν) aspects of vacuum fluctuations. Photon massmk =√{ hk /c3 } , amu =√{ hkc } = 1 /No , and universal gas constant Ro =No k =√{ k / hc } result in internal Uk = Nhνrk = Nmkc2 = 3 Nmkvmpk2 = 3 NkT and potential pV = uN\\vcirc / 3 = N\\ucirc / 3 = NkT energy of photon gas in Casimir vacuum such that H = TS = 4 NkT . Therefore, Kelvin absolute thermodynamic temperature scale [degree K] is identified as length scale [meter] and related to most probable wavelength and de Broglie thermal wavelength as Tβ =λmpβ =λdβ / 3 . Parallel to Wien displacement law obtained from Planck distribution, the displacement law λwS T =c2 /√{ 3} is obtained from Maxwell -Boltzmann distribution of speed of ``photon clusters''. The propagation speeds of sound waves in ideal gas versus light waves in photon gas are described in terms of vrβ in harmony with perceptions of Huygens. Newton formula for speed of long waves in canals √{ p / ρ } is modified to √{ gh } =√{ γp / ρ } in accordance with adiabatic theory of Laplace.

  18. Composition of Titan's surface from Cassini VIMS

    USGS Publications Warehouse

    McCord, T.B.; Hansen, G.B.; Buratti, B.J.; Clark, R.N.; Cruikshank, D.P.; D'Aversa, E.; Griffith, C.A.; Baines, E.K.H.; Brown, R.H.; Dalle, Ore C.M.; Filacchione, G.; Formisano, V.; Hibbitts, C.A.; Jaumann, R.; Lunine, J.I.; Nelson, R.M.; Sotin, C.

    2006-01-01

    Titan's bulk density along with Solar System formation models indicates considerable water as well as silicates as its major constituents. This satellite's dense atmosphere of nitrogen with methane is unique. Deposits or even oceans of organic compounds have been suggested to exist on Titan's solid surface due to UV-induced photochemistry in the atmosphere. Thus, the composition of the surface is a major piece of evidence needed to determine Titan's history. However, studies of the surface are hindered by the thick, absorbing, hazy and in some places cloudy atmosphere. Ground-based telescope investigations of the integral disk of Titan attempted to observe the surface albedo in spectral windows between methane absorptions by calculating and removing the haze effects. Their results were reported to be consistent with water ice on the surface that is contaminated with a small amount of dark material, perhaps organic material like tholin. We analyze here the recent Cassini Mission's visual and infrared mapping spectrometer (VIMS) observations that resolve regions on Titan. VIMS is able to see surface features and shows that there are spectral and therefore likely compositional units. By several methods, spectral albedo estimates within methane absorption windows between 0.75 and 5 ??m were obtained for different surface units using VIMS image cubes from the Cassini-Huygens Titan Ta encounter. Of the spots studied, there appears to be two compositional classes present that are associated with the lower albedo and the higher albedo materials, with some variety among the brighter regions. These were compared with spectra of several different candidate materials. Our results show that the spectrum of water ice contaminated with a darker material matches the reflectance of the lower albedo Titan regions if the spectral slope from 2.71 to 2.79 ??m in the poorly understood 2.8-??m methane window is ignored. The spectra for brighter regions are not matched by the spectrum of

  19. Dominant Wavelength of Small-Scale Folds Between Enceladus' South Polar Tiger Stripes

    NASA Astrophysics Data System (ADS)

    Preuss, L. J.; Barr, A. C.

    2010-03-01

    High-resolution images of Enceladus' south polar terrain reveal regions of small-scale folds between Damascus and Baghdad sulci. We will present the results of a systematic study of the folding wavelength using Fourier transform methods.

  20. Focus for VIM Members: Materials to Learn By

    ERIC Educational Resources Information Center

    American Vocational Journal, 1978

    1978-01-01

    A brief discussion and initiation into the Vocational Instructional Materials (VIM) Section of the American Vocational Association. VIM's activities at the annual vocational convention are briefly sketched. (SH)

  1. VIM: The Communication Link for Professionals

    ERIC Educational Resources Information Center

    Jensen, Arthur

    1978-01-01

    Describes the organization and operating policies of the Vocational Instructional Materials Section (VIM) in the New and Related Services Division of the American Vocational Association (AVA). VIM was established in 1969 to give organization and visibility to instructional materials development personnel within AVA. (MF)

  2. Wavelength-Scale Structures as Extremely High Haze Films for Efficient Polymer Solar Cells.

    PubMed

    Ham, Juyoung; Dong, Wan Jae; Jung, Gwan Ho; Lee, Jong-Lam

    2016-03-01

    Wavelength-scale inverted pyramid structures with low reflectance and excellent haze have been designed for application to polymer solar cells (PSCs). The wavelength-scale structured haze films are fabricated on the back surface of glass without damages to organic active layer by using a soft lithographic technique with etched GaN molds. With a rigorous coupled-wave analysis of optical modeling, we find the shift of resonance peaks with the increase of pattern's diameter. Wavelength-scale structures could provide the number of resonances at the long wavelength spectrum (λ = 650-800 nm), yielding enhancement of power conversion efficiency (PCE) in the PSCs. Compared with a flat device (PCE = 7.12%, Jsc = 15.6 mA/cm(2)), improved PCE of 8.41% is achieved in a haze film, which is mainly due to the increased short circuit current density (Jsc) of 17.5 mA/cm(2). Hence, it opens up exciting opportunities for a variety of PSCs with wavelength-scale structures to further improve performance, simplify complicated process, and reduce costs.

  3. Wavelength-Scale Structures as Extremely High Haze Films for Efficient Polymer Solar Cells.

    PubMed

    Ham, Juyoung; Dong, Wan Jae; Jung, Gwan Ho; Lee, Jong-Lam

    2016-03-01

    Wavelength-scale inverted pyramid structures with low reflectance and excellent haze have been designed for application to polymer solar cells (PSCs). The wavelength-scale structured haze films are fabricated on the back surface of glass without damages to organic active layer by using a soft lithographic technique with etched GaN molds. With a rigorous coupled-wave analysis of optical modeling, we find the shift of resonance peaks with the increase of pattern's diameter. Wavelength-scale structures could provide the number of resonances at the long wavelength spectrum (λ = 650-800 nm), yielding enhancement of power conversion efficiency (PCE) in the PSCs. Compared with a flat device (PCE = 7.12%, Jsc = 15.6 mA/cm(2)), improved PCE of 8.41% is achieved in a haze film, which is mainly due to the increased short circuit current density (Jsc) of 17.5 mA/cm(2). Hence, it opens up exciting opportunities for a variety of PSCs with wavelength-scale structures to further improve performance, simplify complicated process, and reduce costs. PMID:26901630

  4. Wavelength-selective and anisotropic light-diffusing scale on the wing of the Morpho butterfly.

    PubMed Central

    Yoshioka, Shinya; Kinoshita, Shuichi

    2004-01-01

    We have found that cover scales on the wing of the butterfly Morpho didius possess specially designed microscopic structures for wavelength-selective reflection and contribute considerably to the brilliant blue colour of the wing. In addition, the cover scale functions as an anisotropic optical diffuser which diffuses light only in one plane, while it makes the range of reflection narrower in the orthogonal plane. The quantitative analyses for the wavelength-selection mechanism and the peculiar optical diffuser are given and the role of such a special optical effect is discussed from physical and biological viewpoints. PMID:15156915

  5. Small particles and self-gravity wakes in Saturn's rings from UVIS and VIMS stellar occultations

    NASA Astrophysics Data System (ADS)

    Jerousek, Richard G.; Colwell, Joshua E.; Esposito, Larry W.; Nicholson, Philip D.; Hedman, Matthew M.

    2016-11-01

    The distribution of particle sizes in Saturn's rings roughly follows a truncated inverse power-law. Though it is well known that differential optical depths provide a way to probe the parameters of size distribution (i.e. Zebker et al. [1985] Icarus, 64, 531-548), the technique is complicated by the presence of self-gravity wakes which introduce a geometric dependence to the observed optical depth. Here we present a method of extracting information about the size distribution of the particles in the gaps between the self-gravity wakes. The Cassini Visual and Infrared Mapping Spectrometer (VIMS) occultations measure starlight at an effective wavelength of 2.9 μm falling onto a single pixel with angular dimensions 0.25 mrad × 0.5 mrad while Cassini Ultraviolet Imaging Spectrograph (UVIS) occultations measure starlight at a much smaller effective wavelength of 0.15 μm and over a field of view with larger angular dimensions of 6.0 mrad × 6.4 mrad. Starlight diffracted out of the VIMS pixel by particles smaller than 1.22λVIMS/2θ ∼8.86 mm, is not replaced by neighboring particles, while the UVIS instrument, with its larger field of view and smaller effective wavelength, collects all of the light diffracted by particles larger than 1.22λVIMS/2θ ∼0.025 mm. Consequently, measurements by VIMS overstate the optical depth in regions where sub-centimeter-sized particles are present. Using the rectangular cross section wake model of (Colwell et al. [2006], Geophys. Res. Lett., 33, L07201) and (Colwell et al. [2007] Icarus, 190, 127-144) with a new parameter to represent the excess VIMS optical depth not seen by UVIS, we combine VIMS and UVIS occultations for the first time for particle size analysis. We find a significant fraction of sub-cm particles only in the outermost portion of the A ring, and in the B1 region of the B ring. In the Trans-Encke region, we find a trend of increasing abundance of sub-cm particles as the outer edge of the A Ring is approached

  6. Europa's opposition surge in the near-infrared: interpreting disk-integrated observations by Cassini VIMS

    NASA Astrophysics Data System (ADS)

    Simonelli, Damon P.; Buratti, Bonnie J.

    2004-11-01

    Near-infrared observations of Europa's disk-integrated opposition surge by Cassini VIMS, first published in Fig. 4 of Brown et al. (2003, Icarus, 164, 461), have now been modeled with the commonly used Hapke photometric function. The VIMS data set emphasizes observations at 16 solar phase angles from 0.4° to 0.6°—the first time the <1° phase "heart" of Europa's opposition surge has been observed this well in the near-IR. This data set also provides a unique opportunity to examine how the surge is affected by changes in wavelength and albedo: at VIMS wavelengths of 0.91, 1.73, and 2.25 μm, the geometric albedo of Europa is 0.81, 0.33, and 0.18, respectively. Despite this factor-of-four albedo range, however, the slope of Europa's phase curve at <1° phase is similar at all three wavelengths (to within the error bars) and this common slope is similar to the phase coefficient seen in visible-light observations of Europa. The two components of the opposition surge—involving different models of the physical cause of the surge—are the Shadow Hiding Opposition Effect (SHOE) and the Coherent Backscatter Opposition Effect (CBOE). Because of sparse VIMS phase coverage, it is not possible to constrain all the surge parameters at once in a Hapke function that has both SHOE and CBOE; accordingly, we performed separate Hapke fits for SHOE-only and CBOE-only surges. At 2.25 μm, where VIMS data are somewhat noisy, both types of surges can mimic the slope of the VIMS phase curve at <1° phase. At 0.91 and 1.73 μm, however—where VIMS data are "cleaner"—CBOE does a noticeably poorer job than SHOE of matching the VIMS phase coefficient at <1° phase; in particular, the best CBOE fit insists on having a steeper phase-curve slope than the data. This discrepancy suggests that Europa's near-IR opposition surge cannot be explained by CBOE alone and must have a significant SHOE component, even at wavelengths where Europa is bright.

  7. Novel VIM Metallo-β-Lactamase Variant, VIM-24, from a Klebsiella pneumoniae Isolate from Colombia▿

    PubMed Central

    Montealegre, Maria Camila; Correa, Adriana; Briceño, David F.; Rosas, Natalia C.; De La Cadena, Elsa; Ruiz, Sory J.; Mojica, Maria F.; Camargo, Ruben Dario; Zuluaga, Ivan; Marin, Adriana; Quinn, John P.; Villegas, Maria Virginia

    2011-01-01

    We report the emergence of a novel VIM variant (VIM-24) in a Klebsiella pneumoniae isolate in Colombia. The isolate displays MICs for carbapenems below the resistance breakpoints, posing a real challenge for its detection. The blaVIM-24 gene was located within a class 1 integron carried on a large plasmid. Further studies are needed to clarify its epidemiological and clinical impact. PMID:21282438

  8. Projects To Probe Titan's Surface Composition and Development of Atmospheric Removal Models for Cassini VIMS Data

    NASA Astrophysics Data System (ADS)

    Pitman, K. M.; Buratti, B. J.; Baines, K. H.; West, R. A.; Wolff, M. J.; Brown, R. H.

    2007-05-01

    In this work, we will describe recent projects performed by our group at the Jet Propulsion Laboratory, California Institute of Technology involving I/F data of Titan's surface acquired by Cassini's Visual and Infrared Mapping Spectrometer (VIMS), including the next stage of development of methods to de-gas and de-fog VIMS images. VIMS I/F spectra include contributions from both surface and atmospheric signal; therefore, current spectral data analysis necessarily focuses on portions of VIMS I/F spectra where atmospheric methane and scattering by haze is at a minimum. However, atmospheric opacity clears enough between wavelengths of 1 and 2 microns to provide strong potential to view complex landforms if a proper atmospheric correction can be applied. Plane- parallel radiative transfer (RT) correction methods have been used successfully in surface-atmospheric separation retrievals for Mars and offer some utility for VIMS observations of Titan that are away from the limb. In a previous work (Pitman et al. 2007, LPSC XXXVIII, p. 1164), we determined which inputs to radiative transfer models must be updated, given results from recent meetings and literature, and evaluated two plane-parallel RT models (adding-doubling, discrete ordinates) to determine which is more easily customized for surface- atmospheric separation of Titan. In this work, we report our progress on replacing Voyager with Cassini-Huygens inputs and how these models currently compare. Work performed under contract to NASA and by appointment to the NASA Postdoctoral Program (ORAU).

  9. About the Portuguese VIM3 version

    NASA Astrophysics Data System (ADS)

    Pellegrino, O.; Cruz, A.; Oliveira, J. C.; Filipe, E.

    2015-02-01

    For the first time, a unique Portuguese version of the International Vocabulary of Metrology (VIM) was organized and published by the National Metrology Institutes (NMIs) of Portugal and Brazil. This challenge could be met thanks to the experiences of the respective translations of the previous editions of the VIM and to the new Orthographic Agreement (AO) of the Portuguese speaking countries. After a brief historical review of the VIMs and their Portuguese versions, this communication aims to display the main steps that led to the final joint translation. Advantage was taken of this 3rd edition and of the AO to update the Portuguese multiplicative prefix writing "kilo" in coherence with the respective symbol "k". By way of answer to the questions raised by the recent edition of the VIM (VIM3) that stresses on the concepts associated to the terms, some suggestions are proposed and inconsistencies are identified, in order to facilitate the understanding and the dissemination of the document. These few suggestions for the next edition of the VIM also intended to standardize the terminology found in normative texts of different scientific fields which unfortunately does not necessarily tend to be consistent between them.

  10. Titan's haze as seen by VIMS during solar occultation observations

    NASA Astrophysics Data System (ADS)

    Sotin, Christophe; Lawrence, Ken; Xu, Fang; West, Robert; Brown, Robert; Baines, Kevin; Buratti, Bonnie; Clark, Roger; Micholson, Phil

    2016-06-01

    This study describe solar occultation observations of Titan's atmosphere by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. These observations include two recent observations made in the last few months. The solar occultation observations have been made at different latitudes and seasons, which allows us to investigate the variability of the density profile of aerosols. We present the line curves in the different atmospheric windows, and the data processing and the inversion method to retrieve vertical density profile. This unique data set provides information on Titan's opacity in the atmospheric windows, which is important to retrieve the surface properties. It also provides information on the cross-subsection of the aerosols as a function of wavelength in the wavelength range 1 to 5 micron.

  11. Investigation of Titan's surface and atmosphere photometric functions using the Cassini/VIMS instrument

    NASA Astrophysics Data System (ADS)

    Cornet, Thomas; Altobelli, Nicolas; Rodriguez, Sébastien; Maltagliati, Luca; Le Mouélic, Stéphane; Sotin, Christophe; Brown, Robert; Barnes, Jason; Buratti, Bonnie; Baines, Kevin; Clark, Roger; Nicholson, Phillip

    2015-04-01

    After 106 flybys spread over 10 years, the Cassini Visual and Infrared Mapping Spectrometer (VIMS) instrument acquired 33151 hyperspectral cubes pointing at the surface of Titan on the dayside. Despite this huge amount of data available for surface studies, and due to the strong influence of the atmosphere (methane absorption and haze scattering), Titan's surface is only visible with VIMS in 7 spectral atmospheric windows centred at 0.93, 1.08, 1.27, 1.59, 2.01, 2.7-2.8 and 5 microns. Atmospheric scattering and absorption effects dominate Titan's spectrum at wavelengths shorter than 3 microns, while the 5 micron window, almost insensitive to the haze scattering, only presents a reduced atmospheric absorption contribution to the signal recorded by VIMS. In all cases, the recorded I/F represents an apparent albedo, which depends on the atmospheric contributions and the surface photometry at each wavelength. We therefore aim to determine real albedo values for Titan's surface by finding photometric functions for the surface and the atmosphere that could be used as a basis for empirical corrections or Radiative Transfer calculations. After updating the navigation of the VIMS archive, we decomposed the entire VIMS data set into a MySQL relational database gathering the viewing geometry, location, time (season) and I/F (for pure atmosphere and surface-atmosphere images) for each pixel of the 33151 individual VIMS cubes. We then isolated all the VIMS pixels where Titan's surface has been repeatedly imaged at low phase angles (< 20 degrees) in order to characterize phase curves for the surface at 5 microns and for the atmosphere. Among these, the T88 flyby appears noteworthy, with a "Emergence-Phase Function (EPF)"-type observation: 25 cubes acquired during the same flyby, over the same area (close to Tortola Facula, in relatively dark terrains), at a constant incidence and with varying emergence and phase (from 0 to 60 degrees) angles. The data clearly exhibit an increase

  12. Biochemical Characterization of VIM-39, a VIM-1-Like Metallo-β-Lactamase Variant from a Multidrug-Resistant Klebsiella pneumoniae Isolate from Greece

    PubMed Central

    Pollini, Simona; De Luca, Filomena; Rossolini, Gian Maria; Docquier, Jean-Denis; Hrabák, Jaroslav

    2015-01-01

    VIM-39, a VIM-1-like metallo-β-lactamase variant (VIM-1 Thr33Ala His224Leu) was identified in a clinical isolate of Klebsiella pneumoniae belonging to sequence type 147. VIM-39 hydrolyzed ampicillin, cephalothin, and imipenem more efficiently than did VIM-1 and VIM-26 (a VIM-1 variant with the His224Leu substitution) because of higher turnover rates. PMID:26369975

  13. Stability study of standards used for calibration of the spectrophotometer wavelength scale

    NASA Astrophysics Data System (ADS)

    Debossan, L. F.; Carvalho, E. M. S.; Souza, M. A.; Gomes, J. F. S.

    2016-07-01

    The calibration of spectrophotometers is a procedure recommended by international standards to provide quality assurance of results and traceability. Due to its intrinsic properties, holmium oxide filters are indicated as reference standards for calibrating the wavelength scale of such equipment. This paper presents a study aiming to assess the repeatability and drift of holmium oxide standard filters calibrated in the Radiometry and Photometry Laboratory (Laraf) of Inmetro in order to verify their stability.

  14. Crossover scaling of wavelength selection in directional solidification of binary alloys.

    PubMed

    Greenwood, Michael; Haataja, Mikko; Provatas, And Nikolas

    2004-12-10

    We simulate cellular and dendritic growth in directional solidification in dilute binary alloys using a phase-field model solved with adaptive-mesh refinement. The spacing of primary branches is examined for a wide range of thermal gradients and alloy compositions and is found to undergo a maximum as a function of pulling velocity, in agreement with experimental observations. We demonstrate that wavelength selection is unambiguously described by a nontrivial crossover scaling function from the emergence of cellular growth to the onset of dendritic fingers. This result is further validated using published experimental data, which obeys the same scaling function.

  15. Hapke modeling of Rhea surface properties through Cassini-VIMS spectra

    USGS Publications Warehouse

    Ciarniello, M.; Capaccioni, F.; Filacchione, G.; Clark, R.N.; Cruikshank, D.P.; Cerroni, P.; Coradini, A.; Brown, R.H.; Buratti, B.J.; Tosi, F.; Stephan, K.

    2011-01-01

    The surface properties of the icy bodies in the saturnian system have been investigated by means of the Cassini-VIMS (Visual Infrared Mapping Spectrometer) hyperspectral imager which operates in the 0.35-5.1. ??m wavelength range. In particular, we have analyzed 111 full disk hyperspectral images of Rhea ranging in solar phase between 0.08?? and 109.8??. These data have been previously analyzed by Filacchione et al. (Filacchione, G. et al. [2007]. Icarus 186, 259-290; Filacchione, G. et al. [2010]. Icarus 206, 507-523) to study, adopting various "spectral indicators" (such as spectral slopes, band depth, and continuum level), the relations among various saturnian satellites. As a further step we proceed in this paper to a quantitative evaluation of the physical parameters determining the spectrophotometric properties of Rhea's surface. To do this we have applied Hapke (Hapke, B. [1993]. Theory of Reflectance and Emittance Spectroscopy, Topics in Remote Sensing: 3 Springer, Berlin) IMSA model (Isotropic Multiple Scattering Approximation) which allow us to model the phase function at VIS-IR (visible-infrared) wavelengths as well as the spectra taking into account various types of mixtures of surface materials. Thanks to this method we have been able to constrain the size of water ice particles covering the surface, the amount of organic contaminants, the large scale surface roughness and the opposition effect surge. From our analysis it appears that wavelength dependent parameters, e.g. opposition surge width (h) and single-particle phase function parameters (b,. v), are strongly correlated to the estimated single-scattering albedo of particles. For Rhea the best fit solution is obtained by assuming: (1) an intraparticle mixture of crystalline water ice and a small amount (0.4%) of Triton tholin; (2) a monodisperse grain size distribution having a particle diameter am= 38. ??m; and (3) a surface roughness parameter value of 33??. The study of phase function shows

  16. Cassini Vims Observations Of Thermal Emission From The Warmest 'Tiger Stripes' Near The South Pole On Enceladus

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, B. J.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.; Hedman, M. M.; Sotin, C.; Cruikshank, D. P.; Baines, K. H.; Lawrence, K. J.; Spencer, J. R.; Blackburn, D.

    2012-10-01

    The discovery and continuing investigation of the long linear fissures near Enceladus’ south pole is a major highlight of the Cassini mission to Saturn. Known as the ‘tiger stripes’, these fissures are the source of water dominated plumes and extensive thermal emission (Spencer et al, 2006; Porco et al, 2006). This paper presents new observational constraints on the highest temperature component of the tiger stripes thermal emission using VIMS (Visible and Infrared Mapping Spectrometer) spectra. Because VIMS detects the thermal emission at 4 to 5 micrometer wavelengths, VIMS is sensitive to the rising edge of Planck function for temperatures near 200 K, making the new VIMS spectra complementary to the CIRS observations acquired at longer wavelengths. Although the thermal emission spectra of the hottest areas is only a small piece of the Enceladus and tiger stripe puzzle, it is an important missing piece that we will use to model how and where the detected heat is generated and the physical processes that transport the heat to the observable surface. Our first definitive detection of thermal emission from Baghdad Sulcus was reported in Blackburn et al (LPSC 2012) from VIMS data acquired during E11 (August 2010). Due to seasonal change during the mission, the Enceladus S. pole region has entered the perpetual winter night and reflected sunlight does not interfere with VIMS measurements of the faint thermal emission as it did early in the mission. During the 75 km altitude targeted encounter E18 (April 2012), VIMS acquired a 2 minute long sequence of 25 ms integration time spectra through a single high resolution pixel as Cassini passed over the South pole. The resulting data has the best spatial resolution of the thermal emission acquired to date. This work was supported in part by a grant from NASA’s Outer Planets Research Program.

  17. Light in materials with periodic gain-loss modulation on a wavelength scale

    SciTech Connect

    Botey, Muriel; Herrero, Ramon; Staliunas, Kestutis

    2010-07-15

    We analyze light-wave dynamics in artificial materials characterized by periodically modulated gain or loss on the wavelength scale. The study of the temporal dispersion in one-dimensionally modulated materials predicts mode-locked states and superluminal light propagation regimes in the parameter regions close to the locking regions. The study of spatial dispersion for a two-dimensional gain-loss modulation predicts nontrivial beam propagation effects such as self-collimation, angle-sensitive gain, and negative diffraction in such gain-loss-modulated materials.

  18. Cassini VIMS observations of the Galilean satellites including the VIMS calibration procedure

    USGS Publications Warehouse

    McCord, T.B.; Coradini, A.; Hibbitts, C.A.; Capaccioni, F.; Hansen, G.B.; Filacchione, G.; Clark, R.N.; Cerroni, P.; Brown, R.H.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Buratti, B.J.; Bussoletti, E.; Combes, M.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Jaumann, R.; Langevin, Y.; Matson, D.L.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.

    2004-01-01

    The Visual and Infrared Mapping Spectrometer (VIMS) observed the Galilean satellites during the Cassini spacecraft's 2000/2001 flyby of Jupiter, providing compositional and thermal information about their surfaces. The Cassini spacecraft approached the jovian system no closer than about 126 Jupiter radii, about 9 million kilometers, at a phase angle of < 90 ??, resulting in only sub-pixel observations by VIMS of the Galilean satellites. Nevertheless, most of the spectral features discovered by the Near Infrared Mapping Spectrometer (NIMS) aboard the Galileo spacecraft during more than four years of observations have been identified in the VIMS data analyzed so far, including a possible 13C absorption. In addition, VIMS made observations in the visible part of the spectrum and at several new phase angles for all the Galilean satellites and the calculated phase functions are presented. In the process of analyzing these data, the VIMS radiometric and spectral calibrations were better determined in preparation for entry into the Saturn system. Treatment of these data is presented as an example of the VIMS data reduction, calibration and analysis process and a detailed explanation is given of the calibration process applied to the Jupiter data. ?? 2004 Elsevier Inc. All rights reserved.

  19. Mimas: Preliminary Evidence For Amorphous Water Ice From VIMS (Invited)

    NASA Astrophysics Data System (ADS)

    Cruikshank, D. P.; Marzo, G.; Pinilla-Alonso, N.; Roush, T. L.; Mastrapa, R. M.; Dalle Ore, C. M.; Buratti, B. J.; Stephan, K.; Brown, R. H.; Baines, K. H.; Clark, R. N.; Nicholson, P. D.; Sotin, C.; Cassini Vims Team

    2010-12-01

    We have conducted a statistical clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn’s satellite Mimas. Seven VIMS cubes were geometrically projected and re-sampled to a common spatial resolution. The clustering technique consists of a partitioning algorithm coupled to a criterion that prevents sub-optimal solutions and tests for the influence of random noise in the measurements. The clustering technique is agnostic about the meaning of the clusters, and scientific interpretation requires their a posteriori evaluation. The preliminary results yielded five clusters, demonstrating that spectral variability across Mimas’ surface is statistically significant. The ratios of the means calculated for each of the clusters show structure within the 1.6-µm water ice band, as well as the shape and the central wavelength of the strong ice band at 2 µm, that map spatially in patterns apparently related to the topography of Mimas, in particular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similarities (band shape and central wavelength) with lab spectra of amorphous and crystalline H2O ice (3) that are suggestive of the presence of an amorphous (or “disordered”) ice component in certain regions of Mimas, notably on the central peak of Herschel, on the crater floor, and in faults surrounding the crater. Mimas is too warm to sustain H2O ice in a possibly original amorphous form for the great age of the surface, and its appearance may represent a mixture of both ice phases, or perhaps a layer of disordered ice on a base of crystalline ice. Another possible occurrence of non-crystalline ice appears southwest of Herschel, close to the south pole. (1) Marzo, G. A. et al. J. Geophys. Res. 111, E03002, 2006. (2) Marzo, G. A. et al. J. Geophys. Res. 113, E12009, 2008. (3) Mastrapa, R. M., et al. Astrophys. J. 701, 1347-1356, 2009.

  20. Cassini-VIMS temperature maps of Saturn's satellites

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Tosi, F.; D'Aversa, E.; Clark, R. N.; Brown, R. H.; Buratti, B. J.; Cruikshank, D. P.; Dalle Ore, M. C.; Scipioni, F.; Cerroni, P.

    The spectral position of the 3.6 mu m continuum peak measured on Cassini-VIMS reflectance spectra is used to infer the temperature of the regolith particles covering the surfaces of Saturn's icy satellites. Laboratory measurements by \\cite{Clark2012} have shown that 3.6 mu m peak for pure crystalline water ice particles shifts towards shorter wavelengths when the sample is cooled, moving from about 3.65 mu m at T=123 K to about 3.55 mu m at T=88 K. A similar trend is observed also in the imaginary part (k) of the refractive index of water ice when the sample is cooled from T=140 K to 20 K \\citep{Mastrapa2009}. Since water ice is the dominant endmember on Saturn's satellites surfaces \\citep{Filacchione2012}, the measurement of the wavelength at which the 3.6 mu m reflectance peak occurs can be considered as a temperature indicator. We report about temperature maps of Mimas, Enceladus, Tethys, Dione and Rhea derived by applying this method to Cassini-VIMS data taken at spatial resolution of 20-40 km/pixel. These maps allow us to correlate the temperature distribution with solar illumination conditions and with geological features. On average Enceladus' midlatitudes regions appear at T<100 K while the south pole tiger-stripes active area shows a thermal emission at T>115 K. Tethys' and Mimas' equatorial lenses show significant thermal anomalies: despite these features have low visible albedo they appear more cold than the surrounding mid-latitude regions as a consequence of a much higher thermal inertia. On Mimas, Hershel crater's floor appears warmer (T>115 K) than the adjacent equatorial lens area (T<110 K). Finally, Dione's analysis evidences lower temperature across the bright wispy terrains than the nearby low albedo areas.

  1. Organized chromophoric assemblies for nonlinear optical materials: towards (sub)wavelength scale architectures.

    PubMed

    Xu, Jialiang; Semin, Sergey; Rasing, Theo; Rowan, Alan E

    2015-03-01

    Photonic circuits are expected to greatly contribute to the next generation of integrated chips, as electronic integrated circuits become confronted with bottlenecks such as heat generation and bandwidth limitations. One of the main challenges for the state-of-the-art photonic circuits lies in the development of optical materials with high nonlinear optical (NLO) susceptibilities, in particular in the wavelength and subwavelength dimensions which are compatible with on-chip technologies. In this review, the varied approaches to micro-/nanosized NLO materials based on building blocks of bio- and biomimetic molecules, as well as synthetic D-π-A chromophores, have been categorized as supramolecular self-assemblies, molecular scaffolds, and external force directed assemblies. Such molecular and supramolecular NLO materials have intrinsic advantages, such as structural diversities, high NLO susceptibilities, and clear structure-property relationships. These "bottom-up" fabrication approaches are proposed to be combined with the "top-down" techniques such as lithography, etc., to generate multifunctionality by coupling light and matter on the (sub)wavelength scale.

  2. Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors

    SciTech Connect

    Sweany, M; Bernstein, A; Dazeley, S; Dunmore, J; Felde, J; Svoboda, R; Tripathi, S M

    2011-09-21

    Cherenkov detectors employ various methods to maximize light collection at the photomultiplier tubes (PMTs). These generally involve the use of highly reflective materials lining the interior of the detector, reflective materials around the PMTs, or wavelength-shifting sheets around the PMTs. Recently, the use of water-soluble wavelength-shifters has been explored to increase the measurable light yield of Cherenkov radiation in water. These wave-shifting chemicals are capable of absorbing light in the ultravoilet and re-emitting the light in a range detectable by PMTs. Using a 250 L water Cherenkov detector, we have characterized the increase in light yield from three compounds in water: 4-Methylumbelliferone, Carbostyril-124, and Amino-G Salt. We report the gain in PMT response at a concentration of 1 ppm as: 1.88 {+-} 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 {+-} 0.03 for Carbostyril-124, and 1.20 {+-} 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.

  3. Probing the parsec-scale accretion flow of 3C 84 with millimeter wavelength polarimetry

    SciTech Connect

    Plambeck, R. L.; Bower, G. C.; Rao, Ramprasad; Marrone, D. P.; Jorstad, S. G.; Marscher, A. P.; Doeleman, S. S.; Fish, V. L.; Johnson, M. D.

    2014-12-10

    We report the discovery of Faraday rotation toward radio source 3C 84, the active galactic nucleus in NGC 1275 at the core of the Perseus Cluster. The rotation measure (RM), determined from polarization observations at wavelengths of 1.3 and 0.9 mm, is (8.7 ± 2.3)× 10{sup 5} rad m{sup –2}, among the largest ever measured. The RM remained relatively constant over a 2 yr period even as the intrinsic polarization position angle wrapped through a span of 300°. The Faraday rotation is likely to originate either in the boundary layer of the radio jet from the nucleus or in the accretion flow onto the central black hole. The accretion flow probably is disk-like rather than spherical on scales of less than a parsec, otherwise the RM would be even larger.

  4. Computing Global Mosaics of Titan With the VIMS Imaging Spectrometer

    NASA Astrophysics Data System (ADS)

    Le Mouelic, S.; Cornet, T.; Rodriguez, S.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

    2015-12-01

    The Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini observes the surface of Titan in seven narrow atmospheric windows in the infrared at 0.93, 1.08, 1.27, 1.59, 2.01, 2.68-2.78, and 4.9-5.1 microns. We have produced a global hyperspectral mosaic of the complete VIMS data set of Titan between T0 (July 2004) and T112 flyby (July 2015), by merging all the data cubes sorted by increasing spatial resolution, with the high resolution images on top of the mosaic and the low resolution images used as background. We filtered out the observing geometry in order to remove the pixels acquired in too extreme illuminating and viewing conditions, which systematically produce atmospheric artifacts. We used thresholds of 80° both on the incidence and emission angles, 100° on the phase angle, and 7 on the airmass. These thresholds corresponds to a trade-off between surface coverage and data quality. The viewing geometry is normalized at first order using a surface photometric function derived from the observation at 5 μm, where the atmospheric scattering is almost negligible. We also use the wings of the atmospheric windows as a proxy to correct for the amount of additive scattering present in the center of these windows, where the surface is seen by VIMS. Various color composites can then be produced using combinations of different wavelengths to emphasize surface heterogeneities. Among these, a RGB composite with red controlled by the 5 μm image, the green by the 2 μm image and the blue by the 1.27 μm, reveals the extent of equatorial dune fields appearing in brownish tones. Bluish areas corresponds to regions possibly enriched in water ice or other organic compounds. Composite of band ratios such as 1.59/1.27 μm, 2.03/1.27 μm and 1.27/1.08 also prove to be more useful to better emphasize surface variations, even if they are also more sensitive to residual artefacts due to atmospheric and geometric effects or calibration residuals.

  5. Mimas: Preliminary Evidence For Amorphous Water Ice from VIMS

    NASA Technical Reports Server (NTRS)

    Cruikshank, Dale P.; Marzo, G. A.; Pinilla-Alonso, N.; Roush, T. L.; Mastrapa, R. M.; DalleOre, C. M.; Buratti, B. J.; Stephan, K.

    2010-01-01

    We have conducted a statistical clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn s satellite Mimas. Seven VIMS cubes were geometrically projected and re-sampled to a common spatial resolution. The clustering technique consists of a partitioning algorithm coupled to a criterion that prevents sub-optimal solutions and tests for the influence of random noise in the measurements. The clustering technique is agnostic about the meaning of the clusters, and scientific interpretation requires their a posteriori evaluation. The preliminary results yielded five clusters, demonstrating that spectral variability across Mimas surface is statistically significant. The ratios of the means calculated for each of the clusters show structure within the 1.6- micron water ice band, as well as the shape and the central wavelength of the strong ice band at 2 micron, that map spatially in patterns apparently related to the topography of Mimas, in particular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similarities with laboratory spectra of amorphous and crystalline H2O ice (3) that are suggestive of the presence of an amorphous ice component in certain regions of Mimas, notably on the central peak of Herschel, on the crater floor, and in faults surrounding the crater. This may represent a mixture of both ice phases, or perhaps a layer of amorphous ice on a base of crystalline ice. Another possible occurrence of amorphous ice appears southwest of Herschel, close to the south pole.

  6. Mimas: Preliminary Evidence For Amorphous Water Ice From VIMS

    NASA Astrophysics Data System (ADS)

    Cruikshank, Dale P.; Marzo, G. A.; Pinilla-Alonso, N.; Roush, T. L.; Mastrapa, R. M.; Dalle Ore, C. M.; Buratti, B. J.; Stephan, K.; VIMS Team

    2010-10-01

    We have conducted a statistical clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn's satellite Mimas. Seven VIMS cubes were geometrically projected and re-sampled to a common spatial resolution. The clustering technique consists of a partitioning algorithm coupled to a criterion that prevents sub-optimal solutions and tests for the influence of random noise in the measurements. The clustering technique is agnostic about the meaning of the clusters, and scientific interpretation requires their a posteriori evaluation. The preliminary results yielded five clusters, demonstrating that spectral variability across Mimas’ surface is statistically significant. The ratios of the means calculated for each of the clusters show structure within the 1.6-µm water ice band, as well as the shape and the central wavelength of the strong ice band at 2 µm that map spatially in patterns apparently related to the topography of Mimas, in particular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similarities with laboratory spectra of amorphous and crystalline H2O ice (3) that are suggestive of the presence of an amorphous ice component in certain regions of Mimas, notably on the central peak of Herschel, on the crater floor, and in faults surrounding the crater. This may represent a mixture of both ice phases, or perhaps a layer of amorphous ice on a base of crystalline ice. Another possible occurrence of amorphous ice appears southwest of Herschel, close to the south pole. 1. Marzo, G. A. et al. J. Geophys. Res. 111, E03002, 2006 2. Marzo, G. A. et al. J. Geophys. Res. 113, E12009, 2008 3. Mastrapa, R. M., et al. Astrophys. J. 701, 1347-1356, 2009

  7. Probing Saturn's tropospheric cloud with Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Barstow, J. K.; Irwin, P. G. J.; Fletcher, L. N.; Giles, R. S.; Merlet, C.

    2016-06-01

    In its decade of operation the Cassini mission has allowed us to look deep into Saturn's atmosphere and investigate the processes occurring below its enshrouding haze. We use Visual and Infrared Mapping Spectrometer (VIMS) 4.6-5.2 μm data from early in the mission to investigate the location and properties of Saturn's cloud structure between 0.6 and 5 bar. We average nightside spectra from 2006 over latitude circles and model the spectral limb darkening using the NEMESIS radiative transfer and retrieval tool. We present our best-fit deep cloud model for latitudes -40∘ < λ <50∘ , along with retrieved abundances for NH3, PH3 and AsH3. We find an increase in NH3 abundance at the equator, a cloud base at ˜2.3 bar and no evidence for cloud particles with strong absorption features in the 4.6-5.2 μm wavelength range, all of which are consistent with previous work. Non-scattering cloud models assuming a composition of either NH3 or NH4SH, with a scattering haze overlying, fit limb darkening curves and spectra at all latitudes well; the retrieved optical depth for the tropospheric haze is decreased in the northern (winter) hemisphere, implying that the haze has a photochemical origin. Our ability to test this hypothesis by examining spectra at different seasons is restricted by the varying geometry of VIMS observations over the life of the mission, and the appearance of the Saturn storm towards the end of 2010.

  8. Comparison of Cassini/VIMS and Huygens/DISR observations: Implications for Titan's geology and atmospheric haze

    NASA Astrophysics Data System (ADS)

    Sotin, Christophe; Karkoschka, Eric; Lawrence, Ken; LeMouelic, Stephane; Rodriguez, Sebastien; Solomonidou, Anezina; Barnes, Jason; Brown, Robert; Buratti, Bonnie; Kirk, Randy; Soderblom, Jason; Soderblom, Larry; Baines, Kevin; Clark, Roger; Nicholson, Phil

    2015-04-01

    The Huygens probe made in situ observations of Titan's atmosphere and surface in an area of Titan now known as a high equatorial plateau named Adiri surrounded by dune fields. These observations, made in January 2005, provide ground truth for remote sensing observations. This study focuses on the comparison between observations made by the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini spacecraft and the Descent Imager / Spectral Radiometer (DISR) on the Huygens probe. Two of the DISR instrument suite are relevant to the comparison with VIMS: the high resolution imager (HRI) and the Downward-Looking Infrared Spectrometer (DLIS) whose spectral range overlaps with the VIMS instrument between 0.9- and 1.6-μm. The comparison provides key information that can be applied to the VIMS data set which globally covers Titan's surface. The VIMS instrument can observe Titan's surface in 7 spectral atmospheric windows centred at 0.93, 1.08, 1.27, 1.59, 2.01, 2.7-2.8 and 5 microns [1]. Determining the spectral properties of the surface, and therefore the composition, requires the removal of the atmospheric contribution which includes absorption and scattering by atmospheric molecules and haze particles. Radiative transfer models have been using the DISR derived opacities to retrieve the surface albedo of Titan's surface. Light curves derived from VIMS solar occultation observations show that the atmospheric opacities above 80 km are in very good agreement with the DISR observations. However, the extrapolation of the DISR-derived opacities below 80 km at wavelengths above 1.6-μm predicts opacities much larger than those derived from the VIMS solar occultation observations. At 5-μm, the DISR extrapolation predicts a value of the optical depth three times larger than the value derived from the VIMS observations. The radiative transfer model used to retrieve the surface albedo [2] must be corrected accordingly. The VIMS instrument acquired one high resolution image of

  9. Near-infrared spectra of liquid/solid acetylene under Titan relevant conditions and implications for Cassini/VIMS detections

    NASA Astrophysics Data System (ADS)

    Singh, S.; Cornet, T.; Chevrier, V. F.; Combe, J.-Ph.; McCord, T. B.; Roe, L. A.; Le Mouélic, S.; Le Menn, E.; Wasiak, F. C.

    2016-05-01

    Acetylene is thought to be abundant on Titan according to most photochemical models. While detected in the atmosphere, its likely presence at the surface still lacks physical evidence. It is thought that solid acetylene could be a major component of Titan's lakes shorelines and dry lakebed, detected as the 5 μm-bright deposits with the Cassini/VIMS instrument. Acetylene could also be present under its liquid form as dissolved solids in Titan's methane-ethane lakes, as emphasized by thermodynamics studies. This paper is devoted to the near-infrared spectroscopy study of acetylene under solid and liquid phases between 1 and 2.2 μm, synthesized in a Titan simulation chamber that is able to reproduce extreme temperature conditions. From experiments, we observed a ∼10% albedo increase between liquid acetylene at 193-188 K and solid acetylene at 93 K. Using the NIR spectroscopy technique we successfully calculated the reflectivity ratio of solid/liquid acetylene as 1.13. The second difference we observed between liquid and solid acetylene is a shift in the major absorption band detected at 1.54 μm, the shift of ∼0.01 μm occurring toward higher wavelength. In order to assess the detectability of acetylene on Titan using the Cassini/VIMS instrument, we adapted our spectra to the VIMS spectral resolution. The spectral band at 1.55 μm and a negative slope at 2.0 μm falls in the Cassini/VIMS atmospheric windows over several VIMS infrared spectels, thus Cassini/VIMS should be able to detect acetylene.

  10. Titan's aerosol optical properties with VIMS observations at the limb

    NASA Astrophysics Data System (ADS)

    Rannou, Pascal; Seignovert, Benoit; Le Mouelic, Stephane; Sotin, Christophe

    2016-06-01

    The study of Titan properties with remote sensing relies on a good knowledge of the atmosphere properties. The in-situ observations made by Huygens combined with recent advances in the definition of methane properties enable to model and interpret observations with a very good accuracy. Thanks to these progresses, we can analyze in this work the observations made at the limb of Titan in order to retrieve information on the haze properties as its vertical profiles but also the spectral behaviour between 0.88 and 5.2 µm. To study the haze layer and more generally the source of opacities in the stratosphere, we use some observation made at the limb of Titan by the VIMS instrument onboard Cassini. We used a model in spherical geometry and in single scattering, and we accounted for the multiple scattering with a parallel plane model that evaluate the multiple scattering source function at the plane of the limb. Our scope is to retrieve informations about the vertical distribution of the haze, its spectral properties, but also to obtain details about the shape of the methane windows to desantangle the role of the methane and of the aerosols. We started our study at the latitude of 55°N, with a image taken in 2006 with a relatively high spatial resolution (for VIMS). Our preliminary results shows the spectral properties of the aerosols are the same whatever the altitude. This is a consequence of the large scale mixing. From limb profile between 0.9 and 5.2 µm, we can probe the haze layer from about 500 km (at 0.9 µm) to the ground (at 5.2 µm). We find that the vertical profile of the haze layer shows three distinct scale heights with transitions around 250 km and 350 km. We also clearly a transition around 70-90 km that may be due to the top of a condensation layer.

  11. The ‘Excess’ Emission from the Warm Surface Adjacent to Active Fissures on Enceladus from Combined VIMS and CIRS Spectra

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Howell, Robert R.

    2015-11-01

    The exciting discovery of thermal emission from the tiger stripe fissures at the S. pole of Enceladus is a major highlight of the Cassini mission. Both VIMS (Visible and Infrared Mapping Spectrometer) and CIRS (Composite InfraRed Spectrometer) detect the thermal ‘blackbody’ spectrum emitted from the warm fissure areas. The VIMS instrument is uniquely suited to measuring the hottest active locations because VIMS covers the 3 to 5 micron wavelength range where the rising edge of the Planck function for these T~200 K areas dominates the emission spectrum. At longer wavelengths, the spectrum is more complicated because contributions from small hot areas and larger cooler areas combine to form the broad emission spectrum that is detected by the CIRS instrument at wavelengths >6.7 microns. It is the combination of VIMS and CIRS spectra that paint a more complete portrait of the fissure heat transfer processes. Using spectra that span both the VIMS and CIRS wavelengths places a stronger constraint on the T distribution near the fissures than consideration of the spectra from either instrument alone.We show that when the best (= highest spatial resolution, 800 m/pixel and smaller) VIMS and CIRS spectra of the fissure thermal emission are considered together, there is a large (up to 400%) component of ‘excess’ emission spanning 7 to 17 microns that requires explanation. New analysis of ~2 km spatial resolution VIMS spectra of the Damascus hot spot on 8/13/2010 are similar to the highest resolution 4/14/2012 VIMS Baghdad spectra, confirming that differences in location or time between the best VIMS and CIRS spectra do not explain away the excess. The obvious interpretation is that there are processes that transfer heat from the fissure eruption to the surface within 400 m of the fissure center in addition to heat conduction through the fissure walls. Candidate heat transfer processes include fallback of large warm low velocity ice particles from the edges of the

  12. Terahertz polarization spectroscopy in the near-field zone of a sub-wavelength-scale metal slit.

    PubMed

    Han, Daehoon; Lee, Kanghee; Jo, Hanlae; Song, Yunheung; Kim, Minhyuk; Ahn, Jaewook

    2016-09-19

    Time-domain spectroscopy is used to probe the polarization dependence of the terahertz-frequency absorption of α-lactose molecules in the near-field vicinity of a sub-wavelength-scale metal slit. The experimental result finds that the 0.53-THz absorption of this material has an unexpected polarization dependence, strongly coupled to the slit orientation; in particular, the electric wave in parallel polarization exhibits even complete vanishing of the otherwise resonant strong absorption. The physics behind this phenomena may be explained based on the Bethe's sub-wavelength diffraction: the electric field that is measured in the far field, but diffracted from a sub-wavelength-scale metal aperture, originates from solely magnetic dipole radiation and not from the electric dipole radiation, thus showing no electrically-coupled material response. PMID:27661871

  13. Cassini/VIMS observations of the moon

    USGS Publications Warehouse

    Belluci, G.; Brown, R.H.; Formisano, V.; Baines, K.H.; Bibring, J.-P.; Buratti, B.J.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Mennella, V.; Miller, E.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.

    2002-01-01

    In this paper, we present preliminary scientific results obtained from the analysis of VIMS (Visible and Infrared Mapping Spectrometer) lunar images and spectra. These data were obtained during the Cassini Earth flyby in August 1999. Spectral ratios have been produced in order to derive lunar mineralogical maps. Some spectra observed at the north-east lunar limb, show few unusual absorption features located at 0.357, 0.430 and 0.452 ??m, the origin of which is presently unknown. ?? 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

  14. Characterization of the Titan's VIMS - units: Using Spectral Slopes

    NASA Astrophysics Data System (ADS)

    Brossier, Jérémy F.; Jaumann, Ralf; Stephan, Katrin; Le Mouélic, Stéphane; Brown, Robert H.

    2016-04-01

    Since the equatorial regions of Titan have been fully observed by the Visible and Infrared Mapping Spectrometer (VIMS) [1], the analysis of false-color composites enables distinguishing four main spectral units: the equatorial bright, brown, blue, and 5 μm-bright spectral units [2-4]. More precisely, the equatorial bright plateaus and inselbergs correspond to water-ice substrate coated by a layer of organic sediments. Moreover, the blue materials are more likely enriched in water-ice, which consist of icy particles exposition derived from the high standing plateaus and deposited into the lowlands after fluvial/pluvial processes [5] and/or impact cratering [6]. These blue materials are mainly located at the frontier of the large bright plateaus, and hence considered as transition zones to the brown areas corresponding to the radar dunes [7]. Whereas these brown dunes consist on atmospheric aerosols (i.e. tholins) [4] contaminated with particles of water-ice. Here we try to better characterize these spectral units, through VIMS observations at high resolution from TA (Oct. 2004) to T114 (Nov. 2015). Regions of interest show local transition zones between the equatorial bright areas, the blue materials, and the brown dunes, suggesting weathering and erosional processes (e.g. the Huygens landing site; areas at the east of Xanadu province; and Bohai Sinus at the south of Quivira plateau) [5,8], and impact cratering (e.g. Sinlap, Selk, Menrva, and Paxsi craters) [6,9]. Areas exposing large (i.e. Tui and Hotei Regiones) and small (e.g. Yalaing Terra, NW Belet, and NW Fensal) 5 μm-bright units - presumed evaporitic deposits - are also included in this study [9-11]. Subtle differences in the spectral behavior of these four units can be enhanced by using ratios of VIMS channels. At short wavelengths (i.e. below 2 μm), brown and blue materials seem to correspond to a granular mixture of organic sediments - similar to the atmospheric aerosols - and water-ice particles [7

  15. Power scaling of a wavelength-narrowed diode laser system for pumping alkali vapors

    NASA Astrophysics Data System (ADS)

    Hersman, F. W.; Distelbrink, J. H.; Ketel, J.; Wilson, J.; Watt, D. W.

    2016-03-01

    We report a method for locking the output wavelength and reducing the spectral linewidth of diode lasers by feeding back light to the emitters from a wavelength selective external optical cavity. Ten years ago our team developed a stepped-mirror that allowed a single external cavity to lock the wavelength of a stack of diode array bars by equalizing path lengths between each emitter and the grating. Here we report combining one such step-mirror external cavity with an array of power dividers, each sending a portion of this feedback power to a separate diode array bar stack.

  16. Postoperative management of Vim DBS for tremor.

    PubMed

    Dowsey-Limousin, Patricia

    2002-01-01

    Stimulation of the ventralis intermedius (Vim) is a treatment of severe tremor from various origins. The adjustment of electrical parameters is done when the lesion-like effects of the implant disappear. Each contact is assessed successively, by using a constant pulse width of 60 microsec and a frequency of 130 Hz or above and progressively increasing the voltage. At the same time, the tremor and possible side effects are monitored. The most frequent side effects are paresthesias, dysarthria, muscle contractions related to stimulation of the pyramidal tract, and cerebellar syndrome. Medications have to be adjusted slowly, and often, particularly in case of Parkinson's disease, it is difficult to decrease the dosage. It is important to teach the patient to switch the stimulator on or off and check that it is working. Patients need to be seen within the 3 months after implant, then occasionally according to the effect. In the long-term, some patients will develop some rebound of tremor when they switch off and/or some tolerance to the effect of the stimulator, which can be difficult to manage. In case of Parkinson's disease, motor fluctuations and dyskinesias, that does not respond to Vim stimulation, can occur. PMID:11948778

  17. Global mapping of the surface of Titan through the haze with VIMS onboard Cassini

    NASA Astrophysics Data System (ADS)

    Le Mouélic, Stéphane; Cornet, Thomas; Rodriguez, Sébastien; Sotin, Christophe; Barnes, Jason W.; Brown, Robert H.; Lasue, Jérémie; Baines, K. H.; Buratti, Bonnie; Clark, Roger Nelson; Nicholson, Philip D.

    2016-10-01

    The Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini observes the surface of Titan through the atmosphere in seven narrow spectral windows in the infrared at 0.93, 1.08, 1.27, 1.59, 2.01, 2.68-2.78, and 4.9-5.1 microns. We have produced a global hyperspectral mosaic at 32 pixels per degrees of the complete VIMS data set of Titan between T0 (July 2004) and T120 (June 2016) flybys. We merged all the data cubes sorted by increasing spatial resolution, with the high resolution images on top of the mosaic and the low resolution images used as background. One of the main challenge in producing global spectral composition maps is to remove the seams between individual frames taken throughout the entire mission. These seams are mainly due to the widely varying viewing angles between data acquired during the different Titan flybys. These angles induce significant surface photometric effects and a strongly varying atmospheric (absorption and scattering) contribution, the scattering of the atmosphere being all the more present than the wavelength is short. We have implemented a series of empirical corrections to homogenize the maps, by correcting at first order for photometric and atmospheric scattering effects. Recently, the VIMS' IR wavelength calibration has been observed to be drifting from a total of a few nm toward longer wavelengths, the drift being almost continuously present over the course of the mission. Whereas minor at first order, this drift has implications on the homogeneity of the maps when trying to fit images taken at the beginning of the mission with images taken near the end, in particular when using channels in the narrowest atmospheric spectral windows. A correction scheme has been implemented to account for this subtle effect.

  18. Multi-wavelength, Multi-scale Observations of Outflows in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Plunkett, Adele Laurie Dennis

    During the early stages of star formation, an embedded protostar accretes mass and simultaneously expels mass and angular momentum in the form of a bipolar outflow. In the common case of clustered star formation, outflows likely impact their surrounding environment and influence subsequent star formation. Numerical simulations have shown that outflows can sustain turbulence and maintain a cluster in quasi-equilibrium; alternatively, it was proposed that outflows may trigger rather than regulate or inhibit star formation. Observations of outflows and their impact on clusters are challenging because they must probe spatial scales over several orders of magnitude --- from the size of a core (a few hundred AU, or N ~ 10-3 pc) to a cluster (a few pc) --- and previous works generally focused on one scale or the other. This thesis incorporates high-resolution, high-sensitivity interferometry observations (with millimeter/sub-millimeter wavelengths) complemented by observations obtained using single dish telescopes in order to assess molecular outflow properties and their cumulative impact in two young protostellar clusters: Serpens South and NGC 1333. Based on these case studies, I develop an evolutionary scenario for clustered star formation spanning the ages of the two clusters, about 0.1 - 1 Myr. Within this scenario, outflows in both Serpens South and NGC 1333 provide sufficient energy to sustain turbulence early in the protocluster formation process. In neither cluster do outflows provide enough energy to counter the gravitational potential energy and disrupt the entire cluster. However, most of the mass in outflows in both clusters have velocities greater than the escape velocity, and therefore the relative importance of outflow-driven turbulence compared with gravitational potential likely changes with time as ambient gas escapes. We estimate that enough gas mass will escape via outflows in Serpens South so that it will come to resemble NGC 1333 in terms of its

  19. Power scaling and wavelength tuning of diode-pumped Nd:LSO laser at 1.35 μm

    NASA Astrophysics Data System (ADS)

    Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Cui, Shengwei; Wang, Yi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Xu, Jun

    2016-08-01

    We report a power scaled laser operation of diode-pumped Nd:LSO lasers at 1.35 μm. With single-end-pumping scheme, maximum output power reaches 0.77 W at 1358.99 nm in free-running mode. By inserting an etalon, wavelength tuning can be realized with tuning range of at least 6.5 nm from 1356.95 nm to 1363.39 nm. Simultaneous dual-wavelength laser at 1331.63 and 1357.43 nm can also be generated with total output power of 0.19 W, for the first time to our knowledge. Further power scaling to 1.03 W of the 1358.99 nm laser is finally achieved by recycling the remaining pump power, which represents the highest output power so far for 1.3 μm silicate lasers.

  20. Theoretical Study of Light Trapping in Nanostructured Thin Film Solar Cells Using Wavelength-Scale Silver Particles.

    PubMed

    Dabirian, Ali; Taghavinia, Nima

    2015-07-15

    We propose and theoretically evaluate a plasmonic light trapping solution for thin film photovoltaic devices that comprises a monolayer or a submonolayer of wavelength-scale silver particles. We systematically study the effect of silver particle size using full-wave electromagnetic simulations. We find that light trapping is significantly enhanced when wavelength-scale silver particles rather than the ones with subwavelength dimensions are used. We demonstrate that a densely packed monolayer of spherical 700 nm silver particles enhances integrated optical absorption under standard air mass 1.5 global (AM1.5G) in a 7 μm-thick N719-sensitized solar cell by 40% whereas enhancement is smaller than 2% when 100 nm ones are used. Superior performance of wavelength-scale silver particles is attributed to high-order whispering gallery modes that they support. These modes scatter the light over a wider angular range, hence increasing the density of both waveguide and resonance modes within the dye-sensitized layer. PMID:26135021

  1. Cassini/VIMS observation of an Io post-eclipse brightening event

    USGS Publications Warehouse

    Bellucci, G.; D'Aversa, E.; Formisano, V.; Cruikshank, D.; Nelson, R.M.; Clark, R.N.; Baines, K.H.; Matson, D.; Brown, R.H.; McCord, T.B.; Buratti, B.J.; Nicholson, P.D.

    2004-01-01

    During the Cassini-Jupiter flyby, VIMS observed Io at different phase angles, both in full sunlight and in eclipse. By using the sunlight measurements, we were able to produce phase curves in the visual through all the near infrared wavelengths covered by the VIMS instrument (0.85-5.1 ??m). The phase angle spanned from ???2?? to ???120??. The measurements, done just after Io emerged from Jupiter's shadow, show an increase of about 15% in Io's reflectance with respect to what would be predicted by the phase curve. This behavior is observed at wavelengths >1.2 ??m. Moreover, just after emergence from eclipse an increase of about 25% is observed in the depth of SO2 frost bands at 4.07 and 4.35 ??m. At 0.879

  2. VIMS Observations of Titan During the First Two Close Flybys by the Cassini-Huygens Mission

    NASA Technical Reports Server (NTRS)

    Rodriquez, S.; LeMouelic, S.; Sotin, C.; Buratti, B. J.; Brown, R. H.

    2005-01-01

    The joint NASA-ESA-ASI Cassini-Huygens mission reached the saturnian system on July 1st 2004. It started the observations of Saturn s environment including its atmosphere, rings, and satellites (Phoebe, Iapetus and Titan). Titan, one of the primary scientific interests of the mission, is veiled by an ubiquitous thick haze. Its surface cannot be seen in the visible but as the haze effects decrease with increasing wavelength, there is signal in the infrared atmospheric windows if no clouds are present. Onboard the Cassini spacecraft, the VIMS instrument (Visual and Infrared Mapping Spectrometer) is expected to pierce the veil of the hazy moon and successfully image its surface in the infrared wavelengths, taking hyperspectral images in the range 0.4 to 5.2 micron. On 26 October (TA) and 13 December 2004 (TB), the Cassini-Huygens mission flew over Titan at an altitude lower than 1200 km at closest approach. VIMS acquired several tens of image cubes with spatial resolution ranging from a few tens of kilometers down to 1.5 kilometer per pixel, demonstrating its capability for studying Titan s geology.

  3. Beam displacement as a function of temperature and turbulence length scale at two different laser radiation wavelengths.

    PubMed

    Isterling, William M; Dally, Bassam B; Alwahabi, Zeyad T; Dubovinsky, Miro; Wright, Daniel

    2012-01-01

    Narrow laser beams directed from aircraft may at times pass through the exhaust plume of the engines and potentially degrade some of the laser beam characteristics. This paper reports on controlled studies of laser beam deviation arising from propagation through turbulent hot gases, in a well-characterized laboratory burner, with conditions of relevance to aircraft engine exhaust plumes. The impact of the temperature, laser wavelength, and turbulence length scale on the beam deviation has been investigated. It was found that the laser beam displacement increases with the turbulent integral length scale. The effect of temperature on the laser beam angular deviation, σ, using two different laser wavelengths, namely 4.67 μm and 632.8 nm, was recorded. It was found that the beam deviation for both wavelengths may be semiempirically modeled using a single function of the form, σ=a(b+(1/T)(2))(-1), with two parameters only, a and b, where σ is in microradians and T is the temperature in °C.

  4. Sub-cm Particles in Saturn's Rings from VIMS, UVIS, and RSS occultations

    NASA Astrophysics Data System (ADS)

    Jerousek, Richard Gregory; Colwell, Josh E.; Hedman, Matthew M.; Marouf, Essam A.; Esposito, Larry W.; Nicholson, Philip D.; French, Richard G.

    2016-10-01

    Particles sizes in Saturn's rings roughly follow a truncated power law. One way to determine the governing parameters of the size distribution is through the analysis of differential optical depths (Zebker et al. 1983). Non-axisymmetric self-gravity wakes complicate this approach when optical depth measurements at different wavelengths are not made at same viewing geometry. Using occultations spanning a wide range of viewing angles and from multiple instruments onboard Cassini (the Ultraviolet Imaging Spectrograph (UVIS), the Visual and Infrared Mapping Spectrometer (VIMS), and the Radio Science Subsystem (RSS)), we forward-model the properties of the self-gravity wakes in Saturn's A and B rings while simultaneously constraining the parameters of the cm – sub-cm particle size distribution. In the absence of wakes, and in regions where particles smaller than ~ 8.86 mm are present, VIMS stellar occultations measure larger optical depths than UVIS stellar occultations due to the diffraction of 2.9 μm light out of the small (0.25 × 0.5 mrad) VIMS field of view compared with UVIS which measures shorter wavelength (0.15 μm) light over a much larger (6.4 × 6.0 mrad) field of view. This excess optical depth combined with RSS X-band (λ = 3.6 cm) optical depths provides a way to probe both the power law slope and the minimum particle size. In the A and B rings where self-gravity wakes are prevalent, we use the wake model of Colwell et al. (2006, 2007) with an additional free parameter representing the excess optical depth which would be measured through the gaps between opaque wakes, by VIMS compared to UVIS. In the B ring and inner A ring we find and absence of sub-cm particles and power law slopes of q ~ 2.8. In the trans-Encke region, where there are a multitude of satellite driven resonances, we find an increasing abundance of sub-cm particles as the outer edge of the A ring is approached. In the C Ring and the Cassini Division, where self-gravity wakes are absent

  5. Multi-wavelength Monitoring of Lensed Quasars: Deciphering Quasar Structure at Micro-arcseconds Scales

    NASA Astrophysics Data System (ADS)

    Mosquera, Ana; Morgan, Christopher W.; Kochanek, Christopher S.; Dai, Xinyu; Chen, Bin; MacLeod, Chelsea Louise; Chartas, George

    2016-01-01

    Microlensing in multiply imaged gravitationally lensed quasars provides us with a unique tool to zoom in on the structure of AGN and explore their physics in more detail. Microlensing magnification, caused primarily by stars and white dwarfs close to the line of sight towards the lensed quasar images, is seen as uncorrelated flux variations due to the relative motions of the quasar, the lens, its stars, and the observer, and it depends on the structural and dynamical properties of the source and the lens. Since the magnification depends upon the size of the source, we can use microlensing to measure the size of quasar emission regions. In essence, the amplitude of the microlensing variability encodes the source size, with smaller sources showing larger variability amplitudes. Using state of the art microlensing techniques, our team has performed pioneering research in the field based on multi-wavelength space and ground-based observations. Among the most remarkable results, using Chandra observations we have set the first quantitative constraints on the sizes of the X-ray emission regions of quasars. In this work l briefly describe the methodology, the results from our previous multi-wavelength monitoring programs, and the next frontier of exploring the dependence of the structure of the X-ray emission regions on black hole mass and X-ray energy.

  6. 1.3 mm WAVELENGTH VLBI OF SAGITTARIUS A*: DETECTION OF TIME-VARIABLE EMISSION ON EVENT HORIZON SCALES

    SciTech Connect

    Fish, Vincent L.; Doeleman, Sheperd S.; Beaudoin, Christopher; Bolin, David E.; Rogers, Alan E. E.; Blundell, Ray; Gurwell, Mark A.; Moran, James M.; Primiani, Rurik; Bower, Geoffrey C.; Plambeck, Richard; Chamberlin, Richard; Freund, Robert; Friberg, Per; Honma, Mareki; Oyama, Tomoaki; Inoue, Makoto; Krichbaum, Thomas P.; Lamb, James; Marrone, Daniel P.

    2011-02-01

    Sagittarius A*, the {approx}4 x 10{sup 6} M{sub sun} black hole candidate at the Galactic center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength very long baseline interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the Arizona Radio Observatory's Submillimeter Telescope on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat in California. Both Sgr A* and the quasar calibrator 1924-292 were observed over three consecutive nights, and both sources were clearly detected on all baselines. For the first time, we are able to extract 1.3 mm VLBI interferometer phase information on Sgr A* through measurement of closure phase on the triangle of baselines. On the third night of observing, the correlated flux density of Sgr A* on all VLBI baselines increased relative to the first two nights, providing strong evidence for time-variable change on scales of a few Schwarzschild radii. These results suggest that future VLBI observations with greater sensitivity and additional baselines will play a valuable role in determining the structure of emission near the event horizon of Sgr A*.

  7. Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials

    NASA Astrophysics Data System (ADS)

    Moughames, J.; Jradi, S.; Chan, T. M.; Akil, S.; Battie, Y.; Naciri, A. En; Herro, Z.; Guenneau, S.; Enoch, S.; Joly, L.; Cousin, J.; Bruyant, A.

    2016-10-01

    We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications.

  8. Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials

    PubMed Central

    Moughames, J.; Jradi, S.; Chan, T. M.; Akil, S.; Battie, Y.; Naciri, A. En; Herro, Z.; Guenneau, S.; Enoch, S.; Joly, L.; Cousin, J.; Bruyant, A.

    2016-01-01

    We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications. PMID:27698476

  9. Density Wave Signatures In VIMS Spectral Data

    NASA Astrophysics Data System (ADS)

    Nicholson, Philip D.; Hedman, M. M.; Cassini VIMS Team

    2012-10-01

    Spectral scans of Saturn's rings by the Cassini VIMS instrument have revealed both regional and local variations in the depths of the water ice bands at 1.5 and 2.0 microns, which have been interpreted in terms of variations in regolith grain size and the amount of non-icy "contaminants" (Filacchione et al. 2012; Hedman et al. 2012). Noteworthy among the local variations are distinctive patterns associated with the four strong density waves in the A ring. Within each wavetrain there is a peak in band strength relative to the surrounding material, while extending on both sides of the wave is a "halo" of reduced band strength. The typical width of these haloes is 400-500 km, about 2-3 times the visible extent of the density waves. The origin of these features is unknown, but may involve enhanced collisional erosion in the wave zones and transport of the smaller debris into nearby regions. A similar pattern of band depth variations is also seen at several locations in the more opaque B ring in association with the strong 3:2 ILRs of Janus, Pandora and Prometheus. The former shows a pattern just like its siblings in the A ring, while the latter two resonances show haloes, but without central peaks. In each case, the radial widths of the halo approaches 1000 km, but stellar occultation profiles show no detectable density wavetrain. We suggest that this spectral signature may be a useful diagnostic for the presence of strong density waves in regions where the rings are too opaque for occultations to reveal a typical wave profile. More speculatively, the displacement of the haloes' central radii from the calculated ILR locations of 600-700 km could imply a surface density in the central B ring in excess of 500 g/cm^2. This research was supported by the Cassini/Huygens project.

  10. Spectral challenges of individual wavelength-scale particles: strong phonons and their distorted lineshapes.

    PubMed

    Ravi, Aruna; Malone, Marvin A; Luthra, Antriksh; Lioi, David; Coe, James V

    2013-07-01

    Beyond our own interest in airborne particulate matter, the prediction of extinction and absorption spectra of single particles of mixed composition has wide use in astronomy, geology, atmospheric sciences, and nanotechnology. Single particle spectra present different challenges than traditional spectroscopic approaches. To quantify the amount of a material in a bulk sample (molecules in solution or the gas phase), one might employ the Beer-Lambert law assuming a simple slab-type assay geometry and averaging over orientation, whereas with single particles one might have a specific orientation and require a nonlinear, Mie-like particle theory. The complicating single particle issues include: strong and broad scattering at wavelengths similar to the particle size, phonon lineshape phase shifting, particle shape effects, distortion of transition lineshapes by strong vibrational bands, bi- and trirefringence, crystal orientation effects including dispersion, and composition mixtures. This work uses a combination of three-dimensional finite difference time domain (3D-FDTD) calculations and experimental infrared spectra on single, crystalline quartz particles to illustrate some of the challenges--in particular the distortion of lineshapes by strong phonons that lie within a range of strong scattering. It turns out that many mineral dust components in the inhalable size range have strong phonons. A Mie-Bruggeman model for single particle spectra is presented to isolate the effects of strong phonons on lineshapes which has utility for analysing the spectra of single, mixed-composition particles. This model will ultimately enable the determination of volume fractions of components in single particles that are mixtures of many materials with strong phonons, as are the dust particles breathed into people's lungs. PMID:23703537

  11. Spectral challenges of individual wavelength-scale particles: strong phonons and their distorted lineshapes.

    PubMed

    Ravi, Aruna; Malone, Marvin A; Luthra, Antriksh; Lioi, David; Coe, James V

    2013-07-01

    Beyond our own interest in airborne particulate matter, the prediction of extinction and absorption spectra of single particles of mixed composition has wide use in astronomy, geology, atmospheric sciences, and nanotechnology. Single particle spectra present different challenges than traditional spectroscopic approaches. To quantify the amount of a material in a bulk sample (molecules in solution or the gas phase), one might employ the Beer-Lambert law assuming a simple slab-type assay geometry and averaging over orientation, whereas with single particles one might have a specific orientation and require a nonlinear, Mie-like particle theory. The complicating single particle issues include: strong and broad scattering at wavelengths similar to the particle size, phonon lineshape phase shifting, particle shape effects, distortion of transition lineshapes by strong vibrational bands, bi- and trirefringence, crystal orientation effects including dispersion, and composition mixtures. This work uses a combination of three-dimensional finite difference time domain (3D-FDTD) calculations and experimental infrared spectra on single, crystalline quartz particles to illustrate some of the challenges--in particular the distortion of lineshapes by strong phonons that lie within a range of strong scattering. It turns out that many mineral dust components in the inhalable size range have strong phonons. A Mie-Bruggeman model for single particle spectra is presented to isolate the effects of strong phonons on lineshapes which has utility for analysing the spectra of single, mixed-composition particles. This model will ultimately enable the determination of volume fractions of components in single particles that are mixtures of many materials with strong phonons, as are the dust particles breathed into people's lungs.

  12. A large-scale cosmic microwave background anisotropy measurement at millimeter and submillimeter wavelengths

    NASA Technical Reports Server (NTRS)

    Page, Lyman A.; Cheng, Edward S.; Meyer, Stephan S.

    1990-01-01

    A balloon-borne experiment to measure the anisotropy of the cosmic microwave background radiation at angular scales of 4 deg or greater is reported. The instrument simultaneously measures in four spectral bands centered on 5.6, 8.7, 15.8, and 22.5/cm. Three results are presented: (1) the 95-percent confidence limit for monochromatic anisotropies is 0.0001 or less on angular scales of 10 deg; (2) the Galactic plane dust emission at l = 42 deg is consistent with a nu-squared emissivity law at frequencies above 15/cm, with excess emission below 15/cm; and (3) atmospheric ozone at an altitude of 35 km may form clumps as large as Delta emissivity/emissivity = 0.002.

  13. Mapping the Atmospheric and Surface Properties of Titan by the Massive Inversion of Cassini/VIMS Spectra

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Rodriguez, Sébastien; Appéré, Thomas; Vincendon, Mathieu; Douté, Sylvain; LeMouelic, Stéphane; Rannou, Pascal; Sotin, Christophe; Barnes, Jason W.; Coustenis, Athena; Brown, Robert H.

    2014-11-01

    Since the beginning of the Cassini mission, the imaging spectrometer VIMS has acquired ~40000 hyperspectral images of Titan containing several millions of spectra. Such a huge amount of data cannot be analyzed with a radiative transfer solver like SHDOM because of computational limits. Nevertheless, such a solver is the most suited tool to extract simultaneous information of the atmosphere and the surface of Titan from VIMS datacubes. We have developed a method of analyzing VIMS data that consents to use the power of a RT model without the inconvenience of long computational times, by the creation of look-up tables for different values of the RT model's parameters (geometry of the observation, surface albedo, aerosols opacity). We employ up-to-date information on gaseous spectral coefficients, aerosols’ optical properties and Titan’s climatology. These look-up tables, appropriately interpolated, are then used to minimize the observations and create simultaneous maps of aerosols opacity and of surface albedo (at the wavelengths of Titan’s spectral windows). This method lowers the computational time by a factor of several thousands and thus, for the first time, a truly massive treatment of VIMS data. In this paper we present the results of our method applied to the area of the Huygens landing site and their comparison with the results of other Cassini instruments. We also show the retrieved maps of a region observed multiple times at different Cassini flybys with different observational conditions, as the T13/T17 mosaic of the Atzlan area. The perspectives for atmospheric and surface seasonal monitoring are highlighted.

  14. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  15. Non-O1/Non-O139 Vibrio cholerae Avian Isolate from France Cocarrying the bla(VIM-1) and bla(VIM-4) Genes.

    PubMed

    Aberkane, Salim; Compain, Fabrice; Barraud, Olivier; Ouédraogo, Abdoul-Salam; Bouzinbi, Nicolas; Vittecoq, Marion; Jean-Pierre, Hélène; Decré, Dominique; Godreuil, Sylvain

    2015-10-01

    We describe here a non-O1/non-O139 Vibrio cholerae isolate producing both VIM-1 and VIM-4 carbapenemases. It was isolated from a yellow-legged gull in southern France. The blaVIM genes were part of a class 1 integron structure located in an IncA/C plasmid. This study emphasizes the presence of carbapenemase genes in wildlife microbiota.

  16. Non-O1/Non-O139 Vibrio cholerae Avian Isolate from France Cocarrying the bla(VIM-1) and bla(VIM-4) Genes.

    PubMed

    Aberkane, Salim; Compain, Fabrice; Barraud, Olivier; Ouédraogo, Abdoul-Salam; Bouzinbi, Nicolas; Vittecoq, Marion; Jean-Pierre, Hélène; Decré, Dominique; Godreuil, Sylvain

    2015-10-01

    We describe here a non-O1/non-O139 Vibrio cholerae isolate producing both VIM-1 and VIM-4 carbapenemases. It was isolated from a yellow-legged gull in southern France. The blaVIM genes were part of a class 1 integron structure located in an IncA/C plasmid. This study emphasizes the presence of carbapenemase genes in wildlife microbiota. PMID:26169421

  17. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Rodriguez, Sebastien; Maltagliati, Luca; Sotin, Christophe; Rannou, Pascal; Bézard, Bruno; Cornet, Thomas

    2016-10-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008).Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 μm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°.We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  18. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Rodriguez, Sebastien; Sotin, Christophe; Rannou, Pascal; Bezard, Bruno; Cornet, Thomas

    2016-06-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008). Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 µm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°. We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  19. Novel VIM Metallo-β-Lactamase Variant from Clinical Isolates of Enterobacteriaceae from Algeria ▿

    PubMed Central

    Robin, Frédéric; Aggoune-Khinache, Nadjet; Delmas, Julien; Naim, Malek; Bonnet, Richard

    2010-01-01

    Five different strains of bacteria belonging to the family Enterobacteriaceae were isolated from two patients hospitalized in the intensive care unit of the Central Military Hospital of Algiers, Algeria. All five strains, one Providencia stuartii strain, two Escherichia coli strains, and two Klebsiella pneumoniae strains, were intermediate or resistant to all β-lactams, including carbapenems. Synergy between imipenem and EDTA was observed for all five strains. The results of the PCR experiment confirmed the presence of a blaVIM gene in all five strains. The blaVIM genes were located as part of a class 1 integron on a 180-kb conjugative plasmid. They encoded a novel metallo-β-lactamase designated VIM-19, which differed from the parental enzyme VIM-1 by only two substitutions: Ser228Arg, previously observed in the closely related enzyme VIM-4, and Asn215Lys, not previously observed in other VIM-type carbapenemases. VIM-19 was further characterized after purification through determination of its kinetic constants. This enzyme was inhibited by EDTA and hydrolyzed penicillins, cephalosporins, and carbapenems, as observed for other VIM-type carbapenemases but with greater catalytic efficiency against penicillins than VIM-1. VIM-19 is the first carbapenemase enzyme identified from an isolate from Algeria. These results confirm the emergence of VIM-4-like enzymes in members of the family Enterobacteriaceae from Mediterranean countries. PMID:19901092

  20. Temporal variations of Titan's surface with Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, A.; Hirtzig, M.; Rodriguez, S.; Stephan, K.; Lopes, R. M. C.; Drossart, P.; Sotin, C.; Le Mouélic, S.; Lawrence, K.; Bratsolis, E.; Jaumann, R.; Brown, R. H.

    2016-05-01

    We analyze Cassini VIMS data of several areas on Titan's surface looking for variations with time. Three of these locations are near the equator (10-30°S), namely Hotei Regio, Tui Regio and Sotra Patera; in some cases changes in brightness and/or in appearance were reported therein. We also investigate a portion of the undifferentiated plains, areas relatively homogeneous and dark in radar observations, located near 20-25°N. This is a follow-up on a previous paper in which we had inferred surface albedos for some distinct regions of interest (RoIs) identified within the Hotei, Tui and Sotra areas through a Principal Component Analysis (PCA) and radiative transfer (RT) modeling (Solomonidou [2014]. J. Geophys. Res. 119, 1729-1747). We apply the same methods here to a larger dataset looking for variations of the surface albedo with time and using the Huygens landing site as the 'ground truth' for calibration purposes. As expected, the undifferentiated plains remain unchanged from January 2010 to June 2012. Our analysis of Hotei Regio data from March 2005 to March 2009 also does not show any significant surface albedo variations within uncertainties. We note however that our RT retrievals are not optimal in this case because of the use of a plane-parallel code and the unfavorable geometry of the associated datasets. Conversely, Tui Regio and Sotra Patera show surface albedo fluctuations with time with pronounced trends for darkening and for brightening respectively. The Tui Regio spectrum exhibits a surface albedo decrease from March 2005 to February 2009, at 0.94, 1.08, 2.03, and 5 μm wavelengths, while the spectrum shape remains the same over that time. On the contrary, the Sotra Patera area became at least two times brighter within a year (April 2005-February 2006), at 1.58 μm, 2.03 μm, and 5 μm. We also retrieved surface albedo spectra for three reference regions surrounding Hotei, Tui and Sotra and for three additional regions we use as 'test cases' that

  1. Tracking and Reporting Data Using VIMS and VAMS. Module.

    ERIC Educational Resources Information Center

    Downs, W. A.

    This module on tracking and reporting data is 1 in a series of 10 modules written for vocational education teacher education programs. It is designed to provide a basic understanding of Missouri's Vocational Instructional Management System (VIMS) and Vocational Administrative Management System (VAMS). Introductory materials include the following:…

  2. Empirical Approaches To Reduce The Atmospheric Component In VIMS Surface Images Of Titan

    NASA Astrophysics Data System (ADS)

    Le Mouélic, S.; Cornet, T.; Rodriguez, S.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

    2010-12-01

    The Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini can see the surface of Titan in seven narrow atmospheric windows in the infrared at 0.93, 1.08, 1.27, 1.59, 2.01, 2.68-2.78, and 4.9-5.1 microns. In addition to the strong absorption by atmospheric gases (mainly methane and nitrogen), the presence of aerosols in the atmosphere blurs the images at short wavelengths due to a very strong scattering effect, which acts as an additive component to the signal coming from the surface. We have produced a global hyperspectral mosaic of the complete VIMS archive between T0 (July 2004) and T66 flyby (January 2010), by merging all the data cubes sorted by increasing spatial resolution in order to put the high resolution images on top and to use the low resolution images as background. We filtered out the observing geometry in order to remove the pixels acquired in too extreme illuminating and viewing conditions, which systematically amplify the atmospheric artifacts. We used thresholds of 80° both on the incidence and emission angles, and 100° on the phase angle. We first focused our study on the 5 microns window, where the additive component from the haze scattering is negligible, in order to investigate the multiplicative factor which should be used to normalize the viewing geometry between all flybys, and thus to reconcile observations acquired in very different viewing conditions. Indeed, if we exclude transient phenomena (mainly clouds and possible surface changes), the seams between all individual images should disappear after correction. We then investigated other windows at shorter wavelengths, where the additive scattering component cannot be neglected. We found that the wings of the atmospheric windows can be used as a proxy for the amount of additive scattering present in the center of these windows, where the surface is best seen by VIMS. In the band wings, the solar flux never reaches the ground. The corresponding signal therefore gives the

  3. Temperature maps of Saturn's satellites retrieved from Cassini-VIMS observations (Invited)

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, Fabrizio; Ciarniello, Mauro; Tosi, Federico; D'Aversa, Emiliano; Clark, Roger N.; Brown, Robert N.; Buratti, Bonnie J.; Cruikshank, Dale P.; Dalle Ore, Cristina M.; Scipioni, Francesca; Cerroni, Priscilla

    2014-11-01

    The spectral position of the 3.6 µm continuum peak measured on Cassini-VIMS reflectance spectra is used to infer the temperature of the regolith particles covering the surfaces of Saturn’s icy satellites. Laboratory measurements by Clark et al. (2012) have shown that 3.6 µm peak for pure crystalline water ice particles shifts towards shorter wavelengths when the sample is cooled, moving from about 3.65 µm at T=123 K to about 3.55 µm at T=88 K. A similar trend is observed also in the imaginary part (k) of the refractive index of water ice when the sample is cooled from T=140 K to 20 K (Mastrapa et al., 2009). Since water ice is the dominant endmember on Saturn’s satellites surfaces (Clark and Owensby, 1981; Clark et al., 1984; Filacchione et al., 2012), the measurement of the wavelength at which the 3.6 µm reflectance peak occurs can be considered as a temperature indicator. We report on our temperature maps of Mimas, Enceladus, Tethys, Dione and Rhea derived by applying this method to Cassini-VIMS data taken at spatial resolution of 20-40 km/pixel. These maps allow us to correlate the temperature distribution with solar illumination conditions and with geological features. On average Enceladus’ mid-latitudes regions appear at T<100 K while the south pole tiger-stripes active area shows a thermal emission at T>115 K. Tethys’ and Mimas’ equatorial lenses show significant thermal anomalies: despite the fact that these features have low visible albedo they appear colder than the surrounding mid-latitude regions as a consequence of a much higher thermal inertia. On Mimas, the floor of Herschel crater appears warmer (T>115 K) than the adjacent equatorial lens area (T<110 K). Finally, the analysis of Dione shows that the temperature across the bright wispy terrains is lower than the nearby low albedo areas.

  4. Characterizing the Effects of Washing by Different Detergents on the Wavelength-Scale Microstructures of Silk Samples Using Mueller Matrix Polarimetry.

    PubMed

    Dong, Yang; He, Honghui; He, Chao; Zhou, Jialing; Zeng, Nan; Ma, Hui

    2016-01-01

    Silk fibers suffer from microstructural changes due to various external environmental conditions including daily washings. In this paper, we take the backscattering Mueller matrix images of silk samples for non-destructive and real-time quantitative characterization of the wavelength-scale microstructure and examination of the effects of washing by different detergents. The 2D images of the 16 Mueller matrix elements are reduced to the frequency distribution histograms (FDHs) whose central moments reveal the dominant structural features of the silk fibers. A group of new parameters are also proposed to characterize the wavelength-scale microstructural changes of the silk samples during the washing processes. Monte Carlo (MC) simulations are carried out to better understand how the Mueller matrix parameters are related to the wavelength-scale microstructure of silk fibers. The good agreement between experiments and simulations indicates that the Mueller matrix polarimetry and FDH based parameters can be used to quantitatively detect the wavelength-scale microstructural features of silk fibers. Mueller matrix polarimetry may be used as a powerful tool for non-destructive and in situ characterization of the wavelength-scale microstructures of silk based materials. PMID:27517919

  5. Characterizing the Effects of Washing by Different Detergents on the Wavelength-Scale Microstructures of Silk Samples Using Mueller Matrix Polarimetry

    PubMed Central

    Dong, Yang; He, Honghui; He, Chao; Zhou, Jialing; Zeng, Nan; Ma, Hui

    2016-01-01

    Silk fibers suffer from microstructural changes due to various external environmental conditions including daily washings. In this paper, we take the backscattering Mueller matrix images of silk samples for non-destructive and real-time quantitative characterization of the wavelength-scale microstructure and examination of the effects of washing by different detergents. The 2D images of the 16 Mueller matrix elements are reduced to the frequency distribution histograms (FDHs) whose central moments reveal the dominant structural features of the silk fibers. A group of new parameters are also proposed to characterize the wavelength-scale microstructural changes of the silk samples during the washing processes. Monte Carlo (MC) simulations are carried out to better understand how the Mueller matrix parameters are related to the wavelength-scale microstructure of silk fibers. The good agreement between experiments and simulations indicates that the Mueller matrix polarimetry and FDH based parameters can be used to quantitatively detect the wavelength-scale microstructural features of silk fibers. Mueller matrix polarimetry may be used as a powerful tool for non-destructive and in situ characterization of the wavelength-scale microstructures of silk based materials. PMID:27517919

  6. A measurement of the large-scale cosmic microwave background anisotropy at 1.8 millimeter wavelength

    NASA Technical Reports Server (NTRS)

    Meyer, Stephan S.; Cheng, Edward S.; Page, Lyman A.

    1991-01-01

    This measurement of the large-scale cosmic microwave background radiation (CMBR) anisotropy places the most stringent constraints to date on fluctuations in the CMBR on angular scales greater than about 4 deg. Using a four-channel bolometric radiometer operating at 1.8, 1.1, 0.63, and 0.44 mm, the diffuse sky brightness over half of the northern hemisphere has been mapped with an angular resolution of 3.8 deg. Analysis of the sky map at the longest wavelength for Galactic latitudes of 15 deg or more yields a 95-percent confidence level upper limit on fluctuations of the CMBR at Delta T/T of 1.6 x 10 to the -5th with a statistical power of 92 percent for Gaussian fluctuations at a correlation angle of 13 deg. Between 3 deg and 22 deg, the upper limit of fluctuations is 4.0 x 10 to the -5th . An anisotropy is detected in the map, but it cannot yet be attributed to primordial sources. The ultimate sensitivity for this experiment is 7 x 10 to the -6th over this angular range for Gaussian fluctuations.

  7. Correlations between VIMS and RADAR data over the surface of Titan: Implications for Titan's surface properties

    NASA Astrophysics Data System (ADS)

    Tosi, F.; Orosei, R.; Seu, R.; Coradini, A.; Lunine, J. I.; Filacchione, G.; Capaccioni, F.; Cerroni, P.; Brown, R. H.; Cassini Vims; Radar Teams

    2010-04-01

    We present new results combining the VIMS and RADAR data on Titan's surface. In RADAR data we consider two geophysical quantities: the normalized backscatter cross-section obtained from the scatterometer measurement, corrected for the incidence angle, and the calibrated antenna temperature determined from the radiometer measurement, as found in publicly available data products. In VIMS data, combining spatial and spectral information, we have selected some atmospheric windows in the spectral range between 2 and 5 μm, providing the best optical depth to measure surface reflectance. The two RADAR parameters are combined with VIMS data, with estimated errors, to produce an aggregate data set, that we process using multivariate classification methods to identify homogeneous taxonomic units in the multivariate space of the samples. The use of data sets from different instruments onboard the Cassini spacecraft has the potential to deepen our understanding of the nature of the surface. Our analysis relies on the G-mode method, which has been successfully used in the past for the classification of such diverse data sets as lunar rock samples, asteroids and planetary surfaces. Due to the large number of data of Titan, the classification work proceeds in several steps. In a previous work (Tosi et al., 2010), we analyzed the data acquired in Titan flybys: T3, T4, T8, T13 and T16, covering mostly the major bright and dark features seen around the equator, combined with VIMS infrared data, in order to validate the classification method. Now we focus on flybys: T23, T25, T28, T30, and T43, covering also regions of Titan located at higher latitudes, and partly including the polar regions. The obtained results are generally in agreement with previous work devoted both to the analysis of the scatterometry data through physical models and to the correlation between SAR and radiometry data at a high resolution scale. This evidence, evaluated for the first time through a multivariate

  8. Correlations between VIMS and RADAR data over the surface of Titan: Implications for Titan's surface properties

    NASA Astrophysics Data System (ADS)

    Tosi, F.; Orosei, R.; Seu, R.; Coradini, A.; Lunine, J. I.; Filacchione, G.; Capaccioni, F.; Cerroni, P.; Flamini, E.; Brown, R. H.; Cruikshank, D. P.; Lopes, R. M.

    2010-12-01

    We present new results combining the VIMS and RADAR medium resolution data on Titan’s surface. In RADAR data we consider two geophysical quantities: the normalized backscatter cross-section obtained from the scatterometer measurement, corrected for the incidence angle, and the calibrated antenna temperature determined from the radiometer measurement, as found in publicly available data products. In VIMS data, combining spatial and spectral information, we have selected some atmospheric windows in the spectral range between 2 and 5 μm, providing the best optical depth to measure surface reflectance. The two RADAR parameters are combined with VIMS data, with estimated errors, to produce an aggregate data set, that we process using multivariate classification methods to identify homogeneous taxonomic units in the multivariate space of the samples. Such units in fact reveal compositional trends in the surface, that are likely related to different abundances of simple ices and/or hydrocarbons. Our analysis relies on the G-mode method, which has been successfully used in the past for the classification of such diverse data sets as lunar rock samples, asteroids and planetary surfaces. Due to the large number of data of Titan, the classification work proceeds in several steps. In a previous work (Tosi et al., 2010), we analyzed the data acquired in Titan flybys: T3, T4, T8, T13 and T16, covering mostly the major bright and dark features seen around the equator, combined with VIMS infrared data, in order to validate the classification method. Now we focus on flybys: T23, T25, T28, T30, and T43, covering also regions of Titan located at higher latitudes, and partly including the polar regions. The obtained results are generally in agreement with previous work devoted both to the analysis of the scatterometry data through physical models and to the correlation between SAR and radiometry data at a high resolution scale. This classification can be expanded and refined as new

  9. Correlations between VIMS and RADAR data over the surface of Titan: Implications for Titan's surface properties.

    NASA Astrophysics Data System (ADS)

    Tosi, Federico; Orosei, Roberto; Seu, Roberto; Coradini, Angioletta; Lunine, Jonathan; Filacchione, Gianrico; Capaccioni, Fabrizio; Cerroni, Priscilla; Brown, Robert

    2010-05-01

    We present new results combining the VIMS and RADAR data on Titan's surface. In RADAR data we consider two geophysical quantities: the normalized backscatter cross-section obtained from the scatterometer measurement, corrected for the incidence angle, and the calibrated antenna temperature determined from the radiometer measurement, as found in publicly available data products. In VIMS data, combining spatial and spectral information, we have selected some atmospheric windows in the spectral range between 2 and 5 μm, providing the best optical depth to measure surface reflectance. The two RADAR parameters are combined with VIMS data, with estimated errors, to produce an aggregate data set, that we process using multivariate classification methods to identify homogeneous taxonomic units in the multivariate space of the samples. The use of data sets from different instruments onboard the Cassini spacecraft has the potential to deepen our understanding of the nature of the surface. Our analysis relies on the G-mode method, which has been successfully used in the past for the classification of such diverse data sets as lunar rock samples, asteroids and planetary surfaces. Due to the large number of data of Titan, the classification work proceeds in several steps. In a previous work (Tosi et al., 2010), we analyzed the data acquired in Titan flybys: T3, T4, T8, T13 and T16, covering mostly the major bright and dark features seen around the equator, combined with VIMS infrared data, in order to validate the classification method. Now we focus on flybys: T23, T25, T28, T30, and T43, covering also regions of Titan located at higher latitudes, and partly including the polar regions. The obtained results are generally in agreement with previous work devoted both to the analysis of the scatterometry data through physical models and to the correlation between SAR and radiometry data at a high resolution scale. This evidence, evaluated for the first time through a multivariate

  10. Clouds and hazes vertical structure of a Saturn's giant vortex from Cassini/VIMS-V data analysis

    NASA Astrophysics Data System (ADS)

    Oliva, F.; Adriani, A.; Moriconi, M. L.; Liberti, G. L.; D'Aversa, E.; Filacchione, G.

    2016-11-01

    We studied the evolution of a giant tropospheric vortex formed in the wake of the storm that encircled Saturn from December 2010 to July 2011 (Fletcher et al. [2011a] Science, 332, 1413-1417; Fletcher et al. [2012] Icarus, 221, 560-586; Sánchez-Lavega et al. [2011] Nature, 475, 71-74; Sánchez-Lavega et al. [2012] Icarus, 220, 561-576; Sayanagi et al. [2013] Icarus, 223, 460-478; Fischer et al. [2011] Nature, 475, 75-77) taking advantage of the observations acquired by the instruments on board the Cassini spacecraft. In particular, the Visual and Infrared Mapping Spectrometer (VIMS) imaged the vortex several times. In this work we analyzed two observations registered by the visual channel of VIMS (VIMS-V) on 08/24/2011 and 01/04/2012, both after the active phase of the storm, and characterized quantitatively the vertical structure of the clouds and hazes above the vortex. Until now, VIMS-V dataset has been scarcely exploited to perform such an analysis. The IR channel of VIMS has always been preferred since it covers wavelengths containing spectral information on a wider range of altitudes in the atmosphere. Nevertheless, in our analysis we investigate the information content of VIMS-V observations and demonstrate that the covered spectral range contains valuable information that are helpful to improve our knowledge on the properties of Saturn's upper atmosphere. We developed a forward radiative transfer model to describe Saturn's atmosphere and simulate VIMS-V spectra in the 0.35-1.05 μm wavelength range. The analysis has then been performed by means of an inverse model that we built on the basis of the Bayesian approach. Spatial distributions of effective radii, column number densities and top pressures of the cloud decks have been mapped and as a by-product of our analysis we also suggest a modified spectral shape for the imaginary part of the refractive index of the tropospheric haze, with respect to the shape described in the study of Karkoschka and Tomasko

  11. Micro- and nano-scale optical devices for high density photonic integrated circuits at near-infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Chatterjee, Rohit

    In this research work, we explore fundamental silicon-based active and passive photonic devices that can be integrated together to form functional photonic integrated circuits. The devices which include power splitters, switches and lenses are studied starting from their physics, their design and fabrication techniques and finally from an experimental standpoint. The experimental results reveal high performance devices that are compatible with standard CMOS fabrication processes and can be easily integrated with other devices for near infrared telecom applications. In Chapter 2, a novel method for optical switching using nanomechanical proximity perturbation technique is described and demonstrated. The method which is experimentally demonstrated employs relatively low powers, small chip footprint and is compatible with standard CMOS fabrication processes. Further, in Chapter 3, this method is applied to develop a hitless bypass switch aimed at solving an important issue in current wavelength division multiplexing systems namely hitless switching of reconfigurable optical add drop multiplexers. Experimental results are presented to demonstrate the application of the nanomechanical proximity perturbation technique to practical situations. In Chapter 4, a fundamental photonic component namely the power splitter is described. Power splitters are important components for any photonic integrated circuits because they help split the power from a single light source to multiple devices on the same chip so that different operations can be performed simultaneously. The power splitters demonstrated in this chapter are based on multimode interference principles resulting in highly compact low loss and highly uniform power splitting to split the power of the light from a single channel to two and four channels. These devices can further be scaled to achieve higher order splitting such as 1x16 and 1x32 power splits. Finally in Chapter 5 we overcome challenges in device

  12. Cassini VIMS Preliminary Exploration of Titan's Surface Hemispheric Albedo Dichotomy

    NASA Technical Reports Server (NTRS)

    Nelson, R. M.; Brown, R. H.; Hapke, B. W.; Smythe, W. D.; Kamp, L.; Boryta, M.; Baines, K. H.; Bellucci, G.; Bibring, J.-P.; Buratti, B. J.

    2005-01-01

    We present preliminary evidence that suggests a hemispheric albedo dichotomy on Titan, the largest planetary satellite in the Solar System. We have also studied the photometric properties of several dark circular features on Titan's surface to test if they might be of impact origin. The evidence is derived from photometric analysis of selected surface regions taken at different Titanian longitudes and solar phase angles using images from the Cassini Saturn Orbiter Visual and Infrared Mapping Spectrometer (VIMS). The VIMS instrument is able to image Titan's surface at spectral windows (e.g. 2.02 microns) in its atmosphere where methane, the principal atmospheric absorber is transparent. Additional information is included in the original extended abstract.

  13. Saturn B and C ring studies at multiple wavelengths

    NASA Astrophysics Data System (ADS)

    Spilker, Linda; Deau, Estelle; Morishima, Ryuji; Filacchione, Gianrico; Hedman, Matt; Nicholson, Phil; Colwell, Josh; Bradley, Todd; Pilorz, Stu

    2015-04-01

    We can learn a great deal about the characteristics of Saturn's ring particles and their regoliths by modeling the changes in their brightness, color and temperature with changing viewing geometry over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly studied using data from the lit and unlit main rings at multiple geometries and solar elevations. Using multi-wavelength data sets allow us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation. With the high spatial resolution of the Cassini data it is now possible to analyze these effects at smaller spatial scales and characterize higher optical depth regions in faint rings such as the outer C ring, where albedo differences may be present. The CIRS temperature and ISS color variations are confined primarily to phase angle over a range of solar elevations with only small differences from changing spacecraft elevation. Color and temperature dependence with varying solar elevation angle are also observed. Brightness dependence with changing solar elevation angle and phase angle is observed with UVIS. VIMS observations show that the IR ice absorption band depths are a very weak function of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces of the clumps, as

  14. Compositional mapping of Titan's North Pole with VIMS

    NASA Astrophysics Data System (ADS)

    MacKenzie, Shannon; Barnes, Jason W.; Sotin, Christophe; Soderblom, Jason M.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Baines, Kevin; Buratti, Bonnie J.; Clark, Roger Nelson

    2016-10-01

    Titan's methane lakes and seas are almost exclusively found at the moon's north polar region. The factors that drive this distribution are not yet well understood. The poles are generally lower in elevation and a few Kelvin colder than the equator. But the south pole looks very different from the north with only one large lake and a few smaller bodies. To further illuminate what processes might make the north pole unique, we investigate the region's compositional variability and the connection to morphology by analyzing the entirety of the publically available data from Cassini's Visual and Infrared Mapping Spectrometer (VIMS) that cover the north pole. Because VIMS can only observe the surface in seven IR windows, we identify the relative composition ("spectral units") of the north polar terrain (90N - 45N) and compare our results to those of Birch et al. (Icarus, in revision), who defined geomorphological units in Cassini RADAR north polar data. We find interesting correlations and examples of distinct composition boundaries in VIMS that aren't reflected in the RADAR data. These results provide a more complete context for lake formation/retention hypotheses as well as identify features for further study.

  15. Simultaneous Mapping of Titan's Atmospheric and Surface Properties Through the Massive Inversion of Cassini/VIMS Data

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Maltagliati, L.; Appéré, T.; Vincendon, M.; Douté, S.; Le Mouelic, S.; Rannou, P.; Sotin, C.; Barnes, J. W.; Coustenis, A.; Brown, R. H.

    2014-12-01

    A radiative transfer solver (i.e. SHDOM) is the most powerful tool to extract simultaneous information of the atmosphere and the surface of Titan from the hyperspectral data of the VIMS imaging spectrometer onboard Cassini. However, the sheer amount of data (~40000 VIMS cubes containing several millions of spectra since the beginning of the mission) makes this approach too demanding in computational time. In our analysis we use a radiative transfer model to create look-up tables for different values of the model's parameters (geometry of the observation, surface albedo, aerosols opacity). We employ up-to-date information on gaseous spectral coefficients, aerosols' optical properties and Titan's climatology. These look-up tables, appropriately interpolated, are then used to minimize the observations and create simultaneous maps of surface albedo at the wavelengths of Titan's spectral windows and of aerosols opacity. This approach allows the gain of a factor of several thousands in computational time and thus, for the first time, a truly massive treatment of VIMS data. This capacity of processing full mapping quickly will consent to monitor closely the global and local seasonal evolution of the atmosphere and the surface. We will present the results of our method applied to some cases of interest. We will analyze several hyperspectral images of the Huygens landing site and show the comparison of our results with observations of other Cassini instruments. We will also investigate regions that have been observed multiple times at different Cassini flybys with different observational conditions, as the T13/T17 mosaic of the Atzlan area. The perspectives for atmospheric and surface seasonal monitoring will be highlighted.

  16. The Saturnian satellite Rhea as seen by Cassini VIMS

    USGS Publications Warehouse

    Stephan, K.; Jaumann, R.; Wagner, R.; Clark, R.N.; Cruikshank, D.P.; Giese, B.; Hibbitts, C.A.; Roatsch, T.; Matz, K.-D.; Brown, R.H.; Filacchione, G.; Cappacioni, F.; Scholten, F.; Buratti, B.J.; Hansen, G.B.; Nicholson, P.D.; Baines, K.H.; Nelson, R.M.; Matson, D.L.

    2012-01-01

    Since the arrival of the Cassini spacecraft at Saturn in June 2004, the Visual and Infrared Mapping Spectrometer has obtained new spectral data of the icy satellites of Saturn in the spectral range from 0.35 to 5.2 ??m. Numerous flybys were performed at Saturn's second largest satellite Rhea, providing a nearly complete coverage with pixel-ground resolutions sufficient to analyze variations of spectral properties across Rhea's surface in detail. We present an overview of the VIMS observations obtained so far, as well as the analysis of the spectral properties identified in the VIMS spectra and their variations across its surface compared with spatially highly resolved Cassini ISS images and digital elevation models. Spectral variations measured across Rhea's surface are similar to the variations observed in the VIMS observations of its neighbor Dione, implying similar processes causing or at least inducing their occurrence. Thus, magnetospheric particles and dust impacting onto the trailing hemisphere appear to be responsible for the concentration of dark rocky/organic material and minor amounts of CO 2 in the cratered terrain on the trailing hemisphere. Despite the prominent spectral signatures of Rhea's fresh impact crater Inktomi, radiation effects were identified that also affect the H 2O ice-rich cratered terrain of the leading hemisphere. The concentration of H 2O ice in the vicinity of steep tectonic scarps near 270??W and geologically fresh impact craters implies that Rhea exhibits an icy crust at least in the upper few kilometers. Despite the evidence for past tectonic events, no indications of recent endogenically powered processes could be identified in the Cassini data. ?? 2011 Elsevier Ltd. All rights reserved.

  17. Optical properties of Titan's aerosols: comparison between DISR/Huygens observations and VIMS/Cassini solar occultation observations

    NASA Astrophysics Data System (ADS)

    Marmuse, Florian; Sotin, Christophe; Lawrence, Kenneth J.; Brown, Robert H.; Baines, Kevin; Buratti, Bonnie; Clark, Roger Nelson; Nicholson, Philip D.

    2016-10-01

    Titan, the only satellite with a dense atmosphere, presents a hydrocarbon cycle that includes the formation and sedimentation of organic aerosols. The optical properties of Titan's haze inferred from measurement of the Huygens probe were recently revisited by Doose et al. (Icarus, 2016). The present study uses the solar occultation observations in equatorial regions of Titan that have been acquired by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft to infer similar information in a broader wavelength range. Preliminary studies have proven the interest of those solar occultation data in the seven atmospheric windows to constrain the aerosol number density, but could not directly compare with the Descent Imager and Spectral Radiometer (DISR) data because models predict that the density profile vary with latitude. The present study compares the DISR measurements of aerosol extinction coefficients and the solar occultation data acquired by the VIMS instrument onboard Cassini. These sets of data differ in their acquisition method and time, spectral range, and altitude: the DISR measurements have been taken in 2005, along a vertical line of sight, in the visible spectral range (490-950nm) and under 140km of altitude. The relevant solar occultation data at equator have been acquired in 2009, along a horizontal line of sight, in the IR range (0.9-5.1µm), with sun light scanning all altitudes for a long enough wavelength, namely in the five-micron atmospheric window. These sets of data have been analyzed previously, separately and using different models. Here, we present a cross analysis of these sets of data, that allows us to test the different models describing the density profile of aerosols. In addition to providing wavelength dependence of the extinction coefficient, the comparison allows us to assess the impact of refraction in Titan's atmosphere. It also provides optical depth and scattering properties that are crucial information

  18. Effects of surface roughness with two scales on light scattering by hexagonal ice crystals large compared to the wavelength: DDA results

    NASA Astrophysics Data System (ADS)

    Collier, C. T.; Hesse, E.; Taylor, L.; Ulanowski, Z.; Penttilä, A.; Nousiainen, T.

    2016-10-01

    The effect of ice crystal surface roughness on light scattering by ice crystals which are large compared to the wavelength was studied, in particular changes to the 2D scattering patterns, azimuthally averaged phase functions, degree of linear polarisation patterns and asymmetry parameters for a range of orientations and roughness scales. It was found that roughness has an effect on light scattering by hexagonal prisms, particularly when the roughness features are of comparable size to the wavelength. The roughness model that has the most effect on light scattering takes account of more than one roughness scale. Rough geometry was implemented by a Gaussian roughness method that took roughness parameters derived from sand grains, which have been reported to be suitable proxies for rough ice crystals. Light scattering data for these geometries was computed using the ADDA discrete dipole approximation method.

  19. Remote sensing applications in marine science programs at VIMS

    NASA Technical Reports Server (NTRS)

    Gordon, H. H.; Penney, M. E.; Byrne, R. J.

    1974-01-01

    Scientists at the Virginia Institute of Marine Science (VIMS) utilized remote sensing in three programs: (1) tonal variations in imagery of wetlands; (2) use of the thermal infrared to delineate the discharge cooling water at the Virginia Electric and Power Company (VEPCO) nuclear power station on the James River; and (3) the use of aerial photography to determine the volume storage function for water in the marsh-bay complex fed by Wachapreague Inlet on the Eastern Shore of Virginia. Details of the investigations are given, along with significant results.

  20. Comparison of Verona Integron-Borne Metallo-β-Lactamase (VIM) Variants Reveals Differences in Stability and Inhibition Profiles

    PubMed Central

    Makena, Anne; Düzgün, Azer Ö.; Brem, Jürgen; McDonough, Michael A.; Rydzik, Anna M.; Abboud, Martine I.; Saral, Ayşegül; Çiçek, Ayşegül Ç.

    2015-01-01

    Metallo-β-lactamases (MBLs) are of increasing clinical significance; the development of clinically useful MBL inhibitors is challenged by the rapid evolution of variant MBLs. The Verona integron-borne metallo-β-lactamase (VIM) enzymes are among the most widely distributed MBLs, with >40 VIM variants having been reported. We report on the crystallographic analysis of VIM-5 and comparison of biochemical and biophysical properties of VIM-1, VIM-2, VIM-4, VIM-5, and VIM-38. Recombinant VIM variants were produced and purified, and their secondary structure and thermal stabilities were investigated by circular dichroism analyses. Steady-state kinetic analyses with a representative panel of β-lactam substrates were carried out to compare the catalytic efficiencies of the VIM variants. Furthermore, a set of metalloenzyme inhibitors were screened to compare their effects on the different VIM variants. The results reveal only small variations in the kinetic parameters of the VIM variants but substantial differences in their thermal stabilities and inhibition profiles. Overall, these results support the proposal that protein stability may be a factor in MBL evolution and highlight the importance of screening MBL variants during inhibitor development programs. PMID:26666919

  1. Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS

    USGS Publications Warehouse

    Baines, K.H.; Momary, T.W.; Fletcher, L.N.; Showman, A.P.; Roos-Serote, M.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    A high-speed cyclonic vortex centered on the north pole of Saturn has been revealed by the visual-infrared mapping spectrometer (VIMS) onboard the Cassini-Huygens Orbiter, thus showing that the tropospheres of both poles of Saturn are occupied by cyclonic vortices with winds exceeding 135 m/s. High-spatial-resolution (~200 km per pixel) images acquired predominantly under night-time conditions during Saturn's polar winter-using a thermal wavelength of 5.1 ??m to obtain time-lapsed imagery of discrete, deep-seated (>2.1-bar) cloud features viewed in silhouette against Saturn's internally generated thermal glow-show a classic cyclonic structure, with prograde winds exceeding 135 m/s at its maximum near 88.3?? (planetocentric) latitude, and decreasing to <30 m/s at 89.7?? near the vortex center and<20 m/s at 80.5??. High-speed winds, exceeding 125 m/s, were also measured for cloud features at depth near 76?? (planetocentric) latitude within the polar hexagon consistent with the idea that the hexagon itself, which remains nearly stationary, is a westward (retrograde) propagating Rossby wave - as proposed by Allison (1990, Science 247, 1061-1063) - with a maximum wave speed near 2-bars pressure of ~125 m/s. Winds are ~25 m/s stronger than observed by Voyager, suggesting temporal variability. Images acquired of one side of the hexagon in dawn conditions as the polar winter wanes shows the hexagon is still visible in reflected sunlight nearly 28 years since its discovery, that a similar 3-lane structure is observed in reflected and thermal light, and that the cloudtops may be typically lower in the hexagon than in nearby discrete cloud features outside of it. Clouds are well-correlated in visible and 5.1 ??m images, indicating little windshear above the ~2-bar level. The polar cyclone is similar in size and shape to its counterpart at the south pole; a primary difference is the presence of a small (<600 km in diameter) nearly pole-centered cloud, perhaps indicative of

  2. Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Baines, Kevin H.; Momary, Thomas W.; Fletcher, Leigh N.; Showman, Adam P.; Roos-Serote, Maarten; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.

    2009-12-01

    A high-speed cyclonic vortex centered on the north pole of Saturn has been revealed by the visual-infrared mapping spectrometer (VIMS) onboard the Cassini-Huygens Orbiter, thus showing that the tropospheres of both poles of Saturn are occupied by cyclonic vortices with winds exceeding 135 m/s. High-spatial-resolution (~200 km per pixel) images acquired predominantly under night-time conditions during Saturn's polar winter - using a thermal wavelength of 5.1 μm to obtain time-lapsed imagery of discrete, deep-seated (>2.1-bar) cloud features viewed in silhouette against Saturn's internally generated thermal glow - show a classic cyclonic structure, with prograde winds exceeding 135 m/s at its maximum near 88.3° (planetocentric) latitude, and decreasing to <30 m/s at 89.7° near the vortex center and<20 m/s at 80.5°. High-speed winds, exceeding 125 m/s, were also measured for cloud features at depth near 76° (planetocentric) latitude within the polar hexagon consistent with the idea that the hexagon itself, which remains nearly stationary, is a westward (retrograde) propagating Rossby wave - as proposed by Allison (1990, Science 247, 1061-1063) - with a maximum wave speed near 2-bars pressure of ~125 m/s. Winds are ~25 m/s stronger than observed by Voyager, suggesting temporal variability. Images acquired of one side of the hexagon in dawn conditions as the polar winter wanes shows the hexagon is still visible in reflected sunlight nearly 28 years since its discovery, that a similar 3-lane structure is observed in reflected and thermal light, and that the cloudtops may be typically lower in the hexagon than in nearby discrete cloud features outside of it. Clouds are well-correlated in visible and 5.1 μm images, indicating little windshear above the ~2-bar level. The polar cyclone is similar in size and shape to its counterpart at the south pole; a primary difference is the presence of a small (<600 km in diameter) nearly pole-centered cloud, perhaps indicative of

  3. Using the VIMS Dataset to Understand Titan’s Hydrologic Cycle Through Cloud Characterization

    NASA Astrophysics Data System (ADS)

    Corlies, Paul; Hayes, Alexander G.; Rodriguez, Sebastien; Adamkovics, Mate; Rojo, Patricio; Turtle, Elizabeth P.

    2015-11-01

    Along with Earth, Titan is the only body in our Solar System to possess an active hydrologic cycle. Monitoring how Titan’s methane-based hydrologic cycle varies with season over Saturn’s 29.7-year orbital period is essential for understanding its climate system.Using a newly developed radiative transfer pipeline, with updated HITRAN methane line parameters, we will present an ongoing analysis of the known cloud observations in the VIMS dataset. Although much work has gone into finding clouds in this dataset, little work has been done on understanding the characteristics of these clouds, barring a handful of individual analyses. Our pipeline allows for fast determination of these cloud characteristics including optical depth, altitude, and mean drop size. VIMS offers two advantages: providing consecutive observations of individual cloud systems to help diagnose formation mechanism and providing a decade long dataset to track seasonal variations, like those observed in cloud frequency and location. Characterizing clouds allows for an understanding of seasonally varying formation mechanisms, traces Titan’s atmospheric methane content across seasonal timescales, and can indicate clouds that could potentially have precipitated to provide context for interpreting observed surface features.We will also present an update on an ongoing ground based- cloud monitoring campaign. This campaign, begun in April 2014, has (nearly) continually monitored Titan on a variety of telescopes for the past 1.5 years. To date, no cloud activity has been observed, despite the variety in observation techniques that multiple telescopes allow. This is interesting because large cloud outbursts were observed during the equivalent point in southern summer and suggest a dichotomy in the seasonal dynamics of Titan’s atmosphere. Understanding when and with what frequency clouds begin to form in the north is crucial to understanding Titan’s hydrologic cycle on seasonal time scales.

  4. Spectral changes associated with rain on Titan: observations by VIMS

    NASA Astrophysics Data System (ADS)

    Buratti, B. J.; Dalba, P. A.; Barnes, J.; Baines, K. H.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.; Sotin, C.

    2012-04-01

    Titan has an erosional cycle similar to that on the Earth, with solid, liquid, and gaseous methane taking the place of the Earth’s water. Lakes and ponds, drainage and fluvial features, and clouds all suggest that rain is falling on Titan. A darkening event near clouds covering the Huygens landing site, followed by a return to the previous state, strongly suggested rainfall followed by evaporation (Turtle et al., 2011). The Cassini Visual infrared Mapping Spectrometer (VIMS) obtains medium resolution spectra in the 0.35-5.1 μm spectral region, which includes several atmospheric “windows” that offer glimpses of Titan’s surface. The albedo of the surface can be measured in these windows, and some compositional information, including changes through time, can be derived. VIMS observed an area near 15º south latitude and 330º longitude at two separate times: in August 2009 during T61 and in May 2011 during T76. A spectral analysis of this region, including compensation for varying atmospheric path lengths, shows substantial spectral changes in the two and five micron atmospheric windows. A comparison of the changes with that expected from the deposition and later evaporation of liquid methane or another hydrocarbon shows them to be consistent with rain on Titan. Ackowledgements: This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration. Copyright 2012 all rights reserved. References: Turtle, E. P. et al. (2011) Science 331, 1414.

  5. Cryovolcanism on Titan: New results from Cassini RADAR and VIMS

    NASA Astrophysics Data System (ADS)

    Lopes, R. M. C.; Kirk, R. L.; Mitchell, K. L.; Legall, A.; Barnes, J. W.; Hayes, A.; Kargel, J.; Wye, L.; Radebaugh, J.; Stofan, E. R.; Janssen, M. A.; Neish, C. D.; Wall, S. D.; Wood, C. A.; Lunine, J. I.; Malaska, M. J.

    2013-03-01

    The existence of cryovolcanic features on Titan has been the subject of some controversy. Here we use observations from the Cassini RADAR, including Synthetic Aperture Radar (SAR) imaging, radiometry, and topographic data as well as compositional data from the Visible and Infrared Mapping Spectrometer (VIMS) to reexamine several putative cryovolcanic features on Titan in terms of likely processes of origin (fluvial, cryovolcanic, or other). We present evidence to support the cryovolcanic origin of features in the region formerly known as Sotra Facula, which includes the deepest pit so far found on Titan (now known as Sotra Patera), flow-like features (Mohini Fluctus), and some of the highest mountains on Titan (Doom and Erebor Montes). We interpret this region to be a cryovolcanic complex of multiple cones, craters, and flows. However, we find that some other previously supposed cryovolcanic features were likely formed by other processes. Cryovolcanism is still a possible formation mechanism for several features, including the flow-like units in Hotei Regio. We discuss implications for eruption style and composition of cryovolcanism on Titan. Our analysis shows the great value of combining data sets when interpreting Titan's geology and in particular stresses the value of RADAR stereogrammetry when combined with SAR imaging and VIMS.

  6. VIS-IR spectrograms of Saturn's rings retrieved from Cassini-VIMS radial mosaics

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Nicholson, P.; Hedmann, M. M.; Clark, R. N.; Brown, R. H.; Cerroni, P.

    2011-10-01

    Context: Cassini-VIMS has harvested a large number of Saturn's rings radial mosaics at very different observation geometries. Aims: This work is focused on the retrieval of rings average composition (water ice and red cromophores), regolith grain sizes and photometric parameters. Method: We have implemented a procedure to build ring spectrograms, e.g., 2D arrays that contain the full spectral (0.35 - 5.0 μm) and spatial (from 73.500 to 141.375 km) information sampled at 400 km/bin spatial resolution. This processing is applied to several mosaics acquired at different illumination phases (12° to 136°) and opening angles (-21° to +5°). Results: Ring spectra show reddening at VIS wavelengths while maintaining a strong similarity to water ice in the IR. Differences both in VIS reddening, water ice abundance and grain sizes are retrieved across different rings regions. Conclusions: Two important findings are that 1) both VIS reddening and water ice band depths increase at high phases, thus indicating that the red contaminant is intimately mixed in water ice grains; 2) typical regolith grain sizes are between 10-40 μm in the C ring, 40-60 μm in the Cassini Division (CD) and >100 μm in the A and B rings.

  7. MULTI-WAVELENGTH OBSERVATIONS OF THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES WITH AIA/SDO. I. UNIVERSAL SCALING LAWS OF SPACE AND TIME PARAMETERS

    SciTech Connect

    Aschwanden, Markus J.; Zhang, Jie; Liu, Kai E-mail: jzhang7@gmu.edu

    2013-09-20

    We extend a previous statistical solar flare study of 155 GOES M- and X-class flares observed with AIA/SDO to all seven coronal wavelengths (94, 131, 171, 193, 211, 304, and 335 Å) to test the wavelength dependence of scaling laws and statistical distributions. Except for the 171 and 193 Å wavelengths, which are affected by EUV dimming caused by coronal mass ejections (CMEs), we find near-identical size distributions of geometric (lengths L, flare areas A, volumes V, and fractal dimension D{sub 2}), temporal (flare durations T), and spatio-temporal parameters (diffusion coefficient κ, spreading exponent β, and maximum expansion velocities v{sub max}) in different wavelengths, which are consistent with the universal predictions of the fractal-diffusive avalanche model of a slowly driven, self-organized criticality (FD-SOC) system, i.e., N(L)∝L {sup –3}, N(A)∝A {sup –2}, N(V)∝V {sup –5/3}, N(T)∝T {sup –2}, and D{sub 2} = 3/2, for a Euclidean dimension d = 3. Empirically, we find also a new strong correlation κ∝L {sup 0.94±0.01} and the three-parameter scaling law L∝κ T {sup 0.1}, which is more consistent with the logistic-growth model than with classical diffusion. The findings suggest long-range correlation lengths in the FD-SOC system that operate in the vicinity of a critical state, which could be used for predictions of individual extreme events. We find also that eruptive flares (with accompanying CMEs) have larger volumes V, longer flare durations T, higher EUV and soft X-ray fluxes, and somewhat larger diffusion coefficients κ than confined flares (without CMEs)

  8. Multi-wavelength Observations of the Spatio-temporal Evolution of Solar Flares with AIA/SDO. I. Universal Scaling Laws of Space and Time Parameters

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.; Zhang, Jie; Liu, Kai

    2013-09-01

    We extend a previous statistical solar flare study of 155 GOES M- and X-class flares observed with AIA/SDO to all seven coronal wavelengths (94, 131, 171, 193, 211, 304, and 335 Å) to test the wavelength dependence of scaling laws and statistical distributions. Except for the 171 and 193 Å wavelengths, which are affected by EUV dimming caused by coronal mass ejections (CMEs), we find near-identical size distributions of geometric (lengths L, flare areas A, volumes V, and fractal dimension D 2), temporal (flare durations T), and spatio-temporal parameters (diffusion coefficient κ, spreading exponent β, and maximum expansion velocities v max) in different wavelengths, which are consistent with the universal predictions of the fractal-diffusive avalanche model of a slowly driven, self-organized criticality (FD-SOC) system, i.e., N(L)vpropL -3, N(A)vpropA -2, N(V)vpropV -5/3, N(T)vpropT -2, and D 2 = 3/2, for a Euclidean dimension d = 3. Empirically, we find also a new strong correlation κvpropL 0.94 ± 0.01 and the three-parameter scaling law Lvpropκ T 0.1, which is more consistent with the logistic-growth model than with classical diffusion. The findings suggest long-range correlation lengths in the FD-SOC system that operate in the vicinity of a critical state, which could be used for predictions of individual extreme events. We find also that eruptive flares (with accompanying CMEs) have larger volumes V, longer flare durations T, higher EUV and soft X-ray fluxes, and somewhat larger diffusion coefficients κ than confined flares (without CMEs).

  9. Equinoctial Activity Over Titan Dune Fields Revealed by Cassini/vims

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Le Mouelic, S.; Barnes, J. W.; Hirtzig, M.; Rannou, P.; Sotin, C.; Brown, R. H.; Bow, J.; Vixie, G.; Cornet, T.; Bourgeois, O.; Narteau, C.; Courrech Du Pont, S.; Le Gall, A.; Reffet, E.; Griffith, C. A.; Jaumann, R.; Stephan, K.; Buratti, B. J.; Clark, R. N.; Baines, K. H.; Nicholson, P. D.; Coustenis, A.

    2012-12-01

    Titan, the largest satellite of Saturn, is the only satellite in the solar system with a dense atmosphere. The close and continuous observations of Titan by the Cassini spacecraft, in orbit around Saturn since July 2004, bring us evidences that Titan troposphere and low stratosphere experience an exotic, but complete meteorological cycle similar to the Earth hydrological cycle, with hydrocarbons evaporation, condensation in clouds, and rainfall. Cassini monitoring campaigns also demonstrate that Titan's cloud coverage and climate vary with latitude. Titan's tropics, with globally weak meteorological activity and widespread dune fields, seem to be slightly more arid than the poles, where extensive and numerous liquid reservoirs and sustained cloud activity have been discovered. Only a few tropo-spheric clouds have been observed at Titan's tropics during the southern summer. As equinox was approaching (in August 2009), they occurred more frequently and appeared to grow in strength and size. We present here the observation of intense brightening at Titan's tropics, very close to the equinox. These detections were conducted with the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini. We will discuss the VIMS images of the three individual events detected so far, observed during the Titan's flybys T56 (22 May 2009), T65 (13 January 2010) and T70 (21 June 2010). T56, T65 and T70 observations show an intense and transient brighten-ing of large regions very close to the equator, right over the extensive dune fields of Senkyo, Belet and Shangri-La. They all appear spectrally and morphologically different from all transient surface features or atmospheric phenomena previously reported. Indeed, these events share in particular a strong brightening at wavelengths greater than 2 μm (especially at 5 μm), making them spectrally distinct from the small tropical clouds observed before the equinox and the large storms observed near the equator in September and October

  10. Latitudinal variations in Titan's methane and haze from Cassini VIMS observations

    USGS Publications Warehouse

    Penteado, P.F.; Griffith, C.A.; Tomasko, M.G.; Engel, S.; See, C.; Doose, L.; Baines, K.H.; Brown, R.H.; Buratti, B.J.; Clark, R.; Nicholson, P.; Sotin, C.

    2010-01-01

    We analyze observations taken with Cassini's Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60??S and 40??N. The methane variation was measured primarily from its absorption band at 0.61 ??m, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan's 0.4-1.6 ??m spectra, which sample Titan's atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20??S and 10??S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60??S and 40??N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27??S and 19??N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan's visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane

  11. VIMS spectral mapping observations of Titan during the Cassini prime mission

    USGS Publications Warehouse

    Barnes, J.W.; Soderblom, J.M.; Brown, R.H.; Buratti, B.J.; Sotin, C.; Baines, K.H.; Clark, R.N.; Jaumann, R.; McCord, T.B.; Nelson, R.; Le, Mouelic S.; Rodriguez, S.; Griffith, C.; Penteado, P.; Tosi, F.; Pitman, K.M.; Soderblom, L.; Stephan, K.; Hayne, P.; Vixie, G.; Bibring, J.-P.; Bellucci, G.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Langevin, Y.; Matson, D.L.; Nicholson, P.D.; Sicardy, B.

    2009-01-01

    This is a data paper designed to facilitate the use of and comparisons to Cassini/visual and infrared mapping spectrometer (VIMS) spectral mapping data of Saturn's moon Titan. We present thumbnail orthographic projections of flyby mosaics from each Titan encounter during the Cassini prime mission, 2004 July 1 through 2008 June 30. For each flyby we also describe the encounter geometry, and we discuss the studies that have previously been published using the VIMS dataset. The resulting compliation of metadata provides a complementary big-picture overview of the VIMS data in the public archive, and should be a useful reference for future Titan studies. ?? 2009 Elsevier Ltd.

  12. Use of virtual, interactive, musculoskeletal system (VIMS) in modeling and analysis of shoulder throwing activity.

    PubMed

    Lin, Hwai-Ting; Nakamura, Yasuo; Su, Fong-Chin; Hashimoto, Jun; Nobuhara, Katsuya; Chao, Edmund Y S

    2005-06-01

    Our purpose in this study was to apply the virtual, interactive, musculoskeletal system (VIMS) software for modeling and biomechanical analysis of the glenohumeral joint during a baseball pitching activity. The skeletal model was from VIMS library and muscle fiber attachment sites were derived from the visible human dataset. The muscular moment arms and function changes are mainly due to the large humeral motion involved during baseball pitching. The graphic animation of the anatomic system using VIMS software is an effective tool to model and visualize the complex anatomical structure of the shoulder for biomechanical analysis.

  13. Multiemission wavelength picosecond time-resolved fluorescence decay data obtained on the millisecond time scale: application to protein:DNA interactions and protein-folding reactions

    NASA Astrophysics Data System (ADS)

    Beechem, Joseph M.

    1992-04-01

    One of the major aspects of fluorescence spectroscopy which differentiates this technique from many other spectroscopic approaches is the inherent multidimensional nature of the data. For instance, the basic pulsed-laser fluorescence data set is characterized by fluorescence versus: emission wavelength, polarization state (parallel and perpendicular intensities), time of emission (picoseconds to nanoseconds), and time of biological reaction (milliseconds to minutes). Usually, this six-dimensional data set is obtained piecemeal, single dimension at a time; often complete data sets are not even collected. This is especially true of the biological time scale axis. Data acquisition times for picosecond decay data are typically seconds to minutes, and, therefore, it has not been generally possible to perform this experiment in a kinetic mode. What is described in this report is the construction of a parallel multichannel time-correlated single-photon counting (TCSPC) fluorometer which is capable of simultaneous collection of: fluorescence vs. picosecond to nanosecond time vs. emission wavelength vs. polarization state vs. millisecond to second time. Use is made of two multi-anode microchannel plate detectors, each obtaining data at two different polarization states, six different emission wavelengths, along 12 independent TCSPC channels. This instrument is interfaced to a three-syringe stepper motor controlled stop-flow apparatus, and picosecond decay data along all of these channels is stored and collected by two 33 MHz 80486 computers at rates approaching 1200 - 12000 data sets per second.

  14. Scaling single-wavelength optical interconnects to 180 Gb/s with PAM-M and pulse shaping

    NASA Astrophysics Data System (ADS)

    Dris, Stefanos; Bakopoulos, Paraskevas; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

    2016-03-01

    Faced with surging datacenter traffic demand, system designers are turning to multi-level optical modulation with direct detection as the means of reaching 100 Gb/s in a single optical lane; a further upgrade to 400 Gb/s is envisaged through wavelength-multiplexing of multiple 100 Gb/s strands. In terms of modulation formats, PAM-4 and PAM-8 are considered the front-runners, striking a good balance between bandwidth-efficiency and implementation complexity. In addition, the emergence of energy-efficient, high-speed CMOS digital-to-analog converters (DACs) opens up new possibilities: Spectral shaping through digital filtering will allow squeezing even more data through low-cost, low-bandwidth electro-optic components. In this work we demonstrate an optical interconnect based on an EAM that is driven directly with sub-volt electrical swing by a 65 GSa/s arbitrary waveform generator (AWG). Low-voltage drive is particularly attractive since it allows direct interfacing with the switch/server ASIC, eliminating the need for dedicated, power-hungry and expensive electrical drivers. Single-wavelength throughputs of 180 and 120 Gb/s are experimentally demonstrated with 60 Gbaud optical PAM-8 and PAM-4 respectively. Successful transmission over 1250 m SMF is achieved with direct-detection, using linear equalization via offline digital signal processing in order to overcome the strong bandwidth limitation of the overall link (~20 GHz). The suitability of Nyquist pulse shaping for optical interconnects is also investigated experimentally with PAM-4 and PAM-8, at a lower symbol rate of 40 Gbaud (limited by the sampling rate of the AWG). To the best of our knowledge, the rates achieved are the highest ever using optical PAM-M formats.

  15. Uplift of the South African Plateau: mantle-scale deformation, long wavelength relief growth and offshore sediment budget

    NASA Astrophysics Data System (ADS)

    Guillocheau, François; Dauteuil, Olivier; Baby, Guillaume; Robin, Cécile

    2013-04-01

    The South African Plateau is one of the largest very long wavelength relief (x1000 km) of the world that could be related to mantle dynamics and the effect of the African superplume. Unfortunately, the timing of the uplift and the different steps of the relief growth are still debated with a Late Cretaceous uplift scenario and an Oligocene one. Whatever model, few attentions were paid to the evolution of the overall geomorphic system, from the upstream erosional system to the downstream depositional system. This study is based, onshore, on the mapping and chronology of all the macroforms (weathering surfaces and associated alterites, pediments and pediplains, incised rivers, wave-cut platforms) dated by intersection with the few preserved sediments and the volcanics (mainly kimberlites pipes) and, offshore, on a more classical dataset of seismic lines and petroleum wells (characterization and dating of forced regression, sediment volume measurement, etc..). The main result of this study is that the South African Plateau is an old Late Cretaceous Plateau reactivated during Paleogene times and fossilized since the Middle Miocene. • During Late Cretaceous, in a semiarid climatic setting, the main uplift occurred from the east (around 95 Ma) to the west (around 75 Ma) and could result from the migration of the African plate over the African superplume: This is the paroxysm of the erosion with the growth of a large delta offshore present-day Orange River mouth (sedimentation rate around 100 000 km3/Ma). • During Paleocene - Mid Eocene times, in more humid conditions and in response to a more subtle long wavelength deformation, pedimentation occurred mainly localised along Cape Fold Belt feeding a large delta offshore western Cape Peninsula. During Mid Eocene times, all those landscapes are fossilized and weathered by laterites. • Late Eocene and Oligocene is the second period of uplift of the Plateau, localised along its Indian Ocean side (Drackensberg Moutains

  16. VizieR Online Data Catalog: The KepVIM catalog (Makarov+, 2016)

    NASA Astrophysics Data System (ADS)

    Makarov, V. V.; Goldin, A.

    2016-07-01

    The algorithm described in section 4 was applied to the entire collection of "long-cadence" files archived in the MAST for the principal Kepler mission. A single variability-induced motion (VIM) detection corresponds to a complete data set for a given target collected during one quarter. Therefore, a single target can generate up to 17 VIM detections in the catalog. (2 data files).

  17. Titan's aerosol optical properties with VIMS observations at the limb of Titan

    NASA Astrophysics Data System (ADS)

    Rannou, Pascal; Seignovert, Benoit; Lavvas, Panayotis; Lemouelic, Stéphane; Sotin, Christophe

    2015-11-01

    The study of Titan properties with remote sensing relies on a good knowledge of the atmosphere properties. The in-situ observations made by Huygens combined with recent advances in the definition of methane properties enable to model and interpret observations with a very good accuracy. Thanks to these progresses, we can analyze in this work the observations made at the limb of Titan in order to retrieve information on the haze properties as its vertical profiles but also the spectral behaviour between 0.88 and 5.2 μm.To study the haze layer and more generally the source of opacities in the stratosphere, we use som observation made at the limbe of Titan by the VIMS instrument onboard Cassini. We used a model in spherical geometry and in single scattering, and we accounted for the multiple scattering with a parallel plane model that evaluate the multiple scattering source function at the plane of the limb.Our scope is to retrieve informations about the vertical distribution of the haze, its spectral properties, but also to obtain details about the shape of the methane windows to disantangle the role of the methane and of the aerosols.We started our study at the latitude of 55°N, with a image taken in 2006 with a relatively high spatial resolution (for VIMS). Our preliminary results shows the spectral properties of the aerosols are the same whatever the altitude. This is a consequence of the large scale mixing. From limb profile between 0.9 and 5.2 μm, we can probe the haze layer from about 500 km (at 0.9 μm) to the ground (at 5.2 μm). We find that the vertical profile of the haze layer shows three distinct scale heights with transitions around 250 km and 350 km. We also clearly a transition around 70-90 km that may be due to the top of a condensation layer.

  18. Emitted Power of Jupiter Based on Cassini CIRS and VIMS Observations

    NASA Technical Reports Server (NTRS)

    Li, Liming; Baines, Kevin H.; Smith, Mark A.; West, Robert A.; Perez-Hoyos, Santiago; Trammel, Harold J.; Simon-Miller, Amy A.; Conrath, Barney J.; Gierasch, Peter J.; Orton, Glenn S.; Nixon, Conor A.; Filachionne, Gianrico; Fry, Patrick M.; Momary, Thomas W.

    2012-01-01

    The emitted power of Jupiter and its meridional distribution are determined from observations by the Composite Infrared Spectrometer (CIRS) and Visual and Infrared Spectrometer (VIMS) onboard Cassini during its flyby en route to Saturn in late 2000 and early 2001. Jupiter's global- average emitted power and effective temperature are measured to be 14.10+/-0.03 W/sq m and 125.57+/-0.07 K, respectively. On a global scale, Jupiter's 5-micron thermal emission contributes approx. 0.7+/-0.1 % to the total emitted power at the global scale, but it can reach approx. 1.9+/-0.6% at 15degN. The meridional distribution of emitted power shows a significant asymmetry between the two hemispheres with the emitted power in the northern hemisphere 3.0+/-0.3% larger than that in the southern hemisphere. Such an asymmetry shown in the Cassini epoch (2000-01) is not present during the Voyager epoch (1979). In addition, the global-average emitted power increased approx. 3.8+/-1.0% between the two epochs. The temporal variation of Jupiter's total emitted power is mainly due to the warming of atmospheric layers around the pressure level of 200 mbar. The temporal variation of emitted power was also discovered on Saturn (Li et al., 2010). Therefore, we suggest that the varying emitted power is a common phenomenon on the giant planets.

  19. Emitted Power Of Jupiter Based On Cassini CIRS And VIMS Observations

    NASA Technical Reports Server (NTRS)

    Li, Liming; Baines, Kevin H.; Smith, Mark A.; West, Robert A.; Perez-Hoyos, Santiago; Trammel, Harold J.; Simon-Miller, Amy A.; Conrath, Barney J.; Gierasch, Peter J.; Orton, Glenn S.; Nixon, Conor A.; Filacchione, Gianrico; Fry, Patrick M.; Momary, Thomas W.

    2012-01-01

    The emitted power of Jupiter and its meridional distribution are determined from observations by the Composite Infrared Spectrometer (CIRS) and Visual and Infrared Spectrometer (VIMS) onboard Cassini during its flyby en route to Saturn in late 2000 and early 2001. Jupiter's global- average emitted power and effective temperature are measured to be 14.10+/-0.03 W/sq m and 125.57+/-0.07 K, respectively. On a global scale, Jupiter's 5-micron thermal emission contributes approx. 0.7+/-0.1 % to the total emitted power at the global scale, but it can reach approx. 1.9+/-0.6% at 15degN. The meridional distribution of emitted power shows a significant asymmetry between the two hemispheres with the emitted power in the northern hemisphere 3.0+/-0.3% larger than that in the southern hemisphere. Such an asymmetry shown in the Cassini epoch (2000-01) is not present during the Voyager epoch (1979). In addition, the global-average emitted power increased approx. 3.8+/-1.0% between the two epochs. The temporal variation of Jupiter's total emitted power is mainly due to the warming of atmospheric layers around the pressure level of 200 mbar. The temporal variation of emitted power was also discovered on Saturn (Li et al., 2010). Therefore, we suggest that the varying emitted power is a common phenomenon on the giant planets.

  20. Global mapping and characterization of Titan's dune fields with Cassini: Correlation between RADAR and VIMS observations

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Garcia, A.; Lucas, A.; Appéré, T.; Le Gall, A.; Reffet, E.; Le Corre, L.; Le Mouélic, S.; Cornet, T.; Courrech du Pont, S.; Narteau, C.; Bourgeois, O.; Radebaugh, J.; Arnold, K.; Barnes, J. W.; Stephan, K.; Jaumann, R.; Sotin, C.; Brown, R. H.; Lorenz, R. D.; Turtle, E. P.

    2014-02-01

    Vast fields of linear dunes have been observed in the equatorial regions of Titan, Saturn's largest moon. As the Cassini mission, in orbit around Saturn since July 2004 and extended until May 2017, carries on, the high-resolution coverage of Titan's surface increases, revealing new dune fields and allowing refinements in the examination of their properties. In this paper, we present the joint analysis of Cassini's microwave and infrared global scale observations of Titan. Integrating within an up-to-date global map of Titan all the Cassini RADAR and VIMS (Visual and Infrared Mapping Spectrometer) images - the latter being empirically corrected for atmospheric scattering and surface photometry, from July 2004 through July 2013 and June 2010 respectively, we found very good qualitative and quantitative spatial matching between the geographic distribution of the dune fields and a specific infrared spectral unit (namely the “dark brown” unit). The high degree of spatial correlation between dunes and the “dark brown” unit has important implications for Titan's geology and climate. We found that RADAR-mapped dunes and the “dark brown” unit are similarly confined within the equatorial belt (±30° in latitudes) with an equivalent distribution with latitude, suggesting an increasing sediment availability and mobility at Titan's tropics relative to higher latitudes, compatible with the lower ground humidity predicted in equatorial regions by General Circulation Models. Furthermore, the strong correlation between RADAR-mapped dunes and the VIMS “dark brown” unit (72%) allows us to better constrain the total surface area covered by dune material, previously estimated from the extrapolation of the RADAR observations alone. According to our calculations, dune material cover 17.5 ± 1.5% of Titan's surface area, equivalent to a total surface area of 14.6 ± 1.2 million km2 (˜1.5 times the surface area of Earth's Sahara desert). The VIMS “dark brown

  1. Characterization of the New Metallo-β-Lactamase VIM-13 and Its Integron-Borne Gene from a Pseudomonas aeruginosa Clinical Isolate in Spain▿

    PubMed Central

    Juan, Carlos; Beceiro, Alejandro; Gutiérrez, Olivia; Albertí, Sebastián; Garau, Margalida; Pérez, José L.; Bou, Germán; Oliver, Antonio

    2008-01-01

    During a survey conducted to evaluate the incidence of class B carbapenemase (metallo-β-lactamase [MBL])-producing Pseudomonas aeruginosa strains from hospitals in Majorca, Spain, five clinical isolates showed a positive Etest MBL screening test result. In one of them, strain PA-SL2, the presence of a new blaVIM derivative (blaVIM-13) was detected by PCR amplification with blaVIM-1-specific primers followed by sequencing. The blaVIM-13-producing isolate showed resistance to all β-lactams (except aztreonam), gentamicin, tobramycin, and ciprofloxacin. VIM-13 exhibited 93% and 88% amino acid sequence identities with VIM-1 and VIM-2, respectively. blaVIM-13 was cloned in parallel with blaVIM-1, and the resistance profile conferred was analyzed both in Escherichia coli and in P. aeruginosa backgrounds. Compared to VIM-1, VIM-13 conferred slightly higher levels of resistance to piperacillin and lower levels of resistance to ceftazidime and cefepime. VIM-13 and VIM-1 were purified in parallel as well, and their kinetic parameters were compared. The kcat/Km ratios for the antibiotics mentioned above were in good agreement with the MIC data. Furthermore, EDTA inhibited the activity of VIM-13 approximately 25 times less than it inhibited the activity of VIM-1. VIM-13 was harbored in a class 1 integron, along with a new variant (Ala108Thr) of the aminoglycoside-modifying enzyme encoding gene aacA4, which confers resistance to gentamicin and tobramycin. Finally, the VIM-13 integron was apparently located in the chromosome, since transformation and conjugation experiments consistently yielded negative results and the blaVIM-13 probe hybridized only with the genomic DNA. PMID:18644957

  2. Identification of VIM-2-Producing Pseudomonas aeruginosa from Tanzania Is Associated with Sequence Types 244 and 640 and the Location of blaVIM-2 in a TniC Integron

    PubMed Central

    Moyo, Sabrina; Haldorsen, Bjørg; Aboud, Said; Blomberg, Bjørn; Maselle, Samuel Y.; Sundsfjord, Arnfinn; Langeland, Nina

    2014-01-01

    Epidemiological data on carbapenemase-producing Gram-negative bacteria on the African continent are limited. Here, we report the identification of VIM-2-producing Pseudomonas aeruginosa isolates in Tanzania. Eight out of 90 clinical isolates of P. aeruginosa from a tertiary care hospital in Dar es Salaam were shown to harbor blaVIM-2. The blaVIM-2-positive isolates belonged to two different sequence types (ST), ST244 and ST640, with blaVIM-2 located in an unusual integron structure lacking the 3′ conserved region of qacΔE1-sul1. PMID:25331700

  3. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure

    NASA Astrophysics Data System (ADS)

    Spilker, L.; Deau, E.; Morishima, R.; Filacchione, G.; Hedman, M.; Nicholson, P.; Colwell, J.; Bradley, T.

    2012-04-01

    A great deal can be learned about the nature of Saturn's ring particles and their regoliths by modeling the changes in brightness, color and temperature with changing viewing geometry over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly being studied using scans of the lit and unlit main rings (A, B, C and Cassini Division) at multiple geometries and solar elevations. Using multi-wavelength data sets allow us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation. With the high spatial resolution of the Cassini data it is now possible to analyze these effects at smaller spatial scales and characterize regions such as the C ring plateaus and ringlets, where albedo differences may be present. In the CIRS data, over a range of solar elevations from -23 degrees to -8 degrees, the bulk of the temperature variations are confined primarily to phase angle. Only small temperature differences are observed with changing spacecraft elevation. Similar behavior is seen in the ISS color data. Color and temperature dependence with changing solar elevation angle are also observed. VIMS observations show that the IR ice absorption band depths are (almost) independent of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces

  4. Compositional radial variability in the Saturn's system observed by Cassini-VIMS (INVITED) (Invited)

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Clark, R. N.; Brown, R. H.; Cuzzi, J. N.; Buratti, B. J.; Coradini, A.; Lunine, J. I.; Cerroni, P.; Tosi, F.; Ciarniello, M.; Cruikshank, D. P.; Jaumann, R.; Nicholson, P. D.; Stephan, K.; Nelson, R.; Baines, K. H.

    2010-12-01

    From ~2200 disk-integrated observations of the moons and several radial mosaics of the rings acquired by Cassini-VIMS, we have found very striking differences among the various objects in the Saturn system, ranging from the almost uncontaminated and water ice-rich surfaces of Enceladus and Calypso to the metal/organic-rich and red surfaces of Iapetus’ leading hemisphere and Phoebe. In this framework, we have investigated the relationships between the satellite surface composition, orbital distance from Saturn, and average density. In the F ring environment, the inner satellites (Prometheus, Pandora, Janus and Epimetheus) have average surface water ice abundances similar to particles in the C ring and CD but with much less reddening contaminant. Although their orbits are close to the F-ring, Prometheus and Pandora have very evident differences in surface composition: Prometheus is very water ice-rich but at the same time very red at VIS wavelengths. These properties make it very similar to A-B ring particles while Pandora is bluer. Moving outward, the effects of E ring particles, generated by Enceladus plumes become evident as they contaminate surfaces from Mimas to Rhea. We have found some differences between the Lagrangian moons of Tethys: Calypso is much more water ice-rich and bluer with respect to Telesto. Among the outer satellites, moving from Hyperion, to Iapetus and Phoebe, a linear trend is observed relating the decrease of water ice to reddening, with Hyperion resulting as the reddest object of the population. As a further step, we have investigated how these surface properties are correlated with the average densities and dimensions of the moons. Mid-sized icy satellites are in a transition regime, between the high pressure/high density ice phases of Titan and the high porosity/irregular shapes of the minor moons and Hyperion. Low-density (0.5-1.0 g cm-3) satellites show different trends with Prometheus, Pandora and Calypso characterized by high

  5. Constraints On Titan's Surface Composition From 5-µm Cassini/VIMS Observations

    NASA Astrophysics Data System (ADS)

    Hayne, Paul; McCord, T. B.; Combe, J.; Hansen, G.

    2007-10-01

    Observing Titan's surface is complicated by the strong absorbing and scattering properties of the atmosphere. Fortunately, there exist several "windows” between methane absorptions, where the surface is viewable. The 5-µm window is least affected by haze scattering, although the signal is low in this spectral region. We present the results of an extensive search for absorption features in the VIMS hyperspectral data using a statistically unbiased band-fitting algorithm. The approach is optimized for finding narrow absorption lines in the 5-µm window. If a candidate absorption meets any of the following criteria, it is deemed significant: i) The feature is apparent above the noise in the average of all pixels in a dataset. ii) Contiguous subset(s) of an image contain a higher concentration of pixels showing the feature than predicted by the data noise statistics. This excess should be observed consistently in different images containing the region. iii) The feature is spatially correlated with a morphologically and/or spectrally distinct unit, again consistent through time. Using these criteria, one statistically significant absorption is found: near 4.9 µm, it is strongly correlated with the Tui Regio bright anomaly (described by Barnes et al., GRL, 2005). The wavelength location and strength of this absorption are consistent with CO2 ice, likely complexed with other materials such as H2O ice (McCord et al., this meeting). Other localized regions of Titan also show the feature, notably Omacatl Macula (Hayne et al., AGU abstract, 2006). Not finding any other absorptions, for example due to organics predicted to precipitate on Titan's surface (Wilson et al., JGR, 2003), we can place tentative upper limits on the spatial coverage by these hypothetical constituents. The methods described are also being applied to other icy Saturnian satellites.

  6. Wave constraints for Titan's Jingpo Lacus and Kraken Mare from VIMS specular reflection lightcurves

    USGS Publications Warehouse

    Barnes, J.W.; Soderblom, J.M.; Brown, R.H.; Soderblom, L.A.; Stephan, K.; Jaumann, R.; Le Mouélic, Stéphane; Rodriguez, S.; Sotin, C.; Buratti, B.J.; Baines, K.H.; Clark, R.N.; Nicholson, P.D.

    2011-01-01

    Stephan et al. (Stephan, K. et al. [2010]. Geophys. Res. Lett. 37, 7104-+.) first saw the glint of sunlight specularly reflected off of Titan's lakes. We develop a quantitative model for analyzing the photometric lightcurve generated during a flyby in which the specularly reflected light flux depends on the fraction of the solar specular footprint that is covered by liquid. We allow for surface waves that spread out the geographic specular intensity distribution. Applying the model to the VIMS T58 observations shows that the waves on Jingpo Lacus must have slopes of no greater than 0.15??, two orders of magnitude flatter than waves on Earth's oceans. Combining the model with theoretical estimates of the intensity of the specular reflection allows a tighter constraint on the waves: <0.05?? Residual specular signal while the specular point lies on land implies that either the land is wetted, the wave slope distribution is non-Gaussian, or that 5% of the land off the southwest edge of Jingpo Lacus is covered in puddles. Another specular sequence off of Kraken Mare acquired during Cassini's T59 flyby shows rapid flux changes that the static model cannot reproduce. Points just 1. min apart vary in flux by more than a factor of two. The present dataset does not uniquely determine the mechanism causing these rapid changes. We suggest that changing wind conditions, kilometer-wavelength waves, or moving clouds could account for the variability. Future specular observations should be designed with a fast cadence, at least 6 points per minute, in order to differentiate between these hypotheses. Such new data will further constrain the nature of Titan's lakes and their interactions with Titan's atmosphere. ?? 2010 Elsevier Inc.

  7. VIMS Near-Infrared Imaging and Spectra of Precipitation-Associated Surface Changes

    NASA Astrophysics Data System (ADS)

    Barnes, Jason W.; Buratti, Bonnie J.; Turtle, Elizabeth P.; Bow, Jacob; Dalba, Paul A.; Perry, Jason; Brown, Robert H.; Rodriguez, Sebastien; LeMouelic, Stephane; Baines, Kevin H.; Sotin, Christophe; Lorenz, Ralph D.; Malaska, Michael J.; McCord, Thomas B.; Clark, Roger N.; Jaumann, Ralf; Hayne, Paul; Nicholson, Philip D.; Soderblom, Jason M.; Soderblom, Laurence A.

    2012-04-01

    Cassini ISS saw large-scale surface darkenings in the wake of a tropical cloudburst event in 2010 September. In concert with the abstract by Turtle et al., in this presentation we show that weeks to months after darkening the surfaces did not revert to their pre-cloudburst brightness, but rather became brighter. VIMS observations of four distinct areas show these brightenings: Yalaing Terra, Hetpet Regio, Concordia Regio, and Adiri. Each study area brightened within each near-infrared atmospheric window, though not equally. In each case the brightened areas fade to their original spectra over a timescale of about a year. This rapid reversion time is inconsistent with chemical alteration of the surface - haze fallout would take hundreds to tens of thousands of years to recover an altered surface. Instead the deposition and removal of a volatile layer is more consistent with the observed evolution. Different scenarios for the production and removal of such a layer are possible. We will discuss these scenarios, which include evaporative cooled frost that later sublimates, and dissolution and reprecipitation of surface organics that may later be eroded by wind.

  8. Cassini-VIMS at Jupiter: Solar occultation measurements using Io

    USGS Publications Warehouse

    Formisano, V.; D'Aversa, E.; Bellucci, G.; Baines, K.H.; Bibring, J.-P.; Brown, R.H.; Buratti, B.J.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.; Chamberlain, M.C.; Hansen, G.; Hibbits, K.; Showalter, M.; Filacchione, G.

    2003-01-01

    We report unusual and somewhat unexpected observations of the jovian satellite Io, showing strong methane absorption bands. These observations were made by the Cassini VIMS experiment during the Jupiter flyby of December/January 2000/2001. The explanation is straightforward: Entering or exiting from Jupiter's shadow during an eclipse, Io is illuminated by solar light which has transited the atmosphere of Jupiter. This light, therefore becomes imprinted with the spectral signature of Jupiter's upper atmosphere, which includes strong atmospheric methane absorption bands. Intercepting solar light refracted by the jovian atmosphere, Io essentially becomes a "miffor" for solar occultation events of Jupiter. The thickness of the layer where refracted solar light is observed is so large (more than 3000 km at Io's orbit), that we can foresee a nearly continuous multi-year period of similar events at Saturn, utilizing the large and bright ring system. During Cassini's 4-year nominal mission, this probing tecnique should reveal information of Saturn's atmosphere over a large range of southern latitudes and times. ?? 2003 Elsevier Inc. All rights reserved.

  9. Cassini-VIMS observations of Saturn's main rings: I. Spectral properties and temperature radial profiles variability with phase angle and elevation

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Ciarniello, M.; Capaccioni, F.; Clark, R. N.; Nicholson, P. D.; Hedman, M. M.; Cuzzi, J. N.; Cruikshank, D. P.; Dalle Ore, C. M.; Brown, R. H.; Cerroni, P.; Altobelli, N.; Spilker, L. J.

    2014-10-01

    The spectral properties and thermal behavior of Saturn's rings are determined from a dataset of ten radial mosaics acquired by Cassini-VIMS (Visual and Infrared Mapping Spectrometer) between October 29th 2004 and January 27th 2010 with phase angle ranging between 5.7° and 132.4° and elevation angles between -23.5° and 2.6°. These observations, after reduction to spectrograms, e.g. 2D arrays containing the VIS-IR (0.35-5.1 μm) spectral information versus radial distance from Saturn (from 73.500 to 141.375 km, 400 km/bin), allow us to compare the derived spectral and thermal properties of the ring particles on a common reference. Spectral properties: rings spectra are characterized by an intense reddening at visible wavelengths while they maintain a strong similarity with water ice in the infrared domain. Significant changes in VIS reddening, water ice abundance and grain sizes are observed across different radial regions resulting in correlation with optical depth and local structures. The availability of observations taken at very different phase angles allows us to examine spectrophotometric properties of the ring's particles. When observed at high phase angles, a remarkable increase of visible reddening and water ice band depths is found, probably as a consequence of the presence of a red-colored contaminant intimately mixed within water ice grains and of multiple scattering. At low phases the analysis of the 3.2-3.6 μm range shows faint spectral signatures at 3.42-3.52 μm which are compatible with the CH2 aliphatic stretch. The 3.29 μm PAH aromatic stretch absorption is not clearly detectable on this dataset. VIMS results indicate that ring particles contain about 90-95% water ice while the remaining 5-10% is consistent with different contaminants like amorphous carbon or tholins. However, we cannot exclude the presence of nanophase iron or hematite produced by iron oxidation in the rings tenuous oxygen atmosphere, intimately mixed with the ice grains

  10. Fuel Rod Thermal-Mechanical Behavior, Versions FRAPCON2, FRAPCON2/VIM4 & FRAPCON2/VIM5.

    2002-03-25

    Version 02 This package contains three versions of the FRAPCON series of fuel rod response modeling programs. The FRAPCON series, like the earlier FRAP-S and GAPCON-THERMAL codes, is designed to predict the steady-state long-term burnup response of oxide fuel rods in light water reactors (LWRs). In addition, these codes generate the initial conditions for transient fuel rod analysis by the FRAP-T6 or thermal-hydraulic analysis programs. The FRAPCON2 programs calculate the temperature, pressure, deformation, and failuremore » histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include heat conduction through the fuel and cladding, cladding elastic and plastic deformation, fuel-cladding mechanical interaction, fission gas release, fuel rod internal gas pressure, heat transfer between fuel and cladding, cladding oxidation, and heat transfer from cladding to coolant. Material properties, water properties, and heat transfer correlation data are included. The FRAPCON series replaced the FRAP-S1, FRAP-S2, and FRAP-S3 series of programs. The fuel temperature computation used in the FRAPCON series was taken from the GAPCON-THERMAL2 code (NESC 618). FRAPCON2/VIM4 generates the initial conditions for transient fuel rod analysis used either by FRAP-T6 (NESC 658) or RELAP4/MOD7 (NESC 369).« less

  11. Molecular epidemiology of VIM-1 producing Escherichia coli from Germany referred to the National Reference Laboratory.

    PubMed

    Kaase, Martin; Pfennigwerth, Niels; Lange, Felix; Anders, Agnes; Gatermann, Sören G

    2015-10-01

    The distribution of carbapenemase genes in Escherichia coli strains isolated between September 2009 and May 2013 in Germany was investigated. Out of 192 isolates with carbapenemase production OXA-48 was found in 44.8%, VIM-1 in 18.8%, NDM-1 in 11.5% and KPC-2 in 6.8%. Patients with VIM-1 producing E. coli (n=36) differed from patients with OXA-48 by an older age, less frequent mention of travel history and an increased proportion of clinical over screening specimens. These data might indicate that introduction from abroad is of minor importance for VIM-1 producing E. coli compared to other carbapenemases. Multilocus sequence typing revealed that E. coli with VIM-1 were mostly multiclonal, emphasizing the role of horizontal gene transfer in its spread. Susceptibility testing of VIM-1 producing E. coli demonstrated aztreonam susceptibility in 55.6%. Among non-β-lactams susceptibility rates of >90% were observed for amikacin, tigecycline, colistin, fosfomycin and nitrofurantoin.

  12. Comparison between Dione' and Helene' surfaces using Cassini VIMS

    NASA Astrophysics Data System (ADS)

    Scipioni, F.; Tosi, F.; Capaccioni, F.; Cerroni, P.; Filacchione, G.; Federico, C.

    2012-04-01

    With 1122 km in diameter, Dione is the second largest inner moon of Saturn. The Voyager spacecrafts observed Dione in 1980 and revealed a complex surface structure. Afterwards, Dione was closely observed by the Cassini-Huygens spacecraft from 2004 to 2011. Dione's surface is composed primarily by water ice with minor abundances of volatiles such as CO2 and CN. The satellite's surface can be divided into some distinct classes: most notably, heavily cratered terrains and less cratered plains. Most of Dione's surface is covered by the heavily cratered terrains, located mainly in the trailing hemisphere and crossed by high-albedo wispy streaks. The origin of the dark material that covers the heavily cratered terrains is still unknown, while wispy units are likely tectonic features. Helene is a Dione's trojan moonlet, which orbits around Saturn in Dione's lagrangian point L4. The Visual and Infrared Mapping Spectrometer (VIMS) instrument onboard the Cassini Orbiter is able to acquire hyperspectral cubes in the overall spectral range from 0.35 to 5.1 μm. We have selected 76 VIMS cubes of Dione in the IR range between 0.85 and 5.1 μm. These data show at the same time a spatial resolution better than 100 km and a good S/N ratio. We have normalized all of the spectra at λ=2.23 μm in order to minimize photometric effects due to different observation conditions. To emphasize the existence of spectral units, we have applied the supervised clustering technique Spectral Angle Mapper (SAM) to the infrared spectra of each cube. A classification method applied to hyperspectral data shows up to be crucial to understand geochemical processes taking place on the icy satellites' surfaces, and, in this particular case, to investigate the possible presence on the surface of Dione of non water-ice materials, such as methane and ammonia. Some classes show also a peculiar trend with respect to the phase angle, possibly related to surface structure. Moreover, the use of this technique

  13. The geology of Hotei Regio, Titan: Correlation of Cassini VIMS and RADAR

    USGS Publications Warehouse

    Soderblom, L.A.; Brown, R.H.; Soderblom, J.M.; Barnes, J.W.; Kirk, R.L.; Sotin, C.; Jaumann, R.; MacKinnon, D.J.; Mackowski, D.W.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    Joint Cassini VIMS and RADAR SAR data of ???700-km-wide Hotei Regio reveal a rich collection of geological features that correlate between the two sets of images. The degree of correlation is greater than anywhere else seen on Titan. Central to Hotei Regio is a basin filled with cryovolcanic flows that are anomalously bright in VIMS data (in particular at 5 ??m) and quite variable in roughness in SAR. The edges of the flows are dark in SAR data and appear to overrun a VIMS-bright substrate. SAR-stereo topography shows the flows to be viscous, 100-200 m thick. On its southern edge the basin is ringed by higher (???1 km) mountainous terrain. The mountains show mixed texture in SAR data: some regions are extremely rough, exhibit low and spectrally neutral albedo in VIMS data and may be partly coated with darker hydrocarbons. Around the southern margin of Hotei Regio, the SAR image shows several large, dendritic, radar-bright channels that flow down from the mountainous terrain and terminate in dark blue patches, seen in VIMS images, whose infrared color is consistent with enrichment in water ice. The patches are in depressions that we interpret to be filled with fluvial deposits eroded and transported by liquid methane in the channels. In the VIMS images the dark blue patches are encased in a latticework of lighter bands that we suggest to demark a set of circumferential and radial fault systems bounding structural depressions. Conceivably the circular features are tectonic structures that are remnant from an ancient impact structure. We suggest that impact-generated structures may have simply served as zones of weakness; no direct causal connection, such as impact-induced volcanism, is implied. We also speculate that two large dark features lying on the northern margin of Hotei Regio could be calderas. In summary the preservation of such a broad suite of VIMS infrared color variations and the detailed correlation with features in the SAR image and SAR topography

  14. Surface albedo changes with time on Titan's possible cryovolcanic sites: Cassini/VIMS processing and geophysical implications

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Coustenis, A.; Hirtzig, M.; Bratsolis, E.; Drossart, P.; Bampasidis, G.; Kyriakopoulos, K.; Le Mouélic, S.; Rodriguez, S.; Stephan, K.; Jaumann, R.; Sohl, F.; Wagner, F. W.; Hussmann, H.; Lopes, R. M. C.; Sotin, C.; Brown, R. H.; Stamatelopoulou-Seymour, K.; Moussas, X.

    2013-09-01

    We present a study on Titan's possibly cryovolcanic and varying regions as suggested from previous studies [e.g. 1;2;7]. These regions, which are potentially subject to change over time in brightness and are located close to the equator, are Tui Regio, Hotei Regio, and Sotra Patera. We apply two methods on Cassini/VIMS data in order to retrieve their surface properties and monitor any temporal variations. First, we apply a statistical method, the Principal Component Analysis (PCA) [3;4] where we manage to isolate regions of distinct and diverse chemical composition called 'Region of interest - RoI'. Then, we focus on retrieving the spectral differences (with respect to the Huygens landing site albedo) among the RoIs by applying a radiative transfer code (RT) [5;3]. Hence, we are able to view the dynamical range and evaluate the differences in surface albedo within the RoIs of the three regions. In addition, using this double procedure, we study the temporal surface variations of the three regions witnessing albedo changes with time for Tui Regio from 2005-2009 (darkening) and Sotra Patera from 2005-2006 (brightening) at all wavelengths [3]. The surface albedo variations and the presence of volcanic-like features within the regions in addition to a recent study [6] that calculates Titan's tidal response are significant indications for the connection of the interior with the cryovolcanic candidate features with implications for the satellite's astrobiological potential.

  15. A Mid-latitude Cloud Eruption on Titan Observed by the Cassini Visual Infrared Mapping Spectrometer (VIMS) in July 2007

    NASA Astrophysics Data System (ADS)

    Buratti, B. J.; Pitman, K. M.; Baines, K.; Sotin, C.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.; Griffith, C. A.; Le Mouelic, S.; Momary, T.

    2007-12-01

    Mid-latitude clouds on Titan have been monitored by the Cassini spacecraft since they were reported by ground- based observers (Roe et al. 2005, Ap. J. 618, L49). The Cassini Visual Infrared Mapping Spectrometer (VIMS) is especially suited to detecting and mapping these clouds because its wavelength range of 0.4-5.1 microns covers several key methane cloud filters. These clouds may be the result of atmospheric upwelling on Titan (Griffith et al. 2000 Science 290, p. 509; Rannou et al. 2006 Science 311, p. 201), or they may start as plumes coming from active geologic features on Titan (Roe et al. 2005, Science 310, p. 477). Mid-latitude clouds were observed in the early part of the nominal mission (Dec. 2004 and early 2005), but they had disappeared until a large cloud system was observed in summer 2006, in the 0-90 degrees W longitude mid-latitude regions of Titan. A new group of clouds was observed during the two flybys of July 2007, which dwarfs the previous mid-latitude system. These clouds originate in a region centered on ~200 W longitude and ~48 S latitude. Monitoring of mid-latitude clouds will show whether their timescales for formation are compatible with climate models for Titan's atmosphere. If mid-latitude clouds are the result of active geologic processes, there appears to be more than one source on Titan's surface. Work funded by NASA.

  16. Temporal Variations of Titan’s Surface Regions with Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, A.; Hirtzig, M.; Rodriguez, S.; Stephan, K.; Le Mouélic, S.; Drossart, P.; Bratsolis, E.; Jaumann, R.; Lopes, R. M.; Kyriakopoulos, K.; Sotin, C.; Brown, R. H.

    2013-10-01

    We investigate three potentially “active” areas on Titan [e.g. 1;2;7]., i.e. locations subject to change over time (in brightness and/or in color etc.), namely Tui Regio, Hotei Regio and Sotra Patera. We apply two methods on Cassini/VIMS data in order to retrieve their surface properties and monitor temporal variations. First, we apply the Principal Component Analysis (PCA) statistical method [3;4], isolating regions of distinct and diverse chemical composition (Region of interest -RoI). Then, we focus on retrieving the spectral differences (with respect to the Huygens landing site albedo) among the RoIs by applying a radiative transfer code (RT) [5;3]. We are thus able to evaluate the dynamical range and the differences in surface albedo among the RoIs of the three areas. In addition, using this double procedure, we study the temporal surface variations of the same areas. Hotei Regio has been previously suggested to present brightness variations over a two-year period (2004-2005) [3]. However, we find that to-date available observations of that area have issues (e.g. geometry conditions), which prevent an accurate application of our plane-parallel RT code. The surface information we infer for Hotei Regio does not show variations from 2004-2009 but the uncertainties here are high [8]. On the other hand, our findings indicate a significant darkening for Tui Regio from 2005-2009 (at all wavelengths). For Sotra Patera a brightening is observed from 2005-2006 [8], while test cases from two distinct dunes fields for the same period of time show that their surface albedo does not change with time. We will discuss the relation of these surface variations with the presence of volcanic-like features [7] within these areas and interior processes (tidal forces) [6] and the implications for the satellite’s astrobiological potential. [1] Soderblom, L.A. et al.: Icarus 204, 610-618, 2009. [2] Nelson, R. et al.: Icarus 199, 429-441, 2009. [3] Solomonidou, A., et al

  17. Biochemical, Mechanistic, and Spectroscopic Characterization of Metallo-β-lactamase VIM-2

    PubMed Central

    2015-01-01

    This study examines metal binding to metallo-β-lactamase VIM-2, demonstrating the first successful preparation of a Co(II)-substituted VIM-2 analogue. Spectroscopic studies of the half- and fully metal loaded enzymes show that both Zn(II) and Co(II) bind cooperatively, where the major species present, regardless of stoichiometry, are apo- and di-Zn (or di-Co) enzymes. We determined the di-Zn VIM-2 structure to a resolution of 1.55 Å, and this structure supports results from spectroscopic studies. Kinetics, both steady-state and pre-steady-state, show that VIM-2 utilizes a mechanism that proceeds through a very short-lived anionic intermediate when chromacef is used as the substrate. Comparison with other B1 enzymes shows that those that bind Zn(II) cooperatively are better poised to protonate the intermediate on its formation, compared to those that bind Zn(II) non-cooperatively, which uniformly build up substantial amounts of the intermediate. PMID:25356958

  18. Audiovisual Aids and Publications Available from the VIMS/Sea Grant Marine Education Center.

    ERIC Educational Resources Information Center

    Gammisch, Sue, Comp.

    This catalog contains an inventory of 16mm films, filmstrips, film loops, slide programs, records, and publications about the marine sciences and sea life that are available from VIMS/Sea Grant Marine Education Center; information on the borrowing of the AV materials is included, as well as prices for books and leaflets. The entries are listed…

  19. Biochemical, Mechanistic, and Spectroscopic Characterization of Metallo-β-lactamase VIM-2

    SciTech Connect

    Aitha, Mahesh; Marts, Amy R.; Bergstrom, Alex; Møller, Abraham Jon; Moritz, Lindsay; Turner, Lucien; Nix, Jay C.; Bonomo, Robert A.; Page, Richard C.; Tierney, David L.; Crowder, Michael W.

    2014-11-25

    Our study examines metal binding to metallo-β-lactamase VIM-2, demonstrating the first successful preparation of a Co(II)-substituted VIM-2 analogue. Spectroscopic studies of the half- and fully metal loaded enzymes show that both Zn(II) and Co(II) bind cooperatively, where the major species present, regardless of stoichiometry, are apo- and di-Zn (or di-Co) enzymes. We also determined the di-Zn VIM-2 structure to a resolution of 1.55 Å, and this structure supports results from spectroscopic studies. Kinetics, both steady-state and pre-steady-state, show that VIM-2 utilizes a mechanism that proceeds through a very short-lived anionic intermediate when chromacef is used as the substrate. Comparison with other B1 enzymes shows that those that bind Zn(II) cooperatively are better poised to protonate the intermediate on its formation, compared to those that bind Zn(II) non-cooperatively, which uniformly build up substantial amounts of the intermediate.

  20. First report of the blaVIM gene in environmental isolates of Buttiauxella sp.

    PubMed

    Pitondo-Silva, André; Martins, Vinicius Vicente; Stehling, Eliana Guedes

    2015-04-01

    Several works have demonstrated the presence of metallo-β-lactamases (MBLs) in clinical bacteria. However, in environmental isolates, few works have reported on these enzymes. In this study, we report for the first time two environmental isolates of Buttiauxella sp. recovered from chrysanthemum plantations in Brazil containing blaVIM gene and producing MBLs.

  1. High-resolution CASSINI-VIMS mosaics of Titan and the icy Saturnian satellites

    USGS Publications Warehouse

    Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; McCord, T.B.; Coradini, A.; Capaccioni, F.; Filacchione, G.; Cerroni, P.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Combes, M.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Langevin, Y.; Matson, D.L.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.; Soderbloom, L.A.; Griffith, C.; Matz, K.-D.; Roatsch, Th.; Scholten, F.; Porco, C.C.

    2006-01-01

    The Visual Infrared Mapping Spectrometer (VIMS) onboard the CASSINI spacecraft obtained new spectral data of the icy satellites of Saturn after its arrival at Saturn in June 2004. VIMS operates in a spectral range from 0.35 to 5.2 ??m, generating image cubes in which each pixel represents a spectrum consisting of 352 contiguous wavebands. As an imaging spectrometer VIMS combines the characteristics of both a spectrometer and an imaging instrument. This makes it possible to analyze the spectrum of each pixel separately and to map the spectral characteristics spatially, which is important to study the relationships between spectral information and geological and geomorphologic surface features. The spatial analysis of the spectral data requires the determination of the exact geographic position of each pixel on the specific surface and that all 352 spectral elements of each pixel show the same region of the target. We developed a method to reproject each pixel geometrically and to convert the spectral data into map projected image cubes. This method can also be applied to mosaic different VIMS observations. Based on these mosaics, maps of the spectral properties for each Saturnian satellite can be derived and attributed to geographic positions as well as to geological and geomorphologic surface features. These map-projected mosaics are the basis for all further investigations. ?? 2006 Elsevier Ltd. All rights reserved.

  2. Epidemiology of VIM-1-imipenem resistant Pseudomonas aeruginosa in Iran: A systematic review and meta-analysis

    PubMed Central

    Sedighi, Mansour; Salehi-Abargouei, Amin; Oryan, Golfam; Faghri, Jamshid

    2014-01-01

    Background: Pseudomonas aeruginosa is an opportunistic human pathogen which causes serious problems, especially in people who have immunodeficiency. Metallo beta-lactamase (MBL) resistance in this bacterium has led some difficulties in treating bacterial infections. MBLs are being reported with increasing frequency worldwide. The aim of the present systematic review and meta-analysis was to collect data about the relative frequency (RF) of VIM-1-imipenem resistant P. aeruginosa (VIM-1-IRPA) in different regions of Iran and report an overall prevalence if possible. Materials and Methods: PubMed, ISI web of science, Scopus and Google Scholar were searched using following key terms: “P. aeruginosa,” “imipenem,” “VIM-1” and “Iran” were. Articles/abstracts, which used clinical specimens and had done polymerase chain reaction to detect the VIM-1 gene of MBL genes, were included in this review. STATA SE version 11.2 (StataCorp, College Station, TX, USA) was used for statistical analysis. Results: Out of 5457 results found, 10 articles were eligible to be included in our systematic review and meta-analysis. These studies were carried out in Tehran, Isfahan, Kurdistan, Ahvaz, Markazi and Northwest of Iran (Orumieh and Tabriz). Pooled estimation of 1972 P. aeruginosa samples showed that 13% (95% confidence interval = 10.5-16.5%]) of strains were VIM-1 positive. VIM-1-IRPA RF in different studies varied from 0% to 19.5% in Isfahan and Markazi provinces, respectively. We found a moderate heterogeneity (Chochran Q-test, P = 0.032, I-squared = 50.7%) of VIM-1-IRPA RF among studies. Conclusion: According to the results of this study VIM-1-IRPA RF in Iran is in low-level Prevention strategies to reduce the prevalence rates of VIM-1 positive strains in Iran are needed. PMID:25535506

  3. Fast forward modeling of Titan’s infrared spectra to invert VIMS/CASSINI hyperspectral images

    NASA Astrophysics Data System (ADS)

    Rodriguez, S.; Le Mouélic, S.; Rannou, P.; Combe, J.; Le Corre, L.; Griffith, C. A.; Tobie, G.; Barnes, J. W.; Sotin, C.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.

    2009-12-01

    The surface of Titan, the largest icy moon of Saturn, is veiled by a very thick and hazy atmosphere. The Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft, in orbit around Saturn since July 2004, has been conducting an intensive survey of Titan with the objective of understanding the complex nature and interaction of the atmosphere and surface of this mysterious moon. Retrieving and separating contributions from the surface and the atmosphere in Titan’s infrared spectra requires accurate radiative transfer modeling, which is often very demanding of computer resources. As Cassini has gathered hitherto millions of spectra of Titan and will continue to observe it until at least 2010, we report here on the development of a new rapid, simple and versatile radiative transfer model specially designed to process VIMS datacubes. Currently, our model accounts for gas absorption, haze scattering and surface reflectance and can be implemented in an inversion scheme. First results of forward modeling provide spectral shapes that are consistent with VIMS measurements, as well as surface and aerosol properties in the range of validity for Titan. Further inversion tests will be carried on VIMS hyperspectral images for the estimate of spatial coherence of the results, accuracy of the surface reflectance within the atmospheric windows, and potential needs for improved input data and modeling. This work was partly performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration. Calibrated VIMS data appear courtesy of the VIMS team. We thank the CNES French agency for its financial support.

  4. Multi-wavelength high-resolution observations of a small-scale emerging magnetic flux event and the chromospheric and coronal response

    SciTech Connect

    Vargas Domínguez, Santiago; Kosovichev, Alexander; Yurchyshyn, Vasyl

    2014-10-20

    State-of-the-art solar instrumentation is now revealing magnetic activity of the Sun with unprecedented temporal and spatial resolutions. Observations with the 1.6 m aperture New Solar Telescope (NST) of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence and the response of the solar atmosphere are among the key research topics of high-resolution solar physics. As part of a joint observing program with NASA's Interface Region Imaging Spectrograph (IRIS) mission on 2013 August 7, the NST observed active region NOAA 11,810 in the photospheric TiO 7057 Å band with a resolution of pixel size of 0.''034 and chromospheric He I 10830 Å and Hα 6563 Å wavelengths. Complementary data are provided by the Solar Dynamics Observatory (SDO) and Hinode space-based telescopes. The region displayed a group of solar pores, in the vicinity of which we detect a small-scale buoyant horizontal magnetic flux tube causing granular alignments and interacting with the preexisting ambient field in the upper atmospheric layers. Following the expansion of distorted granules at the emergence site, we observed a sudden appearance of an extended surge in the He I 10830 Å data (bandpass of 0.05 Å). The IRIS transition region imaging caught ejection of a hot plasma jet associated with the He I surge. The SDO/HMI data used to study the evolution of the magnetic and Doppler velocity fields reveal emerging magnetic loop-like structures. Hinode/Ca II H and IRIS filtergrams detail the connectivities of the newly emerged magnetic field in the lower solar chromosphere. From these data, we find that the orientation of the emerging magnetic field lines from a twisted flux tube formed an angle of ∼45° with the overlying ambient field. Nevertheless, the interaction of emerging magnetic field lines with the pre-existing overlying field generates high-temperature emission regions and boosts the surge

  5. Multi-wavelength High-resolution Observations of a Small-scale Emerging Magnetic Flux Event and the Chromospheric and Coronal Response

    NASA Astrophysics Data System (ADS)

    Vargas Domínguez, Santiago; Kosovichev, Alexander; Yurchyshyn, Vasyl

    2014-10-01

    State-of-the-art solar instrumentation is now revealing magnetic activity of the Sun with unprecedented temporal and spatial resolutions. Observations with the 1.6 m aperture New Solar Telescope (NST) of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence and the response of the solar atmosphere are among the key research topics of high-resolution solar physics. As part of a joint observing program with NASA's Interface Region Imaging Spectrograph (IRIS) mission on 2013 August 7, the NST observed active region NOAA 11,810 in the photospheric TiO 7057 Å band with a resolution of pixel size of 0.''034 and chromospheric He I 10830 Å and Hα 6563 Å wavelengths. Complementary data are provided by the Solar Dynamics Observatory (SDO) and Hinode space-based telescopes. The region displayed a group of solar pores, in the vicinity of which we detect a small-scale buoyant horizontal magnetic flux tube causing granular alignments and interacting with the preexisting ambient field in the upper atmospheric layers. Following the expansion of distorted granules at the emergence site, we observed a sudden appearance of an extended surge in the He I 10830 Å data (bandpass of 0.05 Å). The IRIS transition region imaging caught ejection of a hot plasma jet associated with the He I surge. The SDO/HMI data used to study the evolution of the magnetic and Doppler velocity fields reveal emerging magnetic loop-like structures. Hinode/Ca II H and IRIS filtergrams detail the connectivities of the newly emerged magnetic field in the lower solar chromosphere. From these data, we find that the orientation of the emerging magnetic field lines from a twisted flux tube formed an angle of ~45° with the overlying ambient field. Nevertheless, the interaction of emerging magnetic field lines with the pre-existing overlying field generates high-temperature emission regions and boosts the surge

  6. Aromatic and aliphatic organic materials on Iapetus: Analysis of Cassini VIMS data

    NASA Astrophysics Data System (ADS)

    Cruikshank, Dale P.; Dalle Ore, Cristina M.; Clark, Roger N.; Pendleton, Yvonne J.

    2014-05-01

    , D.P., Clark, R.N. [2012], op. cit.) and Phoebe (Dalle Ore, C.M., Cruikshank, D.P., Clark, R.N. [2012], op. cit.). Our Gaussian decomposition of the organic band region suggests the presence of molecular bands in addition to those noted above, specifically bands attributable to cycloalkanes, olefinic compounds, CH3OH, and N-substituted PAHs, as well as possible Hn-PAHs (PAHs with excess peripheral H atoms). In a minimalist interpretation of the Gaussian band fitting, we find the ratio of aromatic CH to aliphatic CH2 + CH3 functional groups for both the leading and trailing hemispheres of Iapetus is ∼10, with no clear difference between them. In the aliphatic component of the surface material, the ratio CH2/CH3 is 4.0 on the leading hemisphere and 3.0 on the trailing; both values are higher than those found in interstellar dust and other Solar System materials and the difference between the two hemispheres may be statistically significant. The superficial layer of low-albedo material on Iapetus originated in the interior of Phoebe and is being transported to and deposited on Iapetus (and Hyperion) in the current epoch via the Phoebe dust ring (Tosi, F., Turrini, D., Coradini, A., Filacchione, G., and the VIMS Team [2010]. Mon. Not. R. Astron. Soc. 403, 1113-1130; Tamayo, D., Burns, J.A., Hamilton, D.P., Hedman, M.M. [2011]. Icarus 215, 260-278). The PAHs on Iapetus exist in a H2O-rich environment, and consequently are subject to UV destruction by hydrogenation on short time-scales. The occurrence of this material is therefore consistent with the assertion that the deposition of the PAH-bearing dust is occurring at the present time. If the organic inventory we observe represents the interior composition of Phoebe, we may be sampling the original material from a region of the solar nebula beyond Neptune where Phoebe formed prior to its capture by Saturn (Johnson, T.V., Lunine, J.I. [2005]. Nature 435, 69-71).

  7. A color sensor wavelength meter

    NASA Astrophysics Data System (ADS)

    Durfee, Dallin; Jackson, Jarom; Otterstrom, Nils; Jones, Tyler; Archibald, James

    2016-05-01

    We will discuss a laser wavelength meter based on a commercial color sensor chip consisting of an array of photodiodes with different absorptive color filters. By comparing the relative amplitudes of light on the photodiodes, the wavelength of light can be determined with picometer-level precision and with picometer-scale calibration drift over a period longer than a month. This work was supported by NSF Grant Number PHY-1205736.

  8. Saturn's icy satellites investigated by Cassini-VIMS. I. Full-disk properties: 350-5100 nm reflectance spectra and phase curves

    USGS Publications Warehouse

    Filacchione, G.; Capaccioni, F.; McCord, T.B.; Coradini, A.; Cerroni, P.; Bellucci, G.; Tosi, F.; D'Aversa, E.; Formisano, V.; Brown, R.H.; Baines, K.H.; Bibring, J.-P.; Buratti, B.J.; Clark, R.N.; Combes, M.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.; Hansen, G.; Hibbitts, K.; Showalter, M.; Newman, S.

    2007-01-01

    Saturn's icy satellites are among the main scientific objectives of the Cassini-VIMS (Visual and Infrared Mapping Spectrometer) experiment. This paper contains a first systematic and comparative analysis of the full-disk spectral properties of Dione, Enceladus, Epimetheus, Hyperion, Iapetus, Mimas, Phoebe, Rhea and Tethys as observed by VIMS from July 2004 to June 2005. The disk integrated properties (350-5100 nm reflectance spectra and phase curves at 550-2232 nm) and images of satellites are reported and discussed in detail together with the observed geometry. In general, the spectra in the visible spectral range are almost featureless and can be classified according to the spectral slopes: from the bluish Enceladus and Phoebe to the redder Iapetus, Hyperion and Epimetheus. In the 1000-1300 nm range the spectra of Enceladus, Tethys, Mimas and Rhea are characterized by a negative slope, consistent with a surface largely dominated by water ice, while the spectra of Iapetus, Hyperion and Phoebe show a considerable reddening pointing out the relevant role played by darkening materials present on the surface. In between these two classes are Dione and Epimetheus, which have a flat spectrum in this range. The main absorption bands identified in the infrared are the 1520, 2020, 3000 nm H2O/OH bands (for all satellites), although Iapetus dark terrains show mostly a deep 3000 nm band while the 1520 and 2020 nm bands are very faint. In this spectral range, the Iapetus spectrum is characterized by a strong reddening. The CO2 band at 4260 nm and the Fresnel ice peak around 3100 nm are evident only on Hyperion, Phoebe and Iapetus. The phase curves at 550 and at 2232 nm are reported for all the available observations in the 0??-144?? range; Rhea shows an opposition surge at visible wavelengths in the 0.5??-1.17?? interval. The improvement on the retrieval of the full-disk reflectance spectra can be appreciated by a direct comparison with ground-based telescopic data available

  9. Correlations between Cassini VIMS spectra and RADAR SAR images: Implications for Titan's surface composition and the character of the Huygens Probe Landing Site

    USGS Publications Warehouse

    Soderblom, L.A.; Kirk, R.L.; Lunine, J.I.; Anderson, J.A.; Baines, K.H.; Barnes, J.W.; Barrett, J.M.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Cruikshank, D.P.; Elachi, C.; Janssen, M.A.; Jaumann, R.; Karkoschka, E.; Le Mouélic, Stéphane; Lopes, R.M.; Lorenz, R.D.; McCord, T.B.; Nicholson, P.D.; Radebaugh, J.; Rizk, B.; Sotin, C.; Stofan, E.R.; Sucharski, T.L.; Tomasko, M.G.; Wall, S.D.

    2007-01-01

    Titan's vast equatorial fields of RADAR-dark longitudinal dunes seen in Cassini RADAR synthetic aperture images correlate with one of two dark surface units discriminated as "brown" and "blue" in Visible and Infrared Mapping Spectrometer (VIMS) color composites of short-wavelength infrared spectral cubes (RGB as 2.0, 1.6, 1.3 ??m). In such composites bluer materials exhibit higher reflectance at 1.3 ??m and lower at 1.6 and 2.0 ??m. The dark brown unit is highly correlated with the RADAR-dark dunes. The dark brown unit shows less evidence of water ice suggesting that the saltating grains of the dunes are largely composed of hydrocarbons and/or nitriles. In general, the bright units also show less evidence of absorption due to water ice and are inferred to consist of deposits of bright fine precipitating tholin aerosol dust. Some set of chemical/mechanical processes may be converting the bright fine-grained aerosol deposits into the dark saltating hydrocarbon and/or nitrile grains. Alternatively the dark dune materials may be derived from a different type of air aerosol photochemical product than are the bright materials. In our model, both the bright aerosol and dark hydrocarbon dune deposits mantle the VIMS dark blue water ice-rich substrate. We postulate that the bright mantles are effectively invisible (transparent) in RADAR synthetic aperture radar (SAR) images leading to lack of correlation in the RADAR images with optically bright mantling units. RADAR images mostly show only dark dunes and the water ice substrate that varies in roughness, fracturing, and porosity. If the rate of deposition of bright aerosol is 0.001-0.01 ??m/yr, the surface would be coated (to optical instruments) in hundreds-to-thousands of years unless cleansing processes are active. The dark dunes must be mobile on this very short timescale to prevent the accumulation of bright coatings. Huygens landed in a region of the VIMS bright and dark blue materials and about 30 km south of the

  10. KPC and VIM producing Enterobacter cloacae strain from a hospital in northeastern Venezuela.

    PubMed

    Martínez, Dianny; Marcano, Daniel; Rodulfo, Hectorina; Salgado, Nurys; Cuaical, Nirvia; Rodriguez, Lucy; Caña, Luisa; Medina, Belkis; Guzman, Militza; De Donato, Marcos

    2015-06-01

    An 83-year-old male patient is admitted to the central hospital in Cumana, Venezuela with severe urinary infection, history of hospitalizaions and prolonged antimicrobial treatments. A strain of Enterobacter cloacae was isolated showing resistance to multiple types of antibiotics (only sensitive to gentamicin), with phenotype of serine- and metallo-carbapenemases. Both, bla(VIM-2) and bla(KPC) genes were detected in the isolate. This is the first report of an Enterobacteriaceae species producing both KPC carbapenemase and VIM metallo carbapenemase in Venezuela. This finding has a great clinical and epidemiological impact in the region, because of the feasibility of transferring these genes, through mobile elements to other strains of Enterobacter and to other infection-causing species of bacteria.

  11. Cassini VIMS-V observations of a giant dynamical structure in the Saturn's northern hemisphere

    NASA Astrophysics Data System (ADS)

    Moriconi, M. L.; D'Aversa, E.; Adriani, A.; Filacchione, G.

    2012-12-01

    Vortices have been observed on Saturn since the years of the Voyager's missions. Successively high resolution Cassini's images, provided by the Imaging Science Subsystem (ISS) cameras, permitted longer periods of observation of the Saturn's dynamical structures, included a long-lived cyclone in the southern hemisphere (del Río-Gaztelurrutia et al., 2010). The Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini spacecraft on January 4th 2012 has observed an oval structure, about 8000 km in diameter size and 0.87 eccentricity in the Saturn's north hemisphere. The vortex is centered at an average planetocentric latitude of 37.5 °North, inside the storm system detected at the end of 2010 (Fletcher et al, 2011). To find the first occurrence of this vortex we started the examination of the VIMS and ISS databases from the 2010 fall until the end of January 2012. We searched also in the archive of ISS narrow angle (NAC) and wide angle (WAC) cameras, publicly available from the NASA Planetary Data System (PDS) Imaging Node, for those images both in concomitance and time shifted with respect to the VIMS ones. We adopted the same identification criterion used by del Río-Gaztelurrutia et al. (2010), by searching for an oval of analogous dimension in the same zonal region. ISS data helped us in checking the existence of the oval in time periods not covered by VIMS data and in resolving oval's details that we cannot appreciate in the VIMS spectral frames, less spatially resolved than the cameras' corresponding filters. This vortex has been observed at different distances and viewing geometries at least 6 and 5 times by VIMS and ISS, respectively, in the examined time period. We estimate that the first vortex's detection occurred in the first half of January 2011 (ISS) while the last one in January 2012 (VIMS). In this study we aim to determine the oval identity in a univocal way, on the basis of its position and size, in order to monitor both the structure living

  12. Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity

    NASA Astrophysics Data System (ADS)

    Hirtzig, M.; Bézard, B.; Coustenis, A.; Lellouch, E.; Drossart, P.; deBergh, C.; Campargue, A.; Boudon, V.; Tyuterev, V.; Rannou, P.; Cours, T.; Kassi, S.; Nikitin, A.; Wang, L.; Solomonidou, A.; Schmitt, B.; Rodriguez, S.

    2012-04-01

    In this paper we present an updated analysis of VIMS data in view of recent developments on the methane opacity in the 1.3-5.2 µm region, a very important parameter in simulating Titan's spectrum. We use a multi-stream radiative transfer model, benefitting from the latest methane absorption coefficients available [1], which allows us to determine more accurately the haze and surface contributions. This code is applied to Cassini/VIMS spectro-imaging data of various regions with very different spectral responses to extract information on the content of the lower atmosphere (0-200 km) as well as on the surface properties. In particular, we update the DISR aerosol model [2] for the Huygens landing site that we then adjust to fit the data for other locations on Titan's disk. Fitting VIMS data taken from 2004 to 2010 (TA to T70), around Titan's mid-latitudes (40°S-40°N), we determine the latitudinal and temporal evolution of the aerosol population, monitoring the North-South Asymmetry. While around the equinox [3] witnessed the collapse of the detached haze layer, we measure a continuous depletion of the aerosols throughout the atmosphere, although the NSA remains with a brighter northern hemisphere. Using this improved atmospheric model, we also retrieve surface albedos simultaneously for all the seven windows in the whole VIMS range for these regions, also recovering the shape of the surface albedo within each window. Eventually, we look for Titan's surface probable chemical composition, using mixtures of dark and complex hydrocarbons like bitumens and tholins, as well as bright CH4, CO2, NH3 and H2O ices of various grain sizes. [4] [1] Campargue, A. et al., (2012) Icarus, submitted. [2] Tomasko, M. et al., (2008) Planetary and Space Science, 56, 669. [3] West, R.A. et al., (2011) Geophysical Research Letters, 38, L06204. [4] Hirtzig, M. et al., (2012) Planetary and Space Science, submitted.

  13. EEG based time and frequency dynamics analysis of visually induced motion sickness (VIMS).

    PubMed

    Arsalan Naqvi, Syed Ali; Badruddin, Nasreen; Jatoi, Munsif Ali; Malik, Aamir Saeed; Hazabbah, Wan; Abdullah, Baharudin

    2015-12-01

    3D movies are attracting the viewers as they can see the objects flying out of the screen. However, many viewers have reported various problems which are usually faced after watching 3D movies. These problems include visual fatigue, eye strain, headaches, dizziness, blurred vision or collectively may be termed as visually induced motion sickness (VIMS). This research focuses on the comparison between 3D passive technology with a conventional 2D technology to find that whether 3D is causing trouble in the viewers or not. For this purpose, an experiment was designed in which participants were randomly assigned to watch 2D or a 3D movie. The movie was specially designed to induce VIMS. The movie was shown for the duration of 10 min to every participant. The electroencephalogram (EEG) data was recorded throughout the session. At the end of the session, participants rated their feelings using simulator sickness questionnaire (SSQ). The SSQ data was analyzed and the ratings of 2D and 3D participants were compared statistically by using a two tailed t test. From the SSQ results, it was found that participants watching 3D movies reported significantly higher symptoms of VIMS (p value <0.05). EEG data was analyzed by using MATLAB and topographic plots are created from the data. A significant difference has been observed in the frontal-theta power which increases with the passage of time in 2D condition while decreases with time in 3D condition. Also, a decrease in beta power has been found in the temporal lobe of 3D group. Therefore, it is concluded that there are negative effects of 3D movies causing significant changes in the brain activity in terms of band powers. This condition leads to produce symptoms of VIMS in the viewers. PMID:26462677

  14. Emergence of VIM-1-carbapenemase-producing Enterobacter cloacae in Tyrol, Austria.

    PubMed

    Heller, Ingrid; Grif, Katharina; Orth, Dorothea

    2012-04-01

    The rapid emergence and dissemination of carbapenemase-producing Enterobacter species and other members of the Enterobacteriaceae poses a considerable threat to the care of hospitalized patients and to public health. In this study, Enterobacter isolates demonstrating decreased susceptibility to carbapenems detected at the Division of Hygiene and Medical Microbiology, Innsbruck Medical University, between January 2006 and December 2010 were tested for bla(VIM-1), bla(NDM-1), bla(IMP), bla(KPC) and bla(OXA-48) using a multiplex PCR with published primers. PFGE was performed to determine the genetic relatedness. In total, 33 isolates (28 Enterobacter cloacae and 5 Enterobacter aerogenes) were collected during the study period. From 2006 to 2009, between two and seven isolates were found per year. In 2010, a significant increase of carbapenem-resistant strains was observed (n = 12). The bla(VIM-1) gene was detected in all 28 isolates of E. cloacae. Typing of E. cloacae by PFGE revealed three distinct clusters, the biggest of which contained 18 isolates. These findings demonstrate the emergence of VIM-1-producing Enterobacter in Tyrol, western Austria. The clonal relationship confirms the risk of spread of these organisms and their possible persistence over time.

  15. Studies of Saturn's Main Rings at Multiple Wavelengths

    NASA Astrophysics Data System (ADS)

    Spilker, L. J.; Deau, E.; Filacchione, G.; Morishima, R.; Hedman, M. M.; Nicholson, P. D.; Colwell, J. E.; Bradley, E. T.; Showalter, M.; Pilorz, S.; Brooks, S. M.

    2015-12-01

    A wealth of information about the characteristics of Saturn's ring particles and their regolith can be obtained by modeling the changes in their brightness, color and temperature with changing viewing geometry over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly studied using data from the lit and unlit main rings at multiple geometries and solar elevations over 11 years of the Cassini mission. Using multi-wavelength data sets allow us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation. The CIRS temperature and ISS color variations are confined primarily to phase angle over a range of solar elevations with only small differences from changing spacecraft elevation. Color and temperature dependence with varying solar elevation angle are also observed. Brightness dependence with changing solar elevation angle and phase angle is observed with UVIS. VIMS observations show that the IR ice absorption band depths are a very weak function of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces of the clumps, as well as a contribution from scattering between individual particles in a many-particle-thick layer. Preliminary results from our joint studies will be presented. This research was carried out in part at

  16. High resolution VIMS images of Titan's surface: implications for its composition, internal structure and dynamics

    NASA Astrophysics Data System (ADS)

    Sotin, C.; Le Mouelic, S.; Le Corre, L.; Barnes, J.; Brown, R. H.; Jaumann, R.; Buratti, B.; Baines, K.; Clark, R.; Nicholson, P.; Soderblom, L.

    2008-12-01

    With a field of view of 0.5 mrad per pixel, the VIMS (Visual and Infrared Mapping Spectrometer) onboard the Cassini spacecraft can acquire images with a resolution of 500 m per pixel at closest approach during a typical Titan flyby. This resolution is comparable to the resolution of the radar instrument and allows comparisons between the radar images and optical images in the six infrared windows where the surface can be observed. Such opportunities were not set up for the nominal tour before Saturn insertion. The opportunity was offered during the TA flyby [Sotin et al., Nature, 2005] and the results lead the Cassini program to give VIMS the prime observations during closest approach at the T24 and T38 flybys. Two different implementations were experienced. During the T24 flyby (01/29/2007), we used a push-broom mode allowing VIMS to image a long path before pointing to a specific site at the limit between the light and dark terrains. This observation allowed us to see the dunes and to infer some information on their composition [Barnes et al., Icarus, 2008], to image channels and to infer information of erosion processes of the bright equatorial regions [Jaumann et al., Icarus, in press] and to observe the strong correlation between radar images and the VIMS images over a bright area interpreted as a flow feature [Lopes et al., Icarus, 2007]. During the T38 flyby over Ontario Lacus (12/05/2007), it was decided to point to the lake and get different images which provide us with a set of observations obtained with different emergence angles. This observation allowed us to infer the liquid nature of the lake and the composition of the lake [Brown et al., Nature, 2008]. In addition, this mode gives good information on the atmospheric component and will help us remove that component to get better spectra of Titan's surface. During the extended mission, two observations are forecasted at the beginning and at the end of the Cassini Equinox Mission. The first one will

  17. The two-micron spectral characteristics of the Titanian haze derived from Cassini/VIMS solar occultation spectra

    NASA Astrophysics Data System (ADS)

    Sim, Chae Kyung; Kim, Sang Joon; Courtin, Régis; Sohn, Mirim; Lee, Dong-Hun

    2013-11-01

    Vertically-resolved spectral characteristics of the Titanian haze in the 2-μm wavelength range were derived from solar occultation spectra measured by Cassini/VIMS on January 15, 2006. At the various altitudes probed by the solar occultation measurements, we reproduced the observed spectra using a radiative transfer program including absorption by CH4 ro-vibrational bands, collision-induced absorption by N2-N2 pairs, and H2-N2 dimers, as well as absorption and scattering by the haze particles. The retrieved optical depth spectra (or τ-spectra) for the haze show marked variations in the 2.1-2.8 μm range, with peaks near 2.30 and 2.35 μm, and the relative amplitude of these peaks changing with altitude. The gross spectral shape of the τ-spectra is found similar to the typical 2-μm absorption spectra of the alkane group of hydrocarbon (CnH2n+2) ices. The τ-spectra retrieved at 2 μm and those previously retrieved at 3 μm by Kim et al. (2011) are simultaneously reproduced by combinations of 2- and 3-μm absorbance spectra of alkane ices such as CH4, C2H6, C5H12, C6H14, with the addition of a nitrile ice, CH3CN. These combinations are neither unique nor limited and need more fine-tuning to fit the detailed features of the τ-spectra. There is a need for additional laboratory measurements of absorbance and indices of refraction for a wider variety of hydrocarbon and nitrile ices in the temperature range relevant to Titan.

  18. The Radial Distribution Of Water Ice And Reddening Material Across Saturn's Icy Satellites And Rings Retrieved From Cassini Vims Observations

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, F.; Cerroni, P.; Clark, R. N.; Brown, R. H.; Cuzzi, J. N.; Buratti, B. J.; Coradini, A.; Tosi, F.; Ciarniello, M.; Cruikshank, D. P.; Jaumann, R.; Nicholson, P. D.; Stephan, K.; Baines, K. H.

    2010-10-01

    In the past few years we have retrieved the amount of water ice and red contaminant materials distributed across the Saturnian Icy satellites surfaces and Ring regions using Cassini-VIMS observations. These measurements highlight very striking differences among the Saturn system objects, which vary from the almost uncontaminated and water ice-rich surfaces of Enceladus and Calypso to the metal/organic-rich and red surfaces of Iapetus leading hemisphere and Phoebe. In this framework we have developed a method to compare surface composition versus radial distance from Saturn and satellites' densities. In the F ring environment, the inner minor satellites (Prometheus, Pandora, Janus and Epimetheus) have in average surface water ice abundance similar to C ring and Cassini division particles but with much less reddening contaminant. Although their orbits are close to the F-ring, Prometheus and Pandora have very striking differences in surface composition, Prometheus being very water ice-rich but at the same time very red at VIS wavelengths. These properties make it very similar to A-B ring particles while Pandora is bluer. Moving outwards, we see the effects of E ring particles generated by Enceladus plumes contaminated surfaces from Mimas up to Rhea. We found some differences between Tethys’ lagrangian moons, Calypso being much more water ice-rich and bluer with respect to Telesto. Among outer satellites (Hyperion, Iapetus and Phoebe) we observe a linear trend in both water ice decrease and in reddening, Hyperion being the reddest object of the population. This research is supported by an Italian Space Agency Grant.

  19. Saturn's icy satellites and rings investigated by Cassini-VIMS: III - Radial compositional variability

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Clark, R. N.; Cuzzi, J. N.; Nicholson, P. D.; Cruikshank, D. P.; Hedman, M. M.; Buratti, B. J.; Lunine, J. I.; Soderblom, L. A.; Tosi, F.; Cerroni, P.; Brown, R. H.; McCord, T. B.; Jaumann, R.; Stephan, K.; Baines, K. H.; Flamini, E.

    2012-08-01

    In the last few years Cassini-VIMS, the Visible and Infrared Mapping Spectrometer, returned to us a comprehensive view of the Saturn's icy satellites and rings. After having analyzed the satellites' spectral properties (Filacchione, G., Capaccioni, F., McCord, T.B., Coradini, A., Cerroni, P., Bellucci, G., Tosi, F., D'Aversa, E., Formisano, V., Brown, R.H., Baines, K.H., Bibring, J.P., Buratti, B.J., Clark, R.N., Combes, M., Cruikshank, D.P., Drossart, P., Jaumann, R., Langevin, Y., Matson, D.L., Mennella, V., Nelson, R.M., Nicholson, P.D., Sicardy, B., Sotin, C., Hansen, G., Hibbitts, K., Showalter, M., Newman, S. [2007]. Icarus 186, 259-290, paper I) and their distribution across the satellites' hemispheres (Filacchione, G., Capaccioni, F., Clark, R.N., Cuzzi, J.N., Cruikshank, D.P., Coradini, A., Cerroni, P., Nicholson, P.D., McCord, T.B., Brown, R.H., Buratti, B.J., Tosi, F., Nelson, R.M., Jaumann, R., Stephan, K. [2010]. Icarus 206, 507-523, paper II), we proceed in this paper to investigate the radial variability of icy satellites (principal and minor) and main rings average spectral properties. This analysis is done by using 2264 disk-integrated observations of the satellites and a 12 × 700 pixels-wide rings radial mosaic acquired with a spatial resolution of about 125 km/pixel. Using different VIS and IR spectral indicators, e.g. spectral slopes and band depths, we perform a comparative analysis of these data aimed to measure the distribution of water ice and red contaminant materials across Saturn's system. The average surface regolith grain sizes are estimated with different indicators through comparison with laboratory and synthetic spectra. These measurements highlight very striking differences in the population here analyzed, which vary from the almost uncontaminated and water ice-rich surfaces of Enceladus and Calypso to the metal/organic-rich and red surfaces of Iapetus' leading hemisphere and Phoebe. Rings spectra appear more red than the icy

  20. Saturn's system ices: a comparative spectral study by Cassini-VIMS

    NASA Astrophysics Data System (ADS)

    Filacchione, Gianrico; Capaccioni, Fabrizio; Clark, Roger N.; Cuzzi, Jeff N.; Cruikshank, Dale P.; Coradini, Angioletta; Cerroni, Priscilla; Tosi, Federico; Ciarniello, Mauro; Nicholson, Phil D.; McCord, Thomas B.; Brown, Robert H.; Buratti, Bonnie J.; Jaumann, Ralf; Stephan, Katrin

    2010-05-01

    The Visual and Infrared Mapping Spectrometer (VIMS) has observed the entire population of Saturnian icy objects, allowing a comparative analysis of the VIS-NIR spectral properties of the regular satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus, Phoebe), minor moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso) and main rings (A, B, C and Cassini division). The results we present are derived from the entire dataset available after about 5 years of the Cassini mission, which consists of more than 2000 full-disk observations of the moons as well as several radial mosaics of the ring system. The spectra of Saturn's satellites are characterized by a step red slope in the 0.35-0.55 µm range, which is highly diagnostic of the presence of organic contaminants and darkening agents on icy surfaces; in the 0.55-0.95 µm range the spectra become more flat and featureless. In the IR range the water ice bands at 1.5-2.0-3.0 µm bands are evident everywhere, while the CO2 ice band at 4.26 µm is seen only on the three external satellites Hyperion, Iapetus and Phoebe. Some specific spectrophotometric indicators are chosen to retrieve the macroscopic properties of the ices: I/F continuum levels, 0.35-0.55 and 0.55-0.95 µm spectral slopes, H2O-CO2 ice band depths and band positions. By using these indicators the Saturn's satellites are grouped in distinct classes, noticeably between the almost pure water ice and blue surfaces of Enceladus and Calypso to the organic- and carbon dioxide-rich Hyperion, Iapetus and Phoebe. Hyperion and the leading hemisphere of Iapetus have the reddest VIS slopes of the group. Janus' visible colors are intermediate between these two classes having a slightly positive VIS spectral slope, while Epimetheus is more neutral and similar to Iapetus' bright terrains (trailing hemisphere), Mimas and Tethys. The two F ring's shepherd moons, Prometheus and Pandora, have similarities with Atlas, while Calypso and Telesto

  1. The temperature and width of an active fissure on Enceladus measured with Cassini VIMS during the 14 April 2012 South Pole flyover

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Brown, Robert H.; Clark, Roger N.; Nicholson, Phillip D.; Hedman, Matthew M.; Howell, Robert R.; Sotin, Christophe; Cruikshank, Dale P.; Baines, Kevin H.; Lawrence, Kenneth J.; Spencer, John R.; Blackburn, David G.

    2013-09-01

    The width and temperature of the active fissures on Saturn’s satellite Enceladus provide key observable constraints on physical models of these geyser-like eruptions. We analyze a sequence of high spatial resolution near-infrared spectra acquired with VIMS at 0.025 s intervals during a 74 km altitude flyover of the South Pole of Enceladus by the Cassini spacecraft on 14 April 2012 UTC. A thermal-emission spectrum covering 3- to 5-μm wavelengths was detected as the field of view crossed one of the four major fissures, Baghdad Sulcus, within 1 km of 82.36S latitude and 28.24W longitude. We interpret this spectrum as thermal emission from a linear fissure with temperature 197 ± 20 K and width 9 m. At the above wavelengths, the spectrum is dominated by the warmest temperature component. Looking downward into the fissure at only 13° from the vertical, we conclude that our results measure the temperature of the interior fissure walls (and the H2O vapor) at depths within 40 m of the surface.

  2. Infections with VIM-1 Metallo-β-Lactamase-Producing Enterobacter cloacae and Their Correlation with Clinical Outcome▿

    PubMed Central

    Falcone, Marco; Mezzatesta, Maria Lina; Perilli, Mariagrazia; Forcella, Chiara; Giordano, Alessandra; Cafiso, Viviana; Amicosante, Gianfranco; Stefani, Stefania; Venditti, Mario

    2009-01-01

    The aim of this study was to ascertain the incidence and clinical significance of metallo-β-lactamases among Enterobacter strains isolated from patients with nosocomial infections. We prospectively collected data on patients with Enterobacter infection during a 13-month period. All of the strains were investigated for antibiotic susceptibility, the presence and expression of metallo-β-lactamases, and clonality. Of 29 infections (11 involving the urinary tract, 7 pneumonias, 3 skin/soft tissue infections, 3 intra-abdominal infections, 3 bacteremias, and 2 other infections), 7 (24%) were caused by Enterobacter cloacae strains harboring a blaVIM-1 gene associated or not with a blaSHV12 gene. Infections caused by VIM-1-producing strains were more frequently associated with a recent prior hospitalization (P = 0.006), cirrhosis (P = 0.03), relapse of infection (P < 0.001), and more prolonged duration of antibiotic therapy (P = 0.01) than were other infections. All of the isolates were susceptible to imipenem and meropenem and had blaVIM-1 preceded by a weak P1 promoter and inactivated P2 promoters. Most VIM-1-producing Enterobacter isolates belonged to a main clone, but four different clones were found. Multiclonal VIM-1-producing E. cloacae infections are difficult to diagnose due to an apparent susceptibility to various beta-lactams, including carbapenems, and are associated with a high relapse rate and a more prolonged duration of antibiotic therapy. PMID:19741074

  3. Aerosol optical depth assimilation for a size-resolved sectional model: impacts of observationally constrained, multi-wavelength and fine mode retrievals on regional scale analyses and forecasts

    NASA Astrophysics Data System (ADS)

    Saide, P. E.; Carmichael, G. R.; Liu, Z.; Schwartz, C. S.; Lin, H. C.; da Silva, A. M.; Hyer, E.

    2013-10-01

    An aerosol optical depth (AOD) three-dimensional variational data assimilation technique is developed for the Gridpoint Statistical Interpolation (GSI) system for which WRF-Chem forecasts are performed with a detailed sectional model, the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC). Within GSI, forward AOD and adjoint sensitivities are performed using Mie computations from the WRF-Chem optical properties module, providing consistency with the forecast. GSI tools such as recursive filters and weak constraints are used to provide correlation within aerosol size bins and upper and lower bounds for the optimization. The system is used to perform assimilation experiments with fine vertical structure and no data thinning or re-gridding on a 12 km horizontal grid over the region of California, USA, where improvements on analyses and forecasts is demonstrated. A first set of simulations was performed, comparing the assimilation impacts of using the operational MODIS (Moderate Resolution Imaging Spectroradiometer) dark target retrievals to those using observationally constrained ones, i.e., calibrated with AERONET (Aerosol RObotic NETwork) data. It was found that using the observationally constrained retrievals produced the best results when evaluated against ground based monitors, with the error in PM2.5 predictions reduced at over 90% of the stations and AOD errors reduced at 100% of the monitors, along with larger overall error reductions when grouping all sites. A second set of experiments reveals that the use of fine mode fraction AOD and ocean multi-wavelength retrievals can improve the representation of the aerosol size distribution, while assimilating only 550 nm AOD retrievals produces no or at times degraded impact. While assimilation of multi-wavelength AOD shows positive impacts on all analyses performed, future work is needed to generate observationally constrained multi-wavelength retrievals, which when assimilated will generate size

  4. Dual Wavelength Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2010-01-01

    Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 m and Er at 2.9 m) as well as Nd:YAG (1.06 and 1.3 m) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.

  5. The general definition of the p97/valosin-containing protein (VCP)-interacting motif (VIM) delineates a new family of p97 cofactors.

    PubMed

    Stapf, Christopher; Cartwright, Edward; Bycroft, Mark; Hofmann, Kay; Buchberger, Alexander

    2011-11-01

    Cellular functions of the essential, ubiquitin-selective AAA ATPase p97/valosin-containing protein (VCP) are controlled by regulatory cofactors determining substrate specificity and fate. Most cofactors bind p97 through a ubiquitin regulatory X (UBX) or UBX-like domain or linear sequence motifs, including the hitherto ill defined p97/VCP-interacting motif (VIM). Here, we present the new, minimal consensus sequence RX(5)AAX(2)R as a general definition of the VIM that unites a novel family of known and putative p97 cofactors, among them UBXD1 and ZNF744/ANKZF1. We demonstrate that this minimal VIM consensus sequence is necessary and sufficient for p97 binding. Using NMR chemical shift mapping, we identified several residues of the p97 N-terminal domain (N domain) that are critical for VIM binding. Importantly, we show that cellular stress resistance conferred by the yeast VIM-containing cofactor Vms1 depends on the physical interaction between its VIM and the critical N domain residues of the yeast p97 homolog, Cdc48. Thus, the VIM-N domain interaction characterized in this study is required for the physiological function of Vms1 and most likely other members of the newly defined VIM family of cofactors.

  6. Activity of imipenem against VIM-1 metallo-beta-lactamase-producing Klebsiella pneumoniae in the murine thigh infection model.

    PubMed

    Daikos, G L; Panagiotakopoulou, A; Tzelepi, E; Loli, A; Tzouvelekis, L S; Miriagou, V

    2007-02-01

    The in-vivo activity of imipenem against VIM-1-producing Klebsiella pneumoniae (VPKP) was assessed in a thigh infection model in neutropenic mice. Animals were infected with three VPKP isolates (imipenem MICs 2, 4 and 32 mg/L, respectively) and a susceptible clinical isolate (MIC 0.125 mg/L) that did not produce any beta-lactamase with broad-spectrum activity. Bacterial density at the site of infection was determined after imipenem treatment (30 and 60 mg/kg every 2 h for 24 h). The log(10) reduction in CFU/thigh was greatest for the wild-type isolate, intermediate for the two imipenem-susceptible VPKP isolates, and lowest for the imipenem-resistant VPKP isolate. Whilst in-vivo imipenem activity appeared reduced against in-vitro susceptible VIM-1 producers compared with a VIM-1-negative control, an increased drug dosage could moderate this reduction. PMID:17328735

  7. Activity of imipenem against VIM-1 metallo-beta-lactamase-producing Klebsiella pneumoniae in the murine thigh infection model.

    PubMed

    Daikos, G L; Panagiotakopoulou, A; Tzelepi, E; Loli, A; Tzouvelekis, L S; Miriagou, V

    2007-02-01

    The in-vivo activity of imipenem against VIM-1-producing Klebsiella pneumoniae (VPKP) was assessed in a thigh infection model in neutropenic mice. Animals were infected with three VPKP isolates (imipenem MICs 2, 4 and 32 mg/L, respectively) and a susceptible clinical isolate (MIC 0.125 mg/L) that did not produce any beta-lactamase with broad-spectrum activity. Bacterial density at the site of infection was determined after imipenem treatment (30 and 60 mg/kg every 2 h for 24 h). The log(10) reduction in CFU/thigh was greatest for the wild-type isolate, intermediate for the two imipenem-susceptible VPKP isolates, and lowest for the imipenem-resistant VPKP isolate. Whilst in-vivo imipenem activity appeared reduced against in-vitro susceptible VIM-1 producers compared with a VIM-1-negative control, an increased drug dosage could moderate this reduction.

  8. N-body ray-tracing modeling of Saturn's rings for analysis of UVIS/VIMS optical depths and CIRS temperatures

    NASA Astrophysics Data System (ADS)

    Morishima, Ryuji; Spilker, Linda; Ballouz, Ronald-Louis; Richardson, Derek C.

    2016-10-01

    Various observations of Saturn's A and B rings indicate that ring particles are highly compacted near the mid-plane, making non-uniform structures. Such structures complicate deduction of properties of individual ring particles characterized by, for example, the albedo and the size distribution. Modeling using N-body simulations and ray-tracing calculations is one of the most promising approaches to understanding the dense rings of Saturn. We are developing a ray-tracing code that is applicable to analysis of UVIS/VIMS optical depths and CIRS temperatures. In the presentation, we report optical depth profiles of dense rings produced by large-scale N-body simulations (Ballouz et al. 2016; in preparation) and compare them with those from UVIS/VIMS occultation observations. Ballouz et al. (2016) find that prominent overstability wakes are produced at B ring locations either if the internal density is low and/or the friction forces are strong enough. For low internal density cases, the photometric optical depths become as high as those for the B ring, but rings are not necessarily most transparent when the line of sight is aligned to overstability wakes, in contrast to observations of the outer B ring (Colwell et al. 2007). For cases with high internal density and strong friction, rings become most transparent when the line of sight is roughly aligned to overstability wakes, but the photometric optical depths become much lower than the observed values due to highly transparent inter-wake gaps. These facts may indicate that small particles not considered in the simulations fill inter-wake gaps. We also report the progress of code modifications for analysis of CIRS temperature data. For calculations of the energy balance of ring particles, effects due to multiply scattered photometric light and to mutual heating between ring particles are added to the code.

  9. Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements

    USGS Publications Warehouse

    Jaumann, R.; Stephan, K.; Hansen, G.B.; Clark, R.N.; Buratti, B.J.; Brown, R.H.; Baines, K.H.; Newman, S.F.; Bellucci, G.; Filacchione, G.; Coradini, A.; Cruikshank, D.P.; Griffith, C.A.; Hibbitts, C.A.; McCord, T.B.; Nelson, R.M.; Nicholson, P.D.; Sotin, C.; Wagner, R.

    2008-01-01

    The surface of Enceladus consists almost completely of water ice. As the band depths of water ice absorptions are sensitive to the size of particles, absorptions can be used to map variations of icy particles across the surface. The Visual and Infrared Mapping Spectrometer (VIMS) observed Enceladus with a high spatial resolution during three Cassini flybys in 2005 (orbits EN 003, EN 004 and EN 011). Based on these data we measured the band depths of water ice absorptions at 1.04, 1.25, 1.5, and 2 ??m. These band depths were compared to water ice models that represent theoretically calculated reflectance spectra for a range of particle diameters between 2 ??m and 1 mm. The agreement between the experimental (VIMS) and model values supports the assumption that pure water ice characterizes the surface of Enceladus and therefore that variations in band depth correspond to variations in water ice particle diameters. Our measurements show that the particle diameter of water ice increases toward younger tectonically altered surface units with the largest particles exposed in relatively "fresh" surface material. The smallest particles were generally found in old densely cratered terrains. The largest particles (???0.2 mm) are concentrated in the so called "tiger stripes" at the south pole. In general, the particle diameters are strongly correlated with geologic features and surface ages, indicating a stratigraphic evolution of the surface that is caused by cryovolcanic resurfacing and impact gardening. ?? 2007 Elsevier Inc. All rights reserved.

  10. ISO terminological analysis of the VIM3 concepts 'quantity' and 'kind-of-quantity'

    NASA Astrophysics Data System (ADS)

    Dybkaer, René

    2010-06-01

    The recent third edition of the International Vocabulary of Metrology—Basic and General Concepts and Associated Terms (VIM3) (JCGM 200:2008 (Sèvres: BIPM); also ISO/IEC Guide 99:2007 3rd edn (Geneva: ISO)) has undergone important changes, not least by adhering to ISO International Standards on terminology work (ISO 704:2000 Terminology Work—Principles and Methods; ISO 1087-1:2000 Terminology Work—Vocabulary—Part 1: Theory and Application; ISO 10241:1992 International Terminology Standards—Preparation and Layout). A recent critique (Mari 2009 Metrologia 46 L11-L15)—based on Object-Oriented Analysis—centres on the meaning and relation of the two first and fundamental concepts 'quantity'Single quotation marks ('...') or bold type indicate a concept when necessary, double quotation marks ("...") a term or quotation. and the new entry 'kind-of-quantity'. This makes it timely to analyse the two concepts, their relation and their respective role in forming the generic hierarchical concept system of VIM3 from 'property' to individual quantities. It is suggested that 'kind-of-quantity' acts as a division criterionSynonyms are "criterion of subdivision", "type of characteristic(s)", see the annexe..

  11. Peeling the Onion: The Upper Surface of Mimas from Cassini VIMS

    NASA Astrophysics Data System (ADS)

    Buratti, Bonnie J.; Brown, R. H.; Clark, R. N.; Mosher, J. A.; Cruikshank, D. P.; Filacchione, G.; Baines, K. H.; Nicholson, P. D.

    2010-10-01

    Cloaked in light from Saturn and its rings, the medium-sized Saturnian satellite Mimas is difficult to observe form Earth, and it was the only major satellite not to have a close encounter by the Cassini spacecraft. Observations of the moon during Ring Plane Crossing in 1995 and by the Hubble Space Telescope established that the moon has a visual geometric albedo of greater than unity (Verbiscer et al. 2007, Science 315, 815) and a brighter trailing side (Buratti et al. 1998, Icarus 136, 223), suggesting it is being coated by the E-ring. Observations at opposition obtained by the Cassini Visual Infrared Mapping Spectrometer (VIMS) instrument between 0.4 and 5.2 microns show the moon has a surge similar to that seen on other icy bodies, increasing in brightness by over 30% in the last five degrees. During the closest nontargeted flyby by Cassini on February 13, 2010, when the Cassini spacecraft approached within 9500 km of Mimas, maps of the moon were obtained by VIMS. Water ice absorption bands in the central peak and crater rim of Herschel are deeper than those in the surrounding regions. Preliminary results indicate the water ice grain size decreases as the distance from the apex of motion increases. No constituents other than water ice have yet been identified. Funded by NASA.

  12. Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements

    NASA Astrophysics Data System (ADS)

    Jaumann, R.; Stephan, K.; Hansen, G. B.; Clark, R. N.; Buratti, B. J.; Brown, R. H.; Baines, K. H.; Newman, S. F.; Bellucci, G.; Filacchione, G.; Coradini, A.; Cruikshank, D. P.; Griffith, C. A.; Hibbitts, C. A.; McCord, T. B.; Nelson, R. M.; Nicholson, P. D.; Sotin, C.; Wagner, R.

    2008-02-01

    The surface of Enceladus consists almost completely of water ice. As the band depths of water ice absorptions are sensitive to the size of particles, absorptions can be used to map variations of icy particles across the surface. The Visual and Infrared Mapping Spectrometer (VIMS) observed Enceladus with a high spatial resolution during three Cassini flybys in 2005 (orbits EN 003, EN 004 and EN 011). Based on these data we measured the band depths of water ice absorptions at 1.04, 1.25, 1.5, and 2 μm. These band depths were compared to water ice models that represent theoretically calculated reflectance spectra for a range of particle diameters between 2 μm and 1 mm. The agreement between the experimental (VIMS) and model values supports the assumption that pure water ice characterizes the surface of Enceladus and therefore that variations in band depth correspond to variations in water ice particle diameters. Our measurements show that the particle diameter of water ice increases toward younger tectonically altered surface units with the largest particles exposed in relatively "fresh" surface material. The smallest particles were generally found in old densely cratered terrains. The largest particles (˜0.2 mm) are concentrated in the so called "tiger stripes" at the south pole. In general, the particle diameters are strongly correlated with geologic features and surface ages, indicating a stratigraphic evolution of the surface that is caused by cryovolcanic resurfacing and impact gardening.

  13. MULTI-WAVELENGTH OBSERVATIONS OF THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES WITH AIA/SDO. II. HYDRODYNAMIC SCALING LAWS AND THERMAL ENERGIES

    SciTech Connect

    Aschwanden, Markus J.; Shimizu, Toshifumi E-mail: shimizu.toshifumi@isas.jaxa.jp

    2013-10-20

    In this study we measure physical parameters of the same set of 155 M- and X-class solar flares observed with AIA/SDO as analyzed in Paper I, by performing a differential emission measure analysis to determine the flare peak emission measure EM{sub p} , peak temperature T{sub p} , electron density n{sub p} , and thermal energy E{sub th}, in addition to the spatial scales L, areas A, and volumes V measured in Paper I. The parameter ranges for M- and X-class flares are log (EM{sub p}) = 47.0-50.5, T{sub p} = 5.0-17.8 MK, n{sub p} = 4 × 10{sup 9}-9 × 10{sup 11} cm{sup –3}, and thermal energies of E{sub th} = 1.6 × 10{sup 28}-1.1 × 10{sup 32} erg. We find that these parameters obey the Rosner-Tucker-Vaiana (RTV) scaling law T{sub p}{sup 2}∝n{sub p} L and H∝T {sup 7/2} L {sup –2} during the peak time t{sub p} of the flare density n{sub p} , when energy balance between the heating rate H and the conductive and radiative loss rates is achieved for a short instant and thus enables the applicability of the RTV scaling law. The application of the RTV scaling law predicts power-law distributions for all physical parameters, which we demonstrate with numerical Monte Carlo simulations as well as with analytical calculations. A consequence of the RTV law is also that we can retrieve the size distribution of heating rates, for which we find N(H)∝H {sup –1.8}, which is consistent with the magnetic flux distribution N(Φ)∝Φ{sup –1.85} observed by Parnell et al. and the heating flux scaling law F{sub H} ∝HL∝B/L of Schrijver et al.. The fractal-diffusive self-organized criticality model in conjunction with the RTV scaling law reproduces the observed power-law distributions and their slopes for all geometrical and physical parameters and can be used to predict the size distributions for other flare data sets, instruments, and detection algorithms.

  14. Early signatures of large-scale field line opening. Multi-wavelength analysis of features connected with a "halo" CME event

    NASA Astrophysics Data System (ADS)

    Pohjolainen, S.; Vilmer, N.; Khan, J. I.; Hillaris, A. E.

    2005-04-01

    A fast "halo"-type coronal mass ejection (CME) associated with a two-ribbon flare, GOES class M 1.3, was observed on February 8, 2000. Soft X-ray and EUV images revealed several loop ejections and one wave-like moving front that started from a remote location, away from the flare core region. A radio type-II burst was observed near the trajectory of the moving soft X-ray front, although association with the CME itself cannot be ruled out. Large-scale dimmings were observed in EUV and soft X-rays, both in the form of disappearing transequatorial loops. We can pinpoint the time and the location of the first large-scale field-line opening by tracing the electron propagation paths above the active region and along the transequatorial loop system, in which large-scale mass depletion later took place. The immediate start of a type-IV burst (interpreted as an upward moving structure) which was located over a soft X-ray dimming region, confirms that the CME had lifted off. We compare these signatures with those of another halo CME event observed on May 2, 1998, and discuss the possible connections with the "magnetic breakout" model.

  15. First Report of an Extensively Drug-Resistant VIM-2 Metallo-β-Lactamase-Producing Brevundimonas diminuta Clinical Isolate

    PubMed Central

    Almuzara, Marisa N.; Barberis, Claudia M.; Rodríguez, Carlos H.; Famiglietti, Angela M. R.; Ramirez, Maria S.

    2012-01-01

    In the literature, only three Brevundimonas diminuta environmental isolates carrying metallo-β-lactamase genes were recently published. However, so far, no B. diminuta clinical isolates carrying these carbapenem resistance genes have been described. Here we report the first VIM-2 metallo-β-lactamase-producing B. diminuta clinical isolate obtained from an immunocompromised patient. PMID:22692741

  16. Saturn ring spokes: an overview of their near-infrared spectral properties from Cassini/VIMS data

    NASA Astrophysics Data System (ADS)

    D'Aversa, E.; Bellucci, G.; Nicholson, P. D.; Brown, R. H.; Altieri, F.; Carrozzo, F. G.

    2013-09-01

    The B ring of Saturn is known to periodically host weak elongated features called spokes. They have been clearly detected by the Voyagers, by the Hubble Space Telescope and by Cassini instruments ISS and VIMS. These observations were conducted during three different Saturn equinoxes in 1980, 1995, and 2009 respectively, bringing to the current view of the spoke's physical nature: thin clouds of fine electrically-charged grains levitating over the larger ring boulders. In respect to the previous available datasets, the VIMS one has widened our view of spokes outside the visible spectral range for the first time (longward of 1 micron). On the other hand, the VIMS spatial resolution is often comparable with the typical sizes of spokes, and considerable image processing is needed in order to enhance the spoke images and for the spectra extraction. Here we will report about advances in the spoke spectral analysis with VIMS data and will discuss the possible physical interpretations under the assumption of low spoke optical thickness.

  17. Synthesis of Metallo-β-Lactamase VIM-2 Is Associated with a Fitness Reduction in Salmonella enterica Serovar Typhimurium

    PubMed Central

    Cordeiro, Nicolás F.; Chabalgoity, José A.; Yim, Lucía

    2014-01-01

    Antibiotic resistance, especially due to β-lactamases, has become one of the main obstacles in the correct treatment of Salmonella infections; furthermore, antibiotic resistance determines a gain of function that may encompass a biological cost, or fitness reduction, to the resistant bacteria. The aim of this work was to determine in vitro if the production of the class B β-lactamase VIM-2 determined a fitness cost for Salmonella enterica serovar Typhimurium. To that end the gene blaVIM-2 was cloned into the virulent strain S. Typhimurium SL1344, using both the tightly regulated pBAD22 vector and the natural plasmid pST12, for inducible and constitutive expression, respectively. Fitness studies were performed by means of motility, growth rate, invasiveness in epithelial cells, and plasmid stability. The expression of blaVIM-2 was accompanied by alterations in micro- and macroscopic morphology and reduced growth rate and motility, as well as diminished invasiveness in epithelial cells. These results suggest that VIM-2 production entails a substantial fitness cost for S. Typhimurium, which in turn may account for the extremely low number of reports of metallo-β-lactamase-producing Salmonella spp. PMID:25136026

  18. Wavelength independent interferometer

    NASA Technical Reports Server (NTRS)

    Hochberg, Eric B. (Inventor); Page, Norman A. (Inventor)

    1991-01-01

    A polychromatic interferometer utilizing a plurality of parabolic reflective surfaces to properly preserve the fidelity of light wavefronts irrespective of their wavelengths as they pass through the instrument is disclosed. A preferred embodiment of the invention utilizes an optical train which comprises three off-axis parabolas arranged in conjunction with a beam-splitter and a reference mirror to form a Twyman-Green interferometer. An illumination subsystem is provided and comprises a pair of lasers at different preselected wavelengths in the visible spectrum. The output light of the two lasers is coaxially combined by means of a plurality of reflectors and a grating beam combiner to form a single light source at the focal point of the first parabolic reflection surface which acts as a beam collimator for the rest of the optical train. By using visible light having two distinct wavelengths, the present invention provides a long equivalent wavelength interferogram which operates at visible light wherein the effective wavelength is equal to the product of the wavelengths of the two laser sources divided by their difference in wavelength. As a result, the invention provides the advantages of what amounts to long wavelength interferometry but without incurring the disadvantage of the negligible reflection coefficient of the human eye to long wavelength frequencies which would otherwise defeat any attempt to form an interferogram at that low frequency using only one light source.

  19. Saturn's icy satellites investigated by Cassini-VIMS. II. Results at the end of nominal mission

    USGS Publications Warehouse

    Filacchione, G.; Capaccioni, F.; Clark, R.N.; Cuzzi, J.N.; Cruikshank, D.P.; Coradini, A.; Cerroni, P.; Nicholson, P.D.; McCord, T.B.; Brown, R.H.; Buratti, B.J.; Tosi, F.; Nelson, R.M.; Jaumann, R.; Stephan, K.

    2010-01-01

    We report the detailed analysis of the spectrophotometric properties of Saturn's icy satellites as derived by full-disk observations obtained by visual and infrared mapping spectrometer (VIMS) experiment aboard Cassini. In this paper, we have extended the coverage until the end of the Cassini's nominal mission (June 1st 2008), while a previous paper (Filacchione, G., and 28 colleagues [2007]. Icarus 186, 259-290, hereby referred to as Paper I) reported the preliminary results of this study. During the four years of nominal mission, VIMS has observed the entire population of Saturn's icy satellites allowing us to make a comparative analysis of the VIS-NIR spectral properties of the major satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus) and irregular moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso, Phoebe). The results we discuss here are derived from the entire dataset available at June 2008 which consists of 1417 full-disk observations acquired from a variety of distances and inclinations from the equatorial plane, with different phase angles and hemispheric coverage. The most important spectrophotometric indicators (as defined in Paper I: I/F continua at 0.55 ??m, 1.822 ??m and 3.547 ??m, visible spectral slopes, water and carbon dioxide bands depths and positions) are calculated for each observation in order to investigate the disk-integrated composition of the satellites, the distribution of water ice respect to "contaminants" abundances and typical regolith grain properties. These quantities vary from the almost pure water ice surfaces of Enceladus and Calypso to the organic and carbon dioxide rich Hyperion, Iapetus and Phoebe. Janus visible colors are intermediate between these two classes having a slightly positive spectral slope. These results could help to decipher the origins and evolutionary history of the minor moons of the Saturn's system. We introduce a polar representation of the spectrophotometric

  20. Geology of the Selk crater region on Titan from Cassini VIMS observations

    USGS Publications Warehouse

    Soderblom, J.M.; Brown, R.H.; Soderblom, L.A.; Barnes, J.W.; Jaumann, R.; Le Mouélic, Stéphane; Sotin, C.; Stephan, K.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2010-01-01

    Observations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located ???800. km north-northwest of the Huygens landing site. The crater rim-crest diameter is ???90. km; its floor diameter is ???60. km. A central pit/peak, 20-30. km in diameter, is seen; the ratio of the size of this feature to the crater diameter is consistent with similarly sized craters on Ganymede and Callisto, all of which are dome craters. The VIMS data, unfortunately, are not of sufficient resolution to detect such a dome. The inner rim of Selk crater is fluted, probably by eolian erosion, while the outer flank and presumed ejecta blanket appear dissected by drainages (particularly to the east), likely the result of fluvial erosion. Terracing is observed on the northern and western walls of Selk crater within a 10-15. km wide terrace zone identified in VIMS data; the terrace zone is bright in SAR data, consistent with it being a rough surface. The terrace zone is slightly wider than those observed on Ganymede and Callisto and may reflect differences in thermal structure and/or composition of the lithosphere. The polygonal appearance of the crater likely results from two preexisting planes of weakness (oriented at azimuths of 21?? and 122?? east of north). A unit of generally bright terrain that exhibits similar infrared-color variation and contrast to Selk crater extends east-southeast from the crater several hundred kilometers. We informally refer to this terrain as the Selk "bench." Both Selk and the bench are surrounded by the infrared-dark Belet dune field. Hypotheses for the genesis of the optically bright terrain of the bench include: wind shadowing in the lee of Selk crater preventing the encroachment of dunes, impact-induced cryovolcanism, flow of a fluidized-ejecta blanket (similar to the bright crater outflows observed on Venus), and erosion of a streamlined upland formed

  1. First Detection of Metallo-β-Lactamase VIM-2 in Pseudomonas aeruginosa Isolates from Colombia

    PubMed Central

    Villegas, Maria Virginia; Lolans, Karen; del Rosario Olivera, Maria; Suarez, Carlos José; Correa, Adriana; Queenan, Anne Marie; Quinn, John P.

    2006-01-01

    Carbapenem resistance rates in Pseudomonas aeruginosa isolates in Colombia, as in many South American countries, are high for reasons that remain unclear. From our nationwide network, we describe the first detection of the metallo-β-lactamase VIM-2 in clinical isolates of P. aeruginosa from multiple cities within Colombia. Metallo-β-lactamases were not detected in the two centers with the highest imipenem resistance rates. Clonality was noted in five of the eight centers with strains meeting the criteria for molecular typing. The high carbapenem resistance in P. aeruginosa in Colombia may be attributable to a combination of factors, including the presence of metallo-β-lactamases and nosocomial transmission. PMID:16377690

  2. Fast forward modeling of Titan's infrared spectra to invert VIMS/Cassini hyperspectral images

    USGS Publications Warehouse

    Rodriguez, S.; Le Mouélic, Stéphane; Rannou, P.; Combe, J.-P.; Corre, L.L.; Tobie, G.; Barnes, J.W.; Sotin, C.; Brown, R.H.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    The surface of Titan, the largest icy moon of Saturn, is veiled by a very thick and hazy atmosphere. The Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft, in orbit around Saturn since July 2004, conduct an intensive survey of Titan with the objective to understand the complex nature of the atmosphere and surface of the mysterious moon and the way they interact. Accurate radiative transfer modeling is necessary to analyze Titan's infrared spectra, but are often very computer resources demanding. As Cassini has gathered hitherto millions of spectra of Titan and will still observe it until at least 2010, we report here on the development of a new rapid, simple and versatile radiative transfer model specially designed to invert VIMS datacubes. ?? 2009 IEEE.

  3. Cassini/VIMS hyperspectral observations of the HUYGENS landing site on Titan

    USGS Publications Warehouse

    Rodriguez, S.; Le, Mouelic S.; Sotin, C.; Clenet, H.; Clark, R.N.; Buratti, B.; Brown, R.H.; McCord, T.B.; Nicholson, P.D.; Baines, K.H.

    2006-01-01

    Titan is one of the primary scientific objectives of the NASA-ESA-ASI Cassini-Huygens mission. Scattering by haze particles in Titan's atmosphere and numerous methane absorptions dramatically veil Titan's surface in the visible range, though it can be studied more easily in some narrow infrared windows. The Visual and Infrared Mapping Spectrometer (VIMS) instrument onboard the Cassini spacecraft successfully imaged its surface in the atmospheric windows, taking hyperspectral images in the range 0.4-5.2 ??m. On 26 October (TA flyby) and 13 December 2004 (TB flyby), the Cassini-Huygens mission flew over Titan at an altitude lower than 1200 km at closest approach. We report here on the analysis of VIMS images of the Huygens landing site acquired at TA and TB, with a spatial resolution ranging from 16 to14.4 km/pixel. The pure atmospheric backscattering component is corrected by using both an empirical method and a first-order theoretical model. Both approaches provide consistent results. After the removal of scattering, ratio images reveal subtle surface heterogeneities. A particularly contrasted structure appears in ratio images involving the 1.59 and 2.03 ??m images north of the Huygens landing site. Although pure water ice cannot be the only component exposed at Titan's surface, this area is consistent with a local enrichment in exposed water ice and seems to be consistent with DISR/Huygens images and spectra interpretations. The images show also a morphological structure that can be interpreted as a 150 km diameter impact crater with a central peak. ?? 2006 Elsevier Ltd. All rights reserved.

  4. Spectroscopy, morphometry, and photoclinometry of Titan's dunefields from Cassini/VIMS

    USGS Publications Warehouse

    Barnes, J.W.; Brown, R.H.; Soderblom, L.; Sotin, C.; Le, Mouelic S.; Rodriguez, S.; Jaumann, R.; Beyer, R.A.; Buratti, B.J.; Pitman, K.; Baines, K.H.; Clark, R.; Nicholson, P.

    2008-01-01

    Fine-resolution (500 m/pixel) Cassini Visual and Infrared Mapping Spectrometer (VIMS) T20 observations of Titan resolve that moon's sand dunes. The spectral variability in some dune regions shows that there are sand-free interdune areas, wherein VIMS spectra reveal the exposed dune substrate. The interdunes from T20 are, variously, materials that correspond to the equatorial bright, 5-??m-bright, and dark blue spectral units. Our observations show that an enigmatic "dark red" spectral unit seen in T5 in fact represents a macroscopic mixture with 5-??m-bright material and dunes as its spectral endmembers. Looking more broadly, similar mixtures of varying amounts of dune and interdune units of varying composition can explain the spectral and albedo variability within the dark brown dune global spectral unit that is associated with dunes. The presence of interdunes indicates that Titan's dunefields are both mature and recently active. The spectrum of the dune endmember reveals the sand to be composed of less water ice than the rest of Titan; various organics are consistent with the dunes' measured reflectivity. We measure a mean dune spacing of 2.1 km, and find that the dunes are oriented on the average in an east-west direction, but angling up to 10?? from parallel to the equator in specific cases. Where no interdunes are present, we determine the height of one set of dunes photoclinometrically to be between 30 and 70 m. These results pave the way for future exploration and interpretation of Titan's sand dunes. ?? 2007 Elsevier Inc. All rights reserved.

  5. Potentially active regions on Titan with Cassini/VIMS and Radar data: Terrestrial analogues.

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Le Mouélic, Stephane; Sotin, Christophe; Bratsolis, Emmanuel; Bampasidis, Georgios; Kyriakopoulos, Konstantinos; Moussas, Xenophon

    2010-05-01

    We present our study on Titan's geology in order to develop our current understanding of the satellite's active zones [1],[2]. The key aim is to study Titan's geology holistically, by means of internal activity and surface properties, in addition to terrestrial comparisons. We have applied the Principal Components Analysis (PCA) method in order to collect combined information of the seven infrared spectral windows, using the Cassini Mission Visual and Infrared Mapping Spectrometer (VIMS) data. The study areas for the moment are Tui Regio (located at 20°S, 130°W) and Hotei Regio (located at 26°S, 78°W). The main goal is to identify the composition as well as the alterations of the components that compose the possible calderas and lava flows [3], by using the principal components of the PCA method. Principal component analysis (PCA) is recommended, as our primary concern is to determine the minimum number of factors that will account for the maximum variance in the data in use in this particular multivariate analysis. Moreover, Cassini/Radar images have been processed [4] in order to study morphologically the active zones within the areas of Tui and Hotei Regio and to identify any analogues with terrestrial features. Both VIMS and Radar data [5] have provided significant information regarding the geology of the two areas, which should enable us to determine a possible internal activity as well as to identify superficial geologic structures. References [1] Nelson, R. M. (2009) Icarus 199, 429-441. [2] Solomonidou, A. (2009) European Planetary Science Congress Vol. 4, EPSC2009-710. [3] Sotin, C. (2005) Nature, Vol 435. [4] Bratsolis, E. & Sigelle, M. (2003) IEEE Transactions on Geoscience and Remote Sensing, 41, pp. 2890-2899. [5] Le Mouélic, S. (2008) Journal of Geophysical Research, Volume 113, Issue E4.

  6. Saturn's B Ring and Cassini Division from Cassini RSS, VIMS, and UVIS Occultations

    NASA Astrophysics Data System (ADS)

    French, Richard; Colwell, Joshua; Nicholson, Phillip; Hedman, Matthew; Marouf, Essam; Rappaport, Nicole J.; McGhee, Colleen; Batista, A.; de Silva, A.; Flores, S.; Geiling, N.; Graves, K.; Guo, L.; Kee, L. Huang. Y.; Larson, K.; Moreno, J.; Mowla, L.; Nelson, E.; Pang, Z.; Sanchez, T.; Stephens, K.; Strother, C.; Judd, K.; Snyderman, R.; Stroud, D.; Youngblood, A.

    Saturn's B ring demarcates the inner edge of the dynamically fascinating Cassini Division, replete with eccentric and circular ringlets and gaps. We present kinematical models for ringlets and gaps in the Cassini Division, and the outer edge of the B ring, from more than 100 individual Cassini occultations using RSS, VIMS, and UVIS instruments. Recent investigations of the B ring outer edge and Cassini Division features, using two decades of Earth-based and spacecraft occultation measurements, show hints of regularity amidst the complexity of the region. Hedman et al. (2010), using Cassini VIMS stellar occultation data and Cassini RSS and historical data from French et al. (2010), found a quasi-regular spacing of ringlets and gaps, with inner edges of gaps measurably non-circular and outer edges nearly circular. They proposed a dynamical mechanism whereby the non-circular B ring edge resonantly controls the structure of the Cassini Division gaps. The shape of the B ring edge is dominated by an m=2 mode, controlled by Mimas, although the dynamical interaction is still poorly understood. Cassini ISS images show the presence of multiple modes, possibly transient (Spitale et al. 2010). The long time series of the present data set, densely sampling the Cassini orbital tour from 2005-2009, coupled with the Voyager 1 and 2 data from 1980 and 1981, the widely-observed 28 Sgr stellar occultation of 1989, and Hubble Space Telescope stellar occultations in 1991 and 1995, provide the opportunity to determine the orbital elements and precession rates of the non-circular Cassini Division features, and to compare multi-mode libration and circulation models for the B ring edge. These are essential ingredients for detailed tests of dynamical models for the structure of the Cassini Division and its possible connection to the B ring.

  7. Millimeter wavelength propagation studies

    NASA Technical Reports Server (NTRS)

    Hodge, D. B.

    1974-01-01

    The investigations conducted for the Millimeter Wavelength Propagation Studies during the period December, 1966, to June 1974 are reported. These efforts included the preparation for the ATS-5 Millimeter Wavelength Propagation Experiment and the subsequent data acquisition and data analysis. The emphasis of the OSU participation in this experiment was placed on the determination of reliability improvement resulting from the use of space diversity on a millimeter wavelength earth-space communication link. Related measurements included the determination of the correlation between radiometric temperature and attenuation along the earth-space propagation path. Along with this experimental effort a theoretical model was developed for the prediction of attenuation statistics on single and spatially separated earth space propagation paths. A High Resolution Radar/Radiometer System and Low Resolution Radar System were developed and implemented for the study of intense rain cells in preparation for the ATS-6 Millimeter Wavelength Propagation Experiment.

  8. Laser wavelength metrology with color sensor chips.

    PubMed

    Jones, Tyler B; Otterstrom, Nils; Jackson, Jarom; Archibald, James; Durfee, Dallin S

    2015-12-14

    We present a laser wavelength meter based on a commercial color sensor chip. The chip consists of an array of photodiodes with different absorptive color filters. By comparing the relative amplitudes of light on the photodiodes, the wavelength of light can be determined. In addition to absorption in the filters, etalon effects add additional spectral features which improve the precision of the device. Comparing the measurements from the device to a commercial wavelength meter and to an atomic reference, we found that the device has picometer-level precision and picometer-scale drift over a period longer than a month. PMID:26699036

  9. Potentially active regions on Titan: New processing of Cassini/VIMS data

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Hirtzig, M.; Bratsolis, E.; Bampasidis, G.; Coustenis, A.; Kyriakopoulos, K.; Le Mouélic, S.; Stephan, K.; Jaumann, R.; Drossart, P.; Sotin, C.; St. Seymour, K.; Moussas, X.

    2012-04-01

    The Cassini Visual and Infrared Mapping Spectrometer (VIMS) obtained data of Titan's surface from flybys performed during the last seven years. In the 0.8-5.2 µm range, these spectro-imaging data showed that the surface consists of a multivariable geological terrain hosting complex geological processes. The data from the seven narrow methane spectral "windows" centered at 0.93, 1.08, 1.27, 1.59, 2.03, 2.8 and 5 µm provide some information on the lower atmospheric context and the surface parameters that we want to determine. Atmospheric scattering and absorption need to be clearly evaluated before we can extract the surface properties. We apply here a statistical method [1, 2] and a radiative transfer method [3, 1] on three potentially "active" regions on Titan, i.e. regions possibly subject to change over time (in brightness and/or in color etc) [4]: Tui Regio (20°S, 130°W) [5], a 1,500-km long flow-like figure, Hotei Regio (26°S, 78°W) [6], a 700-km wide volcanic-like terrain, and Sotra Facula (15°S, 42°W) [7], a 235-km in diameter area. With our method of Principal Component Analysis (PCA) we have managed to isolate specific regions of distinct and diverse chemical composition. We have tested this method on the previously studied Sinlap crater [8], delimitating compositional heterogeneous areas compatible with the published conclusions by Le Mouélic et al. (2008). Our follow-up method focuses on retrieving the surface albedo of the three areas and of the surrounding terrains with different spectral response by applying a radiative transfer (RT) code. We have used as input most of the Cassini HASI and DISR measurements, as well as new methane absorption coefficients [9], which are important to evaluate the atmospheric contribution and to allow us to better constrain the real surface alterations, by comparing the spectra of these regions. By superposing these results onto the PCA maps, we can correlate composition and morphology. As a test case, we used

  10. Coherent Backscattering Effect in Icy Satellites: Model, Cassini VIMS, and Ground-Based Near-Infrared Spectra

    NASA Astrophysics Data System (ADS)

    Pitman, Karly M.; Kolokolova, L.; Verbiscer, A. J.

    2013-10-01

    Compositional mapping of icy satellite surfaces is usually based on correlating spectral absorption band depths with the abundance of ice/non-ice species and/or particle size alone. However, absorption band depths and shapes also depend on observation geometry, specifically the solar phase angle α. The constructive interference of light that is responsible for the coherent backscattering effect (CBE) should significantly alter the interpretation of spacecraft spectra obtained at α < 2 degrees in particular (Helfenstein et al. 1997 Icarus 128, 2-14), but the magnitude of the CBE on band depth has not yet been quantified or studied in detail. In this work, we explore the relationship between α, spectral band depth and shape caused by CBE for both Cassini Visual & Infrared Mapping Spectrometer (VIMS) and ground-based near-infrared observations of bright and dark satellites. We report numerical CBE modeling performed using the publicly available multisphere T-matrix (MSTM) computer code to simulate the change in absorption bands with the solar phase angle seen in the spectra of icy bodies. We compare these models to Cassini VIMS extracted I/F spectra for selected icy satellites (e.g., Rhea, Iapetus, Enceladus) as well as ground-based λ = 0.9 - 2.4 μm spectra of Tethys, Dione, Iapetus, Rhea, and Enceladus acquired using Triplespec (R=3000) at Apache Point Observatory, New Mexico. Such results ultimately place limits on the size and packing fraction of icy satellite regolith particles and aid in interpretations of the structure, composition, and evolution of icy satellites. This work is supported by NASA’s Outer Planets Research program (NNX12AM76G; PI Pitman), Planetary Astronomy program (NNX09AD06G; PI Verbiscer), and NASA’s Advanced Supercomputing Division. Calibrated Cassini VIMS data cubes appear courtesy of B. J. Buratti and the Cassini VIMS team.

  11. Structural diversity of the 3-micron absorption band in Enceladus’ plume from Cassini VIMS: Insights into subsurface environmental conditions

    NASA Astrophysics Data System (ADS)

    Dhingra, Deepak; Hedman, Matthew M.; Clark, Roger N.

    2015-11-01

    Water ice particles in Enceladus’ plume display their diagnostic 3-micron absorption band in Cassini VIMS data. These near infrared measurements of the plume also exhibit noticeable variations in the character of this band. Mie theory calculations reveal that the shape and location of the 3-micron band are controlled by a number of environmental and structural parameters. Hence, this band provides important insights into the properties of the water ice grains and about the subsurface environmental conditions under which they formed. For example, the position of the 3-micron absorption band minimum can be used to distinguish between crystalline and amorphous forms of water ice and to constrain the formation temperature of the ice grains. VIMS data indicates that the water ice grains in the plume are dominantly crystalline which could indicate formation temperatures above 113 K [e.g. 1, 2]. However, there are slight (but observable) variations in the band minimum position and band shape that may hint at the possibility of varying abundance of amorphous ice particles within the plume. The modeling results further indicate that there are systematic shifts in band minimum position with temperature for any given form of ice but the crystalline and amorphous forms of water ice are still distinguishable at VIMS spectral resolution. Analysis of the eruptions from individual source fissures (tiger stripes) using selected VIMS observations reveal differences in the 3-micron band shape that may reflect differences in the size distributions of the water ice particles along individual fissures. Mie theory models suggest that big ice particles (>3 micron) may be an important component of the plume.[1] Kouchi, A., T. Yamamoto, T. Kozasa, T. Kuroda, and J. M. Greenberg (1994) A&A, 290, 1009-1018 [2] Mastrapa, R. M. E., W. M. Grundy, and M. S. Gudipati (2013) in M. S. Gudipati and J. Castillo-Rogez (Eds.), The Science of Solar System Ices, pp. 371.

  12. Titan's cloud seasonal activity from winter to spring with Cassini/VIMS

    USGS Publications Warehouse

    Rodriguez, S.; Le, Mouelic S.; Rannou, P.; Sotin, C.; Brown, R.H.; Barnes, J.W.; Griffith, C.A.; Burgalat, J.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2011-01-01

    Since Saturn orbital insertion in July 2004, the Cassini orbiter has been observing Titan throughout most of the northern winter season (October 2002-August 2009) and the beginning of spring, allowing a detailed monitoring of Titan's cloud coverage at high spatial resolution with close flybys on a monthly basis. This study reports on the analysis of all the near-infrared images of Titan's clouds acquired by the Visual and Infrared Mapping Spectrometer (VIMS) during 67 targeted flybys of Titan between July 2004 and April 2010.The VIMS observations show numerous sporadic clouds at southern high and mid-latitudes, rare clouds in the equatorial region, and reveal a long-lived cloud cap above the north pole, ubiquitous poleward of 60??N. These observations allow us to follow the evolution of the cloud coverage during almost a 6-year period including the equinox, and greatly help to further constrain global circulation models (GCMs). After 4. years of regular outbursts observed by Cassini between 2004 and 2008, southern polar cloud activity started declining, and completely ceased 1. year before spring equinox. The extensive cloud system over the north pole, stable between 2004 and 2008, progressively fractionated and vanished as Titan entered into northern spring. At southern mid-latitudes, clouds were continuously observed throughout the VIMS observing period, even after equinox, in a latitude band between 30??S and 60??S. During the whole period of observation, only a dozen clouds were observed closer to the equator, though they were slightly more frequent as equinox approached. We also investigated the distribution of clouds with longitude. We found that southern polar clouds, before disappearing in mid-2008, were systematically concentrated in the leading hemisphere of Titan, in particular above and to the east of Ontario Lacus, the largest reservoir of hydrocarbons in the area. Clouds are also non-homogeneously distributed with longitude at southern mid

  13. The Long Wavelength Array

    NASA Astrophysics Data System (ADS)

    Taylor, G. B.

    2006-08-01

    The Long Wavelength Array (LWA) will be a new, open, user-oriented astronomical instrument operating in the poorly explored window from 20-80 MHz at arcsecond level resolution and mJy level sensitivity. Key science drivers include (1) acceleration, propagation, and turbulence in the ISM, including the space-distribution and spectrum of Galactic cosmic rays, supernova remnants, and pulsars; (2) the high redshift universe, including the most distant radio galaxies and clusters - tools for understanding the earliest black holes and the cosmological evolution of Dark Matter and Dark Energy; (3) planetary, solar, and space science, including space weather prediction and extra-solar planet searches; and (4) the radio transient universe: including the known (e.g., SNe, GRBs) and the unknown. Because the LWA will explore one of the last and least investigated regions of the spectrum, the potential for new discoveries, including new classes of physical phenomena, is high, and there is a strong synergy with exciting new X-ray and Gamma-ray measurements, e.g. for cosmic ray acceleration, transients, and galaxy clusters. Operated by the University of New Mexico on behalf of the South West Consortium (SWC) the LWA will also provide a unique training ground for the next generation of radio astronomers. Students may also put skills learned on the LWA to work in computer science, electrical engineering, and the communications industry, among others. The development of the LWA will follow a phased build, which benefits from lessons learned at each phase. Four university-based Scientific Testing and Evaluation (ST&E) teams with different areas of concentration (1. High resolution imaging and particle acceleration; 2. Wide field imaging and large scale structures; 3. Ionosphere, and 4. RFI suppression and transient detection) will provide the feedback needed to assure that science objectives are met as the build develops. Currently in its first year of construction funding, the LWA

  14. Equatorial belt of Titan: Aaru Region as seen by VIMS/Cassini

    NASA Astrophysics Data System (ADS)

    Florian Brossier, Jeremy; Rodriguez, Sébastien; Maltagliati, Luca; Le Mouélic, Stéphane; Solomonidou, Anezina; Coustenis, Athena; Hirtzig, Mathieu; Jaumann, Ralf; Brown, Robert H.

    2016-10-01

    Since eleven years of observation, near-infrared imaging data from the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini1 reveal a variety of surface units that are compositionally and structurally distinct2, 3. The analysis of these units enables constraining the surface composition of Titan, which is of prime importance for modelling Titan's interior, surface, and atmosphere, particularly in the search for an endogenic methane source. For this study, we investigate a selection of units of interest seen in VIMS data by comparatively applying an empirical correction4, 5 and a radiative transfer code6-8 in order to correct for atmospheric contributions and retrieve surface albedo. SAR swaths from the Radar instrument are also used for geomorphological mapping purposes. We focus on the region of Aaru, located in the equatorial belt and centered at 10°N and 340°W, where several geological features have been identified: (1) infrared-brown dunes material; (2) a strongly eroded impact crater named Paxsi9 (3) mountainous and infrared-bright plateaus; and (4) infrared-blue areas devoid of dunes (similar to those seen in other regions probably enriched in water-ice, such as Chusuk Planitia10). By using our radiative transfer model, we estimate the surface albedo of regions of our interest within different infrared units of the Aaru region and compare with spectra of surface candidates, starting with water-ice and tholins. As seen in the similar study over Sinlap crater and its surroundings11, this method of analysis allows understanding of the compositional and structural relations between the different spectral units.References: 1 Brown, R. H. et al. (2005) SSR. 2 Barnes, J. W. et al. (2007) Icarus, 186 (1). 3 Soderblom, L. A. et al. (2007) PSS, 55 (13). 4 Cornet, T. et al. (2012) Icarus, 218 (2). 5 Le Mouélic, S. et al. (2012) PSS, 73 (1). 6 Hirtzig, M. et al. (2013) Icarus, 226 (1). 7 Solomonidou, A. et al. (2014) JGR, 119 (8). 8 Maltagliati, L. et al

  15. The Polar Winds of Saturn as Determined by Cassini/VIMS: Seasonally Variable or Not?

    NASA Astrophysics Data System (ADS)

    Momary, Thomas W.; Baines, K. H.; Brown, R. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.; Sotin, C.; Cassini/VIMS Science Team

    2013-10-01

    The high inclination of Cassini's current orbit allows VIMS to once again obtain spectacular views of Saturn’s poles, not seen since 2008. We present new imagery and investigate the effect of seasonal variability on Saturn’s polar winds. The north pole now basks in spring daylight and we again observe the long-enduring northern Polar Hexagon, discovered in Voyager imagery by Godfrey (Icarus 76, 335-356, 1988). This feature seemed to stay fixed in a rotational system defined by the Voyager-era radio rotation rate (Desch & Kaiser, Geophys. Res. Lett, 8, 253-256, 1981) in both original Voyager and 2008 VIMS observations. Yet new images indicate a shift, with the hexagon rotating ~10° of longitude from Nov. 2012 to May 2013. Discrete clouds still race around the edges of the 5-μm-bright hexagon at speeds of ~100 m/s, as we observed in 2008 (Baines, Momary, et al., Plan. Space. Sci 57, 1671-1681, 2009). We also recover a massive storm system residing just inside the hexagon edge at ~80° N. lat. Since 2008, this storm has shifted poleward by 1.5° and turned 5 μm dark (cloudy), where it was 5 μm bright when last observed (i.e. cloud free). It now moves zonally faster at ~25 m/s vs. ~14 m/s in 2008. This enduring "shepherd" storm may force and maintain the hexagon shape. We also recover twin 5-μm-dark storms (Snake Eyes) moving slowly at ~15 m/s near 67° N lat. However, while the two features appear to maintain a relatively constant zonal separation on average (14° ), with the trailing feature remaining near 67° N lat., the leading storm appears to oscillate ~1° in latitude and drift in longitude. At the south pole, discrete clouds whirl, now in darkness, around a hurricane-like vortex consisting of a cloudless "eye" extending at least 1 bar deeper than surrounding rings of clouds. These clouds still appear to be moving as a classical vortex with winds reaching a maximum of ~200 m/s near 87° S lat. and then falling off to zero at the pole. In contrast

  16. Cassini VIMS Spectra of the Earth from Saturn Orbit: an Extrasolar Planet Analog

    NASA Astrophysics Data System (ADS)

    Clark, Roger Nelson; Hedman, Matthew M.; Brown, Robert H.; Filacchione, Gianrico; Nicholson, Philip D.; Barnes, Jason W.

    2015-11-01

    Cassini VIMS has obtained spectra of the Earth while in Saturn orbit making observations of the Saturn system when the sun was behind Saturn. The observations, made in September 15, 2006 and July 19, 2013 are visible-near-infrared spectra (0.35 - 5.1 microns) of the Earth obtained at the furthest distance from the sun to date. The Earth was sub-pixel, 0.0088 milliradian in 2013 and 0.0085 milliradian in 2006, and the signal-to-noise ratio is low. A VIMS pixel IFOV is 0.25 x 0.5milliradian. As such, these data are likely representative of the first spectra that might be obtained of extrasolar terrestrial-like planets. What information can be derived from such remote observations? The observation made in 2013 had a phase angle of 97 degrees with multipleimage cubes providing a higher S/N average. The 2006 observation was made at a phase angle of 33 degrees but is a single cube, 1 pixel. The 2006 observation has Africa dominant on the disk, while the 2013 observation is mostly ocean with part of South America in sunlight. The 2013 visible data show clear signatures of Rayleigh scattering but this blue coloring can be from both the atmosphere and/or ocean. The 2006 data show a flatter spectrum, a signature of land. Both observations include the Moon in the field of view. The 0.35-2.5 micron spectral range shows significant absorption due to H2O liquid + gas. The thermal signature is very strong with the highest S/N of the entire spectrum. The best fit preliminary temperatures are 280 K with a small 380 K component (from the Moon), putting at least some of the planet in the goldilocks zone. There is strong absorption by CO2 at 4.25 microns in both 2013 and 2006 data. There is possible detection of chlorophyll and oxygen emission but higher S/N would be required for a positive detection. The spectral profile of the thermal emission could be used to constrain the diameter of the planet. If such spectra were obtained of an extrasolar planet, we could conclude that the

  17. The Sleepy Anticyclonic Eye of the Great Storm on Saturn as seen by Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Momary, Thomas W.; Baines, Kevin; Badman, Sarah; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger Nelson; Nicholson, Philip D.; Sotin, Christophe

    2016-10-01

    The Great Storm that erupted at 34o N on Saturn in late 2010 obliterated the String of Pearls feature in that region and left a lasting remnant – a clear 5-μm bright zone around the entire globe inhabited by a lone anticyclone that persists to the present time. We have observed this enduring oval with Cassini/VIMS since 2011 and note that it exhibits a somewhat latitudinally oscillatory nature as it bobs in Saturn's zonal currents. Centered at 35.9o planetocentric latitude in May 2011, it drifted northward to 37.8o in 2012, floated near 37o through 2013, settled as far south as ~36.5o in 2014, bobbed northward to ~37o in 2015, and now appears to reside at about ~36.3o in early 2016. It has also periodically bumped up against the dark band above it, spinning off material in 2013 and 2015. We measured a prograde zonal drift speed of ~22 m/s in 2012, increasing as much as 60% through 2013, then relaxing back to a more moderate ~15 m/s in 2014 and 2015. Early indications are that it has slowed considerably in 2016 to about ~4.7 m/s, which would be the slowest drift rate we've yet measured for it, but still consistent with the Voyager Wind Profile for this region. The feature has varied in size over time as it spins, spanning 4.9o x 3.2o in 2011, elongating to 7.3o x 2.9o by 2013, contracting to 5.5o x 2.9o in 2014, enlarging again to ~9o x ~4o in 2015, and currently averaging ~6.6o x ~3.5o in 2016. It currently is symmetrically oval in shape. It has varied in terms of cloudiness, being ~ 90% 5-μm dark (obscured) in 2011, whereas by 2013 it was mostly bright (clear) with a thin dark edge, returning to ~90% dark in 2015, and currently about 98% obscured. We have used night observations to isolate thermal flux, and found that the mean 5-μm flux coming from the anticyclone has diminished steadily by about 50% since 2013. We are monitoring this trend. The entire storm latitude of ~34o N itself has remained persistently 5-μm bright since 2011, but is slowly dimming as

  18. Spectroscopic Identification of E-Ring Deposits on Enceladus Using Cassini-Vims Dat

    NASA Astrophysics Data System (ADS)

    Scipioni, F.; Schenk, P.; Tosi, F.

    2014-12-01

    Enceladus' surface is composed mostrly of pure water ice. The Cassini spacecraft has observed present-day geologic activity at the moon's South Polar region (the so-called "Tiger Stripes"). Plumes of micron-sized particles composed of water ice and other contaminants (CO2, NH3, CH4) erupting from this region are the major source of Saturn's E-ring. Some of this material, however, falls on Enceladus' surface to form deposits that extend to the north at ~220°E and ~40°E and whose highest concentration is at the south pole. The Cassini VIMS spectrometer acquires hyperspectral data in the 0.3-5.1 μm spectral range. We selected VIMS cubes of Enceladus in the IR range (0.8-5.1 μm), and minimized photometric effects due to different illumination conditions by normalizing all spectra at 2.23 μm. We aim to identify E-ring deposits across Enceladus' surface through the variation in band depth of the main water-ice spectral features located at 1.25, 1.5, and 2.0 μm. Since plumes deposits on the surface undergo darkening processes for less time than surrounding terrains, they appear brighter and so the water-ice absorption bands must be deeper. For all pixels in the selected cubes, we measured the band depths for the main water-ice absorptions and the height of the 3.6 μm reflection peak, whose value relates to grain size. To characterize the global variation of water-ice band depths across Enceladus, we divided the surface into a 1°x1° grid and then averaged the band depths and peak values inside each square cell. This approach clearly identifies plums deposits. As expected, the highest concentrations occur at Enceladus' south pole, where band depths values are the deepest across the entire moon's surface. Our results confirm that plume particles fall in north-oriented patterns at ~40°E and ~220°E, and disappear around ~0°E and ~180°E. In addition, we observed a possible non-plume related regional variation in all major water ice absorption bands on the leading

  19. Scales

    MedlinePlus

    Scales are a visible peeling or flaking of outer skin layers. These layers are called the stratum ... Scales may be caused by dry skin, certain inflammatory skin conditions, or infections. Eczema , ringworm , and psoriasis ...

  20. Investigations of Saturn’s Main Rings over Broad Range of Wavelengths

    NASA Astrophysics Data System (ADS)

    Spilker, Linda J.; Deau, Estelle; Morishima, Ryuji; Filacchione, Gianrico; Hedman, Matt; Nicholson, Phil; Colwell, Josh; Bradley, Todd; Showalter, Mark; Pilorz, Stu; Brooks, Shawn; Ciarniello, Mauro

    2015-11-01

    An abundance of information about the characteristics of Saturn’s ring particles and their regolith can be obtained by comparing the changes in their brightness, color and temperature with changing viewing geometry over a wide range of wavelengths from ultraviolet through the thermal infrared. Data from Cassini’s Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly studied using data from the lit and unlit main rings at multiple geometries and solar elevations over 11 years of the Cassini mission. Using multi-wavelength data sets allows us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation.CIRS temperatures, ISS colors and UVIS brightness appear to vary noticeably with phase angle, but are not a strong function of spacecraft elevation angle. Color, temperature and brightness dependence on solar elevation angle are also observed. VIMS observations show that the infrared ice absorption band depths change with the solar phase angle, in particular between 0-20° and at high phase. This trend indicates that single scattering approximation is correct only at low phases (<20°) while at high phase multiple scattering must be taken into account.These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith, as well as scattering between individual particles or clumps in a many-particle-thick layer. Initial results from our joint studies will be presented.This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA

  1. Multi-wavelength Studies Of Saturn's Rings To Constrain Ring Particle Properties And Ring Structure

    NASA Astrophysics Data System (ADS)

    Spilker, Linda J.; Deau, E.; Morishima, R.; Filacchione, G.; Hedman, M. M.; Nicholson, P.; Bradley, T.; Colwell, J.

    2012-10-01

    The characteristics of Saturn’s ring particles and their regoliths are examined by modeling variations in brightness, color, temperature and spectral parameters with changing viewing geometry over a wide range of wavelengths. Data from Cassini CIRS, ISS, VIMS and UVIS scans of the lit and unlit main rings at multiple geometries and solar elevations are used. Using multi-wavelength data sets allows us to test different thermal models by combining effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, and particle spin rate and spin axis orientation. Over a range of solar elevations the CIRS temperature and ISS color variations are confined primarily to phase angle with only small differences from changing spacecraft elevation. Color and temperature dependence with varying solar elevation angle are also observed. Brightness dependence with changing solar elevation angle and phase angle is observed with UVIS. VIMS observations show that IR water ice absorption band depths are a very weak function of phase angle, out to 140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces of the clumps, as well as a contribution from scattering between individual particles in a many-particle-thick layer. Preliminary results from our joint studies will be presented. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2012 California Institute of Technology. Government sponsorship is acknowledged.

  2. Virtual interactive musculoskeletal system (VIMS) in orthopaedic research, education and clinical patient care

    PubMed Central

    Chao, Edmund YS; Armiger, Robert S; Yoshida, Hiroaki; Lim, Jonathan; Haraguchi, Naoki

    2007-01-01

    The ability to combine physiology and engineering analyses with computer sciences has opened the door to the possibility of creating the "Virtual Human" reality. This paper presents a broad foundation for a full-featured biomechanical simulator for the human musculoskeletal system physiology. This simulation technology unites the expertise in biomechanical analysis and graphic modeling to investigate joint and connective tissue mechanics at the structural level and to visualize the results in both static and animated forms together with the model. Adaptable anatomical models including prosthetic implants and fracture fixation devices and a robust computational infrastructure for static, kinematic, kinetic, and stress analyses under varying boundary and loading conditions are incorporated on a common platform, the VIMS (Virtual Interactive Musculoskeletal System). Within this software system, a manageable database containing long bone dimensions, connective tissue material properties and a library of skeletal joint system functional activities and loading conditions are also available and they can easily be modified, updated and expanded. Application software is also available to allow end-users to perform biomechanical analyses interactively. Examples using these models and the computational algorithms in a virtual laboratory environment are used to demonstrate the utility of these unique database and simulation technology. This integrated system, model library and database will impact on orthopaedic education, basic research, device development and application, and clinical patient care related to musculoskeletal joint system reconstruction, trauma management, and rehabilitation. PMID:17343764

  3. Short wavelength laser

    DOEpatents

    Hagelstein, P.L.

    1984-06-25

    A short wavelength laser is provided that is driven by conventional-laser pulses. A multiplicity of panels, mounted on substrates, are supported in two separated and alternately staggered facing and parallel arrays disposed along an approximately linear path. When the panels are illuminated by the conventional-laser pulses, single pass EUV or soft x-ray laser pulses are produced.

  4. Short wavelength laser

    DOEpatents

    Hagelstein, Peter L.

    1986-01-01

    A short wavelength laser (28) is provided that is driven by conventional-laser pulses (30, 31). A multiplicity of panels (32), mounted on substrates (34), are supported in two separated and alternately staggered facing and parallel arrays disposed along an approximately linear path (42). When the panels (32) are illuminated by the conventional-laser pulses (30, 31), single pass EUV or soft x-ray laser pulses (44, 46) are produced.

  5. New processing of Cassini/VIMS data on potentially geologically varying regions

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Hirtzig, M.; Bratsolis, E.; Bampasidis, G.; Coustenis, A.; Kyriakopoulos, K.; Le Mouélic, S.; Rodriguez, S.; Jaumann, R.; Stephan, K.; Drossart, P.; Sotin, C.; Brown, R. H.; Seymour, K.; Moussas, X.

    2012-09-01

    We present a study of Titan's geology with a view to enhance our current understanding of the satellite's potentially geologically varying regions. We apply here a statistical method, the Principal Component Analysis (PCA) [1, 2] and a radiative transfer method [3, 1] on three potentially "active" regions on Titan, i.e. regions possibly subject to change over time (in brightness and/or in color etc) [4] namely Tui Regio, Hotei Regio, and Sotra Facula. With our method of PCA we have managed to isolate specific regions of distinct and diverse chemical composition. Then, with our follow-up RT method, we retrieved the surface albedo of the three isolated regions and of the surrounding terrains with different spectral response. These methods enabled us to evaluate the atmospheric contribution and allowed us to better constrain the real surface alterations, by comparing the spectra of these regions. Finally, the temporal surface variation of Hotei Regio as suggested by Nelson et al. 2009 [5], has been tested through the use of the RT method while we have superimposed this area's Cassini Visual and Infrared Mapping Spectrometer (VIMS) and RADAR data in order to 'view' the morphological potential. Even though we have used exactly the same dataset as Nelson and coauthors in 2009, we did not detect any significant surface albedo variations over time; this led us to revise the definition of "active" regions: even if these regions have not visually changed over the course of the Cassini mission, the determination of the chemical composition and the correlation with the morphological structures [6] observed in these areas do not rule out that past and/or ongoing cryovolcanic processes are still a possible interpretation.

  6. Constrains on the nature of Titan's surface from Cassini/VIMS and RADAR

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Lopes, Rosaly; Rodriguez, Sebastien; Drossart, Pierre; Schmitt, Bernard; Philippe, Sylvain; Malaska, Michael; Janssen, Michael; Maltagliati, Luca; Lawrence, Kenneth; Jaumann, Ralf; Sohl, Frank; Stephan, Katrin; Brown, Robert; Bratsolis, Emannuel; Matsoukas, Christos

    2016-04-01

    Cassini remote-sensing instruments for more than 10 years now and in situ by the Huygens instruments back in 2005. For the surface, the presence of diverse terrains in terms of morphology and composition suggest both exogenic and endogenic processes to be at play. In this study, we investigate the surface and atmospheric contributions from the Visual and Infrared Mapping Spectrometer (VIMS) spectro-imaging data by use of a radiative transfer code in the near-IR range and the RADAR/SAR data for the distinction of geomorphological units. We focus here on those units identified in Lopes et al. (2010, 2015) [1; 2] and Malaska et al. (2015) [3]: mountains, plains, labyrinths, dune fields, and the areas previously suggested to have experienced change such as the possible cryovolcanic and evaporite features (Barnes et al. 2013; Solomonidou et al. 2014; 2015) [4; 5; 6]. With the use of a recently updated radiative transfer code, we evaluate the atmospheric contribution and extract the pure surface albedo information for each region of interest. The extracted albedo shapes and values are then tested against spectra of constituents that are considered to be the best Titan candidate materials, including a very recent library of Titan ice spectra [7]. We find that many of the units show compositional variations while units of significant geomorphological differences seem to consist of very similar materials, which help us provide implications on their endogenic or exogenic origin. Preliminary results on the chemical composition of the regions that have shown temporal changes are also presented. References: [1] Lopes, R.M.C., et al.: Icarus, 205, 540-558, 2010; [2] Lopes, R.M.C., et al.: Icarus, in press; [3] Malaska, M., et al. : Icarus, submitted; [4] Barnes, J., et al.: Planetary Science, 2:1, 2013; [5] Solomonidou, A., et al.: JGR, 119, 1729-1747, 2014; [6] Solomonidou, A., et al.: Icarus, in press; [7] Schmitt, B., et al.: GhoSST datacase (ghosst.osug.fr).

  7. Geological mapping and temporal survey of Ontario Lacus on Titan from 2005 to 2009, using VIMS, ISS and Radar data

    NASA Astrophysics Data System (ADS)

    Cornet, T.; Bourgeois, O.; Le Mouélic, S.; Rodriguez, S.; Tobie, G.; Sotin, C.; Barnes, J. W.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

    2010-12-01

    In June 2004 and July 2005, the ISS multispectral camera onboard the Cassini spacecraft imaged a 235 km-long and 75 km-wide dark feature near the south pole of Titan (McEwen et al., 2005). By comparison with other landforms observed near Titan’s north pole with the Radar instrument (Stofan et al., 2007), this feature has been interpreted as an hydrocarbon lake and named Ontario Lacus. Other observations of the lake, by the VIMS hyperspectral camera in December 2007 and the Radar altimeter in December 2008 are consistent with a liquid filled lake (Brown et al., 2008, Barnes et al., 2009), which lies in an extremely flat depression (Lorenz et al., 2009). In March 2009, VIMS acquired new hyperspectral cubes with a spatial resolution similar to the first ones. Finally, the new Radar observations in SAR mode in June and July 2009, 3 months after the VIMS observation, provided the first spatially resolved images of the lake. By merging all these data sets, we performed an integrated geomorphological and compositional study of Ontario Lacus and its surroundings. Comparisons with optical and radar satellite images of analogous landforms in the Etosha Basin, a semi-arid region of Namibia, allowed us to produce an interpretative geological map of Ontario Lacus in 2009. We also checked for potential surface changes of the lake between 2005 and 2009, i.e. during the austral summer and autumn. To achieve this work, we developed a new empirical processing method to remove atmospheric effects in VIMS images and to improve the surface mapping. This correction pipeline is also applied to ISS images. Our interpretative geological map shows that the lake is surrounded mostly by flat plains, except in the North where mountains are present (rough areas with dendritic valleys and triangular facets in the SAR images). The typical radar-dark signature of liquids is present over half the surface area of the lake only. Channels draining the plains SW of Ontario Lacus can be followed on

  8. Imaging magnetographs for high-resolution solar observations in the visible and near-infrared wavelength region

    NASA Astrophysics Data System (ADS)

    Denker, C.; Didkovsky, L.; Ma, J.; Shumko, S.; Varsik, J.; Wang, J.; Wang, H.; Goode, P. R.

    The Coudé feed of the vacuum telescope (aperture D=65 cm) at the Big Bear Solar Observatory (BBSO) is currently completely remodelled to accommodate a correlation tracker and a high-order Adaptive Optics (AO) system. The AO system serves two imaging magnetograph systems located at a new optical laboratory on the observatory's 2nd floor. The InfraRed Imaging Magnetograph (IRIM) is an innovative magnetograph system for near-infrared (NIR) observations in the wavelength region from 1.0 mu m to 1.6 mu m. The Visible-light Imaging Magnetograph (VIM) is basically a twin of IRIM for observations in the wavelength range from 550 nm to 700 nm. Both instruments were designed for high spatial and high temporal observations of the solar photosphere and chromosphere. Real-time data processing is an integral part of the instruments and will enhance BBSO's capabilities in monitoring solar activity and predicting and forecasting space weather.

  9. Search for and limits on plume activity on Mimas, Tethys, and Dione with the Cassini Visual Infrared Mapping Spectrometer (VIMS)

    USGS Publications Warehouse

    Buratti, B.J.; Faulk, S.P.; Mosher, J.; Baines, K.H.; Brown, R.H.; Clark, R.N.; Nicholson, P.D.

    2011-01-01

    Cassini Visual Infrared Mapping Spectrometer (VIMS) observations of Mimas, Tethys, and Dione obtained during the nominal and extended missions at large solar phase angles were analyzed to search for plume activity. No forward scattered peaks in the solar phase curves of these satellites were detected. The upper limit on water vapor production for Mimas and Tethys is one order of magnitude less than the production for Enceladus. For Dione, the upper limit is two orders of magnitude less, suggesting this world is as inert as Rhea (Pitman, K.M., Buratti, B.J., Mosher, J.A., Bauer, J.M., Momary, T., Brown, R.H., Nicholson, P.D., Hedman, M.M. [2008]. Astrophys. J. Lett. 680, L65-L68). Although the plumes are best seen at ???2.0. ??m, Imaging Science Subsystem (ISS) Narrow Angle Camera images obtained at the same time as the VIMS data were also inspected for these features. None of the Cassini ISS images shows evidence for plumes. The absence of evidence for any Enceladus-like plumes on the medium-sized saturnian satellites cannot absolutely rule out current geologic activity. The activity may below our threshold of detection, or it may be occurring but not captured on the handful of observations at large solar phase angles obtained for each moon. Many VIMS and ISS images of Enceladus at large solar phase angles, for example, do not contain plumes, as the active "tiger stripes" in the south pole region are pointed away from the spacecraft at these times. The 7-year Cassini Solstice Mission is scheduled to gather additional measurements at large solar phase angles that are capable of revealing activity on the saturnian moons. ?? 2011 Elsevier Inc.

  10. A RT-based Technique for the Analysis and the Removal of Titan's Atmosphere by Cassini/VIMS-IR data

    NASA Astrophysics Data System (ADS)

    Sindoni, G.; Tosi, F.; Adriani, A.; Moriconi, M. L.; D'Aversa, E.; Grassi, D.; Oliva, F.; Dinelli, B. M.; Castelli, E.

    2015-12-01

    Since 2004, the Visual and Infrared Mapping Spectrometer (VIMS), together with the CIRS and UVIS spectrometers, aboard the Cassini spacecraft has provided insight on Saturn and Titan atmospheres through remote sensing observations. The presence of clouds and aerosols in Titan's dense atmosphere makes the analysis of the surface radiation a difficult task. For this purpose, an atmospheric radiative transfer (RT) model is required. The implementation of a RT code, which includes multiple scattering, in an inversion algorithm based on the Bayesian approach, can provide strong constraints about both the surface albedo and the atmospheric composition. The application of this retrieval procedure we have developed to VIMS-IR spectra acquired in nadir or slant geometries allows us to retrieve the equivalent opacity of Titan's atmosphere in terms of variable aerosols and gaseous content. Thus, the separation of the atmospheric and surface contributions in the observed spectrum is possible. The atmospheric removal procedure was tested on the spectral range 1-2.2μm of publicly available VIMS data covering the Ontario Lacus and Ligeia Mare regions. The retrieval of the accurate composition of Titan's atmosphere is a much more complex task. So far, the information about the vertical structure of the atmosphere by limb spectra was mostly derived under conditions where the scattering could be neglected [1,2]. Indeed, since the very high aerosol load in the middle-low atmosphere produces strong scattering effects on the measured spectra, the analysis requires a RT modeling taking into account multiple scattering in a spherical-shell geometry. Therefore the use of an innovative method we are developing based on the Monte-Carlo approach, can provide important information about the vertical distribution of the aerosols and the gases composing Titan's atmosphere.[1]Bellucci et al., (2009). Icarus, 201, Issue 1, p. 198-216.[2]de Kok et al., (2007). Icarus, 191, Issue 1, p. 223-235.

  11. Insights on the structural characteristics of Vim-TBS (58-81) peptide for future applications as a cell penetrating peptide.

    PubMed

    Saini, Avneet; Jaswal, Radhika R; Negi, Riteshwari; Nandel, Fateh S

    2013-10-01

    The plasma membrane presents a remarkable barrier for the delivery of peptide and nucleic acid based drugs to the inside of cells. This restraint in the path of their development as therapeutic agents can be offset by their conjugation to cell penetrating peptides (CPPs) that can lead to an improved pharmacological profile. In this context, conformational behavior of Vimentin Tubulin Binding Site (TBS) peptide, Vim-TBS (58-81), was investigated for its acknowledged cell penetrating properties along with Trans-activating Tat (48-60) peptide and a pro-apoptogenic peptide of p21/WAFI protein (p10). Also, the fusion peptides Vim- TBS (58-81)-p10 & Tat (48-60)-p10 were studied using molecular mechanics (MM) and molecular dynamics (MD) based strategies. MM results revealed formation of stable α-helix like secondary structures in Vim-TBS (58-81), Tat (48-60) and p10 peptides. In water, three peptides adopted either a helical structure or a random conformation; the stability of either of the two states being governed by the formation of polar contacts with the solvent. The fusion peptides formed helical structures after MD simulations but the structure obtained for the fusion peptide, Vim-TBS-p10 is relatively better characterized in terms of its amphipathic nature with a hydrophilic face formed by the positively charged residues facilitating a better interaction of this fusion peptide with the membrane as compared to that of Tat-p10 peptide. This is the first report on the conformational characteristics of the Vim-TBS (58-81) peptide and the fusion peptide, Vim-TBS (58-81)-p10. The results presented here are significant for their potential role in guiding and facilitating the future efforts of designing peptide based cell penetrating drugs.

  12. Antibiotic resistance pattern and evaluation of metallo-beta lactamase genes (VIM and IMP) in Pseudomonas aeruginosa strains producing MBL enzyme, isolated from patients with secondary immunodeficiency

    PubMed Central

    Shirani, Kiana; Ataei, Behrouz; Roshandel, Fardad

    2016-01-01

    Background: One of the most common causes of hospital-acquired secondary infections in hospitalized patients is Pseudomonas aeruginosa. The aim of this study is to evaluate the expression of IMP and VIM in Pseudomonas aeruginosa strains (carbapenem resistant and producer MBL enzyme) in patients with secondary immunodeficiency. Materials and Methods: In a cross sectional study, 96 patients with secondary immunodeficiency hospitalized in the Al-Zahra hospital were selected. Carbapenem resistant strains isolated and modified Hodge test was performed in order to confirm the presence of the metallo carbapenemase enzyme. Under the standard conditions they were sent to the central laboratory for investigating nosocomial infection Multiplex PCR. Results: Of 96 samples 28.1% were IMP positive, 5.2% VIM positive and 3.1% both VIM and IMP positive. The prevalence of multidrug resistance in the IMP and/or VIM negative samples was 29%, while all 5 VIM positive samples have had multidrug resistance. Also the prevalence of multi-drug resistance in IMP positive samples were 96.3% and in IMP and VIM positive samples were 100%. According to Fisher’s test, the prevalence of multi-drug resistance based on gene expression has significant difference (P < 0.001). Conclusion: Based on the results of this study it can be concluded that, a significant percentage of patients with secondary immunodeficiency that suffer nosocomial infections with multidrug resistance, especially Pseudomonas aeruginosa, are probably MBL-producing gene positive. Therefore the cause of infection should be considered in the hospital care system to identify their features, the presence of genes involved in the development of multi-drug resistance and antibiotic therapy. PMID:27563634

  13. Scale

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2009-01-01

    The common approach to scaling, according to Christopher Dede, a professor of learning technologies at the Harvard Graduate School of Education, is to jump in and say, "Let's go out and find more money, recruit more participants, hire more people. Let's just keep doing the same thing, bigger and bigger." That, he observes, "tends to fail, and fail…

  14. Wavelength meter having elliptical wedge

    DOEpatents

    Hackel, R.P.; Feldman, M.

    1992-12-01

    A wavelength meter is disclosed which can determine the wavelength of a laser beam from a laser source within an accuracy range of two parts in 10[sup 8]. The wavelength meter has wedge having an elliptically shaped face to the optical path of the laser source and includes interferometer plates which form a vacuum housing. 7 figs.

  15. Wavelength meter having elliptical wedge

    DOEpatents

    Hackel, Richard P.; Feldman, Mark

    1992-01-01

    A wavelength meter is disclosed which can determine the wavelength of a laser beam from a laser source within an accuracy range of two parts in 10.sup.8. The wavelength meter has wedge having an elliptically shaped face to the optical path of the laser source and includes interferometer plates which form a vacuum housing.

  16. CASSINI/altimeter and VIMS complementarity: example using observations over the same area from Ta and T13 Titan's flybys

    NASA Astrophysics Data System (ADS)

    Crapeau, M.; Rodriguez, S.; Le Mouelic, S.; Paillou, Ph.; Sotin, C.; Wall, S.

    The altimeter mode of the Ku-band RADAR experiment onboard the Cassini-Huygens mission has been designed primarily for the study of Titan's surface topography. Inspired by what is done on the Earth in icy contexts like in the Antarctic, Cassini altimetry data can also be used to retrieve the radar reflectivity of Titan's surface and thus, information about its nature. Our first study shows clear contrasts of the radar reflectivity along the altimeter track acquired during the first Titan flyby (Ta). This distinct decrease in radar reflectivity is somewhat correlated with a slight surface height variation. The 13th Titan flyby (T13) provided us VIMS (Visual and Infrared Mapping Spectrometer, operating between 0.3 and 5.1 µm) medium resolution observations of the same region. Infrared I/F along the Ta altimeter track presents a very strong correlation with the computed radar reflectivity. These correlations between infrared I/F and radar reflectivity variations indicate a change in the surface nature and the presence of a clearly defined surface structure under the track. VIMS 2.03/1.27 µm channels ratio transect along the altimeter track also suggests a local enrichment in water ice associated with a smooth depression, maybe witnessing ancient channels.

  17. Cassini/Altimeter and Vims Complementarity: Example Using Observations Over the Same Area From Ta and T13 Titan's Flybys

    NASA Astrophysics Data System (ADS)

    Crapeau, Marc; Rodriguez, S.; Le Mouelic, S.; Paillou, P.; Sotin, C.; Wall, S. D.; VIMS science Team; RADAR science Team

    2006-09-01

    The altimeter mode of the Ku-band RADAR experiment onboard the Cassini-Huygens mission has been designed primarily for the study of Titan's surface topography. Inspired by what is done on the Earth in icy contexts like in the Antarctic, Cassini altimetry data can also be used to retrieve the radar reflectivity of Titan's surface and thus, information about its nature. Our first study shows clear contrasts of the radar reflectivity along the altimeter track acquired during the first Titan flyby (Ta). This distinct decrease in radar reflectivity is somewhat correlated with a slight surface height variation. The 13th Titan flyby (T13) provided us VIMS (Visual and Infrared Mapping Spectrometer, operating between 0.3 and 5.1 µm) medium resolution observations of the same region. Infrared I/F along the Ta altimeter track presents a very strong correlation with the computed radar reflectivity. These correlations between infrared I/F and radar reflectivity variations indicate a change in the surface nature and the presence of a clearly defined surface structure under the track. VIMS 2.03/1.27 µm channels ratio transect along the altimeter track also suggests a local enrichment in water ice associated with a smooth depression, maybe witnessing ancient channels.

  18. Titan's mid-latitude surface regions with Cassini VIMS and SAR

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Drossart, Pierre; Brown, Robert H.; Sohl, Frank; Stephan, Katrin; Jaumann, Ralf; Rodriguez, Sebastien; Bratsolis, Emmanuel; Schmitt, Bernard; Le Gall, Alice; Lopes, Rosaly; Malaska, Michael; Janssen, Michael; Maltagliati, Luca; Villanueva, Edward; Matsoukas, Christos

    2016-07-01

    We investigate the surface of Saturn's moon Titan by means of two Cassini instruments used in synergy. We apply a radiative transfer code to VIMS hyperspectral data to correct the strong atmospheric contribution and extract information on surface composition (Hirtzig et al. 2014; Solomonidou et al. 2014; 2015). We then put this in the context of terrain morphology by use of denoised Synthetic Aperture Radar (SAR) images (Bratsolis et al. 2012). We examine here the mid-latitude zones extending from 50ºN to 50ºS, which includes key geological features identified in Lopes et al. (2010, 2015) and Malaska et al. (2015): mountains, plains, labyrinths, dune fields, and possible cryovolcanic and/or evaporitic deposits. We find that many of the different units show compositional variations while units of significant geomorphological differences seem to consist of very similar material mixtures. The Huygens landing site and the candidate evaporitic regions are compositionally similar to the variable plains. We also find that temporal variations of surface albedo exist for two of the candidate cryovolcanic regions Tui Regio and Sotra Patera, suggesting the presence of surface activity, while a number of other regions such as Hotei Regio and the undifferentiated plains remain unchanged (Solomonidou et al. 2015). The surface albedo variations, together with the presence of volcanic-like morphological features, suggest that the active regions are possibly related to the deep interior, possibly via cryovolcanic processes (with important implications for the satellite's astrobiological potential) as also indicated by recent interior structure models of Titan and corresponding calculations of the spatial pattern of maximum tidal stresses (Sohl et al. 2014). In previous studies (Lopes et al. 2015; Solomonidou et al. 2015) we showed that a variety of surface processes could be linked to the formation of the various geomorphological units (aeolian, fluvial, sedimentary, lacustrine

  19. Titan’s mid-latitude surface regions with Cassini VIMS and RADAR

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Lopes, Rosaly M. C.; Coustenis, Athena; Malaska, Michael; Rodriguez, Sebastien; Maltagliati, Luca; Drossart, Pierre; Janssen, Michael; Lawrence, Kenneth; Jaumann, Ralf; Sohl, Frank; Stephan, Katrin; Brown, Robert H.; Bratsolis, Emmanuel; Matsoukas, Christos

    2015-11-01

    The Cassini-Huygens mission instruments have revealed Titan to have a complex and dynamic atmosphere and surface. Data from the remote sensing instruments have shown the presence of diverse surface terrains in terms of morphology and composition, suggesting both exogenic and endogenic processes [1]. We define both the surface and atmospheric contributions in the VIMS spectro-imaging data by use of a radiative transfer code in the near-IR range [2]. To complement this dataset, the Cassini RADAR instrument provides additional information on the surface morphology, from which valuable geological interpretations can be obtained [3]. We examine the origin of key Titan terrains, covering the mid-latitude zones extending from 50ºN to 50ºS. The different geological terrains we investigate include: mountains, plains, labyrinths, craters, dune fields, and possible cryovolcanic and/or evaporite features. We have found that the labyrinth terrains and the undifferentiated plains seem to consist of a very similar if not the same material, while the different types of plains show compositional variations [3]. The processes most likely linked to their formation are aeolian, fluvial, sedimentary, lacustrine, in addition to the deposition of atmospheric products though the process of photolysis and sedimentation of organics. We show that temporal variations of surface albedo exist for two of the candidate cryovolcanic regions. The surface albedo variations together with the presence of volcanic-like morphological features suggest that the active regions are possibly related to the deep interior, possibly via cryovolcanism processes (with important implications for the satellite’s astrobiological potential) as also indicated by new interior structure models of Titan and corresponding calculations of the spatial pattern of maximum tidal stresses [4]. However, an explanation attributed to exogenic processes is also possible [5]. We will report on results from our most recent

  20. Cassini VIMS and RADAR investigation of Titan's equatorial regions: a case for changes in surface properties

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Lopes, Rosaly M. C.; Rodriguez, Sebastien; Hirtzig, Mathieu; Malaska, Michael; Stephan, Katrin; Sotin, Christophe; Drossart, Pierre; Jaumann, Ralf; Bratsolis, Emmanuel; Le Mouélic, Stephane; Brown, Robert H.

    2015-04-01

    The Cassini-Huygens instruments revealed that Titan, Saturn's largest moon, has - in many aspects - a complex, dynamic and Earth-like surface [1;2;3]. Understanding the distribution and interplay of geologic processes on Titan is important for constraining models of its interior, surface-atmosphere interactions, and climate evolution. Data from the remote sensing instruments have shown the presence of diverse terrains, suggesting exogenic and endogenic processes, whose composition remains largely unknown. Interpreting surface features further requires precise knowledge of the contribution by the dense intervening atmosphere, especially the troposphere, which can be recovered from near-IR data such as those collected by Cassini's Visual and Infrared Mapping Spectrometer (VIMS) collects in the so-called "methane windows". In order to simulate the atmospheric contribution and extract surface information, a statistical tool (PCA) and a radiative transfer code are applied on certain regions of interest (i.e. possibly geologically varying and suggested in some cases to be cryovolcanic and/or evaporitic in origin) [4;5;7]. We also analyze RADAR despeckled SAR images in terms of morphology [6]. For comparison, we also look at undifferentiated plains and dune fields regions that are not expected to change with time. We find that Tui Regio and Sotra Patera change with time becoming darker and brighter respectively in terms of surface albedo while the plains and the suggested evaporitic areas in the equatorial regions do not present any significant change [5]. The surface brightening of Sotra supports a possible internal rather than exogenic origin. The unchanged surface behavior of the plains supports a sedimentary origin rather than cryovolcanic. Preliminary results on the chemical composition of the changed regions with time are also presented. We therefore suggest that temporal variations of surface albedo (in chemical composition and/or morphology) exist for some areas

  1. Constraints on the nature of various Titan Geomorphological Units with Cassini/VIMS and SAR

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Lopes, Rosaly M. C.; Rodriguez, Sébastien; Schmitt, Bernard; Philippe, Sylvain; Malaska, Michael; Lawrence, Kenneth J.; Janssen, Michael A.; Le Gall, Alice; Jaumann, Ralf; Sohl, Frank; Stephan, Katrin; Drossart, Pierre; Brown, Robert H.; Maltagliati, Luca; Bratsolis, Emmanuel; Matsoukas, Christos

    2016-10-01

    We investigate the lower atmosphere of Titan from Visual and Infrared Mapping Spectrometer (VIMS) spectro-imaging data by use of a recently updated radiative transfer code in the near-IR range and RADAR/SAR data for the distinction of geomorphological units. We focus here on the geological major units identified in [1;2] and [3]: mountains, plains, labyrinths, dune fields, and possible cryovolcanic and/or evaporitic features (the latter two are albedo features, [4;5;6]). We infer surface properties (like absolute surface albedo and morphology) and atmospheric contributions, in particular the haze content. We find that the Huygens landing site and the candidate evaporitic regions pair compositionally with the variable plains, thus indicating that units of significant geomorphological differences seem to consist of very similar materials. Similarly for the labyrinth terrains and the undifferentiated plains. On the contrary, many regions from the same geomorphological unit show compositional variations depending on location (i.e. undifferentiated plains). These differences provide implications on the endogenic or exogenic origin of the various units. In previous studies we showed that the processes most likely linked to the formation of the various geomorphological units are aeolian, fluvial, sedimentary, and lacustrine, in addition to the deposition of organics through the atmosphere. Currently, we are working on deriving information on the chemical composition of the aforementioned regions from the extracted surface albedos using an extensive library of ices and tholins [e.g. 7]. This will shed light on the potential formation processes (Solomonidou et al. in prep.). Preliminary results on the chemical composition of the regions that have shown temporal changes (i.e. Tui Regio and Sotra Patera; [6]) are also presented.References: [1] Lopes, R.M.C., et al.: Icarus, 205, 540-558, 2010; [2] Lopes, R.M.C., et al.: Icarus, 270, 162-182, 2016; [3] Malaska, M., et al

  2. Quadrature wavelength scanning interferometry.

    PubMed

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-07-10

    A novel method to double the measurement range of wavelength scanning interferometery (WSI) is described. In WSI the measured optical path difference (OPD) is affected by a sign ambiguity, that is, from an interference signal it is not possible to distinguish whether the OPD is positive or negative. The sign ambiguity can be resolved by measuring an interference signal in quadrature. A method to obtain a quadrature interference signal for WSI is described, and a theoretical analysis of the advantages is reported. Simulations of the advantages of the technique and of signal errors due to nonideal quadrature are discussed. The analysis and simulation are supported by experimental measurements to show the improved performances. PMID:27409307

  3. Comets at radio wavelengths

    NASA Astrophysics Data System (ADS)

    Crovisier, Jacques; Bockelée-Morvan, Dominique; Colom, Pierre; Biver, Nicolas

    2016-11-01

    Comets are considered as the most primitive objects in the Solar System. Their composition provides information on the composition of the primitive solar nebula, 4.6 Gyr ago. The radio domain is a privileged tool to study the composition of cometary ices. Observations of the OH radical at 18 cm wavelength allow us to measure the water production rate. A wealth of molecules (and some of their isotopologues) coming from the sublimation of ices in the nucleus have been identified by observations in the millimetre and submillimetre domains. We present an historical review on radio observations of comets, focusing on the results from our group, and including recent observations with the Nançay radio telescope, the IRAM antennas, the Odin satellite, the Herschel space observatory, ALMA, and the MIRO instrument aboard the Rosetta space probe. xml:lang="fr"

  4. Picosecond Surface Acoustic Waves Using A Suboptical Wavelength Absorption Grating

    SciTech Connect

    Hurley, David Howard; Telschow, Kenneth Louis

    2002-10-01

    We have demonstrated laser generation and detection of Rayleigh surface acoustic waves (SAW’s) with acoustic wavelengths that are smaller than the optical wavelength of both the excitation and the detection beams. SAW generation was achieved using electron beam lithography to modulate the surface reflectivity and hence the lateral thermal gradients on a suboptical wavelength scale. The generation and detection characteristics of two material systems were investigated (aluminum absorption gratings on Si and GaAs substrates). The polarization sensitive absorption characteristics of the suboptical wavelength lithographic grating were exploited in order to explore various acoustic generation and detection schemes.

  5. Scales

    SciTech Connect

    Murray Gibson

    2007-04-27

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  6. Scales

    ScienceCinema

    Murray Gibson

    2016-07-12

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  7. Diffraction cancellation over multiple wavelengths in photorefractive dipolar glasses.

    PubMed

    Parravicini, J; Di Mei, F; Conti, C; Agranat, A J; DelRe, E

    2011-11-21

    We report the simultaneous diffraction cancellation for beams of different wavelengths in out-of-equilibrium dipolar glass. The effect is supported by the photorefractive diffusive nonlinearity and scale-free optics, and can find application in imaging and microscopy.

  8. Galilean Satellite Surface Non-Ice Constituents: New Results from the Cassini/Huygens VIMS Jupiter Flyby in the Context of the Galileo NIMS Results

    NASA Technical Reports Server (NTRS)

    McCord, T. B.; Brown, R.; Baines, K.; Bellucci, G.; Bibring, J.-P.; Buratti, B.; Capaccioni, F.; Cerroni, P.; Clark, R.; Coradini, A.

    2001-01-01

    The Cassini mission Visible and Infrared Mapping Spectrometer (VIMS) is currently returning data for the Galilean satellites. Examples of the new satellite data and the initial interpretations will be presented in the context of the Galileo NIMS data and results. Additional information is contained in the original extended abstract.

  9. Internal to external wavelength calibration

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash C.

    1999-01-01

    The spectra of Hen 1357 (the Stingray nebula) were used to check the internal to external wavelength calibration of the STIS first order CCD modes. The radial velocity of the Stingray nebula is known to high accuracy (< 1 km/sec) and the line with of the nebular line is very narrow (< 8 km/sec for the integrated nebula). Thus the observations of the Stingray nebula are ideal to check the internal to external wavelength calibration of the first order modes. The observations were taken in G430L and G750M modes using a 52 x 0.05 arcsec slit covering the wavelength range 2900 to 5700 A and 6295 to 6867 A, respectively. The observed wavelength range includes many nebular emission lines. The wavelengths of the nebular lines derived using the pipeline internal wavelength calibration were compared with the wavelengths derived from other ground based observations. In all cases, the wavelength match between the two is of the same order as the accuracy to which the line center can be measured. These results imply that there is no significant offset between the internal and external wavelength calibrations for these modes. The HDF-S QSO observations were also used for this test both for the first order and the Echelle modes. The results of the HDF-S QSO observations further confirm the above finding for the first order modes, and imply that there is no significant offset between the internal and external wavelength calibration for the Echelle modes.

  10. Wavelength-conserving grating router for intermediate wavelength density

    DOEpatents

    Deri, Robert J.; Patel, Rajesh R.; Bond, Steven W.; Bennett, Cory V.

    2007-03-20

    A wavelength router to be used for fiber optical networking router is based on a diffraction grating which utilizes only N wavelengths to interconnect N inputs to N outputs. The basic approach is to augment the grating with additional couplers or wavelength selective elements so than N-1 of the 2N-1 outputs are combined with other N outputs (leaving only N outputs). One embodiment uses directional couplers as combiners. Another embodiment uses wavelength-selective couplers. Another embodiment uses a pair of diffraction gratings to maintain parallel propagation of all optical beams. Also, beam combining can be implemented either by using retroflection back through the grating pair or by using couplers.

  11. Saturn’s icy satellites investigated by Cassini-VIMS. II. Results at the end of nominal mission

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Clark, R. N.; Cuzzi, J. N.; Cruikshank, D. P.; Coradini, A.; Cerroni, P.; Nicholson, P. D.; McCord, T. B.; Brown, R. H.; Buratti, B. J.; Tosi, F.; Nelson, R. M.; Jaumann, R.; Stephan, K.

    2010-04-01

    We report the detailed analysis of the spectrophotometric properties of Saturn's icy satellites as derived by full-disk observations obtained by visual and infrared mapping spectrometer (VIMS) experiment aboard Cassini. In this paper, we have extended the coverage until the end of the Cassini's nominal mission (June 1st 2008), while a previous paper ( Filacchione, G., and 28 colleagues [2007]. Icarus 186, 259-290, hereby referred to as Paper I) reported the preliminary results of this study. During the four years of nominal mission, VIMS has observed the entire population of Saturn's icy satellites allowing us to make a comparative analysis of the VIS-NIR spectral properties of the major satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Hyperion, Iapetus) and irregular moons (Atlas, Prometheus, Pandora, Janus, Epimetheus, Telesto, Calypso, Phoebe). The results we discuss here are derived from the entire dataset available at June 2008 which consists of 1417 full-disk observations acquired from a variety of distances and inclinations from the equatorial plane, with different phase angles and hemispheric coverage. The most important spectrophotometric indicators (as defined in Paper I: I/ F continua at 0.55 μm, 1.822 μm and 3.547 μm, visible spectral slopes, water and carbon dioxide bands depths and positions) are calculated for each observation in order to investigate the disk-integrated composition of the satellites, the distribution of water ice respect to "contaminants" abundances and typical regolith grain properties. These quantities vary from the almost pure water ice surfaces of Enceladus and Calypso to the organic and carbon dioxide rich Hyperion, Iapetus and Phoebe. Janus visible colors are intermediate between these two classes having a slightly positive spectral slope. These results could help to decipher the origins and evolutionary history of the minor moons of the Saturn's system. We introduce a polar representation of the spectrophotometric

  12. Molecular detection of metallo-β-lactamase gene blaVIM-1 in imipenem-resistant Pseudomonas aeruginosa strains isolated from hospitalized patients in the hospitals of Isfahan

    PubMed Central

    Sedighi, Mansour; Vaez, Hamid; Moghoofeie, Mohsen; Hadifar, Shima; Oryan, Golfam; Faghri, Jamshid

    2015-01-01

    Background: Pseudomonas aeruginosa is an opportunistic human pathogen that causes serious problems, especially in people, who have immunodeficiency. In recent times, metallo-β-lactamase (MBLs) resistance in this bacterium has led to some difficulties in treating bacterial infections. The metallo-beta-lactamase family of genes, including blaVIM-1, is being reported with increasing frequency worldwide. The aim of this study is the detection of the metallo-β-lactamase gene blaVIM-1 in imipenem-resistant P. aeruginosa (IRPA) strains isolated from hospitalized patients. Materials and Methods: In this study, 106 P. aeruginosa samples were isolated from various nosocomial infections. The isolates were identified, tested for susceptibility to various antimicrobial agents by the Kirby-Bauer disk diffusion method, and all the imipenem-resistant isolates were screened for the presence of MBLs by using the combined disk (IMP-EDTA). The minimal inhibitory concentration (MIC) of imipenem was determined by E-test on the Mueller-Hinton agar. To detect the blaVIM-1 gene, the isolates were subjected to a polymerase chain reaction (PCR). Results: Of all the P. aeruginosa isolates, 62 (58.5%) were found to be imipenem-resistant P. aeruginosa (MIC ≥32 μg/ml). Twenty-six (42%) of the imipenem-resistant isolates were MBL positive. None of these isolates carried the blaVIM-1 gene using the PCR assay. Conclusion: The results demonstrated the serious therapeutic threat of the MBL-producing P. aeruginosa populations. The rate of imipenem resistance due to MBL was increased dramatically. Early detection and infection-control practices are the best antimicrobial strategies for this organism. None of MBL-producing isolates in this study carry the blaVIM-1 gene; therefore, another gene in the MBL family should be investigated. PMID:25802826

  13. Fragment-based discovery of inhibitor scaffolds targeting the metallo-β-lactamases NDM-1 and VIM-2.

    PubMed

    Christopeit, Tony; Leiros, Hanna-Kirsti S

    2016-04-15

    Metallo-β-lactamases (MBLs) render bacteria resistant to β-lactam antibiotics and are interesting drug targets to prevent the hydrolysis of β-lactam antibiotics. So far, there are no MBL inhibitors in clinical use and particularly the design of broad spectrum inhibitors targeting several MBLs has been difficult. In this study, we report four fragments inhibiting the clinically relevant New Delhi metallo-β-lactamase 1 (NDM-1) and Verona integron-encoded metallo-β-lactamase 2 (VIM-2). The fragments were identified from a library using an orthogonal screening strategy combining a surface plasmon resonance (SPR) based assay and an enzyme inhibition assay. The identified fragments showed dissociation constants (KD) ranging from 181 to 2100 μM. The binding mode of the fragments was explored using QM-polarized ligand docking. All four fragments represent interesting scaffolds for the design of broad-spectrum MBL inhibitors. PMID:26976213

  14. Additive-Subtractive Two-Wavelength ESPI Contouring by Using a Synthetic Wavelength Phase Shift.

    PubMed

    Hack, E; Frei, B; Kästle, R; Sennhauser, U

    1998-05-01

    The addition correlation of two speckle fields by simultaneousillumination at different wavelengths is used for object contouring ina Twyman-Green-type interferometer. Fringe visibility is enhancedwhen the stochastic speckle background intensity obtained from areference plane modulation is subtracted. We calculate the contourphase map by using a phase-shift algorithm in the syntheticwavelength. A comparison with a sequential illumination, phasedifference method based on a laser wavelength phase shift isgiven. The test setup does not need to be stable on aninterferometric scale, and therefore a method is provided that lendsitself to applications in noisy environments.

  15. Laser wavelength comparison by high resolution interferometry.

    PubMed

    Layer, H P; Deslattes, R D; Schweitzer, W G

    1976-03-01

    High resolution interferometry has been used to determine the wavelength ratio between two molecularly stabilized He-Ne lasers, one locked to a methane absorption at 3.39 microm and the other locked to the k peak of (129)I(2) at 633 nm. An optical beat frequency technique gave fractional orders while a microwave sideband method yielded the integer parts. Conventional (third derivative) peak seeking servoes stabilized both laser and cavity lengths. Reproducibility of the electronic control system and optics was a few parts in 10(12), while systematic errors associated with curvature of the cavity mirrors limited the accuracy of the wavelength ratio measurement to 2 parts in 10(10). The measured wavelength ratio of the methane stabilized He-Ne laser at 3.39 microm [P(7) line, nu(3) band] to the (129)I(2) (k peak) stabilized He-Ne laser at 633 nm was 5.359 049 260 6 (0.000 2 ppm). This ratio agrees with that calculated from the (lower accuracy) results of earlier wavelength measurements made relative to the (86)Kr standard. Its higher accuracy thus permits a provisional extension of the frequency scale based on the cesium oscillator into the visible spectrum.

  16. Clouds and hazes vertical structure mapping of Saturn 2011 - 2012 giant vortex by means of Cassini VIMS data analysis.

    NASA Astrophysics Data System (ADS)

    Oliva, F.; Adriani, A.; Moriconi, M. L.; Liberti, G. L.; D'Aversa, E.

    On December 2010 a giant storm erupted in Saturn's North hemisphere. A giant vortex formed in the storm wake and persisted after the principal outburst exhausted on July 2011. The vortex had been imaged several times by the Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini probe starting from May 2011 and it was still present in observations recorded on June 2013. In this work we have analyzed the vortex data recorded by the visual channel of the spectrometer (VIMS-V) in August 2011 and January 2012. An inverse model, based on the Bayesian approach and using the Gauss-Newton iterative method to minimize the cost function, has been developed to analyze those data. The model takes advantage of the results of a supporting forward radiative transfer model which relies on the assumptions of plane parallel atmosphere, multiple scattering, Mie theory to compute particles single scattering properties, and molecular scattering adapted to Saturn's atmosphere. Applying the inverse model we could retrieve the microphysical and geometrical properties of the clouds and hazes overlying the vortex and produce spatial maps for each retrieved parameter. Thanks to this study, the vertical structure of the hazes in this region has been quantitatively addressed for the first time. The comparative analysis of the results from the two observations seems to suggest that in 6 months the atmospheric dynamics, responsible for the formation and subsistence of the vortex, is weakening and the atmosphere is returning to a more stationary state. In addition, we suggest a correction for the imaginary part of the refractive index of the tropopause haze. This new value, that allows a better convergence between observed and simulated spectra, does not yet identify a composition of the haze and further investigation is needed to understand the real nature of the need for such a modification.

  17. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/Vims

    USGS Publications Warehouse

    Baines, K.H.; Momary, T.W.; Buratti, B.J.; Matson, D.L.; Nelson, R.M.; Drossart, P.; Sicardy, B.; Formisano, V.; Bellucci, G.; Coradini, A.; Griffith, C.; Brown, R.H.; Bibring, J.-P.; Langevin, Y.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Combes, M.; Cruikshank, D.P.; Jaumann, R.; McCordt, T.B.; Mennella, V.; Nicholson, P.D.; Sotin, C.

    2006-01-01

    The wide spectral coverage and extensive spatial, temporal, and phase-angle mapping capabilities of the Visual Infrared Mapping Spectrometer (VIMS) onboard the Cassini-Huygens Orbiter are producing fundamental new insights into the nature of the atmospheres of Saturn and Titan. For both bodies, VIMS maps over time and solar phase angles provide information for a multitude of atmospheric constituents and aerosol layers, providing new insights into atmospheric structure and dynamical and chemical processes. For Saturn, salient early results include evidence for phosphine depletion in relatively dark and less cloudy belts at temperate and mid-latitudes compared to the relatively bright and cloudier Equatorial Region, consistent with traditional theories of belts being regions of relative downwelling. Additional Saturn results include (1) the mapping of enhanced trace gas absorptions at the south pole, and (2) the first high phase-angle, high-spatial-resolution imagery of CH4 fluorescence. An additional fundamental new result is the first nighttime near-infrared mapping of Saturn, clearly showing discrete meteorological features relatively deep in the atmosphere beneath the planet's sunlit haze and cloud layers, thus revealing a new dynamical regime at depth where vertical dynamics is relatively more important than zonal dynamics in determining cloud morphology. Zonal wind measurements at deeper levels than previously available are achieved by tracking these features over multiple days, thereby providing measurements of zonal wind shears within Saturn's troposphere when compared to cloudtop movements measured in reflected sunlight. For Titan, initial results include (1) the first detection and mapping of thermal emission spectra of CO, CO2, and CH3D on Titan's nightside limb, (2) the mapping of CH4 fluorescence over the dayside bright limb, extending to ??? 750 km altitude, (3) wind measurements of ???0.5 ms-1, favoring prograde, from the movement of a persistent

  18. Not So Titanic Winds: Cassini/VIMS Observations of Cloud Features in the Southern Hemisphere of Titan

    NASA Astrophysics Data System (ADS)

    Momary, T. W.; Baines, K. H.; Buratti, B. J.; Griffith, C.; Brown, R. H.; Jaumann, R.; Drossart, P.; Cassini VIMS

    2004-11-01

    One atmospheric science objective of VIMS is to measure windspeeds of cloud features in the Saturnian system at known altitudes, as determined from the 352 spectral bands that VIMS provides. The Titan encounter of 2 July 2004 provided the first opportunity to measure cloud-tracked winds on Titan. Spectral imagery revealed that cloud coverage of Titan was sparse, covering less than 1.5% of the observed sunlit surface. Nevertheless several clouds were followed during the encounter. The most prominent cloud, comprising the bulk of the cloud coverage, was located near the South Pole ( 87 degrees south, 0 degrees lon) and was roughly circular with a diameter of 600 ± 110 km. We tracked this feature over 11 images spanning a 13 hour period. In an attempt to quantify movement of the clouds in a Titanian windstream, we navigated the clouds using three distinct methods: 1) by tracking the brightest pixel in each cloud feature and employing SPICE kernel derived geometry, 2) similarly, by tracking the centroid of the main cloud feature, and 3) for the first time for an outer solar system body, by tracking relative to surface features seen in atmospheric spectral windows, most notably at 2.02 microns. The variable brightness of the most prominent cloud feature and its proximity to the South Pole of Titan make it rather difficult to track accurately. However, preliminary results obtained by tracking the centroid of the main cloud feature, as well as by tracking relative to surface features, indicate that there is little movement over a period of 13 hours. Specifically, we measure a mean windspeed of 0.5 ± 3.3 m/s in the prograde direction.

  19. Interference comparator for laser diode wavelength and wavelength instability measurement.

    PubMed

    Dobosz, Marek; Kożuchowski, Mariusz

    2016-04-01

    Method and construction of a setup, which allows measuring the wavelength and wavelength instability of the light emitted by a laser diode (or a laser light source with a limited time coherence in general), is presented. The system is based on Twyman-Green interferometer configuration. Proportions of phases of the tested and reference laser's interference fringe obtained for a set optical path difference are a measure of the unknown wavelength. Optical path difference in interferometer is stabilized. The interferometric comparison is performed in vacuum chamber. The techniques of accurate fringe phase measurements are proposed. The obtained relative standard uncertainty of wavelength evaluation in the tested setup is about 2.5 ⋅ 10(-8). Uncertainty of wavelength instability measurement is an order of magnitude better. Measurement range of the current setup is from 500 nm to 650 nm. The proposed technique allows high accuracy wavelength measurement of middle or low coherence sources of light. In case of the enlarged and complex frequency distribution of the laser, the evaluated wavelength can act as the length master in interferometer for displacement measurement. PMID:27131662

  20. Interference comparator for laser diode wavelength and wavelength instability measurement

    NASA Astrophysics Data System (ADS)

    Dobosz, Marek; KoŻuchowski, Mariusz

    2016-04-01

    Method and construction of a setup, which allows measuring the wavelength and wavelength instability of the light emitted by a laser diode (or a laser light source with a limited time coherence in general), is presented. The system is based on Twyman-Green interferometer configuration. Proportions of phases of the tested and reference laser's interference fringe obtained for a set optical path difference are a measure of the unknown wavelength. Optical path difference in interferometer is stabilized. The interferometric comparison is performed in vacuum chamber. The techniques of accurate fringe phase measurements are proposed. The obtained relative standard uncertainty of wavelength evaluation in the tested setup is about 2.5 ṡ 10-8. Uncertainty of wavelength instability measurement is an order of magnitude better. Measurement range of the current setup is from 500 nm to 650 nm. The proposed technique allows high accuracy wavelength measurement of middle or low coherence sources of light. In case of the enlarged and complex frequency distribution of the laser, the evaluated wavelength can act as the length master in interferometer for displacement measurement.

  1. Long-wavelength microinstabilities in toroidal plasmas

    SciTech Connect

    Tang, W.W.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,{theta}) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities.

  2. Long-wavelength microinstabilities in toroidal plasmas

    SciTech Connect

    Tang, W.W.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,[theta]) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities.

  3. AWG Filter for Wavelength Interrogator

    NASA Technical Reports Server (NTRS)

    Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

    2015-01-01

    A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

  4. The vimentin-tubulin binding site peptide (Vim-TBS.58-81) crosses the plasma membrane and enters the nuclei of human glioma cells.

    PubMed

    Balzeau, Julien; Peterson, Alan; Eyer, Joel

    2012-02-14

    Cell-penetrating peptides (CPPs) can translocate through the plasma membrane and localize in different cell compartments providing a promising delivery system for peptides, proteins, nucleic acids, and other products. Here we describe features of a novel cell-penetrating peptide derived from the intermediate filament protein vimentin, called Vim-TBS.58-81. We show that it enters cells from a glioblastoma line via endocytosis where it distributes throughout the cytoplasm and nucleus. Moreover, when coupled to the pro-apoptogenic peptide P10, it localizes to the nucleus inhibiting cell proliferation. Thus, the Vim-TBS.58-81 peptide represents an effective vector for delivery of peptides and potentially a broad range of cargos to the nucleus.

  5. Klebsiella pneumoniae Isolate from a New York City Hospital Belonging to Sequence Type 258 and Carrying blaKPC-2 and blaVIM-4

    PubMed Central

    Deshpande, Lalitagauri M.; Mills, Janet C.; Jones, Ronald N.; Soave, Rosemary; Jenkins, Stephen G.; Schuetz, Audrey N.

    2016-01-01

    Among 69 of 139 (49.6%) carbapenem-nonsusceptible Enterobacteriaceae carrying blaKPC, 1 Klebsiella pneumoniae was also positive for blaVIM. The isolate belonged to sequence type 258 (ST258) and carried blaKPC-2 on a copy of Tn4401a and blaVIM-4 on a class 1 integron. Genes were located on distinct plasmids belonging to Inc types A/C and FII. Elevated expression of the efflux pump AcrAB-TolC (acrA, 15.3 times) and reduced expression of outer membrane protein genes ompK35 and ompK37 (0.16 and 0.081 times, respectively) associated with various amino acid alterations on OmpK37 were observed. The presence of two carbapenemases in ST258 K. pneumoniae is of great concern due to the ability of this organism to widely disseminate. PMID:26729504

  6. SWOC: Spectral Wavelength Optimization Code

    NASA Astrophysics Data System (ADS)

    Ruchti, G. R.

    2016-06-01

    SWOC (Spectral Wavelength Optimization Code) determines the wavelength ranges that provide the optimal amount of information to achieve the required science goals for a spectroscopic study. It computes a figure-of-merit for different spectral configurations using a user-defined list of spectral features, and, utilizing a set of flux-calibrated spectra, determines the spectral regions showing the largest differences among the spectra.

  7. Towards short wavelengths FELs workshop

    SciTech Connect

    Ben-Zvi, I.; Winick, H.

    1993-12-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  8. Nosocomial Outbreak of VIM-1-Producing Klebsiella pneumoniae Isolates of Multilocus Sequence Type 15: Molecular Basis, Clinical Risk Factors, and Outcome

    PubMed Central

    Sánchez-Romero, Isabel; Asensio, Ángel; Muñoz-Algarra, María; Isidoro, Beatriz; Vindel, Ana; Álvarez-Avello, José; Balandín-Moreno, Bárbara; Cuevas, Oscar; Fernández-Romero, Sara; Azañedo, Luisa; Sáez, David; Campos, José

    2012-01-01

    We study the epidemiology, molecular basis, clinical risk factors, and outcome involved in the clonal dissemination of VIM-1-producing Klebsiella pneumoniae isolates in the hospital setting. All patients infected/colonized by carbapenem-nonsusceptible K. pneumoniae (CNSKP) in 2009 were included. Molecular epidemiology was studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Antibiotic resistance genes were analyzed by PCR and sequencing. Plasmids were studied by PFGE with S1 nuclease digestion and for incompatibility group by a PCR-based replicon typing scheme. Risk factors associated with CNSKP colonization/infection were assessed by an observational case-control study. All 55 patients studied were infected (n = 28) or colonized (n = 27) by VIM-1-producing K. pneumoniae. All but one acquired isolates of a single clone (PFGE cluster 1 [C1], sequence type 15 [ST15]), while another clone (PFGE C2, ST340) was detected in four patients. C1 isolates also produced the new extended-spectrum β-lactamase SHV-134. blaVIM-1 was carried in a class 1 integron and an untypeable plasmid of ∼50 bp. The number of days that the patient received mechanical ventilation, the use of parenteral nutrition, previous treatment with linezolid, and treatment with extended-spectrum cephalosporins for more than 7 days were detected to be independent risk factors for CNSKP acquisition. The VIM-1-producing K. pneumoniae ST15 clone has a high capacity to spread among intensive care unit patients with severe underlying conditions. A high rate of associated mortality and great difficulty in controlling the spread of this clone, without permanent behavioral changes in the personnel, were observed. PMID:22005997

  9. Draft Genome Sequence of a Pseudomonas sp. Strain Carrying blaIMP-25 and blaVIM-2 Carbapenemase Genes from Hospital Sewage

    PubMed Central

    Hu, Yiyi; Wu, Wenjing; Feng, Yu; Zhang, Xiaoxia

    2016-01-01

    Pseudomonas strain WCHP16 recovered from hospital sewage in West China Hospital, Chengdu, China was found to carry two carbapenemase genes blaIMP-25 and blaVIM-2. Here, we report its 5.7-Mb draft genome sequence, comprising 141 contigs and an average 59.53% G+C content. The genome contained 5,504 coding sequences and 67 tRNA genes. PMID:27795238

  10. Similar Frequencies of Pseudomonas aeruginosa Isolates Producing KPC and VIM Carbapenemases in Diverse Genetic Clones at Tertiary-Care Hospitals in Medellín, Colombia

    PubMed Central

    Vanegas, Johanna M.; Cienfuegos, Astrid V.; Ocampo, Ana M.; López, Lucelly; del Corral, Helena; Roncancio, Gustavo; Sierra, Patricia; Echeverri-Toro, Lina; Ospina, Sigifredo; Maldonado, Natalia; Robledo, Carlos; Restrepo, Andrea

    2014-01-01

    Carbapenem-resistant Pseudomonas aeruginosa has become a serious health threat worldwide due to the limited options available for its treatment. Understanding its epidemiology contributes to the control of antibiotic resistance. The aim of this study was to describe the clinical and molecular characteristics of infections caused by carbapenem-resistant P. aeruginosa isolates in five tertiary-care hospitals in Medellín, Colombia. A cross-sectional study was conducted in five tertiary-care hospitals from June 2012 to March 2014. All hospitalized patients infected by carbapenem-resistant P. aeruginosa were included. Clinical information was obtained from medical records. Molecular analyses included PCR for detection of blaVIM, blaIMP, blaNDM, blaOXA-48, and blaKPC genes plus pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) for molecular typing. A total of 235 patients were enrolled: 91.1% of them were adults (n = 214), 88.1% (n = 207) had prior antibiotic use, and 14.9% (n = 35) had urinary tract infections. The blaVIM-2 and blaKPC-2 genes were detected in 13.6% (n = 32) and 11.5% (n = 27), respectively, of all isolates. Two isolates harbored both genes simultaneously. For KPC-producing isolates, PFGE revealed closely related strains within each hospital, and sequence types (STs) ST362 and ST235 and two new STs were found by MLST. With PFGE, VIM-producing isolates appeared highly diverse, and MLST revealed ST111 in four hospitals and five new STs. These results show that KPC-producing P. aeruginosa is currently disseminating rapidly and occurring at a frequency similar to that of VIM-producing P. aeruginosa isolates (approximately 1:1 ratio) in Medellín, Colombia. Diverse genetic backgrounds among resistant strains suggest an excessive antibiotic pressure resulting in the selection of resistant strains. PMID:25210071

  11. Photometric properties of Titan's surface from Cassini VIMS: Relevance to titan's hemispherical albedo dichotomy and surface stability

    USGS Publications Warehouse

    Nelson, R.M.; Brown, R.H.; Hapke, B.W.; Smythe, W.D.; Kamp, L.; Boryta, M.D.; Leader, F.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Buratti, B.J.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Combes, M.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Formisano, V.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.; Sotin, C.

    2006-01-01

    The Visual and Infrared Mapping Spectrometer (VIMS) instrument on the Cassini Saturn Orbiter returned spectral imaging data as the spacecraft undertook six close encounters with Titan beginning 7 July, 2004. Three of these flybys each produced overlapping coverage of two distinct regions of Titan's surface. Twenty-four points were selected on approximately opposite hemispheres to serve as photometric controls. Six points were selected in each of four reflectance classes. On one hemisphere each control point was observed at three distinct phase angles. From the derived phase coefficients, preliminary normal reflectances were derived for each reflectance class. The normal reflectance of Titan's surface units at 2.0178 ??m ranged from 0.079 to 0.185 for the most absorbing to the most reflective units assuming no contribution from absorbing haze. When a modest haze contribution of ??=0.1 is considered these numbers increase to 0.089-0.215. We find that the lowest three reflectance classes have comparable normal reflectance on either hemisphere. However, for the highest brightness class the normal reflectance is higher on the hemisphere encompassing longitude 14-65?? compared to the same high brightness class for the hemisphere encompassing 122-156?? longitude. We conclude that an albedo dichotomy observed in continental sized units on Titan is due not only to one unit having more areal coverage of reflective material than the other but the material on the brighter unit is intrinsically more reflective than the most reflective material on the other unit. This suggests that surface renewal processes are more widespread on Titan's more reflective units than on its less reflective units. We note that one of our photometric control points has increased in reflectance by 12% relative to the surrounding terrain from July of 2004 to April and May of 2005. Possible causes of this effect include atmospheric processes such as ground fog or orographic clouds; the suggestion of

  12. Rapid detection of blaNDM, blaKPC, blaIMP, and blaVIM carbapenemase genes in bacteria by loop-mediated isothermal amplification.

    PubMed

    Cheng, Cancan; Zheng, Fen; Rui, Yongyu

    2014-12-01

    A loop-mediated isothermal amplification (LAMP) assay was developed and evaluated for rapid detection of blaKPC, blaNDM, blaIMP, and blaVIM carbapenemase genes. Six oligonucleotides, including outer, inner, and loop primers, were designed for eight distinct regions in each target gene. Two qualitative criteria were used to evaluate LAMP reactions: visual inspection of color change and real-time detection of fluorescence change. The lower detection limit was 10 colony forming units (CFU) per reaction for real-time detection and 100 CFU per reaction for visual inspection for each gene. Two hundred twenty-two carbapenem-resistant clinical isolates (including 100 Pseudomonas aeruginosa, 100 Acinetobacter sp., and 22 Enterobacteriaceae) were tested by LAMP assay. At the same time, these isolates were confirmed by conventional polymerase chain reaction (PCR) and sequencing analysis. In these clinical isolates, the results of 11 strains with blaNDM, 11 strains with blaKPC, 11 strains with blaVIM, and 2 strains with blaIMP obtained using LAMP assays were concordant with conventional PCR. The LAMP method reported here may be a useful and powerful tool for rapid detection of blaNDM, blaKPC, blaIMP, and blaVIM carbapenemase genes in bacteria. PMID:25000338

  13. [blaVIM-2 gene detection in metallo-beta-lactamase-producing Pseudomonas aeruginosa strains isolated in an intensive care unit in Ciudad Bolívar, Venezuela].

    PubMed

    Guevara, Armando; de Waard, Jacobus; Araque, María

    2009-08-01

    Ten Pseudomonas aeruginosa strains with resistance to broad-spectrum cephalosporin and carbapenems were studied to determine the presence of genes that mediate the production of metallo-beta-lactamases. These strains were isolated from patients with nosocomial infection at the Intensive Care Unit of the Complejo Hospitalario "Ruiz y Paéz" of Ciudad Bolívar, Bolívar State, Venezuela, from 2003 to 2006. In all isolates a metallo-enzyme activity was detected by using the double disk synergism test. PCR amplification of genes encoding the families IMP, VIM and SPM metallo-beta-lactamases showed the presence of a blaVIM gene in all strains studied. DNA sequencing revealed that all isolates showed the presence of blaVIM-2. These results suggest that it is necessary to keep these strains under epidemiologic surveillance, establish laboratory strategies for opportune detection and the implementation of new policies to ensure the appropriate use of antibiotics in this institution.

  14. Rapid detection of blaNDM, blaKPC, blaIMP, and blaVIM carbapenemase genes in bacteria by loop-mediated isothermal amplification.

    PubMed

    Cheng, Cancan; Zheng, Fen; Rui, Yongyu

    2014-12-01

    A loop-mediated isothermal amplification (LAMP) assay was developed and evaluated for rapid detection of blaKPC, blaNDM, blaIMP, and blaVIM carbapenemase genes. Six oligonucleotides, including outer, inner, and loop primers, were designed for eight distinct regions in each target gene. Two qualitative criteria were used to evaluate LAMP reactions: visual inspection of color change and real-time detection of fluorescence change. The lower detection limit was 10 colony forming units (CFU) per reaction for real-time detection and 100 CFU per reaction for visual inspection for each gene. Two hundred twenty-two carbapenem-resistant clinical isolates (including 100 Pseudomonas aeruginosa, 100 Acinetobacter sp., and 22 Enterobacteriaceae) were tested by LAMP assay. At the same time, these isolates were confirmed by conventional polymerase chain reaction (PCR) and sequencing analysis. In these clinical isolates, the results of 11 strains with blaNDM, 11 strains with blaKPC, 11 strains with blaVIM, and 2 strains with blaIMP obtained using LAMP assays were concordant with conventional PCR. The LAMP method reported here may be a useful and powerful tool for rapid detection of blaNDM, blaKPC, blaIMP, and blaVIM carbapenemase genes in bacteria.

  15. A newly discovered impact crater in Titan's Senkyo: Cassini VIMS observations and comparison with other impact features

    USGS Publications Warehouse

    Buratti, B.J.; Sotin, C.; Lawrence, K.; Brown, R.H.; Le, Mouelic S.; Soderblom, J.M.; Barnes, J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.

    2012-01-01

    Senkyo is an equatorial plain on Titan filled with dunes and surrounded by hummocky plateaus. During the Titan targeted flyby T61 on August 25, 2009, the Cassini Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft observed a circular feature, centered at 5.4?? N and 341??W, that superimposes the dune fields and a bright plateau. This circular feature, which has been named Paxsi by the International Astronomical Union, is 120??10 km in diameter (measured from the outer edge of the crater rim) and exhibits a central bright area that can be interpreted as the central peak or pit of an impact crater. Although there are only a handful of certain impact craters on Titan, there are two other craters that are of similar size to this newly discovered feature and that have been studied by VIMS: Sinlap (Le Mou??lic et al, 2008) and Selk (Soderblom et al, 2010). Sinlap is associated with a large downwind, fan-like feature that may have been formed from an impact plume that rapidly expanded and deposited icy particles onto the surface. Although much of the surrounding region is covered with dunes, the plume region is devoid of dunes. The formation process of Selk also appears to have removed (or covered up) dunes from parts of the adjacent dune-filled terrain. The circular feature on Senkyo is quite different: there is no evidence of an ejecta blanket and the crater itself appears to be infilled with dune material. The rim of the crater appears to be eroded by fluvial processes; at one point the rim is breached. The rim is unusually narrow, which may be due to mass wasting on its inside and subsequent infill by dunes. Based on these observations, we interpret this newly discovered feature to be a more eroded crater than both Sinlap and Selk. Paxsi may have formed during a period when Titan was warmer and more ductile than it is currently. ?? 2011 Elsevier Ltd. All rights reserved.

  16. Compositional mapping of Saturn's satellite Dione with Cassini VIMS and implications of dark material in the Saturn system

    USGS Publications Warehouse

    Clark, R.N.; Curchin, J.M.; Jaumann, R.; Cruikshank, D.P.; Brown, R.H.; Hoefen, T.M.; Stephan, K.; Moore, Johnnie N.; Buratti, B.J.; Baines, K.H.; Nicholson, P.D.; Nelson, R.M.

    2008-01-01

    Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Dione provided key information for solving the riddle of the origin of the dark material in the Saturn system. The Dione VIMS data show a pattern of bombardment of fine, sub-0.5-??m diameter particles impacting the satellite from the trailing side direction. Multiple lines of evidence point to an external origin for the dark material on Dione, including the global spatial pattern of dark material, local patterns including crater and cliff walls shielding implantation on slopes facing away from the trailing side, exposing clean ice, and slopes facing the trailing direction which show higher abundances of dark material. Multiple spectral features of the dark material match those seen on Phoebe, Iapetus, Hyperion, Epimetheus and the F-ring, implying the material has a common composition throughout the Saturn system. However, the exact composition of the dark material remains a mystery, except that bound water and, tentatively, ammonia are detected, and there is evidence both for and against cyanide compounds. Exact identification of composition requires additional laboratory work. A blue scattering peak with a strong UV-visible absorption is observed in spectra of all satellites which contain dark material, and the cause is Rayleigh scattering, again pointing to a common origin. The Rayleigh scattering effect is confirmed with laboratory experiments using ice and 0.2-??m diameter carbon grains when the carbon abundance is less than about 2% by weight. Rayleigh scattering in solids is also confirmed in naturally occurring terrestrial rocks, and in previously published reflectance studies. The spatial pattern, Rayleigh scattering effect, and spectral properties argue that the dark material is only a thin coating on Dione's surface, and by extension is only a thin coating on Phoebe, Hyperion, and Iapetus, although the dark material abundance

  17. Storm clouds on Saturn: Lightning-induced chemistry and associated materials consistent with Cassini/VIMS spectra

    USGS Publications Warehouse

    Baines, K.H.; Delitsky, M.L.; Momary, T.W.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    Thunderstorm activity on Saturn is associated with optically detectable clouds that are atypically dark throughout the near-infrared. As observed by Cassini/VIMS, these clouds are ~20% less reflective than typical neighboring clouds throughout the spectral range from 0.8 ??m to at least 4.1 ??m. We propose that active thunderstorms originating in the 10-20 bar water-condensation region vertically transport dark materials at depth to the ~1 bar level where they can be observed. These materials in part may be produced by chemical processes associated with lightning, likely within the water clouds near the ~10 bar freezing level of water, as detected by the electrostatic discharge of lightning flashes observed by Cassini/RPWS (e.g., Fischer et al. 2008, Space Sci. Rev., 137, 271-285). We review lightning-induced pyrolytic chemistry involving a variety of Saturnian constituents, including hydrogen, methane, ammonia, hydrogen sulfide, phosphine, and water. We find that the lack of absorption in the 1-2 ??m spectral region by lightning-generated sulfuric and phosphorous condensates renders these constituents as minor players in determining the color of the dark storm clouds. Relatively small particulates of elemental carbon, formed by lightning-induced dissociation of methane and subsequently upwelled from depth - perhaps embedded within and on the surface of spectrally bright condensates such as ammonium hydrosulfide or ammonia - may be a dominant optical material within the dark thunderstorm-related clouds of Saturn. ?? 2009 Elsevier Ltd. All rights reserved.

  18. The structural and functional basis of the p97/valosin-containing protein (VCP)-interacting motif (VIM): mutually exclusive binding of cofactors to the N-terminal domain of p97.

    PubMed

    Hänzelmann, Petra; Schindelin, Hermann

    2011-11-01

    The AAA (ATPase associated with various cellular activities) ATPase p97, also referred to as valosin-containing protein (VCP), mediates essential cellular processes, including ubiquitin-dependent protein degradation, and has been linked to several human proteinopathies. p97 interacts with multiple cofactors via its N-terminal (p97N) domain, a subset of which contain the VCP-interacting motif (VIM). We have determined the crystal structure of the p97N domain in complex with the VIM of the ubiquitin E3 ligase gp78 at 1.8 Å resolution. The α-helical VIM peptide binds into a groove located in between the two subdomains of the p97N domain. Interaction studies of several VIM proteins reveal that these cofactors display dramatically different affinities, ranging from high affinity interactions characterized by dissociation constants of ∼20 nm for gp78 and ANKZF1 to only weak binding in our assays. The contribution of individual p97 residues to VIM binding was analyzed, revealing that identical substitutions do not affect all cofactors in the same way. Taken together, the biochemical and structural studies define the framework for recognition of VIM-containing cofactors by p97. Of particular interest to the regulation of p97 by its cofactors, our structure reveals that the bound α-helical peptides of VIM-containing cofactors overlap with the binding site for cofactors containing the ubiquitin regulatory X (UBX) domain present in the UBX protein family or the ubiquitin-like domain of NPL4 as further corroborated by biochemical data. These results extend the concept that competitive binding is a crucial determinant in p97-cofactor interactions.

  19. Self-gravity wake structures in Saturn's a ring revealed by Cassini vims

    USGS Publications Warehouse

    Hedman, M.M.; Nicholson, P.D.; Salo, H.; Wallis, B.D.; Buratti, B.J.; Baines, K.H.; Brown, R.H.; Clark, R.N.

    2007-01-01

    During the summer of 2005, the Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft observed a series of occultations of the star o Ceti (Mira) by Saturn's rings. These observations revealed pronounced variations in the optical depth of the A ring with longitude, which can be attributed to oriented structures in the rings known as self-gravity wakes. While the wakes themselves are only tens of meters across and below the resolution of the measurements, we are able to obtain information about the orientation and shapes of these structures by comparing the observed transmission at different longitudes with predictions from a simple model. Our findings include the following: (1) The orientation of the wakes varies systematically with radius, trailing by between 64?? and 72?? relative to the local radial direction. (2) The maximum transmission peaks at roughly 8% for B = 3.45?? in the middle A ring (???129,000 km). (3) Both the wake orientation and maximum transmission vary anomalously in the vicinity of two strong density waves (Janus 5:4 and Mimas 5:3). (4) The ratio of the wake vertical thickness H to the wake pattern wavelength ?? (assuming infinite, straight, regularly-spaced wake structures) varies from 0.12 to 0.09 across the A ring. Gravitational instability theory predicts ?? ??? 60 m, which suggests that the wake structures in the A ring are only ???6 m thick. ?? 2007. The American Astronomical Society. All rights reserved.

  20. Sub-wavelength plasmon laser

    DOEpatents

    Bora, Mihail; Bond, Tiziana C.

    2016-04-19

    A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

  1. Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers

    PubMed Central

    Jirauschek, Christian; Huber, Robert

    2015-01-01

    We analyze the physics behind the newest generation of rapidly wavelength tunable sources for optical coherence tomography (OCT), retaining a single longitudinal cavity mode during operation without repeated build up of lasing. In this context, we theoretically investigate the currently existing concepts of rapidly wavelength-swept lasers based on tuning of the cavity length or refractive index, leading to an altered optical path length inside the resonator. Specifically, we consider vertical-cavity surface-emitting lasers (VCSELs) with microelectromechanical system (MEMS) mirrors as well as Fourier domain mode-locked (FDML) and Vernier-tuned distributed Bragg reflector (VT-DBR) lasers. Based on heuristic arguments and exact analytical solutions of Maxwell’s equations for a fundamental laser resonator model, we show that adiabatic wavelength tuning is achieved, i.e., hopping between cavity modes associated with a repeated build up of lasing is avoided, and the photon number is conserved. As a consequence, no fundamental limit exists for the wavelength tuning speed, in principle enabling wide-range wavelength sweeps at arbitrary tuning speeds with narrow instantaneous linewidth. PMID:26203373

  2. SIX YEARS OF FERMI-LAT AND MULTI-WAVELENGTH MONITORING OF THE BROAD-LINE RADIO GALAXY 3C 120: JET DISSIPATION AT SUB-PARSEC SCALES FROM THE CENTRAL ENGINE

    SciTech Connect

    Tanaka, Y. T.; Doi, A.; Inoue, Y.; Stawarz, L.; Cheung, C. C.; Fukazawa, Y.; Itoh, R.; Gurwell, M. A.; Tahara, M.; Kataoka, J.

    2015-01-30

    We present multi-wavelength monitoring results for the broad-line radio galaxy 3C 120 in the MeV/GeV, sub-millimeter, and 43 GHz bands over 6 yr. Over the past 2 yr, the Fermi-Large Area Telescope sporadically detected 3C 120 with high significance and the 230 GHz data also suggest an enhanced activity of the source. After the MeV/GeV detection from 3C 120 in MJD 56240–56300, 43 GHz Very Long Baseline Array (VLBA) monitoring revealed a brightening of the radio core, followed by the ejection of a superluminal knot. Since we observed the γ-ray and VLBA phenomena in temporal proximity to each other, it is naturally assumed that they are physically connected. This assumption was further supported by the subsequent observation that the 43 GHz core brightened again after a γ-ray flare occurred around MJD 56560. We can then infer that the MeV/GeV emission took place inside an unresolved 43 GHz core of 3C 120 and that the jet dissipation occurred at sub-parsec distances from the central black hole (BH), if we take the distance of the 43 GHz core from the central BH as ∼0.5 pc, as previously estimated from the time lag between X-ray dips and knot ejections. Based on our constraints on the relative locations of the emission regions and energetic arguments, we conclude that the γ rays are more favorably produced via the synchrotron self-Compton process, rather than inverse Compton scattering of external photons coming from the broad line region or hot dusty torus. We also derived the electron distribution and magnetic field by modeling the simultaneous broadband spectrum.

  3. Titan: Preliminary results on surface properties and photometry from VIMS observations of the early flybys

    USGS Publications Warehouse

    Buratti, B.J.; Sotin, C.; Brown, R.H.; Hicks, M.D.; Clark, R.N.; Mosher, J.A.; McCord, T.B.; Jaumann, R.; Baines, K.H.; Nicholson, P.D.; Momary, T.; Simonelli, D.P.; Sicardy, B.

    2006-01-01

    Cassini observations of the surface of Titan offer unprecedented views of its surface through atmospheric windows in the 1-5 ??m region. Images obtained in windows for which the haze opacity is low can be used to derive quantitative photometric parameters such as albedo and albedo distribution, and physical properties such as roughness and particle characteristics. Images from the early Titan flybys, particularly T0, Ta, and T5 have been analyzed to create albedo maps in the 2.01 and 2.73 ??m windows. We find the average normal reflectance at these two wavelengths to be 0.15??0.02 and 0.035??0.003, respectively. Titan's surface is bifurcated into two albedo regimes, particularly at 2.01 ??m. Analysis of these two regimes to understand the physical character of the surface was accomplished with a macroscopic roughness model. We find that the two types of surface have substantially different roughness, with the low-albedo surface exhibiting mean slope angles of ???18??, and the high-albedo terrain having a much more substantial roughness with a mean slope angle of ???34??. A single-scattering phase function approximated by a one-term Henyey-Greenstein equation was also fit to each unit. Titan's surface is back-scattering (g???0.3-0.4), and does not exhibit substantially different backscattering behavior between the two terrains. Our results suggest that two distinct geophysical domains exist on Titan: a bright region cut by deep drainage channels and a relatively smooth surface. The two terrains are covered by a film or a coating of particles perhaps precipitated from the satellite's haze layer and transported by eolian processes. Our results are preliminary: more accurate values for the surface albedo and physical parameters will be derived as more data is gathered by the Cassini spacecraft and as a more complete radiative transfer model is developed from both Cassini orbiter and Huygens Lander measurements. ?? 2006 Elsevier Ltd. All rights reserved.

  4. Wavelength-modulated photocapacitance spectroscopy

    NASA Technical Reports Server (NTRS)

    Kamieniecki, E.; Lagowski, J.; Gatos, H. C.

    1980-01-01

    Derivative deep-level spectroscopy was achieved with wavelength-modulated photocapacitance employing MOS structures and Schottky barriers. The energy position and photoionization characteristics of deep levels of melt-grown GaAs and the Cr level in high-resistivity GaAs were determined. The advantages of this method over existing methods for deep-level spectroscopy are discussed.

  5. Solid colloidal optical wavelength filter

    DOEpatents

    Alvarez, Joseph L.

    1992-01-01

    A solid colloidal optical wavelength filter includes a suspension of spheal particles dispersed in a coagulable medium such as a setting plastic. The filter is formed by suspending spherical particles in a coagulable medium; agitating the particles and coagulable medium to produce an emulsion of particles suspended in the coagulable medium; and allowing the coagulable medium and suspended emulsion of particles to cool.

  6. Wavelength-shifted Cherenkov radiators

    NASA Technical Reports Server (NTRS)

    Krider, E. P.; Jacobson, V. L.; Pifer, A. E.; Polakos, P. A.; Kurz, R. J.

    1976-01-01

    The scintillation and Cherenkov responses of plastic Cherenkov radiators containing different wavelength-shifting fluors in varying concentrations have been studied in beams of low energy protons and pions. For cosmic ray applications, where large Cherenkov to scintillation ratios are desired, the optimum fluor concentrations are 0.000025 by weight or less.

  7. Long wavelength vertical-cavity light-emitting devices

    NASA Astrophysics Data System (ADS)

    Christenson, Gina Lee

    Long wavelength tunable transmitters are essential in the field of optical communications. Wavelength control and cost reduction are very important issues, especially in applications such as wavelength division multiplexing (WDM) networks, where several closely spaced wavelengths are transmitted and processed simultaneously. This thesis introduces a transmitter design that can alleviate these problems. This work involves the development, fabrication, and characterization of a narrowband tunable resonant cavity light-emitting diode (LED). The emission is centered at 1.51 mum, an important wavelength for optical communications. The linewidth is only 4 nm and the tuning range covers 75 nm. Wafer bonding and surface micromachining techniques have been integrated in the design to produce a structure that combines the assets of each technology. Wafer bonding is used to build the base for a vertical cavity surface emitting laser (VCSEL) structure, which is composed of an InP-based active layer on a GaAs-based mirror. Surface micromachining is then used to fabricate the suspended top mirror of the VCSEL, in place of the traditional top mirror that is grown directly on the VCSEL structure. The suspended mirror moves towards the substrate with the application of a voltage, thus changing the Fabry-Perot cavity length and providing the wavelength tunability of the device. This transmitter design relaxes the need for preset wavelengths in VCSEL processing by allowing the user to adjust the central wavelength after processing. Arrays of transmitters with identical wavelengths for high power applications or with gradually decreasing emission wavelengths across a wafer can also be achieved. The tunability of the devices allows for real time wavelength monitoring and tracking to ensure stability of the wavelengths with temperature or environmental changes, as well as compensating for shifts in wavelength due to degradation of the devices over time. Due to the monolithic, vertical

  8. On the discovery of CO nighttime emissions on Titan by Cassini/VIMS: Derived stratospheric abundances and geological implications

    USGS Publications Warehouse

    Baines, K.H.; Drossart, P.; Lopez-Valverde, M. A.; Atreya, S.K.; Sotin, C.; Momary, T.W.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2006-01-01

    We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147]. in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 ??m. For CH3D, the prominent Q branch of the ??2 fundamental band of CH3D near 4.55 ??m is apparent. CO2 emissions from the strong v3 vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32??15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is ???2.9??1.5??1014 kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (???0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6??3??105 kg yr-1. Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8??0.9??10-4, based on an average methane surface emission rate over the past 0.5 Gyr of 1.3??10-13 gm cm-2 s-1 as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere. J. Geophys. Res. 109, E06002 Doi:10.1029/2003JE002181]. This

  9. On the Discovery of CO Nighttime Emissions on Titan by Cassini/VIMS: Derived Stratospheric Abundances and Geological Implications

    NASA Technical Reports Server (NTRS)

    Bainesa, Kevin H.; Drossart, Pierre; Lopez-Valverde, Miguel A.; Atreya, Sushil K.; Sotin, Christophe; Momary, Thomas W.; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.

    2006-01-01

    We present a quantitative analysis of CO thermal emissions discovered on the nightside of Titan by Baines et al. [2005. The atmospheres of Saturn and Titan in the near-infrared: First results of Cassini/VIMS. Earth, Moon, and Planets, 96, 119-147] in Cassini/VIMS spectral imagery. We identify these emission features as the P and R branches of the 1-0 vibrational band of carbon monoxide (CO) near 4.65 microns. For CH3D, the prominent Q branch of the nu(2) fundamental band of CH3D near 4.55 microns is apparent. CO2 emissions from the strong nu(3) vibrational band are virtually absent, indicating a CO2 abundance several orders of magnitude less than CO, in agreement with previous investigations. Analysis of CO emission spectra obtained over a variety of altitudes on Titan's nightside limb indicates that the stratospheric abundance of CO is 32 +/- 15 ppm, and together with other recent determinations, suggests a vertical distribution of CO nearly constant at this value from the surface throughout the troposphere to at least the stratopause near 300 km altitude. The corresponding total atmospheric content of CO in Titan is similar to 2.9 +/- 1.5 x 10(exp 14) kg. Given the long lifetime of CO in the oxygen-poor Titan atmosphere (similar to 0.5-1.0 Gyr), we find a mean CO atmospheric production rate of 6 +/- 3 x 10(exp 5) kg yr(exp -1). Given the lack of primordial heavy noble gases observed by Huygens [Niemann et al., 2005. The abundances of constituents of Titan's atmosphere from the GCMS on the Huygens probe. Nature, 438, 779-784], the primary source of atmospheric CO is likely surface emissions. The implied CO/CH4 mixing ratio of near-surface material is 1.8 +/- 0.9 x 10(exp -4), based on an average methane surface emission rate over the past 0.5 Gyr of 1.3 x 10(exp -13) gm cm(exp -2) s(exp -1) as required to balance hydrocarbon haze production via methane photolysis [Wilson and Atreya, 2004. Current state of modeling the photochemistry of Titan's mutually dependent

  10. Review of short wavelength lasers

    SciTech Connect

    Hagelstein, P.L.

    1985-03-18

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

  11. Spread of TEM, VIM, SHV, and CTX-M β-Lactamases in Imipenem-Resistant Gram-Negative Bacilli Isolated from Egyptian Hospitals.

    PubMed

    Hamdy Mohammed, El Sayed; Elsadek Fakhr, Ahmed; Mohammed El Sayed, Hanan; Al Johery, Said Abd Elmohsen; Abdel Ghani Hassanein, Wesam

    2016-01-01

    Carbapenem-resistant Gram-negative bacilli resulting from β-lactamases have been reported to be an important cause of nosocomial infections and are a critical therapeutic problem worldwide. This study aimed to describe the prevalence of imipenem-resistant Gram-negative bacilli isolates and detection of bla VIM, bla TEM, bla SHV, bla CTX-M-1, and bla CTX-M-9 genes in these clinical isolates in Egyptian hospitals. The isolates were collected from various clinical samples, identified by conventional methods and confirmed by API 20E. Antibiotic susceptibility testing was determined by Kirby-Bauer technique and interpreted according to CLSI. Production of bla VIM, bla TEM, bla SHV, and bla CTX-M genes was done by polymerase chain reaction (PCR). Direct sequencing from PCR products was subsequently carried out to identify and confirm these β-lactamases genes. Out of 65 isolates, (46.1%) Escherichia coli, (26.2%) Klebsiella pneumoniae, and (10.7%) Pseudomonas aeruginosa were identified as the commonest Gram-negative bacilli. 33(50.8%) were imipenem-resistant isolates. 22 isolates (66.7%) carried bla VIM, 24(72.7%) had bla TEM, and 5(15%) showed bla SHV, while 12(36%), 6(18.2%), and 0(0.00%) harbored bla CTX-M-1, bla CTX-M-9, and bla CTX-M-8/25, respectively. There is a high occurrence of β-lactamase genes in clinical isolates and sequence analysis of amplified genes showed differences between multiple SNPs (single nucleotide polymorphism) sites in the same gene among local isolates in relation to published sequences. PMID:27123005

  12. Spread of TEM, VIM, SHV, and CTX-M β-Lactamases in Imipenem-Resistant Gram-Negative Bacilli Isolated from Egyptian Hospitals

    PubMed Central

    Hamdy Mohammed, El sayed; Elsadek Fakhr, Ahmed; Mohammed El sayed, Hanan; Al Johery, Said abd Elmohsen; Abdel Ghani Hassanein, Wesam

    2016-01-01

    Carbapenem-resistant Gram-negative bacilli resulting from β-lactamases have been reported to be an important cause of nosocomial infections and are a critical therapeutic problem worldwide. This study aimed to describe the prevalence of imipenem-resistant Gram-negative bacilli isolates and detection of blaVIM, blaTEM, blaSHV, blaCTX-M-1, and blaCTX-M-9 genes in these clinical isolates in Egyptian hospitals. The isolates were collected from various clinical samples, identified by conventional methods and confirmed by API 20E. Antibiotic susceptibility testing was determined by Kirby-Bauer technique and interpreted according to CLSI. Production of blaVIM, blaTEM, blaSHV, and blaCTX-M genes was done by polymerase chain reaction (PCR). Direct sequencing from PCR products was subsequently carried out to identify and confirm these β-lactamases genes. Out of 65 isolates, (46.1%) Escherichia coli, (26.2%) Klebsiella pneumoniae, and (10.7%) Pseudomonas aeruginosa were identified as the commonest Gram-negative bacilli. 33(50.8%) were imipenem-resistant isolates. 22 isolates (66.7%) carried blaVIM, 24(72.7%) had blaTEM, and 5(15%) showed blaSHV, while 12(36%), 6(18.2%), and 0(0.00%) harbored blaCTX-M-1, blaCTX-M-9, and blaCTX-M-8/25, respectively. There is a high occurrence of β-lactamase genes in clinical isolates and sequence analysis of amplified genes showed differences between multiple SNPs (single nucleotide polymorphism) sites in the same gene among local isolates in relation to published sequences. PMID:27123005

  13. Evolution of a Dark Anti-Cyclone on Saturn Associated with the Great Lightning Storm of 2010/2011 Through the Eyes of Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Momary, Thomas W.; Baines, K. H.; Brown, R. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.; Sotin, C.

    2012-10-01

    A massive dark anti-cyclonic storm system on Saturn spanning some 7∘ of longitude and 2∘ of latitude was observed by Cassini/VIMS at a planetocentric latitude of 37∘ on 4 January 2012 and 26 January 2012. During this time, it drifted some 54∘ of longitude at a speed of 23.1 ± 0.2 m/s prograde, a drift speed which correlates well with the canonical Voyager (and VIMS) wind profiles for Saturn at this latitude. The spot also drifted northward during this time by 1∘ and became noticeably "squished" in morphology. Using this drift rate and extrapolating backward, we find that the position corresponds to the large (> 5,000 km) anti-cyclone observed by VIMS on 11 May 2011 at 35.4∘ latitude (pc) and 49.4∘ W. longitude. This would represent 8 months of observation of this titanic feature, which was associated with the major lightning storm of 2010-2011, following the spot as it changed in size and morphology and drifted northward. The spot underwent a dramatic shift in shape in the 3 weeks of January, changing from roughly oval to a highly elongated pancake shape as it apparently bumped up against the dark band at 40∘ latitude and experienced a powerful shear. The evolution suggests that we are watching the death throes of this feature in our most recent observations. Finally, the dark spot was darker than surrounding regions in May 2011 and maintained its dark color across all pseudo-continua from 1.0 to 4.0 μm between May 2011 and early January 2012.

  14. Laser wavelengths and oral implantology.

    PubMed

    Romanos, George E; Gutknecht, Norbert; Dieter, Sandra; Schwarz, Frank; Crespi, Roberto; Sculean, Anton

    2009-11-01

    In modern implant dentistry there are several clinical indications for laser surgery. Different laser systems have a considerable spectrum of application in soft and hard peri-implant tissues. The literature was searched for clinical application of different laser wavelengths in peri-implant tissues: second-stage surgery of submerged implants, treatment of infrabony defects, removal of peri-implant hyperplastic overgrowths, and, possibly, the preparation of bone cavities for implant placement. This report describes the state-of-the-art application of different laser systems in modern implant dentistry for the treatment of peri-implant lesions and decontamination of implant surfaces. Our study evaluated in vitro examinations, clinical experience and long-term clinical studies. The exact selection of the appropriate laser system and wavelength was dependent on the scientific evaluation of recent literature and the level of changes in implant and tissue temperatures during laser application. The significant reduction in bacteria on the implant surface and the peri-implant tissues during irradiation and the cutting effects associated with the coagulation properties of the lasers are the main reasons for laser application in the treatment of peri-implant lesions and the successful long-term prognosis of failing oral implants. The various applications of lasers in implant dentistry are dependent on the wavelength and laser-tissue interactions.

  15. Far-field measurements of short-wavelength surface plasmons

    SciTech Connect

    Blau, Yochai; Gjonaj, Bergin; David, Asaf; Dolev, Shimon; Shterman, Doron; Bartal, Guy

    2015-03-23

    We present direct far-field measurements of short-wavelength surface plasmon polaritons (SPP) by conventional optics means. Plasmonic wavelength as short as 231 nm was observed for 532 nm illumination on a Ag−Si{sub 3}N{sub 4} platform, demonstrating the capability to characterize SPPs well below the optical diffraction limit. This is done by scaling a sub-wavelength interferometric pattern to a far-field resolvable periodicity. These subwavelength patterns are obtained by coupling light into counter-propagating SPP waves to create a standing-wave pattern of half the SPP wavelength periodicity. Such patterns are mapped by a scattering slit, tilted at an angle so as to increase the periodicity of the intensity pattern along it to more than the free-space wavelength, making it resolvable by diffraction limited optics. The simplicity of the method as well as its large dynamic range of measurable wavelengths make it an optimal technique to characterize the properties of plasmonic devices and high-index dielectric waveguides, to improve their design accuracy and enhance their functionality.

  16. Multi-wavelength modeling of protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Pinte, C.; Ménard, F.; Duchêne, G.; Augereau, J.-C.

    2006-06-01

    The on-going revolution of high angular resolution observations and increasing wavelength coverage promises to unlock tightly-kept secrets of circumstellar disks. Thanks to these advances, many issues have already been addressed : large scale geometry of disks, evidence of grain growth, of dust settling, ldots Most of these results are based on models that emphasize on fitting either SEDs or scattered light images or, more recently, interferometric visibilities. In this contribution, we present a global approach which aims at interpreting the increasing amount of observational data coherently, in the framework of a single model, in order to get a more global picture and to better characterize both the dust population and the disk properties. Results of such a modeling approach, applied to a few disks for which large observational data-sets are available, are presented.

  17. Wavelength stabilized multi-kW diode laser systems

    NASA Astrophysics Data System (ADS)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  18. Sequence of pNL194, a 79.3-kilobase IncN plasmid carrying the blaVIM-1 metallo-beta-lactamase gene in Klebsiella pneumoniae.

    PubMed

    Miriagou, V; Papagiannitsis, C C; Kotsakis, S D; Loli, A; Tzelepi, E; Legakis, N J; Tzouvelekis, L S

    2010-10-01

    The nucleotide sequence of pNL194, a VIM-1-encoding plasmid, is described in this study. pNL194 (79,307 bp) comprised an IncN-characteristic segment (38,940 bp) and a mosaic structure (40,367 bp) including bla(VIM-1), aacA7, aadA1, aadA2, dfrA1, dfrA12, aphA1, strA, strB, and sul1. Tn1000 or Tn5501 insertion within fipA probably facilitated recruitment of additional mobile elements carrying resistance genes. PMID:20660690

  19. Sequence of pNL194, a 79.3-Kilobase IncN Plasmid Carrying the blaVIM-1 Metallo-β-Lactamase Gene in Klebsiella pneumoniae▿

    PubMed Central

    Miriagou, V.; Papagiannitsis, C. C.; Kotsakis, S. D.; Loli, A.; Tzelepi, E.; Legakis, N. J.; Tzouvelekis, L. S.

    2010-01-01

    The nucleotide sequence of pNL194, a VIM-1-encoding plasmid, is described in this study. pNL194 (79,307 bp) comprised an IncN-characteristic segment (38,940 bp) and a mosaic structure (40,367 bp) including blaVIM-1, aacA7, aadA1, aadA2, dfrA1, dfrA12, aphA1, strA, strB, and sul1. Tn1000 or Tn5501 insertion within fipA probably facilitated recruitment of additional mobile elements carrying resistance genes. PMID:20660690

  20. Sequence of pNL194, a 79.3-kilobase IncN plasmid carrying the blaVIM-1 metallo-beta-lactamase gene in Klebsiella pneumoniae.

    PubMed

    Miriagou, V; Papagiannitsis, C C; Kotsakis, S D; Loli, A; Tzelepi, E; Legakis, N J; Tzouvelekis, L S

    2010-10-01

    The nucleotide sequence of pNL194, a VIM-1-encoding plasmid, is described in this study. pNL194 (79,307 bp) comprised an IncN-characteristic segment (38,940 bp) and a mosaic structure (40,367 bp) including bla(VIM-1), aacA7, aadA1, aadA2, dfrA1, dfrA12, aphA1, strA, strB, and sul1. Tn1000 or Tn5501 insertion within fipA probably facilitated recruitment of additional mobile elements carrying resistance genes.

  1. Note: Laser wavelength precision measurement based on a laser synthetic wavelength interferometer

    NASA Astrophysics Data System (ADS)

    Yan, Liping; Chen, Benyong; Zhang, Shihua; Liu, Pengpeng; Zhang, Enzheng

    2016-08-01

    A laser wavelength precision measurement method is presented based on the laser synthetic wavelength interferometer (LSWI). According to the linear relation between the displacements of measurement and reference arms in the interferometer, the synthetic wavelength produced by an unknown wavelength and a reference wavelength can be measured by detecting the phase coincidences of two interference signals. The advantage of the method is that a larger synthetic wavelength resulting from an unknown wavelength very close to the reference wavelength can be easily determined according to the linear relation in the interferometer. Then the unknown wavelength is derived according to the one-to-one corresponding relationship between single wavelength and synthetic wavelength. Wavelengths of an external cavity diode laser and two He-Ne lasers were determined experimentally. The experimental results show that the proposed method is able to realize a relative uncertainty on the order of 10-8.

  2. Note: Laser wavelength precision measurement based on a laser synthetic wavelength interferometer.

    PubMed

    Yan, Liping; Chen, Benyong; Zhang, Shihua; Liu, Pengpeng; Zhang, Enzheng

    2016-08-01

    A laser wavelength precision measurement method is presented based on the laser synthetic wavelength interferometer (LSWI). According to the linear relation between the displacements of measurement and reference arms in the interferometer, the synthetic wavelength produced by an unknown wavelength and a reference wavelength can be measured by detecting the phase coincidences of two interference signals. The advantage of the method is that a larger synthetic wavelength resulting from an unknown wavelength very close to the reference wavelength can be easily determined according to the linear relation in the interferometer. Then the unknown wavelength is derived according to the one-to-one corresponding relationship between single wavelength and synthetic wavelength. Wavelengths of an external cavity diode laser and two He-Ne lasers were determined experimentally. The experimental results show that the proposed method is able to realize a relative uncertainty on the order of 10(-8). PMID:27587172

  3. Optimal laser wavelength for photoacoustic imaging of breast microcalcifications

    NASA Astrophysics Data System (ADS)

    Kang, Jeeun; Kim, Eun-Kyung; Young Kwak, Jin; Yoo, Yangmo; Song, Tai-Kyong; Ho Chang, Jin

    2011-10-01

    This paper presents photoacoustic imaging (PAI) for real-time detection of micro-scale calcifications (e.g., <1 mm) in the breast, which are an indicator of the cancer occurrence. Optimal wavelength of incident laser for the microcalcification imaging was ascertained through ex vivo experiments with seven breast specimens of volunteers. In the ex vivo experiments, the maximum amplitude of photoacoustic signals from the microcalcifications occurred when the laser wavelength ranged from 690 to 700 nm. This result demonstrated that PAI can serve as a real-time imaging and guidance tool for diagnosis and biopsy of the breast microcalcifications.

  4. Wavelength tunable alexandrite regenerative amplifier

    SciTech Connect

    Harter, D.J.; Bado, P.

    1988-11-01

    We describe a wavelength tunable alexandrite regenerative amplifier which is used to amplify nanosecond slices from a single-frequency cw dye laser or 50-ps pulses emitted by a diode laser to energies in the 10-mJ range. The amplified 5-ns slices generated by the cw-pumped line narrowed dye laser are Fourier transform limited. The 50-ps pulses emitted by a gain-switched diode laser are amplified by more than 10 orders of magnitude in a single stage.

  5. Plasmonic lens for ultraviolet wavelength

    NASA Astrophysics Data System (ADS)

    Takeda, Minoru; Tanimoto, Takuya; Inoue, Tsutomu; Aizawa, Kento

    2016-09-01

    A plasmonic lens (PL) is one of the promising photonic devices utilizing the surface plasmon wave. In this study, we have newly developed a PL with a 3.5 µm diameter for a wavelength of 375 nm (ultraviolet region). It is composed of multiple circular slit apertures milled in aluminum (Al) thin film. We have simulated the electric field distribution of the PL, and confirmed that a tightly focused beam spot of subwavelength size in the far-field region was attained. We have also measured the focusing characteristics of the PL using a near-field scanning optical microscope (NSOM) and compared them with the calculated results.

  6. Quantum information processing with long-wavelength radiation

    NASA Astrophysics Data System (ADS)

    Murgia, David; Weidt, Sebastian; Randall, Joseph; Lekitsch, Bjoern; Webster, Simon; Navickas, Tomas; Grounds, Anton; Rodriguez, Andrea; Webb, Anna; Standing, Eamon; Pearce, Stuart; Sari, Ibrahim; Kiang, Kian; Rattanasonti, Hwanjit; Kraft, Michael; Hensinger, Winfried

    To this point, the entanglement of ions has predominantly been performed using lasers. Using long wavelength radiation with static magnetic field gradients provides an architecture to simplify construction of a large scale quantum computer. The use of microwave-dressed states protects against decoherence from fluctuating magnetic fields, with radio-frequency fields used for qubit manipulation. I will report the realisation of spin-motion entanglement using long-wavelength radiation, and a new method to efficiently prepare dressed-state qubits and qutrits, reducing experimental complexity of gate operations. I will also report demonstration of ground state cooling using long wavelength radiation, which may increase two-qubit entanglement fidelity. I will then report demonstration of a high-fidelity long-wavelength two-ion quantum gate using dressed states. Combining these results with microfabricated ion traps allows for scaling towards a large scale ion trap quantum computer, and provides a platform for quantum simulations of fundamental physics. I will report progress towards the operation of microchip ion traps with extremely high magnetic field gradients for multi-ion quantum gates.

  7. Modal interactions between a large-wavelength inclined interface and small-wavelength multimode perturbations in a Richtmyer-Meshkov instability

    NASA Astrophysics Data System (ADS)

    McFarland, Jacob A.; Reilly, David; Black, Wolfgang; Greenough, Jeffrey A.; Ranjan, Devesh

    2015-07-01

    The interaction of a small-wavelength multimodal perturbation with a large-wavelength inclined interface perturbation is investigated for the reshocked Richtmyer-Meshkov instability using three-dimensional simulations. The ares code, developed at Lawrence Livermore National Laboratory, was used for these simulations and a detailed comparison of simulation results and experiments performed at the Georgia Tech Shock Tube facility is presented first for code validation. Simulation results are presented for four cases that vary in large-wavelength perturbation amplitude and the presence of secondary small-wavelength multimode perturbations. Previously developed measures of mixing and turbulence quantities are presented that highlight the large variation in perturbation length scales created by the inclined interface and the multimode complex perturbation. Measures are developed for entrainment, and turbulence anisotropy that help to identify the effects of and competition between each perturbations type. It is shown through multiple measures that before reshock the flow processes a distinct memory of the initial conditions that is present in both large-scale-driven entrainment measures and small-scale-driven mixing measures. After reshock the flow develops to a turbulentlike state that retains a memory of high-amplitude but not low-amplitude large-wavelength perturbations. It is also shown that the high-amplitude large-wavelength perturbation is capable of producing small-scale mixing and turbulent features similar to the small-wavelength multimode perturbations.

  8. Compact silicon photonic wavelength-tunable laser diode with ultra-wide wavelength tuning range

    SciTech Connect

    Kita, Tomohiro Tang, Rui; Yamada, Hirohito

    2015-03-16

    We present a wavelength-tunable laser diode with a 99-nm-wide wavelength tuning range. It has a compact wavelength-tunable filter with high wavelength selectivity fabricated using silicon photonics technology. The silicon photonic wavelength-tunable filter with wide wavelength tuning range was realized using two ring resonators and an asymmetric Mach-Zehnder interferometer. The wavelength-tunable laser diode fabricated by butt-joining a silicon photonic filter and semiconductor optical amplifier shows stable single-mode operation over a wide wavelength range.

  9. Compact silicon photonic wavelength-tunable laser diode with ultra-wide wavelength tuning range

    NASA Astrophysics Data System (ADS)

    Kita, Tomohiro; Tang, Rui; Yamada, Hirohito

    2015-03-01

    We present a wavelength-tunable laser diode with a 99-nm-wide wavelength tuning range. It has a compact wavelength-tunable filter with high wavelength selectivity fabricated using silicon photonics technology. The silicon photonic wavelength-tunable filter with wide wavelength tuning range was realized using two ring resonators and an asymmetric Mach-Zehnder interferometer. The wavelength-tunable laser diode fabricated by butt-joining a silicon photonic filter and semiconductor optical amplifier shows stable single-mode operation over a wide wavelength range.

  10. Multi-wavelength fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Kwong, Tiffany C.; Lo, Pei-An; Cho, Jaedu; Nouizi, Farouk; Chiang, Huihua K.; Kim, Chang-Seok; Gulsen, Gultekin

    2016-03-01

    The strong scattering and absorption of light in biological tissue makes it challenging to model the propagation of light, especially in deep tissue. This is especially true in fluorescent tomography, which aims to recover the internal fluorescence source distribution from the measured light intensities on the surface of the tissue. The inherently ill-posed and underdetermined nature of the inverse problem along with strong tissue scattering makes Fluorescence Tomography (FT) extremely challenging. Previously, multispectral detection fluorescent tomography (FT) has been shown to improve the image quality of FT by incorporating the spectral filtering of biological tissue to provide depth information to overcome the inherent absorption and scattering limitations. We investigate whether multi-wavelength fluorescent tomography can be used to distinguish the signals from multiple fluorophores with overlapping fluorescence spectrums using a unique near-infrared (NIR) swept laser. In this work, a small feasibility study was performed to see whether multi-wavelength FT can be used to detect subtle shifts in the absorption spectrum due to differences in fluorophore microenvironment.

  11. Spectral and morphological properties of various geological types of Titan’s surface with Cassini VIMS and RADAR

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Lopes, Rosaly M.; Hirtzig, Mathieu; Rodriguez, Sebastien; Malaska, Michael; Drossart, Pierre; Sotin, Christophe; Bratsolis, Emmanuel; Matsoukas, Chris; Brown, Robert; Maltagliati, Luca

    2015-08-01

    Cassini’s VIMS and the RADAR have been investigating Titan’s surface since 2004. Both instruments unveiled the dynamic and complex surface expressions of this Saturnian moon, suggesting exogenic and endogenic processes [1;2;3]. In order to evaluate the atmospheric contribution and thereafter extract surface information, a Radiative transfer code is used to analyse different regions and to monitor their spectral behaviour over time [4;5;7]. We furthermore use RADAR despeckled SAR images to infer information on the morphology [6]. We find that temporal variations of surface albedo occur for some areas, but that their origin may differ from one region to the other. Tui Regio and Sotra Patera change with time becoming darker and brighter respectively in terms of surface albedo. In contrast, we find that the undifferentiated plains and the suggested evaporitic areas in the equatorial regions do not present any significant change [5]. This observation supports the hypothesis that Titan is surface brightening of Sotra supports a possible internal rather than an exogenic origin. This observation supports the hypothesis that Titan is a cryovolcanic world due to the presence of local complex volcanic-like geomorphology [1] and indications of surface albedo changes [4,5]. Potential sources of the energy for cryovolcanism include tidal heating, possible internal convection, and ice tectonics, is believed to be a pre-requisite of a habitable planetary body as it allows the recycling of minerals and potential nutrients and provides localized energy sources. A recent study has shown that tidal forces are a constant and significant source of internal deformation on Titan and the interior liquid water ocean can be relatively warm for reasonable amounts of ammonia concentrations [8].[1] Lopes, R.M.C., et al. JGR, 118, 2013 [2] Solomonidou, A., et al. PSS, 70, 2013 [3] Moore, J.M. GRL, 37, 2010 [4] Solomonidou, A., et al. JGR, 119, 2014 [5] Solomonidou, A., et al. submitted [6

  12. The Evolution of Saturn’s Storm-Perturbed Latitudinal Band Determined from Cassini/VIMS Daytime and Nighttime Spectra

    NASA Astrophysics Data System (ADS)

    Baines, K. H.; Sromovsky, Larry A.; Fry, Patrick M.; Moimary, Thomas W.; Badman, Sarah; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.; Sotin, Christophe

    2015-11-01

    Saturn’s Great Storm of 2010-2011 was one of the most powerful convective events ever witnessed, as indicated, for example, by its ability to deliver spectrally-identifiable water ice to the top of its convective tower ~200 km above the water vapor condensation level near 20 bar (Sromovsky, L. A., et al., Icarus 226, 402-418. 2013), and by its ability over ~ 6 months to encircle the planet with apparently anvil-like ammonia clouds sheared away from the top of its convective tower(s). Within a half-year after the storm subsided in mid-2011, these globe-encircling anvil-like clouds appeared to have largely disappeared, replaced by a 5-micron-bright band encircling the planet over nearly the same latitude region the storm generated clouds had been, indicating a dramatic decrease in the opacity of aerosols sensitive to 5-micron radiation (heat) emanating from the warm depths of the planet. Here we present quantitative results on the 5-year evolution of this storm-affected, 5-micron-bright region, from its initial appearance associated with a large anti-cyclone that formed in the Spring of 2011 through May 26-27, 2015, using both daytime and nighttime Cassini/VIMS spectral maps. Compared to the “normal”, unperturbed regional cloud structure upstream of the storm as observed on Feb 24, 2011, we find that the initial 5-micron-bright region on May 11, 2011 had lost ~60% of its upper-cloud (100-500 mbar) opacity (i. e., nominally, 2.7 opacity post-storm at 2-microns vs 7.1 pre-storm) and that the pressure of an opaque, putatively NH4SH, optically-thick “sheet” cloud dropped in altitude from a pre-storm level of 2.9 bar to the 3.2-bar level post-storm. Subsequently over the next 4 years, the upper-cloud region recovered half of its lost opacity, reaching ~5.6 on March 21, 2014 (and nearly recovered, to ~ 7 in our tentative May 26-27, 2015 data), corresponding to an e-folding time back to pre-storm opacity of 2.7 years, but the lower cloud has dropped down to the 3

  13. Making Displaced Holograms At Two Wavelengths

    NASA Technical Reports Server (NTRS)

    Witherow, William K.; Ecker, Andreas

    1989-01-01

    Two-wavelength holographic system augmented with pair of prisms to introduce small separation between holograms formed simultaneously at two wavelengths on holographic plate. Principal use in study of flows. Gradients in index of refraction of fluid caused by variations in temperature, concentration, or both. Holography at one wavelength cannot be used to distinguish between two types of variations. Difference between spacings of fringes in photographs reconstructed from holograms taken simultaneously at two different wavelengths manipulated mathematically to determine type of variation.

  14. Multiple wavelength light collimator and monitor

    NASA Technical Reports Server (NTRS)

    Gore, Warren J. (Inventor)

    2011-01-01

    An optical system for receiving and collimating light and for transporting and processing light received in each of N wavelength ranges, including near-ultraviolet, visible, near-infrared and mid-infrared wavelengths, to determine a fraction of light received, and associated dark current, in each wavelength range in each of a sequence of time intervals.

  15. Wavelength dependence of the apparent diameter of retinal blood vessels

    NASA Astrophysics Data System (ADS)

    Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

    2005-04-01

    Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column.

  16. Measurement of thin films using very long acoustic wavelengths

    NASA Astrophysics Data System (ADS)

    Clement, G. T.; Nomura, H.; Adachi, H.; Kamakura, T.

    2013-12-01

    A procedure for measuring material thickness by means of necessarily long acoustic wavelengths is examined. The approach utilizes a temporal phase lag caused by the impulse time of wave momentum transferred through a thin layer that is much denser than its surrounding medium. In air, it is predicted that solid or liquid layers below approximately 1/2000 of the acoustic wavelength will exhibit a phase shift with an arctangent functional dependence on thickness and layer density. The effect is verified for thin films on the scale of 10 μm using audible frequency sound (7 kHz). Soap films as thin as 100 nm are then measured using 40 kHz air ultrasound. The method's potential for imaging applications is demonstrated by combining the approach with near-field holography, resulting in reconstructions with sub-wavelength resolution in both the depth and lateral directions. Potential implications at very high and very low acoustic frequencies are discussed.

  17. Sub-microsecond wavelength stabilization of tunable lasers with the internal wavelength locker

    NASA Astrophysics Data System (ADS)

    Kimura, Ryoga; Tatsumoto, Yudai; Sakuma, Kazuki; Onji, Hirokazu; Shimokozono, Makoto; Ishii, Hiroyuki; Kato, Kazutoshi

    2016-08-01

    We proposed a method of accelerating the wavelength stabilization after wavelength switching of the tunable distributed amplification-distributed feedback (TDA-DFB) laser using the internal wavelength locker to reduce the size and the cost of the wavelength control system. The configuration of the wavelength stabilization system based on this locker was as follows. At the wavelength locker, the light intensity after an optical filter is detected as a current by the photodiodes (PDs). Then, for estimating the wavelength, the current is processed by the current/voltage-converting circuit (IVC), logarithm amplifier (Log Amp) and field programmable gate array (FPGA). Finally, the laser current is tuned to the desired wavelength with reference to the estimated wavelength. With this control system the wavelength is stabilized within 800 ns after wavelength switching, which is even faster than that with the conventional control system.

  18. Retinal spot size with wavelength

    NASA Astrophysics Data System (ADS)

    Rockwell, Benjamin A.; Hammer, Daniel X.; Kennedy, Paul K.; Amnotte, Rodney E.; Eilert, Brent; Druessel, Jeffrey J.; Payne, Dale J.; Phillips, Shana L.; Stolarski, David J.; Noojin, Gary D.; Thomas, Robert J.; Cain, Clarence P.

    1997-06-01

    We have made an indirect in-vivo determination of spot size focusing in the rhesus monkey model. Measurement of the laser induced breakdown threshold both in-vitro and in-vivo allow correlation and assignment of a spot size after focusing through the living eye. We discuss and analyze the results and show how trends in minimum visible lesion data should be assessed in light of chromatic aberration. National laser safety standards are based on minimal visual lesion (MVL) threshold studies in different animal models. The energy required for a retinal lesion depends upon may parameters including wavelength and retinal spot size. We attempt to explain trends in reported MVL threshold studies using a model of the eye which allows calculation of changes in retinal spot size due to chromatic aberration.

  19. Bolometric Arrays for Millimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    Castillo, E.; Serrano, A.; Torres-Jácome, A.

    2009-11-01

    During last years, semiconductor bolometers using thin films have been developed at INAOE, specifically boron-doped hydrogenated amorphous silicon films. The characteristics shown by these devices made them attractive to be used in astronomical instrumentation, mainly in two-dimentional arrays. These detector arrays used at the Large Millimeter Telescope will make possible to obtain astronomical images in millimeter and sub-millimeter wavelengths. With this in mind, we are developing a method to produce, with enough reliability, bolometer arrays at INAOE. Until now, silicon nitride diaphragm arrays, useful as radiation absorbers, have succesfully been obtained. Sizes going from one to four millimeter by element in a consistent way; however we have not tested thermometers and metallic contact deposition yet. At the same time, we are working on two possible configurations for the readout electronics; one of them using commercial components while the other will be an integrated circuit specifically designed for this application. Both versions will work below 77K.

  20. Optimized wavelength selection for molecular absorption thermometry.

    PubMed

    An, Xinliang; Caswell, Andrew W; Lipor, John J; Sanders, Scott T

    2015-04-01

    A differential evolution (DE) algorithm is applied to a recently developed spectroscopic objective function to select wavelengths that optimize the temperature precision of water absorption thermometry. DE reliably finds optima even when many-wavelength sets are chosen from large populations of wavelengths (here 120 000 wavelengths from a spectrum with 0.002 cm(-1) resolution calculated by 16 856 transitions). Here, we study sets of fixed wavelengths in the 7280-7520 cm(-1) range. When optimizing the thermometer for performance within a narrow temperature range, the results confirm that the best temperature precision is obtained if all the available measurement time is split judiciously between the two most temperature-sensitive wavelengths. In the wide temperature range case (thermometer must perform throughout 280-2800 K), we find (1) the best four-wavelength set outperforms the best two-wavelength set by an average factor of 2, and (2) a complete spectrum (all 120 000 wavelengths from 16 856 transitions) is 4.3 times worse than the best two-wavelength set. Key implications for sensor designers include: (1) from the perspective of spectroscopic temperature sensitivity, it is usually sufficient to monitor two or three wavelengths, depending on the sensor's anticipated operating temperature range; and (2) although there is a temperature precision penalty to monitoring a complete spectrum, that penalty may be small enough, particularly at elevated pressure, to justify the complete-spectrum approach in many applications.

  1. Multi-wavelength narrow linewidth fiber laser based on distributed feedback fiber lasers

    NASA Astrophysics Data System (ADS)

    Lv, Jingsheng; Qi, Haifeng; Song, Zhiqiang; Guo, Jian; Ni, Jiasheng; Wang, Chang; Peng, Gangding

    2016-09-01

    A narrow linewidth laser configuration based on distributed feedback fiber lasers (DFB-FL) with eight wavelengths in the international telecommunication union (ITU) grid is presented and realized. In this laser configuration, eight phase-shifted gratings in series are bidirectionally pumped by two 980-nm laser diodes (LDs). The final laser output with over 10-mW power for each wavelength can be obtained, and the maximum power difference within eight wavelengths is 1.2 dB. The laser configuration with multiple wavelengths and uniform power outputs can be very useful in large scaled optical fiber hydrophone fields.

  2. A ten-year surveillance study of carbapenemase-producing Klebsiella pneumoniae in a tertiary care Greek university hospital: predominance of KPC- over VIM- or NDM-producing isolates.

    PubMed

    Spyropoulou, Aikaterini; Papadimitriou-Olivgeris, Matthaios; Bartzavali, Christina; Vamvakopoulou, Sophia; Marangos, Markos; Spiliopoulou, Iris; Anastassiou, Evangelos D; Christofidou, Myrto

    2016-03-01

    Resistance patterns and carbapenemase gene presence among Klebsiella pneumoniae isolates from the University General Hospital of Patras, Greece during a ten-year period were analysed under a surveillance programme for multi-drug-resistant bacteria. From 2005 to 2014, K. pneumoniae isolates from clinically significant specimens were identified by the Vitek 2 Advanced Expert System. Antibiotic susceptibility testing was performed by the agar disc diffusion method and Etest. The strains were tested for the presence of blaVIM, blaIMP, blaKPC, blaNDM and blaOXA-48 genes by PCR. PFGE of chromosomal Xbal DNA digests was performed. A total of 3449 K. pneumoniae isolates were recovered during the last decade. Among them, 1668 (48 %) were carbapenemase-producing: 1333 (80%) K. pneumoniae carbapenemase (KPC)-, 286 (17%) Verona imipenemase (VIM), 45 (3%) KPC- and VIM-, and four New Delhi metallo-beta-lactamase (NDM)-producing. Their resistance rates to gentamicin, colistin and tigecycline were 41%, 23% and 16%, respectively. VIM-producing K. pneumoniae were isolated in 2005 and since 2008 have been endemic. KPC-producing K. pneumoniae (KPC-Kp) isolates were introduced in 2008 and until now represent the predominant carbapenemase-producing K. pneumoniae in our institution. PFGE of 97 KPC-Kp strains identified three types: A, 84 (87%); B, 11 (11%); and E, two (2%). Eleven co-producing KPC and VIM K. pneumoniae isolates belonged to PFGE B. The four NDM-positives were classified to type F. The number of K. pneumoniae bacteraemias increased during the study period, which may be solely attributed to the increase of carbapenemase-producing isolates. The threat of carbapenemase-producing K. pneumoniae emphasizes the urgent need for implementation of infection control measures and budgetary allocations to infection control.

  3. Introducing sub-wavelength pixel THz camera for the understanding of close pixel-to-wavelength imaging challenges

    NASA Astrophysics Data System (ADS)

    Bergeron, A.; Marchese, L.; Bolduc, M.; Terroux, M.; Dufour, D.; Savard, E.; Tremblay, B.; Oulachgar, H.; Doucet, M.; Le Noc, L.; Alain, C.; Jerominek, H.

    2012-06-01

    Conventional guidelines and approximations useful in macro-scale system design can become invalidated when applied to the smaller scales. An illustration of this is when camera pixel size becomes smaller than the diffraction-limited resolution of the incident light. It is sometimes believed that there is no benefit in having a pixel width smaller than the resolving limit defined by the Raleigh criterion, 1.22 λ F/#. Though this rarely occurs in today's imaging technology, terahertz (THz) imaging is one emerging area where the pixel dimensions can be made smaller than the imaging wavelength. With terahertz camera technology, we are able to achieve sub-wavelength pixel sampling pitch, and therefore capable of directly measuring if there are image quality benefits to be derived from sub-wavelength sampling. Interest in terahertz imaging is high due to potential uses in security applications because of the greater penetration depth of terahertz radiation compared to the infrared and the visible. This paper discusses the modification by INO of its infrared MEMS microbolometer detector technology toward a THz imaging platform yielding a sub-wavelength pixel THz camera. Images obtained with this camera are reviewed in this paper. Measurements were also obtained using microscanning to increase sampling resolution. Parameters such as imaging resolution and sampling are addressed. A comparison is also made with results obtained with an 8-12 μm band camera having a pixel pitch close to the diffractionlimit.

  4. Fiber-optic current sensor with self-compensation of source wavelength changes.

    PubMed

    Müller, G M; Quan, W; Lenner, M; Yang, L; Frank, A; Bohnert, K

    2016-06-15

    We demonstrate a method for self-compensation of scale factor changes of an interferometric fiber-optic current sensor caused by source wavelength shifts, e.g., due to changes in source temperature or drive current. An adequately tailored fiber-optic retarder in the optical circuit introduces wavelength-dependent mixing of the orthogonal polarization modes of the sensor. The resulting change in scale factor balances the variation of the Faraday effect with wavelength. The wavelength dependence of the sensor is suppressed by more than an order of magnitude to <0.2% over wavelength spans of at least 10 nm around 1305 nm. The retarder is designed as an athermal device for operation between -40°C and 80°C. PMID:27304309

  5. A new method for fiber Bragg grating wavelength demodulation with calibration

    NASA Astrophysics Data System (ADS)

    Fu, Jian-wei; Xiao, Li-zhi; Zhang, Yuan-zhong; Zhao, Xiao-liang; Chen, Hai-feng

    2006-01-01

    A wavelength calibration method is proposed to improve Fiber Bragg Grating (FBG) Wavelength detection precision. The reflected spectra of two reference FBG elements and a sensing FBG element are scanned by narrow band light from a fiber F-P tunable filter (FFP-TF) driven by triangular waveform voltage. Sequence numbers of FBG and peak position of spectra are identified with full spectrum analysis. Two reference FBG elements with fixed wavelength are used to monitor the transmission wavelength of filter and to construct the relationship between wavelength and the driving voltage, the driving voltage of the sensing FBG spectrum peak is scaled as the Bragg wavelength with the linear interpolation method. In the temperature experiment, three peak-seek methods such as centroid method, differential method and Gaussian-fit method are introduced and the temperature measurement precisions of +/-1C °,+/-0.5C ° and +/-0.3C ° are achieved respectively, corresponding to the wavelength error of +/-10pm, +/-5pm and +/-3pm. Finally, multipoint FBG sensing system is accomplished with calibration and wavelength measurement precisions of +/-10pm is obtained. The experimental results shows that the new method can reduce the wavelength measurement error caused by nonlinearity in piezoelectric transducer (PZT) response and wavelength drift due to PZT hysteresis.

  6. Radar scattering laws and wavelength dependence of the lunar surface

    NASA Technical Reports Server (NTRS)

    Simpson, R. A.

    1978-01-01

    Data from Apollo lunar bistatic radar experiments have been processed to give probability density functions for surface slopes. These show best agreement with a Hagfors scattering law, though data having both gaussian and exponential characteristics also exist. Surface roughness estimates range from 4 deg in maria to at least 8 deg in highlands, values which are appropriate to 25 m horizontal scales and which are areal averages over tens of square kilometers. Roughness varies with wavelength, most strongly in maria.

  7. Wavelength Anomalies in UV-Vis Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Tellinghuisen, J.

    2012-06-01

    Commercial spectrophotometers are great tools for recording absorption spectra of low-to-moderate resolution and high photometic quality. However, in the case of at least one such instrument, the Shimadzu UV-2101PC (and by assumption, similar Shimadzu models), the wavelength accuracy may not match the photometric accuracy. In fact the wavelength varies with slit width, spectral sampling interval, and even the specified range, with a smoothing algorithm invoked any time the spectrum includes more than 65 sampled wavelengths. This behavior appears not to be documented anywhere, but it has been present for at least 20 years and persists even in the latest software available to run the instrument. The wavelength shifts can be as large as 1 nm, so for applications where wavelength accuracy better than this is important, wavelength calibration must be done with care to ensure that the results are valid for the parameters used to record the target spectra.

  8. The Fine-Structure Constant and Wavelength Calibration

    NASA Astrophysics Data System (ADS)

    Whitmore, Jonathan

    The fine-structure constant is a fundamental constant of the universe--and widely thought to have an unchanging value. However, the past decade has witnessed a controversy unfold over the claimed detection that the fine-structure constant had a different value in the distant past. These astrophysical measurements were made with spectrographs at the world's largest optical telescopes. The spectrographs make precise measurements of the wavelength spacing of absorption lines in the metals in the gas between the quasar background source and our telescopes on Earth. The wavelength spacing gives a snapshot of the atomic physics at the time of the interaction. Whether the fine-structure constant has changed is determined by comparing the atomic physics in the distant past with the atomic physics of today. We present our contribution to the discussion by analyzing three nights data taken with the HIRES instrument (High Resolution Echelle Spectrograph) on the Keck telescope. We provide an independent measurement on the fine-structure constant from the Damped Lyman alpha system at a redshift of z =2.309 (10.8 billion years ago) quasar PHL957. We developed a new method for calibrating the wavelength scale of a quasar exposure to a much higher precision than previously achieved. In our subsequent analysis, we discovered unexpected wavelength calibration errors that has not been taken into account in the previously reported measurements. After characterizing the wavelength miscalibrations on the Keck-HIRES instrument, we obtained several nights of data from the main competing instrument, the VLT (Very Large Telescope) with UVES (Ultraviolet and Visual Echelle Spectrograph). We applied our new wavelength calibration method and uncovered similar in nature systematic errors as found on Keck-HIRES. Finally, we make a detailed Monte Carlo exploration of the effects that these miscalibrations have on making precision fine-structure constant measurements.

  9. Laser wavelength meter: analysis of measurement uncertainties

    NASA Astrophysics Data System (ADS)

    Skrzeczanowski, Wojciech; Zyczkowski, Marek; Dlugaszek, Andrzej

    1999-08-01

    Principle of operation of laser radiation wavelength meter based on Fabry-Perot interferometer and linear CCD camera is presented in the paper. A dependence, on the base of which laser wavelength can be calculated, is found and a way of defining of all component uncertainties of a measurement is shown. An analysis of an influence and examples of definition of uncertainties of a measurement for four wavelength meter structural sets of different objective focal lengths are presented.

  10. Wavelength-doubling optical parametric oscillator

    DOEpatents

    Armstrong, Darrell J.; Smith, Arlee V.

    2007-07-24

    A wavelength-doubling optical parametric oscillator (OPO) comprising a type II nonlinear optical medium for generating a pair of degenerate waves at twice a pump wavelength and a plurality of mirrors for rotating the polarization of one wave by 90 degrees to produce a wavelength-doubled beam with an increased output energy by coupling both of the degenerate waves out of the OPO cavity through the same output coupler following polarization rotation of one of the degenerate waves.

  11. A preliminary mechanical property and stress corrosion evaluation of VIM-VAR work strengthened and direct aged Inconel 718 bar material

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1987-01-01

    This report presents a preliminary mechanical property and stress corrosion evaluation of double melted (vacuum induction melted (VIM), and vacuum arc remelted (VAR)), solution treated, work strengthened and direct aged Inconel 718 alloy bar (5.50 in. (13.97 cm) diameter). Two sets of tensile specimens, one direct single aged and the other direct double aged, were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 200 ksi (1378.96 MPa) and 168 ksi (1158.33 MPa), respectively, were realized at ambient temperature, for the direct double aged specimen. No failures occurred in the single or double edged longitudinal and transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test showed no mechanical property degradation.

  12. On the wavelength of self-organized shoreline sand waves

    NASA Astrophysics Data System (ADS)

    Falqués, A.; van den Berg, N.; Ribas, F.; Caballeria, M.; Calvete, D.

    2012-04-01

    Shoreline sand waves are undulations of the shoreline that extend into the bathymetry up to a certain depth. Here we will focus on self-organized sand waves that form due to shoreline instability in case of very oblique wave incidence (Ashton et al., 2001). The model of Ashton and co-authors did not predict any wavelength selection for the emerging sand waves whereas Falqués and Calvete (2005) predicted a wavelength selection in the range 4-15 km. This difference is attributable to that Falqués and Calvete (2005) computed wave refraction and shoaling over the actual curvilinear depth contours while Ashton et al. (2001) assumed locally rectilinear and parallel contours. Although there exist shoreline features at a larger scale (Ashton et al. 2001; Falqués et al. 2011) sand waves at a few km scale are more common (Ruessink and Jeuken, 2002; Davidson-Arnott and van Heyningen, 2003; Falqués et al., 2011; Medellin et al., 2008) . While their characteristic wavelength is a robust model output (Falqués and Calvete, 2005; Uguccioni et al., 2006; van den Berg et al., 2011) the physical reasons for the existence of a wavelength selection are still unknown. Furthermore, the parameter dependence of the dominant wavelength, Lm, is largely unexplored. In particular, the disparity between the large length scale of sand waves and the relevant length scales of the problem: width of the surf zone, water wave wavelength, etc. is intriguing. The aim of the present contribution is to gain insight into those physical reasons and the dependence of Lm on beach profile and water wave properties. The essence of sandwave behaviour can be captured with the simple one-line shoreline modelling concept by looking at the alongshore position of the maximum in total transport rate Q, which is here investigated with both the linearized model of Falqués and Calvete (2005) and the nonlinear model of van den Berg et al. (2011) . It is found that the position of that maximum is largely controlled

  13. Optimizing constant wavelength neutron powder diffractometers

    NASA Astrophysics Data System (ADS)

    Cussen, Leo D.

    2016-06-01

    This article describes an analytic method to optimize constant wavelength neutron powder diffractometers. It recasts the accepted mathematical description of resolution and intensity in terms of new variables and includes terms for vertical divergence, wavelength and some sample scattering effects. An undetermined multiplier method is applied to the revised equations to minimize the RMS value of resolution width at constant intensity and fixed wavelength. A new understanding of primary spectrometer transmission (presented elsewhere) can then be applied to choose beam elements to deliver an optimum instrument. Numerical methods can then be applied to choose the best wavelength.

  14. Effective wavelength for multicolor/pyrometry.

    PubMed

    Gardner, J L

    1980-09-15

    The concept of a temperature varying effective wavelength has recently been applied in multiwavelength pyrometry. The effective wavelength is shown to be discontinuous at a particular temperature, and the properties of the effective wavelength over a wide temperature range are explained. It is shown that a simple relationship is sufficient to calculate the effective wavelength and hence radiance at a given temperature without resorting to a convolution integration, in particular where broad filters are used to improve signal levels in a pyrometer. PMID:20234565

  15. Prevalence of bla NDM, bla PER, bla VEB, bla IMP, and bla VIM Genes among Acinetobacter baumannii Isolated from Two Hospitals of Tehran, Iran.

    PubMed

    Fallah, Fatemeh; Noori, Maryam; Hashemi, Ali; Goudarzi, Hossein; Karimi, Abdollah; Erfanimanesh, Soroor; Alimehr, Shadi

    2014-01-01

    Background and Objectives. The aim of this study was to determine the frequency of bla NDM, bla PER, bla VEB, bla IMP, and bla VIM type genes among A. baumannii isolates from hospitalized patients in two hospitals in Tehran, Iran. Patients and Methods. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and Broth microdilution methods. The frequency of MBL (metallo-beta-lactamase) and ESBL (extended-spectrum-beta-lactamase) producers was evaluated by CDDT. The β -lactamases genes were detected by PCR and sequencing methods. Results. The resistance of A. baumannii isolates against tested antibiotics was as follows: 103 (95.4%) to ceftazidime, 108 (100%) to cefotaxime, 105 (95.7%) to cefepime, 99 (91.7%) to imipenem, 99 (91.7%) to meropenem, 87 (80.6%) to amikacin, 105 (97.2%) to piperacillin, 100 (92.6%) to ciprofloxacin, 103 (95.4%) to piperacillin/tazobactam, 44 (40.7%) to gentamicin, 106 (98.1%) to ampicillin/sulbactam, 106 (98.1%) to co-trimoxazole, 87 (80.6%) to tetracycline, and 1 (1.8%) to colistin. Using combined disk diffusion test, 91 (84.2%) and 86 (86.86%) were ESBL and MBL producers, respectively. The prevalence of bla PER-1, bla VEB-1, bla IMP-1, and bla VIM-1 genes was 71 (78.03%), 36 (39.5%), 3 (3.48%), and 15 (17.44%), respectively. Conclusions. The prevalence of ESBLs and MBLs-producing A. baumannii strains detected in this study is a major concern and highlights the need of infection control measures.

  16. Extensively Drug-Resistant Pseudomonas aeruginosa Isolates Containing blaVIM-2 and Elements of Salmonella Genomic Island 2: a New Genetic Resistance Determinant in Northeast Ohio

    PubMed Central

    Perez, Federico; Hujer, Andrea M.; Marshall, Steven H.; Ray, Amy J.; Rather, Philip N.; Suwantarat, Nuntra; Dumford, Donald; O'Shea, Patrick; Domitrovic, T. Nicholas J.; Salata, Robert A.; Chavda, Kalyan D.; Chen, Liang; Kreiswirth, Barry N.; Vila, Alejandro J.; Haussler, Susanne; Jacobs, Michael R.

    2014-01-01

    Carbapenems are a mainstay of treatment for infections caused by Pseudomonas aeruginosa. Carbapenem resistance mediated by metallo-β-lactamases (MBLs) remains uncommon in the United States, despite the worldwide emergence of this group of enzymes. Between March 2012 and May 2013, we detected MBL-producing P. aeruginosa in a university-affiliated health care system in northeast Ohio. We examined the clinical characteristics and outcomes of patients, defined the resistance determinants and structure of the genetic element harboring the blaMBL gene through genome sequencing, and typed MBL-producing P. aeruginosa isolates using pulsed-field gel electrophoresis (PFGE), repetitive sequence-based PCR (rep-PCR), and multilocus sequence typing (MLST). Seven patients were affected that were hospitalized at three community hospitals, a long-term-care facility, and a tertiary care center; one of the patients died as a result of infection. Isolates belonged to sequence type 233 (ST233) and were extensively drug resistant (XDR), including resistance to all fluoroquinolones, aminoglycosides, and β-lactams; two isolates were nonsusceptible to colistin. The blaMBL gene was identified as blaVIM-2 contained within a class 1 integron (In559), similar to the cassette array previously detected in isolates from Norway, Russia, Taiwan, and Chicago, IL. Genomic sequencing and assembly revealed that In559 was part of a novel 35-kb region that also included a Tn501-like transposon and Salmonella genomic island 2 (SGI2)-homologous sequences. This analysis of XDR strains producing VIM-2 from northeast Ohio revealed a novel recombination event between Salmonella and P. aeruginosa, heralding a new antibiotic resistance threat in this region's health care system. PMID:25070102

  17. Quantitative comparison of wavelength dependence on penetration depth and imaging contrast for ultrahigh-resolution optical coherence tomography using supercontinuum sources at five wavelength regions

    NASA Astrophysics Data System (ADS)

    Ishida, S.; Nishizawa, N.

    2012-01-01

    Optical coherence tomography (OCT) is a non invasive optical imaging technology for micron-scale cross-sectional imaging of biological tissue and materials. We have been investigating ultrahigh resolution optical coherence tomography (UHR-OCT) using fiber based supercontinuum sources. Although ultrahigh longitudinal resolution was achieved in several center wavelength regions, its low penetration depth is a serious limitation for other applications. To realize ultrahigh resolution and deep penetration depth simultaneously, it is necessary to choose the proper wavelength to maximize the light penetration and enhance the image contrast at deeper depths. Recently, we have demonstrated the wavelength dependence of penetration depth and imaging contrast for ultrahigh resolution OCT at 0.8 μm, 1.3 μm, and 1.7 μm wavelength ranges. In this paper, additionally we used SC sources at 1.06 μm and 1.55 μm, and we have investigated the wavelength dependence of UHR-OCT at five wavelength regions. The image contrast and penetration depth have been discussed in terms of the scattering coefficient and water absorption of samples. Almost the same optical characteristics in longitudinal and lateral resolution, sensitivity, and incident optical power at all wavelength regions were demonstrated. We confirmed the enhancement of image contrast and decreased ambiguity of deeper epithelioid structure at longer wavelength region.

  18. The universe at infrared wavelengths

    NASA Technical Reports Server (NTRS)

    Beichman, C. A.

    1988-01-01

    This article discusses the status of infrared astronomy after the mission of the Infrared Astronomical Satellite (IRAS). Important scientific results from IRAS include: the origin of the interplanetary dust cloud, the formation of solar type stars, the energetics of the interstellar medium, the discovery of ultra-luminous infrared galaxies and their possible relation to the origin of quasars, and the large scale structure of the universe.

  19. Semiconductor laser with multiple lasing wavelengths

    DOEpatents

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-07-29

    A new class of multi-terminal vertical-cavity semiconductor laser components has been developed. These multi-terminal laser components can be switched, either electrically or optically, between distinct lasing wavelengths, or can be made to lase simultaneously at multiple wavelengths.

  20. Optical wavelength modulation in free electron lasers

    SciTech Connect

    Mabe, R.M.; Wong, R.K.; Colson, W.B.

    1995-12-31

    An attribute of the free electron laser (FEL) is the continuous tunability of the optical wavelength by modulation of the electron beam energy. The variation of the wavelength and power of the optical beam is studied as a function of FEL operating parameters. These results will be applied to the Stanford SCA FEL and Boeing FEL.

  1. Evaluation of clonality and carbapenem resistance mechanisms among Acinetobacter baumannii-Acinetobacter calcoaceticus complex and Enterobacteriaceae isolates collected in European and Mediterranean countries and detection of two novel β-lactamases, GES-22 and VIM-35.

    PubMed

    Castanheira, Mariana; Costello, Sarah E; Woosley, Leah N; Deshpande, Lalitagauri M; Davies, Todd A; Jones, Ronald N

    2014-12-01

    We evaluated doripenem-resistant Acinetobacter baumannii-Acinetobacter calcoaceticus complex (ACB; n = 411) and Enterobacteriaceae (n = 92) isolates collected from patients from 14 European and Mediterranean countries during 2009 to 2011 for the presence of carbapenemase-encoding genes and clonality. Following susceptibility testing, carbapenem-resistant (doripenem MIC, >2 μg/ml) isolates were screened for carbapenemases. New β-lactamase genes were expressed in a common background and susceptibility was tested. Class 1 integrons were sequenced. Clonality was evaluated by pulsed-field gel electrophoresis and multilocus sequence typing (Pasteur scheme). Relative expression of β-lactam intrinsic resistance mechanisms was determined for carbapenemase-negative Enterobacteriaceae. ACB and Enterobacteriaceae displayed 58.9 and 0.9% doripenem resistance, respectively. bla(OXA-23), bla(OXA-58), and bla(OXA-24/OXA-40) were detected among 277, 77, and 29 ACB, respectively (in 8, 6, and 5 countries). Ten Turkish isolates carried bla(GES-11) or bla(GES-22). GES-22 (G243A and M169L mutations in GES-1) had an extended-spectrum β-lactamase profile. A total of 33 clusters of ≥ 2 ACB isolates were observed, and 227 isolates belonged to sequence type 2/international clone II. Other international clones were limited to Turkey and Israel. Doripenem-resistant Enterobacteriaceae increased significantly (0.7 to 1.6%), and 15 blaKPC-2- and 22 blaKPC-3-carrying isolates, mostly belonging to clonal complexes 11 and 258, were observed. Enterobacteriaceae isolates producing OXA-48 (n = 16; in Turkey and Italy), VIM-1 (n = 10; in Greece, Poland, and Spain), VIM-26 (n = 1; in Greece), and IMP-19, VIM-4, and the novel VIM-35 (n = 1 each from Poland) were detected. VIM-35 had one substitution compared to VIM-1 (A235T) and a similar susceptibility profile. One or more resistance mechanisms were identified in 4/6 carbapenemase-negative Enterobacteriaceae. This broad evaluation confirms results

  2. GHRS Cycle 5 Echelle Wavelength Monitor

    NASA Astrophysics Data System (ADS)

    Soderblom, David

    1995-07-01

    This proposal defines the spectral lamp test for Echelle A. It is an internal test which makes measurements of the wavelength lamp SC2. It calibrates the carrousel function, Y deflections, resolving power, sensitivity, and scattered light. The wavelength calibration dispersion constants will be updated in the PODPS calibration data base. This proposal defines the spectral lamp test for Echelle B. It is an internal test which makes measurements of the wavelength lamp SC2. It calibrates the carrousel function, Y deflections, resolving power, sensitivity, and scattered light. The wavelength calibration dispersion constants will be updated in the PODPS calibration data base. It will be run every 4 months. The wavelengths may be out of range according to PEPSI or TRANS. Please ignore the errors.

  3. Mars: Wavelength-dependent dual polarization global scattering

    NASA Technical Reports Server (NTRS)

    Harmon, J. K.; Slade, M. A.; Hudson, R. S.

    1992-01-01

    During the 1988 and 1990 Mars oppositions, the first continuous-wave (CW) multi-wavelength radar observations were performed that include the entire echo in both polarizations. These observations, coordinated in subradar coverage when possible, were made with the Arecibo S-band (12.6 cm lambda) and Goldstone X-band (3.5 cm lambda) facilities. The CW spectra obtained during these oppositions have been studied using a variety of techniques to explore the spatial and wavelength dependence of both the Same-sense Circular (SC) and Opposite-sense Circular (OC) polarization returns. Earlier multi-wavelength comparisons dealt primarily with the quasispecular component of the echoes. Our work in contrast has much new information (at high signal-to-noise) for the SC 'depolarized component. The unique value of these radar observations lies in their potential for probing the subsurface scattering behavior in 'appropriate' terrain. The clearest case for wavelength dependence in the SC component is the scattering behavior over Tharsis, where the X-band features are significantly weaker than the S-band features. This hypothesis was advanced to account for the low thermal inertia of Tharsis, but also can explain the S/X differences if the layer is about 40 cm thick. In contrast to the Tharsis result, the depolarized echo from the heavily cratered terrain is actually stronger at X-band. The obvious interpretation is that more scatterers exist at the scale of the shorter wavelength, either at the surface or as a distributed subsurface scatterers. The strongest depolarized feature of the X-band spectra is associated with the south residual polar cap. The radar cross section of this feature corresponds to an equivalent full-disk albedo of unity.

  4. THE CIRCULAR POLARIZATION OF SAGITTARIUS A* AT SUBMILLIMETER WAVELENGTHS

    SciTech Connect

    Munoz, D. J.; Moran, J. M.; Marrone, D. P.; Rao, R.

    2012-02-01

    We report the first detections of circularly polarized emission at submillimeter wavelengths from the compact radio source and supermassive black hole candidate Sgr A* at a level of 1.2% {+-} 0.3% at 1.3 mm wavelength (230 GHz) and 1.6% {+-} 0.3% at 860 {mu}m (345 GHz) with the same handedness, left circular polarization (LCP), as observed at all lower frequencies (1.4-15 GHz). The observations, taken with the Submillimeter Array in multiple epochs, also show simultaneous linear polarization (LP) at both wavelengths of about 6%. These properties differ sharply from those at wavelengths longer than 1 cm (frequencies below 30 GHz), where weak circular polarization (CP) ({approx}0.5%) dominates over LP, which is not detected at similar fractional limits. We describe an extensive set of tests to ensure the accuracy of our measurements. We find no CP in any other source, including the bright quasar 1924-292, which traces the same path on the sky as Sgr A* and therefore should be subject to identical systematic errors originating in the instrument frame. Since a relativistic synchrotron plasma is expected to produce little CP, the observed CP is probably generated close to the event horizon by the Faraday conversion process. We use a simple approximation to show that the phase shift associated with Faraday conversion can be nearly independent of frequency, a sufficient condition to make the handedness of CP independent of frequency. Because the size of the {tau} = 1 surface changes by more than an order of magnitude between 1.4 and 345 GHz, the magnetic field must be coherent over such scales to consistently produce LCP. To improve our understanding of the environment of SgrA* critical future measurements includes determining whether the Faraday rotation deviates from a {lambda}{sup 2} dependence in wavelength and whether the circular and linear components of the flux density are correlated.

  5. Wavelengths effective in induction of malignant melanoma

    SciTech Connect

    Setlow, R.B.; Grist, E.; Thompson, K.; Woodhead, A.D. )

    1993-07-15

    It is generally agreed that sunlight exposure is one of the etiologic agents in malignant melanoma of fair-skinned individuals. However, the wavelengths responsible for tumorigenesis are not known, although DNA is assumed to be the target because individuals defective in the repair of UV damage to DNA are several thousandfold more prone to the disease than the average population. Heavily pigmented back-cross hybrids of the genus Xiphophorus (platyfish and swordtails) are very sensitive to melanoma induction by single exposures to UV. The authors irradiated groups of five 6-day-old fish with narrow wavelength bands at 302, 313, 365, 405, and 436 nm and score the irradiated animals for melanomas 4 months later. They used several exposures at each wavelength to obtain estimates of the sensitivity for melanoma induction as a function of exposure and wavelength. The action spectrum (sensitivity per incident photon as a function of wavelength) for melanoma induction shows appreciable sensitivity at 365, 405, and probably 436 nm, suggesting that wavelengths not absorbed directly in DNA are effective in induction. They interpret the results as indicating that light energy absorbed in melanin is effective in inducing melanomas in this animal model and that, in natural sunlight, 90-95% of melanoma induction may be attributed to wavelengths >320 nm-the UV-A and visible spectral regions. 25 refs., 4 figs., 1 tab.

  6. Short wavelength FELs using the SLAC linac

    SciTech Connect

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops.

  7. Experimental verification of acoustic trace wavelength enhancement.

    PubMed

    Cray, Benjamin A

    2015-12-01

    Directivity is essentially a measure of a sonar array's beamwidth that can be obtained in a spherically isotropic ambient noise field; narrow array mainbeam widths are more directive than broader mainbeam widths. For common sonar systems, the directivity factor (or directivity index) is directly proportional to the ratio of an incident acoustic trace wavelength to the sonar array's physical length (which is always constrained). Increasing this ratio, by creating additional trace wavelengths for a fixed array length, will increase array directivity. Embedding periodic structures within an array generates Bragg scattering of the incident acoustic plane wave along the array's surface. The Bragg scattered propagating waves are shifted in a precise manner and create shorter wavelength replicas of the original acoustic trace wavelength. These replicated trace wavelengths (which contain identical signal arrival information) increase an array's wavelength to length ratio and thus directivity. Therefore, a smaller array, in theory, can have the equivalent directivity of a much larger array. Measurements completed in January 2015 at the Naval Undersea Warfare Center's Acoustic Test Facility, in Newport, RI, verified, near perfectly, these replicated, shorter, trace wavelengths. PMID:26723331

  8. Wavelengths Effective in Induction of Malignant Melanoma

    NASA Astrophysics Data System (ADS)

    Setlow, Richard B.; Grist, Eleanor; Thompson, Keith; Woodhead, Avril D.

    1993-07-01

    It is generally agreed that sunlight exposure is one of the etiologic agents in malignant melanoma of fair-skinned individuals. However, the wavelengths responsible for tumorigenesis are not known, although DNA is assumed to be the target because individuals defective in the repair of UV damage to DNA are several thousandfold more prone to the disease than the average population. Heavily pigmented backcross hybrids of the genus Xiphophorus (platyfish and swordtails) are very sensitive to melanoma induction by single exposures to UV. We irradiated groups of five 6-day-old fish with narrow wavelength bands at 302, 313, 365, 405, and 436 nm and scored the irradiated animals for melanomas 4 months later. We used several exposures at each wavelength to obtain estimates of the sensitivity for melanoma induction as a function of exposure and wavelength. The action spectrum (sensitivity per incident photon as a function of wavelength) for melanoma induction shows appreciable sensitivity at 365, 405, and probably 436 nm, suggesting that wavelengths not absorbed directly in DNA are effective in induction. We interpret the results as indicating that light energy absorbed in melanin is effective in inducing melanomas in this animal model and that, in natural sunlight, 90-95% of melanoma induction may be attributed to wavelengths > 320 nm-the UV-A and visible spectral regions.

  9. Multiple Wavelength Observations of Flaring Active Regions

    NASA Astrophysics Data System (ADS)

    Lang, Kenneth R.

    The radio emission of quiescent active regions at 6 cm wavelength marks the legs of magnetic dipoles, and the emission at 20 cm wavelength delineates the radio wavelength counterpart of the coronal loops previously detected at X-ray wavelengths. At both wavelengths the temperatures have coronal values of a few million degrees. The polarization of the radio emission specifies the structure and strength of the coronal magnetic field (H ≈ 600 Gauss at heights h ≈ 4 x 109 cm above sunspot umbrae). At 6 cm and 20 cm wavelength the solar bursts have angular sizes between 5" and 30", brightness temperatures between 2 x 107 K and 2 x 108 K, and degrees of circular polarization between 10% and 90%. The location of the burst energy release is specified with second-of-arc accuracy. At radio wavelengths the bursts occur within the central regions of magnetic loops, while the flaring Ha kernels are located at the loop footpoints. Coronal loops exhibit enhanced radio emission (preburst heating) a few minutes before the release of burst energy. The radio polarization data indicate magnetic changes before and during solar bursts.

  10. Experimental verification of acoustic trace wavelength enhancement.

    PubMed

    Cray, Benjamin A

    2015-12-01

    Directivity is essentially a measure of a sonar array's beamwidth that can be obtained in a spherically isotropic ambient noise field; narrow array mainbeam widths are more directive than broader mainbeam widths. For common sonar systems, the directivity factor (or directivity index) is directly proportional to the ratio of an incident acoustic trace wavelength to the sonar array's physical length (which is always constrained). Increasing this ratio, by creating additional trace wavelengths for a fixed array length, will increase array directivity. Embedding periodic structures within an array generates Bragg scattering of the incident acoustic plane wave along the array's surface. The Bragg scattered propagating waves are shifted in a precise manner and create shorter wavelength replicas of the original acoustic trace wavelength. These replicated trace wavelengths (which contain identical signal arrival information) increase an array's wavelength to length ratio and thus directivity. Therefore, a smaller array, in theory, can have the equivalent directivity of a much larger array. Measurements completed in January 2015 at the Naval Undersea Warfare Center's Acoustic Test Facility, in Newport, RI, verified, near perfectly, these replicated, shorter, trace wavelengths.

  11. Wavelength initialization employing wavelength recognition scheme in WDM-PON based on tunable lasers

    NASA Astrophysics Data System (ADS)

    Mun, Sil-Gu; Lee, Eun-Gu; Lee, Jong Hyun; Lee, Sang Soo; Lee, Jyung Chan

    2015-01-01

    We proposed a simple method to initialize the wavelength of tunable lasers in WDM-PON employing wavelength recognition scheme with an optical filter as a function of wavelength and accomplished plug and play operation. We also implemented a transceiver based on our proposed wavelength initialization scheme and then experimentally demonstrated the feasibility in WDM-PON configuration guaranteeing 16 channels with 100 GHz channel spacing. Our proposal is a cost-effective and easy-to-install method to realize the wavelength initialization of ONU. In addition, this method will support compatibility with all kind of tunable laser regardless of their structures and operating principles.

  12. Use of two wavelengths in microscopic TV holography for nondestructive testing

    NASA Astrophysics Data System (ADS)

    Upputuri, Paul Kumar; Umapathy, Somasundaram; Pramanik, Manojit; Kothiyal, Mahendra Prasad; Nandigana, Krishna Mohan

    2014-11-01

    Single wavelength TV holography is a widely used whole-field noncontacting optical method for nondestructive testing (NDT) of engineering structures. However, with a single wavelength configuration, it is difficult to quantify the large amplitude defects due to the overcrowding of fringes in the defect location. In this work, we propose a two wavelength microscopic TV holography using a single-chip color charge-coupled device (CCD) camera for NDT of microspecimens. The use of a color CCD allows simultaneous acquisition of speckle patterns at two different wavelengths and makes the data acquisition as simple as that of the single wavelength case. For the quantitative measurement of the defect, an error compensating eight-step phase-shifted algorithm is used. The design of the system and a few experimental results on small-scale rough specimens are presented.

  13. IUE data reduction: Wavelength determinations and line identifications using a VAX/750 computer

    NASA Astrophysics Data System (ADS)

    Davidson, J. P.; Bord, D. J.

    A fully automated, interactive system for determining the wavelengths of features in extracted IUE spectra is described. Wavelengths are recorded from video displays of expanded plots of individual orders using a movable cursor, and then corrected for IUE wavelength scale errors. The estimated accuracy of an individual wavelength in the final tabulation is 0.050 A. Such lists are ideally suited for line identification work using the method of wavelength coincidence statistics (WCS). The results of WCS studies of the ultraviolet spectra of the chemically peculiar (CP) stars iota Coronae Borealis and kappa Camcri. Aside from confirming a number of previously reported aspects of the abundance patterns in these stars, the searches produced some interesting, new discoveries, notably the presence of Hf in the spectrum of kappa Camcri. The implications of this work for theories designed to account for anomalous abundances in chemically peculiar stars are discussed.

  14. A novel wavelength availability advertisement based ASON routing protocol implementation

    NASA Astrophysics Data System (ADS)

    Li, Jian; Liu, Juan; Zhang, Jie; Gu, Wanyi

    2005-11-01

    operator can make a good trade off between the wavelength availability advertisement Protocol Average Overhead and Blocking Probability by adopting and adjusting the routing update triggers; and the last is that wavelength availability advertisement throughout the optical network is applicable and our ASON routing protocol implementation could be applied in ASON when its scale is not too large and if the calls do not arrive and leave the network in a too frequent pace.

  15. Engineering reverse saturable absorbers for desired wavelengths

    NASA Astrophysics Data System (ADS)

    Band, Yehuda B.; Scharf, Benjamin

    1986-06-01

    A variety of applications exist for reverse saturable absorbers (RSAs) in laser science (RSAs are substances whose excited-state absorption cross section is larger than their ground-state absorption cross section at a given wavelength and possess a number of other properties). We propose an approach to designing RSAs at a desired wavelength by construction of dimers of dye molecules which absorb near the wavelength of interest. The dimer ground-state absorption is to a state in which the excitation is spread over both monomeric units and the excited-state absorption commences from this state to the doubly excited electronic state in which both monomeric units are excited.

  16. Magic wavelengths for terahertz clock transitions

    SciTech Connect

    Zhou Xiaoji; Xu Xia; Chen Xuzong; Chen Jingbiao

    2010-01-15

    Magic wavelengths for laser trapping of boson isotopes of alkaline-earth metal atoms Sr, Ca, and Mg are investigated while considering terahertz clock transitions between the {sup 3}P{sub 0}, {sup 3}P{sub 1}, and {sup 3}P{sub 2} metastable triplet states. Our calculation shows that magic wavelengths for laser trapping do exist. This result is important because those metastable states have already been used to make accurate clocks in the terahertz frequency domain. Detailed discussions for magic wavelengths for terahertz clock transitions are given in this article.

  17. Optical amplification at the 1. 31 wavelength

    DOEpatents

    Cockroft, N.J.

    1994-02-15

    An optical amplifier operating at the 1.31 [mu]m wavelength for use in such applications as telecommunications, cable television, and computer systems is described. An optical fiber or other waveguide device is doped with both Tm[sup 3+] and Pr[sup 3+] ions. When pumped by a diode laser operating at a wavelength of 785 nm, energy is transferred from the Tm[sup 3+] ions to the Pr[sup 3+] ions, causing the Pr[sup 3+] ions to amplify at a wavelength of 1.31. 1 figure.

  18. Multimode fiber optic wavelength division multiplexing

    NASA Technical Reports Server (NTRS)

    Spencer, J. L.

    1982-01-01

    Optical wavelength division multiplexing (WDM) systems, with signals transmitted on different wavelengths through a single optical fiber, can have increased bandwidth and fault isolation properties over single wavelength optical systems. Two WDM system designs that might be used with multimode fibers are considered and a general description of the components which could be used to implement the system are given. The components described are sources, multiplexers, demultiplexers, and detectors. Emphasis is given to the demultiplexer technique which is the major developmental component in the WDM system.

  19. Long-wavelength cosmological perturbation in the Universe with multiple perfect fluids

    NASA Astrophysics Data System (ADS)

    Nambu, Yasusada; Ohokata, Shin-ichi

    2002-08-01

    We investigate large-scale cosmological perturbation in the Universe with multiple perfect fluids. Using the long-wavelength approximation with the Hamilton-Jacobi method, we derive a formula for the gauge-invariant comoving curvature perturbation. As an application of our approach, we examine large-scale perturbation in a brane cosmology.

  20. Geomorphological significance of Ontario Lacus on Titan: Integrated interpretation of Cassini VIMS, ISS and RADAR data and comparison with the Etosha Pan (Namibia)

    NASA Astrophysics Data System (ADS)

    Cornet, T.; Bourgeois, O.; Le Mouélic, S.; Rodriguez, S.; Lopez Gonzalez, T.; Sotin, C.; Tobie, G.; Fleurant, C.; Barnes, J. W.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

    2012-04-01

    Ontario Lacus is the largest lake of the whole southern hemisphere of Titan, Saturn's major moon. It has been imaged twice by each of the Cassini imaging systems (Imaging Science Subsystem (ISS) in 2004 and 2005, Visual and Infrared Mapping Spectrometer (VIMS) in 2007 and 2009 and RADAR in 2009 and 2010). We compile a geomorphological map and derive a "hydrogeological" interpretation of Ontario Lacus, based on a joint analysis of ISS, VIMS and RADAR SAR datasets, along with the T49 altimetric profile acquired in December 2008. The morphologies observed on Ontario Lacus are compared to landforms of a semi-arid terrestrial analog, which resembles Titan's lakes: the Etosha Pan, located in the Owambo Basin (Namibia). The Etosha Pan is a flat-floored depression formed by dissolution, under semi-arid conditions, of a surface evaporitic layer (calcretes) controlled by groundwater vertical motions. We infer that Ontario Lacus is an extremely flat and shallow depression lying in an alluvial plain surrounded by small mountain ranges under climatic conditions similar to those of terrestrial semi-arid regions. Channels are seen in the southern part of Ontario Lacus in VIMS and RADAR data, acquired at a 2-years time interval. Their constancy in location with time implies that the southern portion of the depression is probably not fully covered by a liquid layer at the time of the observations, and that they most probably run on the floor of the depression. A shallow layer of surface liquids, corresponding to the darkest portions of the RADAR images, would thus cover about 53% of the surface area of the depression, of which almost 70% is located in its northern part. These liquid-covered parts of the depression, where liquid ethane was previously identified, are interpreted as topographic lows where the "alkanofer" raises above the depression floor. The rest of the depression, and mostly its southern part, is interpreted as a flat and smooth exposed floor, likely composed of a

  1. Multiple wavelength photolithography for preparing multilayer microstructures

    SciTech Connect

    Dentinger, Paul Michael; Krafcik, Karen Lee

    2003-06-24

    The invention relates to a multilayer microstructure and a method for preparing thereof. The method involves first applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer. A portion of the first photodefinable composition is then exposed to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer. After exposing the first polymeric layer, a second photodefinable composition having a second exposure wavelength is applied on the first polymeric layer to form a second polymeric layer. A portion of the second photodefinable composition is then exposed to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer. In addition, a portion of each layer is removed according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portions removed.

  2. Multiple-Wavelength Pyrometry Independent Of Emissivity

    NASA Technical Reports Server (NTRS)

    Ng, Daniel

    1996-01-01

    Multiple-wavelength pyrometric method provides for determination of two sequential temperatures of same surface or temperatures of two surfaces made of same material. Temperatures measured, without knowing emissivity, by uncalibrated spectral radiometer.

  3. Controllable Dual-Wavelength Fiber Laser

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Zhou, Jun; He, Bing; Liu, Hou-Kang; Liu, Chi; Wei, Yun-Rong; Dong, Jing-Xing; Lou, Qi-Hong

    2012-07-01

    We demonstrate a controllable dual-wavelength fiber laser which contains a master laser and a slave laser. The master laser is a kind of ring cavity laser which can be injected into by the slave laser. The output laser wavelength is controlled by injected power of the slave laser; both single- and dual-wavelength operation can be achieved. Under free running, the master laser generates 1064 nm laser output. Here the slave laser is a 1072 nm fiber laser. The 1064 nm and 1072 nm laser coexist in output spectrum for relatively low injected power. Dual-wavelength and power-ratio-tunable operation can be achieved. If the injected power of the slave laser is high enough, the 1064 nm laser is extinguished automatically and there is only 1072 nm laser output.

  4. Wavelength mismatch effect in electromagnetically induced absorption

    NASA Astrophysics Data System (ADS)

    Bharti, Vineet; Wasan, Ajay; Natarajan, Vasant

    2016-07-01

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch-near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers.

  5. Grating cavity dual wavelength dye laser.

    PubMed

    Zapata-Nava, Oscar Javier; Rodríguez-Montero, Ponciano; Iturbe-Castillo, M David; Treviño-Palacios, Carlos Gerardo

    2011-02-14

    We report simultaneous dual wavelength dye laser emission using Littman-Metcalf and Littrow cavity configurations with minimum cavity elements. Dual wavelength operation is obtained by laser operation in two optical paths inside the cavity, one of which uses reflection in the circulating dye cell. Styryl 14 laser dye operating in the 910 nm to 960 nm was used in a 15%:85% PC/EG solvent green pumped with a Q-switched doubled Nd3+:YAG laser. PMID:21369171

  6. Observations of Venus at 1-meter wavelength

    NASA Astrophysics Data System (ADS)

    Butler, Bryan J.

    2014-11-01

    Radio wavelength observations of Venus (including from the Magellan spacecraft) have been a powerful method of probing its surface and atmosphere since the 1950's. The emission is generally understood to come from a combination of emission and absorption in the subsurface, surface, and atmosphere at cm and shorter wavelengths [1]. There is, however, a long-standing mystery regarding the long wavelength emission from Venus. First discovered at wavelengths of 50 cm and greater [2], the effect was later confirmed to extend to wavelengths as short as 13 cm [1,3]. The brightness temperatures are depressed significantly 50 K around 10-20 cm, increasing to as much as 200 K around 1 m) from what one would expect from a "normal" surface (e.g., similar to the Moon or Earth) [1-3].No simple surface and subsurface model of Venus can reproduce these large depressions in the long wavelength emission [1-3]. Simple atmospheric and ionospheric models fail similarly. In an attempt to constrain the brightness temperature spectrum more fully, new observations have been made at wavelengths that cover the range 60 cm to 1.3 m at the Very Large Array, using the newly available low-band receiving systems there [4]. The new observations were made over a very wide wavelength range and at several Venus phases, with that wide parameter space coverage potentially allowing us to pinpoint the cause of the phenomenon. The observations and potential interpretations will be presented and discussed.[1] Butler et al. 2001, Icarus, 154, 226. [2] Schloerb et al. 1976, Icarus, 29, 329; Muhleman et al. 1973, ApJ, 183, 1081; Condon et al. 1973, ApJ, 183, 1075; Kuzmin 1965, Radiophysics. [3] Butler & Sault 2003, IAUSS, 1E, 17B. [4] Intema et al. 2014, BASI, 1.

  7. The Ongoing Evolution of a Long-Lived Anticyclone in Saturn’s Great Storm Region as seen by Cassini/VIMS

    NASA Astrophysics Data System (ADS)

    Momary, Thomas W.; Baines, Kevin H.; Badman, Sarah; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.; Sotin, Christophe

    2015-11-01

    Once the home of the enigmatic String of Pearls feature on Saturn, the region of 34o N was the scene of a titanic storm system that swept around the planet in late 2010/2011. It left two things in its wake - a clear 5-μm bright zone around the planet, and a curious and persistent anticylone, both of which remain to this day. We have observed this anticyclone with Cassini/VIMS since 2011 and find that it seems to oscillate up and down latitudinally in this stormy region. Centered at 35.9o planetocentric latitude in May 2011, it drifted northward to 37.8o in 2012, hovered near 37o through 2013, then settled southward back down to ~35.9o in 2014. 2015 has it once again drifting northward to ~37o. It also periodically interacts with the dark band above it exchanging material in August 2013 and May 2015. We measured a prograde zonal drift speed of ~22 m/s in 2012, increasing as much as 60% through 2013, then relaxing back to a more moderate ~15 m/s in 2014 as the oval sagged southward. We expect its current 15.4 m/s rate to increase if it continues to drift northward in latitude, following the Voyager wind profile. The feature has varied in size as well, spanning 4.9o x 3.2o in 2011, elongating zonally to 7.3o x 2.9o by 2013, contracting in 2014 to an average of ~5.5o x ~2.9o, and growing again to ~9o x ~4o in 2015, with an extended tendril of material streaming off one edge in May. By August, it was symmetrically oval again. It has varied in terms of cloudiness, being ~90% 5-μm dark (obscured) in 2011, whereas by 2013 it was mostly bright (clear) with a thin dark edge, now returning to ~90% dark in 2015. By utilizing night observations to isolate thermal flux, we find that the mean 5-μm flux coming from the anticyclone has diminished steadily by about 50% since 2013. The storm latitude of ~34o N itself has remained remarkably 5-μm bright since 2011, but has begun to dim as well, and is now bisected by a thin dark cloudy ribbon which appears associated with the

  8. Dual-Wavelength Terahertz Metasurfaces with Independent Phase and Amplitude Control at Each Wavelength

    NASA Astrophysics Data System (ADS)

    Ding, Jun; Xu, Ningning; Ren, Han; Lin, Yuankun; Zhang, Weili; Zhang, Hualiang

    2016-09-01

    We have designed, fabricated and characterized dual-wavelength metasurfaces that function at two assigned terahertz wavelengths with independent phase and amplitude control at each wavelength. Specifically, we have designed a dual-wavelength achromatic metasurface-based deflector deflecting the incident wave to the same direction at two selected wavelengths, which has circumvented the critical limitation of strong wavelength dependence in the planar metasurface-based devices caused by the resonant nature of the plasmonic structures. As a proof of concept demonstration, the designed dual-wavelength achromatic deflector has been fabricated, and characterized experimentally. The numerical simulations, theoretical predictions, and experimental results agree very well with each other, demonstrating the property of independently manipulating the phase profiles at two wavelengths. Furthermore, another unique feature of the designed metasurface is that it can independently tailor both the phase and amplitude profiles at two wavelengths. This property has been numerically validated by engineering a metasurface-based device to simultaneously generate two diffraction orders at two desired wavelengths.

  9. Dual-Wavelength Terahertz Metasurfaces with Independent Phase and Amplitude Control at Each Wavelength

    PubMed Central

    Ding, Jun; Xu, Ningning; Ren, Han; Lin, Yuankun; Zhang, Weili; Zhang, Hualiang

    2016-01-01

    We have designed, fabricated and characterized dual-wavelength metasurfaces that function at two assigned terahertz wavelengths with independent phase and amplitude control at each wavelength. Specifically, we have designed a dual-wavelength achromatic metasurface-based deflector deflecting the incident wave to the same direction at two selected wavelengths, which has circumvented the critical limitation of strong wavelength dependence in the planar metasurface-based devices caused by the resonant nature of the plasmonic structures. As a proof of concept demonstration, the designed dual-wavelength achromatic deflector has been fabricated, and characterized experimentally. The numerical simulations, theoretical predictions, and experimental results agree very well with each other, demonstrating the property of independently manipulating the phase profiles at two wavelengths. Furthermore, another unique feature of the designed metasurface is that it can independently tailor both the phase and amplitude profiles at two wavelengths. This property has been numerically validated by engineering a metasurface-based device to simultaneously generate two diffraction orders at two desired wavelengths. PMID:27659800

  10. SHORT-WAVELENGTH ELECTROSTATIC FLUCTUATIONS IN THE SOLAR WIND

    SciTech Connect

    Valentini, F.; Perrone, D.; Veltri, P.

    2011-09-20

    Hybrid Vlasov-Maxwell simulations have been used recently to investigate the dynamics of the solar-wind plasma in the tail at short wavelengths of the energy cascade. These simulations have shown that a significant level of electrostatic activity is detected at wavelengths smaller than the proton inertial scale in the longitudinal direction with respect to the ambient magnetic field. In this paper, we describe the results of a new series of hybrid Vlasov-Maxwell simulations that allow us to investigate in more detail the generation process of these electrostatic fluctuations in terms of the electron-to-proton temperature ratio T{sub e} /T{sub p} . This analysis gives evidence for the first time that even in the case of cold electrons, T{sub e} {approx_equal} T{sub p} (the appropriate condition for solar-wind plasmas), the resonant interaction of protons with large-scale left-hand polarized ion-cyclotron waves is responsible for the excitation of short-scale electrostatic fluctuations with an acoustic dispersion relation. Moreover, through our numerical results we propose a physical mechanism to explain the generation of longitudinal proton-beam distributions in typical conditions of the solar-wind environment.

  11. WAVELENGTH CALIBRATION OF THE VLT-UVES SPECTROGRAPH

    SciTech Connect

    Whitmore, Jonathan B.; Griest, Kim; Murphy, Michael T. E-mail: mmurphy@swin.edu.a

    2010-11-01

    We attempt to measure possible miscalibration of the wavelength scale of the VLT-UVES spectrograph. We take spectra of QSO HE0515-4414 through the UVES iodine cell which contains thousands of well-calibrated iodine lines and compare these lines to the wavelength scale from the standard thorium-argon pipeline calibration. Analyzing three exposures of this z = 1.71 QSO, we find two distinct types of calibration shifts needed to correct the Th/Ar wavelength scale. First, there is an overall average velocity shift of between 100 m s{sup -1} and 500 m s{sup -1} depending upon the exposure. Second, within a given exposure, we find intra-order velocity distortions of 100 m s{sup -1} up to more than 200 m s{sup -1}. These calibration errors are similar to, but smaller than, those found earlier in the Keck HIRES spectrometer. We discuss the possible origins of these two types of miscalibration. We also explore the implications of these calibration errors on the systematic error in measurements of {Delta}{alpha}/{alpha}, the change in the fine-structure constant derived from measurement of the relative redshifts of absorption lines in QSO absorption systems. The overall average, exposure-dependent shifts should be less relevant for fine-structure work, but the intra-order shifts have the potential to affect these results. Using either our measured calibration offsets or a Gaussian model with sigma of around 90 m s{sup -1}, Monte Carlo mock experiments find errors in {Delta}{alpha}/{alpha} of between 1 x 10{sup -6} N {sup -1/2}{sub sys} and 3 x 10{sup -6} N {sup -1/2}{sub sys}, where N{sub sys} is the number of systems used and the range is due to dependence on how many metallic absorption lines in each system are compared.

  12. Semiconductor devices for optical communications in 1 micron band of wavelength. [gallium indium arsenide phosphide lasers and diodes

    NASA Technical Reports Server (NTRS)

    Suematsu, Y.; Iga, K.

    1980-01-01

    Crystal growth and the characteristics of semiconductor lasers and diodes for the long wavelength band used in optical communications are examined. It is concluded that to utilize the advantages of this band, it is necessary to have a large scale multiple wavelength communication, along with optical cumulative circuits and optical exchangers.

  13. Multi-Wavelength Observations of Nearby Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Lee, Janice

    2015-08-01

    Do cycles of violent, intense, but short-lived bursts constitute a significant mode of global star formation in present-day galaxies? Such events can have a profound effect on galaxies, particularly those with shallow potential wells, and observational measures of their prevalence inform our understanding of a wide range of issues in galaxy evolution. I will highlight what we have learned about starbursts from multi-wavelength observations of galaxies in the local volume on both galactic and smaller scales, and explore how connections with the study of the deaths of massive stars may further our understanding of open issues in galaxy evolution.

  14. Damping of long-wavelength kinetic alfven fluctuations: linear theory

    SciTech Connect

    Gary, S Peter; Borovsky, Joseph E

    2008-01-01

    The full electromagnetic linear dispersion equation for kinetic Alfven fluctuations in a homogeneous, isotropic, Maxwellian electron-proton plasma is solved numerically in the long wavelength limit. The solutions are summarized by an analytic expression for the damping rate of such modes at propagation sufficiently oblique to the background magnetic field B{sub o} which scales as k{sub {perpendicular}}{sup 2} k{sub {parallel}} where the subscripts denote directions relative to B{sub o}. This damping progressively (although not monotonically) increases with increasing electron {beta}, corresponding to four distinct damping regimes: nonresonant, electron Landau, proton Landau, and proton transit-time damping.

  15. The fabrication of millimeter-wavelength accelerating structures

    SciTech Connect

    Chou, P.J.; Bowden, G.B.; Copeland, M.R.

    1996-11-01

    There is a growing interest in the development of high gradient ({ge} 1 GeV/m) accelerating structures. The need for high gradient acceleration based on current microwave technology requires the structures to be operated in the millimeter wavelength. Fabrication of accelerating structures at millimeter scale with sub-micron tolerances poses great challenges. The accelerating structures impose strict requirements on surface smoothness and finish to suppress field emission and multipactor effects. Various fabrication techniques based on conventional machining and micromachining have been evaluated and tested. These will be discussed and measurement results presented.

  16. Linear response to long wavelength fluctuations using curvature simulations

    NASA Astrophysics Data System (ADS)

    Baldauf, Tobias; Seljak, Uroš; Senatore, Leonardo; Zaldarriaga, Matias

    2016-09-01

    We study the local response to long wavelength fluctuations in cosmological N-body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8–20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

  17. Wavelength selection of fingering instability inside Hele-Shaw cell

    NASA Astrophysics Data System (ADS)

    Kurowski, Pascal; Limat, Laurent; Petitjeans, Philippe; Fernandez, Juan

    2001-11-01

    Fingering instabilities between fluids confined between two plates sometimes involve a typical wavelength λ proportional to the gap h. This unexplained behavior is investigated in the case of the Rayleigh-Taylor instability between two liquids of same viscosity. Using linear stability analysis based on a simplified model of hydrodynamics (Darcy-Stokes equation), we show in particular that, in the miscible case, the wavelength λ of the instability normalized by the gap b of the cell and the dimensionless growth rate Σ remain constant when the Péclet number Pe = fracb^3 Δρ12η D is large ( η viscosity, g gravitational acceleration, D diffusivity, Δρ density difference). The same result holds in the immiscible case for large capillary number C_a=fracb^2Δρ12γ (γ surface tension). In this saturation regime, the dominant wavelength is given by λ=2.3b, while in the opposite limit (low Pe or low C_a) λ scales respectively as fracbPe or fracbC_a^1/2. These theoretical solutions are then compared to experimental measurements for a wide range of Peclet numbers (more than 4 orders of magnitude) : a very good agreement is observed in particular for viscous fluids.

  18. Linear response to long wavelength fluctuations using curvature simulations

    NASA Astrophysics Data System (ADS)

    Baldauf, Tobias; Seljak, Uroš; Senatore, Leonardo; Zaldarriaga, Matias

    2016-09-01

    We study the local response to long wavelength fluctuations in cosmological N-body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8-20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

  19. Differential Expression of ADAM23, CDKN2A (P16), MMP14 and VIM Associated with Giant Cell Tumor of Bone

    PubMed Central

    Conceição, André Luis Giacometti; Babeto, Erica; Candido, Natalia Maria; Franco, Fernanda Craveiro; de Campos Zuccari, Débora Aparecida Pires; Bonilha, Jane Lopes; Cordeiro, José Antônio; Calmon, Marilia Freitas; Rahal, Paula

    2015-01-01

    Though benign, giant cell tumor of bone (GCTB) can become aggressive and can exhibit a high mitotic rate, necrosis and rarely vascular invasion and metastasis. GCTB has unique histologic characteristics, a high rate of multinucleated cells, a variable and unpredictable growth potential and uncertain biological behavior. In this study, we sought to identify genes differentially expressed in GCTB, thus building a molecular profile of this tumor. We performed quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry and analyses of methylation to identify genes that are putatively associated with GCTB. The expression of the ADAM23 and CDKN2A genes was decreased in GCTB samples compared to normal bone tissue, measured by qPCR. Additionally, a high hypermethylation frequency of the promoter regions of ADAM23 and CDKN2A in GCTB was observed. The expression of the MAP2K3, MMP14, TIMP2 and VIM genes was significantly higher in GCTB than in normal bone tissue, a fact that was confirmed by qPCR and immunohistochemistry. The set of genes identified here furthers our understanding of the molecular basis of GCTB. PMID:26078788

  20. Use of Imipenem To Detect KPC, NDM, OXA, IMP, and VIM Carbapenemase Activity from Gram-Negative Rods in 75 Minutes Using Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Kulkarni, M. V.; Zurita, A. N.; Pyka, J. S.; Murray, T. S.; Hodsdon, M. E.

    2014-01-01

    Resistance to extended-spectrum β-lactam antibiotics has led to a greater reliance upon carbapenems, but the expression of carbapenemases threatens to limit the utility of these drugs. Current methods to detect carbapenemase activity are suboptimal, requiring prolonged incubations during which ineffective therapy may be prescribed. We previously described a sensitive and specific assay for the detection of carbapenemase activity using ertapenem and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we assessed 402 Gram-negative rods, including both Enterobacteriaceae and non-Enterobacteriaceae expressing IMP, VIM, KPC, NDM, and/or OXA carbapenemases, by using imipenem, meropenem, and ertapenem with LC-MS/MS assays. LC-MS/MS methods for the detection of intact and hydrolyzed carbapenems from an enrichment broth were developed. No ion suppression was observed, and the limits of detection for all three drugs were below 0.04 μg/ml. The sensitivity and specificity of meropenem and ertapenem for carbapenemase activity among non-Enterobacteriaceae were low, but imipenem demonstrated a sensitivity and specificity of 96% and 95%, respectively, among all Gram-negative rods (GNR) tested, including both Enterobacteriaceae and non-Enterobacteriaceae. LC-MS/MS allows for the analysis of more complex matrices, and this LC-MS/MS assay could easily be adapted for use with primary specimens requiring growth enrichment. PMID:24789180

  1. Protocol for Work place adjusted Intelligent physical exercise reducing Musculoskeletal pain in Shoulder and neck (VIMS): a cluster randomized controlled trial

    PubMed Central

    2010-01-01

    Background Neck and shoulder complaints are common among employees in sedentary occupations characterized by intensive computer use. Specific strength training is a promising type of physical exercise for relieving neck and shoulder pain in office workers. However, the optimal combination of frequency and exercise duration, as well as the importance of exercise supervision, is unknown. The VIMS study investigates in a cluster randomized controlled design the effectiveness of different time wise combinations of specific strength training with identical accumulated volume, and the relevance of training supervision for safe and effective training. Methods/design A cluster randomized controlled trial of 20 weeks duration where employed office workers are randomized to 1 × 60 min, 3 × 20 min, 9 × 7 min per week of specific strength training with training supervision, to 3 × 20 min per week of specific strength training with a minimal amount of training supervision, or to a reference group without training. A questionnaire will be sent to 2000 employees in jobs characterized by intensive computer work. Employees with cardiovascular disease, trauma, hypertension, or serious chronic disease will be excluded. The main outcome measure is pain in the neck and shoulders at week 20. Trial Registration The trial is registered at ClinicalTrials.gov, number NCT01027390. PMID:20687940

  2. A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1986-01-01

    Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

  3. The dynamics of interacting nonlinearities governing long wavelength driftwave turbulence

    SciTech Connect

    Newman, D.E.

    1993-09-01

    Because of the ubiquitous nature of turbulence and the vast array of different systems which have turbulent solutions, the study of turbulence is an area of active research. Much present day understanding of turbulence is rooted in the well established properties of homogeneous Navier-Stokes turbulence, which, due to its relative simplicity, allows for approximate analytic solutions. This work examines a group of turbulent systems with marked differences from Navier-Stokes turbulence, and attempts to quantify some of their properties. This group of systems represents a variety of drift wave fluctuations believed to be of fundamental importance in laboratory fusion devices. From extensive simulation of simple local fluid models of long wavelength drift wave turbulence in tokamaks, a reasonably complete picture of the basic properties of spectral transfer and saturation has emerged. These studies indicate that many conventional notions concerning directions of cascades, locality and isotropy of transfer, frequencies of fluctuations, and stationarity of saturation are not valid for moderate to long wavelengths. In particular, spectral energy transfer at long wavelengths is dominated by the E {times} B nonlinearity, which carries energy to short scale in a manner that is highly nonlocal and anisotropic. In marked contrast to the canonical self-similar cascade dynamics of Kolmogorov, energy is efficiently passed between modes separated by the entire spectrum range in a correlation time. At short wavelengths, transfer is dominated by the polarization drift nonlinearity. While the standard dual cascade applies in this subrange, it is found that finite spectrum size can produce cascades that are reverse directed and are nonconservative in enstrophy and energy similarity ranges. In regions where both nonlinearities are important, cross-coupling between the nolinearities gives rise to large no frequency shifts as well as changes in the spectral dynamics.

  4. Two wavelength satellite laser ranging using SPAD

    NASA Technical Reports Server (NTRS)

    Prochazka, Ivan; Hamal, Karel; Jelinkova, Helena; Kirchner, Georg; Koidl, F.

    1993-01-01

    When ranging to satellites with lasers, there are several principal contributions to the error budget: from the laser ranging system on the ground, from the satellite retroarray geometry, and from the atmosphere. Using a single wavelength, we have routinely achieved a ranging precision of 8 millimeters when ranging to the ERS-1 and Starlette satellites. The systematic error of the atmosphere, assuming the existing dispersion models, is expected to be of the order of 1 cm. Multiple wavelengths ranging might contribute to the refinement of the existing models. Taking into account the energy balance, the existing picosecond lasers and the existing receiver and detection technology, several pairs or multiple wavelengths may be considered. To be able to improve the atmospheric models to the subcentimeter accuracy level, the differential time interval (DTI) has to be determined within a few picoseconds depending on the selected wavelength pair. There exist several projects based on picosecond lasers as transmitters and on two types of detection techniques: one is based on photodetectors, like photomultipliers or photodiodes connected to the time interval meters. Another technique is based on the use of a streak camera as an echo signal detector, temporal analyzer, and time interval vernier. The temporal analysis at a single wavelength using the streak camera showed the complexity of the problem.

  5. Plasmonic All-Optical Tunable Wavelength Shifter

    SciTech Connect

    Flugel, B.; Macararenhas, A.; Snoke, D. W.; Pfeiffer, L. N.; West, K.

    2007-12-01

    At present, wavelength-division-multiplexed fibre lines routinely operate at 10 Gbit s{sup -1} per channel. The transition from static-path networks to true all-optical networks encompassing many nodes, in which channels are added/dropped and efficiently reassigned, will require improved tools for all-optical wavelength shifting. Specifically, one must be able to shift the carrier wavelength (frequency) of an optical data signal over tens of nanometres (a THz range) without the bottleneck of electrical conversion. Popular approaches to this problem make use of the nonlinear interaction between two wavelengths within a semiconductor optical amplifier whereas more novel methods invoke terahertz-frequency electro-optic modulation and polaritons. Here we outline the principles and demonstrate the use of optically excited plasmons as a tunable frequency source that can be mixed with a laser frequency through Raman scattering. The scheme is all-optical and enables dynamical control of the output carrier wavelength simply by varying the power of a control laser.

  6. Cryogenic Amplifier Based Receivers at Submillimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Reck, Theodore and; Schlecht, Erich; Lin, Robert; Deal, William

    2012-01-01

    The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with usable gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown substantial improvement in their noise temperature. This has opened up the real possibility of cryogenic amplifier based heterodyne receivers at submillimeter wavelengths for ground-based, air-borne, and space-based instruments for astrophysics, planetary, and Earth science applications. This paper provides an overview of the science applications at submillimeter wavelengths that will benefit from this technology. It also describes the current state of the InP HEMT based cryogenic amplifier receivers at submillimeter wavelengths.

  7. Integrated nonlinear interferometer with wavelength multicasting functionality.

    PubMed

    Yang, Weili; Yu, Yu; Zhang, Xinliang

    2016-08-01

    Nonlinear interference based on four wave mixing (FWM) is extremely attractive due to its phase sensitivity. On the other hand, wavelength multicasting, which supports data point-to-multipoint connections, is a key functionality to increase the network efficiency and simplify the transmitter and receiver in the wavelength-division multiplexing systems. We propose and experimentally demonstrate a nonlinear interferometer with wavelength multicasting functionality based on single-stage FWM in an integrated silicon waveguide. With a three-pump and dual-signal input, four phase sensitive idlers are obtained at the interferometer output. For a proof-of-concept application, we further theoretically demonstrate the multicasting logic exclusive-OR (XOR) gate for both intensity and phase modulated signals. The proposed scheme would be potentially applied in various on-chip applications for future optical communication system. PMID:27505786

  8. Wavelength agile holmium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Simakov, N.; Daniel, J. M. O.; Ward, J.; Clarkson, W. A.; Hemming, A.; Haub, J.

    2016-03-01

    For the first time, an electronically-controlled, wavelength-agile tuneable holmium-doped fibre laser is presented. A narrow-band acousto-optic tuneable filter was characterized and used as the wavelength selective element to avoid any inertial effects associated with opto-mechanical tuning mechanisms. We demonstrate operation over a 90 nm wavelength range spanning 2040 - 2130 nm. The laser produced >150 mW over this entire range with a signal-to-noise ratio of >45 dB and line-width of ~0.16 nm. Switching times of ~35 μs and sweep rates of up to 9 nm/ms were also demonstrated.

  9. Device for wavelength-selective imaging

    SciTech Connect

    Frangioni, John V.

    2010-09-14

    An imaging device captures both a visible light image and a diagnostic image, the diagnostic image corresponding to emissions from an imaging medium within the object. The visible light image (which may be color or grayscale) and the diagnostic image may be superimposed to display regions of diagnostic significance within a visible light image. A number of imaging media may be used according to an intended application for the imaging device, and an imaging medium may have wavelengths above, below, or within the visible light spectrum. The devices described herein may be advantageously packaged within a single integrated device or other solid state device, and/or employed in an integrated, single-camera medical imaging system, as well as many non-medical imaging systems that would benefit from simultaneous capture of visible-light wavelength images along with images at other wavelengths.

  10. Mechanisms and Methods for Selective Wavelength Filtering

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret (Inventor); Brown, Thomas G. (Inventor); Gruhlke, Russell (Inventor)

    2007-01-01

    An optical filter includes a dielectric waveguide layer, supporting waveguide modes at specific wavelengths and receiving incident light, a corrugated film layer, composed of one of a metal and a semiconductor and positioned adjacent to a second surface of the waveguide layer and a sensor layer, wherein the sensor layer is capable of absorbing optical energy and generating a corresponding electrical signal. The metal film layer supports a plurality of plasmons, the plurality of plasmons producing a first field and is excited by a transverse mode of the waveguide modes at a wavelength interval. The first field penetrates the sensor layer and the sensor layer generates an electrical signal corresponding to an intensity of received incident light within the wavelength interval.

  11. Dynamic polarizabilities and magic wavelengths for dysprosium

    SciTech Connect

    Dzuba, V. A.; Flambaum, V. V.; Lev, Benjamin L.

    2011-03-15

    We theoretically study dynamic scalar polarizabilities of the ground and select long-lived excited states of dysprosium, a highly magnetic atom recently laser cooled and trapped. We demonstrate that there is a set of magic wavelengths of the unpolarized lattice laser field for each pair of states, which includes the ground state and one of these excited states. At these wavelengths, the energy shift due to laser field is the same for both states, which can be useful for resolved sideband cooling on narrow transitions and precision spectroscopy. We present an analytical formula that, near resonances, allows for the determination of approximate values of the magic wavelengths without calculating the dynamic polarizabilities of the excited states.

  12. Variable wavelength selection devices: Physics and applications

    NASA Astrophysics Data System (ADS)

    Xianyu, Haiqing

    Variable wavelength selection (VWS) achieved by implementing tunability to wavelength discriminating devices has generated great interest in basic science, applied physics, and technology. This thesis focuses on the underlying physics and application of several novel wavelength discriminating devices. Holographical polymer dispersed liquid crystals (HPDLCs) are switchable volume gratings formed by exposing a photopolymerizable monomer and liquid crystal mixture to interfering monochromatic light beams. An HPDLCs wavelength discriminating ability along with its switchability, allow it to be utilized in VWS devices. A novel mode HPDLC, total internal reflection (TIR) HPDLC, has been developed as a wavelength selective filter. The grating planes in this device are tilted so that the diffracted light experiences total internal reflection at the glass-air interface and is trapped in the cell until it eventually escapes from an edge. A VWS device is demonstrated by stacking TIR HPDLCs operating at different wavelengths. Converging or diverging recording beams are employed to fabricate chirped reflection HPDLCs with a pitch gradient along the designated direction, creating chirped switchable reflection gratings (CSRGs). A pixelated version of the CSRG is developed herein, and a dynamic spectral equalizer is presented by combining the pixelated CSRG with a prism (for wavelength discrimination). A switchable circular to point converter (SCPC), which enables the random selection of the wavelength bands divided by the Fabry-Perot interferometer utilizing the controllable beam steering capability of transmission HPDLCs, is demonstrated. A random optical cross-switch (TIROL) can be created by integrating a Fabry-Perot interferometer with a stack of SCPC units. The in-plane electric field generated by the interdigitated electrodes is utilized to elongate the helical pitch of a cholesteric liquid crystal and thereby induces a red shift of the transmission reflection peak

  13. Undulators for short wavelength FEL amplifiers

    SciTech Connect

    Schlueter, R.

    1994-08-01

    Issues critical to the design of undulators for use in short wavelength FEL amplifiers, such as attainable on-axis field strength, device compactness, field quality, required magnetic gap, and strong focusing schemes, are discussed. The relative strength of various undulator technologies, including pure permanent magnet, hybrid, warm electromagnetic, pulsed, and superconducting electromagnetic devices in both helical and planar configurations are reviewed. Favored design options for proposed short wavelength FELs, such as the Linac Coherent Light Source at SLAC and the DUV Free-Electron Laser at BNL, are presented.

  14. Effects of Laser Wavelength on Ablator Testing

    NASA Technical Reports Server (NTRS)

    White, Susan M.

    2014-01-01

    Wavelength-dependent or spectral radiation effects are potentially significant for thermal protection materials. NASA atmospheric entry simulations include trajectories with significant levels of shock layer radiation which is concentrated in narrow spectral lines. Tests using two different high powered lasers, the 10.6 micron LHMEL I CO2 laser and the near-infrared 1.07 micron fiber laser, on low density ablative thermal protection materials offer a unique opportunity to evaluate spectral effects. Test results indicated that the laser wavelength can impact the thermal response of an ablative material, in terms of bond-line temperatures, penetration times, mass losses, and char layer thicknesses.

  15. Miniature integrated-optical wavelength analyzer chip

    NASA Astrophysics Data System (ADS)

    Kunz, R. E.; Dübendorfer, J.

    1995-11-01

    A novel integrated-optical chip suitable for realizing compact miniature wavelength analyzers with high linear dispersion is presented. The chip performs the complete task of converting the spectrum of an input beam into a corresponding spatial irradiance distribution without the need for an imaging function. We demonstrate the feasibility of this approach experimentally by monitoring the changes in the mode spectrum of a laser diode on varying its case temperature. Comparing the results with simultaneous measurements by a commercial spectrometer yielded a rms wavelength deviation of 0.01 nm.

  16. Modulation compression for short wavelength harmonic generation

    SciTech Connect

    Qiang, J.

    2010-01-11

    Laser modulator is used to seed free electron lasers. In this paper, we propose a scheme to compress the initial laser modulation in the longitudinal phase space by using two opposite sign bunch compressors and two opposite sign energy chirpers. This scheme could potentially reduce the initial modulation wavelength by a factor of C and increase the energy modulation amplitude by a factor of C, where C is the compression factor of the first bunch compressor. Such a compressed energy modulation can be directly used to generate short wavelength current modulation with a large bunching factor.

  17. An economic Fabry-Perot wavelength reference

    NASA Astrophysics Data System (ADS)

    Fżrész, Gábor; Glenday, Alex; Latham, Christian

    2014-07-01

    Precision radial velocity (PRV) measurements are key in studying exoplanets, and so are wavelength calibrators in PRV instruments. ThAr lamps offer an affordable but somewhat limited solution for the visible passband. Laser frequency combs are ideal calibrators, except the (still) narrow wavelength coverage and large price tag. White light Fabry-Perot (FP) calibrators offer frequency-comb like properties in a more affordable and less complicated package1. Using a commercial solid FP etalon and off-the shelf components we have constructed an economic FP calibrator suitable for observatories on a smaller budget.

  18. Wavelength-Selective Photovoltaics for Power-generating Greenhouses

    NASA Astrophysics Data System (ADS)

    Carter, Sue; Loik, Michael; Shugar, David; Corrado, Carley; Wade, Catherine; Alers, Glenn

    2014-03-01

    While photovoltaic (PV) technologies are being developed that have the potential for meeting the cost target of 0.50/W per module, the cost of installation combined with the competition over land resources could curtail the wide scale deployment needed to generate the Terrawatts per year required to meet the world's electricity demands. To be cost effective, such large scale power generation will almost certainly require PV solar farms to be installed in agricultural and desert areas, thereby competing with food production, crops for biofuels, or the biodiversity of desert ecosystems. This requirement has put the PV community at odds with both the environmental and agricultural groups they would hope to support through the reduction of greenhouse gas emissions. A possible solution to this challenge is the use of wavelength-selective solar collectors, based on luminescent solar concentrators, that transmit wavelengths needed for plant growth while absorbing the remaining portions of the solar spectrum and converting it to power. Costs are reduced through simultaneous use of land for both food and power production, by replacing the PV cells by inexpensive long-lived luminescent materials as the solar absorber, and by integrating the panels directly into existing greenhouse or cold frames. Results on power generation and crop yields for year-long trials done at academic and commercial greenhouse growers in California will be presented.

  19. Wavelength selection of fingering instability inside Hele-Shaw cells

    NASA Astrophysics Data System (ADS)

    Fernandez, J.; Kurowski, P.; Limat, L.; Petitjeans, P.

    2001-11-01

    Fingering instabilities involving fluids confined between two plates sometimes give rise to a typical wavelength λ proportional to the gap h. This unexplained behavior is investigated for the case of the Rayleigh-Taylor instability between two liquids of the same viscosity. Using qualitative scaling arguments and linear stability analysis for a simplified model of hydrodynamics, we show that, in the miscible case, h becomes a natural cut-off when diffusion is negligible, i.e., when the Péclet number Pe=h3Δρg/(ηD) is large (η viscosity, g gravitational acceleration, D diffusivity, Δρ density difference). The same result holds in the immiscible case for large capillary number Ca=h2Δρg/(12γ) (γ surface tension). In this saturation regime, the dominant wavelength is given by λ≈2.3h, while in the opposite limit (low Pe or low Ca) λ scales, respectively, as h/Pe or h/Ca1/2. These results are in agreement with a recent experimental study.

  20. Dual-wavelength erbium-doped fiber laser with tunable wavelength spacing using a twin core fiber-based filter

    NASA Astrophysics Data System (ADS)

    Yin, Guolu; Lou, Shuqin; Wang, Xin; Han, Bolin

    2014-05-01

    A dual-wavelength erbium-doped fiber laser with tunable wavelength spacing was proposed and experimentally demonstrated by using a twin core fiber (TCF)-based filter. Benefiting from the polarization dependence of the TCF-based filter, the laser operated in dual-wavelength oscillation with two orthogonal polarization states. By adjusting the polarization controller, the wavelength spacing was tuned from 0.1 nm to 1.2 nm without shifting the centre position of the two wavelengths. By stretching the TCF, the two wavelengths were simultaneously tuned with fixed wavelength spacing. Such a dual-wavelength fiber laser could find applications in optical fiber sensors and microwave photonics generation.

  1. Discrete wavelength-locked external cavity laser

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S. (Inventor); Silver, Joel A. (Inventor)

    2005-01-01

    An external cavity laser (and method of generating laser light) comprising: a laser light source; means for collimating light output by the laser light source; a diffraction grating receiving collimated light; a cavity feedback mirror reflecting light received from the diffraction grating back to the diffraction grating; and means for reliably tuning the external cavity laser to discrete wavelengths.

  2. Superiority of half-wavelength helicon antennae

    NASA Astrophysics Data System (ADS)

    Porte, L.; Yun, S. M.; Arnush, D.; Chen, F. F.

    2003-05-01

    Plasma densities produced by half- and full-wavelength (HW and FW) helical antennae in helicon discharges are compared. It is found that HW antennae are more efficient than FW ones in producing plasma downstream from the antenna. The measured wave amplitudes and the apparent importance of downstream ionization do not agree with computations.

  3. Wavelength control of visible light laser diodes

    NASA Astrophysics Data System (ADS)

    Goto, N.; Fujii, T.; Nemoto, K.; Suzuki, H.; Nakagawa, K.; Otsu, M.

    1990-04-01

    Wavelength control of visible light laser diodes was studied. By combining an interferometer and a diffraction grating, it became possible to control the wavelength of continuous oscillation in the range of 664 to 673nm, the frequency fine control range being 2GHz. And the spectral linewidth was narrowed to about 44kHz (10 exp minus 7 nm). With the use of a collimator lens, the beam expansion was narrowed to 2mrad. It was confirmed that the pulse output of continuous oscillation visible light laser diodes can be amplified by the YAG laser excitation dye laser. In the case of pulse oscillation, oscillation of 1GHz spectral width was obtained at the wavelength of 0.8 micro m by using an injection synchronization method. In the injection synchronization method, other laser beam is injected in an oscillator and a superior laser beam of synchronized components alone is obtained. As the wavelength control method is now stabilized and satisfies the conditions of narrow band, it has the prospect to be applied to the laser uranium enrichment technology.

  4. Resolving the Moth at Millimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    Ricarte, Angelo; Moldvai, Noel; Hughes, A. Meredith; Duchêne, Gaspard; Williams, Jonathan P.; Andrews, Sean M.; Wilner, David J.

    2013-09-01

    HD 61005, also known as "The Moth," is one of only a handful of debris disks that exhibit swept-back "wings" thought to be caused by interaction with the ambient interstellar medium (ISM). We present 1.3 mm Submillimeter Array observations of the debris disk around HD 61005 at a spatial resolution of 1.''9 that resolve the emission from large grains for the first time. The disk exhibits a double-peaked morphology at millimeter wavelengths, consistent with an optically thin ring viewed close to edge-on. To investigate the disk structure and the properties of the dust grains we simultaneously model the spatially resolved 1.3 mm visibilities and the unresolved spectral energy distribution (SED). The temperatures indicated by the SED are consistent with expected temperatures for grains close to the blowout size located at radii commensurate with the millimeter and scattered light data. We also perform a visibility-domain analysis of the spatial distribution of millimeter-wavelength flux, incorporating constraints on the disk geometry from scattered light imaging, and find suggestive evidence of wavelength-dependent structure. The millimeter-wavelength emission apparently originates predominantly from the thin ring component rather than tracing the "wings" observed in scattered light. The implied segregation of large dust grains in the ring is consistent with an ISM-driven origin for the scattered light wings.

  5. RESOLVING THE MOTH AT MILLIMETER WAVELENGTHS

    SciTech Connect

    Ricarte, Angelo; Moldvai, Noel; Hughes, A. Meredith; Duchene, Gaspard; Williams, Jonathan P.; Andrews, Sean M.; Wilner, David J.

    2013-09-01

    HD 61005, also known as ''The Moth'', is one of only a handful of debris disks that exhibit swept-back ''wings'' thought to be caused by interaction with the ambient interstellar medium (ISM). We present 1.3 mm Submillimeter Array observations of the debris disk around HD 61005 at a spatial resolution of 1.''9 that resolve the emission from large grains for the first time. The disk exhibits a double-peaked morphology at millimeter wavelengths, consistent with an optically thin ring viewed close to edge-on. To investigate the disk structure and the properties of the dust grains we simultaneously model the spatially resolved 1.3 mm visibilities and the unresolved spectral energy distribution (SED). The temperatures indicated by the SED are consistent with expected temperatures for grains close to the blowout size located at radii commensurate with the millimeter and scattered light data. We also perform a visibility-domain analysis of the spatial distribution of millimeter-wavelength flux, incorporating constraints on the disk geometry from scattered light imaging, and find suggestive evidence of wavelength-dependent structure. The millimeter-wavelength emission apparently originates predominantly from the thin ring component rather than tracing the ''wings'' observed in scattered light. The implied segregation of large dust grains in the ring is consistent with an ISM-driven origin for the scattered light wings.

  6. SDIO long wavelength infrared detector requirements

    NASA Technical Reports Server (NTRS)

    Duston, Dwight

    1990-01-01

    The Strategic Defense Initiative Organization (SDIO) has a significant requirement for infrared sensors for surveillance, tracking and discrimination of objects in space. Projected SDIO needs cover the range from short wavelengths out to 30 microns. Large arrays are required, and producibility and cost are major factors. The SDIO is pursuing several approaches including innovative concepts based on semiconductors and superconductors.

  7. The wavelength dependence of Triton's light curve

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Veverka, J.; Helfenstein, P.; Mcewen, A.

    1991-01-01

    Using Voyager observations, it is demonstrated that Triton's orbital light curve is strongly wavelength-dependent, a characteristic which readily explains some of the apparent discrepancies among pre-Voyager telescopic measurements. Specifically, a light curve amplitude (peak to peak) is found that decreases systematically with increasing wavelength from about 0.08 magnitude (peak to peak) near 200 nm to less than 0.02 magnitude near 1000 nm. Peak brightness occurs near 90 deg orbital longitude (leading hemisphere). The brightness variation across this hemisphere is close to sinusoidal; the variation across the darker hemisphere is more complex. The decrease in light curve amplitude with increasing wavelength appears to be due to a decrease in contrast among surface markings, rather than to atmospheric obscuration. The model also explains the observed decrease in the amplitude of Triton's light curve at visible wavelengths over the past decade, a decrease related to the current migration of the subsolar latitude toward the south pole; it is predicted that this trend will continue into the 1990s.

  8. Two-wavelength spatial-heterodyne holography

    DOEpatents

    Hanson, Gregory R.; Bingham, Philip R.; Simpson, John T.; Karnowski, Thomas P.; Voelkl, Edgar

    2007-12-25

    Systems and methods are described for obtaining two-wavelength differential-phase holograms. A method includes determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.

  9. Devices for wavelength switching in optical networks

    SciTech Connect

    d`Alessandro, A.; Baran, J.E.; Smith, D.A.

    1994-12-31

    Wavelength routing crossconnects are considered the core of WDM optical networks. They consist of optical switches independently rearrangeable for each wavelength channel and for any input-output configuration so that any path can be chosen almost arbitrarily by the network users. In general the implementation of the wavelength routing function requires complex switch arrays. Very simple wavelength-selection crossconnects can be realized by using acousto-optic switches (AOS), because of their unique ability of processing several optical signals simultaneously and their low driving power consumption, less than 10 mW/channel. AOS`s can be considered a particular evolution of acousto-optical tunable filters, whose integrated optic version on lithium niobate has been developed in several research institutions around the world in the past decade. This paper reviews the last accomplishments of AOS`s, whose specifications are directly tied with optical network requirements, the foremost challenge being a strong suppression of crosstalk. Dilated AOS`s can reduce interport crosstalk to below {minus}30 dB and apodization of acousto-optic interaction can reduce interchannel crosstalk to below {minus}15 dB during multiwavelength operation.

  10. Electricity and short wavelength radiation generator

    DOEpatents

    George, E.V.

    1985-08-26

    Methods and associated apparati for use of collisions of high energy atoms and ions of He, Ne, or Ar with themselves or with high energy neutrons to produce short wavelength radiation (lambda approx. = 840-1300 A) that may be utilized to produce cathode-anode currents or photovoltaic currents.

  11. Self Calibration of a 2-wavelength Pyrometer

    NASA Technical Reports Server (NTRS)

    Ng, Daniel

    1998-01-01

    Pyrometers require calibrations to determine their instrument constants before they can be used in remote temperature measurements. These constants reflect the combined effects of detector response, the transmissivities of intervening optical media (windows and gases) and the emissivity of the measured surface. We describe here the principal and the demonstration of self calibrating 2-wavelength pyrometer.

  12. SWCam: the short wavelength camera for the CCAT Observatory

    NASA Astrophysics Data System (ADS)

    Stacey, Gordon J.; Parshley, Stephen; Nikola, Thomas; Cortes-Medellin, German; Schoenwald, Justin; Rajagopalan, Ganesh; Niemack, Michael D.; Jenness, Tim; Gallardo, Patricio; Koopman, Brian; Dowell, Charles D.; Day, Peter K.; Hollister, Matthew I.; Kovacs, Attila; LeDuc, Henry G.; McKenney, Christopher M.; Monroe, Ryan M.; Yoshida, Hiroshige; Zmuidzinas, Jonas; Swenson, Loren J.; Radford, Simon J.; Nguyen, Hien Trong; Mroczkowski, Anthony K.; Glenn, Jason; Wheeler, Jordan; Maloney, Philip; Brugger, Spencer; Adams, Joseph D.; Bertoldi, Frank; Schaaf, Reinhold; Halpern, Mark; Scott, Douglas; Marsden, Galen; Sayers, Jack; Chapman, Scott; Vieira, Joaquin D.

    2014-08-01

    We describe the Short Wavelength Camera (SWCam) for the CCAT observatory including the primary science drivers, the coupling of the science drivers to the instrument requirements, the resulting implementation of the design, and its performance expectations at first light. CCAT is a 25 m submillimeter telescope planned to operate at 5600 meters, near the summit of Cerro Chajnantor in the Atacama Desert in northern Chile. CCAT is designed to give a total wave front error of 12.5 μm rms, so that combined with its high and exceptionally dry site, the facility will provide unsurpassed point source sensitivity deep into the short submillimeter bands to wavelengths as short as the 200 μm telluric window. The SWCam system consists of 7 sub-cameras that address 4 different telluric windows: 4 subcameras at 350 μm, 1 at 450 μm, 1 at 850 μm, and 1 at 2 mm wavelength. Each sub-camera has a 6' diameter field of view, so that the total instantaneous field of view for SWCam is equivalent to a 16' diameter circle. Each focal plane is populated with near unit filling factor arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) with pixels scaled to subtend an solid angle of (λ/D)2 on the sky. The total pixel count is 57,160. We expect background limited performance at each wavelength, and to be able to map < 35(°)2 of sky to 5 σ on the confusion noise at each wavelength per year with this first light instrument. Our primary science goal is to resolve the Cosmic Far-IR Background (CIRB) in our four colors so that we may explore the star and galaxy formation history of the Universe extending to within 500 million years of the Big Bang. CCAT's large and high-accuracy aperture, its fast slewing speed, use of instruments with large format arrays, and being located at a superb site enables mapping speeds of up to three orders of magnitude larger than contemporary or near future facilities and makes it uniquely sensitive, especially in the short submm bands.

  13. Using Long Wavelength Gravity to Understand Continental Structure and Processes

    NASA Astrophysics Data System (ADS)

    Webb, Susan

    2013-04-01

    In most interpretations of gravity data, the long wavelength signal is removed as an unimportant regional contribution. This convention is largely historical; in the past it was difficult to model data at a variety of scales, and regional/residual separation became standard practice. This is especially true in exploration studies where near surface ore deposits are the target (e.g. LaFehr and Nabighian, 2012). With the development of a large variety of rapid 2D and 3D gravity modelling packages that are widely available, a more regional context for ore deposits and other crustal features can be considered. The inclusion of the regional long wavelength signal in the interpretation can dramatically alter the result, especially when the scale of consideration is on the order of the scale of crustal flexure. Large basins, such as the South African Karoo basin (Mesozoic) and even the smaller Witwatersrand basin (Archean), are likely to have deformed the Moho during their formation, although not all of these features appear to be preserved in present-day Moho geometry. Gravity modelling to Moho depths may dramatically alter the detailed interpretation of the deeper sections of these basins, with implications for resources such as gold, coal, gas and even carbon capture and storage (CCS). A clear cut example of this is seen in the interpretation of the gravity data of the Bushveld Complex (BC). When the crust is allowed to flex, the mafic lithologies of the BC can be allowed to connect laterally, resulting in an enormous layered intrusion 400 x 400 km across. This interpretation has been confirmed by the presence of BC xenoliths in a kimberlite near the centre of the Complex (Webb, Ashwal and Cawthorn, 2011, Contrib. Mineral. Petrol., 162: 101-107). The implication is that the BC mineral resources are also likely to be laterally connected, easily quadrupling the amount of mineralization, although the depth of the deposits remains uncertain. Due to the inherent ambiguity

  14. Driving-laser wavelength dependence of high-order harmonic generation in H{sub 2}{sup +} molecules

    SciTech Connect

    Liu Candong; Zeng Zhinan; Wei Pengfei; Liu Peng; Li Ruxin; Xu Zhizhan

    2010-03-15

    The electron-nuclear dynamics of one-dimensional H{sub 2}{sup +} molecular high harmonic generation is investigated by numerical integration of the non-Born-Oppenheimer time-dependent Schroedinger equation. It is found that the nuclear motion and electron ionization are more significant for the longer wavelength and the stronger intensity of the driving laser pulse. When the ground-state H{sub 2}{sup +} molecule is driven by a short laser pulse (ten optical cycles in the calculations), a strong signature of nuclear motion is seen in the wavelength scaling (800-2000 nm) of harmonic yield, following a {lambda}{sup -(7-8)} scaling law at a constant laser intensity. It is attributed to the fast ground-state depletion induced by the strong nuclear motion, when using the long wavelength. Consequently, the wavelength scaling gives an insight into the nuclear dynamics.

  15. Choice of the proper wavelength for photochemotherapy

    NASA Astrophysics Data System (ADS)

    Moan, Johan; Iani, Vladimir; Ma, LiWei

    1996-01-01

    All photosensitizers applied in experimental- and clinical-photochemotherapy (PCT) have broad absorption spectra stretching from the ultraviolet up to 6 - 700 nm. Light of wavelengths in the red part of the spectrum is chosen for PCT even though the extinction coefficients of the sensitizers are usually smaller in this wavelength region than at shorter wavelengths. Thus, if one wants to treat superficial tumors or skin disorders, this may be a wrong choice. Two pieces of information are needed in order to make a proper choice of wavelength to treat a lesion of a given depth: the wavelength dependence of the optical penetration depth into tissue, and the action spectrum for tumor destruction. Additionally, the skin photosensitivity induced by the drug should be considered. We have non-invasively measured the optical penetration spectra of human tissues in vivo and the fluorescence excitation spectra for several sensitizers, including protoporphyrin (PpIX), in cells. Assuming that the action spectrum for cell inactivation can be approximated by the fluorescence excitation spectrum of the sensitizer -- which is indeed the case for a number of sensitizers in cells in vitro -- we have considered the situation for 5-aminolevulinic acid-induced PpIX in human tissue. All the way down to about 2 mm below the surface light in the Soret band (-410 nm) would give the largest cell inactivation, while at depth exceeding 2 mm, the conventional 635 nm light would be optimal. Light at the argon laser wavelength 514.5 nm is more efficient than light at 635 nm down to 1 mm. From the surface and down to 6 mm, the 635 nm peak of the excitation spectrum of PpIX, as evaluated per photon incident on the skin surface, is redshifted by less than 2 nm. In some cases photosensitizing photoproducts are formed during PCT, such as photoprotoporphyrin during PCT with PpIX. In such cases it may be advantageous to apply a broad-band light source with a spectrum that covers also part of the action

  16. Efficacy of humanized high-dose meropenem, cefepime, and levofloxacin against Enterobacteriaceae isolates producing Verona integron-encoded metallo-β-lactamase (VIM) in a murine thigh infection model.

    PubMed

    Ghazi, Islam M; Crandon, Jared L; Lesho, Emil P; McGann, Patrick; Nicolau, David P

    2015-11-01

    We aimed to describe the in vivo activity of humanized pharmacokinetic exposures of meropenem and comparators against Verona integron-encoded metallo-β-lactamase (MBL) (VIM)-producing Enterobacteriaceae in a murine model. Levofloxacin activity was predicted by its MIC, and cefepime activity displayed variability, whereas meropenem produced a >1 log CFU reduction against all isolates despite high MICs indicative of resistance. Our results suggest that despite in vitro resistance, high-dose meropenem may be a possible option against infections caused by Enterobacteriaceae producing MBL-type carbapenemases. PMID:26416855

  17. Multi-Wavelength Observations of Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Williams, B.

    2012-01-01

    Supernova remnants (SNRs) provide a laboratory for studying various astrophysical processes, including particle acceleration, thermal and non thermal emission processes across the spectrum, distribution of heavy elements, the physics of strong shock waves, and the progenitor systems and environments of supernovae. Long studied in radio and X-rays, the past decade has seen a dramatic increase in the detection and subsequent study of SNRs in the infrared and gamma-ray regimes. Understanding the evolution of SNRs and their interaction with the interstellar medium requires a multi-wavelength approach. I will review the various physical processes observed in SNRs and how these processes are intertwined. In particular, I will focus on X-ray and infrared observations, which probe two very different but intrinsically connected phases of the ISM: gas and dust. I will discuss results from multi-wavelength studies of several SNRs at various stages of evolution, including Kepler, RCW 86, and the Cygnus Loop.

  18. WAVELENGTH CALIBRATION OF THE HAMILTON ECHELLE SPECTROGRAPH

    SciTech Connect

    Pakhomov, Yu. V.; Zhao, G.

    2013-10-01

    We present the wavelength calibration of the Hamilton Echelle Spectrograph at Lick Observatory. The main problem with the calibration of this spectrograph arises from the fact that thorium lines are absent in the spectrum of the presumed ThAr hollow-cathode lamp now under operation; numerous unknown strong lines, which have been identified as titanium lines, are present in the spectrum. We estimate the temperature of the lamp's gas which permits us to calculate the intensities of the lines and to select a large number of relevant Ti I and Ti II lines. The resulting titanium line list for the Lick hollow-cathode lamp is presented. The wavelength calibration using this line list was made with an accuracy of about 0.006 Å.

  19. Dual-wavelength laser with topological charge

    NASA Astrophysics Data System (ADS)

    Yu, Haohai; Xu, Miaomiao; Zhao, Yongguang; Wang, Yicheng; Han, Shuo; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

    2013-09-01

    We demonstrate the simultaneous oscillation of different photons with equal orbital angular momentum in solid-state lasers for the first time to our knowledge. Single tunable Hermite-Gaussian (HG0,n) (0 ≤ n ≤ 7) laser modes with dual wavelength were generated using an isotropic cavity. With a mode-converter, the corresponding Laguerre-Gaussian (LG0,n) laser modes were obtained. The oscillating laser modes have two types of photons at the wavelengths of 1077 and 1081 nm and equal orbital angular momentum of nħ per photon. These results identify the possibility of simultaneous oscillation of different photons with equal and controllable orbital angular momentum. It can be proposed that this laser should have promising applications in many fields based on its compact structure, tunable orbital angular momentum, and simultaneous oscillation of different photons with equal orbital angular momentum.

  20. The Long Wavelength Array Software Library

    NASA Astrophysics Data System (ADS)

    Dowell, Jayce; Wood, Daniel; Stovall, Kevin; Ray, Paul S.; Clarke, Tracy; Taylor, Gregory

    2012-12-01

    The Long Wavelength Array Software Library (LSL) is a Python module that provides a collection of utilities to analyze and export data collected at the first station of the Long Wavelength Array, LWA1. Due to the nature of the data format and large-N (≳100 inputs) challenges faced by the LWA, currently available software packages are not suited to process the data. Using tools provided by LSL, observers can read in the raw LWA1 data, synthesize a filter bank, and apply incoherent de-dispersion to the data. The extensible nature of LSL also makes it an ideal tool for building data analysis pipelines and applying the methods to other low frequency arrays.

  1. Aperture-synthesis interferometry at optical wavelengths

    NASA Technical Reports Server (NTRS)

    Burke, Bernard F.

    1987-01-01

    The prospects for applying aperture-synthesis interferometry to the optical domain are reviewed. The radio examples such as the VLA provide a model, since the concepts are equally valid for radio and optical wavelengths. If scientific problems at the milliarc-second resolution level (or better) are to be addressed, a space-based optical array seems to be the only practical alternative, for the same reasons that dictated array development at radio wavelengths. One concept is examined, and speculations are offered concerning the prospects for developing real systems. Phase-coherence is strongly desired for a practical array, although self-calibration and phase-closure techniques allow one to relax the restriction on absolute phase stability. The design of an array must be guided by the scientific problems to be addressed.

  2. Coordinated observations of PHEMU at radio wavelengths.

    NASA Astrophysics Data System (ADS)

    Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.; Kraus, A.; Mack, K.-H.

    We present preliminary results for our study of mutual phenomena of the Galilean satellites performed at radio wavelengths with the Medicina and Noto antennas of the Istituto di Radioastronomia \\textendash{} INAF, and with the Effelsberg 100-m radio telescope of the Max-Planck-Institute for Radioastronomy. Measurements of the radio flux density variation occurred during the mutual occultations of Io by Europa and Ganymede were carried out during the PHEMU09 campaign at K- and Q-band. Flux density variations observed for the first time at radio wavelengths are consistent with the typical optical patterns measured when partial occultations occurred. The flux density drops indicate a non-linear dependence with the percentage of overlapped area.

  3. Short wavelength striations on expanding plasma clouds

    SciTech Connect

    Winske, D.; Gary, S.P.

    1989-01-01

    The growth and evolution of short wavelength (

  4. Deformable mirror for short wavelength applications

    DOEpatents

    Chapman, Henry N.; Sweeney, Donald W.

    1999-01-01

    A deformable mirror compatible with short wavelength (extreme ultraviolet) radiation that can be precisely controlled to nanometer and subnanometer accuracy is described. Actuators are coupled between a reaction plate and a face plate which has a reflective coating. A control system adjusts the voltage supplied to the actuators; by coordinating the voltages supplied to the actuators, the reflective surface of the mirror can be deformed to correct for dimensional errors in the mirror or to produce a desired contour.

  5. Tuning the Activation Wavelength of Photochromic Oxazines.

    PubMed

    Swaminathan, Subramani; Garcia-Amorós, Jaume; Thapaliya, Ek Raj; Nonell, Santi; Captain, Burjor; Raymo, Françisco M

    2016-06-17

    The activation wavelength of a photochromic oxazine can be shifted bathochromically with the introduction of a methoxy substituent on the chromophore responsible for initiating the photochemical transformation. This structural modification permits switching under mild illumination conditions, enhances the photoisomerization quantum yield and ensures outstanding fatigue resistance. Thus, these results can guide the design of new members of this family of photoresponsive molecular switches with improved photochemical and photophysical properties. PMID:27003328

  6. High-speed wavelength-swept lasers

    NASA Astrophysics Data System (ADS)

    Hsu, Kevin

    2006-05-01

    High-speed wavelength-swept lasers capable of providing wide frequency chirp and flexible temporal waveforms could enable numerous advanced functionalities for defense and security applications. Powered by high spectral intensity at rapid sweep rates across a wide wavelength range in each of the 1060nm, 1300nm, and 1550nm spectral windows, these swept-laser systems have demonstrated real-time monitoring and superior signal-to-noise ratio measurements in optical frequency domain imaging, fiber-optic sensor arrays, and near-IR spectroscopy. These same capabilities show promising potentials in laser radar and remote sensing applications. The core of the high-speed swept laser incorporates a semiconductor gain module and a high-performance fiber Fabry- Perot tunable filter (FFP-TF) to provide rapid wavelength scanning operations. This unique design embodies the collective advantages of the semiconductor amplifier's broad gain-bandwidth with direct modulation capability, and the FFP-TF's wide tuning ranges (>200nm), high finesse (1000 to 10,000), low-loss (<3dB), and fast scan rates reaching 20KHz. As a result, the laser can sweep beyond 100nm in 25μsec, output a scanning peak power near mW level, and exhibit excellent peak signal-to-spontaneous-emission ratio >80dB in static mode. When configured as a seed laser followed by post amplification, the swept spectrum and power can be optimized for Doppler ranging and remote sensing applications. Furthermore, when combined with a dispersive element, the wavelength sweep can be converted into high-speed and wide-angle spatial scanning without moving parts.

  7. Tuning the Activation Wavelength of Photochromic Oxazines.

    PubMed

    Swaminathan, Subramani; Garcia-Amorós, Jaume; Thapaliya, Ek Raj; Nonell, Santi; Captain, Burjor; Raymo, Françisco M

    2016-06-17

    The activation wavelength of a photochromic oxazine can be shifted bathochromically with the introduction of a methoxy substituent on the chromophore responsible for initiating the photochemical transformation. This structural modification permits switching under mild illumination conditions, enhances the photoisomerization quantum yield and ensures outstanding fatigue resistance. Thus, these results can guide the design of new members of this family of photoresponsive molecular switches with improved photochemical and photophysical properties.

  8. Source of coherent short wavelength radiation

    DOEpatents

    Villa, Francesco

    1990-01-01

    An apparatus for producing coherent radiation ranging from X-rays to the far ultraviolet (i.e., 1 Kev to 10 eV) utilizing the Compton scattering effect. A photon beam from a laser is scattered on a high energy electron bunch from a pulse power linac. The short wavelength radiation produced by such scattering has sufficient intensity and spatial coherence for use in high resolution applications such as microscopy.

  9. Varactor diodes for millimeter and submillimeter wavelengths

    NASA Technical Reports Server (NTRS)

    Rizzi, Brian J.; Hesler, Jeffrey L.; Dossal, Hasan; Crowe, Thomas W.

    1992-01-01

    Whisker-contacted GaAs Schottky barrier varactor diodes are the most common high-frequency multiplier element in use today. They are inherently simple devices that have very high frequency response and have been used to supply local oscillator power for Schottky heterodyne receivers to frequencies approaching 700 GHz. This paper discusses the development of improved varactor diode technology for space based applications at millimeter and submillimeter wavelengths.

  10. Two-wavelength lidar inversion algorithm.

    PubMed

    Kunz, G J

    1999-02-20

    Potter [Appl. Opt. 26, 1250 (1987)] has presented a method to determine profiles of the atmospheric aerosol extinction coefficients by use of a two-wavelength lidar with the assumptions of a constant value for the extinction-to-backscatter ratio for each wavelength and a constant value for the ratio between the two extinction coefficients at the two wavelengths. Triggered by this idea, Ackermann [Appl. Opt. 36, 5134 (1997)] expanded this method to consider lidar returns that are a composition of scattering by atmospheric aerosols and molecules, assuming that the molecular scattering is known. In both papers the method is based on the well-known solutions of Bernoulli's differential equation in an iterative scheme with an unknown boundary transmission condition. This boundary condition is less sensitive to noise than boundary extinction conditions. My main purpose is to critically consider the principle behind Potter's method, because it seems that there are several reasons why the number of solutions is not limited to one, as suggested by his original work.

  11. Wavelength switching in an optical klystron

    SciTech Connect

    Berryman, K.W.; Smith, T.I.

    1995-12-31

    A symmetric optical klystron consists of two identical undulator sections separated a dispersive section. For a device of a given length, an optical klystron is capable of producing much more bunching, and therefore more gain, than a traditional undulator. Another consequence of introducing dispersion between two undulator sections is that the overall spontaneous radiation pattern results from the interference between the two undulator sections, and as such resembles a standard undulator radiation pattern modulated by a sinusoidal interference term. The presence of several wavelength peaks in the spontaneous lineshape implies an equal number of peaks in the gain spectrum. If the strength of the dispersion section is adjusted to provide nearly equal gain on the two largest of these peaks, then they will compete, and the FEL may switch wavelengths based on noise, cavity length, or other perturbations. We provide the first observations of this behavior, using the FIREFLY system at the Stanford Picosecond FEL Center. In FIREFLY, relative wavelength switching by more than 3%--more than twice the laser linewidth-has been observed by varying dispersion section strength, while at intermediate points stable switching has also been observed as a function of cavity length.

  12. Multiple wavelength X-ray monochromators

    DOEpatents

    Steinmeyer, Peter A.

    1992-11-17

    An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focussing the separate first and second output x-ray radiation wavelengths into separate focal points.

  13. Multiple wavelength X-ray monochromators

    DOEpatents

    Steinmeyer, P.A.

    1992-11-17

    An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focusing the separate first and second output x-ray radiation wavelengths into separate focal points. 3 figs.

  14. Long Wavelength Ripples in the Nearshore

    NASA Astrophysics Data System (ADS)

    Alcinov, T.; Hay, A. E.

    2008-12-01

    Sediment bedforms are ubiquitous in the nearshore environment, and their characteristics and evolution have a direct effect on the hydrodynamics and the rate of sediment transport. The focus of this study is long wavelength ripples (LWR) observed at two locations in the nearshore at roughly 3m water depth under combined current and wave conditions in Duck, North Carolina. LWR are straight-crested bedforms with wavelengths in the range of 20-200cm, and steepness of about 0.1. They occur in the build up and decay of storms, in a broader range of values of the flow parameters compared to other ripple types. The main goal of the study is to test the maximum gross bedform-normal transport (mGBNT) hypothesis, which states that the orientation of ripples in directionally varying flows is such that the gross sediment transport normal to the ripple crest is maximized. Ripple wavelengths and orientation are measured from rotary fanbeam images and current and wave conditions are obtained from electromagnetic (EM) flowmeters and an offshore pressure gauge array. Preliminary tests in which transport direction is estimated from the combined flow velocity vectors indicate that the mGBNT is not a good predictor of LWR orientation. Results from tests of the mGBNT hypothesis using a sediment transport model will be presented.

  15. Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems.

    PubMed

    Zhu, Hai-Feng; Zele, Andrew J; Suheimat, Marwan; Lambert, Andrew J; Atchison, David A

    2016-08-01

    This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes.

  16. Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems.

    PubMed

    Zhu, Hai-Feng; Zele, Andrew J; Suheimat, Marwan; Lambert, Andrew J; Atchison, David A

    2016-08-01

    This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes. PMID:27580041

  17. Alternative explanation for intermediate--wavelength magnetic anomalies

    SciTech Connect

    Shure, L.; Parker, R.L.

    1981-12-10

    Harrison and Carle and others have examined very long profiles of the magnetic field and have calculated one-dimensional power spectra. In these they expect to see, but do not find, a minimum in power at intermediate wavelengths, between 65 and 150 km. Conventional one-dimensional models of the field predict very little power in this band, which lies between the spectral peaks arising from sources in the crust and the core. Mantle sources or high-intensity, long-wavelength magnetizations have been proposed to account for the observations. An alternative, more plausible explanation is that one-dimensional spectra of two-dimensional fields contain contributions from wavenumbers in the perpendicular (i.e., nonsampled) direction. Unless the seafloor spreading anomalies are perfectly lineated at right angles to the profile, some low-wavenumber energy must be attributed to this effect; we propose that such directional aliasing is a major factor in the power spectra. To support this idea we discuss theoretical models and analyze a large-scale marine survey.

  18. Probing the Multi-Wavelength Nature of Stellar Flares

    NASA Astrophysics Data System (ADS)

    Osten, R. A.; Brown, A.; Ayres, T. R.; Linsky, J. L.

    2000-05-01

    The Extreme Ultraviolet Explorer has been instrumental in advancing our understanding of flares on late-type stars. Its long observations of coronal sources for > 100 ks are perfectly matched for studying flaring variability on active binary systems, whose flaring time scales can last for tens of hours. This ability makes EUVE an ideal companion for multi-wavelength observations of flares, as it can place the shorter observations of other satellites and telescopes in perspective of the coronal variability. For example, EUVE recently participated in a campaign to observe the RS CVn binary HR 1099 (V711 Tau) during a calibration observation with the Chandra X-ray Observatory, with accompanying high-resolution UV coverage from HST/STIS and radio coverage from the VLA. I will discuss the results of this campaign as well as earlier multi-wavelength observations involving EUVE and other satellites such as ASCA, RXTE, and BeppoSAX of flaring variability on active binary systems. RAO acknowledges funding from a NASA GSRP fellowship, grant number NGT5-50241. AB and TRA acknowledge funding from NASA grant NAG5-3226 and JLL acknowledges support from NASA through grants S-56500-D and H-04630D.

  19. A Novel Portable Multi-Wavelength Laser System

    NASA Astrophysics Data System (ADS)

    Charlton, Andy; Dickinson, B.

    There is an established need for a portable and affordable Q-switched laser system for use in studio conservation and small scale field use. The ideal system would be capable of producing a variety of wavelengths ranging from the ultraviolet to the infrared with sufficient energy per pulse to treat a wide range of materials including stone, marble, terracotta, wood, organic materials, bone, parchment, textiles, and metals. In this paper we report on such a system which is capable of delivering Q-switched output at 1,064nm in excess of 300mJ per pulse and at repetition rates of up to 25 Hz. Additional outputs are also reported at 266 nm, 355 nm, 532 nm, and 2.94 μm. Preliminary cleaning results on a small range of objects using the Q-switched 1,064nm output are presented.

  20. Acoustic dynamics of network-forming glasses at mesoscopic wavelengths.

    PubMed

    Ferrante, C; Pontecorvo, E; Cerullo, G; Chiasera, A; Ruocco, G; Schirmacher, W; Scopigno, T

    2013-01-01

    The lack of long-range structural order in amorphous solids induces well known thermodynamic anomalies, which are the manifestation of distinct peculiarities in the vibrational spectrum. Although the impact of such anomalies vanishes in the long wavelength, elastic continuum limit, it dominates at length scales comparable to interatomic distances, implying an intermediate transition regime still poorly understood. Here we report a study of such mesoscopic domains by means of a broadband version of picosecond photo-acoustics, developed to coherently generate and detect hypersonic sound waves in the sub-THz region with unprecedented sampling efficiency. We identify a temperature-dependent fractal v(3/2) frequency behaviour of the sound attenuation, pointing to the presence of marginally stable regions and a transition between the two above mentioned limits. The essential features of this behaviour are captured by a theoretical approach based on random spatial variation of the shear modulus, including anharmonic interactions.

  1. Acoustic dynamics of network-forming glasses at mesoscopic wavelengths

    PubMed Central

    Ferrante, C.; Pontecorvo, E.; Cerullo, G.; Chiasera, A.; Ruocco, G.; Schirmacher, W.; Scopigno, T.

    2013-01-01

    The lack of long-range structural order in amorphous solids induces well known thermodynamic anomalies, which are the manifestation of distinct peculiarities in the vibrational spectrum. Although the impact of such anomalies vanishes in the long wavelength, elastic continuum limit, it dominates at length scales comparable to interatomic distances, implying an intermediate transition regime still poorly understood. Here we report a study of such mesoscopic domains by means of a broadband version of picosecond photo-acoustics, developed to coherently generate and detect hypersonic sound waves in the sub-THz region with unprecedented sampling efficiency. We identify a temperature-dependent fractal v3/2 frequency behaviour of the sound attenuation, pointing to the presence of marginally stable regions and a transition between the two above mentioned limits. The essential features of this behaviour are captured by a theoretical approach based on random spatial variation of the shear modulus, including anharmonic interactions. PMID:23653205

  2. Wavelength meter having single mode fiber optics multiplexed inputs

    DOEpatents

    Hackel, R.P.; Paris, R.D.; Feldman, M.

    1993-02-23

    A wavelength meter having a single mode fiber optics input is disclosed. The single mode fiber enables a plurality of laser beams to be multiplexed to form a multiplexed input to the wavelength meter. The wavelength meter can provide a determination of the wavelength of any one or all of the plurality of laser beams by suitable processing. Another aspect of the present invention is that one of the laser beams could be a known reference laser having a predetermined wavelength. Hence, the improved wavelength meter can provide an on-line calibration capability with the reference laser input as one of the plurality of laser beams.

  3. Wavelength meter having single mode fiber optics multiplexed inputs

    DOEpatents

    Hackel, Richard P.; Paris, Robert D.; Feldman, Mark

    1993-01-01

    A wavelength meter having a single mode fiber optics input is disclosed. The single mode fiber enables a plurality of laser beams to be multiplexed to form a multiplexed input to the wavelength meter. The wavelength meter can provide a determination of the wavelength of any one or all of the plurality of laser beams by suitable processing. Another aspect of the present invention is that one of the laser beams could be a known reference laser having a predetermined wavelength. Hence, the improved wavelength meter can provide an on-line calibration capability with the reference laser input as one of the plurality of laser beams.

  4. Saturn's aurora observed by the Cassini camera at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Dyudina, Ulyana A.; Ingersoll, Andrew P.; Ewald, Shawn P.; Wellington, Danika

    2016-01-01

    The first observations of Saturn's visible-wavelength aurora were made by the Cassini camera. The aurora was observed between 2006 and 2013 in the northern and southern hemispheres. The color of the aurora changes from pink at a few hundred km above the horizon to purple at 1000-1500 km above the horizon. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with laboratory simulated auroras. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs between 70° and 80° latitude north and between 65° and 80° latitude south, which sometimes spiral around the pole, and sometimes form double arcs. A large 10,000-km-scale longitudinal brightness structure persists for more than 100 h. This structure rotates approximately together with Saturn. On top of the large steady structure, the auroras brighten suddenly on the timescales of a few minutes. These brightenings repeat with a period of ∼1 h. Smaller, 1000-km-scale structures may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The persistence of nearly-corotating large bright longitudinal structure in the auroral oval seen in two movies spanning 8 and 11 rotations gives an estimate on the period of 10.65 ± 0.15 h for 2009 in the northern oval and 10.8 ± 0.1 h for 2012 in the southern oval. The 2009 north aurora period is close to the north branch of Saturn Kilometric Radiation (SKR) detected at that time.

  5. Tuning the wavelength of spoof plasmons by adjusting the impedance contrast in an array of penetrable inclusions

    NASA Astrophysics Data System (ADS)

    Cordero, M. L.; Maurel, A.; Mercier, J.-F.; Félix, S.; Barra, F.

    2015-08-01

    While spoof plasmons have been proposed in periodic arrays of sound-hard inclusions, we show that they also exist when inclusions are penetrable. Moreover, we show that their wavelength can be tuned by the impedance mismatch between the inclusion material and the surrounding medium, beyond the usual effect of filling fraction in the array. It is demonstrated that sound-soft materials increase the efficiency in the generation of sub-wavelength plasmons, with much lower wavelengths than sound-hard materials and than a homogeneous slab. An application to the generation of acoustic spoof plasmons by an ultra compact array of air/polydimethylsiloxane inclusions in water is proposed with plasmon wavelength tunable up to deep sub-wavelength scales.

  6. Accurate Spectral Fits of Jupiter's Great Red Spot: VIMS Visual Spectra Modelled with Chromophores Created by Photolyzed Ammonia Reacting with Acetyleneχ±

    NASA Astrophysics Data System (ADS)

    Baines, Kevin; Sromovsky, Lawrence A.; Fry, Patrick M.; Carlson, Robert W.; Momary, Thomas W.

    2016-10-01

    We report results incorporating the red-tinted photochemically-generated aerosols of Carlson et al (2016, Icarus 274, 106-115) in spectral models of Jupiter's Great Red Spot (GRS). Spectral models of the 0.35-1.0-micron spectrum show good agreement with Cassini/VIMS near-center-meridian and near-limb GRS spectra for model morphologies incorporating an optically-thin layer of Carlson (2016) aerosols at high altitudes, either at the top of the tropospheric GRS cloud, or in a distinct stratospheric haze layer. Specifically, a two-layer "crème brûlée" structure of the Mie-scattering Carlson et al (2016) chromophore attached to the top of a conservatively scattering (hereafter, "white") optically-thick cloud fits the spectra well. Currently, best agreement (reduced χ2 of 0.89 for the central-meridian spectrum) is found for a 0.195-0.217-bar, 0.19 ± 0.02 opacity layer of chromophores with mean particle radius of 0.14 ± 0.01 micron. As well, a structure with a detached stratospheric chromophore layer ~0.25 bar above a white tropospheric GRS cloud provides a good spectral match (reduced χ2 of 1.16). Alternatively, a cloud morphology with the chromophore coating white particles in a single optically- and physically-thick cloud (the "coated-shell model", initially explored by Carlson et al 2016) was found to give significantly inferior fits (best reduced χ2 of 2.9). Overall, we find that models accurately fit the GRS spectrum if (1) most of the optical depth of the chromophore is in a layer near the top of the main cloud or in a distinct separated layer above it, but is not uniformly distributed within the main cloud, (2) the chromophore consists of relatively small, 0.1-0.2-micron-radius particles, and (3) the chromophore layer optical depth is small, ~ 0.1-0.2. Thus, our analysis supports the exogenic origin of the red chromophore consistent with the Carlson et al (2016) photolytic production mechanism rather than an endogenic origin, such as upwelling of material

  7. Bulk acousto-optic wavelength agile filter module for a wavelength-multiplexed optical scanner.

    PubMed

    Yaqoob, Zahid; Riza, Nabeel A

    2005-05-01

    An acousto-optic tunable filter-based wavelength-selection module with features optimized for a wavelength-multiplexed optical scanner (W-MOS) is proposed and demonstrated. The W-MOS produces high-speed multiple scan beams if it is engaged with an agile tunable source with multiwavelength generation capability. In particular, the proposed fiber-connected module features high-speed, low-loss, narrow-linewidth, and single-multiple wavelength selection by means of radio frequency drive signal control for single- or multiple-beam scan operations. The unique module offers input laser beam power control that in turn delivers the desired scanned laser beam power shaping. Experimental results match module design theory and demonstrate a fast 5.4-micros wavelength selection speed, a low (1.53-dB) fiber-to-fiber optical insertion loss, a 5.55-nm 3-dB spectral width, and a 1500-1600-nm agile wavelength operational band.

  8. On the Capability of Artificial Neural Networks to Compensate Nonlinearities in Wavelength Sensing

    PubMed Central

    Hafiane, Mohamed Lamine; Dibi, Zohir; Manck, Otto

    2009-01-01

    An intelligent sensor for light wavelength readout, suitable for visible range optical applications, has been developed. Using buried triple photo-junction as basic pixel sensing element in combination with artificial neural network (ANN), the wavelength readout with a full-scale error of less than 1.5% over the range of 400 to 780 nm can be achieved. Through this work, the applicability of the ANN approach in optical sensing is investigated and compared with conventional methods, and a good compromise between accuracy and the possibility for on-chip implementation was thus found. Indeed, this technique can serve different purposes and may replace conventional methods. PMID:22574051

  9. Young's experiment with a double slit of sub-wavelength dimensions.

    PubMed

    Lee, Kanghee; Lim, Jongseok; Ahn, Jaewook

    2013-08-12

    We report that the interference pattern of Young's double-slit experiment changes as a function of polarization in the sub-wavelength diffraction regime. Experiments carried out with terahertz time-domain spectroscopy reveal that diffracted waves from sub-wavelength-scale slits exhibit either positive or negative phase shift with respect to Gouy phase depending on the polarization. Theoretical explanation based on the induction of electric current and magnetic dipole in the vicinity of the slits shows an excellent agreement with the experimental results.

  10. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    PubMed

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  11. Controlled blueshift of the resonant wavelength in porous silicon microcavities using ion irradiation

    SciTech Connect

    Mangaiyarkarasi, D.; Breese, M. B. H.; Ow, Y. S.; Vijila, C.

    2006-07-10

    High-energy focused proton beam irradiation has been used to controllably blueshift the resonant wavelength of porous silicon microcavities in heavily doped p-type wafers. Irradiation results in an increased resistivity, hence a locally reduced rate of anodization. Irradiated regions are consequently thinner and of a higher refractive index than unirradiated regions, and the microcavity blueshift arises from a net reduction in the optical thickness of each porous layer. Using this process wafers are patterned on a micrometer lateral scale with microcavities tuned to different resonant wavelengths, giving rise to high-resolution full-color reflection images over the full visible spectrum.

  12. Dual-wavelength moisture meter for clay

    NASA Astrophysics Data System (ADS)

    Norgia, Michele; Pesatori, Alessandro

    2012-10-01

    An optical sensor for measuring the moisture level of clay has been realized by a couple of telecommunications lasers at 1300 and 1550 nm. The sensor can operate directly during building material production. The measurement principle is based on the measurement of the optical reflection at different wavelengths in the infrared region. Custom low-noise electronics allows rejecting disturbances of ambient light, and a digital processing makes the system independent on the clay distance. By means of a proper calibration, the sensor can monitor the moisture level during brick production, without moving parts or optical filters.

  13. High performance optical wavelength multiplexer-demultiplexer.

    PubMed

    Dobrowolski, J A; Hara, E H; Sullivan, B T; Waldorf, A J

    1992-07-01

    The principle of an optical wavelength multiplexer-demultiplexer is described in which the signals undergo repeated reflections from special filter elements that can be designed for a wide range of cross-talk ratios. The insertion losses of these units can be quite small and they can be implemented to provide simultaneous multichannel two-way transmission. In a preliminary investigation of an experimental prototype an insertion loss of 0.5 dB and a cross talk of -35 dB were demonstrated. The multiplexer-demultiplexer is expected to have a long life and high reliability.

  14. Wavelength de-multiplexing metasurface hologram

    PubMed Central

    Wang, Bo; Quan, Baogang; He, Jingwen; Xie, Zhenwei; Wang, Xinke; Li, Junjie; Kan, Qiang; Zhang, Yan

    2016-01-01

    A wavelength de-multiplexing metasurface hologram composed of subwavelength metallic antennas is designed and demonstrated experimentally in the terahertz (THz) regime. Different character patterns are generated at the separated working frequencies 0.50 THz and 0.63 THz which determine a narrow frequency bandwidth of 130 GHz. The two working frequencies are around the central resonance frequency of the antennas where antennas behave strong wavefront modulation. Each antenna is fully utilized to control the wavefront of the metasurface at different frequencies by an optimization algorithm. The results demonstrate a candidate way to design multi-colors optical display elements. PMID:27752118

  15. Quasi-optical diplexer for millimeter wavelengths.

    PubMed

    Payne, J M; Wordeman, M R

    1978-12-01

    A quasi-optical diplexer for injection of signal and local oscillator frequencies into a mixer at millimeter wave-lengths is described. The diplexer accepts both image and signal bands, presents low loss at both the signal and local oscillator frequencies and rejects local oscillator noise at the signal frequency. The configuration of the device makes it particularly useful for Cassegrain receivers using a cooled mixer and a lens corrected feed system. The diplexer has been tested at 150 GHz on the 11-m radio telescope operated by The National Radio Astronomy Observatory in Tucson, Arizona.

  16. Multi-wavelength compressive computational ghost imaging

    NASA Astrophysics Data System (ADS)

    Welsh, Stephen S.; Edgar, Matthew P.; Jonathan, Phillip; Sun, Baoqing; Padgett, Miles J.

    2013-03-01

    The field of ghost imaging encompasses systems which can retrieve the spatial information of an object through correlated measurements of a projected light field, having spatial resolution, and the associated reflected or transmitted light intensity measured by a photodetector. By employing a digital light projector in a computational ghost imaging system with multiple spectrally filtered photodetectors we obtain high-quality multi-wavelength reconstructions of real macroscopic objects. We compare different reconstruction algorithms and reveal the use of compressive sensing techniques for achieving sub-Nyquist performance. Furthermore, we demonstrate the use of this technology in non-visible and fluorescence imaging applications.

  17. Quantum cascade lasers designed toward shorter wavelengths

    NASA Astrophysics Data System (ADS)

    Xu, Jilian; Liu, Lei; Li, Bing Hui; Zhang, Zhenzhong; Ma, Jian; Liu, Kewei; He, Jun; Shen, D. Z.

    2016-02-01

    Quantum cascade lasers (QCLs) are normally based on one-dimensional confined quantum wells. In this scheme, it is still a challenge to produce lasing with a frequency higher than mid-infrared. Here, we discuss the possibility to extend the spectral range of QCLs to the higher frequency region by adding another dimensional confinement. Taking the ZnO/MgO system as an example, we demonstrate theoretically that such a two-dimensional confined QCL can operate at wavelengths from the near-infrared λ =2.95 μm, 1.57 μm, 1.13 μm to the visible 734 nm.

  18. Quantum cascade lasers designed toward shorter wavelengths.

    PubMed

    Xu, Jilian; Liu, Lei; Li, Bing Hui; Zhang, Zhenzhong; Ma, Jian; Liu, Kewei; He, Jun; Shen, D Z

    2016-02-17

    Quantum cascade lasers (QCLs) are normally based on one-dimensional confined quantum wells. In this scheme, it is still a challenge to produce lasing with a frequency higher than mid-infrared. Here, we discuss the possibility to extend the spectral range of QCLs to the higher frequency region by adding another dimensional confinement. Taking the ZnO/MgO system as an example, we demonstrate theoretically that such a two-dimensional confined QCL can operate at wavelengths from the near-infrared [Formula: see text] μm, 1.57 μm, 1.13 μm to the visible 734 nm.

  19. Two wavelength division multiplexing WAN trials

    SciTech Connect

    Lennon, W.J.; Thombley, R.L.

    1995-01-20

    Lawrence Livermore National Laboratory, as a super-user, supercomputer, and super-application site, is anticipating the future bandwidth and protocol requirements necessary to connect to other such sites as well as to connect to remote-sited control centers and experiments. In this paper the authors discuss their vision of the future of Wide Area Networking, describe the plans for a wavelength division multiplexed link connecting Livermore with the University of California at Berkeley and describe plans for a transparent, {approx} 10 Gb/s ring around San Francisco Bay.

  20. Wavelength Shifters and Interactions of EDTA with Acrylic & LAB

    NASA Astrophysics Data System (ADS)

    Mohan, Yuvraj; SNO+ Collaboration

    2014-09-01

    The SNO + experiment, an upgrade to the Sudbury Neutrino Observatory, will use linear alkyl-benzene (LAB) liquid scintillator to probe new physics, including 0 νββ decay. Event detection efficiency is heavily affected by radioactive backgrounds, two sources being Rn-222 and Po-210 daughters, some of which has become embedded in the SNO + acrylic vessel after years underground. The leading candidate for polonium leaching is Ethylenediaminetetraacetic acid (EDTA). Before deployment on-site, EDTA's effects on the mechanical integrity of acrylic must be determined. It also must not be soluble in LAB or must be removed before scintillator fill of the vessel, as its presence would result in reduced light yield due to scattering. It was found that EDTA had negligible effects on the Young's Modulus of acrylic. EDTA is also slightly soluble in LAB, but can be completely removed by rinsing with water. Additionally, the study of the light yield and alpha/beta timing profiles of two wavelength shifters - bisMSB and perylene - is critical to determining which should be added to the 0 νββ isotope (tellurium) LAB cocktail. Small-scale results hint that perylene might be better, but this is being confirmed with larger-scale tests. The SNO + experiment, an upgrade to the Sudbury Neutrino Observatory, will use linear alkyl-benzene (LAB) liquid scintillator to probe new physics, including 0 νββ decay. Event detection efficiency is heavily affected by radioactive backgrounds, two sources being Rn-222 and Po-210 daughters, some of which has become embedded in the SNO + acrylic vessel after years underground. The leading candidate for polonium leaching is Ethylenediaminetetraacetic acid (EDTA). Before deployment on-site, EDTA's effects on the mechanical integrity of acrylic must be determined. It also must not be soluble in LAB or must be removed before scintillator fill of the vessel, as its presence would result in reduced light yield due to scattering. It was found that EDTA

  1. Influence of spectral properties of wavelength-locked and wavelength-unlocked diode laser on fiber laser performances

    NASA Astrophysics Data System (ADS)

    Huang, Zhihua; Tang, Xuan; Zhao, Pengfei; Li, Zebiao; Li, Chengyu; Li, Qi; Guo, Chao; Lin, Honghuan; Wang, Jianjun; Jing, Feng

    2016-07-01

    The influence of the spectral properties of laser diode (LD) pump source, i.e. central wavelength and linewidth, on the fiber laser performances are studied. The absorption degradation ratio (ADR) is introduced and evaluated as a guide for pump selection and fiber laser design. The spectra of wavelength-locked and wavelength-unlocked LDs are measured and they are used for fiber laser amplification. The results show that the efficiency of the wavelength-locked LDs is higher than that of the wavelength-unlocked LDs at full current but the residual pump power of wavelength-locked LDs can be much higher at lower current because of the side band.

  2. Wavelength dependence of aerosol backscatter coefficients obtained by multiple wavelength Lidar measurements

    NASA Technical Reports Server (NTRS)

    Sasano, Y.; Browell, E. V.

    1986-01-01

    Aerosols are often classified into several general types according to their origins and composition, such as maritime, continental, and stratospheric aerosols, and these aerosol types generally have different characteristics in chemical and physical properties. The present study aims at demonstrating the potential for distinguishing these aerosol types by the wavelength dependence of their backscatter coefficients obtained from quantitative analyses of multiple wavelength lidar signals. Data from the NASA Airborne Differential Abosrption lidar (DIAL) S ystems, which can measure aerosol backscatter profiles at wavelenghts of 300, 600, and 1064 nm and ozone profiles of backscatter coefficients for these three wavelength were derived from the observations of aerosols of different types. Observations were performed over the Atlantic Ocean, the Southwestern United States, and French Guyana.

  3. Laser-to-electricity energy converter for short wavelengths

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y. C. M.

    1975-01-01

    Short-wavelength energy converter can be made using Schottky barrier structure. It has wider band gap than p-n junction silicon semiconductors, and thus it has improved response at wavelengths down to and including ultraviolet region.

  4. Coherence techniques at extreme ultraviolet wavelengths

    SciTech Connect

    Chang, Chang

    2002-10-01

    The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

  5. SHORT-WAVELENGTH MAGNETIC BUOYANCY INSTABILITY

    SciTech Connect

    Mizerski, K. A.; Davies, C. R.; Hughes, D. W. E-mail: tina@maths.leeds.ac.uk

    2013-04-01

    Magnetic buoyancy instability plays an important role in the evolution of astrophysical magnetic fields. Here we revisit the problem introduced by Gilman of the short-wavelength linear stability of a plane layer of compressible isothermal fluid permeated by a horizontal magnetic field of strength decreasing with height. Dissipation of momentum and magnetic field is neglected. By the use of a Rayleigh-Schroedinger perturbation analysis, we explain in detail the limit in which the transverse horizontal wavenumber of the perturbation, denoted by k, is large (i.e., short horizontal wavelength) and show that the fastest growing perturbations become localized in the vertical direction as k is increased. The growth rates are determined by a function of the vertical coordinate z since, in the large k limit, the eigenmodes are strongly localized in the vertical direction. We consider in detail the case of two-dimensional perturbations varying in the directions perpendicular to the magnetic field, which, for sufficiently strong field gradients, are the most unstable. The results of our analysis are backed up by comparison with a series of initial value problems. Finally, we extend the analysis to three-dimensional perturbations.

  6. Wavelength-band-tuning photodiodes by using various metallic nanoparticles.

    PubMed

    Hwang, J D; Chan, Y D; Chou, T C

    2015-11-20

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD. PMID:26508114

  7. Wavelength-band-tuning photodiodes by using various metallic nanoparticles.

    PubMed

    Hwang, J D; Chan, Y D; Chou, T C

    2015-11-20

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD.

  8. Wavelength-band-tuning photodiodes by using various metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Hwang, J. D.; Chan, Y. D.; Chou, T. C.

    2015-11-01

    Wavelength-band tuning was easily achieved in this work by depositing various metallic nanoparticles (NPs) on silicon p-n junction photodiodes (PDs). The normalization spectrum of the PDs deposited with gold (Au) NPs reveals a high-wavelength pass characteristic; the PDs with silver (Ag) NPs coating behave as a low-wavelength pass, and the PDs with Au/Ag bimetallic NPs appear as a band-wavelength pass PD with a full width at half maximum of 450 ∼ 630 nm. The issue of wavelength-band tuning is due to the different plasmonic resonance wavelengths associated with various metallic NPs. The extinction plot shows the Au NPs have a longer resonant wavelength of about 545 nm, leading to the incident light with a wavelength near or longer than 545 nm scattered by the Au NPs, hence a high-wavelength pass PD. The PDs with Ag NPs, due to the Ag NPs, exhibit a short resonant wavelength of 430 nm, and the short-wavelength incident light is absorbed near the silicon (Si) surface, where the Ag NPs is atop it. The shorter-wavelength incident light is enhanced by the plasmonic resonance of Ag NPs, making a low-wavelength PD. The Au/Ag NPs presents a resonant wavelength of 500 nm between the Au and Ag NPs. For the incident light with a wavelength close to 500 nm, a constructive interference causes a substantial increase in the local electromagnetic field, hence leading to a band-wavelength pass PD.

  9. Wavelength Calibration Accuracy for the STIS CCD and MAMA Modes

    NASA Astrophysics Data System (ADS)

    Pascucci, Ilaria; Hodge, Phil; Proffitt, Charles R.; Ayres, T.

    2011-03-01

    Two calibration programs were carried out to determine the accuracy of the wavelength solutions for the most used STIS CCD and MAMA modes after Servicing Mission 4. We report here on the analysis of this dataset and show that the STIS wavelength solution has not changed after SM4. We also show that a typical accuracy for the absolute wavelength zero-points is 0.1 pixels while the relative wavelength accuracy is 0.2 pixels.

  10. Wavelength-Division Multiplexing Of Bipolar Digital Signals

    NASA Technical Reports Server (NTRS)

    Gibbons, Ronnie D.; Ubele, John L., II

    1994-01-01

    In system, bipolar digital data transmitted by use of wavelength-division multiplexing on single optical fiber. Two different wavelengths used to transmit pulses signifying "positive" or "negative" bipolar digital data. Simultaneous absence of pulses at both wavelengths signifies digital "zero."

  11. Two-wavelength operation of the nonlinear fiber loop mirror.

    PubMed

    Blow, K J; Doran, N J; Nayar, B K; Nelson, B P

    1990-02-15

    We describe the two-wavelength operation of the nonlinear fiber loop mirror. In this mode of operation a high-power signal at one wavelength switches a low-power signal at another wavelength. This device is investigated both theoretically and experimentally. The experimental results show that the nonlinear loop mirror performs as an optical modulator that consists of all-fiber components.

  12. Dual polarized long wavelength radar for discrimination of agricultural land use

    NASA Technical Reports Server (NTRS)

    Waite, W. P.; Macdonald, H. C.; Tolman, D. N.; Barlow, C. A.; Borengasser, M.

    1978-01-01

    The scattered return of imaging radars is primarily sensitive to target structure or roughness and to composition of complex permittivity. The relative degree of penetration, or the depth of material to which the return is sensitive, also varies directly with the wavelength. Where vegetation can be eliminated as a factor, the surface return may be analyzed for variations in roughness or composition (primarily moisture content). L-band (25-cm) imagery has provided evidence that long-wavelength systems with improved penetration capability have the potential for minimizing the vegetation contribution and enhancing the surface return variations. However, the increased wavelength increases the sensitivity to large-scale structure. In the present paper, it is shown that addition of a cross polarized channel enables the interpreter to distinguish vegetation and orientation perturbations in the surface return.

  13. Wavelength-selective visible-light detector based on integrated graphene transistor and surface plasmon coupler

    NASA Astrophysics Data System (ADS)

    Smith, Christian W.; Maukonen, Doug; Peale, R. E.; Fredricksen, C. J.; Ishigami, M.; Cleary, J. W.

    2014-06-01

    We have invented a novel photodetector by mating a surface plasmon resonance coupler with a graphene field effect transistor. The device enables wavelength selectivity for spectral sensing applications. Surface plasmon polaritons (SPPs) are generated in a 50 nm thick Ag film on the surface of a prism in the Kretschmann configuration positioned 500 nm from a graphene FET. Incident photons of a given wavelength excite SPPs at a specific incidence angle. These SPP fields excite a transient current whose amplitude follows the angular resonance spectrum of the SPP absorption feature. Though demonstrated first at visible wavelengths, the approach can be extended far into the infrared. We also demonstrate that the resonant current is strongly modulated by gate bias applied to the FET, providing a clear path towards large-scale spectral imagers with locally addressable pixels.

  14. Multi-Wavelength Views of Messier 81

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site] Click on individual images below for larger view

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this image from NASA's Spitzer Space Telescope. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.

    The main image is a composite mosaic obtained with the multiband imaging photometer for Spitzer and the infrared array camera. Thermal infrared emission at 24 microns detected by the photometer (red, bottom left inset) is combined with camera data at 8.0 microns (green, bottom center inset) and 3.6 microns (blue, bottom right inset).

    A visible-light image of Messier 81, obtained at Kitt Peak National Observatory, a ground-based telescope, is shown in the upper right inset. Both the visible-light picture and the 3.6-micron near-infrared image trace the distribution of stars, although the Spitzer image is virtually unaffected by obscuring dust. Both images reveal a very smooth stellar mass distribution, with the spiral arms relatively subdued.

    As one moves to longer wavelengths, the spiral arms become the dominant feature of the galaxy. The 8-micron emission is dominated by infrared light radiated by hot dust that has been heated by nearby luminous stars. Dust in the galaxy is bathed by ultraviolet and visible light from nearby stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles are composed of silicates (chemically similar to beach sand), carbonaceous grains and polycyclic aromatic hydrocarbons and

  15. Dynamic sensor interrogation using wavelength-swept laser with a polygon-scanner-based wavelength filter.

    PubMed

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-07-29

    We report a high-speed (~2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement.

  16. Dynamic Sensor Interrogation Using Wavelength-Swept Laser with a Polygon-Scanner-Based Wavelength Filter

    PubMed Central

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-01-01

    We report a high-speed (∼2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement. PMID:23899934

  17. Multi-wavelength synchronous pulse burst generation with a wavelength selective switch.

    PubMed

    Roelens, Michaël A; Bolger, Jeremy A; Williams, David; Eggleton, Benjamin J

    2008-07-01

    We demonstrate simultaneous pulse-shaping at different ports of a rapidly tunable wavelength selective switch at a base rate of 40 GHz, based on Fourier-domain pulse shaping. Various pulse bursts are generated and accurately characterized with a linear spectrographic method.

  18. Dynamic sensor interrogation using wavelength-swept laser with a polygon-scanner-based wavelength filter.

    PubMed

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-01-01

    We report a high-speed (~2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement. PMID:23899934

  19. Sub-wavelength nanofluidics in photonic crystal sensors.

    PubMed

    Huang, Min; Yanik, Ahmet Ali; Chang, Tsung-Yao; Altug, Hatice

    2009-12-21

    We introduce a novel sensor scheme combining nano-photonics and nano-fluidics on a single platform through the use of free-standing photonic crystals. By harnessing nano-scale openings, we theoretically and experimentally demonstrate that both fluidics and light can be manipulated at sub-wavelength scales. Compared to the conventional fluidic channels, we actively steer the convective flow through the nanohole openings for effective delivery of the analytes to the sensor surface. We apply our method to detect refractive index changes in aqueous solutions. Bulk measurements indicate that active delivery of the convective flow results in better sensitivities. The sensitivity of the sensor reaches 510 nm/RIU for resonance located around 850 nm with a line-width of approximately 10 nm in solution. Experimental results are matched very well with numerical simulations. We also show that cross-polarization measurements can be employed to further improve the detection limit by increasing the signal-to-noise ratio.

  20. Short wavelength topography on the inner-core boundary

    PubMed Central

    Cao, Aimin; Masson, Yder; Romanowicz, Barbara

    2007-01-01

    Constraining the topography of the inner-core boundary is important for studies of core–mantle coupling and the generation of the geodynamo. We present evidence for significant temporal variability in the amplitude of the inner core reflected phase PKiKP for an exceptionally high-quality earthquake doublet, observed postcritically at the short-period Yellowknife seismic array (YK), which occurred in the South Sandwich Islands within a 10-year interval (1993/2003). This observation, complemented by data from several other doublets, indicates the presence of topography at the inner-core boundary, with a horizontal wavelength on the order of 10 km. Such topography could be sustained by small-scale convection at the top of the inner core and is compatible with a rate of super rotation of the inner core of ≈0.1–0.15° per year. In the absence of inner-core rotation, decadal scale temporal changes in the inner-core boundary topography would provide an upper bound on the viscosity at the top of the inner core. PMID:17190798

  1. SARAS MEASUREMENT OF THE RADIO BACKGROUND AT LONG WAVELENGTHS

    SciTech Connect

    Patra, Nipanjana; Subrahmanyan, Ravi; Sethi, Shiv; Shankar, N. Udaya; Raghunathan, A.

    2015-03-10

    SARAS is a correlation spectrometer connected to a frequency independent antenna that is purpose-designed for precision measurements of the radio background at long wavelengths. The design, calibration, and observing strategies admit solutions for the internal additive contributions to the radiometer response, and hence a separation of these contaminants from the antenna temperature. We present here a wideband measurement of the radio sky spectrum by SARAS that provides an accurate measurement of the absolute brightness and spectral index between 110 and 175 MHz. Accuracy in the measurement of absolute sky brightness is limited by systematic errors of magnitude 1.2%; errors in calibration and in the joint estimation of sky and system model parameters are relatively smaller. We use this wide-angle measurement of the sky brightness using the precision wide-band dipole antenna to provide an improved absolute calibration for the 150 MHz all-sky map of Landecker and Wielebinski: subtracting an offset of 21.4 K and scaling by a factor of 1.05 will reduce the overall offset error to 8 K (from 50 K) and scale error to 0.8% (from 5%). The SARAS measurement of the temperature spectral index is in the range −2.3 to −2.45 in the 110–175 MHz band and indicates that the region toward the Galactic bulge has a relatively flatter index.

  2. Basin-Wavelength Equatorial Deep Jet Signals Across Three Oceans

    NASA Astrophysics Data System (ADS)

    Youngs, M. K.; Johnson, G. C.

    2015-12-01

    Equatorial Deep Jets (EDJs) are equatorially trapped, stacked, zonal currents that reverse direction every few hundred meters in depth throughout much of the water column. This study evaluates their structure observationally in all three oceans using new high vertical resolution Argo float conductivity-temperature-depth (CTD) instrument profiles from 2010--2014 augmented with historical shipboard CTD from 1972--2014 and lower vertical resolution Argo float profiles from 2007--2014. Vertical strain of density is calculated from the profiles and analyzed in a stretched vertical coordinate system determined from the mean vertical density structure. The power spectra of vertical strain in each basin are analyzed using a wavelet decomposition. In the Indian and Pacific oceans, there are two distinct peaks in the power spectra, one Kelvin-wave-like and the other entirely consistent with the dispersion relation of a linear first-meridional-mode equatorial Rossby wave. In the Atlantic Ocean, the first-meridional-mode Rossby wave signature is very strong, and dominates. In all three ocean basins Rossby-wave-like signatures are coherent across the basin width, and appear to have wavelengths the scale of the basin width, with periods of about 5 years in the Indian and Atlantic oceans and about 12 years in the Pacific Ocean. Their observed meridional scales are about 1.5 times the linear theoretical values. Their phase propagation is downward with time, implying upward energy propagation if linear wave dynamics hold.

  3. Tunable optical tweezers for wavelength-dependent measurements

    PubMed Central

    Hester, Brooke; Campbell, Gretchen K.; López-Mariscal, Carlos; Filgueira, Carly Levin; Huschka, Ryan; Halas, Naomi J.; Helmerson, Kristian

    2012-01-01

    Optical trapping forces depend on the difference between the trap wavelength and the extinction resonances of trapped particles. This leads to a wavelength-dependent trapping force, which should allow for the optimization of optical tweezers systems, simply by choosing the best trapping wavelength for a given application. Here we present an optical tweezer system with wavelength tunability, for the study of resonance effects. With this system, the optical trap stiffness is measured for single trapped particles that exhibit either single or multiple extinction resonances. We include discussions of wavelength-dependent effects, such as changes in temperature, and how to measure them. PMID:22559522

  4. Spin and wavelength multiplexed nonlinear metasurface holography

    NASA Astrophysics Data System (ADS)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  5. Spin and wavelength multiplexed nonlinear metasurface holography

    PubMed Central

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-01-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam–Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption. PMID:27306147

  6. Achromatic Metasurface Lens at Telecommunication Wavelengths.

    PubMed

    Khorasaninejad, Mohammadreza; Aieta, Francesco; Kanhaiya, Pritpal; Kats, Mikhail A; Genevet, Patrice; Rousso, David; Capasso, Federico

    2015-08-12

    Nanoscale optical resonators enable a new class of flat optical components called metasurfaces. This approach has been used to demonstrate functionalities such as focusing free of monochromatic aberrations (i.e., spherical and coma), anomalous reflection, and large circular dichroism. Recently, dielectric metasurfaces that compensate the phase dispersion responsible for chromatic aberrations have been demonstrated. Here, we utilize an aperiodic array of coupled dielectric nanoresonators to demonstrate a multiwavelength achromatic lens. The focal length remains unchanged for three wavelengths in the near-infrared region (1300, 1550, and 1800 nm). Experimental results are in agreement with full-wave simulations. Our findings are an essential step toward a realization of broadband flat optical elements.

  7. AJ/LPI at millimeter wavelengths

    NASA Astrophysics Data System (ADS)

    Tiffany, G. B.; Bleck, D. T.; Boatman, R. K.

    The AJ/LPI advantages of millimeter wavelength communication at or near the 60-GHz oxygen line have been apparent to researchers for many years. Realizing the full extent of these advantages in a system appropriate for field operation requires more than simply designing a conventional communications link for operation at 60 GHz. Very low sidelobe, narrow beamwidth antennas of rugged construction and the use of frequency agility and spread spectrum modulation are also necessary. Construction of short range, clear weather tactical communication systems exploiting tropospheric oxygen absorption in the 50- to 70-GHz region appears feasible with current state-of-the-art solid-state components. The critical design parameters for achieving all weather jamming resistance and covertness are frequency selection, power management, waveform design, and antenna side- and back-lobe performance.

  8. Spin and wavelength multiplexed nonlinear metasurface holography.

    PubMed

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-01-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption. PMID:27306147

  9. Innovative Long Wavelength Infrared Detector Workshop Proceedings

    NASA Technical Reports Server (NTRS)

    Grunthaner, Frank J.

    1990-01-01

    The focus of the workshop was on innovative long wavelength (lambda less than 17 microns) infrared (LWIR) detectors with the potential of meeting future NASA and DoD long-duration space application needs. Requirements are for focal plane arrays which operate near 65K using active refrigeration with mission lifetimes of five to ten years. The workshop addressed innovative concepts, new material systems, novel device physics, and current progress in relation to benchmark technology. It also provided a forum for discussion of performance characterization, producibility, reliability, and fundamental limitations of device physics. It covered the status of the incumbent HgCdTe technology, which shows encouraging progress towards LWIR arrays, and provided a snapshot of research and development in several new contender technologies.

  10. Short-wavelength ablation of solids: pulse duration and wavelength effects

    NASA Astrophysics Data System (ADS)

    Juha, Libor; Bittner, Michal; Chvostova, Dagmar; Letal, Vit; Krasa, Josef; Otcenasek, Zdenek; Kozlova, Michaela; Polan, Jiri; Prag, Ansgar R.; Rus, Bedrich; Stupka, Michal; Krzywinski, Jacek; Andrejczuk, Andrzej; Pelka, Jerzy B.; Sobierajski, Ryszard H.; Ryc, Leszek; Feldhaus, Josef; Boody, Frederick P.; Fiedorowicz, Henryk; Bartnik, Andrzej; Mikolajczyk, Janusz; Rakowski, Rafal; Kubat, P.; Pina, Ladislav; Grisham, Michael E.; Vaschenko, Georgiy O.; Menoni, Carmen S.; Rocca, Jorge J. G.

    2004-11-01

    For conventional wavelength (UV-Vis-IR) lasers delivering radiation energy to the surface of materials, ablation thresholds, ablation (etch) rates, and the quality of ablated structures often differ dramatically between short (typically nanosecond) and ultrashort (typically femtosecond) pulses. Various short-wavelength (l < 100 nm) lasers emitting pulses with durations ranging from ~ 10 fs to ~ 1 ns have recently been put into a routine operation. This makes it possible to investigate how the ablation characteristics depend on the pulse duration in the XUV spectral region. 1.2-ns pulses of 46.9-nm radiation delivered from a capillary-discharge Ne-like Ar laser (Colorado State University, Fort Collins), focused by a spherical Sc/Si multilayer-coated mirror were used for an ablation of organic polymers and silicon. Various materials were irradiated with ellipsoidal-mirror-focused XUV radiation (λ = 86 nm, τ = 30-100 fs) generated by the free-electron laser (FEL) operated at the TESLA Test Facility (TTF1 FEL) in Hamburg. The beam of the Ne-like Zn XUV laser (λ = 21.2 nm, τ < 100 ps) driven by the Prague Asterix Laser System (PALS) was also successfully focused by a spherical Si/Mo multilayer-coated mirror to ablate various materials. Based on the results of the experiments, the etch rates for three different pulse durations are compared using the XUV-ABLATOR code to compensate for the wavelength difference. Comparing the values of etch rates calculated for short pulses with those measured for ultrashort pulses, we can study the influence of pulse duration on XUV ablation efficiency. Ablation efficiencies measured with short pulses at various wavelengths (i.e. 86/46.9/21.2 nm from the above-mentioned lasers and ~ 1 nm from the double stream gas-puff Xe plasma source driven by PALS) show that the wavelength influences the etch rate mainly through the different attenuation lengths.

  11. Geometrical measurement of cardiac wavelength in reaction-diffusion models

    NASA Astrophysics Data System (ADS)

    Dupraz, Marie; Jacquemet, Vincent

    2014-09-01

    The dynamics of reentrant arrhythmias often consists in multiple wavelets propagating throughout an excitable medium. An arrhythmia can be sustained only if these reentrant waves have a sufficiently short wavelength defined as the distance traveled by the excitation wave during its refractory period. In a uniform medium, wavelength may be estimated as the product of propagation velocity and refractory period (electrophysiological wavelength). In order to accurately measure wavelength in more general substrates relevant to atrial arrhythmias (heterogeneous and anisotropic), we developed a mathematical framework to define geometrical wavelength at each time instant based on the length of streamlines following the propagation velocity field within refractory regions. Two computational methods were implemented: a Lagrangian approach in which a set of streamlines were integrated, and an Eulerian approach in which wavelength was the solution of a partial differential equation. These methods were compared in 1D/2D tissues and in a model of the left atrium. An advantage of geometrical definition of wavelength is that the wavelength of a wavelet can be tracked over time with high temporal resolution and smaller temporal variability in an anisotropic and heterogeneous medium. The results showed that the average electrophysiological wavelength was consistent with geometrical measurements of wavelength. Wavelets were however often shorter than the electrophysiological wavelength due to interactions with boundaries and other wavelets. These tools may help to assess more accurately the relation between substrate properties and wavelet dynamics in computer models.

  12. Wire grid polarizers for visible wavelengths

    NASA Astrophysics Data System (ADS)

    Johnson, Joshua Hans

    Detailed analysis of wire-grid (WG) polarizers for visible wavelengths is presented. Rigorous coupled-wave analysis (RCWA) is used to model their performance. The optimum choice of metal for the wires is identified, and the effects of different substrate indices of refraction are considered. The polarization properties are considered with changes in the physical parameters, including period, duty cycle, and wire thickness. It is shown that the performance of WG polarizers improves with increasing angle of incidence. The effect of non-square wire profiles is considered, as is the effect of adding additional dielectric layers between the wires and the substrate. The effect of metal oxide layers forming on the wires is also modeled. While most of this work concerns WG polarizers used in transmission, the performance in reflection is also discussed. Several visible-wavelength WG polarizers were fabricated at the Cornell Nanofabrication Facility (CNF) in Ithaca, NY. Electron-beam lithography was used to write the patterns for these devices, and two different methods of pattern transfer were compared. These were the lift-off method and reactive-ion etching (RIE). We found that lift-off could not produce wires thick enough for good polarization properties. RIE could produce much thicker wires with good profiles and was used for all of the experimental work presented here. Two different methods for metal film deposition, evaporation and sputtering were also compared. Films deposited by sputtering were found to have much lower indices of refraction and to not respond to etching as well. Thermally evaporated films performed much better in WG polarizers. Alternative methods for the mass-production of visible-wavelength WG polarizers are also discussed. The performance of the fabricated WG polarizers is compared to theory. When the measured physical parameters are used in RCWA to predict the performance, the measured extinction ratio is found to be much lower than the

  13. Multi-wavelength characterization of carbonaceous aerosol

    NASA Astrophysics Data System (ADS)

    Massabò, Dario; Caponi, Lorenzo; Chiara Bove, Maria; Piazzalunga, Andrea; Valli, Gianluigi; Vecchi, Roberta; Prati, Paolo

    2014-05-01

    Carbonaceous aerosol is a major component of the urban PM. It mainly consists of organic carbon (OC) and elemental carbon (EC) although a minor fraction of carbonate carbon could be also present. Elemental carbon is mainly found in the finer PM fractions (PM2.5 and PM1) and it is strongly light absorbing. When determined by optical methods, it is usually called black carbon (BC). The two quantities, EC and BC, even if both related to the refractory components of carbonaceous aerosols, do not exactly define the same PM component (Bond and Bergstrom, 2006; and references therein). Moreover, another fraction of light-absorbing carbon exists which is not black and it is generally called brown carbon (Andreae and Gelencsér, 2006). We introduce a simple, fully automatic, multi-wavelength and non-destructive optical system, actually a Multi-Wavelength Absorbance Analyzer, MWAA, to measure off-line the light absorption in Particulate Matter (PM) collected on filters and hence to derive the black and brown carbon content in the PM This gives the opportunity to measure in the same sample the concentration of total PM by gravimetric analysis, black and brown carbon, metals by, for instance, X Ray Fluorescence, and finally ions by Ion Chromatography. Up to 16 samples can be analyzed in sequence and in an automatic and controlled way within a few hours. The filter absorbance measured by MWAA was successfully validated both against a MAAP, Multi Angle Absorption Photometer (Petzold and Schönlinner, 2004), and the polar photometer of the University of Milan. The measurement of sample absorbance at three wavelengths gives the possibility to apportion different sources of carbonaceous PM, for instance fossil fuels and wood combustion. This can be done following the so called "aethalometer method" (Sandradewi et al., 2008;) but with some significant upgrades that will be discussed together the results of field campaigns in rural and urban sites. Andreae, M.O, and Gelencsér, A

  14. Efficient, high-brightness wavelength-beam-combined commercial off-the-shelf diode stacks achieved by use of a wavelength-chirped volume Bragg grating.

    PubMed

    Chann, B; Goyal, A K; Fan, T Y; Sanchez-Rubio, A; Volodin, B L; Ban, V S

    2006-05-01

    We report a method of scaling the spatial brightness from commercial off-the-shelf diode laser stacks through wavelength beam combining, by use of a linearly wavelength-chirped volume Bragg grating (VBG). Using a three-bar commercial stack of broad-area lasers and a VBG, we demonstrate 89.5 W cw of beam-combined output with a beam-combining efficiency of 75%. The output beam has a propagation factor M2 approximately 26 on the slow axis and M2 approximately 21 on the fast axis. This corresponds to a brightness of approximately 20 MW/cm2 sr. To our knowledge, this is the highest brightness broad-area diode laser system. We achieve 81% coupling efficiency into a 100 microm, 0.22 N.A. fiber.

  15. High-performance parallel processors based on star-coupled wavelength division multiplexing optical interconnects

    DOEpatents

    Deri, Robert J.; DeGroot, Anthony J.; Haigh, Ronald E.

    2002-01-01

    As the performance of individual elements within parallel processing systems increases, increased communication capability between distributed processor and memory elements is required. There is great interest in using fiber optics to improve interconnect communication beyond that attainable using electronic technology. Several groups have considered WDM, star-coupled optical interconnects. The invention uses a fiber optic transceiver to provide low latency, high bandwidth channels for such interconnects using a robust multimode fiber technology. Instruction-level simulation is used to quantify the bandwidth, latency, and concurrency required for such interconnects to scale to 256 nodes, each operating at 1 GFLOPS performance. Performance scales have been shown to .apprxeq.100 GFLOPS for scientific application kernels using a small number of wavelengths (8 to 32), only one wavelength received per node, and achievable optoelectronic bandwidth and latency.

  16. Absolute brightness temperature measurements at 3.5-mm wavelength. [of sun, Venus, Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Ulich, B. L.; Rhodes, P. J.; Davis, J. H.; Hollis, J. M.

    1980-01-01

    Careful observations have been made at 86.1 GHz to derive the absolute brightness temperatures of the sun (7914 + or - 192 K), Venus (357.5 + or - 13.1 K), Jupiter (179.4 + or - 4.7 K), and Saturn (153.4 + or - 4.8 K) with a standard error of about three percent. This is a significant improvement in accuracy over previous results at millimeter wavelengths. A stable transmitter and novel superheterodyne receiver were constructed and used to determine the effective collecting area of the Millimeter Wave Observatory (MWO) 4.9-m antenna relative to a previously calibrated standard gain horn. The thermal scale was set by calibrating the radiometer with carefully constructed and tested hot and cold loads. The brightness temperatures may be used to establish an absolute calibration scale and to determine the antenna aperture and beam efficiencies of other radio telescopes at 3.5-mm wavelength.

  17. Dual-wavelength diode laser with electrically adjustable wavelength distance at 785  nm.

    PubMed

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2016-08-15

    A spectrally adjustable monolithic dual-wavelength diode laser at 785 nm as an excitation light source for shifted excitation Raman difference spectroscopy (SERDS) is presented. The spectral distance between the two excitation wavelengths can be electrically adjusted between 0 and 2.0 nm using implemented heater elements above the distributed Bragg reflector (DBR) gratings. Output powers up to 180 mW at a temperature of 25°C were measured. The spectral width is smaller than 13 pm, limited by the spectrum analyzer. The device is well-suited for Raman spectroscopy, and the flexible spectral distance allows a target-specific adjustment of the excitation light source for shifted excitation Raman difference spectroscopy (SERDS). PMID:27519065

  18. Composite multiple wavelength laser material and multiple wavelength laser for use therewith

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor)

    1997-01-01

    A composite multiple wavelength laser material is provided and is typically constructed with a common axis of construction in the form of a rod of uniform cross-section. The rod comprises a plurality of segments of laser material bonded, e.g., diffusion bonded, to one another along the common axis. Each segment lases at a unique wavelength when excited to produce a laser emission. The segments can be made from a birefringent material doped with laser active ions. If the same birefringent host material is used for all segments, ground-state absorption losses can be reduced by terminating either end of the rod with end segments made from undoped pieces of the birefringent material.

  19. Alerting effects of short-wavelength (blue) and long-wavelength (red) lights in the afternoon.

    PubMed

    Sahin, Levent; Figueiro, Mariana G

    2013-05-27

    Light has an acute effect on neuroendocrine responses, performance, and alertness. Most studies to date have linked the alerting effects of light to its ability to suppress melatonin, which is maximally sensitive to short-wavelength light. Recent studies, however, have shown alerting effects of white or narrowband short-wavelength lights during daytime, when melatonin levels are low. While the use of light at night to promote alertness is well understood, it is important to develop an understanding of how light impacts alertness during the daytime, especially during the post-lunch hours. The aim of the current study was to investigate how 48-minute exposures to short-wavelength (blue) light (40 lux, 18.9 microWatts/cm(2) λ(max) = 470 nanometers [nm]) or long-wavelength (red) light (40 lux, 18.9 microWatts/cm(2) λ(max) = 630 nm) close to the post-lunch dip hours affect electroencephalogram measures in participants with regular sleep schedules. Power in the alpha, alpha theta, and theta ranges was significantly lower (p<0.05) after participants were exposed to red light than after they remained in darkness. Exposure to blue light reduced alpha and alpha theta power compared to darkness, but these differences did not reach statistical significance (p>0.05). The present results extend those performed during the nighttime, and demonstrate that light can be used to increase alertness in the afternoon, close to the post-lunch dip hours. These results also suggest that acute melatonin suppression is not needed to elicit an alerting effect in humans. PMID:23535242

  20. Monolithic Single-Mode DFB Laser Array with Precise Wavelength Control for Optoelectronic Integration using an Equivalent Phase Shift Method

    NASA Astrophysics Data System (ADS)

    Li, Jingsi; Cheng, Julian; Microelectronics Research Center Team

    2013-03-01

    The integrated distributed feedback (DFB) laser array is a key component in photonic integrated circuits for wavelength-division multiplexing (WDM) system. However, it is difficult to precisely control the wavelength of individual lasers. When the rear facet of the laser is coated with a high-reflectivity mirror, a random phase change is introduced that shifts the lasing wavelength, making monolithic integration of a wavelength-controlled WDM array very difficult. To solve this problem, we propose a method to precisely control the lasing wavelength of DFB lasers over a wide range by introducing an equivalent phase shift in the cavity using sampled Bragg gratings, using wafer-scale optical lithography and requiring only coarse dimension control. The wavelength can be fine-tuned by applying different DC currents. It is shown that a WDM-DFB laser array with uniform wavelength spacing can be controlled accurately in this manner. Integrated arrays of single-mode DFB lasers for WDM systems can thus be fabricated in a low-cost manner without using low-throughput e-beam lithography, and is scalable for mass-manufacturing.

  1. Detection of an IncA/C plasmid encoding VIM-4 and CMY-4 β-lactamases in Klebsiella oxytoca and Citrobacter koseri from an inpatient in a cardiac rehabilitation unit.

    PubMed

    Caltagirone, Mariasofia; Bitar, Ibrahim; Piazza, Aurora; Spalla, Melissa; Nucleo, Elisabetta; Navarra, Antonella; Migliavacca, Roberta

    2015-07-01

    A 62-year-old patient was transferred to the cardiac rehabilitation unit of the I.R.C.C.S. Fondazione S. Maugeri after undergoing a heart transplantation at the Acute Care Hospital I.R.C.C.S. S. Matteo of Pavia. On 1 August 2013 and during hospitalization in the rehabilitation unit, Klebsiella oxytoca and Citrobacter koseri clinical isolates were simultaneously recovered from the patient's preputial swab. Both the K. oxytoca and C. koseri strains were carbapenem- resistant by MicroScan System (Beckman Coulter). Carbapenem-resistant K. pneumoniae had previously been reported in the same rehabilitation facility. The aim of the study was to identify the carbapenem resistance mechanisms among the enterobacterial species recovered. Phenotypic screening tests useful to detect the β-lactamases/carbapenemases were performed. Carbapenem MICs were obtained by Etest. AmpC and MBL encoding genes were identified by PCR and sequencing. Conjugation assays and plasmid characterization were performed. Both of the K. oxytoca and C. koseri isolates were multi drug resistant, showing resistance to amoxicillin-clavulanic acid, three generation cephalosporins, ertapenem (K. oxytoca MIC, >32 mg/L; C. koseri MIC, 4 mg/L), imipenem (K. oxytoca MIC, 4 mg/L; C. koseri MIC, 12 mg/L), thrimethoprim sulphamethoxazole and gentamicin. Susceptibility was retained to fluoroquinolones, colistin and tigecycline. Molecular characterization confirmed the co-presence of blaCMY-4 and blaVIM-4 determinants in a 150 Kb transferable plasmid of IncA/C group. This case is the first detection in Italy of the K. oxytoca and C. koseri clinical isolates co-producing the CMY-4 and VIM-4 enzymes.

  2. A new algorithm for optimizing the wavelength coverage for spectroscopic studies: Spectral Wavelength Optimization Code (SWOC)

    NASA Astrophysics Data System (ADS)

    Ruchti, G. R.; Feltzing, S.; Lind, K.; Caffau, E.; Korn, A. J.; Schnurr, O.; Hansen, C. J.; Koch, A.; Sbordone, L.; de Jong, R. S.

    2016-09-01

    The past decade and a half has seen the design and execution of several ground-based spectroscopic surveys, both Galactic and Extragalactic. Additionally, new surveys are being designed that extend the boundaries of current surveys. In this context, many important considerations must be done when designing a spectrograph for the future. Among these is the determination of the optimum wavelength coverage. In this work, we present a new code for determining the wavelength ranges that provide the optimal amount of information to achieve the required science goals for a given survey. In its first mode, it utilizes a user-defined list of spectral features to compute a figure-of-merit for different spectral configurations. The second mode utilizes a set of flux-calibrated spectra, determining the spectral regions that show the largest differences among the spectra. Our algorithm is easily adaptable for any set of science requirements and any spectrograph design. We apply the algorithm to several examples, including 4MOST, showing the method yields important design constraints to the wavelength regions.

  3. Chemical analysis of uranium-niobium alloys by wavelength dispersive spectroscopy at the sigma complex

    SciTech Connect

    Papin, Pallas A.

    2012-06-01

    Uranium-niobium alloys play an important role in the nation's nuclear stockpile. It is possible to chemically quantify this alloy at a micron scale by using a technique know as wavelength dispersive spectroscopy. This report documents how this technique was used and how it is possible to reproduce measurements of this type. Discussion regarding the accuracy and precision of the measurements, the development of standards, and the comparison of different ways to model the matrices are all presented.

  4. Atmospheric turbulence power spectral measurements to long wavelengths for several meteorological conditions

    NASA Technical Reports Server (NTRS)

    Rhyne, R. H.; Murrow, H. N.; Sidwell, K.

    1976-01-01

    Use of power spectral design techniques for supersonic transports requires accurate definition of atmospheric turbulence in the long wavelength region below the knee of the power spectral density function curve. Examples are given of data obtained from a current turbulence flight sampling program. These samples are categorized as (1) convective, (2) wind shear, (3) rotor, and (4) mountain-wave turbulence. Time histories, altitudes, root-mean-square values, statistical degrees of freedom, power spectra, and integral scale values are shown and discussed.

  5. Features of the long-wavelength impurity photoconductivity spectrum in compensated germanium

    SciTech Connect

    Druzhinin, Y.P.; Chirkova, E.G.

    1995-09-01

    This paper discusses the impurity photoconductivity spectra of compensated Ge: (Cu, Sb) in the photoheating regime, in which the photon energy is comparable to the scale of the random potential well, and the temperature is 4.2 K. Three sections are distinguished in the long-wavelength cutoff region, corresponding to different energy relaxation and charge-carrier transport mechanisms, including a mechanism that involves the participation of optical phonons. 6 refs., 1 fig.

  6. Propagation of Long-Wavelength Nonlinear Slow Sausage Waves in Stratified Magnetic Flux Tubes

    NASA Astrophysics Data System (ADS)

    Barbulescu, M.; Erdélyi, R.

    2016-05-01

    The propagation of nonlinear, long-wavelength, slow sausage waves in an expanding magnetic flux tube, embedded in a non-magnetic stratified environment, is discussed. The governing equation for surface waves, which is akin to the Leibovich-Roberts equation, is derived using the method of multiple scales. The solitary wave solution of the equation is obtained numerically. The results obtained are illustrative of a solitary wave whose properties are highly dependent on the degree of stratification.

  7. Early Results from the Long Wavelength Array

    NASA Astrophysics Data System (ADS)

    Taylor, Gregory B.; LWA Collaboration

    2012-01-01

    The Long Wavelength Array (LWA) will be a new multi-purpose radio telescope operating in the frequency range 10-88 MHz. Scientific programs include pulsars, supernova remnants, general transient searches, radio recombination lines, solar and Jupiter bursts, investigations into the "dark ages" using redshifted hydrogen, and ionospheric phenomena. Upon completion, LWA will consist of 53 phased array "stations” distributed accross a region over 400 km in diameter. Each station consists of 256 pairs of dipole-type antennas whose signals are formed into beams, with outputs transported to a central location for high-resolution aperture synthesis imaging. The resulting image sensitivity is estimated to be a few mJy (5sigma, 8 MHz, 2 polarizations, 1 h, zenith) from 20-80 MHz; with angular resolution of a few arcseconds. Additional information is online at http://lwa.unm.edu. Partners in the LWA project include LANL, JPL, NRAO, NRL, UNM, NMT, and Virginia Tech. The first station of the LWA, called "LWA1", is located near the center of the EVLA and has recently begun scientific operations. The LWA1 images the sky in realtime using the "transient buffer - narrowband” (TBN) system which is operational with 257 dipoles, and a bandwidth of 70 kHz. The LWA1 can also form up to 4 beams on the sky simultaneously with 16 MHz bandwidth in each of two tuning and full polarization. Early results include observations of pulsars, the Sun, and Jupiter.

  8. Array of Bolometers for Submillimeter- Wavelength Operation

    NASA Technical Reports Server (NTRS)

    Bock, James; Turner, Anthony

    2007-01-01

    A feed-horn-coupled monolithic array of micromesh bolometers is undergoing development for use in a photometric camera. The array is designed for conducting astrophysical observations in a wavelength band centered at 350 m. The bolometers are improved versions of previously developed bolometers comprising metalized Si3N4 micromesh radiation absorbers coupled with neutron- transmutation-doped Ge thermistors. Incident radiation heats the absorbers above a base temperature, changing the electrical resistance of each thermistor. In the present array of improved bolometers (see figure), the thermistors are attached to the micromesh absorbers by indium bump bonds and are addressed by use of lithographed, vapor-deposited electrical leads. This architecture reduces the heat capacity and minimizes the thermal conductivity to 1/20 and 1/300, respectively, of earlier versions of these detectors, with consequent improvement in sensitivity and speed of response. The micromesh bolometers, intended to operate under an optical background set by thermal emission from an ambient-temperature space-borne telescope, are designed such that the random arrival of photons ("photon noise") dominates the noise sources arising from the detector and readout electronics. The micromesh is designed to be a highly thermally and optically efficient absorber with a limiting response time of about 100 s. The absorber and thermistor heat capacity are minimized in order to give rapid speed of response. Due to the minimization of the absorber volume, the dominant source of heat capacity arises from the thermistor.

  9. Random-phase metasurfaces at optical wavelengths

    NASA Astrophysics Data System (ADS)

    Pors, Anders; Ding, Fei; Chen, Yiting; Radko, Ilya P.; Bozhevolnyi, Sergey I.

    2016-06-01

    Random-phase metasurfaces, in which the constituents scatter light with random phases, have the property that an incident plane wave will diffusely scatter, hereby leading to a complex far-field response that is most suitably described by statistical means. In this work, we present and exemplify the statistical description of the far-field response, particularly highlighting how the response for polarised and unpolarised light might be alike or different depending on the correlation of scattering phases for two orthogonal polarisations. By utilizing gap plasmon-based metasurfaces, consisting of an optically thick gold film overlaid by a subwavelength thin glass spacer and an array of gold nanobricks, we design and realize random-phase metasurfaces at a wavelength of 800 nm. Optical characterisation of the fabricated samples convincingly demonstrates the diffuse scattering of reflected light, with statistics obeying the theoretical predictions. We foresee the use of random-phase metasurfaces for camouflage applications and as high-quality reference structures in dark-field microscopy, while the control of the statistics for polarised and unpolarised light might find usage in security applications. Finally, by incorporating a certain correlation between scattering by neighbouring metasurface constituents new types of functionalities can be realised, such as a Lambertian reflector.

  10. Random-phase metasurfaces at optical wavelengths

    PubMed Central

    Pors, Anders; Ding, Fei; Chen, Yiting; Radko, Ilya P.; Bozhevolnyi, Sergey I.

    2016-01-01

    Random-phase metasurfaces, in which the constituents scatter light with random phases, have the property that an incident plane wave will diffusely scatter, hereby leading to a complex far-field response that is most suitably described by statistical means. In this work, we present and exemplify the statistical description of the far-field response, particularly highlighting how the response for polarised and unpolarised light might be alike or different depending on the correlation of scattering phases for two orthogonal polarisations. By utilizing gap plasmon-based metasurfaces, consisting of an optically thick gold film overlaid by a subwavelength thin glass spacer and an array of gold nanobricks, we design and realize random-phase metasurfaces at a wavelength of 800 nm. Optical characterisation of the fabricated samples convincingly demonstrates the diffuse scattering of reflected light, with statistics obeying the theoretical predictions. We foresee the use of random-phase metasurfaces for camouflage applications and as high-quality reference structures in dark-field microscopy, while the control of the statistics for polarised and unpolarised light might find usage in security applications. Finally, by incorporating a certain correlation between scattering by neighbouring metasurface constituents new types of functionalities can be realised, such as a Lambertian reflector. PMID:27328635

  11. Random-phase metasurfaces at optical wavelengths.

    PubMed

    Pors, Anders; Ding, Fei; Chen, Yiting; Radko, Ilya P; Bozhevolnyi, Sergey I

    2016-01-01

    Random-phase metasurfaces, in which the constituents scatter light with random phases, have the property that an incident plane wave will diffusely scatter, hereby leading to a complex far-field response that is most suitably described by statistical means. In this work, we present and exemplify the statistical description of the far-field response, particularly highlighting how the response for polarised and unpolarised light might be alike or different depending on the correlation of scattering phases for two orthogonal polarisations. By utilizing gap plasmon-based metasurfaces, consisting of an optically thick gold film overlaid by a subwavelength thin glass spacer and an array of gold nanobricks, we design and realize random-phase metasurfaces at a wavelength of 800 nm. Optical characterisation of the fabricated samples convincingly demonstrates the diffuse scattering of reflected light, with statistics obeying the theoretical predictions. We foresee the use of random-phase metasurfaces for camouflage applications and as high-quality reference structures in dark-field microscopy, while the control of the statistics for polarised and unpolarised light might find usage in security applications. Finally, by incorporating a certain correlation between scattering by neighbouring metasurface constituents new types of functionalities can be realised, such as a Lambertian reflector. PMID:27328635

  12. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, R.P. Jr.; Crawford, M.H.

    1996-09-17

    The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1{lambda}) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%. 5 figs.

  13. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, Jr., Richard P.; Crawford, Mary H.

    1996-01-01

    A visible semiconductor laser. The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1.lambda.) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%.

  14. Patrolling the Sky at Long Wavelengths

    NASA Astrophysics Data System (ADS)

    Taylor, Gregory B.; Obenberger, K.; Hartman, J.; LWA Collaboration

    2013-01-01

    The first station of the Long Wavelength Array, “LWA1”, is located near the center of the Very Large Array in central New Mexico and has recently begun scientific operations as a stand-alone instrument with collecting area roughly equivalent to a 100m dish. The LWA1 images the sky in near-real-time using the “transient buffer - narrowband” (TBN) system which is operational with 258 dipoles, and a bandwidth of 70 kHz. This bandwidth can be placed at any frequency between 5 and 88 MHz. Near-real-time reduction of the data is accomplished by a dedicated cluster in the electronics shelter of the array. The LWA1 can also form up to 4 beams on the sky simultaneously with 16 MHz bandwidth in each of two tunings and full polarization which can provide higher senstivity for follow-up observations. Here we report on detection limits for prompt emission from approximately 30 Gamma-Ray Bursts at frequencies between 30 and 80 MHz. We also report on a number of bright transients of short duration that were detected in the course of searching the error-boxes of GRBs. Support for operations and continuing development of the LWA1 is provided by the National Science Foundation under grant AST-1139974 of the University Radio Observatory program.

  15. Multi-wavelength phase-shifting interferometry for micro-structures measurement based on color image processing in white light interference

    NASA Astrophysics Data System (ADS)

    Guo, Tong; Li, Feng; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2016-07-01

    Conventional multi-wavelength phase-shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. In this paper, the white light source, with a single-chip CCD color camera, is used to accomplish multi-wavelength phase-shifting interferometry. In addition, we propose an algorithm which combines white light phase-shifting algorithm, equivalent wavelength method and fringe order method to achieve measuring and calibrating the micro-structures ranging from nanometer scale to micrometer scale. Finally, the proposed method is validated by a traceable step height standard.

  16. Design of wavelength-selective waveplates using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Katayama, Ryuichi

    2013-03-01

    Wavelength-selective waveplates, which act either identically or differently for plural wavelengths, are useful for optical systems that handle plural wavelengths. However, they cannot be analytically designed because of the complexity of their structure. Genetic algorithm is one of the methods for solving optimization problems and is used for several kinds of optical design (e.g., design of thin films, diffractive optical elements, and lenses). I considered that it is effective for designing wavelength-selective waveplates also and tried to design them using the genetic algorithm for the first time to the best of my knowledge. As a result, four types of wavelength-selective waveplate for three wavelengths (405, 650, and 780 nm) were successfully designed. These waveplates are useful for Blu-ray Disc/Digital Versatile Disc/Compact Disc compatible optical pickups.

  17. Measurement of Magic Wavelengths for the ^{40}Ca^{+} Clock Transition.

    PubMed

    Liu, Pei-Liang; Huang, Yao; Bian, Wu; Shao, Hu; Guan, Hua; Tang, Yong-Bo; Li, Cheng-Bin; Mitroy, J; Gao, Ke-Lin

    2015-06-01

    We demonstrate experimentally the existence of magic wavelengths and determine the ratio of oscillator strengths for a single trapped ion. For the first time, two magic wavelengths near 396 nm for the ^{40}Ca^{+} clock transition are measured simultaneously with high precision. By tuning the applied laser to an intermediate wavelength between transitions 4s_{1/2}→4p_{1/2} and 4s_{1/2}→4p_{3/2}, the sensitivity of the clock transition Stark shift to the oscillator strengths is greatly enhanced. Furthermore, with the measured magic wavelengths, we determine the ratio of the oscillator strengths with a deviation of less than 0.5%. Our experimental method may be applied to measure magic wavelengths for other ion clock transitions. Promisingly, the measurement of these magic wavelengths paves the way to building all-optical trapped ion clocks. PMID:26196619

  18. Broadband Wavelength Spanning Holographic Polymer Dispersed Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Rai, Kashma; Shriyan, Sameet; Fontecchio, Adam

    2008-03-01

    Broadened interaction wavelength of holographic polymer dispersed liquid crystals (HPDLCs) have extensive applications in beam steering for instrument clusters, hyperspectral imaging, wavelength filtering and construction of lightweight optics. A novel simultaneous time and spatial multiplexing formation configuration is proposed here, to increase narrow wavelength reflecting notch to broad range wavelength spanning device. HPDLC films have electro-optic controllability by applying field. No moving parts, light weight, small footprint compared to prisms and lenses, high color purity make the broadband wavelength HPDLCs desirable for the above applications. Varying the incident laser beam exposure angles using motorized rotating stage, during formation is the key step here for their formation in a single medium. The fabricated broadband wavelength sensitive HPDLCs are characterized for the uniformity of the reflected peak and electro optic response. Their output wavefront is analyzed using wavefront analysis technique.

  19. Measurement of Magic Wavelengths for the ^{40}Ca^{+} Clock Transition.

    PubMed

    Liu, Pei-Liang; Huang, Yao; Bian, Wu; Shao, Hu; Guan, Hua; Tang, Yong-Bo; Li, Cheng-Bin; Mitroy, J; Gao, Ke-Lin

    2015-06-01

    We demonstrate experimentally the existence of magic wavelengths and determine the ratio of oscillator strengths for a single trapped ion. For the first time, two magic wavelengths near 396 nm for the ^{40}Ca^{+} clock transition are measured simultaneously with high precision. By tuning the applied laser to an intermediate wavelength between transitions 4s_{1/2}→4p_{1/2} and 4s_{1/2}→4p_{3/2}, the sensitivity of the clock transition Stark shift to the oscillator strengths is greatly enhanced. Furthermore, with the measured magic wavelengths, we determine the ratio of the oscillator strengths with a deviation of less than 0.5%. Our experimental method may be applied to measure magic wavelengths for other ion clock transitions. Promisingly, the measurement of these magic wavelengths paves the way to building all-optical trapped ion clocks.

  20. Identification of aerosol composition from multi-wavelength lidar measurements

    NASA Technical Reports Server (NTRS)

    Wood, S. A.

    1984-01-01

    This paper seeks to develop the potential of lidar for the identification of the chemical composition of atmospheric aerosols. Available numerical computations suggest that aerosols can be identified by the wavelength dependence of aerosol optical properties. Since lidar can derive the volume backscatter coefficient as a function of wavelength, a multi-wavelength lidar system may be able to provide valuable information on the composition of aerosols. This research theoretically investigates the volume backscatter coefficients for the aerosol classes, sea-salts, and sulfates, as a function of wavelength. The results show that these aerosol compositions can be characterized and identified by their backscatter wavelength dependence. A method to utilize multi-wavelength lidar measurements to discriminate between compositionally different thin aerosol layers is discussed.